TRICKLE-L: 199704XX
is the compilation of discussion during Apr 97
via AB4EL Web Digests @ SunSITE
>From owner-TRICKLE-L@crcvms.unl.edu Tue Apr 1 01:02 EST 1997
Date: Tue, 01 Apr 1997 00:00:43 -0600
Subject: TRICKLE-L Digest - 30 Mar 1997 to 31 Mar 1997
There are 4 messages totalling 301 lines in this issue.
Topics of the day:
1. M. Brene reply about emitter spacing.
2. Sand media filter media edge wear - responses #2
3. GDD Crop Coefficients - Follow-up to Howell's Reply -Reply
4. Does sand media wear???
Date: Sun, 30 Mar 1997 22:52:51 -0800
From: Manrique Brenes <mjbrenes@UCDAVIS.EDU>
Subject: Re: M. Brene reply about emitter spacing.
Freddie:
Thanks for the reply, your brain teasers were very good. Your final idea =
is our common goal, no argument on that. The "ideal" system was =
forwarded to put things a little more closer to reality. To answer =
questions like: What is better? Why is it better? When someone with =
limited information (most of us by the way) has to make a decision. Your =
comments are very good for the when is it better?=20
It will be hard to find something that is better all the time, but I =
feel that be setting guidelines of what is better most of the times we =
are getting close.
Manrique Brenes
----------
From: FLamm@OZNET.KSU.EDU[SMTP:FLamm@OZNET.KSU.EDU]
Sent: Sunday, March 30, 1997 8:21 PM
To: TRICKLE-L@crcvms.unl.edu
Subject: M. Brene reply about emitter spacing.
FREDDIE LAMM REPLIED:
M. Brene made many good comments and correctly covered the tradeoffs
between his IDEAL system and what reality presently offers. He has
given these issues some thought and is not seeking a one-size-fits-
all solution.
However,
I do have a few additional comments about a few of his statements.
MANRIQUE BRENES SAID:
It is in general better to have as many emitters as possible. The
more emitters the better the actual water distribution. Here, I
am not talking about EU or CU, I am referring to how well the
actual soil profile is wetted.
FREDDIE LAMM REPLIED: The comments are generally correct, and the
examples were good, BUT even though your thoughts are correct, the
integrating effect of soil water redistibution and water uptake by a
disperse root system CAN BE (BUT, NOT ALWAYS) such a significant
factor that after a point closer emitter spacing becomes a moot
improvement. I realize that's technical nitpicking, but I enjoyed
your thoughts so much, I wanted to jump in.
MANRIQUE BRENES SAID:
I think that the technology to produce low volume emitters with a
resistance to plugging as good any "high" flow emitter has been used
for a long time already and it is therefore hard to justify spacing
that are not on the order of 0.3 m at least, 0.2 m is even better.
FREDDIE LAMM: Once again, I argue with you on this one. In general,
I agree with your good assessment of what's practical. BUT, the
correct emitter spacing is still going to be dictated by the
functioning crop root system zone and the soil characteristics
affecting water redistribution.
Consider these brain teaser examples for thought,
Brain Teaser #1.
We say that one of the advantages of microirrigation is the high
uniformity when in reality microirriagtion is usually non-uniform. A
broadcast application of irrigation is uniform while microirrigation
is usually applied at a point or as a line source. If
spacial uniformity is not a requirement in all directions why would
uniformity at the 0.2 or 0.3 m range be so important?
Brain Teaser #2
You are microirrigating trees spaced on 50 ft squares. Would the
0.2- 0.3 m the best spacing for all soil types?
Brain Teaser #3
You are irrigating a field 20 x 20 ft that is a porous sand
overlaying a relatively impervious clay lens at 2 ft. You have a
scavenger crop that has a very disperse root system that covers most
of the field area. Would a few emitters be almost as good as a
bunch of closely spaced emitters?
Brain Teaser #4
Manriques Brenes becomes the world's recognized expert on
microirrigation. In a speech before the United Nations, Brenes
states "In general the emitter spacing should be in the 0.2 - 0.3 m
range." Richard Mead becomes President-for-life of the small country
of Dripovia and issues a degree that all microirrigation systems must
use a 0.2-0.3 m emitter spacing.
***Alternative ending #1****
Mega dripline manufacturer, ScotchTape revolutionizes the industry
with a new drip tape with its patented non-adhesive flowpath with
0.35 m emitter spacing. The dripline is so cheap, they're
practically giving it away, but President Mead's word is law. Later
that year Dripovia is thrown into chaos as peasant Freddie Lamm leads
a revolt pleading for cheaper irrigation systems. Manrique Brenes
pleads for calm, but it is too late.
****Alternative ending #2****
Peasant Freddie Lamm develops a new SDI technique to
apply an animal-based fertilizer slurry. Since the slurry contains
large particles, large emitters are required necessitating a 0.4
emitter spacing to avoid excessive flowrates. Although Peasant Lamm
is praised by both the Commerce Dept and Environmental Protection
Agency of Dripovia, President Mead is incensed and has Peasant Lamm
thrown into prison as a heretic. Later that year Dripovia is thrown
into chaos as everyone is up to their knees in unused animal-based
fertilizer slurry. Manrique Brenes pleads for calm but it is too late.
***MORAL TO BRAIN TEASER #4: Be careful making general rule-of-thumb
statements that politicians or regulators may incorporate into laws
without incorporating common sense in at the same time.
OBVIOUSLY THIS WAS AN ATTEMPT AT HUMOR. NO OFFENSE IS MEANT,
PARTICULARLY TO **PRESIDENT-FOR-LIFE** RICHARD MEAD. No sense
upsetting the Pres.
Anyway, Manrique Brenes had a lot of good thoughts. My last challenge
is that IN MY OPINION:
The ideal microirrigation system is one that economically and
physically meets its purposes without unduly affecting the
environment.
In my opinion, some of your items are not requirements. Some are
JUST practical or economical constraints that we have to face today.
They may not always fall along those same lines.
But at Dennis Miller says, "Thats just my opinion, I could be wrong?
Freddie
*
**********************************************************************
Freddie R. Lamm * o
Research Agricultural Engineer *** /|\
KSU Northwest Research-Extension Center *****\\
105 Experiment Farm Road *******
Colby, Kansas 67701-1697 *********
Phone: 913-462-6281 ***********
FAX: 913-462-2315 *************
E-Mail: flamm@oznet.ksu.edu It's all downhill from here!
**** There's no domain like OZ, There's no domain like OZ. ****
Date: Mon, 31 Mar 1997 09:18:07 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: Re: Sand media filter media edge wear - responses #2
Two more replies - one with a question:
=============================================
From: grapegrower <grapegrower@earthlink.net>
To: <wsmth@CLEMSON.EDU>
X-PMFLAGS: 34078848 0
I have had to replace the media in my filters 2 times in 11 years.
It was evident that the media was no longer doing the job.
=================================================
To: wsmth@CLEMSON.EDU
From: Wally Menke <wallym@ozemail.com.au>
Subject: Re: Sand media filter media edge wear - responses to date
...
X-PMFLAGS: 34078848 0
>Date: Tue, 25 Mar 1997 08:54:30 -0600
>From: James Prochaska <jnmtexas@startel.net>
>To: wsmth@CLEMSON.EDU
>Subject: Re: Does sand media wear???
>X-PMFLAGS: 34078848 0
>
>You may try thinking about how rock hounds polish rocks. This type
>of tumbling action takes place between sand particles while the unit
>is flushing. One has to consider though, it will take a lot of flushing
>to really grind down the sharp edges. If that much flushing is
>accuring, then I would either add more tanks, change the media more
>often, or better yet, go to disc filtration.
The above comment re disc filters is interesting, as has anyone using
automatic Arkal disc filter systems experienced wear on the disc
faces? I know of a few dealers here who have add to add extra discs into
the filter due to wear. This would no doubt change the filtration level to
be finer as well?
Wally Menke
-- End --
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
Internet: wsmth@clemson.edu
=|===|===|===|===|===|===|===|===|===|===|=
All opinions are my own and not reflective of the
policies of Clemson University or the Cooperative
Extension Service.
Date: Mon, 31 Mar 1997 15:04:23 -0600
From: Joe McFarland <m-mcfarland1@TAMU.EDU>
Subject: GDD Crop Coefficients - Follow-up to Howell's Reply -Reply
Tom, I helped write a chapter several years back for an ASAE
monograph on the use of heat units for insect modeling. Some of the
information may be useful for those who wish to use non-linear heat
unit accumulations or to incorporate day-length into the calculations.
The reference is:
McFarland, M. J., I. R. McCann, and K. S. Kline. 1992. Synthesis and
measurement of temperature for insect models. In: Basics of Insect
Modeling. J. L. Goodenough and J. A. Witz, eds. ASAE. St. Joseph MI.
75-92.
Joe McFarland
Stephenville Research and Extension Center
Rt 2 Box 00
Stephenville TX 76401
m-mcfarland1@tamu.edu
817 968-4144
Date: Mon, 31 Mar 1997 20:16:50 +0000
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Re: Does sand media wear???
Bryan Smith wrote:
>Folks, a question:
>
> In years past, more than one sand media filter representative
>has mentioned to me that the edges of sand media particles "wear"
>very slightly over time. This very slight "wear" apparently
>dulls the edges of the particles, with this subsequent dulling
>decreasing the trapping ability of the media. This in turn was
>one reason for increased backflush frequency requirements over
>time.
After spending 4 1/2 years managing irrigation scheduling and some system
maintenance on more than 20,000 acres of tree crops in the southern San
Joaquin -- mostly using sand media filters, drip and microsprinkler -- I
can say without a doubt that biological "matting" of sand media is the
biggest degrading effect on filter efficiency. Most of these systems were
engineered to give 20 - 24 psi at the microsprinkler head over sets ranging
from 20 - 50 acres. When one 4' diameter filter dropped out of the loop to
backflush the downstream pressure was insufficient to fully lift the sand.
This, combined with months of inactivity during the dormant season would
provide static zones in the media that would clump due to algae and
bacteria.
Upon finishing an 8 to 12 run of chlorine injection into the system at 5 to
10 ppm along with 2 cycles of manually increasing the system backpressure
to 45-50 psi for a 90 second backflush on each kettle we would basically be
back to spec. Head loss across the media returned to normal (2-4 psi) and
we could sustain a 'non-flush' interval as long as any tank filled with new
sand (all No. 20 mesh -- no grading). No difference in plugging in the
field was apparent. Some drip systems were nearly 15 years old with a DU
of 84%.
Blake Sanden
Irrigation Management & Agronomy Farm Advisor, Kern County
1031 S Mt Vernon Ave
Bakersfield, CA 92307
805-868-6218
blsanden@ucdavis.edu
End of TRICKLE-L Digest - 30 Mar 1997 to 31 Mar 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Wed Apr 2 01:03 EST 1997
Date: Wed, 02 Apr 1997 00:02:21 -0600
Subject: TRICKLE-L Digest - 31 Mar 1997 to 1 Apr 1997
There are 2 messages totalling 85 lines in this issue.
