TRICKLE-L digests for FEBRUARY 1996

From ab4el@ab4el.com Sat May 18 00:00 EDT 1996
From: Stephen Modena <modena@SunSITE.unc.edu>
Message-Id: <96051801.modena@sunsite.unc.edu>
Subject: TRICKLE-L LOG9602
Date: Sat, 18 May 1996 00:01:00 -0400 (EDT)

This is the compendium of TRICKLE-L digests for February 1996.

It was prepared from the daily digest mailings. Some digests
may be missing, because occasional mailings are lost en route.

From root@crcnis1.unl.edu Thu Feb 1 19:17 EST 1996
Date: Thu, 1 Feb 1996 13:04:49 -0600
Message-Id: <199602011904.AA03455@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 407

Contents:
Re: Manipulating O2 in soil (geoflow1@slip.net (Rodney Ruskin))
Re: Manipulating O2 in soil (GroAire@aol.com)
Re: Manipulating O2 in soil (GroAire@aol.com)
Re: Manipulating O2 in soil (GroAire@aol.com)
Plant Spacing (Courtney Krenz <74754.2006@compuserve.com>)
Re: Reply to PAM in Microirrigation? ("Blake L. Sanden" <blsanden@ucdavis.edu>)
Re: Plant Spacing (flowers@Rt66.com (wilderness flowers))
Re: Methyl bromide injection in subdrip ("Blake L. Sanden" <blsanden@ucdavis.edu>)

Date: Wed, 31 Jan 96 17:39:41 PST
From: geoflow1@slip.net (Rodney Ruskin)
Subject: Re: Manipulating O2 in soil

At 9:38 PM 1/29/96 -0600, GroAire@aol.com wrote:

> In regard to venturi or Mazzei injectors for the addition of atmospheric
>air into the soil.
>Mixing the air with the water is not the best way to aerate the soil. The
>water displaces the air and fills the pore spaces. What quantity of air that
>is left is insufficient for the purpose of stimulating the microflora of the
>soil.

Hi Dave,

Thanks for the information you have contributed, it is most useful.

Please tell us what is the best way of adding the air.

Rodney.

Date: Wed, 31 Jan 1996 21:41:08 -0500
From: GroAire@aol.com
Subject: Re: Manipulating O2 in soil

I'm in the business of designing subsurface aeration systems in conjunction
with SDI systems. Just as the irrigation system has to be tailored to fit the
target soil; so does the aeration system. I have air management programs just
as you are probably familiar with water management programs.Keep in mind that
I have been developing aeration systems for 15 years in regard to
agriculture, horticulture, and residential turf. I was the first in the U.S.
to design a subsurface system for turf and have had one commercially
operating for 12 years now. The first aeration system was installed 15 years
ago and was a success and a failure at the same time. I tried using da

Date: Wed, 31 Jan 1996 21:55:41 -0500
From: GroAire@aol.com
Subject: Re: Manipulating O2 in soil

OOPS! I guess I hit the wrong key. As i was saying, my first aeration system
was built using drainage tile. The plants responded as i knew they would - a
success. However;
the plants only responded in the first 30 feet of rows. As the rows grew
longer the rtesponse diminished - a failure. But with every failure comes new
knowledge or at least it should. All the air was coming out of the first 30'
of row ansd nothing was coming out later in the run. I needed a way to
regulate the air in the beginning and to force the air on down the length fo
the lateral. Hence the advent of turbulent flow tapes. I have worked with
almost every manufactured tape at one time or another and have settled on one
particular manufacturer as being the most efficient at deluivering the air
and the water independently of each other. I won't mention who that
manufacturer is online so I won't influence any one unless they are
requesting snail mail. I haqve flow rates and pressures established for
retrofitting existing systems or designing new systems.
The air can be engineered to regulate moisture levels or engineered to
stimulate the microflora. The air can be engineered to create heat for
warming the soil or it can be engineered to cool the soil.

Dave Enyeart
GroAire@aol.com

Date: Wed, 31 Jan 1996 21:59:04 -0500
From: GroAire@aol.com
Subject: Re: Manipulating O2 in soil

Dear Rodney, I noticed that in the beginning of you email adddress it is
listed as geoflow1. Isn't that a manufacturer of a root intrusion resistant
tape? And are you connected with that manufacturer as an end user or
supplier?

Dave Enyeart

Date: 31 Jan 96 19:27:14 EST
From: Courtney Krenz <74754.2006@compuserve.com>
Subject: Plant Spacing

I am looking for information on plant spacing when using plasticulture.

I am growing a tap root herb called Echinacea angustifolia (purple cone
flower).

I am currently using 12x12 inch spacing. I would like to go to an 8x10 inch
area per plant. Is there a formula I can use to determine the min. space
needed?

Courtney Krenz
Dakota Produce

Date: Thu, 01 Feb 1996 08:14:09 -0800
From: "Blake L. Sanden" <blsanden@ucdavis.edu>
Subject: Re: Reply to PAM in Microirrigation?

At 11:36 PM 1/28/96 -0600, you wrote:
>PAM or polyacrylamide, has been used for years to enhance soil structure.
>Traditionally used for furrow irrigation systems, the simple organic compound
>synthesized from natural gas, can reduce erosion, increase water infiltration
>rates and optimize lateral wetting.
>
>If it can be used in furrow systems, can it be injected in drip or microspray
>systems for the same purpose of increasing infiltration/lateral wetting?
>Could it reduce surface ponding?
>
>Anyone know of any applied practice of PAM in the drip arena?
>
>Richard Mead
>Trickle-L owner/manager
>
>

Studies by John Letey of UC Riverside and Phil Osterli, UC Coop Ext in
Modesto found that infiltration benefit for PAM in furrow irrigated row
crops only worked if the material got into the profile with the first or
second irrigation before much sealing or reduction in porosity had occured.
Adding PAM to sealed soil later in the season reduced sediment in the runoff
but had no benefit to infiltration. I assume the same scenario would hold
for soils on a micro system. Perhaps PAM may have a place in minimizing
water coming to the surface in newly installed subsurface drip systems on
"tight" soils that have just been ripped.

I think the cost was ~$9/ac-ft to treat.

Blake Sanden
Irrigation Farm Advisor, Kern County.

Date: Thu, 1 Feb 96 09:35:24 MST
From: flowers@Rt66.com (wilderness flowers)
Subject: Re: Plant Spacing

Courtney>

we have been field growing Echinacea for a number of years and have had good
results with a 8x10 spacing I am curious if your hydro growing plants have
much tap root or if you simply get a fibrous network of fine roots ?
ususally the herb processors are looking for mature heavy roots mass

Martin
>
> I am growing a tap root herb called Echinacea angustifolia (purple cone
>flower).
>
> I am currently using 12x12 inch spacing. I would like to go to an 8x10 inch
>area per plant. Is there a formula I can use to determine the min. space
>needed?
>
>Courtney Krenz
>Dakota Produce
>
>
>
Martin Connaughton
Wilderness Flowers
Rt 19 box 111-D
Santa Fe,NM 87505
phone/fax 505 988 3096
Email:flowers@rt66.com

Date: Thu, 01 Feb 1996 09:38:11 -0800
From: "Blake L. Sanden" <blsanden@ucdavis.edu>
Subject: Re: Methyl bromide injection in subdrip

At 09:36 PM 1/31/96 -0600, you wrote:
>OOPS! I guess I hit the wrong key. As i was saying, my first aeration system
>was built using drainage tile. The plants responded as i knew they would - a
>success. However;
>the plants only responded in the first 30 feet of rows. As the rows grew
>longer the rtesponse diminished - a failure. But with every failure comes new
>knowledge or at least it should. All the air was coming out of the first 30'
>of row ansd nothing was coming out later in the run. I needed a way to
>regulate the air in the beginning and to force the air on down the length fo
>the lateral. Hence the advent of turbulent flow tapes. I have worked with
>almost every manufactured tape at one time or another and have settled on one
>particular manufacturer as being the most efficient at deluivering the air
>and the water independently of each other. I won't mention who that
>manufacturer is online so I won't influence any one unless they are
>requesting snail mail. I haqve flow rates and pressures established for
>retrofitting existing systems or designing new systems.
>The air can be engineered to regulate moisture levels or engineered to
>stimulate the microflora. The air can be engineered to create heat for
>warming the soil or it can be engineered to cool the soil.
>
>Dave Enyeart
>GroAire@aol.com
>
>

TO Dave Enyeart,

Saw your note on Trickle-L. I'm very interested in your findings. I
haven't seen any hard, replicated data to convince me of the yield benefit
of air injection but it may be out there. My real interest is in
alternatives for methyl bromide injection. Since emitters are designed with
the viscosity of water in mind I've wondered about the hydraulics of air
flow and if uniform emmission from a 600-800 foot hose run was possible.
The timing of this issue is ripe for the veg crop and rose industry. Call
me, send some snail mail info.

How about the rest of you? Interested?

Blake Sanden
UC Cooperative Extension
1031 S. Mt Vernon Ave.
Bakersfield, CA 93307
805-837-0193
blsanden@ucdavis.edu

End of Digest
************************

From root@crcnis1.unl.edu Fri Feb 2 19:20 EST 1996
Date: Fri, 2 Feb 1996 13:05:34 -0600
Message-Id: <199602021905.AA27335@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 408

Contents:
Contacts in Hawaii? (raine@foes.usq.edu.au (Steven R. Raine))
Re: Oxygen in Soil (GrapeGrowr@aol.com)
Re: Reply to PAM in Microirrigation? (FLamm@oznet.ksu.edu (Freddie Lamm))
Emitter spacing discussion. (FLamm@oznet.ksu.edu (Freddie Lamm))
Re: Methyl bromide injection in subdrip (GroAire@aol.com)
Re: Oxygen in Soil (GroAire@aol.com)

Date: Fri, 02 Feb 1996 12:36:41 +1000
From: raine@foes.usq.edu.au (Steven R. Raine)
Subject: Contacts in Hawaii?

I am interested in contacting growers/researchers/extension staff using
trickle irrigation in Hawaii particularly in sugarcane production. If
there is anybody out there in "Trickleland" based in Hawaii or with suitable
contacts (eg Universities, HSPA, government bodies, private industry or
individual users) in Hawaii, it would be appreciated if you could direct
email me as soon as possible at "raine@foes.usq.edu.au".

I intend being in Hawaii during the first week of April this year and would
appreciate being able to discuss the operation and problems encountered with
trickle systems in the area. While I have a general interest in irrigation
(both trickle and surface) and soils, topics I would be particularly
interested in discussing during this visit include the operation, monitoring
and control of trickle systems, fertigation and chemical applications in
trickle systems, and the modelling of wetting patterns and/or
fertilisers/chemical movement under trickle irrigation systems.

Some background information on myself:

I am currently the lecturer in the Soil Science, Agricultural Science and
Land Studies subjects within the Faculty of Engineering and Surveying at the
University of Southern Queensland (in Toowoomba, Australia). My
undergraduate and Master's degree were in Agricultural Science majoring in
Land Resource Management. My PhD investigated the processes of soil
aggregate disruption and dispersion and the energies associated with
aggregate breakdown. Hence, I am probably more a soil physicist at heart
than any thing else. However, I have worked with the Conservation
Commission of the Northern Territory undertaking land resource surveys, as a
private consultant on several minesites undertaking soil surveys, and more
recently as a Research Scientist with the Bureau of Sugar Experiment
Stations (BSES) based in the Burdekin area (North Queensland). My research
with the BSES included general crop agronomy but focused on design and
management practices (primarily furrow irrigation) to improve irrigation
efficiencies within the industry. I am currently the co-supervisor of PhD
students investigating (a) the performance and efficiency of trickle
irrigation design and management practices within the Australian sugar
industry and (b) the infiltration functions and surface irrigation
performance for cracking clay soils.

Thank you for your assistance in this matter.

Cheers

Date: Fri, 2 Feb 1996 10:42:06 -0500
From: GrapeGrowr@aol.com
Subject: Re: Oxygen in Soil

A few years back, one of the most popular household fertilizers was a product
called oxygen plus made by Rodgers gardens in Newport Beach. I called them a
few years ago to gain understanding as to what material in the fertilizer mix
is the carrier of the O2 into the soil and they were very free with the
information (Ijust can't recall). I jumped through these hoops to see if it
was economically feasible on a commercial basis. In my opinion, the
economics of household gardening and commercial grape growing were pretty far
apart. Is there now a new, more economic method to increase the O2 in the
soil??

Date: 02 Feb 96 09:44:28 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Reply to PAM in Microirrigation?

Someone better check the compatibility and flow characteristics of
the PAM in water through the emitters during flow and after shutdown.
DO THIS IN LAB, not field. The stuff might gel up and cause
problems.-------------------------------------------------------------------
Freddie Lamm *
Research Agricultural Engineer *** o
KSU Northwest Research-Extension Center ***** /|\
105 Experiment Farm Road *******\\
Colby, Kansas 67701-1697 *********
Ph. 913-462-6281 ***********
FAX 913-462-2315 *************
Email:flamm@oznet.ksu.edu It's all downhill from here.

------ THERE'S NO DOMAIN LIKE OZ, THERE'S NO DOMAIN LIKE OZ. ------

Date: 02 Feb 96 10:03:28 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Emitter spacing discussion.

Ed Martin:
Here is a conceptual discussion of some of the aspects of
emitter spacing and related issues from a paper I gave on SDI design
considerations for Corn given at a regional meeting. Some of the
previous replies did not really address the hydraulic issues. For
what it's worth.

****EXCERPTS FROM***

DESIGN AND MANAGEMENT CONSIDERATIONS FOR SUBSURFACE DRIP
IRRIGATION SYSTEMS

Freddie R. Lamm Danny H. Rogers William E. Spurgeon

........HYDRAULIC DESIGN
Successful operation of a SDI system begins with a proper
hydraulic design which will satisfy the constraints dictated by
crop, soil type and characteristics, field size, shape, and
topography, and water source and supply. Disregarding design
constraints will likely result in a system that is costly in both
time and money to operate and will likely increase the chance of
system failure. System failure might result in the loss of the
total capital investment.

Crops and Soils Considerations

The crop and soil type will dictate SDI system capacity,
dripline spacing, emitter spacing, and installation depth. The
SDI system capacity must be able to satisfy the peak water
requirement of the crop through the combination of the applied
irrigation amount, precipitation, and stored soil water. The
system capacity will influence the selection of the dripline
flowrate and the zone size (area served by each submain).
Improper selection of these items can result in more expensive
systems to install and operate.

The dripline spacing is obviously an important factor in
system cost, and economics suggest wider spacings. However, wide
spacing will not uniformly supply crop water needs and will
likely result in excess deep percolation on many soil types. The
dripline spacing is dictated by the lateral extent of the crop
root zone, lateral soil water redistribution, and in-season
precipitation. Studies on silt loam soils in western Kansas
conducted by Kansas State University have indicated that a 60-
inch dripline spacing is optimal for a corn-row spacing of 30
inches. Soils that have a restrictive clay layer below the
dripline installation depth would probably allow a wider dripline
spacing without affecting crop yield. Wider spacings may also be
allowable in areas of increased precipitation as the dependency
of the crop on irrigation is decreased. The emitter spacing is
dictated by the same factors affecting dripline spacing.
However, generally, the emitter spacing is less than the dripline
spacing. As a rule of thumb, dripline spacing is related to crop
row spacing while emitter spacing is more closely related to crop
plant spacing. One of the inherent advantages of a SDI system is
the ability to irrigate only a fraction of the crop root zone.
Careful attention to dripline spacing and emitter spacing are,
therefore, key factors in achieving the purpose of water
conservation and water quality protection.

The installation depth is also related to the crop and soil
type. Deep installations reduce the potential for soil
evaporation and also allow for a wider range of tillage
practices. However, deep installations may limit the
effectiveness of the SDI system for seed germination and may
restrict availability of surface-applied nutrients. Acceptable
results have been obtained with installation depth of
approximately 18 inches in KSU studies in western Kansas on deep
silt loam soils. Dripline should probably be installed above any
restrictive clay layers that might exist in the soil. This would
help increase lateral soil water redistribution.

Field Size, Shape, and Topography
The overall field size may be limited by the available water
supply and capacity. The ability to economically adjust the size
of the irrigated field to the available water supply is a
distinct advantage of SDI systems compared to center pivot
sprinkler systems. If sufficient water supply is available, the
field size, shape, and topography, along with the dripline
hydraulic characteristics, will dictate the number of zones.
Minimizing the number of necessary zones will result in a more
economical system to install and operate.

Whenever possible, dripline laterals should be installed
downslope on slopes of less than 2%. On steeper terrain, the
driplines should be made along the field contour and/or
techniques for pressure control should be employed.

..................
Friction losses increase with length of run.........

Friction losses also increase with the velocity of water in
the dripline. For a given inside diameter of line, friction
losses will be greater for driplines with higher flowrates. Some
designers prefer higher capacity driplines
because they are less subject to plugging and allow more
flexibility in scheduling irrigation. However, if larger-
capacity driplines are chosen, the length of run may need to be
reduced to maintain good uniformity. Additionally, the zone area
may need to be reduced to keep the flowrate within the
constraints of the water supply system. Decreasing the length of
run or the zone area increases the cost of both installation and
operation.

The land slope can have either a positive or negative effect
on the pressure distribution along the dripline lateral.
Irrigating uphill will always result in increasing pressure
losses along the lateral length. If the downhill slope is too
large, the flowrate at the end of the line may be unacceptably
high..........

.......... Chemical water treatment may be required on a
continuous or intermittent basis. Acids are sometimes used to
prevent plugging and also to help renovate partially plugged
driplines. The need for treatment is dictated by the water
source and the emitter size.

Freddie
*

Freddie Lamm *
Research Agricultural Engineer *** o
KSU Northwest Research-Extension Center ***** /|\
105 Experiment Farm Road *******\\
Colby, Kansas 67701-1697 *********
Ph. 913-462-6281 ***********
FAX 913-462-2315 *************
Email:flamm@oznet.ksu.edu It's all downhill from here.

------ THERE'S NO DOMAIN LIKE OZ, THERE'S NO DOMAIN LIKE OZ. ------

Date: Fri, 2 Feb 1996 12:14:39 -0500
From: GroAire@aol.com
Subject: Re: Methyl bromide injection in subdrip

Snail mail cometh. Incidently, there is Rutgers, University of Nebraska, and
Washington State University that have performed third party documentation for
us in regard to air injection. Excerptsd of those reports are included.
Recently, I have received letters of endorsement from the Natural Resource
Conservation Service -USDA. One being an agronomist and the other being a
range and plant specialist. But the real indorsements come from the growers
that are utilizing the system.

Dave Enyeart
GroAire@aol.com

Date: Fri, 2 Feb 1996 12:22:24 -0500
From: GroAire@aol.com
Subject: Re: Oxygen in Soil

Absolutely. the system I use is enhances all the microflora of the soil and
increases root mass substantially. I f the root mass increases accordingly
then the oxygen has to be present for respiration. If I haven't already snail
mailed you then leave your address and I'll get you on the list for the next
mailing.

Dave Enyeart
GroAire@aol.com

End of Digest
************************

From root@crcnis1.unl.edu Sat Feb 3 19:19 EST 1996
Date: Sat, 3 Feb 1996 13:06:10 -0600
Message-Id: <199602031906.AA11107@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 409

Contents:
RE: Emitter spacing discussion. (Manrique Brenes <mjbrenes@ucdavis.edu>)
Re: Manipulating O2 in soil (LodiCraig@aol.com)
Emitter' s Spacing (Yossi Ingber <100320.3653@compuserve.com>)

Date: Fri, 2 Feb 1996 12:29:31 -0800
From: Manrique Brenes <mjbrenes@ucdavis.edu>
Subject: RE: Emitter spacing discussion.

In the previous discussion I assumed everyone understands the hydrualics =
of a tape line and the impact of flowrate and emitter spacing on =
uniformity.=20
Another important consideration in emitter spacing is the effect of =
emitter plugging and its consequences. The closer the emitter spacing =
the less impact a plugging problem will have on the crop, i.e., if we =
have an instalation with emitter spacings of 1 meter and one of this =
emitter plugs, then we will have an effective spacing of 2 meters and it =
will be very difficult to supply any water to a fair portion of plants =
between the two non plugged emitters. If the same happens with a system =
that has emitters every 20 cm then the impact on the plants will be less =
since there will probably be some water reaching the rootzone of all =
plants in the row..
Another aspect is seed germination. In Central America many melon =
growers change to 20 and 23 cm spacings from 50 and 60 cm since it was =
hard for them to germinate their second crop. Even in heavy clay soils =
it was very difficult do to soil cracking. Once the soil cracked it took =
them a heavy application to wet all seeds, so heavy, that the soil =
profile became anaerobic creating many pathogenic problems.

Manrique Brenes
Bio & Ag Eng.
UC Davis

----------
From: Freddie Lamm[SMTP:FLamm@oznet.ksu.edu]
Sent: Friday, February 02, 1996 8:38 AM
To: Multiple recipients of list
Subject: Emitter spacing discussion.

Ed Martin:
Here is a conceptual discussion of some of the aspects of
emitter spacing and related issues from a paper I gave on SDI design
considerations for Corn given at a regional meeting. Some of the
previous replies did not really address the hydraulic issues. For
what it's worth.

****EXCERPTS FROM***

DESIGN AND MANAGEMENT CONSIDERATIONS FOR SUBSURFACE DRIP
IRRIGATION SYSTEMS

Freddie R. Lamm Danny H. Rogers William E. Spurgeon

........HYDRAULIC DESIGN
Successful operation of a SDI system begins with a proper
hydraulic design which will satisfy the constraints dictated by
crop, soil type and characteristics, field size, shape, and
topography, and water source and supply. Disregarding design
constraints will likely result in a system that is costly in both
time and money to operate and will likely increase the chance of
system failure. System failure might result in the loss of the
total capital investment.

Crops and Soils Considerations

The crop and soil type will dictate SDI system capacity,
dripline spacing, emitter spacing, and installation depth. The
SDI system capacity must be able to satisfy the peak water
requirement of the crop through the combination of the applied
irrigation amount, precipitation, and stored soil water. The
system capacity will influence the selection of the dripline
flowrate and the zone size (area served by each submain).
Improper selection of these items can result in more expensive
systems to install and operate.

The dripline spacing is obviously an important factor in
system cost, and economics suggest wider spacings. However, wide
spacing will not uniformly supply crop water needs and will
likely result in excess deep percolation on many soil types. The
dripline spacing is dictated by the lateral extent of the crop
root zone, lateral soil water redistribution, and in-season
precipitation. Studies on silt loam soils in western Kansas
conducted by Kansas State University have indicated that a 60-
inch dripline spacing is optimal for a corn-row spacing of 30
inches. Soils that have a restrictive clay layer below the
dripline installation depth would probably allow a wider dripline
spacing without affecting crop yield. Wider spacings may also be
allowable in areas of increased precipitation as the dependency
of the crop on irrigation is decreased. The emitter spacing is
dictated by the same factors affecting dripline spacing.
However, generally, the emitter spacing is less than the dripline
spacing. As a rule of thumb, dripline spacing is related to crop
row spacing while emitter spacing is more closely related to crop
plant spacing. One of the inherent advantages of a SDI system is
the ability to irrigate only a fraction of the crop root zone.
Careful attention to dripline spacing and emitter spacing are,
therefore, key factors in achieving the purpose of water
conservation and water quality protection.

The installation depth is also related to the crop and soil
type. Deep installations reduce the potential for soil
evaporation and also allow for a wider range of tillage
practices. However, deep installations may limit the
effectiveness of the SDI system for seed germination and may
restrict availability of surface-applied nutrients. Acceptable
results have been obtained with installation depth of
approximately 18 inches in KSU studies in western Kansas on deep
silt loam soils. Dripline should probably be installed above any
restrictive clay layers that might exist in the soil. This would
help increase lateral soil water redistribution.