Topics of the day:
1. Kc terminology (2)
Date: Tue, 1 Apr 1997 11:44:02 -0800
From: Ken Shackel <kashackel@UCDAVIS.EDU>
Subject: Kc terminology
A question to the group:
A "crop coefficient" (K sub c) is defined as:
(crop consumptive water use)/(reference consumptive water use)
where the reference (in California) is a well irrigated grass crop, and all
water use is expressed in units of length (usually mm) equivalent to water
volume per unit total planted land area. This terminology has the advantage
that the sub for K can be other things (like K sub p for a pan evaporation
reference). Many of us however, are now trying to use deficit irrigation of
one sort or another, which means that we will be applying less than the
calculated crop consumptive water use. We would like to remain fairly
consistent with our terminology, but if there are any errors in our current
estimates of the actual consumptive water use for some crops, then
expressing applied water as a fraction of K sub c may just propagate these
errors. What do people think of a neutral term like K sub a ("applied"), or
sub i ("irrigate")? This would not imply anything about deficit or excess
from actual consumptive use, it would just be [applied
irrigation/ET(reference)].
Ken Shackel
Department of Pomology
University of California
Davis, CA 95616-8683
[note: new area code (530) as of November 1, 1997]
Phone (916) 752-0928
Fax (916) 752-8502
Date: Tue, 1 Apr 1997 14:37:51 -0600
From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
Subject: Re: Kc terminology
Ken:
I don't follow exactly what you are proposing but I wanted to
point out there is already Ks and Ka where Ks represents excess soil
evaporation following rainafall or irrigation and Ka represents a
reducing factor for lower amounts of soil water or stressed crops.
There are various
algorithms to calculate these adjusting K factors in the irrigation
engineering books (ie Design and Operation of Farm Irrigation
Systems, Marvin Jensen, Editor ASAE Monograph #3, 1983, Page 208)
(ie. Management of Farm Irrigation Systems, Hoffman, Howell and
Solomon, Editors, ASAE monograph, Page 162). These ideas have been
around at least since the early 1970s. Sometimes these terms have
been ignored or unused because they aren't always applicable in some
common irrigation scenarios. Soils, climates, irrigation practices,
crops, etc. can have an effect on which algorithms work best for Ka
I'm not sure what you mean about a proposed neutral K term. It would
seem to me you would want it to reflect some criteria that would
allow it to be calculated or calibrated to that criteria. I'm
probably overlooking your meaning.
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 TRICKLE-L Digest - 31 Mar 1997 to 1 Apr 1997
***************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Thu Apr 3 01:02 EST 1997
Date: Thu, 03 Apr 1997 00:01:07 -0600
Subject: TRICKLE-L Digest - 1 Apr 1997 to 2 Apr 1997
There are 6 messages totalling 229 lines in this issue.
Topics of the day:
1. CROP K
2. Kc terminology (4)
3. Disc Permeameters
Date: Wed, 2 Apr 1997 08:48:29 -0500
From: Louis Baumhardt <r-baumhardt@TAMU.EDU>
Subject: CROP K
I think Freddie Lamm's citation;
>>(ie Design and Operation of Farm Irrigation Systems, Marvin
Jensen, Editor ASAE Monograph #3, 1983, Page 208)<<
specifically, Eq.6.29 illustrates very well the alphabet soup that is
used to subscript crop K.
I wonder if calculating crop K at the frequency of irrigation has
been investigated or used in further subscripting K?
R. Louis Baumhardt, Res. Assoc.
Texas Agric. Exp. Station
Rt. 3 Box 219
Lubbock, TX 79401-9757
806-746-6528 FAX
806-746-6101 Voice
r-baumhardt@tamu.edu
Date: Wed, 2 Apr 1997 09:38:58 -0500
From: "Craig A. Storlie" <storlie@AESOP.RUTGERS.EDU>
Subject: Re: Kc terminology
------ =_NextPart_000_01BC3F49.B17F3E40
Ken:
I am also confused by your suggestion. How would errors propogate? If =
you told us you applied water at 75% of kc x ETo and you charted kc and =
ETo we would know exactly how much water was applied. Yes, there are =
errors in ETo and kc estimates, but I don't understand how your =
suggestion alleviates the problem. Maybe you could elaborate.
A new term? Hmm...
Craig Storlie
Rutgers University
------ =_NextPart_000_01BC3F49.B17F3E40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------ =_NextPart_000_01BC3F49.B17F3E40--
Date: Wed, 2 Apr 1997 09:51:46 +0000
From: Grant Cardon <gcardon@CERES.AGSCI.COLOSTATE.EDU>
Subject: Re: Disc Permeameters
Darryl Ross,
There are several chapters (5,6,and 7) in the SSSA Special
Publication #30, Advances in Measurement of Soil Physical Properties:
Bringing Theory into Practice, that deal specifically with the
application of the disc permeameter. They should be of help to you.
Grant E. Cardon
Asst. Professor, Irrigation/Water Quality Management
Colorado State University
Department of Soil and Crop Sciences
Ft. Collins, CO 80523-1170
(970) 491 6235 (voice)
(970) 491 0564 (fax)
gcardon@ceres.agsci.colostate.edu
Date: Wed, 2 Apr 1997 08:41:38 -0800
From: Dean Reynolds <dreynold@WATER.CA.GOV>
Subject: Re: Kc terminology
Ken...You lost me...
Kc or Kp, as you point out, is a coefficient to adjust a reference
evapotranspiration to a crop consumptive use. This tells nothing about
applied water until you know the characteristics of the irrigation
system that is applying the water. I don't understand why deficit
irrigation needs it's own set of Kc's. When to apply what amount
percentage of full ET requirement will depend on stage of
growth..crop..harvest. Aren't these factors specific to crop, year,
soils..etc.?
You refer to error in "our current estimates of the actual consumptive
water use". How is your system going to take error out of the
equation? If you can take out the error we should then be able to take
it out of our Kc values.
When you talk of Ka (applied) or Ki (irrigate) how are you going to
express this? As you said a "length" or depth per unit land area? Is
your Ka/Ki going to be the same for all crop, soil, and irrigation
system types?
Am I missing your point? How will your proposed system work?
Ken Shackel wrote:
>
> A question to the group:
>
> A "crop coefficient" (K sub c) is defined as:
>
> (crop consumptive water use)/(reference consumptive water use)
>
> where the reference (in California) is a well irrigated grass crop, and all
> water use is expressed in units of length (usually mm) equivalent to water
> volume per unit total planted land area. This terminology has the advantage
> that the sub for K can be other things (like K sub p for a pan evaporation
> reference). Many of us however, are now trying to use deficit irrigation of
> one sort or another, which means that we will be applying less than the
> calculated crop consumptive water use. We would like to remain fairly
> consistent with our terminology, but if there are any errors in our current
> estimates of the actual consumptive water use for some crops, then
> expressing applied water as a fraction of K sub c may just propagate these
> errors. What do people think of a neutral term like K sub a ("applied"), or
> sub i ("irrigate")? This would not imply anything about deficit or excess
> from actual consumptive use, it would just be [applied
> irrigation/ET(reference)].
>
> Ken Shackel
> Department of Pomology
> University of California
> Davis, CA 95616-8683
> [note: new area code (530) as of November 1, 1997]
> Phone (916) 752-0928
> Fax (916) 752-8502
--
**************************************************
Dean Reynolds
Associate Land and Water Use Analyst
California Department of Water Resources
3251 S Street
Sacramento, CA 95816 USA
Phone: 916-227-7638
Fax: 916-227-7600
email: dreynold@water.ca.gov
**************************************************
Date: Wed, 2 Apr 1997 09:05:03 -0500
From: Tim1Utah@AOL.COM
Subject: Re: Kc terminology
In the landscape irrigation auditing arena we use Ks for species factor, Kd
for Density factor, and Kmc for microclimate factor. In addtition we use K
sub L for landscape coeficient. Isn't amazing what some Phd's can do with the
alphabet? :)
While we are on a Alphabetical vein. Is it appropriate to use ET sub r in the
place of ET sub o for Reference Evapotranspiration? Thanks Tim
Date: Wed, 2 Apr 1997 16:34:50 +0000
From: Grant Cardon <gcardon@CERES.AGSCI.COLOSTATE.EDU>
Subject: Re: Kc terminology
Et sub r is used for reference when the reference crop is alfalfa and
not a well-watered grass and is becoming more and more popular.
------Tim1Utah wrote:
In the landscape irrigation auditing arena we use Ks for species factor, Kd
for Density factor, and Kmc for microclimate factor. In addtition we use K
sub L for landscape coeficient. Isn't amazing what some Phd's can do with the
alphabet? :)
While we are on a Alphabetical vein. Is it appropriate to use ET sub r in the
place of ET sub o for Reference Evapotranspiration? Thanks Tim
---------------------------
Grant E. Cardon
Asst. Professor, Irrigation/Water Quality Management
Colorado State University
Department of Soil and Crop Sciences
Ft. Collins, CO 80523-1170
(970) 491 6235 (voice)
(970) 491 0564 (fax)
gcardon@ceres.agsci.colostate.edu
End of TRICKLE-L Digest - 1 Apr 1997 to 2 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Fri Apr 4 01:03 EST 1997
Date: Fri, 04 Apr 1997 00:01:53 -0600
Subject: TRICKLE-L Digest - 2 Apr 1997 to 3 Apr 1997
There are 8 messages totalling 447 lines in this issue.
Topics of the day:
1. (Fwd) Re: disk filter media edge wear - response
2. ETr and ETo (2)
3. Crop coefficients
4. K sub abc123xyz
5. Fwd: Schedule
6. GROUNDWATER
7. Sand media wear
Date: Thu, 3 Apr 1997 08:46:26 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: (Fwd) Re: disk filter media edge wear - response
------- Forwarded Message Follows -------
Date: Wed, 02 Apr 1997 22:30:17 -0600
From: James Prochaska <jnmtexas@startel.net>
Reply-to: jnmtexas@startel.net
Organization: JNM Technologies, Inc.
To: wsmth@CLEMSON.EDU
Subject: Re: Sand media filter media edge wear - responses #2
On Disk filter Wear:
I've worked with the disc filters in agriculture for about ten years
now. I'm also working with the industrial division of Arkal Water
Technologies. The idea of "wear" on the discs is unusual when you
consider the velocity of flow through the channels in the discs.
Basically if you spend the time calculating it, you should find laminar
flow, or a relatively low Reynold's number. The cleaning process
separates the discs and jets clean water between them. I don't know of
any situation where the discs actually wore from use. I have seen where
the thinner discs will tear from time to time and be flushed out. The
typical "ag" discs (black, red and yellow) are thicker and normally
don't tear. In my own experience, I've had to add more rings over time
due to a lack of sufficient discs in the beginning. The discs tend to
warp when they are not under compression. Once in the filter they are
compressed significantly. After awhile, they flatten and take up less
space and may require more discs. This is common among the thinner
discs such as the grey and green discs. There is an eteched mark on the
filter spine that indicates the full level for the discs. It is
recommended that when you are first loading new discs, you should add a
few more in anticipation of changes caused by compression.
If the filter is sized properly, I don't see why there would be a
problem. I have seen dealers go beyond the recommended flows in order
to make a sale. This causes a multitude of problems.
If any of your dealers truly have worn discs, please have them send some
to me. I will send them to Arkal for analysis. This is important to us
all. You should get many years of good filtration from the discs. We
realy haven't worn any out yet, but there is always a first.
Even if there is wear after five or ten years, replacing discs will
always be easier than sand. Hope this helps. Call or write if you need
more information. I have access to more information than most ag
dealers.
Jim Prochaska, PE
JNM Technologies, Inc.
1516 Shiloh Ave.
Bryan, TX 77803
409-779-6068 ext. 22
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
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, 3 Apr 1997 10:21:04 -0600
From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
Subject: ETr and ETo
ETr is the reference ET for well watered alfalfa and has been
traditionally used in the western US. However, some agencies are
changing to ETo
ETo is the reference ET for well watered short grass.
The main thing to remember is use the correct Kc for the appropriate
equation.
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: Thu, 3 Apr 1997 09:54:20 -0800
From: Dean Reynolds <dreynold@WATER.CA.GOV>
Subject: Re: ETr and ETo
When using "well watered" alfalfa as your reference crop how is the
drying out period at harvest dealt with? Also the criteria call for an
active growth at all times, therefore, a trimmed grass. How are these
difference accounted for?
dean
Freddie Lamm wrote:
>
> ETr is the reference ET for well watered alfalfa and has been
> traditionally used in the western US. However, some agencies are
> changing to ETo
>
> ETo is the reference ET for well watered short grass.
>
> The main thing to remember is use the correct Kc for the appropriate
> equation.
>
> 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. ------
--
**************************************************
Dean Reynolds
Associate Land and Water Use Analyst
California Department of Water Resources
3251 S Street
Sacramento, CA 95816 USA
Phone: 916-227-7638
Fax: 916-227-7600
email: dreynold@water.ca.gov
**************************************************
Date: Thu, 3 Apr 1997 16:54:47 -0500
From: rbrito@CNPMS.EMBRAPA.BR
Subject: Crop coefficients
Dear List Members:
Regarding the idea of creating new Kc's or modifying existing ones,
I should say that I am somewhat worried about the issue.
First, there are already a number of "K's" with different (and
varied) interpretation, to a point where it becomes necessary to
specifically define how each term is being used on each case. As it was
already mentioned, in the book edited by Jensen there is already a serious
attempt to interprete the various "possibilities". FAO has adopted the term
Reference Evapotranspiration (ETo) in an effort to stop referring to grass
or alfalfa.
The new trend in research now is to eliminate the Kc and to start
measuring crop resistance (r sub c) and aerodynamic resistance (r sub a), in
accordance with the Penman-Monteith model, already officially adopted by FAO
worldwide. By now, it is still very difficult to meadure those resistance,
especially rc, which is based on estomatal resistance.
However, while researchers still don't offer a suitable way to
measure these parameters, I think we should stick to the basic values of Kc,
as defined by FAO, or those specifically developped for local use, and not
to try introducing new sources of misinterpretation to users and then, in a
relatively short time, having to change again to new parameters.
By the way, I fear that the idea proposed by Ken Shackel - of using
the ratio (applied water/ET)- will throw another confusion: this time
between Kc (or Ka) and irrigation efficiency of application. My own attitude
is to avoid introducing new coefficient that are, as many of the others,
merely empirical.
Ricardo Brito
Date: Thu, 3 Apr 1997 09:37:56 -0500
From: "Craig A. Storlie" <storlie@AESOP.RUTGERS.EDU>
Subject: K sub abc123xyz
------ =_NextPart_000_01BC4049.1EA43700
Ken:
I am also confused by your suggestion. How would errors propogate? If =
you told us you applied water at 75% of kc x ETo and you charted kc and =
ETo we would know exactly how much water was applied. Yes, there are =
errors in ETo and kc estimates, but I don't understand how your =
suggestion alleviates the problem. Maybe you could elaborate.
Craig Storlie
Rutgers University
------ =_NextPart_000_01BC4049.1EA43700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------ =_NextPart_000_01BC4049.1EA43700--
Date: Thu, 3 Apr 1997 16:20:20 -0500
From: Tim1Utah@AOL.COM
Subject: Fwd: Schedule
---------------------
Forwarded message:
From: lori@irrigation.org (Lori Brown)
To: Tim1Utah@aol.com
Date: 97-04-03 11:17:15 EST
THE IRRIGATION ASSOCIATION
SCHEDULE OF EDUCATION COURSES
HAWAII
OAHU
ELECTRICAL TROUBLESHOOTING - APRIL 28, 1997
BASIC LANDSCAPE IRRIGATION DESIGN - APRIL 29 - 30, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
THE HAWAII CHAPTER OF THE PROFESSIONAL GROUNDS MANAGEMENT SOCIETY
MAUI
ELECTRICAL TROUBLESHOOTING - MAY 2, 1997
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
HOSTED BY THE C.T.A.H.R. COOPERATIVE EXTENSION
KONA
ELECTRICAL TROUBLESHOOTING - MAY 8, 1997
DRIP IN THE LANDSCAPE - MAY 9, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
IDAHO
BOISE
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
SPONSORED BY THE WATER CONSERVATION COMMITTEE OF THE AMERICAN
WATERWORKS ASSOCIATION
CO-SPONSORED BY THE IDAHO DEPARTMENT OF RESOURCE ENERGY DIVISION
NEW MEXICO
ALBUQUERQUE
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 8 - 9, 1997
SPONSORED BY THE NEW MEXICO IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF ALBUQUERQUE
KANSAS
WITCHITA
BUSINESS OF IRRIGATION CONTRACTING - MAY 19, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF WICHITA
CALIFORNIA
SAN DIEGO
ELECTRICAL TROUBLESHOOTING - JUNE 24, 1997
CAL POLY POMONA
ELECTRICAL TROUBLESHOOTING - JUNE 25, 1997
OAKLAND
ELECTRICAL TROUBLESHOOTING - JUNE 26, 1997
SAN JOSE
ELECTRICAL TROUBLESHOOTING - JUNE 27, 1997
NEBRASKA
OMAHA
ELECTRICAL TROUBLESHOOTING - JULY 24, 1997
SPONSORED BY THE NEBRASKA TURF IRRIGATION ASSOCIATION
HOSTED BY BH&L TURF IRRIGATION SUPPLY
KANSAS
HUTCHINSON
ELECTRICAL TROUBLESHOOTING - JULY 25, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
CO-SPONSORED BY THE KANSAS ASSOCIATION OF NURSERYMEN
HOSTED BY BH&L TURF IRRIGATION SUPPLY
WITCHITA
COMPREHENSIVE IRRIGATION CONTRACTING - SEPTEMBER 15, 1997
BASIC LANDSCAPE IRRIGATION DESIGN - DECEMBER 8-9, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF WICHITA
THE IRRIGATION ASSOCIATION RESERVES THE RIGHT TO CANCEL ANY OR ALL
CLASSES AS NECESSARY.
*FOR GENERAL INFORMATION CONCERNING REGISTRATION FORMS AND INFORMATION
CONTACT:
LORI M. BROWN
EDUCATION MANAGER
PHONE: (703) 573-3551 FAX: (703) 573-1913
ADDITIONAL SITES AND DATES WILL BE FORTHCOMING
Date: Thu, 3 Apr 1997 16:21:56 -0500
From: "Kenneth E. Bannister" <kenbannister@GROUNDWATER.COM>
Subject: GROUNDWATER
PLEASE FORWARD
GROUNDWATER - An Internet Forum
Please join our global discussion group on groundwater and related topics.
There are thousands of members worldwide, from over 60 different countries.
--------------------------------------------------------------
To subscribe to GROUNDWATER send e-mail to:
majordomo@ias.champlain.edu
In the body of the e-mail type the command:
subscribe GROUNDWATER
----------------------------------------------------------------
--------------------------------------------------------------
Kenneth E. Bannister
BANNISTER RESEARCH & CONSULTING
Groundwater Hydrology, Applied Geophysics, Geoscience Information
http://www.groundwater.com kenbannister@groundwater.com
RR1 Box 292, Bridport, Vermont USA 05734
In the middle of every difficulty lies opportunity. (A. Einstein)
--------------------------------------------------------------
Date: Thu, 3 Apr 1997 16:48:42 +0000
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Sand media wear
>Bryan Smith wrote:
>
>>Folks, a question:
>>
>> In years past, more than one sand media filter representative
>>has mentioned to me that the edges of sand media particles "wear"
>>very slightly over time. This very slight "wear" apparently
>>dulls the edges of the particles, with this subsequent dulling
>>decreasing the trapping ability of the media. This in turn was
>>one reason for increased backflush frequency requirements over
>>time.
>
>After spending 4 1/2 years managing irrigation scheduling and some system
>maintenance on more than 20,000 acres of tree crops in the southern San
>Joaquin -- mostly using sand media filters, drip and microsprinkler -- I
>can say without a doubt that biological "matting" of sand media is the
>biggest degrading effect on filter efficiency. Most of these systems were
>engineered to give 20 - 24 psi at the microsprinkler head over sets ranging
>from 20 - 50 acres. Pump pressure ran 35-40. When one 4' diameter filter
>dropped out of the loop to
>backflush the downstream pressure was insufficient to fully lift the sand.
>This, combined with months of inactivity during the dormant season would
>provide static zones in the media that would clump due to algae and
>bacteria.
>
>Upon finishing an 8 to 12 run of chlorine injection into the system at 5 to
>10 ppm along with 2 cycles of manually increasing the system backpressure
>to 45-50 psi for a 90 second backflush on each kettle we would basically be
>back to spec. Head loss across the media returned to normal (2-4 psi) and
>we could sustain a 'non-flush' interval as long as any tank filled with new
>sand (all No. 20 mesh -- no grading). No difference in plugging in the
>field was apparent. Some drip systems were nearly 15 years old with a DU
>of 84%.
>
>Blake Sanden
>Irrigation Management & Agronomy Farm Advisor, Kern County
>1031 S Mt Vernon Ave
>Bakersfield, CA 92307
>805-868-6218
>blsanden@ucdavis.edu
End of TRICKLE-L Digest - 2 Apr 1997 to 3 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sat Apr 5 01:03 EST 1997
Date: Sat, 05 Apr 1997 00:01:47 -0600
Subject: TRICKLE-L Digest - 3 Apr 1997 to 4 Apr 1997
There are 4 messages totalling 749 lines in this issue.