Field Size, Shape, and Topography
The overall field size may be limited by the available water
supply and capacity. The ability to economically adjust the size
of the irrigated field to the available water supply is a
distinct advantage of SDI systems compared to center pivot
sprinkler systems. If sufficient water supply is available, the
field size, shape, and topography, along with the dripline
hydraulic characteristics, will dictate the number of zones.
Minimizing the number of necessary zones will result in a more
economical system to install and operate.

Whenever possible, dripline laterals should be installed
downslope on slopes of less than 2%. On steeper terrain, the
driplines should be made along the field contour and/or
techniques for pressure control should be employed.

..................
Friction losses increase with length of run.........

Friction losses also increase with the velocity of water in
the dripline. For a given inside diameter of line, friction
losses will be greater for driplines with higher flowrates. Some
designers prefer higher capacity driplines
because they are less subject to plugging and allow more
flexibility in scheduling irrigation. However, if larger-
capacity driplines are chosen, the length of run may need to be
reduced to maintain good uniformity. Additionally, the zone area
may need to be reduced to keep the flowrate within the
constraints of the water supply system. Decreasing the length of
run or the zone area increases the cost of both installation and
operation.

The land slope can have either a positive or negative effect
on the pressure distribution along the dripline lateral.
Irrigating uphill will always result in increasing pressure
losses along the lateral length. If the downhill slope is too
large, the flowrate at the end of the line may be unacceptably
high..........

.......... Chemical water treatment may be required on a
continuous or intermittent basis. Acids are sometimes used to
prevent plugging and also to help renovate partially plugged
driplines. The need for treatment is dictated by the water
source and the emitter size.

Freddie
*

Date: Fri, 2 Feb 1996 21:12:56 -0500
From: LodiCraig@aol.com
Subject: Re: Manipulating O2 in soil

In a message dated 96-01-31 21:42:42 EST, you write:

>I'm in the business of designing subsurface aeration systems in conjunction
>with SDI systems. Just as the irrigation system has to be tailored to fit
the
>target soil; so does the aeration system. I have air management programs
just
>as you are probably familiar with water management programs.

In your opinion, would a subsurface drip system designed for water be capable
of being used for air injection? While it may not be efficient, it might be
worthwhile to see if there is a growth or quality response. It would not be
difficult to install a few check valves in the hose and inject air to
demonstrate the beneficial effect. Would a small compressor suffice for a
small test plot?

Assuming a sandy loam (e.g. Hanford Sandy Loam) during wet spring conditions,
how many standard cubic feet of air would you try to inject per acre per day,
and at what pressure? What results might I expect to observe in a permanent
crop like grapes?

Craig Thompson

Date: 03 Feb 96 11:24:13 EST
From: Yossi Ingber <100320.3653@compuserve.com>
Subject: Emitter' s Spacing

The discussion that goes on emitter's spacing seems to neglect a
major factor which is the discharge of each outlet . Heavy load of
research is available on water dispersion in soil subject to emitter's
discharge . You may find on the market various emitter's discharges .
The inter-relationship should be lateral length, maximal flow variation
along the lateral , emitter's discharge that achieves resonable wetted
volume , emitter's spacing .
Ilan Bar ( Netafim's agronomist in Florida ) did a comparison of few
alternatives spacing vs. emitter's discharge . Amaizingly , the optimal
yield was not achieved by using short spacings , mainly due to little
volume of soil which has a balance of air and water.
Yossi Ingber / Netafim-Israel

End of Digest
************************

From root@crcnis1.unl.edu Sun Feb 4 19:19 EST 1996
Date: Sun, 4 Feb 1996 13:06:11 -0600
Message-Id: <199602041906.AA20397@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 410

Contents:
Anyone have experience with Asparagus under SDI? (Jerome Pier <jpier@interramp.com>)
Greenhouse Tomato Grower/Calcium Precipitation et al (Mike & Dawn Lydon <ride0126@ride.ri.net>)
RE: Greenhouse Tomato Grower/Calcium Precipitation et al (Goldberg <goldberg@eden.com>)
Re: Anyone have experience with Asparagus under SDI? (flowers@Rt66.com (wilderness flowers))
RE: Emitter' s Spacing (Manrique Brenes <mjbrenes@ucdavis.edu>)
Re: Oxygen in Soil ("M. Meron" <MERON@migal.co.il>)

Date: Sat, 03 Feb 1996 14:35:24 -0800
From: Jerome Pier <jpier@interramp.com>
Subject: Anyone have experience with Asparagus under SDI?

Dear Tricklers,

I have the honor to be involved with a grower in Fresno County,
CA who is trying asparagus for the first time under buried drip. I was
wondering if anyone on the list can tell me what I should know about
drip asparagus as far as irrigation and fertigation scheduling as well
as pest and disease problems and other hazards like root intrusion and
tape strangulation.
I will assume this is a subject of limited interest so I request
that all email be forwarded to my personal email address,
jpier@interramp.com, and not to the discussion list. If and when I get
some replies, I will summarize the mail I have received and post to the
list. I look forward to hearing from you.

Sincerely,
--
Jerome Pier
Soil Scientist/Agronomist
Netafim Irrigation, Inc.
jpier@interramp.com

Date: Sat, 3 Feb 1996 18:11:03 -0500
From: Mike & Dawn Lydon <ride0126@ride.ri.net>
Subject: Greenhouse Tomato Grower/Calcium Precipitation et al

Hi Richard
Before I describe my problems with my SURFACE irrigation system, let me
intorduce myself.
My name in Mike Lydon
Address: Lydon Family Tomatoes
Tiverton, Rhode Island 02878
I have 14,000 ft sq of greenhouse tomatoes under poly houses

>1) Briefly, what is your affiliation with trickle/drip irrigation?
I use Netafilm 1/2 GPH drippers for each plant with a stake which allows the
fluid to drip in at the surface near the stem. I plant in grow bags, 4
plants/3 cuft of media. Dripper spacing is 18 inches.
>
>2) What crops or plants do you use drip irrigation on?
Only Tomatoes
>
>3) If using subsurface drip irrigation, what is the average depth of
>placement of the drip lateral?
NA
>
>4) What problems have you encountered with drip irrigation?
Some of the drippers don't maintain the specified drip rate. I suspect
calcium precipitation
>
>5) Fertigation is a real advantage of drip irrigation. What form of N, P and
>K have you been trying and to what success?
Soluable CaNO3 at 1 Lb / 100 Gal feed water
Grace HydroSol (5-11-26) at .833 Lb / 100 Gal feed water
K2SO4 at .3 Lb / 100 Gal feed water
>
>6) Have you experienced a reduction in fertilizer and/or water use?
YES!
>
>7) Do you have water quality problems? If so, how do you tackle the situation?
NO
>
>8) How frequent do you irrigate? Many times a day or just one long session
>per day or several days?
Variable----6 to 8 X per day at 5 to 15 min ea
>
>9) Do you have rodent damage? If so, how do you control the problem?
No
>
>10) Are you pleased with the uniformity of your system or systems? Were they
>designed correctly?
Yes
>
>11) How did you find out about our mailing list?
I found it on the Hobby Greenhouse List
>

I would like to know how to remove the deposits that build up in the
drippers and irrigation lines as part of preventative maintenance between
plantings.

Can anyone think of any means to reduce the buildup of precipates as a
solution that I can inject periodically.

I hope that I can contribute in the future to other growers with hydrophonic
crops.

Mike Lydon
>

Date: Sat, 3 Feb 1996 19:58:38 -0600
From: Goldberg <goldberg@eden.com>
Subject: RE: Greenhouse Tomato Grower/Calcium Precipitation et al

------ =_NextPart_000_01BAF272.09049A00
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

Mike and Dawn: First you should cut open one of the emitters and =
examine the teeth (tortuous path). If you see white precipitate, then =
probably calcium and/or magnesium is precipitating out. On a regular =
basis, you should make sure your Ph is as low as it should be for =
tomatoes anyway. Higher Ph greatly facilitates Ca precipitation. For =
remedial action, I'd suggest injection of fertilizer grade phosphoric =
acid. Make sure the strength injected is strong enough to lower your Ph =
substantially. In mixing your fertilizer concentrates, take into =
account the P that you are now injecting. Slowly, if Ph is lowered for =
a period of time, your precipitate should dissolve.

In between plantings, you might try sulfuric acid in high strength, and =
just let it sit in the lines.

Rick Goldberg
Ex-greenhouse tomato grower with Netafim 2 liter/hr. emitters =20

----------
From: Mike & Dawn Lydon[SMTP:ride0126@ride.ri.net]
Sent: Saturday, February 03, 1996 5:00 PM
To: Multiple recipients of list
Subject: Greenhouse Tomato Grower/Calcium Precipitation et al

Hi Richard
Before I describe my problems with my SURFACE irrigation system, let me
intorduce myself.
My name in Mike Lydon
Address: Lydon Family Tomatoes
Tiverton, Rhode Island 02878
I have 14,000 ft sq of greenhouse tomatoes under poly houses

>1) Briefly, what is your affiliation with trickle/drip irrigation?
I use Netafilm 1/2 GPH drippers for each plant with a stake which allows =
the
fluid to drip in at the surface near the stem. I plant in grow bags, 4
plants/3 cuft of media. Dripper spacing is 18 inches.
>
>2) What crops or plants do you use drip irrigation on?
Only Tomatoes
>
>3) If using subsurface drip irrigation, what is the average depth of
>placement of the drip lateral?=20
NA
>
>4) What problems have you encountered with drip irrigation?
Some of the drippers don't maintain the specified drip rate. I suspect
calcium precipitation
>
>5) Fertigation is a real advantage of drip irrigation. What form of N, =
P and
>K have you been trying and to what success?
Soluable CaNO3 at 1 Lb / 100 Gal feed water
Grace HydroSol (5-11-26) at .833 Lb / 100 Gal feed water
K2SO4 at .3 Lb / 100 Gal feed water
>
>6) Have you experienced a reduction in fertilizer and/or water use?
YES!
>
>7) Do you have water quality problems? If so, how do you tackle the =
situation?
NO
>
>8) How frequent do you irrigate? Many times a day or just one long =
session
>per day or several days?
Variable----6 to 8 X per day at 5 to 15 min ea
>
>9) Do you have rodent damage? If so, how do you control the problem?
No
>
>10) Are you pleased with the uniformity of your system or systems? Were =
they
>designed correctly?
Yes
>
>11) How did you find out about our mailing list?
I found it on the Hobby Greenhouse List
>

I would like to know how to remove the deposits that build up in the
drippers and irrigation lines as part of preventative maintenance =
between
plantings.

Can anyone think of any means to reduce the buildup of precipates as a
solution that I can inject periodically.

I hope that I can contribute in the future to other growers with =
hydrophonic
crops.

Mike Lydon
>

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------ =_NextPart_000_01BAF272.09049A00--

Date: Sat, 3 Feb 96 21:05:21 MST
From: flowers@Rt66.com (wilderness flowers)
Subject: Re: Anyone have experience with Asparagus under SDI?

,Jerome Pier
if dave enyeart does not get back to you through the list serv i'd sugest
contacting him at GroAire@aol.com he seems to one of the best resoures on
the listserve for these problems.
>
>
>Sincerely,
>--
>Jerome Pier
>Soil Scientist/Agronomist
>Netafim Irrigation, Inc.
>jpier@interramp.com
>
>
Martin Connaughton
Wilderness Flowers
Rt 19 box 111-D
Santa Fe,NM 87505
phone/fax 505 988 3096
Email:flowers@rt66.com

Date: Sat, 3 Feb 1996 21:53:47 -0800
From: Manrique Brenes <mjbrenes@ucdavis.edu>
Subject: RE: Emitter' s Spacing

"Amaizingly , the optimalyield was not achieved by using short =
spacings"
I also find it amazing to believe it since it goes againts almost all of =
mypractical experiences. Is this study independent? Has it been =
verified? If so please post me the references.

Thanks.

Manrique Brenes
BAE-UCD
----------
From: Yossi Ingber[SMTP:100320.3653@compuserve.com]
Sent: Saturday, February 03, 1996 8:21 AM
To: Multiple recipients of list
Subject: Emitter' s Spacing=20

The discussion that goes on emitter's spacing seems to neglect =
a
major factor which is the discharge of each outlet . Heavy =
load of
research is available on water dispersion in soil subject to =
emitter's
discharge . You may find on the market various emitter's =
discharges .
The inter-relationship should be lateral length, maximal flow =
variation
along the lateral , emitter's discharge that achieves resonable =
wetted
volume , emitter's spacing .=20
Ilan Bar ( Netafim's agronomist in Florida ) did a comparison =
of few
alternatives spacing vs. emitter's discharge ., mainly due to =
little
volume of soil which has a balance of air and water.
Yossi Ingber / Netafim-Israel

Date: Sun, 4 Feb 1996 11:07:22 GMT+0200
From: "M. Meron" <MERON@migal.co.il>
Subject: Re: Oxygen in Soil

We are involved in reclamation of the Hula peat soils, degraded in a dry
climate after their drainage.

One of the possible solutions considered is the use of SDI for irrigation
and soil aeration to reduce microbial competition on oxigen with the roots.

Woud appreciate your inputs and experience.

M. Meron
=========================================================================
MIGAL Galilee Technology Center Crop Ecology Laboratory
Kiryat Shmona PO Box 90 000 Rosh Pina 12 100 ISRAEL
Phone +972-6-953559 Fax: +972-6-944980 Email: MERON@migal.co.il
=========================================================================

End of Digest
************************

From root@crcnis1.unl.edu Mon Feb 5 19:20 EST 1996
Date: Mon, 5 Feb 1996 13:06:57 -0600
Message-Id: <199602051906.AA08511@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 411

Contents:
Re: Manipulating O2 in soil (GroAire@aol.com)
Re: Emitter' s Spacing (GroAire@aol.com)
Re: Greenhouse Tomato Grower/Calcium Precipitation et al (GroAire@aol.com)
Re: Oxygen in Soil (GroAire@aol.com)

Date: Sun, 4 Feb 1996 21:28:49 -0500
From: GroAire@aol.com
Subject: Re: Manipulating O2 in soil

Dear Craig,

I hesitate giving generic information as I've stated before that I design
systems for each piece of ground individually. It is possible to design a
small test plot with a small compressor as I have installed lots of gardens.
If you email me your snail mail address then I will send you a parameters
worksheet to fill out. Once I have the detailed info then I can design a
system for you.

In regard to long range effects of aeration on grapes. As i have never worked
with grapes, I cannot answer specifically. However, in long term
installations such as trees or honeysuckle bushes that I have worked with the
benefit is eveident in the girth of the trunks and the number of branches as
the height of the tree was increased. The blue spruce and the ponderosa
received aeration treatments in the first two years of their life when they
were transplanted into the research plot. They were 3 feet tall and there
were twelve trees in the row. Six trees received aeration and six did not.
The irrigation treatment was the same for both groups throughout the past 13
years. The stand that received aeration treatments is today 6-8 feet taller
and has a much greater circumference, although I've never measured the
latter.

I know that whatever type of plant that I've worked with over the past 15
years has responded with a greater root mass which translated in more and
better foliage or fruit.

At one point I worked with an existing apple orchard that was 25 years old.
The yield did not increase with the aeration treatments, but the aerated plot
matured 3 weeks ahead of the nonaerated plot. I don't know for a fact but I
suspect that the tree had an established root mass and that decided the
yield. What I did effect was the down time of the roots after irrigations or
precipitation. Everytime a plant is irrigated the roots shut down until the
pore space is replaced (oxygen) by gravity pulling the excess moisture
downward and atmospheric air being pulled in from the surface. What I did was
decrease that amount of down time during the length of the season. Again this
is something that I see replicated throughout the installations in increasing
the length of the growing season or earlier maturity.

Looking forward to working with you

Dave Enyeart
GroAire@aol.com

Date: Sun, 4 Feb 1996 21:34:27 -0500
From: GroAire@aol.com
Subject: Re: Emitter' s Spacing

I raelly liked your last statement.

Dave Enyeart
GroAire@aol.com

Date: Sun, 4 Feb 1996 21:50:31 -0500
From: GroAire@aol.com
Subject: Re: Greenhouse Tomato Grower/Calcium Precipitation et al

Hello Mike,

I work with tomato greenhouses in Missouri, Nebraska, Colorado, and soon
Arizona.The predominance of my growers are organic however. We have been
using ceramic magnets to alter the polarity of the molecules so that they
cannot attach to the emitters or the evaporative pads. In our country,
calcium carbonates are an inherant problem in the water and it will render
the cooling pads and drip emmiters either useless or will suffer from
reduced uniformity and efficiency. I've seen it replicated enough that I'm a
solid believer in the system. If you would like more info, email me your
snail mail address.

Dave Enyeart
GroAire@aol.com

Date: Sun, 4 Feb 1996 22:10:22 -0500
From: GroAire@aol.com
Subject: Re: Oxygen in Soil

All you have to do is go ask the Palistinian Agricultural relief Committee
about subaeration & SDI. I understand I have two unauthorized plots in
Jericho and the Gaza Strip. One was successful and the other wwas not. The
committee complained to the Norwegian Government as they were backing the
Norwegian businessman who originall stole the design from me. We have offered
our aid in straightening out the problems that have ocurred to the Committee,
but have not had a formal reply as of yet.

Dave Enyeart
GroAire@aol.com
303-650-0472 U.S.A.

End of Digest
************************

From root@crcnis1.unl.edu Tue Feb 6 19:18 EST 1996
Date: Tue, 6 Feb 1996 13:07:32 -0600
Message-Id: <199602061907.AA00162@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 412

Contents:
Drip/Furrow Irrig.of Pistachios (stein@wiz.uni-kassel.de (Thomas-M. Stein))
Re: Anyone have experience with Asparagus under SDI? (FLamm@oznet.ksu.edu (Freddie Lamm))

Date: Tue, 6 Feb 1996 16:05:50 +0100 (MEZ)
From: stein@wiz.uni-kassel.de (Thomas-M. Stein)
Subject: Drip/Furrow Irrig.of Pistachios

Dear Colleagues,

Our Department is conducting an irrigation research project on
pistachios under drip irrigation in Iran.

We are comparing drip irrigation with the traditional furrow
method. We also altered the traditional scheduling using a class
A-pan and applying water on a rate of 0.6, 0.8, 1.0 and 1.2 times
the reading of the class A-pan.

So far the results have been promising. Even drip irrigation
strongly increased vegetative growth, at the same time the yield
and quality seem to be positively affected as well.

We would greatly appreciate any information on similar
experiences with drip irrigated pistachios or some useful
references.

Any hint will be appreciated

Yours sincerely

Dr. Peter Wolff (wolff@wiz.uni-kassel.de)
Thomas Stein (stein@wiz.uni-kassel.de)

______________________________________________________________________________

Thomas-M. Stein
University of Kassel (FB11) Phone : (+49)-5542-98-1632
Dep. of Rural Engineering and Fax : (+49)-5542-98-1588
Natural Resource Protection Email : stein@wiz.uni-kassel.de
Nordbahnhofstr. 1a WWW : http://www.wiz.uni-kassel.de/kww/
D-37213 Witzenhausen, GERMANY List owner: IRRIGATION-L@listserv.gmd.de
______________________________________________________________________________

Date: 06 Feb 96 08:54:27 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Anyone have experience with Asparagus under SDI?

Jerome:
I believe there were some articles on irrigation scheduling and
fertigation of asparagus in the 1990 Proceedings of the 3rd National
Irrigation Symposium, "Visions of the Future"in Phoenix, Arizona.
This publication is available fom ASAE. I'm not sure what the
method of irrigation was.

Freddie
*-------------------------------------------------------------------
Freddie Lamm *
Research Agricultural Engineer *** o
KSU Northwest Research-Extension Center ***** /|\
105 Experiment Farm Road *******\\
Colby, Kansas 67701-1697 *********
Ph. 913-462-6281 ***********
FAX 913-462-2315 *************
Email:flamm@oznet.ksu.edu It's all downhill from here.

------ THERE'S NO DOMAIN LIKE OZ, THERE'S NO DOMAIN LIKE OZ. ------

End of Digest
************************

From root@crcnis1.unl.edu Wed Feb 7 19:25 EST 1996
Date: Wed, 7 Feb 1996 13:14:12 -0600
Message-Id: <199602071914.AA22124@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 413

Contents:
Re: Anyone have experience with Asparagus under SDI? (gideon oron <gidi@bgumail.bgu.ac.il>)
Recommendations for sub surface irrigation. (Diana M Magarian <mille161@maroon.tc.umn.edu>)

Date: Wed, 7 Feb 1996 13:31:55 +0200 (IST)
From: gideon oron <gidi@bgumail.bgu.ac.il>
Subject: Re: Anyone have experience with Asparagus under SDI?

Dear Dr. Pier
Can you pleaselet me know the followings:
1) Mean depth of the Aspargus root zone.
2)Frequency of irrigation (how many times per week)
3) Amount of water to be applied (or the crop coofficient as realted
to a measure such as class "A" pan).
4)Length of growing season (Days ?)
5)Fertilzation needs, primarily NPK.
thanks for your attention
Gideon Oron, Israel
E-Mail:Gidi@BGUmail.bgu.ac.il

On Sat, 3 Feb 1996, Jerome Pier wrote:

> Dear Tricklers,
>
> I have the honor to be involved with a grower in Fresno County,
> CA who is trying asparagus for the first time under buried drip. I was
> wondering if anyone on the list can tell me what I should know about
> drip asparagus as far as irrigation and fertigation scheduling as well
> as pest and disease problems and other hazards like root intrusion and
> tape strangulation.
> I will assume this is a subject of limited interest so I request
> that all email be forwarded to my personal email address,
> jpier@interramp.com, and not to the discussion list. If and when I get
> some replies, I will summarize the mail I have received and post to the
> list. I look forward to hearing from you.
>
> Sincerely,
> --
> Jerome Pier
> Soil Scientist/Agronomist
> Netafim Irrigation, Inc.
> jpier@interramp.com
>

Date: Wed, 7 Feb 1996 13:12:37 -0600 (CST)
From: Diana M Magarian <mille161@maroon.tc.umn.edu>
Subject: Recommendations for sub surface irrigation.

I need recommendations for what type, brand, etc. of irrigation material
we should use for an upcoming study. The tubing is to be buried 2 feet
below the surface of the soil. The soil is at the site is a Hubbard
loamy sand (sandy, Udorothentic Haploboroll). Alfafla will be seeded on
the site and it will be treated with 15N isotope solution, using the
irrigation system. Last year we conducted a study using Chapin drip tape
for surface application of the nitrogen solution, but I am not sure if
this can be buried. The main concern is uniformity, making sure each
plant ( which will be equally spaced) has equal opportunity to receive
the solution. I am a new comer to this subject, so if you could please
help and recommend what we should do it would be greatly appreciated.

diana (e-mail-mille161@maroon.tc.umn.edu)

End of Digest
************************

From root@crcnis1.unl.edu Thu Feb 8 19:36 EST 1996
Date: Thu, 8 Feb 1996 13:21:37 -0600
Message-Id: <199602081921.AA17275@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 414

Contents:
Successful drip irrigators (evan@griffith.dwr.csiro.au (Evan Christen))
(GroAire@aol.com)
Re: Recommendations for sub surface irrigation. (MEAD2513@aol.com)
Surfacing Problem? (storlie@AESOP.RUTGERS.EDU)
Re: Recommendations for SDI. (FLamm@oznet.ksu.edu (Freddie Lamm))
successfull drip irrigators (Jochen.Eberhard@t-online.de (Jochen Eberhard))
Regarding surfacing in SDI/alfalfa (Richard Mead <rmead@asrr.arsusda.gov>)
Root inhibitter dripper tape ("Marekesh (Pvt) Ltd" <marakesh@harare.iafrica.com>)
Re: Regarding surfacing (FLamm@oznet.ksu.edu (Freddie Lamm))

Date: Wed, 7 Feb 1996 18:35:56 -0600
From: evan@griffith.dwr.csiro.au (Evan Christen)
Subject: Successful drip irrigators

Hello all
In response to a highly critical report on drip irrigation in a popular
Australian paper, I am trying to get references to some long running
successful drip irrigation schemes in Australia. The failures listed in this
report were all from the early 80's, I would like to counter with some
successes.