Topics of the day:
1. Job Opening
2. TRICKLE-L Digest - 2 Apr 1997 to 3 Apr 1997
3. ETr and ETo
4. Fwd: Updated Schedule
Date: Fri, 4 Apr 1997 08:59:40 -0500
From: "Craig A. Storlie" <storlie@AESOP.RUTGERS.EDU>
Subject: Job Opening
------ =_NextPart_000_01BC40D6.CE151B40
IRRIDELCO INTERNATIONAL
manufacturers and distributors of irrigation
for the international agricultural market.
Irrigation Application Engineer at New Jersey Headquarters
Duties: Quotation, customer service and design capabilities for drip and =
sprinkler irrigation systems. Knowledge of irrigation products.
Requirements: Spanish, computer literate, CAD experience preferrred. =20
Please send letter of application, curriculum vitae, summary of career =
objectives and three letters of reference. Send to L GIlbert, Irridelco =
International, 440 Sylvan Ave., Englewood Cliffs, NJ 07632, Ph: 201 569 =
3030, Fax: 201 569 9237, Lynnglbert@aol.com
------ =_NextPart_000_01BC40D6.CE151B40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------ =_NextPart_000_01BC40D6.CE151B40--
Date: Fri, 4 Apr 1997 10:05:23 -0600
From: "Terry A. Howell" <tahowell@AG.GOV>
Subject: Re: TRICKLE-L Digest - 2 Apr 1997 to 3 Apr 1997
At 12:01 AM 4/4/97 -0600, you wrote:
>There are 8 messages totalling 447 lines in this issue.
>
>Topics of the day:
>
> 1. (Fwd) Re: disk filter media edge wear - response
> 2. ETr and ETo (2)
> 3. Crop coefficients
> 4. K sub abc123xyz
> 5. Fwd: Schedule
> 6. GROUNDWATER
> 7. Sand media wear
>
>----------------------------------------------------------------------
>
>Date: Thu, 3 Apr 1997 08:46:26 -0500
>From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
>Subject: (Fwd) Re: disk filter media edge wear - response
>
>------- Forwarded Message Follows -------
>Date: Wed, 02 Apr 1997 22:30:17 -0600
>From: James Prochaska <jnmtexas@startel.net>
>Reply-to: jnmtexas@startel.net
>Organization: JNM Technologies, Inc.
>To: wsmth@CLEMSON.EDU
>Subject: Re: Sand media filter media edge wear - responses #2
>
>On Disk filter Wear:
>I've worked with the disc filters in agriculture for about ten years
>now. I'm also working with the industrial division of Arkal Water
>Technologies. The idea of "wear" on the discs is unusual when you
>consider the velocity of flow through the channels in the discs.
>Basically if you spend the time calculating it, you should find laminar
>flow, or a relatively low Reynold's number. The cleaning process
>separates the discs and jets clean water between them. I don't know of
>any situation where the discs actually wore from use. I have seen where
>the thinner discs will tear from time to time and be flushed out. The
>typical "ag" discs (black, red and yellow) are thicker and normally
>don't tear. In my own experience, I've had to add more rings over time
>due to a lack of sufficient discs in the beginning. The discs tend to
>warp when they are not under compression. Once in the filter they are
>compressed significantly. After awhile, they flatten and take up less
>space and may require more discs. This is common among the thinner
>discs such as the grey and green discs. There is an eteched mark on the
>filter spine that indicates the full level for the discs. It is
>recommended that when you are first loading new discs, you should add a
>few more in anticipation of changes caused by compression.
>
>If the filter is sized properly, I don't see why there would be a
>problem. I have seen dealers go beyond the recommended flows in order
>to make a sale. This causes a multitude of problems.
>
>If any of your dealers truly have worn discs, please have them send some
>to me. I will send them to Arkal for analysis. This is important to us
>all. You should get many years of good filtration from the discs. We
>realy haven't worn any out yet, but there is always a first.
>
>Even if there is wear after five or ten years, replacing discs will
>always be easier than sand. Hope this helps. Call or write if you need
>more information. I have access to more information than most ag
>dealers.
>Jim Prochaska, PE
>JNM Technologies, Inc.
>1516 Shiloh Ave.
>Bryan, TX 77803
>
>409-779-6068 ext. 22
>
>
>=|===|===|===|===|===|===|===|===|===|===|=
> W. Bryan Smith
> Area Extension Agent - Irrigation / Water Quality
> Clemson Extension Service
> P.O. Box 160
> Newberry, South Carolina 29108 USA
> Office: 803 276-1091 FAX: 803 276-1095
> 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, 3 Apr 1997 10:21:04 -0600
>From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
>Subject: ETr and ETo
>
>ETr is the reference ET for well watered alfalfa and has been
>traditionally used in the western US. However, some agencies are
>changing to ETo
>
>ETo is the reference ET for well watered short grass.
>
>The main thing to remember is use the correct Kc for the appropriate
>equation.
>
>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: Thu, 3 Apr 1997 09:54:20 -0800
>From: Dean Reynolds <dreynold@WATER.CA.GOV>
>Subject: Re: ETr and ETo
>
>When using "well watered" alfalfa as your reference crop how is the
>drying out period at harvest dealt with? Also the criteria call for an
>active growth at all times, therefore, a trimmed grass. How are these
>difference accounted for?
>
>dean
>
>Freddie Lamm wrote:
>>
>> ETr is the reference ET for well watered alfalfa and has been
>> traditionally used in the western US. However, some agencies are
>> changing to ETo
>>
>> ETo is the reference ET for well watered short grass.
>>
>> The main thing to remember is use the correct Kc for the appropriate
>> equation.
>>
>> 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. ------
>
>--
>**************************************************
>Dean Reynolds
>Associate Land and Water Use Analyst
>California Department of Water Resources
>3251 S Street
>Sacramento, CA 95816 USA
>Phone: 916-227-7638
>Fax: 916-227-7600
>email: dreynold@water.ca.gov
>**************************************************
>
>------------------------------
>
>Date: Thu, 3 Apr 1997 16:54:47 -0500
>From: rbrito@CNPMS.EMBRAPA.BR
>Subject: Crop coefficients
>
> Dear List Members:
> Regarding the idea of creating new Kc's or modifying existing ones,
>I should say that I am somewhat worried about the issue.
> First, there are already a number of "K's" with different (and
>varied) interpretation, to a point where it becomes necessary to
>specifically define how each term is being used on each case. As it was
>already mentioned, in the book edited by Jensen there is already a serious
>attempt to interprete the various "possibilities". FAO has adopted the term
>Reference Evapotranspiration (ETo) in an effort to stop referring to grass
>or alfalfa.
> The new trend in research now is to eliminate the Kc and to start
>measuring crop resistance (r sub c) and aerodynamic resistance (r sub a), in
>accordance with the Penman-Monteith model, already officially adopted by FAO
>worldwide. By now, it is still very difficult to meadure those resistance,
>especially rc, which is based on estomatal resistance.
> However, while researchers still don't offer a suitable way to
>measure these parameters, I think we should stick to the basic values of Kc,
>as defined by FAO, or those specifically developped for local use, and not
>to try introducing new sources of misinterpretation to users and then, in a
>relatively short time, having to change again to new parameters.
> By the way, I fear that the idea proposed by Ken Shackel - of using
>the ratio (applied water/ET)- will throw another confusion: this time
>between Kc (or Ka) and irrigation efficiency of application. My own attitude
>is to avoid introducing new coefficient that are, as many of the others,
>merely empirical.
>
> Ricardo Brito
>
>------------------------------
>
>Date: Thu, 3 Apr 1997 09:37:56 -0500
>From: "Craig A. Storlie" <storlie@AESOP.RUTGERS.EDU>
>Subject: K sub abc123xyz
>
>------ =_NextPart_000_01BC4049.1EA43700
>Content-Type: text/plain; charset="us-ascii"
>Content-Transfer-Encoding: quoted-printable
>
>Ken:
>
> I am also confused by your suggestion. How would errors propogate? If =
>you told us you applied water at 75% of kc x ETo and you charted kc and =
>ETo we would know exactly how much water was applied. Yes, there are =
>errors in ETo and kc estimates, but I don't understand how your =
>suggestion alleviates the problem. Maybe you could elaborate.
>
>Craig Storlie
>Rutgers University
>
>------ =_NextPart_000_01BC4049.1EA43700
>Content-Type: application/ms-tnef
>Content-Transfer-Encoding: base64
>
>eJ8+IhkVAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAENgAQAAgAAAAIAAgABBJAG
>ADQBAAABAAAADAAAAAMAADAEAAAACwAPDgAAAAACAf8PAQAAAG0AAAAAAAAAtTvCwCx3EBqhvAgA
>KypWwhUAAAAzB2IhWA3QEbm2REVTVAAAhIAAAAAAAACBKx+kvqMQGZ1uAN0BD1QCAAAAAHRyaWNr
>bGUtbEB1bmwuZWR1AFNNVFAAdHJpY2tsZS1sQHVubC5lZHUAAAAAHgACMAEAAAAFAAAAU01UUAAA
>AAAeAAMwAQAAABIAAAB0cmlja2xlLWxAdW5sLmVkdQAAAAMAFQwBAAAAAwD+DwYAAAAeAAEwAQAA
>AAwAAAAnVFJJQ0tMRS1MJwACAQswAQAAABcAAABTTVRQOlRSSUNLTEUtTEBVTkwuRURVAAADAAA5
>AAAAAAsAQDoBAAAAAgH2DwEAAAAEAAAAAAAABJs2AQiABwAYAAAASVBNLk1pY3Jvc29mdCBNYWls
>Lk5vdGUAMQgBBIABABAAAABLIHN1YiBhYmMxMjN4eXoA/AQBBYADAA4AAADNBwQAAwAJACUAOAAE
>AEUBASCAAwAOAAAAzQcEAAMACQAlADgABABFAQEJgAEAIQAAADI0MkMzNUUzRkVBQkQwMTFCOUI2
>NDQ0NTUzNTQwMDAwAPQGAQOQBgA0AwAAEgAAAAsAIwAAAAAAAwAmAAAAAAALACkAAAAAAAMANgAA
>AAAAQAA5AEBv1p48QLwBHgBwAAEAAAAQAAAASyBzdWIgYWJjMTIzeHl6AAIBcQABAAAAFgAAAAG8
>QDyezeM1LDCr/hHQubZERVNUAAAAAB4AHgwBAAAABQAAAFNNVFAAAAAAHgAfDAEAAAAaAAAAc3Rv
>cmxpZUBhZXNvcC5ydXRnZXJzLmVkdQAAAAMABhACSxiuAwAHEC8BAAAeAAgQAQAAAGUAAABLRU46
>SUFNQUxTT0NPTkZVU0VEQllZT1VSU1VHR0VTVElPTkhPV1dPVUxERVJST1JTUFJPUE9HQVRFP0lG
>WU9VVE9MRFVTWU9VQVBQTElFRFdBVEVSQVQ3NSVPRktDWEVUT0FOAAAAAAIBCRABAAAAvQEAALkB
>AACMAgAATFpGdYC+VxT/AAoBDwIVAqgF6wKDAFAC8gkCAGNoCsBzZXQyNwYABsMCgzIDxQIAcHJC
>cRHic3RlbQKDM/cC5AcTAoB9CoAIzwnZAoAHCoENsQtgbmcxMDNPFFALChRRC/EgSwnwOgcKhQqG
>AZEgSSBhbSEa4GxzbyAFoG5mAnURsGQgYnkgeUEIYSBzdWdnB5B0gmkCIC4gIEhvB+B6dwhgbBvg
>BJADYBGgIEETUG9wb2dhE9A/yR0wSWYcIiB0BvAb4HMbsB9DYXALUAiQG+B3Bx7BBcAewCA3NSUg
>Am8fMGtjIHggRf5UG1AAcBvgH1IRchPQG+AnIdEiYiIid2UdhWtuSR1hZXgA0HRsHBBo+R1hbXUR
>cCDFINAEICBV1R0hWQeQLB+AaASQJCD/CsAkIB31C4AiFyHRHMIAwLMT0CdhYnUFQBrQZAIg+icF
>QHUicASQE8AiYiVy4xw9GxFsZXYHMCnhJ4IPHlICYBPgHSFNYXliXyQgIqMdpAtgBuByHsEuZRms
>Qy/AaWcGAB+QcrsggQqFUipAHLAeMVUDAOJ2KyFpdHkKjxjIM1UFFTEANbAAAAADABAQAAAAAAMA
>ERAAAAAAQAAHMCDao5Y7QLwBQAAIMEBv1p48QLwBHgA9AAEAAAABAAAAAAAAAPDU
>
>------ =_NextPart_000_01BC4049.1EA43700--
>
>------------------------------
>
>Date: Thu, 3 Apr 1997 16:20:20 -0500
>From: Tim1Utah@AOL.COM
>Subject: Fwd: Schedule
>
>---------------------
>Forwarded message:
>From: lori@irrigation.org (Lori Brown)
>To: Tim1Utah@aol.com
>Date: 97-04-03 11:17:15 EST
>
>THE IRRIGATION ASSOCIATION
>SCHEDULE OF EDUCATION COURSES
>
>
>HAWAII
> OAHU
> ELECTRICAL TROUBLESHOOTING - APRIL 28, 1997
>
> BASIC LANDSCAPE IRRIGATION DESIGN - APRIL 29 - 30, 1997
>
>SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
>THE HAWAII CHAPTER OF THE PROFESSIONAL GROUNDS MANAGEMENT SOCIETY
>
>
> MAUI
> ELECTRICAL TROUBLESHOOTING - MAY 2, 1997
>
> CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
>
>SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
>HOSTED BY THE C.T.A.H.R. COOPERATIVE EXTENSION
>
>
> KONA
> ELECTRICAL TROUBLESHOOTING - MAY 8, 1997
>
> DRIP IN THE LANDSCAPE - MAY 9, 1997
>
>SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
>
>
>IDAHO
> BOISE
> CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
>
> SPONSORED BY THE WATER CONSERVATION COMMITTEE OF THE AMERICAN
> WATERWORKS ASSOCIATION
> CO-SPONSORED BY THE IDAHO DEPARTMENT OF RESOURCE ENERGY DIVISION
>
>
>NEW MEXICO
> ALBUQUERQUE
> CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 8 - 9, 1997
>
>SPONSORED BY THE NEW MEXICO IRRIGATION ASSOCIATION
>HOSTED BY THE CITY OF ALBUQUERQUE
>
>
>
>
>KANSAS
> WITCHITA
> BUSINESS OF IRRIGATION CONTRACTING - MAY 19, 1997
>
>SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
>HOSTED BY THE CITY OF WICHITA
>
>CALIFORNIA
> SAN DIEGO
> ELECTRICAL TROUBLESHOOTING - JUNE 24, 1997
> CAL POLY POMONA
> ELECTRICAL TROUBLESHOOTING - JUNE 25, 1997
> OAKLAND
> ELECTRICAL TROUBLESHOOTING - JUNE 26, 1997
> SAN JOSE
> ELECTRICAL TROUBLESHOOTING - JUNE 27, 1997
>
>
>NEBRASKA
> OMAHA
> ELECTRICAL TROUBLESHOOTING - JULY 24, 1997
>
>SPONSORED BY THE NEBRASKA TURF IRRIGATION ASSOCIATION
>HOSTED BY BH&L TURF IRRIGATION SUPPLY
>
>
>KANSAS
> HUTCHINSON
> ELECTRICAL TROUBLESHOOTING - JULY 25, 1997
>
>SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
>CO-SPONSORED BY THE KANSAS ASSOCIATION OF NURSERYMEN
>HOSTED BY BH&L TURF IRRIGATION SUPPLY
>
> WITCHITA
> COMPREHENSIVE IRRIGATION CONTRACTING - SEPTEMBER 15, 1997
>
> BASIC LANDSCAPE IRRIGATION DESIGN - DECEMBER 8-9, 1997
>
>SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
>HOSTED BY THE CITY OF WICHITA
>
>
>
>THE IRRIGATION ASSOCIATION RESERVES THE RIGHT TO CANCEL ANY OR ALL
>CLASSES AS NECESSARY.
>*FOR GENERAL INFORMATION CONCERNING REGISTRATION FORMS AND INFORMATION
>CONTACT:
>LORI M. BROWN
>EDUCATION MANAGER
>PHONE: (703) 573-3551 FAX: (703) 573-1913
>ADDITIONAL SITES AND DATES WILL BE FORTHCOMING
>
>------------------------------
>
>Date: Thu, 3 Apr 1997 16:21:56 -0500
>From: "Kenneth E. Bannister" <kenbannister@GROUNDWATER.COM>
>Subject: GROUNDWATER
>
> PLEASE FORWARD
>
>
> GROUNDWATER - An Internet Forum
>
>
>Please join our global discussion group on groundwater and related topics.
>
>There are thousands of members worldwide, from over 60 different countries.
>
>--------------------------------------------------------------
>
>To subscribe to GROUNDWATER send e-mail to:
>
>
> majordomo@ias.champlain.edu
>
>
>In the body of the e-mail type the command:
>
>
> subscribe GROUNDWATER
>----------------------------------------------------------------
>--------------------------------------------------------------
> Kenneth E. Bannister
> BANNISTER RESEARCH & CONSULTING
> Groundwater Hydrology, Applied Geophysics, Geoscience Information
> http://www.groundwater.com kenbannister@groundwater.com
> RR1 Box 292, Bridport, Vermont USA 05734
>
> In the middle of every difficulty lies opportunity. (A. Einstein)
>--------------------------------------------------------------
>
>------------------------------
>
>Date: Thu, 3 Apr 1997 16:48:42 +0000
>From: Blake Sanden <blsanden@UCDAVIS.EDU>
>Subject: Sand media wear
>
>>Bryan Smith wrote:
>>
>>>Folks, a question:
>>>
>>> In years past, more than one sand media filter representative
>>>has mentioned to me that the edges of sand media particles "wear"
>>>very slightly over time. This very slight "wear" apparently
>>>dulls the edges of the particles, with this subsequent dulling
>>>decreasing the trapping ability of the media. This in turn was
>>>one reason for increased backflush frequency requirements over
>>>time.
>>
>>After spending 4 1/2 years managing irrigation scheduling and some system
>>maintenance on more than 20,000 acres of tree crops in the southern San
>>Joaquin -- mostly using sand media filters, drip and microsprinkler -- I
>>can say without a doubt that biological "matting" of sand media is the
>>biggest degrading effect on filter efficiency. Most of these systems were
>>engineered to give 20 - 24 psi at the microsprinkler head over sets ranging
>>from 20 - 50 acres. Pump pressure ran 35-40. When one 4' diameter filter
>>dropped out of the loop to
>>backflush the downstream pressure was insufficient to fully lift the sand.
>>This, combined with months of inactivity during the dormant season would
>>provide static zones in the media that would clump due to algae and
>>bacteria.
>>
>>Upon finishing an 8 to 12 run of chlorine injection into the system at 5 to
>>10 ppm along with 2 cycles of manually increasing the system backpressure
>>to 45-50 psi for a 90 second backflush on each kettle we would basically be
>>back to spec. Head loss across the media returned to normal (2-4 psi) and
>>we could sustain a 'non-flush' interval as long as any tank filled with new
>>sand (all No. 20 mesh -- no grading). No difference in plugging in the
>>field was apparent. Some drip systems were nearly 15 years old with a DU
>>of 84%.
>>
>>Blake Sanden
>>Irrigation Management & Agronomy Farm Advisor, Kern County
>>1031 S Mt Vernon Ave
>>Bakersfield, CA 92307
>>805-868-6218
>>blsanden@ucdavis.edu
>
>------------------------------
>
>End of TRICKLE-L Digest - 2 Apr 1997 to 3 Apr 1997
>**************************************************
>
>
*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 (voice) *
* USDA-ARS (806) 356-5750 (fax) *
* P.O. Drawer 10 tahowell@ag.gov (e-mail) *
* 2300 Experiment Station Rd. (shipping) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* ........ Make every drop count! Whose water is it? ....... *
*********************************************************************
Date: Fri, 4 Apr 1997 10:05:34 -0600
From: "Terry A. Howell" <tahowell@AG.GOV>
Subject: Re: ETr and ETo
4/4/97
Trickle-L:
In response to Freddie's and Dean's posts (see below), the idea of reference of ET is difficult to grasp. The concept of "reference ET" was first presented in 1980 at the 2nd National ASAE Irrigation Conference. At that presentation, Dr. Gerald Stanhill, a distinguished scientist from Israel, stood up and challenged the notion and said (I'm paraphrasing from memory nearly 20 years old now), "you have just set back ET science 20 years!" Well, 20 years later we are still at the same point and don't understand reference ET (that includes myself). I'm beginning to believe Dr. Stanhill. Although, his criticism was based on a "miss-communication" and a "miss-understanding" (in my opinion) of the "reference ET" concept.
Reference ET -- whether for alfalfa or grass -- only applies to a "HYPOTHETICAL CROP" [not a real one] with characteristics nearly like the real ones. Reference ET for grass and alfalfa should never be confused with actual ET from grass or alfalfa (the problem with the first presentation of the concept). As such, then "real" grass and "real" alfalfa will have their own Kc curves even when they are "the reference crop"! In my idea there are four significant constants (and many lesser important one) that must be defined (or must be assumed) for a "HYPOTHETIAL" reference crop using a Penman-Monteith equation (ASCE Manual No. 70 for example):
parameter alfalfa grass
albedo 0.23 0.23
emissivity 0.98 0.98
height 0.6 m 0.12 m
rc 70 s/m 70 s/m
"Real" alfalfa or "real" grass is not always exactly these heights, may not always have exactly the specified surface resistance (rc), and may not always have the specified albedo (or even the emissivity). Hence, to find a perfect match between "real alfalfa ET" and "reference alfalfa ET" is impossible (or for grass either)! Research on these topics should be directed to identifying what physical characteristics for the reference crop work the best in a range of environments (and why), and how the actual crop physical characteristics vary and affect actual ET from the "reference species."