Successful drip irrigation in cotton would be especially useful, may need
some help from the USA on that one.

If you know of long term successes please let me know, if possible the name
of the grower (I will contact them for permission to mention names), the
crops grown, the soil type and water saving compared to previous irrigation
system. The other claim in the article was that on heavy clay soils drip had
no water savings compared to well managed furrows. Any citable refs. to the
contrary gladly received or is it true...........?

Regards
Dr Evan Christen
Irrigation and Drainage Management for Horticulture
CSIRO Division of Water Resources
Griffith Laboratory
Griffith
NSW 2680
Australia
Tel # 61 69 601586
Fax # 61 69 601600

Date: Wed, 7 Feb 1996 22:21:44 -0500
From: GroAire@aol.com
Subject:

isten

The most successful drip irrigator on cotton in the U.S. that I know of is

Sundance Farms
Howard Wuertz
Coolidge, Arizona
Office 602-723-7711
Home 602-723-3788
Mobil 602-426-3449

Dave Enyeart
GroAire@aol.com

Date: Wed, 7 Feb 1996 23:19:20 -0500
From: MEAD2513@aol.com
Subject: Re: Recommendations for sub surface irrigation.

On Wed, 7 Feb 1996, Diana M Magarian <mille161@maroon.tc.umn.edu>
wrote: >The tubing is to be buried 2 feet
below the surface of the soil. The soil is at the site is a Hubbard
loamy sand (sandy, Udorothentic Haploboroll). Alfafla will be seeded on
the site<

I would be cautious at this depth (2 ft). We are wrapping up and experiment
with SDI in alfalfa on a heavy silt clay soil and our tubing is at
67-70cm deep (26-27.5 inches). We had it at 38 cm (15 inches)but
had surfacing problems (~3% of the area). However, since your soil is
a loamy sand, a 2 ft depth (60 cm) might be a tad bit TOO DEEP.

I assume you'll be sprinkling up the crop to get it established?
If so, keep the sprinklers going until you obtain a decent stand
and roots are at least 1 ft (30 cm) deep.

Richard Mead
Soil Scientist
Trickle-L owner/manager

Date: Thu, 08 Feb 1996 10:23:34 -0400 (EDT)
From: storlie@AESOP.RUTGERS.EDU
Subject: Surfacing Problem?

Richard Mead:

What is a "surfacing problem" in relation to a "too deep" sdi
installation?

I agree with you that a 24" installation in a loamy sand might be
too deep. However, water seems to jump to the surface in my 12" deep
sdi plots in sandy loams.

Craig Storlie
storlie@aesop.rutgers.edu

Date: 08 Feb 96 08:53:34 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Recommendations for SDI.

On Feb 7, Diana wrote

I need recommendations for what type, brand, etc. of irrigation material
we should use for an upcoming study. The tubing is to be buried 2 feet
below the surface of the soil. The soil is at the site is a Hubbard
loamy sand (sandy, Udorothentic Haploboroll). Alfafla will be seeded on
the site and it will be treated with 15N isotope solution, using the
irrigation system. Last year we conducted a study using Chapin drip tape
for surface application of the nitrogen solution, but I am not sure if
this can be buried. The main concern is uniformity, making sure each
plant ( which will be equally spaced) has equal opportunity to receive
the solution.
diana (e-mail-mille161@maroon.tc.umn.edu)

REPLY FROM F. LAMM
RICHARD MEAD HAS ALREADY REPLIED WITH SOME GOOD INFO. THE CHAPIN
DRIP TAPE AS WELL AS SEVERAL OTHER EXCELLENT BRANDS WILL WORK
SUBSURFACE. HOWEVER, IT IS GENERALLY RECOMMENDED THAT YOU USE A DRIP
TAPE OF 8 MIL OR HIGHER FOR SEMI-PERMANENT SUBSURFACE APPLICATIONS.
MOST OF THE TAPE MANUFACTURERS HAVE SEVERAL THICKNESSES.

MY LAST COMMENT HAS TO DO WITH YOUR CONCERN FOR UNIFORMITY. SDI
SYSTEMS CAN BE DESIGNED WITH A VERY HIGH DEGREE OF UNIFORMITY IN THE
DIRECTION OF THE LINE SOURCE. HOWEVER, BEING A LINE SOURCE, THEY
ARE INHERENTLY UNUNIFORM PERPENDICULAR TO THE DRIPLINE. IN FACT THIS
CHARACTERISTIC IS UTILIZED TO BE AN ADVANTAGE OF SDI, BEING ABLE TO
JUST SUPPLY WATER TO A REDUCED ROOTZONE. PROVIDING A UNIFORM WATER
DISTRIBUTION TO YOUR CASE OF ALFALFA ****MAY REQUIRE*** A FAIRLY
CLOSE LINE SPACING AND EMITTER SPACING. IT CAN BE DONE AND **MAY
PROVIDE** THE BEST IRRIGATION METHODOLOGY FOR YOUR EXPERIMENT, BUT
THAT MAY DEPEND ON YOUR NEED FOR UNIFORMITY AND YOUR REASONS FOR
SELECTING SDI IN THE FIRST PLACE.

GOOD LUCK.
FREDDIE
*

Date: Thu, 8 Feb 96 16:42 +0100
From: Jochen.Eberhard@t-online.de (Jochen Eberhard)
Subject: successfull drip irrigators

Hallo Evan,
I am not very successfull because I am on a research program for fertigation in
Germany. I don4t know the article you mentioned but the thing with the clay
sounds logical. The infiltration rate of this kind of soil is low compared to
that of a sandy soil, so the uniformity of furrow irrigation is relatively good.
On the other hand the water capacity of the clay soil is much higher than that
of a sandy soil, so you only flood the furrows once or twice a week, the soil
surface will be wet for only a few hours and evaporative losses of irrigation
water are small. Drip irrigation usually runs at least once a day the soil
surface is always wet - at least to a certain degree - and the losses through
evaporation will be high.

That4s what I think, but I never worked with furrow irrigation.

Jochen

Date: Thu, 8 Feb 1996 11:26:38 -0500
From: Richard Mead <rmead@asrr.arsusda.gov>
Subject: Regarding surfacing in SDI/alfalfa

Craig Storlie had mentioned >What is a "surfacing problem"
in relation to a "too deep" sdi installation?<

I guess I wasn't clear. We had surfacing problems with the shallower
depth of 15 in (38 cm) on that particular soil (silt clay).
With a crop like alfalfa, you don't want surfacing at all.
Upon going into the field for harvest or any cultural operation,
the tractor would encounter "wet spots" thereby damaging that area
almost permanently. Since we had these "wet spots" at 15 in (38 cm)
we decided to go deeper (~70 cm) and have since experienced no
surfacing at all. This allows one to irrigate while harvesting such that
regrowth is potentially faster.

Also, Craig, you had mentioned that >water seems to jump to the surface in
my 12" deep
sdi plots in sandy loams.<

How frequent do you irrigate? There is some controversy out in
SDI management land as to the importance of high frequency irrigations vs. long
irrigation sets. While I realize that applying 1 mm at a time is not feasible
on large fields, the concept of applying small doses several times per day
vs. one long set every other day will partially negate surfacing problems.
Some people call this technique "pulsing".
If one experiences surfacing continually, then I think the overall goal of
SDI has
been lowered.

SDI researchers such as Tim Hartz at UC Davis don't think much of the high
frequency approach. Maybe it is possible in this forum to establish
what the norm is, yet all this depends on the crop and soil type.

Richard Mead
Trickle-L owner/manager
Soil Scientist
USDA-ARS-WMRL

Date: Thu, 8 Feb 96 19:05 GMT+0200
From: "Marekesh (Pvt) Ltd" <marakesh@harare.iafrica.com>
Subject: Root inhibitter dripper tape

Rodney
A while ago Dave Eyeart asked if you had anything to do with the dripper
tape which is resistant to root intrusion. Please can you let me know if
this is correct or if you know of the company which supplies this tape.

My e-mail address is marakesh@harare.iafrica.com

Thanks Marek

Date: 08 Feb 96 11:33:23 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Regarding surfacing

Craig and Richard:
In bits and pieces of literature review I've done over the last few
years, I get the impression "surfacing" is analogous to a temporary
perching of a water table. Therefore, I would assume it is a problem
that is related to emitter application rate and soil hydraulic
conductivities. Better matching of application rates and event
times may help. I believe that "surfacing" is also referred to as a
"chimney" effect. I have heard colleagues refer to it as a bad
situation once it occurs and is difficult to remediate.

This has not been a problem in my setting, so perhaps my analogies
are not accurate. If so, those that know the specifics should correct
me.

Freddie
*

End of Digest
************************

From root@crcnis1.unl.edu Fri Feb 9 19:42 EST 1996
Date: Fri, 9 Feb 1996 13:22:08 -0600
Message-Id: <199602091922.AA11397@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 415

Contents:
critters chewing on drip tubes ("Bradley M. M. Smith (512) 245-7846" <BS09@a1.swt.edu>)
Re: critters chewing on drip tubes ("W. Bryan Smith" <WSMTH@prism.clemson.edu>)
surfacing vs. chimney effect in SDI (Richard Mead <rmead@asrr.arsusda.gov>)
Re: surfacing vs. chimney effect in SDI (cburt@oboe.aix.calpoly.edu (Charles M. Burt))
Re: Surfacing Problem? (GroAire@aol.com)
Re: critters chewing on drip tubes (GroAire@aol.com)
calcium sulphate levels (GroAire@aol.com)
Re: Surface Wetting with Buried Drip (dagoldhamer@ucdavis.edu)
Re: Surfacing Problem? (LodiCraig@aol.com)
Re: critters chewing on drip tubes (LodiCraig@aol.com)
Re: critters chewing on drip tubes (kluko@CyberGate.COM (Tim Parichan))
Simple Question (zachb@community.net (Zach Berkowitz))
Re: Simple Question ("W. Bryan Smith" <WSMTH@prism.clemson.edu>)
Re: Simple Question ("W. Bryan Smith" <WSMTH@prism.clemson.edu>)

Date: Thu, 08 Feb 1996 14:00:56 -0600 (CST)
From: "Bradley M. M. Smith (512) 245-7846" <BS09@a1.swt.edu>
Subject: critters chewing on drip tubes

I see from reading previous posts that many of the subscribers to
this list are agriculturists and that much of the discussion
pertains to underground systems. However, my problem is with
critters of some sort chewing holes in my above-ground drip
irrigation tubes. Perhaps someone has some information that may
help us.

Are they after normally looking for water or is this behavior
similar to squirrels chewing electrical lines in attics of houses?

I am the manager of a university grounds department in an area that
is VERY concerned with water conservation so drip irrigation will
probably be here to stay. Now we just need to find out how to keep
the critters away from it as much as possible.

Thanks,

Brad Smith
Southwest Texas State University
(over the Edwards Aquifer)

If you wish to respond directly, my address is bs09@swt.edu

Date: Thu, 08 Feb 1996 17:01:16 -0500 (EST)
From: "W. Bryan Smith" <WSMTH@prism.clemson.edu>
Subject: Re: critters chewing on drip tubes

Brad,
Sometimes the critters think the tube is something else. We've seen
crows attacking above ground drip before, thinking it was a black snake.

I guess it all depends on where you're looking from ....!

Bryan

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of
Clemson University or the Cooperative Extension Service.

Date: Thu, 8 Feb 1996 19:32:24 -0500
From: Richard Mead <rmead@asrr.arsusda.gov>
Subject: surfacing vs. chimney effect in SDI

Freddie,

Regarding your comment >I get the impression "surfacing" is analogous to a
temporary
perching of a water table. Therefore, I would assume it is a problem
that is related to emitter application rate and soil hydraulic
conductivities<

I agree in principle, but what about how long the irrigation system is on.
Doesn't this override
at least the emitter output aspect?

Also, regarding > I believe that "surfacing" is also referred to as a
"chimney" effect. I have heard colleagues refer to it as a bad
situation once it occurs and is difficult to remediate.<

My impression of chimney vs. surfacing are two different things.
Surfacing could entail "subbing" up water to germinate seedlings
like they do at Sundance farms in Arizona. I don't think this per se is referred
to as the "chimney" effect. However, the depth of drip tape at Sundance
is approximately 8 in. (20 cm). It is easier to "sub-up" at that depth.

I thought the chimney effect is when one can see actual flow of water with
sediment
moving out from a central "blow hole" (theoretically above the emitter).
Hence, imitating a chimney. Yes, you are correct at referring to the problem
as difficult to remediate.
Guys like Dr. C.J. Phene (SDI+) would say its all over and the system is ruined.
I don't know how valid that comment is in every incidence of the "chimney"
effect.

Drs. Charles Burt and David Goldhammer have done SDI research in Pistachios
and found mixed results. Both had surfacing problems (if you want to call it
a problem..
some don't). Dr. Goldhammer found less disease (on the nuts) in the SDI plots vs
traditional flood irrigation techniques due to lower humidity levels within
the tree canopy,
yet Dr. Burt found problems with surfacing which contributed to weed
problems. He doesn't think
SDI works well in this particular case.

Both Dr. Burt and Dr. Goldhammer are subscribers to Trickle-L and maybe they
could toss
in their comments on the particular studies and/or the surfacing-chimney
phenomena.

Richard Mead
Trickle-L owner/manager

Date: Thu, 8 Feb 1996 17:16:12 -0800
From: cburt@oboe.aix.calpoly.edu (Charles M. Burt)
Subject: Re: surfacing vs. chimney effect in SDI

Here are some quick comments:

1. SDI, as opposed to above ground drip, has an additional factor
influencing the Distribution Uniformity of the system - variations in soil
hydraulic conductivity. There will always be some "back pressure" on
buried emitters, so the discharge often cannot be precisely predicted based
on hose pressures - flow reductions of 5-10% are not unusual, although we
have not documented flow rate errors with shallow (6-10") buried tape on
row crops. We have, however, noted the chimneying effect on row crops as
well on trees and vines.

2. For many of our soils, there are tremendous infiltration problems
even with surface drip. In a conference in Visalia a few weeks ago there
was significant attention paid to this problem. Here at Cal Poly we
documented problems with low EC water, the use of ammonium fertilizers, and
improvements with calcium addition (as this impacts infiltration under
drip/micro) in the late 70's. Since then, there has been quite a bit of
research and experimentation and successful field implementation of related
practices over the years.

3. Now we get down to the chimneying effect. It's called a chimney
because the symptoms with buried drip are that you typically see a little
"volcanic dome" immediately above each emitter and there's plenty of water
on the soil surface.
This should not be surprising, given the fact that we have
historically had problems with drip infiltration on many soils.
The basic problem is that the low soil hydraulic conductivity
creates a saturated zone around the emitter. As the 3-D saturated (and
pressurized) ball around the emitter expands, eventually the spherical
surface area matches the area required/flow rate/hydraulic conductivity
combinations -- in theory. In practice, the hose was shanked in and when
that soil water is under pressure (several psi), it's pretty easy for it to
just move upward to the ground surface.
When you dig a out a trench, you will notice a vertical chimney
(perhaps 1 cm or less diameter) of almost pure sand extending from the
emitter to the ground surface - all of the fines have been washed away and
are piled up in the "volcanic dome" at the soil surface.
I have shared the same sense of futility that Claude Phene appears
to be expressing - we have had a tremendous problem with trying to
eliminate the chimneys once they show up. However, I haven't given up yet.
We have tried cultivation over the top of the hoses, gypsum injection,
pulsing, and some polymers - not very scientificially, I might add. We have
had great success with row crops, but not so good on trees and vines.
There's still a fair amount to learn.

We need to be cautious about saying that "there is no problem" in
some areas. Many of the SDI systems are on young trees or vines, where
there is very little ET yet, and therefore only a few hours of
operation/day. Ponding problems tend to increase with time rather than
decrease if they are related to water and soil chemistry. What I mean to
say is that it may take 2-4 years for a problem to show up.

A year and a half ago I spent about a week driving around
California just to see the extent of this problem. Virtually everywhere I
went, the problem showed up. In many cases I was told that there was no
problem, but when I went out to the orchard/vineyard, it existed -
sometimes severely.

Is it a serious concern? Maybe not - but if you still have a wet
soil surface, why spend the beau-coup extra bucks to put it underground?

Again - I am not writing off SDI for trees and vines - I am just
expressing a big note of caution. We need to recognize the problem and
learn if we can eliminate it - or at least learn where it will and won't
occur. In my opinion, we aren't very close to those answers yet.

Charles Burt
Irrigation Training and Research Center
Cal Poly
San Luis Obispo, CA 93407
cburt@oboe.calpoly.edu
(805) 756-2379

>Freddie,
>
>Regarding your comment >I get the impression "surfacing" is analogous to a
>temporary
>perching of a water table. Therefore, I would assume it is a problem
>that is related to emitter application rate and soil hydraulic
>conductivities<
>
>I agree in principle, but what about how long the irrigation system is on.
>Doesn't this override
>at least the emitter output aspect?
>
>Also, regarding > I believe that "surfacing" is also referred to as a
>"chimney" effect. I have heard colleagues refer to it as a bad
>situation once it occurs and is difficult to remediate.<
>
>My impression of chimney vs. surfacing are two different things.
>Surfacing could entail "subbing" up water to germinate seedlings
>like they do at Sundance farms in Arizona. I don't think this per se is
>referred
>to as the "chimney" effect. However, the depth of drip tape at Sundance
>is approximately 8 in. (20 cm). It is easier to "sub-up" at that depth.
>
>I thought the chimney effect is when one can see actual flow of water with
>sediment
>moving out from a central "blow hole" (theoretically above the emitter).
>Hence, imitating a chimney. Yes, you are correct at referring to the problem
>as difficult to remediate.
>Guys like Dr. C.J. Phene (SDI+) would say its all over and the system is
>ruined.
>I don't know how valid that comment is in every incidence of the "chimney"
>effect.
>
>Drs. Charles Burt and David Goldhammer have done SDI research in Pistachios
>and found mixed results. Both had surfacing problems (if you want to call it
>a problem..
>some don't). Dr. Goldhammer found less disease (on the nuts) in the SDI plots
>vs
>traditional flood irrigation techniques due to lower humidity levels within
>the tree canopy,
>yet Dr. Burt found problems with surfacing which contributed to weed
>problems. He doesn't think
>SDI works well in this particular case.
>
>Both Dr. Burt and Dr. Goldhammer are subscribers to Trickle-L and maybe they
>could toss
>in their comments on the particular studies and/or the surfacing-chimney
>phenomena.
>
>Richard Mead
>Trickle-L owner/manager

Date: Thu, 8 Feb 1996 20:39:18 -0500
From: GroAire@aol.com
Subject: Re: Surfacing Problem?

I can't answer for Richard, however I have seen surfacing problems or water
puddling on the surface. This was due to the permeability of the soil not
being matched to injection rate of the drip system. Alfalfa has an effective
4 foot root zone where 75% of the water is taken up by the plant. If this
surfacing becomes too chronic it can reduce yield or even kill the plant due
to anerobic conditions. Alfalfa does not like wet feet and is very suseptible
to over watering. I have seen alfalfa roots live in only two feet of soil
depth because of a high water table. The roots refuse to move down below that
2 foot mark.
Consequently, the yield is reduced because of the reduced root zone.

Dave Enyeart
GroAire@aol.com

Date: Thu, 8 Feb 1996 20:48:54 -0500
From: GroAire@aol.com
Subject: Re: critters chewing on drip tubes

By critters are you referring to mammals or insects?

Dave Enyeart
groAire@aol.com

Date: Thu, 8 Feb 1996 21:10:01 -0500
From: GroAire@aol.com
Subject: calcium sulphate levels

The Calcium sulphate levels(gypsum) are at such a high level in the Colorado
river water in Arizona that it is limiting crop production. Two methods of
treatment come to mind.

1. acid injection

2. chlorine injection

My question is this. What injection will cause the compound to precipitate
out and what mesh filter wouild be required to catch the precipitate. OR will
injection negate the need to filter for flood irrigation?

Dave Enyeart
Gr0Aire@aol.com

Date: Thu, 8 Feb 1996 19:37:10 -0800
From: dagoldhamer@ucdavis.edu
Subject: Re: Surface Wetting with Buried Drip

Fello and women,

As an introduction, I'm an Extension Water Management Specialist with the
University of California, Davis stationed at the Kearney Ag. Center in
Parlier (near Fresno). My research interest is primarily Regulated Deficit
Irrigation in tree fruit and nut crops. My group has conducted a couple
projects involving buried drip irrigation in pistachio. Both projects
evaluated the use of buried drip to reduce disease problems; Verticillium
Wilt (a soil borne fungus that invades roots) and Alternaria Alternata (a
leaf and nut fungus that causes shell staining and reduced shell
splitting). I won't go into the primary results of these studies; anyone
interested can contact me directly. Richard Mead asked me to make some
comments on surface wetting since we experienced that in both projects.

The first project was conducted in the western San Joaquin Valley on a
sandy loam soil with good hydraulic transport properties. The buried
treatments were at 30 and 60 cm. Emitters were 4 l/hr spaced 150 cm apart.
Two lines per tree row were shanked in about 120 from the tree row. The
trees were 2 years old when the project started and 6 years old at it's
conclusion. This work was conducted far from civilization so relatively
little "special" management was possible. The systems were operated
generally every day for as much as 3 hrs/day.

We experienced perfect surface wetting with the 30 cm depth; the wetted
pattern looked exactly as if the emitters were on the surface. With the 60
cm depth, we had no surface wetting throughout the project. Backhoe
investigations and neutron probe data showed quite dry soil in the top
10-15 cm of the soil. A large grower south of this site put in buried drip
at this depth (60 cm) last year and also had no surface wetting.

The second project was in a mature pistachio orchard with clay loam soil
with extremely poo60, and 75 cm with different flow rate emitters. All treatments resulted
in surface wetting but 2 l/hr emitters at 75 cm had the least. The regime
was installed in the project by shanking followed by flooding to settle the
soil. This regime was compared with border strip. Applied water amounts
were about the same. Surface wetting appeared immediately even though we
injected gypsum and tried pulsing the water.

Buried drip water movement differs fundamentally from surface application.
With surface, a poor transport soil results in the water moving overland
until it wets enough soil to allow for the total infiltration to equal the
application. That or the water ponds. With buried drip, poor hydraulic
transport limits the 3-D wetted area and the water moves under pressure
through the path of least resistance. This is the newly disturbed soil
above the emitter. Once the "chimney" develops, it's like having a pipe
connected to the emitter. I haven't found or heard of a good way to
destroying the "chimney" once it's established. The key is not letting the
"chimney" develop.

We are about to begin a buried drip project in Fig. Again, the idea is to
have a system that keeps the surface dry so that fruit dropping on the soil
is not exposed to an environment that encourages disease. The soil has
poor transport properties. We are going to install the tubing this summer
('96) but not run water through it until next summer. We will use the
existing surface drip this summer. This may allow the shanked soil to
consolidate over the winter to a more normal condition before we apply
water.

I should point out that surface wetting in tree crops results in the
following:

1) limited traffc access to the orchard,
2) increased weed problems, and
3) higher humidity levels.

If these are not important, then surface wetting is just an inconvenience.
I even heard that some growers like to see surface wetting because it
alerts them when the system is on and indicates whether line constriction
or root intrusion has occurred.

I should also point out that anyone installing a buried system should test
different placement depths and emitter flow rates before deciding on a
final regime. I varies tretape at 20-25 cm. Another walnut grower southwest of Modesto uses tubing
at 60 cm again with minimal surface wetting.

I'm optimistic about future use of buried drip on selected tree crops.
There's currently a lot of interest in it for pistachio and fig due
primarily to disease control. Other benefits would be gravy to these guys.

Dave Goldhamer
dagoldhamer@ucdavis.edu
209 891-2500
209 891-2593 (FAX)

Date: Thu, 8 Feb 1996 22:48:15 -0500
From: LodiCraig@aol.com
Subject: Re: Surfacing Problem?

Almost sounds like we may be getting into another terminology discussion. I
use the term 'surfacing' anytime my SDI applied water wets or puddles the
surface above the burried drip line.

We experienced surfacing across our entire installation in the year we
installed it. I attributed this to the water following the easiest path ...
along the ripper shank fracture line. The problem (as it encouraged weeds)
subsided somewhat as the season progressed. By the end of the third year,
the only circumstance in which we saw surfacing was following long
application times (over four hours in one shot) and in areas where the
tractors had 'puddled' the soil, thus destroying its structure.

I suspect three things are happening over time: 1. The easy path to the
surface is disappearing (hard pan in reverse, tillage creates a barrier above
the water source). 2. The roots of the grapevines are concentrating in
proximity of the emitters and pulling the water out nearly as fast as we are
applying it, and 3. The colliodial particles responsible for slowing
infiltration are being washed futher and further away from the emitters, thus
increasing the rate of infiltration around the emitters by creating a mostly
sandy pocket.

My seat of the pants substantiation of #3 above is that every year the hoses
show much less internal silt accumulation when flushing ... they're flushing
initially cleaner and clearing sooner as time passes.

Silt, or what ever the particle it is that makes the water brown, has always
been present at startup, but has never effected flow. It is most pronounced
on the high end of the field following extended rains or long irrigations. I
attribute it to free water in the soil re-entering the hose via the emitters
and flowing down slope (.012) till it settles in the hose ... only to be
flushed out the ends at startup.

Are my 'suspicions' confirmed by others' experience or research?

Craig Thompson, Lodi, CA

Date: Thu, 8 Feb 1996 22:48:33 -0500
From: LodiCraig@aol.com
Subject: Re: critters chewing on drip tubes

In a message dated 96-02-08 15:14:59 EST, you write:
> However, my problem is with
> critters of some sort chewing holes in my above-ground drip
> irrigation tubes. Perhaps someone has some information that may
> help us.
>
> Are they after normally looking for water or is this behavior
> similar to squirrels chewing electrical lines in attics of houses?

Yup. We have more problems with our above ground drip for this very reason.

It would be helpful if you could tell us what kinds of critters are common in
your area. Around here we have problems with coyote pups during teething.
On thing that helps is to leave scraps of hose littered around the affected
area ... they seem to take them 'home' and quit bothering the real hose.
Skunks also seem to take a bite now and again.

It came up earlier on Trickle-L, and confirmed in our installations, that
when we have stretched hose across their habitual trails, they protest by
continually chewing on the new obstruction ... this seems to only last a
season or two.

In our experience, the longer the installation has been in place, the less
they seem to bother it. Critters were expecially attracted to our bright
orange flush caps on the end of our SDI ... they even seem to be growing
bored with those now.

Craig Thompson, Lodi, CA

Date: Fri, 9 Feb 1996 13:31:28 GMT
From: kluko@CyberGate.COM (Tim Parichan)
Subject: Re: critters chewing on drip tubes

Brad Smith
Southwest Texas State University wrote

> I see from reading previous posts that many of the subscribers to
> this list are agriculturists and that much of the discussion
> pertains to underground systems. However, my problem is with
> critters of some sort chewing holes in my above-ground drip
> irrigation tubes. Perhaps someone has some information that may
> help us.
>
> Are they after normally looking for water or is this behavior
> similar to squirrels chewing electrical lines in attics of houses?

We have an increase in damage from ground squirrels every time
we shut off the water for an extended lenght of time. This is
especially annoying during harvest. We have spent considerable
effort in the last few years trying to get rid of the ground
squirrels, but they alwys seem to find their way back. As was
noted in earlier posts, it would help to know what critter is
actually doing the chewing in order to establish a plan. There
are some publications on Vertbtrate pest management that can be
helpful, especially since each critter has its own peculiararities.

The Grateful Dead - It's kinda like that fluffy blanket you had as a child.
It always felt good.

Date: Fri, 9 Feb 1996 07:34:15 -0800
From: zachb@community.net (Zach Berkowitz)
Subject: Simple Question

In the vineyards in Northern California the two principal methods of
irrigation are solid set sprinklers and drip. Most methods for determining
how much to irrigate result in a volume in inches or mm. This is pretty
intuitive for sprinkler irrigation but less so for drip. To settle an
argument, how do you get from mm to gallons or liters per vine?

Camp A says you take the mm of water and convert it to liters, add an
efficiency factor and divide by the number of vines or emitters.

Camp B says you do the same as above but factor in the effective wetted
zone. This gives you a smaller volume of water, e.g. if each vine takes up
4 sq m of surface area and the wetted area is 1 sq m, only 25% of the
surface is actually getting irrigated so the volume should be 25% of the
calculated volume.

Which approach is more accurate and/or is there a alternative method that
is more accurate? Obviously this is a critical question because the amount
of supplimental irrigation can be calculated or measured to precise volumes
but based on the conversion to liters per vine, the volume can change
dramatically.

==============================================
Zach Berkowitz
Domaine Chandon, POBox 2470, Yountville, CA 94599
(707) 944-8844, (707) 944-1123 (Fax)
zachb@napanet.net
zachb@community.net
==============================================

Date: Fri, 09 Feb 1996 11:39:12 -0500 (EST)
From: "W. Bryan Smith" <WSMTH@prism.clemson.edu>
Subject: Re: Simple Question

Zach,
Group A's idea is basiaclly one of:
(1) Determine the maximum water need of each plant
(2) Calculate plants per acre
(3) Determine gallons per acre required and application
efficiency
(4) Apply said water.

Group B's idea is similar, but adds:
(1) Divide (4) by actual wetted area

Not a good idea. Your intent is to get all the water the plant needs to the
plant, not apply water based on how large an area is irrigated.

Probably the best method is to design like Group A mentions, then actually
irrigate using some sort of soil moisture-sensing system to help schedule
irrigation events. See the discussions we have had previously on this list
abour moisture sensing equipment.

I'd be interested to hear other design philosophies on this subject.

Bryan

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of
Clemson University or the Cooperative Extension Service.

Date: Fri, 09 Feb 1996 11:42:00 -0500 (EST)
From: "W. Bryan Smith" <WSMTH@prism.clemson.edu>
Subject: Re: Simple Question

And on re-readng I missed the question! Sorry! I'd use group B's idea
if I had a good idea of the actual surface area affecting the plant. This
should include some area outside the root zone to account for lateral water
movement into the root area as water is removed.

Bryan

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of
Clemson University or the Cooperative Extension Service.

End of Digest
************************

From root@crcnis1.unl.edu Sat Feb 10 19:33 EST 1996
Date: Sat, 10 Feb 1996 13:22:43 -0600
Message-Id: <199602101922.AA24269@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 416

Contents:
Re: Simple Question (M D Greenspan <mdgreenspan@ucdavis.edu>)
Question ? surfacing by way of chimney (Louis Baumhardt <r-baumhardt@tamu.edu>)
Re: Simple Question ("Gary Clark" <GCLARK@falcon.age.ksu.edu>)
Re: Question ? surfacing by way of chimney (cburt@oboe.aix.calpoly.edu (Charles M. Burt))
Re: Simple Question (JRobb209@aol.com)

Date: Fri, 9 Feb 1996 13:10:32 -0800
From: M D Greenspan <mdgreenspan@ucdavis.edu>
Subject: Re: Simple Question

Zach:

My vote goes to camp A. Camp B assumes, incorrectly, that water is
evaporated/transpired equally from all points of the land surface and
therefore, we should replace only the fraction represented by the area of
the wetted zone. But since most of your soil surface is perpetually dry,
the primary source of ET is the vines. But ET estimates will be
spatially-averaged over the field, even though we are "pumping" the water
from discrete wetted areas (plus, of course, stored water from rainfall
and water table)

Camp B would under-irrigate the vines.

The efficiency factor, I assume, relates to either distribution
nonuniformity, soil surface evaporation, or deep percolation losses. I
would think that the first would be the primary concern, although some loss
could occur from a wetted soil surface. But the latter could be minimized
by proper scheduling. Anyway, that wasn't the crux of the question...

Mark

----
Mark D. Greenspan
Dept. of Viticulture & Enology
Dept. of Biological and Agricultural Engineering
U.C. Davis
mdgreenspan@ucdavis.edu

Date: Fri, 09 Feb 1996 15:53:14 -0600
From: Louis Baumhardt <r-baumhardt@tamu.edu>
Subject: Question ? surfacing by way of chimney

Water surfacing by way of chimney effect sounds like a form of
channelized flow. I guess it is like fingering flow upwards.

Anyway, I need to catch up on this one.

Since alot of you seem to be familiar with "surfacing-chimney style"
could you direct me to your favorite journal article documenting it.

Thanks!!

R. Louis Baumhardt
Texas Agric. Exp. Station
Lubbock, TX 79401-9757
r-baumhardt@tamu.edu

Date: Fri, 9 Feb 1996 16:27:29 CST
From: "Gary Clark" <GCLARK@falcon.age.ksu.edu>
Subject: Re: Simple Question

Dear Mr. Berkowitz,

The atmospheric water demands or requirements on the crop are
distributed over the crop surface. However, the water reservoir from
which the plant(s) are extracting water is the irrigated root zone
which can be expressed as a soil volume. From a sprinkler irrigation
standpoint the depth of application approach is very logical.
However, drip irrigation applies water in volumetric units such as xx
liters per hour per dripper and generally results in discrete volumes of
irrigated soil for each dripper, group of drippers, etc. Thus,
express the water requirements of the crop in volumetric units
consistent with the irrigation water delivery system. That volume
of irrigated soil can hold just so much water based upon its water holding
chracteristics. Once that volume of "available water has depleted to
the MAD (management allowed deficit), then that volume of water
should be replaced. The relationship between the volume of water
associated with the MAD for the irrigated root zone and that of the
crop ET requirements will determine the frequency of irrigation which
may be several cycles per day or several days between cycles
(depending on soil and crop irrigated root zone properties).

Good luck.

Gary A. Clark
******************************************
Gary A. Clark, P.E.
Associate Professor
Biological and Agricultural Engineering
147 Seaton Hall
Kansas State University
Manhattan, KS 66506-2906
Tel: 913-532-5580
Fax: 913-532-5825
******************************************

Date: Fri, 9 Feb 1996 15:13:27 -0800
From: cburt@oboe.aix.calpoly.edu (Charles M. Burt)
Subject: Re: Question ? surfacing by way of chimney

The problem is described and discussed in

Chapter 20 of:

Drip and Microirrigation for Trees, Vines, and Row Crops (with special
sections on buried drip).
by Charles Burt and Stuart Styles
1994
ISBR 0-9643634-0-2
Published by the
Irrigation Training and Research Center
Cal Poly
San Luis Obispo, CA 93407
(805) 756-2434

>Water surfacing by way of chimney effect sounds like a form of
>channelized flow. I guess it is like fingering flow upwards.
>
>Anyway, I need to catch up on this one.
>
>Since alot of you seem to be familiar with "surfacing-chimney style"
>could you direct me to your favorite journal article documenting it.
>
>Thanks!!
>
>R. Louis Baumhardt
>Texas Agric. Exp. Station
>Lubbock, TX 79401-9757
>r-baumhardt@tamu.edu

Date: Sat, 10 Feb 1996 02:27:37 -0500
From: JRobb209@aol.com
Subject: Re: Simple Question

Mr. Berkowitz,
May I expand on Gary Clark's comment. Generally, you would have a crop water
use depth (mm) from some crop ET calculation. The depth is a volume
measurement that assumes a reference to the complete field soil surface, not
just the vegetatively covered soil surface, so the ET estimate is dependent
on specific cultural contitions. Assuming that these conditions match your
cultural contitions, the crop ET demand is the amount of water removed from
the wetted rootzone.

Since the wetted rootzone with drip is seldom 100 percent of the field soil
surface, the reference for a depth of crop water demand is not the same as
for soil moisture removal. The solution is to pick a common field soil
surface unit and convert to a volume. This unit can be the surface for a
single tree(field size/# of trees, or calculate the plant spacing area) or
say, use the whole field to get something that matches a water meter reading.
Convert the depth to cubic something to gallons or liters. Divide by the
total gallons(or liters) per hour applied by all of the emitters within the
unit area to get the system run required for a 100% uniform system. Divide
by the uniformity to get actual system run time.

Mr. Clark points out that you need to irrigate again before the MAD is
reached. If the amount applied for any event is greater than the rootzone
can hold, you will loose water out the bottom. More frequent and lesser run
time irrigations are necessary if this occurs. The MAD depth must be
multiplied by the active rooting percentage, typically the wetted percentage,
to determine the depth of water that will refill the profile.

If the system is operated in a high frequency manner the MAD value and soil
water holding capacity are not particularly important, just matching the
demand. This may be more than you wanted, but I thought that I would put my
two cents in.

Jerry Robb, jrobb@aol.com.

End of Digest
************************

From root@crcnis1.unl.edu Sun Feb 11 19:36 EST 1996
Date: Sun, 11 Feb 1996 13:23:17 -0600
Message-Id: <199602111923.AA03155@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 417

Contents:
Re: Simple Question (Trevor Finch <rsne@mpx.com.au>)
Re: Simple Question (LodiCraig@aol.com)

Date: Sun, 11 Feb 96 11:15:20 +1100 (EST)
From: Trevor Finch <rsne@mpx.com.au>
Subject: Re: Simple Question

I agree with Jerry Robb

If the plant is using "5mm/day" then every 10 days the plant will use 50mm.
But we need a volume to replace this water, so we have to multiply by an area.

If there is a wetted area of, say, 50%, then the actual soil area that can
contain water is only 50% of the total area. So the volume to apply must be
calculated using the wetted area. If you apply more than this (based on
total area), water will presumably be draining through the profile, or
waterlogging is giving anerobic conditions.

There is a similar problem with large, discrete, plants (such as trees),
even with uniform water application.
It is only by assuming that plants are sufficiently close together can we
assume essentially vertical flow in any calculations.

But the important questions - *are* the plants using 5mm/day ? What *is*
the wetted area ? Is there through-drainage or water logging ?

When an agronomist says this plant (stem, tree) uses 5mm/day what do they mean ?

If the 5mm/day has come from a lysimeter then it is rate-of-change of total
water content on the weighbridge.
But if it has come from sap flow measurements, has it been calculated by
dividing total water through the stem (it must be in volume) by 1 The
area per plant or 2 The wetted area ?

But how much water is this plant, in this field, this year, actually using ?

If soil water content is measured close to a dripper, there might be no
change at all during a cycle. If measured mid-way between drippers, there
might also be no change. At the 'magic' distance there will be a
representative rate of change. From trials in grapes in the Napa valley to
find this 'magic' distance the general practical conclusion seems to be to
measure at the quarter point.

In addition, measurements from commercial growers show that the wetted area
varies with soil type and plant, but also varies significantly during a
season. That is, the amount of water that a soil can hold, and the root
extraction pattern, varies with time.

But to calculate total volumes from soil moisture measurements - I wasted a
long time with 3-dimensional geometry - and got the practical soluion from
agronomists in the real world.

Take measurements at a 'magic' distance from the stem (the quarter point -
where there are changes), and watch both the rate of change and the
condition of the crop.

Make the decision *when* to irrigate based on the crop condition and rate of
change of soil moisture. (we call this soil water content the 'refill
point' - the soil water content at which irrigation of *this* field should
take place)

The *amount* to apply should then be 'sufficient water to bring the soil
moisture reading back to the full point' (but not over). Turn the pumps on,
and wait till the soil measurements come back to the full point (allow for
time delays, of course).
In practice, water scheduling orders will need to be in time or volume, but
after a few irrigation cycles there will be a relationship between mm
deficit in the soil measurments in this field and pumping time.

The 'rate of change' of the measuring point might not be giving a 'true'
stem mm/day, but it is giving a 'marker'

The general conclusion from agronomists working in many countries is that,
in practice, three profiles should be measured in each water management unit
to get a representative measurement.

Incidentally, if you take measurements that *are* representative of the
total area, then:

Water_efficiency =(total volume applied/total gain of the profile)

It can be more than 100%, and:

Wetted_Area = Total_Gain/Total_Applied = 1/Efficiency

You can calculate wetted areas from measuments. The smaller the wetted
area, the higher the efficiency .

Drippers are efficient...

----
Trevor Finch
Research Services New England
23 Vincent St, Balmain NSW 2041 Australia
tel +61 (2) 810 3563
fax +62 (2) 818 3617

Date: Sun, 11 Feb 1996 02:37:08 -0500
From: LodiCraig@aol.com
Subject: Re: Simple Question

Hi gang!

Seems I read a lot of technical answers ... isn't it simpler than that?

>In the vineyards in Northern California the two principal methods of
>irrigation are solid set sprinklers and drip. Most methods for determining
>how much to irrigate result in a volume in inches or mm.

O.K. We are defining the problem to vineyards. Most research I am familiar
with also assumes that 1.) the irrigations are scheduled to avoid deep
drainage,2.) and right or wrong surface application loss to evaporation is
generally ignored or considered inconsequential. 3.)Loss to cover crop or
weeds is calculated seperately so the presumption is a clean vineyard (add in
cover crop consumption seperately).
4.) Consumptive figures are corrected by a foliage factor, not vines per
acre, generally considered to be two times the percentage of soil shadowed by
foliage at noon.

> This is pretty
>intuitive for sprinkler irrigation but less so for drip. To settle an
>argument, how do you get from mm to gallons or liters per vine?

What are there, is it 352,000 gallons per acre foot? Assuming this:

mm x 352,000 gallons/acrefoot
gallons/vine =

254 mm/inch x 12 inches/foot x ? vines/acre

>Camp A says you take the mm of water and convert it to liters, add an
>efficiency factor and divide by the number of vines or emitters.

I believe it is as simple of this. Other factors are cancelled out by the
presumptions in the source of the data you are comparing to. I think
sprinkler and furrow are equivalent efficiency, above ground drip needs 90%
for similiar results, and SDI around 85%. My numbers are seat of the pants
stuff. (IMHO SDI's efficiencies come from fertigation and control, not water
'savings'). Distribution uniformity assumed the same here.

>Camp B says you do the same as above but factor in the effective wetted
>zone. This gives you a smaller volume of water, e.g. if each vine takes up
>4 sq m of surface area and the wetted area is 1 sq m, only 25% of the
>surface is actually getting irrigated so the volume should be 25% of the
>calculated volume.

Not for total consumption, but for soil storage capacity. Vines will consume
essentially the same, but you gotta irrigate more often.

Hope this helps answer your question,
Craig Thompson, Lodi, CA

End of Digest
************************

From root@crcnis1.unl.edu Mon Feb 12 19:57 EST 1996
Date: Mon, 12 Feb 1996 13:44:28 -0600
Message-Id: <199602121944.AA21689@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 418

Contents:
Re: Drip/Furrow Irrig.of Pistachios (geoflow1@slip.net (Rodney Ruskin))
Re: Simple Question (tahowell@ag.gov)
Re: Simple Question (tahowell@ag.gov)
Re: Simple Question (tahowell@ag.gov)
Simple question/sap flow sensors (evan@griffith.dwr.csiro.au (Evan Christen))
Simpler Question (zachb@community.net (Zach Berkowitz))
Re: Simpler Question ("M. Meron" <MERON@migal.co.il>)
Simple question/sap flow sensors -Reply ("Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>)
simple question (Jochen.Eberhard@t-online.de (Jochen Eberhard))
Re: Simple Question (tahowell@ag.gov)
Surfacing response to R. Mead and L. Baumhardt (FLamm@oznet.ksu.edu (Freddie Lamm))

Date: Sun, 11 Feb 96 12:01 PST
From: geoflow1@slip.net (Rodney Ruskin)
Subject: Re: Drip/Furrow Irrig.of Pistachios

At 9:42 AM 2/6/96 -0600, Thomas-M. Stein wrote:
>Dear Colleagues,
>
>Our Department is conducting an irrigation research project on
>pistachios under drip irrigation in Iran.
>
>We are comparing drip irrigation with the traditional furrow
>method. We also altered the traditional scheduling using a class
>A-pan and applying water on a rate of 0.6, 0.8, 1.0 and 1.2 times
>the reading of the class A-pan.
>
>So far the results have been promising. Even drip irrigation
>strongly increased vegetative growth, at the same time the yield
>and quality seem to be positively affected as well.
>
>We would greatly appreciate any information on similar
>experiences with drip irrigated pistachios or some useful
>references.
>
>Any hint will be appreciated
>
>Yours sincerely
>
>Dr. Peter Wolff (wolff@wiz.uni-kassel.de)
>Thomas Stein (stein@wiz.uni-kassel.de)
>

There have been excellent large scale commercial results with SDI on
pistachios - unfortunately the data is private and confidential. The U.S.
growers consider Iran a serious competitor so it is not be possible to get
permission to publish anything.
So I will only repeat my constant message: High frequency SDI plus pulsing
plus precise management = super results in both yield and quality.
Pistachios are not an exception.

Also see the work by Dr. Goldhamer, which is published:

Dr. David Goldhamer
Kearney Agricultural Research Station,
9240 South Riverbend Ave.
Parlier CA 93648.

Regards,

Rodney Ruskin.

Date: Sun, 11 Feb 96 16:08:56 MST
From: tahowell@ag.gov
Subject: Re: Simple Question

Trickle-L:

If possible, I would like to get a few cents into the discussion of
the "simple question." It's obvious there's no such thing as a
'simple' question nor a 'simple' answer!

My vote goes to Camp C (which assumes both Camps A and B are
incorrect). In Camp C, I would recommend either 1)'slightly'
underirrigating according to either A or B and monitoring plant
response (visually or perhaps more direct responses like LWP with a
pressure bomb or crop temperature with an IRT) and increase irrigation
to alleviate crop water water stress while monitoring soil water
status or 2) (my actual preference) 'slightly' over-irrigating by A
and watching soil water contents (when the soil seems 'too' wet, then
reduce the application rate) while monitoring plant water staus to
make sure of not under-irrigating. This involves measuring soil
factors and plant factors as well as knowing (or more correctly
presuming) what ET may be. Jerry Robb's and Gary Clark's comments and
those from many others are largely correct, but I'm still convienced
until we use all our available "information" we will not succeed!

Hopefully, those doing irrigation research on horticultural crops with
drip will eventually have enough data on plant water consumption (not
ET) to use this volumetric data with scheduling programs based on
volumes/unit area (depths). Lysimeters can partially answer the
question since they measure the volumetric consumption of water (water
volume/plant). Also sap flow gauges can provide a direct measure of
plant volumetric consumption. The correct 'translation' of ET
information from a depth based system (volume/unit area) to a
volumetric system (volume/plant) is clearly not SIMPLE!

Terry Howell

*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 *
* USDA-ARS (806) 356-5750 (Fax) *
* P.O. Drawer 10 tahowell@ag.gov (E-mail) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* *
* 1/2 mi. West I-40 South Access Rd. (shipping) *
*********************************************************************

Date: Sun, 11 Feb 96 16:09:51 MST
From: tahowell@ag.gov
Subject: Re: Simple Question

Trickle-L:

If possible, I would like to get a few cents into the discussion of
the "simple question." It's obvious there's no such thing as a
'simple' question nor a 'simple' answer!