To further complicate matters actual ET from a crop is affected by these same physical factors and a few more. At the recent ASAE ET conference, Rick Allen demonstrated for crops that the alfalfa base made more sense (similar aerodynamic properties to a medium to tall crop). But grass reference ET has a better selling point to "urban" audiences for landscape and lawn watering guides. The biggest appeal for a alfalfa reference is that maximum Kc for many crops is at or below 1.0 while they will exceed 1.2--1.3 for a grass reference.
Although I hate to pour fuel on the fire, you may want to check out this web site and learn how to start your barbque and be cooking in less than 3 sec. http://ghg.ecn.purdue.edu/. [note this may only interest the serious outdoor cookers in the crowd!]
Terry Howell
-----------------------------
>>
>>Date: Thu, 3 Apr 1997 10:21:04 -0600
>>From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
>>Subject: ETr and ETo
>>
>>ETr is the reference ET for well watered alfalfa and has been
>>traditionally used in the western US. However, some agencies are
>>changing to ETo
>>
>>ETo is the reference ET for well watered short grass.
>>
>>The main thing to remember is use the correct Kc for the appropriate
>>equation.
>>
>>Freddie
>>*
>>------------------------------
>>
>>Date: Thu, 3 Apr 1997 09:54:20 -0800
>>From: Dean Reynolds <dreynold@WATER.CA.GOV>
>>Subject: Re: ETr and ETo
>>
>>When using "well watered" alfalfa as your reference crop how is the
>>drying out period at harvest dealt with? Also the criteria call for an
>>active growth at all times, therefore, a trimmed grass. How are these
>>difference accounted for?
>>
>>dean
>
*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 (voice) *
* USDA-ARS (806) 356-5750 (fax) *
* P.O. Drawer 10 tahowell@ag.gov (e-mail) *
* 2300 Experiment Station Rd. (shipping) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* ........ Make every drop count! Whose water is it? ....... *
*********************************************************************
Date: Fri, 4 Apr 1997 12:15:06 -0500
From: Tim1Utah@AOL.COM
Subject: Fwd: Updated Schedule
---------------------
Forwarded message:
From: lori@irrigation.org (Lori Brown)
To: Tim1Utah@aol.com (Tim)
Date: 97-04-04 10:28:35 EST
THE IRRIGATION ASSOCIATION
SCHEDULE OF EDUCATION COURSES
HAWAII
OAHU
ELECTRICAL TROUBLESHOOTING - APRIL 28, 1997
BASIC LANDSCAPE IRRIGATION DESIGN - APRIL 29 - 30, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
THE HAWAII CHAPTER OF THE PROFESSIONAL GROUNDS MANAGEMENT SOCIETY
MAUI
ELECTRICAL TROUBLESHOOTING - MAY 2, 1997
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
HOSTED BY THE C.T.A.H.R. COOPERATIVE EXTENSION
KONA
ELECTRICAL TROUBLESHOOTING - MAY 8, 1997
DRIP IN THE LANDSCAPE - MAY 9, 1997
SPONSORED BY THE LANDSCAPE INDUSTRY COUNCIL OF HAWAII
IDAHO
BOISE
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 5 - 6, 1997
SPONSORED BY THE WATER CONSERVATION COMMITTEE OF THE AMERICAN
WATERWORKS ASSOCIATION
THE BUREAU OF RECLAMATION
CO-SPONSORED BY THE IDAHO DEPARTMENT OF WATER RESOURCES
NEW MEXICO
ALBUQUERQUE
CERTIFIED LANDSCAPE IRRIGATION AUDITOR - MAY 8 - 9, 1997
SPONSORED BY THE NEW MEXICO IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF ALBUQUERQUE
KANSAS
WICHITA
BUSINESS OF IRRIGATION CONTRACTING - MAY 19, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF WICHITA
CALIFORNIA
SAN DIEGO
ELECTRICAL TROUBLESHOOTING - JUNE 24, 1997
CAL POLY POMONA
ELECTRICAL TROUBLESHOOTING - JUNE 25, 1997
OAKLAND
ELECTRICAL TROUBLESHOOTING - JUNE 26, 1997
SAN JOSE
ELECTRICAL TROUBLESHOOTING - JUNE 27, 1997
NEBRASKA
OMAHA
ELECTRICAL TROUBLESHOOTING - JULY 24, 1997
SPONSORED BY THE NEBRASKA TURF IRRIGATION ASSOCIATION
HOSTED BY BH&L TURF IRRIGATION SUPPLY
KANSAS
HUTCHINSON
ELECTRICAL TROUBLESHOOTING - JULY 25, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
CO-SPONSORED BY THE KANSAS ASSOCIATION OF NURSERYMEN
HOSTED BY BH&L TURF IRRIGATION SUPPLY
WICHITA
COMPREHENSIVE IRRIGATION CONTRACTING - SEPTEMBER 15, 1997
BASIC LANDSCAPE IRRIGATION DESIGN - DECEMBER 8-9, 1997
SPONSORED BY THE KANSAS IRRIGATION ASSOCIATION
HOSTED BY THE CITY OF WICHITA
THE IRRIGATION ASSOCIATION RESERVES THE RIGHT TO CANCEL ANY OR ALL
CLASSES AS NECESSARY.
*FOR GENERAL INFORMATION CONCERNING REGISTRATION FORMS AND INFORMATION
CONTACT:
LORI M. BROWN
EDUCATION MANAGER
PHONE: (703) 573-3551 FAX: (703) 573-1913
ADDITIONAL SITES AND DATES WILL BE FORTHCOMING
End of TRICKLE-L Digest - 3 Apr 1997 to 4 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Tue Apr 8 01:02 EDT 1997
Date: Tue, 08 Apr 1997 00:01:02 -0600
Subject: TRICKLE-L Digest - 4 Apr 1997 to 7 Apr 1997
There are 3 messages totalling 179 lines in this issue.
Topics of the day:
1. RE ETo debate
2. Motorola Irrigation WWW site survey
3. Deep SDI installation, 2nd Cycle.
Date: Mon, 7 Apr 1997 13:16:10 +0930
From: meissner.tony@WPO.PI.SA.GOV.AU
Subject: RE ETo debate
I have been following with interest the debate on Eto, ETr etc. In my part of Australia, we have been monitoring soil water on commercial
properties for over 10 years now. What is interesting is that when we calculate our water use figures for citrus and vines, our figures are in
good agreement with the FAO figures published in Doorenbos & Pruitt's manuscript (FAO 24). So the work gone into deriving these
figures must have been sound for our figures in Australia to agree closely with the FAO ones.
The trouble is, as highlighted by Terry Howell's last posting is that the concept of ETo, whether a "grass" or " alfalfa", is that it is a
hypothetical, ideal crop. The logical extension of this is, how do we know whether the ETo figures is correct or doesn't matter so long as we
all agree that such a figure is a reference?.
I suspect, as highlighted by the discussion, we do not really understand, what ETo or variants mean, although we all use them to calculate a
water use or predict when to irrigate etc., but we still seem to get approximately the right answer!. Sometimes, we get the sdcientific right
answer mixed up with the practical right answer. In most cases, the errors in the system only lead us to give confidence in the answer of +
or - 10%.
Yours sincerely
Tony Meissner
*********************************************
*Senior Research Scientist (Irrigation) *
*Irrigated Crop Management Service *
*Primary Industries, South Australia *
*Loxton Centre, Loxton SA Aust 5333 *
*Tel: +61 85 95 9146 *
*Fax: +61 85 95 9180 *
*email: meissner.tony@pi.sa.gov.au *
*********************************************
Date: Mon, 7 Apr 1997 09:27:00 -0500
From: Dave Megeath-CIRR03 <Dave_Megeath-CIRR03@EMAIL.MOT.COM>
Subject: Motorola Irrigation WWW site survey
We at Motorola are planning to create an Internet site that will
provide you and some of your customers with technical support. This
has become very popular for companies with technical products.
This site will include Frequently Asked Questions (FAQ), literature,
software upgrades and some applications. Of course, this service will
be available 7 days a week, 24 hours a day. Please answer inside this
form, respond to my address.... cirr03@email.mot.com
The purpose of this questionnaire is to give us an idea of how many of
you are interested in this service.
1. How often do you use Motorola support today?:
[ ] More than once a week
[ ] More than once a month
[ ] Infrequently
2. How satisfied are you with the present methods of supports?:
[ ] Very satisfied
[ ] Moderately satisfied
[ ] Not satisfied
3. By which method(s) would you prefer to receive assistance about
Irrigation
products (can be more than one)?:
[ ] Phone
[ ] Internet
[ ] Email
[ ] Fax
[ ] Other:_____________________________________________
4. If an Internet site for Irrigation products support is available, which
of the following describes how you would use it?:
[ ] Yes, I would use it often.
[ ] Yes, it would have some value.
[ ] No, I don't have Internet capabilities
[ ] No, I have Internet capabilities but prefer other methods of support.
5. If an Internet site for Irrigation products support were available, which
of these
sources would you be likely to use? (Fill in 1-6, where 1 is least,
and 6 is most important):
[ ] Frequently Asked Questions (FAQ).
[ ] On-line documentation (such as Product and System descriptions).
[ ] What's new.
[ ] Sales information
[ ] Training.
[ ] Software upgrades.
6. Will support via the Internet improve your satisfaction from Motorola
support?:
[ ] Very much
[ ] Somewhat
[ ] Not much
7. Other comments:
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
_____________________________________________
Best regards,
Dave Megeath.
---------------------------- Forwarded with Changes ---------------------------
From: OFERS%MOTCOMIL.MCIL@mcilnvl.comm.mot.com*RFC-822*@INTERNET at EMAIL
Date: 4/7/97 5:19AM
To: Megeath Dave CIRR03 at CA05LMPS
Subject: System Planner 97
-------------------------------------------------------------------------------
Date: Mon, 7 Apr 1997 15:28:29 -0500
From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
Subject: Deep SDI installation, 2nd Cycle.
I'm aware of some of the Andros Engineering SDI recovery equipment as
well as some of the surface recovery equipment. However they
probably aren't appropriate at the proposed depths.
Does anyone out there have experience with installing a Deep SDI System
for a second cycle with the following constraints??? Our main questions
relate to mainline, submain, and connector re-use and whether drip
tape would need to be removed.
Drip tape needs replacing for unspecified reason.
Installation depth greater than 16-18 inches
Silt loam soils.
15 mil drip tape.
Main line at frost depth > 32 inches.
Submains at tape depth.
We are NOT contemplating doing this, but for economic analysis
purposes would like to estimate the labor and new equipment
requirement.
Specific questions are:
If the tape is at 16-18 inches and the longevity has been 10-20
years, would there be any physical, legal or philosophical reason to
remove the tape itself?