My vote goes to Camp C (which assumes both Camps A and B are
incorrect). In Camp C, I would recommend either 1)'slightly'
underirrigating according to either A or B and monitoring plant
response (visually or perhaps more direct responses like LWP with a
pressure bomb or crop temperature with an IRT) and increase irrigation
to alleviate crop water water stress while monitoring soil water
status or 2) (my actual preference) 'slightly' over-irrigating by A
and watching soil water contents (when the soil seems 'too' wet, then
reduce the application rate) while monitoring plant water staus to
make sure of not under-irrigating. This involves measuring soil
factors and plant factors as well as knowing (or more correctly
presuming) what ET may be. Jerry Robb's and Gary Clark's comments and
those from many others are largely correct, but I'm still convienced
until we use all our available "information" we will not succeed!

Hopefully, those doing irrigation research on horticultural crops with
drip will eventually have enough data on plant water consumption (not
ET) to use this volumetric data with scheduling programs based on
volumes/unit area (depths). Lysimeters can partially answer the
question since they measure the volumetric consumption of water (water
volume/plant). Also sap flow gauges can provide a direct measure of
plant volumetric consumption. The correct 'translation' of ET
information from a depth based system (volume/unit area) to a
volumetric system (volume/plant) is clearly not SIMPLE!

Terry Howell

*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 *
* USDA-ARS (806) 356-5750 (Fax) *
* P.O. Drawer 10 tahowell@ag.gov (E-mail) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* *
* 1/2 mi. West I-40 South Access Rd. (shipping) *
*********************************************************************

Date: Sun, 11 Feb 96 16:11:43 MST
From: tahowell@ag.gov
Subject: Re: Simple Question

Trickle-L:

If possible, I would like to get a few cents into the discussion of
the "simple question." It's obvious there's no such thing as a
'simple' question nor a 'simple' answer!

My vote goes to Camp C (which assumes both Camps A and B are
incorrect). In Camp C, I would recommend either 1)'slightly'
underirrigating according to either A or B and monitoring plant
response (visually or perhaps more direct responses like LWP with a
pressure bomb or crop temperature with an IRT) and increase irrigation
to alleviate crop water water stress while monitoring soil water
status or 2) (my actual preference) 'slightly' over-irrigating by A
and watching soil water contents (when the soil seems 'too' wet, then
reduce the application rate) while monitoring plant water staus to
make sure of not under-irrigating. This involves measuring soil
factors and plant factors as well as knowing (or more correctly
presuming) what ET may be. Jerry Robb's and Gary Clark's comments and
those from many others are largely correct, but I'm still convienced
until we use all our available "information" we will not succeed!

Hopefully, those doing irrigation research on horticultural crops with
drip will eventually have enough data on plant water consumption (not
ET) to use this volumetric data with scheduling programs based on
volumes/unit area (depths). Lysimeters can partially answer the
question since they measure the volumetric consumption of water (water
volume/plant). Also sap flow gauges can provide a direct measure of
plant volumetric consumption. The correct 'translation' of ET
information from a depth based system (volume/unit area) to a
volumetric system (volume/plant) is clearly not SIMPLE!

Terry Howell

*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 *
* USDA-ARS (806) 356-5750 (Fax) *
* P.O. Drawer 10 tahowell@ag.gov (E-mail) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* *
* 1/2 mi. West I-40 South Access Rd. (shipping) *
*********************************************************************

Date: Sun, 11 Feb 1996 20:28:38 -0600
From: evan@griffith.dwr.csiro.au (Evan Christen)
Subject: Simple question/sap flow sensors

I was interested in Terry Hills comments of assessing actual water use not
just ET:.........
"Hopefully, those doing irrigation research on horticultural crops with
drip will eventually have enough data on plant water consumption (not
ET) to use this volumetric data with scheduling programs based on
volumes/unit area (depths). Lysimeters can partially answer the
question since they measure the volumetric consumption of water (water
volume/plant). Also sap flow gauges can provide a direct measure of
plant volumetric consumption. The correct 'translation' of ET
information from a depth based system (volume/unit area) to a
volumetric system (volume/plant) is clearly not SIMPLE!"..............

I believe the work with sap flow sensors on grapevines and citrus here in
Australia indicates that the actual plant water use may be only 30% of the
calculated ET. This must mean we are calculating ET incorrectly or that the
direct evaporation components are the major part of ET or this could be
rationalised by saying that the non-uniformity of irrigation appication,
root distribution, soil texture and structure are such that ET is an
averaging on a paddock scale of all factors and thus it cannot be compared
to actual individual plant water use? Agree/disageree?

If plant water use is as low as the early results show then water use
efficiency has even futher to go!
Dr Evan Christen
Irrigation and Drainage Management for Horticulture
CSIRO Division of Water Resources
Griffith Laboratory
Griffith
NSW 2680
Australia
Tel # 61 69 601586
Fax # 61 69 601600

Date: Sun, 11 Feb 1996 22:04:35 -0800
From: zachb@community.net (Zach Berkowitz)
Subject: Simpler Question

Earlier I posed a question about getting from a given irrigition
requirement in mm to gallons or liters per vine under drip irrigation. Do
you convert mm to gallons/liters or factor in the wetted area under the
emitters? I got some answers for a simple conversion, some for a wetted
area factor and some I couldn't that, well, I couldn't tell. Perhaps I can
restate the question a little differently with some specifics:

ETc = 10mm and there are 10,000 vines spaced 2 meters by 3 meters in an
irrigation block, each with a 4 liter per hour emitter. The effective soil
depth is 1 meter and 25% of the total soil volume gets wetted during an
irrigation. How long should the irrigation set last to replace the 10mm
(forget about evaporation and other losses and assume that crop factors are
correct)?

The surface area is 60,000 square meters
The irrigation rate is 40,000 liters per hour

One answer is to convert 10mm to liters to irrigation duration: 10mm x
60,000m2 = 600 m3 = 600,000 liters = 15 hours

Another answer is to multiply the water use by the 25% being wetted: 10mm
x 60,000m2 x 0.25 = 150 m3 = 150,000 liters = 3.75 hours

Which, if either of these answers in correct. I am looking for the
conceptually right answer. As one approach yields an irrigation four times
the other one, this is an important concept to understand!

==============================================
Zach Berkowitz
Domaine Chandon, POBox 2470, Yountville, CA 94599
(707) 944-8844, (707) 944-1123 (Fax)
zachb@napanet.net
zachb@community.net
==============================================

Date: Mon, 12 Feb 1996 09:06:58 GMT+0200
From: "M. Meron" <MERON@migal.co.il>
Subject: Re: Simpler Question

The simple answer to simple question is 15 hours.

You can look at this differently:

- Your application rate is: 4 l/h over (2x3) 6 sq.meters = 2/3 mm/hour.
- Then 10 mm irrigation will take 10/(2/3) = 15 hours.

If the water consumption of the crop is 10 mm (10 liter/sq.meter of
full field area) indeed.

There is nothing to do with the wetted volume. The basic principle of
drip and other tipes of miciro-irrigation is that roots will take up the
entire water consumption of the crop from a smaller wetted volume just as
well as from a flooded field. Instructions in the form of liter/vine or
liter/tree is a back translation of per-area water consumption for
sparsely spaced horticultural crops.

As for how much, how often, ETp, ETc, Kc, etc... the ongoing conversation
is quite thorough and you can also consult your farm advisor or maybe the
CIMIS people in Sacramento.
=========================================================================
MIGAL Galilee Technology Center Crop Ecology Laboratory
Kiryat Shmona PO Box 90 000 Rosh Pina 12 100 ISRAEL
Phone +972-6-953559 Fax: +972-6-944980 Email: MERON@migal.co.il
=========================================================================

Date: Mon, 12 Feb 1996 9:37:45 +200
From: "Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>
Subject: Simple question/sap flow sensors -Reply

TRICKLE-L
I don't want to side-track the very interesting discussion that
is developing, but to respond to Dr Evan Christen's questions:

.. "I believe the work with sap flow sensors on grapevines and
citrus here in Australia indicates that the actual plant water
use may be only 30% of the calculated ET. This must mean we are
calculating ET incorrectly or that the direct evaporation
components are the major part of ET or this could be rationalised
by saying that the non-uniformity of irrigation appication, root
distribution, soil texture and structure are such that ET is an
averaging on a paddock scale of all factors and thus it cannot be
compared to actual individual plant water use? Agree/disageree?

If plant water use is as low as the early results show then water
use efficiency (WUE) has even futher to go! "....

The possibility that direct (non-plant) evaporation may be the
dominant water loss in an irrigated vine situtation sounds
entirely plausable given the ratio of bare soil to crop from what
I have seen.

However, I want to reply to the last point on our estimations of
WUE by bringing up my favourite argument - that of the definition
of WUE.

>From a newsletter atricle I published recently, I would like to
include the following extract: (It is written about rain-fed
plantations, but the arguments still hold).

"For this discussion, we will define two terms: a Rainfall Use
Efficiency (RUE) and a Water Use Efficiency (WUE). RUE can be
defined as a measure of the amount of timber yield obtained
relative to the amount of rain [or irrigation] that the area
received over the rotation length. So if 200 m3 of timber grew
over 8 years with 7200 mm of rainfall, then it would have a RUE
of 200/7200=0.0278 m3/mm. Factors such as excessive runoff, steep
slopes, etc. due to soil characteristics, will reduce the
fraction of rainfall that enters the soil and so is available to
the tree. (For a comparison across sites, we will assume these
factors constant). For a given gross rainfall, the RUE takes into
account how much of that rainfall that finally becomes available
to the tree can be made use of by the tree. What it does not take
into account is the efficiency with which the transpired water is
used.

Strictly speaking, the water use efficiency (WUE) is the ratio of
carbon assimilated per unit water *transpired*. For our purposes
this may be simplified to the amount of water required by the
tree to put on a unit of growth. Those trees adapted to dry
conditions generally use less water per unit growth, but grow at
a slower rate even when water becomes abundant. At the other
extreme are the rainfall use-efficient trees - those that are
adapted to higher rainfalls. They are not used to "saving" water,
and thus often [but not always] have a low WUE, despite being
better able to take up large amounts when it is there. They
probably suffer far sooner at the onset of water limitations, and
so will have a far greater mortality than slower growers.

However, rainfall use efficent trees do not necessarily have a
low WUE. And water use efficient trees are, likewise, not always
poor at making use of all the available rainfall. blab blab,
etc. etc. ..."

So what I am saying, is that ignoring the skill of the irrigation
scheduler (shall we, er, assume perfection here?!?), the amount
of crop product produced per unit water applied and that per unit
water transpired are two different things.

We need to recognize this and make the distinction.

Having had my say, I have not contributed much to answering the
questions asked.

(Email me if you would like to recieve the full article, or get
in contact re WUE measurements).
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.
Bruce Metelerkamp SOIL WATER RESEARCH OFFICER
Institute for Commercial Forestry Research,
University of Natal, PO Box 100281
Scottsville, ZA3209
Rep. of South Africa Voice:27 331 62314
E-mail: bruce@icfr.unp.ac.za FAX:27 331 68905
URL http://www.icfrnet.unp.ac.za/~metele

Date: Mon, 12 Feb 96 13:25 +0100
From: Jochen.Eberhard@t-online.de (Jochen Eberhard)
Subject: simple question

The question is simple but the answer is not.
First of all you cannot apply 600 m3 water to 25% of the area, you will have 40
mm put on the soil.

1 mm of water means you have 1 liter per square meter soil.
If you devide the 0.001 m3( 1 liter is 0.001 m3) by 1 m2 you get 0.001 meter
= 1 mm.

The mm/plant you get usually by deviding the amount of irrigated water (liters)
through the irrigated plants ( = liters per plant).

That makes 10 liters per plant are removed be the plants from the water stored
in the soil.
So you have to replace this amount of water. If you have 1 emitter per plant
with a 4 liter/hour capacity your system has to run 2.5 hours.

In general if you have a wetted soil area of about 25% most of the roots might
be in this area so you have to keep this area in a moist range which is likely
to produce maximum yield (100%, 90% or 70% field capacity, I cannot tell).

If you want to finetune your irrigation system you should use some kind of soil
moisture sensor to determine when the soil becomes dryer and the plants may
suffer stress than refill the amount of water to full capacity which depends
only on the kind of soil not on the plants.

Jochen Eberhard

Date: Mon, 12 Feb 96 07:22:16 MST
From: tahowell@ag.gov
Subject: Re: Simple Question

Trickle-L:

If possible, I would like to get a few cents into the discussion on
the "simple question." It's obvious there's no such thing as a
'simple' question nor a 'simple' answer!

My vote goes to Camp C (which assumes both Camps A and B are
incorrect). In Camp C, I would recommend either 1)'slightly'
underirrigating according to either A or B and monitoring plant
response (visually or perhaps more direct responses like LWP with a
pressure bomb or crop temperature with an IRT) and increase irrigation
to alleviate crop water water stress while monitoring soil water
status or 2) (my actual preference) 'slightly' over-irrigating by A
and watching soil water contents (when the soil seems 'too' wet, then
reduce the application rate) while monitoring plant water staus to
make sure of not under-irrigating. This involves measuring soil
factors and plant factors as well as knowing (or more correctly
presuming) what ET may be. Jerry Robb's and Gary Clark's comments and
those from many others are largely correct, but I'm still convienced
until we use all our available "information" we will not succeed!

Hopefully, those doing irrigation research on horticultural crops with
drip will eventually have enough data on plant water consumption (not
ET) to use this volumetric data with scheduling programs based on
volumes/unit area (depths). Lysimeters can partially answer the
question since they measure the volumetric consumption of water (water
volume/plant). Also sap flow gauges can provide a direct measure of
plant volumetric consumption. The correct 'translation' of ET
information from a depth based system (volume/unit area) to a
volumetric system (volume/plant) is clearly not SIMPLE!

Terry Howell

*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 *
* USDA-ARS (806) 356-5750 (Fax) *
* P.O. Drawer 10 tahowell@ag.gov (E-mail) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* *
* 1/2 mi. West I-40 South Access Rd. (shipping) *
*********************************************************************

Date: 12 Feb 96 09:21:49 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Surfacing response to R. Mead and L. Baumhardt

Richard:
The length of the irrigation event probably will have an
effect on surfacing (increasing possibility with increasing time),
but high emitter flow rates will probably further compound this
issue.

I see your point on the differences between surfacing and the
chimney effect. I **would now offer** that the two are related in
cause but that the chimney effect is more pronounced and severe.
I get my **read** on this issue from the three articles listed below
for L. Baumhardt. As always, this is just how it has appeared to me.

Louis:
I'm not positive this will fill your needs, but these are the
articles that ***I interrelate*** to surfacing and the chimney effect.
My first interest in this area was related to perhaps increasing
water distribution perpendicular to dripline direction.

Zimmer, A.L., M.J. McFarland, and J. Moore. 1988.
Upward free water movement from buried trickle emitters.
ASAE Paper 88-2063. Available from ASAE, St. Joseph, MI or the
authors. 16 pp.

Bresler, E. 1978.
Analysis of trickle irrigation with application to design problems.
Irrigation Science 1:3-17.

Ah Koon, P.D., P.J. Gregory and J.P. Bell. 1990
Influence of drip irrigation emission rate on distribution and
drainage of water beneath a sugar cane and a fallow plot.
Agricultural Water Management 17:267-282.

Freddie
*

End of Digest
************************

From root@crcnis1.unl.edu Tue Feb 13 19:57 EST 1996
Date: Tue, 13 Feb 1996 13:44:51 -0600
Message-Id: <199602131944.AA14710@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 419

Contents:
Re: Simpler Question (Trevor Finch <rsne@mpx.com.au>)
A Simpler Question (JRobb209@aol.com)
Re: Simpler Question (M D Greenspan <mdgreenspan@ucdavis.edu>)
Re WUE (meissner.tony@wpo.pi.sa.gov.au)
Eruptions with SDI (geoflow1@slip.net (Rodney Ruskin))

Date: Tue, 13 Feb 96 08:40:16 +1100 (EST)
From: Trevor Finch <rsne@mpx.com.au>
Subject: Re: Simpler Question

It seems to me that the ambiguity is in the ETc rate of "10mm/day". What
does it mean for a single plant?

If it came from a lysimeter with a dripper and a 'wetted area' inside the
weighbridge, doubling the size of the weighed soil should not affect the
actual plant ET rate at all, but the "ET" rate calculated on the gross area
would halve.

Also consider the extreme field case of 10% wetting (a very free-draining
soil). Considering only water consumption, you could now get 10 times as
many vines in the field. The ET rate of each vine should be the same, but
the "ET" rate of the entire field would go up by 10 - you would have to
supply 10 times the water.

As Terry Howel, Jochen Eberhard and Evan Christen have said, to identify
actual, real crop behaviour then objective field measurements of plant and
soil water are required. To identify actual through-drainage, wetting
volumes, maximum water holding capacity, over-watering and water stress
routine field measurments are required.
----
Trevor Finch
Research Services New England
23 Vincent St, Balmain NSW 2041 Australia
tel +61 (2) 810 3563
fax +62 (2) 818 3617

Date: Mon, 12 Feb 1996 18:57:32 -0500
From: JRobb209@aol.com
Subject: A Simpler Question

M.Meron seemed to answer the question in a straight forward manner. 15 hours
will replace the desired 10 mm into the system. The only reason to consider
the soil is to determine if the water replaced in the soil stayed within
reach of the roots. If there was space within the active rootzone when the
irrigation occured then a water balance would say that no deep percolation
occured. With a 25% wetted rootzone the effect of applying 10 mm within the
wetted area is the same as if 40 mm was applied to the wetted area.

If the system is operated in the high frequency manner, which it is designed
for, the soil moisture holding capacity has little bearing on the operation
of the system, since you are not anywhere near any criteria for yield
reductions due to soil moisture stress(MAD). If, on the other hand, it is
operated in a low frequency mode, you must be concerned with the soil
moisture conditions to decide when you must irrigate again to avoid yield
reductions.

Other more interesting questions become relevant: Is the definition for "ET"
relevant for a buried drip system with no evaporation component(Should we
speak of "T")? Does the type of irrigation system have an impact on the "ET"
of a crop? Was the original definition, around 1900, tied to the use of
surface systems and the delivery of water to large projects? Are there
vested interests which would not like a more current definition of "ET"?
Would single row tomato ET be different from two row tomatoe ET on the same
size bed?

Jerry Robb

Date: Mon, 12 Feb 1996 16:16:47 -0800
From: M D Greenspan <mdgreenspan@ucdavis.edu>
Subject: Re: Simpler Question

Short/Simple answer: 15 hours.

(is the correct answer the one with the most votes?)

Longer commentary:
Re: the discussion regarding fraction of ET by the vine crop, my inkling is
that most ET in a drip irrigated vineyard is via the plant. This, of
course, assumes that there is no summer rainfall and that the soil between
the rows is bare and weed/cover crop free. I find it difficult to imagine
that a significant fraction of ET occurs in the row middles. However, I
wonder how much water is lost by evaporation of the wet soil under the
dripper, which is usually sun-exposed (most of the day for E-W row
orientation). No matter how much, I doubt that it comes close to 70% of
total ET. So, my guess is that ET is being overestimated and/or vine
transpiration is being underestimated. I'd be very interested in seeing
the published data on this.

I agree with Terry Howell's suggestion of irrigating somewhat less than the
ET estimate and monitoring plant water stress, although a cumbersome task.
Also, I question the utility of pressure chambers for diagnostic work such
as this (this wasn't always my view). Midday leaf water potential can be
held high by stomatal closure which, to me, is itself a better guage of
water status. In two vineyards, I withheld irrigation for long periods of
time (almost a month) and measured only a slight drop in midday leaf
water potential while stomatal conductance came crashing down.
Unfortunately, measuring stomatal conductance is much more expensive than
measuring leaf water potential. Of course, that is where leaf temperature
may come in handy but I don't want to get into that right now. Sorry for
the digression...

Mark

M.D. Greenspan
Department of Viticulture & Enology
Department of Biological & Agricultural Engineering
U.C. Davis
mdgreenspan@ucdavis.edu

Date: Tue, 13 Feb 1996 11:12:32 +0930
From: meissner.tony@wpo.pi.sa.gov.au
Subject: Re WUE

In regard to the answer given by Bruce Metelerkamp, we do need to be clear about what we mean by water use efficiency. Evan
was talking about water use efficiency in relation to how much water is being applied to grow a plant irrespective of how much
product was being produced. Indications from the work that was done, to which Evan referred, does indicate that a lot less water is
going through the plant ie transpired, than would be indicated via a crop factor Kc. That does not mean we have to dramatically
modify our Kc values because it will depend on the irrigation system used. Hence if we use SDI I think we should be thinking about
a differnt Kc value than if we use a full cover sprinkler system as the losses to evaporation under the two systems will be quite
different.

In regard to the Simpler Question Zach has the right answer. he is right when he says the wetted volume does not matter. Looking
at it from a different perspective the following applies. Firstly 10 mm = 10 l/sq.m. * 60,000 sq. m = 600,000 l. There are 10,000
vines therefore each vine requires 60l. The emitters rate is 4 l/hr hence 60l/4l/hr = 15 hrs.

Cheers
Tony M :-)
*****************************************************
* Tony Meissner *
* Senior Research Scientist (Soils) *
* Primary Industries, South Australia *
* PO Box 411, Loxton SA, Australia 5333 *
* Tel. 085 95 9146 *
* Fax: 085 95 9199 *
* email meissner.tony@pi.sa.gov.au *
*********************************************************

Date: Mon, 12 Feb 96 18:06 PST
From: geoflow1@slip.net (Rodney Ruskin)
Subject: Eruptions with SDI

I have read the discussion on eruption of water to the surface with SDI
with great interest and would like to add some comments. Some are to add
emphasis to opinions already expressed and one is a new point.

Let me first introduce myself to those members of Trickle-l that I have not
met. The company I work for owns the ROOTGUARD (Treflan impregnated
drippers) technology world-wide. We have been involved in many hundreds of
deep SDI systems on permanent crops, in the U.S. and in Australia, Spain,
Israel, India, Mauritius and South Africa. We work through dealers and
licensees and I usually only get involved when something goes wrong. With
that background let me share my experience on eruption of water to the
surface.

1) It is not a common problem with most soils and waters.
2) Short irrigation cycles of less than 1 hour will prevent it from
happening at all.
3) Once it has started it is hard to eradicate.
4) Pulsing and working the surface over the drip line will usually reduce
the problem.
5) Gypsum injection appears to help.
6) I know of only one grower who has not succeeded to bring the problem
into manageable proportion with a combination of 4 and 5, this grower is
also known to Dr. Charles Burt. This grower has a system buried 10" deep
with an inadequate filter system and without a flow meter or pressure
regulator. He does have a time clock.

A frequent cause of eruption which was not raised by other members, is the
problem of pressure compensating drippers flooding when the diaphragm is
held open by foreign matter during operation. This can be foreign matter
ingested under vacuum or root intrusion. Amongst other people this has been
reported by R.B. Hutmacher, R.M. Mead, D.A. Clark, M.S. Peters, R. Swain,
P. J. Shouse, M. van Genuchten, S.S. Vail, C.A. Hawk, T Donovan, J. Jobes,
J. Fargerlund, R. Kershaw, D. Currie in their alfalfa study. The flow can
often increase from 2 lph to as much as 10 lph, with an eruption resulting.
Sometimes the foreign matter is evacuated in the dripper flush cycle, but
due to 3) above, the problem can persist even when the flow returns to
normal. Sometimes the foreign matter is wedged in such a way that it is
never dislodged.

Because we would like to develop P/C drippers with ROOTGUARD for SDI we
have developed our own crude but effective test for this property. The
laboratory test was designed to duplicate field conditions in the most
severe possible circumstances.