We think we could reuse the mains, submains and possibly the
connectors by carefully mechanically trenching close to the original
trench and then "caving" off the sidewall to expose the submain and
connectors. This would require more time than an original
installation, but might be cheaper than buying all new submains,
mains and connectors, etc. The drip lateral spacing is 5 ft. Any
ideas about additional time requirements and estimates of the amount
of totally new connectors, submains, etc. that would be required???
We would particularly like to visit with anyone that has attempted
the second cycle with a ****DEEP**** installation. You can send
email directly to me.
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 TRICKLE-L Digest - 4 Apr 1997 to 7 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Wed Apr 9 01:03 EDT 1997
Date: Wed, 09 Apr 1997 00:02:28 -0600
Subject: TRICKLE-L Digest - 7 Apr 1997 to 8 Apr 1997
There are 3 messages totalling 123 lines in this issue.
Topics of the day:
1. Motorola Irrigation WWW site survey (3)
Date: Tue, 8 Apr 1997 08:05:00 -0500
From: Jim Weigel <jweigel@NDSUEXT.NODAK.EDU>
Subject: Re: Motorola Irrigation WWW site survey
At 09:27 AM 4/7/97 -0500, you wrote:
>We at Motorola are planning to create an Internet site that will
>provide you and some of your customers with technical support. This
>has become very popular for companies with technical products.
>
>This site will include Frequently Asked Questions (FAQ), literature,
>software upgrades and some applications. Of course, this service will
>be available 7 days a week, 24 hours a day. Please answer inside this
>form, respond to my address.... cirr03@email.mot.com
>
>The purpose of this questionnaire is to give us an idea of how many of
>you are interested in this service.
>
>1. How often do you use Motorola support today?:
> [ ] More than once a week
> [ ] More than once a month
> [x ] Infrequently
>
>2. How satisfied are you with the present methods of supports?:
> [ ] Very satisfied
> [x ] Moderately satisfied
> [ ] Not satisfied
>
>3. By which method(s) would you prefer to receive assistance about
>Irrigation
> products (can be more than one)?:
> [ ] Phone
> [x ] Internet
> [x ] Email
> [ ] Fax
> [ ] Other:_____________________________________________
>
>4. If an Internet site for Irrigation products support is available, which
>of the following describes how you would use it?:
>
> [ ] Yes, I would use it often.
> [x] Yes, it would have some value.
> [ ] No, I don't have Internet capabilities
> [ ] No, I have Internet capabilities but prefer other methods of support.
>
>5. If an Internet site for Irrigation products support were available, which
>of these
> sources would you be likely to use? (Fill in 1-6, where 1 is least,
> and 6 is most important):
>
> [2 ] Frequently Asked Questions (FAQ).
> [5 ] On-line documentation (such as Product and System descriptions).
> [4 ] What's new.
> [1] Sales information
> [3 ] Training.
> [ 6] Software upgrades.
>
>6. Will support via the Internet improve your satisfaction from Motorola
>support?:
> [ ] Very much
> [ x] Somewhat
> [ ] Not much
>
>7. Other comments:
> _____________________________________________
>
> _____________________________________________
>
> _____________________________________________
>
> _____________________________________________
>
> _____________________________________________
>
>
>Best regards,
>
>Dave Megeath.
>
>---------------------------- Forwarded with Changes ---------------------------
>From: OFERS%MOTCOMIL.MCIL@mcilnvl.comm.mot.com*RFC-822*@INTERNET at EMAIL
>Date: 4/7/97 5:19AM
>To: Megeath Dave CIRR03 at CA05LMPS
>Subject: System Planner 97
>-------------------------------------------------------------------------------
>
>
Jim Weigel (701)652-3194 (701)652-3195 FAX
Area Specialist, Irrigation jweigel@ndsuext.nodak.edu
PO Box 140, Carrington ND 58421
"Whiskey's for drinking; Water's for fighting over" - Mark Twain
Date: Tue, 8 Apr 1997 14:24:16 -0400
From: Lynn Gilbert <Lynnglbert@AOL.COM>
Subject: Re: Motorola Irrigation WWW site survey
is this related to irrigation. If so, what kind, turf or agriculture
Date: Tue, 8 Apr 1997 17:47:00 -0500
From: Jim Weigel <jweigel@NDSUEXT.NODAK.EDU>
Subject: Re: Motorola Irrigation WWW site survey
At 02:24 PM 4/8/97 -0400, you wrote:
>is this related to irrigation. If so, what kind, turf or agriculture
>
>
AG.
Jim Weigel (701)652-3194 (701)652-3195 FAX
Area Specialist, Irrigation jweigel@ndsuext.nodak.edu
PO Box 140, Carrington ND 58421
"Whiskey's for drinking; Water's for fighting over" - Mark Twain
End of TRICKLE-L Digest - 7 Apr 1997 to 8 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Thu Apr 10 01:50 EDT 1997
Date: Thu, 10 Apr 1997 00:01:03 -0600
Subject: TRICKLE-L Digest - 8 Apr 1997 to 9 Apr 1997
There are 4 messages totalling 71 lines in this issue.
Topics of the day:
1. being on list
2. Re[2]: Motorola Irrigation WWW site survey
3. Change in Email Address
4. <No subject given>
Date: Wed, 9 Apr 1997 09:56:08 -0400
From: Lynn Gilbert <Lynnglbert@AOL.COM>
Subject: Re: being on list
please take me off your regular mailing list. We would just like to use it
for your archives. Also we posted a job offering and would like to get the
answers to the offer.
I hope this isn't too inconvenient.
Date: Wed, 9 Apr 1997 06:55:00 -0500
From: Dave Megeath-CIRR03 <Dave_Megeath-CIRR03@EMAIL.MOT.COM>
Subject: Re[2]: Motorola Irrigation WWW site survey
Message authorized by:
: jweigel@NDSUEXT.NODAK.EDU@INTERNET at EMAIL
The MOTOROLA WWW survey is related to our Irrigation Automation
Systems which are used in both AG and TURF irrigation, featuring
comprehensive use of data over radio, and the corresponding
abandonment of underground wires traditionally used for sensing and
control.
______________________________ Reply Separator _________________________________
Subject: Re: Motorola Irrigation WWW site survey
Author: TRICKLE-L@crcvms.unl.edu@INTERNET at EMAIL
Date: 4/8/97 5:47 PM
At 02:24 PM 4/8/97 -0400, you wrote:
>is this related to irrigation. If so, what kind, turf or agriculture
>
>
AG.
Jim Weigel (701)652-3194 (701)652-3195 FAX
Area Specialist, Irrigation jweigel@ndsuext.nodak.edu
PO Box 140, Carrington ND 58421
"Whiskey's for drinking; Water's for fighting over" - Mark Twain
Date: Wed, 9 Apr 1997 14:11:17 -1000
From: William Pyle <AgSystems@MAIL.ORG>
Subject: Change in Email Address
Please note:
you can now reach me at:
AgSystems@Mail.Org
Aloha,
Willy Pyle
Date: Wed, 9 Apr 1997 19:33:18 -0500
From: Kimberly J Qualls <quallsk@ECN.PURDUE.EDU>
Subject: <No subject given>
I would like to cancel my subscription.
Kim Qualls
End of TRICKLE-L Digest - 8 Apr 1997 to 9 Apr 1997
**************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Fri Apr 11 01:04 EDT 1997
Date: Fri, 11 Apr 1997 00:02:46 -0600
Subject: TRICKLE-L Digest - 9 Apr 1997 to 10 Apr 1997
There are 2 messages totalling 103 lines in this issue.
Topics of the day:
1. Does sand media wear???
2. Deep SDI installation, 2nd Cycle.
Date: Thu, 10 Apr 1997 07:56:32 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: Re: Does sand media wear???
To those following the media wear discussion, here's a reference
provided by Jean:
"Properties of South African silica sand used for rapid filtration,"
A.D. Ceronio and J. Haarhoff
This can be found in ISSN 0378-4738
Water SA Vol. 23 No. 1, January 1997, pg 71
Bryan
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
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, 11 Apr 1997 06:57:46 +0300
From: Yossi Ingber <netafim@INTER.NET.IL>
Subject: Re: Deep SDI installation, 2nd Cycle.
An idea for new deep SDI system during installation :
cover the sub-main in the ternch with sand , the type of white sand that
is used the by building industry, it serves two purposes:[1] protects
the connectors from mechanical damage when you cover the trench [2]
excellent sign ten years later when you want to recover your sub-mains
from the ground or re-connect a new system.
Yossi Ingber/ Engineering and Technical Support
Netafim - Irrigation and Drip Sytems
Freddie Lamm wrote:
>
> I'm aware of some of the Andros Engineering SDI recovery equipment as
> well as some of the surface recovery equipment. However they
> probably aren't appropriate at the proposed depths.
>
> Does anyone out there have experience with installing a Deep SDI System
> for a second cycle with the following constraints??? Our main questions
> relate to mainline, submain, and connector re-use and whether drip
> tape would need to be removed.
>
> Drip tape needs replacing for unspecified reason.
> Installation depth greater than 16-18 inches
> Silt loam soils.
> 15 mil drip tape.
> Main line at frost depth > 32 inches.
> Submains at tape depth.
>
> We are NOT contemplating doing this, but for economic analysis
> purposes would like to estimate the labor and new equipment
> requirement.
>
> Specific questions are:
>
> If the tape is at 16-18 inches and the longevity has been 10-20
> years, would there be any physical, legal or philosophical reason to
> remove the tape itself?
>
> We think we could reuse the mains, submains and possibly the
> connectors by carefully mechanically trenching close to the original
> trench and then "caving" off the sidewall to expose the submain and
> connectors. This would require more time than an original
> installation, but might be cheaper than buying all new submains,
> mains and connectors, etc. The drip lateral spacing is 5 ft. Any
> ideas about additional time requirements and estimates of the amount
> of totally new connectors, submains, etc. that would be required???
>
> We would particularly like to visit with anyone that has attempted
> the second cycle with a ****DEEP**** installation. You can send
> email directly to me.
>
> 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 TRICKLE-L Digest - 9 Apr 1997 to 10 Apr 1997
***************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sat Apr 12 02:54 EDT 1997
Date: Sat, 12 Apr 1997 00:03:02 -0600
Subject: TRICKLE-L Digest - 10 Apr 1997 to 11 Apr 1997
There are 4 messages totalling 156 lines in this issue.
Topics of the day:
1. test
2. EC of stored water
3. EC of stored water -Reply (2)
Date: Fri, 11 Apr 1997 09:31:42 -0700
From: Dean Reynolds <dreynold@WATER.CA.GOV>
Subject: test
test
--
**************************************************
Dean Reynolds
Associate Land and Water Use Analyst
California Department of Water Resources
3251 S Street
Sacramento, CA 95816 USA
Phone: 916-227-7638
Fax: 916-227-7600
email: dreynold@water.ca.gov
**************************************************
Date: Fri, 11 Apr 1997 17:49:39 +0100
From: Patrick.Joyce@PROPERTY.CAMCNTY.GOV.UK
Subject: EC of stored water
Dear List!