Pour 30 mesh sand into the exit hole of emitter by hand. Tap the emitter to
ensure that the sand penetrates.
Apply the sand to 5 drippers at a time.
Apply an air vacuum of 10" Hg to the dripline tube.
Place the drippers under 20 psi of water pressure and measure flow rates.
Switch the water on and off 10 times and again measure flow rates.
Repeat the on/off and measure cycles until improvement in the flow rate stops.

>From the laboratory results we believe that we have reduced the severity of
this problem compared to the P/C driplines presently being sold on the
market for SDI. Field application will soon demonstrate if this is the
case.

Rodney Ruskin.

End of Digest
************************

From root@crcnis1.unl.edu Wed Feb 14 19:57 EST 1996
Date: Wed, 14 Feb 1996 13:45:14 -0600
Message-Id: <199602141945.AA09142@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 420

Contents:
(evan@griffith.dwr.csiro.au (Evan Christen))
(evan@griffith.dwr.csiro.au (Evan Christen))
Efficiency (cburt@oboe.aix.calpoly.edu (Charles M. Burt))
Re: Surfacing response to R. Mead and L. Baumhardt (geoflow1@slip.net (Rodney Ruskin))
Re: Simpler Question (Tivi.Theiveyanathan@cbr.for.csiro.au (Tivi Theiveyanathan))
Re: Reply to Rodney about 2 lph emitters (FLamm@oznet.ksu.edu (Freddie Lamm))
RE: Surfacing response to R. Mead and L. Baumhardt (Manrique Brenes <mjbrenes@ucdavis.edu>)
Re: critters chewing on drip tubes (GrapeGrowr@aol.com)

Date: Tue, 13 Feb 1996 16:38:26 -0600
From: evan@griffith.dwr.csiro.au (Evan Christen)
Subject:

Thanks Bruce for your comments. I agree with your comments, essentially what
is WUE, which is basically the conclusions I have come to, having worked in
a project for 12 months doing salt and water balances in irrigated
vineyards. We can determine how much water is applied and what the losses
are due to subsurface drainage and run off and assume whats left is ET.
This however as you state is not really WUE of the vine to produce grapes.
On the other hand can we manage/measure all the facors that will affect WUE?

Have you considered the hydroponic situation where soil evaporation is not
relevant thus water use must be through transpiration? Would this (like the
sap flow sensors) give us a true water use? At the end of this though our
ability to manage many plants and apply water uniformly and in a timely
manner is limited. Would it be better to irrigate on the basis of minimising
measurable losses thus erring on the side of deficit irrigation and taking
the yields that occur. ie not trying to maximise yield at the risk of
environmental damage. This option is unlikely to be popular and may not be
economic.

Yes please send me your article on WUE.
Do you have any experience of irrigating trees with saline water on sodic soils?
Dr Evan Christen
Irrigation and Drainage Management for Horticulture
CSIRO Division of Water Resources
Griffith Laboratory
Griffith
NSW 2680
Australia
Tel # 61 69 601586
Fax # 61 69 601600

Date: Tue, 13 Feb 1996 16:40:30 -0600
From: evan@griffith.dwr.csiro.au (Evan Christen)
Subject:

Forwarded message to the list

Evan you wrote
>>>>We can determine how much water is applied and what the
losses are due to subsurface drainage and run off and assume
whats left is ET. This however as you state is not really WUE of
the vine to produce grapes. On the other hand can we
manage/measure all the facors that will affect WUE?

It all depends on your goals of providing a WUE number : do you
want it to look good in comparison to other crops, or do you
really want a "translatable" figure that can be compared.
For forestry, we want to know how much of all the water being
used (ie not going into the streams) is producing the wood,
compared to our competitors - sugar cane etc. so that some
"value" per unit water can be calcualted. And so that we can
choose the most WUE or RUE (see my article attached) specie/s.

>>>>Have you considered the hydroponic situation where soil
evaporation is not relevant thus water use must be through
transpiration? Would this (like the sap flow sensors) give us a
true water use? At the end of this though our ability to manage
many plants and apply water uniformly and in a timely
manner is limited. Would it be better to irrigate on the basis of
minimising measurable losses thus erring on the side of deficit
irrigation and taking the yields that occur. ie not trying to
maximise yield at the risk of environmental damage. This option
is unlikely to be popular and may not be economic.

Interesting points..
I suppose it depends on the situation. Here in SA, we are
apparently about to start paying the real cost of water for
irrigation and all other uses according to legislation. (This
suits forestry, as we have always said that irrigation in SA is
very much more wasteful than the rainfed plantation system, - and
we have an unfair "Afforestation Permit System" based on likely
runoff-reductions, whereas no other crop requires such a permit)

>>>Yes please send me your article on WUE.
See attached text file and two WPG (WordPerfect Graphics 2.0)
images.(If you can't see the images, it's not too serious).

>>>>Do you have any experience of irrigating trees with saline
water on sodic soils?
To tell the truth I have no irrigation experience, but may well
have had some by now: (I almost took a job with one of our few
irrigation scheduling consultants a few years ago - pity I
didn't?!?).

BTW - should we not be discussing this openly on the TRICKLE
list? If you want to please put your last message and this reply
on. (I understand that the purpose of your message was originally
to ask for the WUE article, but you then expanded on various
points as I often do as well).

Regards
Bruce
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.
Bruce Metelerkamp SOIL WATER RESEARCH OFFICER
Institute for Commercial Forestry Research,
University of Natal, PO Box 100281
Scottsville, ZA3209
Rep. of South Africa Voice:27 331 62314
E-mail: bruce@icfr.unp.ac.za FAX:27 331 68905
URL http://www.icfrnet.unp.ac.za/~metele
Dr Evan Christen
Irrigation and Drainage Management for Horticulture
CSIRO Division of Water Resources
Griffith Laboratory
Griffith
NSW 2680
Australia
Tel # 61 69 601586
Fax # 61 69 601600

Date: Tue, 13 Feb 1996 17:02:09 -0800
From: cburt@oboe.aix.calpoly.edu (Charles M. Burt)
Subject: Efficiency

The questions of efficiency and uniformity, especially how to define them
and how to quantify them, have been examined and documented by various
groups over the years.

A Task Committee of the Irrigation and Drainage Division of the American
Society of Civil Engineers published a simple but effective article in
1978. Since then our knowledge of the subject has mushroomed, and the need
for better answers has also increased.

This year a 40+ page document was submitted for publication in the
Irrigation and Drainage Journal of ASCE, by the Task Committee on
Describing Efficiency and Uniformity. It represents over 3 years of
serious work by the committee, and provides valuable standardization of
terms and techniques. It is presently in the peer review process, and
should be published soon.

The authors were:

Charles Burt (chair) (Irrigation Training and Research Center, Cal Poly, SLO)
Ken Solomon (Center for Irrigation Technology, Fresno State Univ)
Bert Clemmens (US Water Cons. Lab, Phoenix)
Fedja Strelkoff (US Water Cons. Lab, Phoenix)
John Merriam (prof. emeritus, Cal Poly, SLO)
Ron Bliesner (co-owner, Keller-Bliesner Engr., Utah)
Lee Hardy (now retired, formerly of SCS)
Terry Howell (Ag. Engr., USDA/ARS, Texas)
Dean Eisenhauer (U. of Nebraska)

In addition, a number of us have submitted companion articles to the I&D
Journal.

Keep your eyes open for the special issue of the I&D Journal which will
cover efficiency and uniformity.

Charles Burt
ITRC
Cal Poly
San Luis Obispo, CA 93407

Date: Tue, 13 Feb 96 17:46 PST
From: geoflow1@slip.net (Rodney Ruskin)
Subject: Re: Surfacing response to R. Mead and L. Baumhardt

At 9:27 AM 2/12/96 -0600, Freddie Lamm wrote:
>Richard:
>The length of the irrigation event probably will have an
>effect on surfacing (increasing possibility with increasing time),
>but high emitter flow rates will probably further compound this
>issue.
>

Without doubt. The agricultural industry is almost completely on 2 lph
emitters. While the manufacturers could technically go lower I hesitate due
to plugging risks - which could be serious on long term crops 18+"
subsurface.
Rodney.

Date: Wed, 14 Feb 1996 15:13:53 +1100
From: Tivi.Theiveyanathan@cbr.for.csiro.au (Tivi Theiveyanathan)
Subject: Re: Simpler Question

>Earlier I posed a question about getting from a given irrigition
>requirement in mm to gallons or liters per vine under drip irrigation. Do
>you convert mm to gallons/liters or factor in the wetted area under the
>emitters? I got some answers for a simple conversion, some for a wetted
>area factor and some I couldn't that, well, I couldn't tell. Perhaps I can
>restate the question a little differently with some specifics:
>
>ETc = 10mm and there are 10,000 vines spaced 2 meters by 3 meters in an
>irrigation block, each with a 4 liter per hour emitter. The effective soil
>depth is 1 meter and 25% of the total soil volume gets wetted during an
>irrigation. How long should the irrigation set last to replace the 10mm
>(forget about evaporation and other losses and assume that crop factors are
>correct)?
>
>The surface area is 60,000 square meters
>The irrigation rate is 40,000 liters per hour
>
>One answer is to convert 10mm to liters to irrigation duration: 10mm x
>60,000m2 = 600 m3 = 600,000 liters = 15 hours

Your assumption here is that the water evaporated/transpired at the rate of
10 mm through out the surface of the plantation. This is not correct

>Another answer is to multiply the water use by the 25% being wetted: 10mm
>x 60,000m2 x 0.25 = 150 m3 = 150,000 liters = 3.75 hours

Your assumption here is that only the wetted area lost water to the
atmosphere at the rate of 10 mm. This is also not correct

ET calculation is usually done for homogeneous environments. But, here we
can see two distint status of the soil, wet area and a dry area, both are
important in calculating the volume of irrigation. We need to know the ET
of wet area (i.e 10 mm) and ET of the dry area (for example, 1 mm, use
Ritchie's model to calculate ET of bare soil).

The plantation ET is therefore = (10 x 0.25) + (1 x 0.75) = 3.25 mm.

Now you can use the first method to calculate the total volume required
Volume = 3.25 x 60,000 = 195,000 litres which requires 4.7 hours

Cheers

Tivi

################################################

Tivi Thivianthan
CSIRO Division of Forestry and Forest Products
PO Box 4008
Queen Victoria Terrace
ACT 2600
AUSTRALIA

Phone: + 61 60 281 8231
Fax: + 61 60 281 8239
email: tivi@cbr.for.csiro.au

######################################################

Date: 14 Feb 96 08:37:56 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Reply to Rodney about 2 lph emitters

Rodney:
I understand the issue about plugging with smaller sizes, BUT since
the issue was raised, let me inject a totally different comment about
the hydraulic advantage of lower flowrates.

In areas where stored soil water and precipitation can be used to
buffer the peak water use, a SDI system can be used **effectively**
to only supply a portion of the peak water use. In this case, lower
flowrate products can increase the length of run and still maintain a
high uniformity. Additionally, lower flowrates allow larger zone
sizes when water capacity is fixed. If both of these are
accomplished without increasing plugging, installation and operation
costs will be lower.

I realize this is not news to you, but thought it might elicit some
comments. Not all areas using irrigation are arid and costs are
definitely a concern on lower value field crops.

Thanks for your comment.

Freddie
*

Date: Wed, 14 Feb 1996 11:25:48 -0800
From: Manrique Brenes <mjbrenes@ucdavis.edu>
Subject: RE: Surfacing response to R. Mead and L. Baumhardt

----------

Without doubt. The agricultural industry is almost completely on 2 lph
emitters. While the manufacturers could technically go lower I hesitate =
due
to plugging risks - which could be serious on long term crops 18+"
subsurface.
Rodney.

Most of the drip tapes in the market have at least one model with lower =
flowrates than 2 lph (in fact many go way under 2 lph) and they have =
been used successfully in SDI installations for many years. I think that =
the main reason for not going under 2 lph is a matter of cost. Lowering =
the flowrate in many instances would require more emitters per unit =
length in order to achieve a good wetting pattern.

Manrique Brenes
Bio & Ag. Eng.
UC Davis.

Date: Wed, 14 Feb 1996 14:34:13 -0500
From: GrapeGrowr@aol.com
Subject: Re: critters chewing on drip tubes

Add an extra emmiter at the end rows at the corner of each block and set a
buried 5 gal. plastic bucket below (exposed @6" above ground). This will
give whatever animals water when they want it. It may take a few months for
them to become familar with it.

End of Digest
************************

From root@crcnis1.unl.edu Thu Feb 15 20:03 EST 1996
Date: Thu, 15 Feb 1996 13:52:07 -0600
Message-Id: <199602151952.AA07557@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 421

Contents:
design software (Byron Irvine <pf22408@em.agr.ca>)
Re: Reply to Rodney about 2 lph emitters (geoflow1@slip.net (Rodney Ruskin))
Re: Simpler Question - Tivi's answer ("M. Meron" <MERON@migal.co.il>)
Re: design software ("JOS BALENDONCK, IMAG-DLO, PO-BOX 43, 6700 AA WAGENINGEN, The NETHERLANDS, tel:)
Re: Simpler Question - Tivi's answer ("W. Bryan Smith" <WSMTH@prism.clemson.edu>)
Re: design software (cburt@oboe.aix.calpoly.edu (Charles M. Burt))
Re: design software (Stephen Rawlins <srawlins@ncw.net>)
CNI Action Alert: Republican War on the Environment (cnotes@cnotes.com (CNI))

Date: Wed, 14 Feb 1996 16:43:00 -0500
From: Byron Irvine <pf22408@em.agr.ca>
Subject: design software

I'm new to group as of today!

I am looking for software, either stand alone or spreadsheet macros
which can be used for design of tape and hard wall application for row
crops in annual and perennial crops

suggestions and contacts gratefully received

Byron Irvine phd
Saskatchewan Irrigation Development Centre

Date: Wed, 14 Feb 96 20:04 PST
From: geoflow1@slip.net (Rodney Ruskin)
Subject: Re: Reply to Rodney about 2 lph emitters

At 9:05 AM 2/14/96 -0600, Freddie Lamm wrote:
>Rodney:
>I understand the issue about plugging with smaller sizes, BUT since
>the issue was raised, let me inject a totally different comment about
>the hydraulic advantage of lower flowrates.
>
>In areas where stored soil water and precipitation can be used to
>buffer the peak water use, a SDI system can be used **effectively**
>to only supply a portion of the peak water use. In this case, lower
>flowrate products can increase the length of run and still maintain a
>high uniformity. Additionally, lower flowrates allow larger zone
>sizes when water capacity is fixed. If both of these are
>accomplished without increasing plugging, installation and operation
>costs will be lower.
>
>I realize this is not news to you, but thought it might elicit some
>comments. Not all areas using irrigation are arid and costs are
>definitely a concern on lower value field crops.
>
>Thanks for your comment.
>
>Freddie Lamm
>

Manrique Brenes wrote:
>Most of the drip tapes in the market have at least one model with lower
>flowrates than 2 lph (in fact many go way under 2 lph) and they have been used
>successfully in SDI installations for many years. I think that the main reason
>for not going under 2 lph is a matter of cost. Lowering the flowrate in many
>instances would require more emitters per unit length in order to achieve a
>good wetting pattern.
Manrique Brenes
Bio & Ag. Eng.
UC Davis.

In reply to both Freddie and Manrique:

Both your comments are valid - thank you.
Drip tapes are usually sold for comparatively short term use compared to a
permanent SDI system on trees and vines - so a small risk of plugging with
a tape is tolerable. We aim for 20 years life expectancy.
I stated:
>While the manufacturers could technically go lower "I" (emphasis added)
>>hesitate due to plugging risks - which could be serious on long term crops
>18+"
>subsurface.
I know that some tape manufacturers claim that their products can be used
in deep SDI for permanent crops and will last for 100+ years. I am just a
little more cautious than some of my competitors. Time will tell.

Rodney.

Date: Thu, 15 Feb 1996 12:42:15 GMT+0200
From: "M. Meron" <MERON@migal.co.il>
Subject: Re: Simpler Question - Tivi's answer

I do not agree.

The wetted soil volume has nothing to do with irrigation or transpiration
rates in microirrigation as long as the volume is sufficient to contain
the water lost and applied in a single drydown-irrigation cycle.

Transpiration rates are function of atmospheric demand, crop cover and
crop resistance to water loss (which depends mainly on soil water content
and water stress in general). In the smiple question example 10 mm is
supposed to be the water lost in Evapo-Transpiration, so 10 mm has to be
replaced.

Irrigation replaces lost water, regardless of wetted volumes. Replacing
25% ET because of smaller wetted volume will pretty soon dry out the crop.=========================================================================
MIGAL Galilee Technology Center Crop Ecology Laboratory
Kiryat Shmona PO Box 90 000 Rosh Pina 12 100 ISRAEL
Phone +972-6-953559 Fax: +972-6-944980 Email: MERON@migal.co.il
=========================================================================

Date: Thu, 15 Feb 1996 09:05:25 +0000 (GMT)
From: "JOS BALENDONCK, IMAG-DLO, PO-BOX 43, 6700 AA WAGENINGEN, The NETHERLANDS, tel:
Subject: Re: design software

unsubscribe

Date: Thu, 15 Feb 1996 09:36:39 -0500 (EST)
From: "W. Bryan Smith" <WSMTH@prism.clemson.edu>
Subject: Re: Simpler Question - Tivi's answer

I agree with M. Meron's assessment of irrigation. To base your irrigation
on the wetted/non-wetted area is to ignore the stage of the crop, the leaf
area, the crop water usage, and many other variables. The applied water
should be based on the crop need first.

It seems our questions really are (1) How much water does the individual
plant need per day, which depends on crop stage, humidity and temperature,
and other factors, and (2) how much of the irrigated water is the plant
actually using - this can vary tremendously with the type management
scheme and soil type. For instance, applying all of the water in one
"set" on a coarse, sandy soil would allow a good amount to infiltrate
down past the root volume. The water would have been applied, but the
crop's uptake may not have been fast enough to retrieve it before it
moved down through the soil profile past the effective root area.

Bryan

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of
Clemson University or the Cooperative Extension Service.

Date: Thu, 15 Feb 1996 08:21:26 -0800
From: cburt@oboe.aix.calpoly.edu (Charles M. Burt)
Subject: Re: design software

>I'm new to group as of today!
>
>I am looking for software, either stand alone or spreadsheet macros
>which can be used for design of tape and hard wall application for row
>crops in annual and perennial crops
>
>suggestions and contacts gratefully received
>
>Byron Irvine phd
>Saskatchewan Irrigation Development Centre

There are a number of tools you can purchase.

1. Nelson, out of Walla Walla, Washington, has IRRI-CAD, which
incorporates CAD, hydraulics, and material lists.

2. Netafim has a number of segmented programs for design of valves, hoses,
submains, etc.

3. T-Systems has a hose hydraulics program

4. The Cal Poly ITRC has a hose hydraulics program for the Macintosh or PC.

Charles Burt
Cal Poly ITRC

Date: Thu, 15 Feb 1996 08:50:56 -0800
From: Stephen Rawlins <srawlins@ncw.net>
Subject: Re: design software

Byron

The phone number of Nelson Irrigation is 509-525-7660.

Steve Rawlins

USDA/ARS -- Retired
2638 Eastwood Avenue
Richland, WA 99352
Phone 509-627-4943
FAX 509-627-1841
Email srawlins@ncw.net

Date: Thu, 15 Feb 1996 08:15:59 -0800
From: cnotes@cnotes.com (CNI)
Subject: CNI Action Alert: Republican War on the Environment

The following comes from the monthly "Nation Alert" published by _The
Nation_ magazine:

Just a few of the more than 50 laws and riders attacking the environment
that Republicans have tried to sneak through Congress during 1995 include:

* Representative Mike Oxley (R-OH) has a plan to relax standards to
determine whether toxic sites have been cleaned up. Rather than come out
an admit that he wants to eliminate safety standards, however, Oxley
maintains that his bill will "give more power to the states" and
"streamline" bureaucratic processes. If passed, this bill would likely
have a disproportionate effect on communities of color; statistics show
that minority communities are far more likely to have toxic or polluted
sites located in them. This bill (HR 2500) was actually drafted by Dee
Gavora of the Petroleum Institute. Incidentally (but not coincidentally)
Oxley accepted $92,035 from oil industry political action committees.
Superfund 95, an industry lobbying group, contributed more than $115,310 to
Oxley's campaign. Call Oxley at 202-225-2676 (direct) or 800-962-3524.

* Representative Richard Pombo (R-CA) has introduced a bill to repeal the
Endangered Species Act (HR-2275). Pombo, who receives PAC money from the
Cattleman's Association, also supports a plan to hunt and kill mountain
lions. Pombo received $21,050 in PAC money from corporate agriculture in
the first six months of 1995; this amounted to nearly two-thirds of all his
contributions. Call Pombo at 202-225-1947 (direct) or 800-962-3524.

* Senator Lauch Faircloth (R-VA) has introduced a bill which would repeal
the entire 1990 Clean Air Act. Among other evils, this bill would allow
polluters to refuse to report on their emissions and would prevent citizens
from participating in permit reviews in their own communities. Call
Faircloth at 202-224-3154 or 800-962-3524.

Peace,

Michael Corso
CNI Telecom
--
+ Join CNI Long Distance - the only low cost, FLAT RATE long
+ distance company supporting Peace, Human Rights, the
+ Environment, and the fight against AIDS.
+ Email: longdistance@cnotes.com - we'll send you a
+ reply within 30 seconds.
+ http://www.cnotes.com/telecom/cnitelpage.html
+ New customers receive a FREE Music CD + 100 FREE minutes!

End of Digest
************************

From root@crcnis1.unl.edu Fri Feb 16 20:06 EST 1996
Date: Fri, 16 Feb 1996 13:54:38 -0600
Message-Id: <199602161954.AA02265@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 422

Contents:
Unsubscribe (TFStrong@aol.com)
To all those who want to unsubscribe (meissner.tony@wpo.pi.sa.gov.au)
Unsubscribe Trickle-L (jensengk@eburg.com)
Re: (CNI) posting....PLEASE, Stick to Drip !! (MEAD2513@aol.com)
Re: Simpler Question - Tivi's answer (Tivi.Theiveyanathan@cbr.for.csiro.au (Tivi Theiveyanathan))
Re: (CNI) posting....PLEASE, Stick to Drip !! (Tim1Utah@aol.com)
Re is 10 mm or 4.75 mm (meissner.tony@wpo.pi.sa.gov.au)
Conference Anouncement ("Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>)
Re: Simpler Question - Tivi's answer ("M. Meron" <MERON@migal.co.il>)
(gideon oron <gidi@bgumail.bgu.ac.il>)
Re: design software, source of information (stein@wiz.uni-kassel.de (Thomas-M. Stein))
UNSUBSCRIBE (ELovel9069@aol.com)
RE>simple question Smith and Menson (Jochen.Eberhard@t-online.de (Jochen Eberhard))
RE: RE>simple question (Daniel Schwendler <75471.1717@compuserve.com>)
Re: RE>simple question Smith and Menson (Stephen Rawlins <srawlins@ncw.net>)
UNSUBSCRIBE (<ABUZREIG@net2.eos.uoguelph.ca>)

Date: Thu, 15 Feb 1996 16:30:42 -0500
From: TFStrong@aol.com
Subject: Unsubscribe

UNSUBSCRIBE TRICKLE-L

Date: Fri, 16 Feb 1996 09:42:16 +0930
From: meissner.tony@wpo.pi.sa.gov.au
Subject: To all those who want to unsubscribe

I hope this little explanation will help those people wishing to unsubscribe now or at a later date.

Conceptually, there is a computer which handles many discussion lists at a particular site. This computer is called LISTERV eg the
computer that handles the trickle group is LISTSERV@unl.edu. When you first subscribed to get onto trickle-l or irrigation-l you
subscribed to the appropriate LISTSERV. The LISTSERV keeps a list of people who have subsribed to a particular list. Hence to
unsubscribe you send your unsubscribe to the appropriate LISTSERVer.

If you want to send a message, like this one, you send it to the discussion list. This computer then "knows" which list you want your
message to be distributed to and distributes the message to all the other subscribers. .

Alternatively, it may help if you think of it a receiving magazines from a publisher. The publisher (LISTSERV) has many magazines
catering to different interests. So, you send your subscription to the publisher for a particular magazine. The publisher has a
subscription list for each of its magazines.. It then sends out the magazines to the subscribers on the list. hence, if you want to
unsubscribe, you send your "unsubscription" to the publisher to take you off the list for that magazine. I hope this makes it clear

Cheers
Tony M :-)
*****************************************************
* Tony Meissner *
* Senior Research Scientist (Soils) *
* Primary Industries, South Australia *
* PO Box 411, Loxton SA, Australia 5333 *
* Tel. 085 95 9146 *
* Fax: 085 95 9199 *
* email meissner.tony@pi.sa.gov.au *
*********************************************************

Date: Thu, 15 Feb 1996 17:39:12 +0100
From: jensengk@eburg.com
Subject: Unsubscribe Trickle-L

Unsubscribe Trickle-L

Greg K. Jensen
Mountain Valley Turf & Irrigation
509-925-7353

Date: Thu, 15 Feb 1996 21:02:10 -0500
From: MEAD2513@aol.com
Subject: Re: (CNI) posting....PLEASE, Stick to Drip !!

PLEASE, Stick to Drip !!

It is my intention to maintain the integrity of Trickle-L by encouraging the
variety of individuals on the list to discuss the topic of drip (or
microspray) irrigation. While I am completely behind freedom of speech and
abhor censorship, I won't stand for disruptive comments. We're here to
discuss a certain technology that truly is saving resources, and feeding
people. Politics, no matter what direction it may come from, is irrelevant to
this forum.

Last time we had a minor flame war, "we" lost 10 individuals which by
themselves unsubscribed. They were most likely discouraged by the spiraling
downward quality of our discussion group. I don't want that to ever happen
again.

Please don't make me be the bad guy and unsubscribe you with a few
keystrokes. Let's continue to have great discussions about DRIP IRRIGATION !

Richard Mead
Trickle-L owner/manager

Date: Fri, 16 Feb 1996 13:00:56 +1100
From: Tivi.Theiveyanathan@cbr.for.csiro.au (Tivi Theiveyanathan)
Subject: Re: Simpler Question - Tivi's answer

>I do not agree.
>
>The wetted soil volume has nothing to do with irrigation or transpiration
>rates in microirrigation as long as the volume is sufficient to contain
>the water lost and applied in a single drydown-irrigation cycle.

I agree with your comment. I was only refering to the estimation of ET.
My concern is how did we come up with 10 mm as the crop water requirement.
Penman-Moneith method can't estimate for a heterogenous condition where
part of the soil wet and other part is dry. Also soil moisture
measurements may not give the actual deficit in terms of depth. The only
way to estimate the crop water requirement is to use Penman-Monteith for
two conditions and get a weighted mean.

>
>Transpiration rates are function of atmospheric demand, crop cover and
>crop resistance to water loss (which depends mainly on soil water content
>and water stress in general). In the smiple question example 10 mm is
>supposed to be the water lost in Evapo-Transpiration, so 10 mm has to be
>replaced.

If 10 mm is supposed to be the water lost, then 10 mm must be replaced.
But is it 10 mm or 4.75 mm?. That is the question

Cheers

Tivi

################################################

Tivi Thivianthan
CSIRO Division of Forestry and Forest Products
PO Box 4008
Queen Victoria Terrace
ACT 2600
AUSTRALIA

Phone: + 61 60 281 8231
Fax: + 61 60 281 8239
email: tivi@cbr.for.csiro.au

######################################################

Date: Thu, 15 Feb 1996 21:10:16 -0500
From: Tim1Utah@aol.com
Subject: Re: (CNI) posting....PLEASE, Stick to Drip !!

Good call Richard!!!!!!!! I am behind you Tim Wilson

Date: Fri, 16 Feb 1996 13:30:09 +0930
From: meissner.tony@wpo.pi.sa.gov.au
Subject: Re is 10 mm or 4.75 mm

I think some of us are getting confused between depth and volume. Whwn we talk about an ETc of 10 mm we are taling about a
depth of 10 mm evapoartion spread out over a field populated by x no of plants. But to find out what that means in volume of water
to the plant we need to convert the depth (mm) to litres by multiplying the depth by the conversion rate (depth/unit area) by the area.
This gives a volume for the area and then we must divide by the number of plants.

The conversion factor for a depth of 1 mm over 1 ha (10,000 sqm) is 10,000l or 10 kl. Hence, 10 mm = 100 kl/ha. If we have a
plant density of 1000 plants per ha, each plant needs 100/1000 kl = 0.1 kl or 100 litres. Hence we need to supply to that plant 100
litres, hence it does not matter whether we supply this over 10 sqm ( 10 mm over 10 sqm) or 1 sq m (100 mm over the area) or 0.1
sqm (1000 mm over the area). It is another question as to whether the soil could hold that amount or whther the root system
explores all the area or part of it.

I hope this helps.

Cheers
Tony M :-)
*****************************************************
* Tony Meissner *
* Senior Research Scientist (Soils) *
* Primary Industries, South Australia *
* PO Box 411, Loxton SA, Australia 5333 *
* Tel. 085 95 9146 *
* Fax: 085 95 9199 *
* email meissner.tony@pi.sa.gov.au *
*********************************************************

Date: Wed, 14 Feb 1996 14:44:42 +200
From: "Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>
Subject: Conference Anouncement

(taken from the TAMU TWRI WWW page)
INTEGRATED MANAGEMENT
OF SURFACE AND GROUND
WATER

sponsored by The Universities Council on Water Resources
_________________________________________________________________

What?
* Technical sessions, discussions, committee meetings
* Edwards Aquifer symposium
* Professional tour of Edwards Aquifer region
* Workshop on Risk Analysis
* Social activities, reception, luncheons, banquet
* Awards and honors
* Spouse's program
_________________________________________________________________

Where?
* St. Anthony Hotel, San Antonio, Texas
* Two blocks from the famed River walk with restaurants and
shops
* Great hotel rates! Plan to bring the family and extend
your stay
to sample cultural and recreational activities throughout
the area

_________________________________________________________________

When?
* July 30 - August 2, 1996
* Professional tour of the Edwards Aquifer region on July 30
* Workshop on Risk Analysis on July 30
_________________________________________________________________

Extras!
* Sea World of Texas (discounts available)
* Fiesta Texas theme park (discounts available)
* River Walk and River Center Mall
* Hemis Fair park
* The Alamo
* Market Square (Mexican market)
* San Antonio Zoo and Botanical Garden
* Much, much more!
_________________________________________________________________

Registration Fees.
* $225 for first delegate from UCOWR members, $125 per
additional
delegate
* $55 per day for individual members and non-UCOWR attendees
* Tour and workshop offered at cost

Announcement and
Call for Papers

Integrated resource management is the new paradigm of the 90's
for
water resource planners and managers. Watersheds have been
rediscovered as the basic units for water resource planning,
but
concerned citizens now demand that planning and management be
conducted in concert with concepts of sustainable use and
protection
of other physical and biological resources in the watershed.
Institutions for resource protection, established to implement
federal
regulatory programs, are ill-suited to manage multimedia and
multiple
resource programs focused on watershed rather than state
boundaries.
The goal of the conference is to explore concepts and
experiences that
promote efficient use and protection of the total water
resources
within watersheds.

Integrated management of surface and ground waters is a
complex issue
whose solutions demand the skills of professionals from a wide
range
of disciplines. Typical supply-oriented approaches are rapidly
being
replaced by multi-objective planning that includes demand
management,
quality protection, habitat maintenance, aesthetics and
recreation.
Papers that address the following topic areas will be welcome:
* Legal and institutional impediments to integrated use and
management
* Incorporation of groundwater into watershed management
plans
* Risk assessment for surface and ground water systems
* Water marketing
* Preservation of biological diversity
* Artificial recharge
* Water quality impacts of integrated use
* Conflict resolution in an integrated use setting

Where possible papers should also address the roles of
universities
and their faculties in resolution of these issues.

Dr. Wayne R. Jordan
General Program Chair-UCOWR '96
Texas Water Resources Institute
Texas A&M University
College Station, TX 77843-2118
Phone: (409) 845-1851 Fax: (409) 845-8554
Email: twri@twri.tamu.edu

UCOWR-'96
July 30-August 2,
1996

Conference theme:

Integrated
Management of
Surface and Ground
Water

Anyone interested in contributing a paper should submit an
abstract by
February 1, 1996 to Dr. Lloyd Urban, Technical Program Chair,
Water
Resources Center, Texas Tech University Box 41022, Lubbock, TX
79409-1022, (806)742-3597, FAX: (806)742-3449, email:
lurban@coe2.coe.ttu.edu. Abstracts should include a title,
author's
name(s) and affiliation(2), complete address (es) (zip+4),
phone, fax
and email numbers. Full papers for the printed proceedings
will be due
May 20, 1996. Instructions for paper preparation will be sent
to all
those submitting abstracts. Proceedings will be distributed to
all
attendees at the meeting. A technical tour of the Edwards
Aquifer
region is planned for July 30, 1996, the day prior to the
opening
session of UCOWR '96. The full-day tour will include stops to
illustrate the geology of the region, observe water resource
development and use, and see examples of water-based
recreation and
major springs and their biological ecosystems. Water resource
professionals will accompany the tour to interpret significant
physical and biological features of this unique water resource
system.
This tour will serve as an excellent introduction to the UCOWR
'96
symposium on the Edwards aquifer.

Date: Fri, 16 Feb 1996 09:49:17 GMT+0200
From: "M. Meron" <MERON@migal.co.il>
Subject: Re: Simpler Question - Tivi's answer

Glade to agree with you on "10 mm gone - 10 mm to be replaced regardless
of wetted volume".

As for ET estimation in sparse canopies:

A simplicistic but quite effective method is to multiply the radiative
term of the Penman equation (forget Monteith) with the crop light
interception measured in the field. This works very good with most
well irrigated field crops of partial cover in drip irrigation.

In horticultural crops that is less straight forward because of row height
and interrow turbulence, and because of diverse behaviour of stomatal
conductances of different species, fruit loads and other crop specific
factors.

Many contributors have aready addressed irrigation scheduling in
hoticultural crops and the issue was enlighted from many aspects. The
simple answer to the simple question asked remains the opening sentence.
=========================================================================
MIGAL Galilee Technology Center Crop Ecology Laboratory
Kiryat Shmona PO Box 90 000 Rosh Pina 12 100 ISRAEL
Phone +972-6-953559 Fax: +972-6-944980 Email: MERON@migal.co.il
=========================================================================

Date: Fri, 16 Feb 1996 10:53:56 +0200 (IST)
From: gideon oron <gidi@bgumail.bgu.ac.il>
Subject:

Dear Friend
Ask please Dave to open his mail. He has a message from Gideon
Thanks
Gideon

Date: Fri, 16 Feb 1996 11:38:16 +0100 (MEZ)
From: stein@wiz.uni-kassel.de (Thomas-M. Stein)
Subject: Re: design software, source of information

Regarding information on irrigation software

Byron Irvine wrote:

>I'm new to group as of today!
>
>I am looking for software, either stand alone or spreadsheet macros
>which can be used for design of tape and hard wall application for row
>crops in annual and perennial crops
>
>suggestions and contacts gratefully received
>
>Byron Irvine phd
>Saskatchewan Irrigation Development Centre

Charles Burt answered:
----------------------
>There are a number of tools you can purchase.

and he listed a number of companies / organisations providing
information.

I would like to add some Information on IRRISOFT:

We have established a World Wide Web Database on irrigation
and hydrology software called IRRISOFT. It may freely be
accessed through the URL:

http://www.wiz.uni-kassel.de/kww/irrisoft_i.html

IRRISOFT holds information on software packages as well as
LINKS to servers holding additional information or download
facilities. Addresses and emails to the contact persons are
included as well.(Information on IRRI-CAD is also listed).

If somebody on this list would like his program listed and
described may please contact me.

Best regards

Thomas
______________________________________________________________________________

Thomas-M. Stein
University of Kassel (FB11) Phone : (+49)-5542-98-1632
Dep. of Rural Engineering and Fax : (+49)-5542-98-1588
Natural Resource Protection Email : stein@wiz.uni-kassel.de
Nordbahnhofstr. 1a WWW : http://www.wiz.uni-kassel.de/kww/
D-37213 Witzenhausen, GERMANY List owner: IRRIGATION-L@listserv.gmd.de
______________________________________________________________________________

IRRISOFT Database on Irrigation & Hydrology Software
http://www.wiz.uni-kassel.de/kww/irrisoft/irrisoft_i.html
______________________________________________________________________________

Date: Fri, 16 Feb 1996 08:16:18 -0500
From: ELovel9069@aol.com
Subject: UNSUBSCRIBE

UNSUBSCRIBE

Date: Fri, 16 Feb 96 10:39 +0100
From: Jochen.Eberhard@t-online.de (Jochen Eberhard)
Subject: RE>simple question Smith and Menson

The discussion is getting closer to the problem.
I think the problem is the *label* mm which is based on the soil not the plant.
Once again, the *label* 10 mm means that each squaremeter of soil needs 10 liter
of water to be saturated or be filled up to the original level before the
deplation has started. It has nothing to do with the crop.
In the specific case the crop and the irrigation system are the major problems
when working with ET-methods. The most crop roots are usually located around the
drip (dripper ?) so most of the water will be taken up by the plant in this
wetted zone. So the plant will suffer stress, when the water deficit in this
rooting area is to high, also the calculated ET rate is low. Using the *simple
question* exampel, 10 mm is not very much (the water use for one or two days),
but when the crop roots can take up this amount of water only in 25% of the
soil, because most of them are in this area. So the theoretical water deplation
in this 25% would be 40 liters, which is quite a lot.
As far as I know, the ET calculation is based on the water use of a completely
soil covering crop (grass) or the evaporation of an open water surface converted
with some coefficients for a specific crop. So the wateruseage of liters per
squaremeter is correct. The convertion to the specific crop depends on leaf area
index, stomata behavior of the plants, specific water uptake of the roots and a
few other things. So the calculated ET often is incorrect.
While working with row crops and drip irrigation the water demand of the crop
should be calculated in liters per plant, then it is no big deal to calculate
the watering time.

Jochen Eberhard, Germany
Jochen.Eberhard@t-online.de

Date: 16 Feb 96 10:44:25 EST
From: Daniel Schwendler <75471.1717@compuserve.com>
Subject: RE: RE>simple question

Dear Sirs:

Please allow me to introduce myself along with my company. My name is Dan
Schwendler and the company I work for is AquaSaver International Corporation.

I have been reading many of the conversations sent back and forth, particularily
those regarding EvapoTranspiration. Many references have been made these common
weather stations designed to give the reference value which is then multiplied
by the estimated coefficient to give an idea of what a plant is going through.

We manufacture a product that bypasses all these estimates. You may be familiar
with some of our prototype versions, which were invented by Dr. Alain Perrier
and Dr. Christian de Pescara. The most well known were the stations B.E.A.R.N.,
and S.A.M.E.R. (Systeme Automatique de la Mesure d'evapotranspiration Reelle).

We have industrialized these systems and are now offering them to growers and
other irrigants who wish to monitor plant stress, Real or Actual
EvapoTranspiration (ETr), and other things. For apparent reasons I cannot go in
depth on the product here, however, should you require additional technical
information, please contact me at 75471.1717@compuserve.com.

Dan Schwendler

Date: Fri, 16 Feb 1996 09:32:23 -0800
From: Stephen Rawlins <srawlins@ncw.net>
Subject: Re: RE>simple question Smith and Menson

Jochen:

When estimating ET for a crop from something like Penman, we always have to
include a crop coeficient. For a row crop, the crop coefficient is small
when the plants begin to emerge, and increases to a maximum when the canopy
closes. In your case, can't the fact that the canopy is not closed be
handled by selecting the appropriate crop coefficient?

Steve Rawlins
USDA/ARS -- Retired
2638 Eastwood Avenue
Richland, WA 99352
Phone 509-627-4943
FAX 509-627-1841
Email srawlins@ncw.net

Date: Fri, 16 Feb 1996 13:09:06 EDT
From: <ABUZREIG@net2.eos.uoguelph.ca>
Subject: UNSUBSCRIBE

UNSUBSCRIBE

End of Digest
************************

From root@crcnis1.unl.edu Sat Feb 17 20:05 EST 1996
Date: Sat, 17 Feb 1996 13:54:41 -0600
Message-Id: <199602171954.AA15315@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 423

Contents:
Re: To all those who want to unsubscribe (Vince Bralts <bralts@ecn.purdue.edu>)

Date: Sat, 17 Feb 1996 11:57:29 -0500
From: Vince Bralts <bralts@ecn.purdue.edu>
Subject: Re: To all those who want to unsubscribe

Unsubscribe

End of Digest
************************

From root@crcnis1.unl.edu Sun Feb 18 20:07 EST 1996
Date: Sun, 18 Feb 1996 13:55:37 -0600
Message-Id: <199602181955.AA23372@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 424

Contents:
Unsubscribe Trickle-L (gkelly@cycor.ca (Glen Kelly))
Leslie Roy (GroAire@aol.com)

Date: Sun, 18 Feb 1996 12:30:55 -0400
From: gkelly@cycor.ca (Glen Kelly)
Subject: Unsubscribe Trickle-L

Unsubscribe Trickle-L

Glen Kelly

Date: Sun, 18 Feb 1996 14:28:33 -0500
From: GroAire@aol.com
Subject: Leslie Roy

I received a message on the 17th from
V1_server.efcom!Leslie_Roy@news1.wolfe.net
However; the listserver returned my reply to the sender as undeliverable. The
individual is involved in the Hops industry for 10 years. Anyone knowing of
the correct address, please contact me.

Dave Enyeart
GroAire@aol.com

End of Digest
************************

From root@crcnis1.unl.edu Mon Feb 19 20:08 EST 1996
Date: Mon, 19 Feb 1996 13:55:48 -0600
Message-Id: <199602191955.AA08363@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 425

Contents:
Re: Unsubscribe Trickle-L (GlynMiami@aol.com)
(Peter Crimmin <peter@vis.com>)

Date: Sun, 18 Feb 1996 21:03:01 -0500
From: GlynMiami@aol.com
Subject: Re: Unsubscribe Trickle-L

Unsubscribe Trickle-L

Date: Mon, 19 Feb 96 08:13:33 -0500
From: Peter Crimmin <peter@vis.com>
Subject:

set trickle-l mail digest

End of Digest
************************

From root@crcnis1.unl.edu Tue Feb 20 20:13 EST 1996
Date: Tue, 20 Feb 1996 13:56:20 -0600
Message-Id: <199602201956.AA28555@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 426

Contents:
Simple Question--An Answer Which May Be Too Simple (Irrometer@aol.com)
Two email discussion groups: SoWaCS & RR ("Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>)
Drip & Wastewater Numbers (Manrique Brenes <mjbrenes@ucdavis.edu>)

Date: Mon, 19 Feb 1996 18:40:50 -0500
From: Irrometer@aol.com
Subject: Simple Question--An Answer Which May Be Too Simple

While I have been gone the past week at the Tulare Farm Show, I did get to
read
the discussion concerning a simple question [27 minutes worth]. The
validity of
"field measurements" mentioned by Finch, Howell and Christen--even "soil
moisture measurements"-- is practically as valid today [perhaps more so?] as
it
was in the prior seven or so odd decades since tensiometers and other
valid devices appeared in the technology of managing soil water status by in
fact
actually measuring that which we wish to control, limit as a variable, or
otherwise
manipulate to achieve the practical desired objective of "irrigation".
Although
now out of print a very good reference is AGRONOMY No. 11, Irrigation of
Agricultural
Lands, page 582 Fig. 30-3. When and How Much to irrigate, would be an
adequate
subtitle. At least worth a mention, which I humbly submit.

Regards, Bill Pogue, irrometer@aol.com

Date: Tue, 20 Feb 1996 8:32:36 +200
From: "Bruce Metelerkamp" <BRUCE@mailgate.icfrnet.unp.ac.za>
Subject: Two email discussion groups: SoWaCS & RR

Tricklers.

I am iniating two discussion groups on the topics:
Automated electronic SOIL WATER CONTENT SENSORS and
LENGTH MONITORING SENSORS (for tree stem diameters for example).
These are summarised below.

Please reply to me ONLY at bruce@icfr.unp.ac.za NOT THIS LIST.

If there is enough support from the list, the discussion can be
run via TRICKLE-L, but due to the specific nature of the two
groups, and the expected amount of material, will probably not
be.

So please email me and tell me which of the two lists (or both)
you would like to subscribe to. The first message is due out
shortly.

(Please forgive this canvassing message if you are not
interested.)

Details are also available at my Web site: (see URLs below).

Summarys will, from time to time, be posted to the TRICKLE-L,
IRRIGATION-L and FOREST lists.

Bruce Metelerkamp

CS615 SOIL WATER CONTENT SENSORS (SoWaCS group)
There has been a growing need for an accurate but
inexpensive automated soil water content sensor that is durable
and works over the complete wet to dry range.

I have tried various sensors for use with continuous datalogged
systems, but these did not have the required range and/or
ruggedness.
Gypsum blocks are the worst, followed closely by nylon blocks,
Watermark sensors and heat dissipation sensors. I have not
yet tried paired needle heat pulse methods, nor the
"capacitance" methods. (I do not know what the latter
entails).

The promise of Time Domain Reflectometry (TDR) was limited by the
electronics required to use it, but a new TDR-like probe,
the CS615 sensor, seems to have overcome these problems.
It can be hooked up directly to a datalogger (all the Campbell
Scientific Incorporated models, anyway).

I am currently corresponding with a number of users and
other potential users to assess the sensor, which at less
than US$250, seems to be set to take the world.
Please contact me if you would like to join the email
discussion group on this and related sensors.

===========================================================

AUTOMATED TREE STEM (DBH) MEASUREMENTS (and other
length-changing applications). (RR group)
Automated measurements of tree stem diameters have evolved
through from dial gauge dendrometers, LVDT systems, to
capacitance-based sensors, the latest of which is called the
Rubbery Ruler (RR).
This relatively robust, cheap and small sensor operates on a
low voltage and returns a frequency proportional to its
"stretch". It is independant of temperature, and can be
logged with a good quality logger.

I am looking into getting dedicated microprocessors to
function as independant loggers thus reducing the logger
and extension wire requirements.

I have already run a sucessful discussion group on
manually-read band dendrometers, and now want to expand
this to the automated systems available: (see the
correspondance on my band_dendrometer homepage at
URL http://www.icfrnet.unp,ac.za/~metele/band_dendrometry ).

If you would like to join one or both of these discussion
groups please contact me.

Heres to good measuring - and quality data!
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.
Bruce Metelerkamp SOIL WATER RESEARCH OFFICER
Institute for Commercial Forestry Research,
University of Natal, PO Box 100281
Scottsville, ZA3209
Rep. of South Africa Voice:27 331 62314
E-mail: bruce@icfr.unp.ac.za FAX:27 331 68905
URL http://www.icfrnet.unp.ac.za/~metele
/SoWaCS.html
/RR.html

Date: Tue, 20 Feb 1996 10:44:23 -0800
From: Manrique Brenes <mjbrenes@ucdavis.edu>
Subject: Drip & Wastewater Numbers

I am working a research project involving drip irrigation tape for the =
application (disposal) of secondary effluent.
I have been looking for recent numbers of the total area using drip =
systems and the total area currently irrigated with wastewater effluent. =
I know of a few projects using drip systems to apply wastewater but I =
would like to have a feel of how many are in use or planned and whether =
or not any of them is using tape.
If anyone has a feeling for any of these numbers or know where to find =
them please send me a few lines.

Area currently using drip tape? Per country (US, Australia, Spain, =
etch.) or worldwide.
Area currently using wastewater effluent in irrigation? Per country =
(US, Australia, Spain, etch.) or worldwide.
Any projects using drip systems for the disposal or application of =
wastewater and some numbers on them (years of use, area, etch.

Thanks.

Manrique Brenes
Bio. & Ag. Eng.
UC Davis.

End of Digest
************************

From root@crcnis1.unl.edu Wed Feb 21 20:08 EST 1996
Date: Wed, 21 Feb 1996 13:56:50 -0600
Message-Id: <199602211956.AA22263@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 427

Contents:
Unsubscribe (Stephen Stortz <sstortz@gramercy.ios.com>)
RE Unsubscribe (meissner.tony@wpo.pi.sa.gov.au)
TRICKLE-L digest 426 -Reply (thomson.tony@wpo.pi.sa.gov.au)
Re: Drip & Wastewater Numbers (GroAire@aol.com)
(Ing.Agr. Claudio Garcia <cgarcia@inialb.org.uy>)

Date: Tue, 20 Feb 1996 17:09:47 -0500 (EST)
From: Stephen Stortz <sstortz@gramercy.ios.com>
Subject: Unsubscribe

Unsubscribe trickle-l

Date: Wed, 21 Feb 1996 09:39:54 +0930
From: meissner.tony@wpo.pi.sa.gov.au
Subject: RE Unsubscribe

It seems my effort to help people get it right to unsunscribe has fallen on 'blind eyes'. Such is life

Cheers
Tony M :-)
*****************************************************
* Tony Meissner *
* Senior Research Scientist (Soils) *
* Primary Industries, South Australia *
* PO Box 411, Loxton SA, Australia 5333 *
* Tel. 085 95 9146 *
* Fax: 085 95 9199 *
* email meissner.tony@pi.sa.gov.au *
*********************************************************

Date: Wed, 21 Feb 1996 12:10:00 +0930
From: thomson.tony@wpo.pi.sa.gov.au
Subject: TRICKLE-L digest 426 -Reply

both lists please

Date: Tue, 20 Feb 1996 21:25:16 -0500
From: GroAire@aol.com
Subject: Re: Drip & Wastewater Numbers

Hello Paula & Manrique

I received the file fine that you emailed. Thank you !
You requested info on total acreage of effluent and drip. The project I'm
currently working on is a total of 7500 acres here in Colorado. It will be
native grass when completed and the system will be used two years then
abandoned.

Dave Enyeart
GroAire@aol.com

Date: Wed, 21 Feb 96 10:49:01 URU
From: Ing.Agr. Claudio Garcia <cgarcia@inialb.org.uy>
Subject:

Manrique: Here in INIA (National Research Institute of
Agriculture), Dr. Alejandro La Manna is currently working with
drip irrigation. He use wastewater to irrigate pasture and
some vegetables. You can contact with him at
alamanna@iniale.org.uy, if you can not contact with him let me
know.
---

Soil Water and Climate Department
NATIONAL RESEARCH INSTITUTE OF AGRICULTURE Ing.Agr. Claudio Garcia
ANDES 1365 P12 MONTEVIDEO URUGUAY cgarcia@inialb.org.uy
CP 11100 SOUTH AMERICA

End of Digest
************************

From root@crcnis1.unl.edu Sat Feb 24 05:28 EST 1996
Date: Fri, 23 Feb 1996 23:17:32 -0600
Message-Id: <199602240517.AA17193@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 428

Contents:
l (AsiaLink@aol.com)

Date: Sat, 24 Feb 1996 00:18:07 -0500
From: AsiaLink@aol.com
Subject: l

unsubscribe - l

End of Digest
************************

From root@crcnis1.unl.edu Mon Feb 26 03:11 EST 1996
Date: Sun, 25 Feb 1996 20:59:35 -0600
Message-Id: <199602260259.AA03638@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 429

Contents:
Re: Drip & Wastewater Numbers (Dripigate@aol.com)

Date: Sun, 25 Feb 1996 21:59:13 -0500
From: Dripigate@aol.com
Subject: Re: Drip & Wastewater Numbers

Roger Penny of Netafim Florida 1 800 393 1414 has spent the last five years
working on this subject.

Robin Franks Netafim irrigation.

End of Digest
************************

From root@crcnis1.unl.edu Tue Feb 27 04:36 EST 1996
Date: Mon, 26 Feb 1996 21:00:33 -0600
Message-Id: <199602270300.AA26784@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 430

Contents:
Installation of SDI (Richard Mead <rmead@asrr.arsusda.gov>)
Re: Installation of SDI ("W. Bryan Smith" <WSMTH@prism.clemson.edu>)
Re: Installation of SDI (FLamm@oznet.ksu.edu (Freddie Lamm))
Rodent survey in ****SDI only*** (FLamm@oznet.ksu.edu (Freddie Lamm))
SDI Technology session following WFOK (FLamm@oznet.ksu.edu (Freddie Lamm))
(Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>)
(Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>)
(Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>)
RE: Installation of SDI (Goldberg <goldberg@eden.com>)

Date: Mon, 26 Feb 1996 11:33:40 -0500
From: Richard Mead <rmead@asrr.arsusda.gov>
Subject: Installation of SDI

There is very little literature on the techniques and practices of
installing subsurface drip tape or hose. From the reading I've done in
agricultural magazines, there seems to be just a few companies out there
that specialize in subsurface drip installation. Everyone else seem to build the
installation 'shanks' in their farm shops.

Andros Engineering in Santa Margarita, California, is one company (that I'm
aware of) that has surged ahead in installed SDI systems for vegetable
farms. They make several types of installation shanks:

A universal shank for depths to 35 cm (14 in).
A shallow shank for depths to 15 cm (6 in).
A special shank for laying polyethylene hard hose in orchards and vineyards
at various depths.

Drill Drip out of Australia uses a SDI installer for turf with only an 18
HP tractor. It augments a rotating disk that cuts the turf or sod followed
by a tape injecting system from 5 to 30 cm (2-12 in) and then a surface
roller that compacts the soil after installation.

There are also SDI systems out there that use a "Vibratory Plow" to break
the soil structure in order to use less energy.

My questions to the Trickle-L gang are:

a) How much energy would a "Vibratory Plow or Shank" save (on average) vs.
a traditional SDI shank?

b) At what depth in the soil does it become necessary to switch from
installing tape to installing hard hose? Is there a general rule that says
at "X" soil at "Y" depth, install the harder drip line due to the hydraulic
nonuniformity caused by the tape being "crushed" or "squeezed"?

Richard M. Mead
Trickle-L owner/manager

p.s.

For those who are new to Trickle-L or you just love reruns, the
November '95, December '95 and January '96 archives of Trickle-L are now
available.

To obtain any of these, type the command: GET TRICKLE-L LOG9XXX,
where "LOG9512" would be December '95 etc.
Send the typed command as an email message to LISTSERV@UNL.EDU
Please do NOT send the command to TRICKLE-L@UNL.EDU

Date: Mon, 26 Feb 1996 11:48:40 -0500 (EST)
From: "W. Bryan Smith" <WSMTH@prism.clemson.edu>
Subject: Re: Installation of SDI

Richard,
Another question in line with your own. As I understand the vibratory
plow concept, the pipe or tubing is first assembled, then attached to the
plow and pulled along into the void made by the plow. Dragging this
emitterline or drip tape underground might cause a few problems:

(1) Stretching or even pulling apart the drip line during installation

(2) Clogging emitters or outlets due to the abrasion of the dripline
with the side if the created void

Of course, I guess this could be avoided if the vibratory plow shank and
"bullet" were large enough. I would really be interested to hear of any
installations with the vibratory plow method, what type of soils were
involved, and how well the installation turned out. I'm certainly not
against using this method, just curious how it works.

Bryan

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of
Clemson University or the Cooperative Extension Service.

Date: 26 Feb 96 11:35:31 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Re: Installation of SDI

I

RICHARD MEAD WROTE:

b) At what depth in the soil does it become necessary to switch from
>installing tape to installing hard hose? Is there a general rule that
>says at "X" soil at "Y" depth, install the harder drip line due to the
>hydraulic nonuniformity caused by the tape being "crushed" or
>"squeezed"?

I KNOW OF NO GENERAL RULE, BUT I THINK IN GENERAL (AND
MAYBE YOU ARE IMPLYING THAT ASSUMPTION) THAT AS Y
GETS GREATER, THE NATURAL BRIDGING OF THE SOIL
ALLOWS FOR USE OF TAPE. THIS WOULDN'T BE TRUE IN
NON-BRIDGING SOILS, SUCH AS COARSE SANDS. AT SHALLOW
DEPTHS, DISREGARDING COMPACTION, THE WEIGHT OF THE
SOIL ABOVE THE DRIPLINE COULD BE COMPARED TO THE LOAD
THAT THE DRIPLINE SUPPORTS THROUGH ITS OWN PRESSURE
AS A FIRST GUESTIMATE.

FREDDIE
*

Date: 26 Feb 96 11:43:35 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: Rodent survey in ****SDI only***

TO ALL THOSE OUT THERE IN TRICKLE-L LAND

SUBJECT: RODENT CONTROL FOR ****SDI ONLY****

I HAVE SUMMARIZED THE REMARKS THAT I HAVE IN MY TRICKLE-L
FILES ON RODENTS SINCE FEBRUARY 1995. I WOULD APPRECIATE
ANY UPDATES OR ADDITIONAL EXPERIENCES. AS I SAID IN MY
POSTING TO TRICKLE-L (see last paragraph), WE HAVE HAD VERY
LITTLE PROBLEMS AT COLBY, BUT CONSIDERABLE PROBLEMS AT
OUR GARDEN CITY INSTALLATION. WE BELIEVE THE PROBLEM IS
PREVENTABLE OR AT LEAST MANAGEABLE IN TILLED CULTURES,
BUT ARE UNSURE ABOUT WHAT PROBLEMS UNTILLED CULTURES
SUCH AS ALFALFA WOULD PRESENT.

I WOULD APPRECIATE A NOTE TO ME ***EVEN IF YOU HAVEN'T HAD
A RODENT PROBLEM***, SO THAT I CAN HAVE A UNSCIENTIFIC
SURVEY OF THE EXTENT OF THE PROBLEM, CROPS OR REGIONS
MOST AFFECTED, METHODOLOGIES TRIED AS SOLUTIONS. TO
SAVE ON A LOT OF MISCELLANEOUS MESSAGES TO TRICKLE-L, I
WOULD SUGGEST THAT YOU POST TO ME AT MY ADDRESS AT
BOTTOM OF PAGE AND I WILL THEN SUMMARIZE THE RESULTS
AND COMMENTS TO TRICKLE-L. A PROMPT RESPONSE WOULD BE
APPRECIATED AS I HOPE TO RELAY SOME OF THE INSIGHTS AT A
PRODUCER MEETING THE FIRST WEEK IN MARCH.
FREDDIE LAMM

SUMMARIZED REMARKS FOLLOW:
Gophers may not be that much of a problem even with no rodent
control program. We have over 80 miles of Geoflow (hardwall) hose
in our vineyards buried 18 to 22" in sandy loam soils with emitters
every 3 1/2'. We began our second year with around 17 gopher
strikes, and suffered an additional five or six through the growing
season. The strikes were easy to find and repair, and the soil is
ALWAYS easy to dig in around them (a bit wet though). I have no
complaints about one strike per four miles per year. We had more
problems with surface animals chewing on the vents and end risers
than with gopher attacks, and far far less maintance with than with our
above ground drip systems. I speculate the gophers don't like the
wet enviornment around the hose during the irrigation season, and
would further speculate that the increased irrigation demanded by
alfalfa would discourage their attacks. I would imagine that strikes in
an alfalfa field might be harder to find than in a tilled vineyard, as
they would be disguised by the growing hay.......Craig Thompson

Gopher 'strikes' (a good term by the way) or any kind of break is
difficult to observe in an alfalfa field due to the camouflaging nature of
the crop. The first 'phase' of our alfalfa experiment at Brawley,
California, involved placing the drip laterals at 15 inches (38 cm)
deep, whereby the second phase of the experiment, laterals were
placed 27 inches (69 cm) deep. I do recall several incidences of
gopher strikes during the first (shallower) phase of the study but I
have yet do see (nor hear from our technician) any gopher damage
during the second (deeper) phase . Not being a gopher expert, I would
assume that gophers prefer to live in the upper 1 to 1.5 feet (30-45cm)
of the soil profile, at least in the lower deserts of
California........Richard Mead

Prior to planting, you should use a gopher machine( an old Planet
Junior seeder with a shank with a balled piece of steel at the end to
form a soft burrow @ 12-18 inches beneath the topsoil) . This
machine drops poison seed and is very effective as a preplant in and
especially around a field. It will eliminate @95% of the gophers
within 3 weeks and if used around the field will eliminte migration.......
Anononymous posting

I quote from a study Long Term Biobarriers to Plant and Animal
Intrusion of Uranium Tailings by Cline J.F., Burton F.G., Cataldo D.A.,
Skiens W.E. and Gano K.A. Sept. 1982.
Table A2 Burrowing Depths and Habitat Prefence of Some
Representative Burrowing Mammals (extract)
Species Recorded Tunneling depth in cm
Marmota monax 40 -50 marmot
Cynomys Ludovicianus 91-427 Black tailed prarie dog
Spermophilus townsendi 50-80 ground squirrel
Thomomys bottae 5-35 pocket gopher
Thomomys talpoides 10-30 pocket gopher
Geomys bursarius 23 Plains pocket gopher
Perognathus longimembris 52-62 pocket mouse
Perognathus parvus 35-193 Great Basin pocket mouse
Dipodomys spectabilis 40-50 kangaroo rat
Dipodomys microps 25-45 Banner-tailed kangaroo rat
Dipodomys merriami 26-175+ Merriam's kangaroo rat
Taxidea taxus 150+ badger
(I hope that the table above holds its format through the net)

This supports Richard's argument and our growers' experience.
Those who bury their hard hose more than 18" deep have little gopher
strike problems. I would expect that a hard hose will be resistant to
the pocket mouse..............Rodney (NOT a rodent expert)

I have used infra red technology in large fields with suprisingly low
costs when coupled to other cultural practices. The "strikes" really
stand out and are easily located and dealt with......Robin Franks

Gopher strikes have been discussed quite recently and I claimed that
gopher damage in SSD was quite rare and not a serious problem. I
now have a grower with a serious problem! The drip lines are at 16
inches in sandy soil and drippers are 42 inches apart. The wetted
areas are not joining. Is it reasonable that the gophers avoid the
wetted area around the emitters and are channelled into the dry mid
sections where they strike? Any experts out there?.....Rodney.

My only suggestion is (assuming that the installation is not
permanent) to treat the field and the perimeter with a gopher machine
and poisin seed PRIOR to installation.......Anonymous posting
The question I have is does anyone know of anything that
can be injected into buried system to control gophers. I have friend
that has a system buried at about 20 cm and has alot of gopher hits.
We have sytems buried at 60 cm and have had very little problems. I
would appreciate any help........Leslie

Gophers? Are you surrounded by gopher country? A previous
ranch we farmed was surrounded by desert, ouch. Never ending
problem. Present ranch is not, and we attempt to eradicate.......Steve
Jordan

A few weeks ago I wrote about a client who had severe gopher
problems with SDI at 18 inch depth in sandy soil. Drippers are 42 inch
apart. He was irrigating for 6 hours every second day. He changed to
3 one hour pulses every day. So far the gopher problem has
disappeared. According to all the "experts" I have spoken to gophers
do not like wet soil and this experience seems to support this
hypothesis..........Rodney.

We have two field research sites in Kansas. The one, I control here
at Colby has had very little problems. The other site has had some
damage. I would attribute some of these differences to tillage
practices. I reshape my beds with a primary tillage operation after
corn harvest. The other site has not been as diligent in their efforts in
this regard. At Colby we also take care to remove by hand or till
residue near controls, flushlines, and other obstructions. I had
noticed, long before my involvement with SDI, that in small
conservation tillage research plots, that rodent and large predator
burrowing activity was higher than bare ground in the winter because
of the better habitat. Tilled areas aren't as inviting to
rodents. The other site that has experienced problems has tried to
"ring" their field with poison pellets giving some degree of control. I
think they have also specifically targeted one of their field margins
near an irrigation canal which provides year round habitat for the
rodents. As to your alfalfa question, many of my ideas can't apply. I
have heard anecdotal reports that the round hard drip hose may be
more effective than drip tape. I would also "guess" (and strictly an
uneducated guess) that deeper installations (where appropriate by
crop and soil considerations) would lessen activity, though
intermittent repairs would be more time consuming. Rodent control
prior to installation, is always a recommendation, along with
subsequent preventive measures to reduce infiltration into the area.
Obviously, alfalfa is a tougher situation................Freddie Lamm

FREDDIE
*

Date: 26 Feb 96 11:51:35 CST
From: FLamm@oznet.ksu.edu (Freddie Lamm)
Subject: SDI Technology session following WFOK

THERE ARE PROBABLY NOT TOO MANY TRICKLE-L PEOPLE IN THE
CENTRAL GREAT PLAINS, USA, BUT IF YOU ARE, WE ARE HAVING A
SDI TECHNOLOGY SESSION FOLLOWING A REGIONAL WATER
POLICY MEETING. THIS MEETING IS DESCRIBED BELOW. THE SDI
SESSION IS OPEN TO THE PUBLIC AND FREE OF CHARGE.

FREDDIE
*

There will be a subsurface drip irrigation (SDI) technology session
following the Water and the Future Of Kansas (WFOK) conference
that is being held in Colby, March 5-6, 1996. The theme of the WFOK
conference is "The Great Plains Symposium 1996: The Ogallala
Aquifer.
Contact KSU Continuing Education (913-532-5569) about registration
for the WFOK meeting.
There is ***no registration or costs*** for the followup SDI session
on Wednesday, March 6 at 1:30 pm. This session will last about 2
hours. Speakers at the session will be agricultural
engineers, Freddie Lamm, Gary Clark, Danny Rogers, and
agricultural economist, Dan O'Brien. Talks will be on design and
management, KSU corn research with SDI, and economics of SDI.
The research has been going on for 7 years now and many of the
initial questions and concerns have been and are being addressed.

Weather permitting, a visit to the NWREC research SDI site is
possible for those interested.

For those that might be interested in attending, drop a line to me so I
can get a rough indication of numbers.

Freddie
*

Date: Mon, 26 Feb 1996 20:22:51 +0100
From: Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>
Subject:

GET TRICKLE-L LOG9510

Niceto Munoz | Voice: +34-6-1391000
Citriculture Dept. IVIA | Fax: +34-6-1390240
Apartado Oficial | E-MAIL:nmunyoz@master.ivia.es
46113 Moncada, Valencia, Spain |

Date: Mon, 26 Feb 1996 20:23:11 +0100
From: Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>
Subject:

GET TRICKLE-L LOG9511

Niceto Munoz | Voice: +34-6-1391000
Citriculture Dept. IVIA | Fax: +34-6-1390240
Apartado Oficial | E-MAIL:nmunyoz@master.ivia.es
46113 Moncada, Valencia, Spain |

Date: Mon, 26 Feb 1996 20:23:26 +0100
From: Niceto =?iso-8859-1?Q?Mu=F1oz?= <nmunyoz@master.ivia.es>
Subject:

GET TRICKLE-L LOG9512

Niceto Munoz | Voice: +34-6-1391000
Citriculture Dept. IVIA | Fax: +34-6-1390240
Apartado Oficial | E-MAIL:nmunyoz@master.ivia.es
46113 Moncada, Valencia, Spain |

Date: Mon, 26 Feb 1996 16:14:17 -0600
From: Goldberg <goldberg@eden.com>
Subject: RE: Installation of SDI

------ =_NextPart_000_01BB0466.2EE5AD80
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

Bryant: There are really two types of vibratory plows for installing =
SDI. One of the them, the one you describe in your post, pulls the hose =
through a hole created by a bullet on the plow. This type of plow is to =
be avoided in most situations for many reasons, some of which you have =
listed. The other type of plowing is superior--it involves feeding the =
hose down through the channel in the plow as the tractor moves the plow =
along. In this way, the hose is not stretched, but, rather, pushed down =
into the crevice created by the vibrations. In addition, the wall =
"slicking" around the already laid hose which can occur on wet clay =
soils using the bullet-pull plow can be avoided.

Rick Goldberg

----------
From: W. Bryan Smith[SMTP:WSMTH@prism.clemson.edu]
Sent: Monday, February 26, 1996 10:51 AM
To: Multiple recipients of list
Subject: Re: Installation of SDI

Richard,
Another question in line with your own. As I understand the vibratory
plow concept, the pipe or tubing is first assembled, then attached to =
the
plow and pulled along into the void made by the plow. Dragging this
emitterline or drip tape underground might cause a few problems:

(1) Stretching or even pulling apart the drip line during installation

(2) Clogging emitters or outlets due to the abrasion of the dripline
with the side if the created void

Of course, I guess this could be avoided if the vibratory plow shank =
and
"bullet" were large enough. I would really be interested to hear of any
installations with the vibratory plow method, what type of soils were
involved, and how well the installation turned out. I'm certainly not
against using this method, just curious how it works.

Bryan

=20

W. Bryan Smith Office: 803 276-1091
Area Agent - Water Quality FAX: 803 276-1095
Clemson Extension Service
P.O. Box 160 Email: wsmth
Newberry, SC 29108 Internet: wsmth@.clemson.edu

All opinions are my own and not reflective of the policies of =20
Clemson University or the Cooperative Extension Service.

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------ =_NextPart_000_01BB0466.2EE5AD80--

End of Digest
************************

From ab4el@ab4el.com Tue Feb 27 23:59 EST 1996
Date: Mon, 26 Feb 1996 23:59:59 -0600
Message-Id: <199602272359.ab4el@ab4el.com>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 431 was NOT received

TRICKLE-L digest 431 was NOT received

From root@crcnis1.unl.edu Wed Feb 28 22:12 EST 1996
Date: Wed, 28 Feb 1996 21:01:38 -0600
Message-Id: <199602290301.AA16402@crcnis1.unl.edu>
Errors-To: rmead@asrr.arsusda.gov
Reply-To: <trickle-l@unl.edu>
To: Multiple recipients of list <trickle-l@unl.edu>
Subject: TRICKLE-L digest 432

Contents:
Re: Simpler Question - Tivi's answer (Stephen Rawlins <srawlins@ncw.net>)
Re: Response from new member (gideon oron <gidi@bgumail.bgu.ac.il>)

Date: Tue, 27 Feb 1996 23:48:31 -0800
From: Stephen Rawlins <srawlins@ncw.net>
Subject: Re: Simpler Question - Tivi's answer

Meron is exactly right. As long as the wetted volume is sufficient to
contain the water in one irrigation cycel, the only effect it could have on
the wetted soil surface area. For a closed canopy this would have
practically no affect on ET, but could increase it for an open canopy.

Steve Rawlins
USDA/ARS -- Retired
APPROPRIATE SYSTEMS
(Precision Farming Consultants)
2638 Eastwood Avenue
Richland, WA 99352
Phone 509-627-4943
FAX 509-627-1841
Email srawlins@ncw.net

Date: Wed, 28 Feb 1996 11:16:21 +0200 (IST)
From: gideon oron <gidi@bgumail.bgu.ac.il>
Subject: Re: Response from new member

Dear Steve
The calendar is intended to Prof. Judson Harper vice president
for resaerch of CSU, Ft. Collins Colorad
Thanks for your attention
sisncerely
Gideon Oron
Ben-Gurion University
Israel

End of Digest
************************

Prepared by Steve Modena, AB4EL.
Comments and suggestions to: modena@SunSITE.unc.edu