Does anyone out there know anything about, or can you point me to any
references, concerning natural change in EC over time with stored
Irrigation waters?
A couple of my growers use *mains* water to trickle irrigate
strawberries/cane fruit because the available winter abstracted
surface water comes in at >3dS/m ...Too saline for straws. They each
use about 20000m^3 /year so there is a significant cost issue!
It seems to me that they ought to be blending mains and abstracted
water to achieve an acceptable EC.
However, it did occur to me that if waters are stored for 6 - 18
months biological processes might reduce the EC, due successive algal
flushes, microfauna growth etc. This could be allowed to die and sink
naturally for removal/disposal, or deliberately destroyed, flocced and
removed.
I would be interested in anyones views or experiences as to whether
biological effects can render such borderline waters useful after a
period of storage and filtration. Or would the effects be peripheral
leaving water with still high levels of Na+?
I'd appreciate your thoughts.
Best regards
Patrick
Date: Fri, 11 Apr 1997 13:40:21 -0500
From: "Joseph C. Henggeler" <j-henggeler@TAMU.EDU>
Subject: EC of stored water -Reply
Patrick.Joyce=40PROPERTY.CAMCNTY.GOV.UK wrote:
A) concerning natural change in EC over time with stored Irrigation =
waters?
B) concerning blending waters of different qualities
+++++++++++++
A) If much evaporation occurs during storage, the EC values will climb =
proportionally. Thus as you loose salt to various processes you may at =
the same time increase concentrations if the salt loss is slower than the =
water loss. A case in point was a Class A pan evaporation pan that had =
not been dumped and re-filled again in who knows how long; its EC was 10 =
times the fill up source=27s EC. The good news -- you mentioned Na-- is =
that the SAR value would decrease if precipitation doesn=27t occur because =
of the nature of the equation: Na/(=5BMg+Ca=5D=5E=BD).
My experience with highly saline waters in Texas is that as they pond, =
Cl and SO4 may decrease. However, since salt levels were so high to =
start off with, the water was still bad.
B) Blending (conjunctive use) of waters is discussed in depth in the =
ASCE=27s =2371 Agricultural Salinity Assessment and Management. If ample =
storage is available, the best strategy for most crops is to use the best =
water for germination & early growth, and the worse water later and for =
leaching. I have used this concept and have grown cotton finished off =
with water of EC =3D 15 dS/m for three years in a row. Melons and =
tomatoes can have better storage quality and taste when using more saline =
waters at critical times; perhaps strawberries may respond similarly.
Joe Henggeler
Ft. Stockton, TX
Date: Fri, 11 Apr 1997 14:44:30 -0700
From: "J.D. Oster" <oster@MAIL.UCR.EDU>
Subject: Re: EC of stored water -Reply
If algae and microbes remove entrain enough salt within their cells to
lower the salinity of water, then the process is worth anywhere from 700 to
3000 dollars per acre-ft. This is the cost of removing salt from water
using membranes or distillation.=20
I have doubts algae and microbes can be effect in entraining salt. If they
could concentrate the water within their cells 100 fold, they would occupy
only 1 percent of the storage reservor. This assumes their organic
structures occupy very little space in comparision to the water within
their cells. However, they would all have to live, because once they die,
their decay will release the entrained salt. (At 01:40 PM 4/11/97 -0500,
you wrote:
>Patrick.Joyce@PROPERTY.CAMCNTY.GOV.UK wrote:
>
>A) concerning natural change in EC over time with stored Irrigation
waters?
>
>B) concerning blending waters of different qualities
>+++++++++++++
> A) If much evaporation occurs during storage, the EC values will climb
proportionally. Thus as you loose salt to various processes you may at the
same time increase concentrations if the salt loss is slower than the water
loss. A case in point was a Class A pan evaporation pan that had not been
dumped and re-filled again in who knows how long; its EC was 10 times the
fill up source's EC. The good news -- you mentioned Na-- is that the SAR
value would decrease if precipitation doesn't occur because of the nature
of the equation: Na/([Mg+Ca]^=BD).
>
> My experience with highly saline waters in Texas is that as they pond,
Cl and SO4 may decrease. However, since salt levels were so high to start
off with, the water was still bad.
>
> B) Blending (conjunctive use) of waters is discussed in depth in the
ASCE's #71 Agricultural Salinity Assessment and Management. If ample
storage is available, the best strategy for most crops is to use the best
water for germination & early growth, and the worse water later and for
leaching. I have used this concept and have grown cotton finished off with
water of EC =3D 15 dS/m for three years in a row. Melons and tomatoes can
have better storage quality and taste when using more saline waters at
critical times; perhaps strawberries may respond similarly.
>
> Joe Henggeler
> Ft. Stockton, TX
>
End of TRICKLE-L Digest - 10 Apr 1997 to 11 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Mon Apr 14 01:03 EDT 1997
Date: Mon, 14 Apr 1997 00:02:28 -0600
Subject: TRICKLE-L Digest - 11 Apr 1997 to 13 Apr 1997
There are 2 messages totalling 153 lines in this issue.
Topics of the day:
1. Answers of new subscriber to set questions
2. March archives|Fertigation|California Growers
Date: Sun, 13 Apr 1997 20:21:21 +0200
From: Hugo Latymer <latymer@CTV.ES>
Subject: Answers of new subscriber to set questions
My name is Hugo Latymer and I am owner of a Nursery Garden of ornamental
plants in Mallorca Spain. We employ about 35 wholetime gardeners, mainly
women. We produce a wide list of annuals and perennials. We are 80%
wholesale and 20% retail to any member of the public who comes to the
nursery and pays cash.
All our 30,000sq.m. are under irrigation and about half under structures,
mainly heated greenhouses.For a long time we have injected nitric acid into
the overhead irrigation and added fertilisers to the irrigation waters; the
pH being about 7.6 but very strongly buffered with bicarbonates. All the
water we use comes from two wells with joint output of about 100tons/hr at
a depth of 20m.
When we started 30 yrs ago these wells had an EC of about 0.35 Siemens.
They now stand at about 1.30 S. Though I suspect that this change is
general in the island, I fear that much of the increase in conductivity is
due to our past prodigality with fertiliser-laced, overhead irrigations.
This is perhaps the main reason for our change fron o/head watering to
"drip". But the reduced consumption of fertiliser saves us money too. A
number of plants that we grow do not like overhead watering - Poinsettias
once the bracts redden, and cyclamen that do not appreciate water in the
crown for instance.
We have a number of systems that we have installed.
1) Drip tubes of 1mm. about 50cm. long. Good except that buyers who
collect their own plants tend to pull out the tubes as they wander between
the rows looking for the perfect plant. It surprises me that the 1mm.
trickle tubes do not block. They certainly would if we did not lower the pH
to 5.6. The drip control methods we use, if any, on these trickle tubes
can wait to another day.
2) For larger specimens we use polythene tubes of 25mm. with integral
emiters containing a maze to control output placed at every 40cm. The
plants in 3l. or 5l. pots are lined out every 40cm. at 40cm. intervals and
the tube is run along over the pots. The trick is to put the plants under
the tube from alternate sides. This prevents the tube falling off the pots.
As this system has no microtubes to pull out it is much more robust.
We are installing a computer that automatically provides water with the
correct pH and conductivity.
The frequency with which we water depends mainly on the size of pot. At
least twice a day with 11cm. and once every two days for 5l. We maintain
several semi-wild cats that keep the mice down and I found you by surfing
for Mediterranean plants.
Trickle well,
Hugo Latymer
Date: Sun, 13 Apr 1997 21:20:35 +0000
From: Richard Mead <rmead@CYBERGATE.COM>
Subject: March archives|Fertigation|California Growers
The March archives of Trickle-L are now available. If you are really a
glutton for punishment, you can read the raw archives by sending "get
trickle-l log9703" to "listserv@crcvms.unl.edu" via e-mail (w/out quotes).
However, if you wish to read the Best of Trickle-L during the month of
March, be sure to check out the Microirrigation Forum at
http://www.cybergate.com/~rmead/best.html
Topics discussed in March [followed by category] were:
-Crop Growth curves based upon Growing Degree Days [Cultural practices]
-Emitter spacing of drip tapes [Engineering]
-Growing Alfalfa with buried drip [Effects on crops] & [SDI]
-Sand Media vs. Disk filters [Water Problems]
-Does sand media wear? [Water Problems]
------------------------
I make it a habit to search for any published articles which have anything
to do with drip irrigation (gosh Richard, get a life!). On a recent trip to
the local university library, I came across a fertigation article in the
February 1997 issue of the American Vegetable Grower magazine. The article
stated that a California vegetable grower (broccoli, lettuce and spinach)
had saved about $30,000 per year in fertilizer costs while maintaining the
same yield. The main reason he saved so much was due to a recently
purchased diaphragm fertilizer injector. The fertigation rates were
therefore tied to water flow and not pressure differentials etc. The grower
also used the 1:2:1 rule, meaning that if his irrigation sets were 1 hour,
the first 15 minutes would be "clean" water, followed by 30 minutes of
fertilizer injected water, finishing with 15 minutes of clean water. My
observation of this method is two-fold:
1) The distribution uniformity of fertilizer to the crop is optimized by
using both the diaphragm injector and the 1:2:1 technique.
2) Delivering the fertilizer very frequently is somewhat analogous to the
high frequency nature drip irrigation itself, meaning that one does not
slug water (nor fertilizer) on at higher rate than the crop can take up.
What struck me however, was that the grower maintained 90 ppm of N in the
irrigation water throughout the season and did not taper or decrease that N
level near the end of the vegetable crop season. This is contrary to what
I've always heard. The grower contends that N carry over in the soil at the
end of the season was normal. Is it the nature of the crop (a vegetable)
that constant nutrient rates are better throughout the season than the
"peak, then level off " routine?
I've tried to initiate fertigation discussions before on Trickle-L but was
not successful. Maybe the particulars of this article could spark a few
comments....hmm? Am I off base?
------------------------
Finally, for any California grower out there in cyberspace, I have the
following announcement.
Wanted: A California Grower
The California Irrigation Institute is a non profit corporation which was
founded in 1962 for the purpose of educating those within and outside the
irrigation industry about all facets of irrigation in California. The
whole purpose of the Institute is to hold an annual conference to discuss
various (scientific, political, economic,
Regulatory) aspects of irrigation and drainage.
As a member of the board of directors of the California Irrigation
Institute, I would like to cordially invite California growers interested
in furthering the understanding of irrigation within their state to either
apply for or submit nominations for membership on the CII board of directors.
The governing board of the C.I.I. is composed of growers, water district
personnel, university researchers, consultants and industry
representatives. Presently there is a vacancy for one grower representative.
Board members participate in four planning meetings throughout the year.
Most planning meetings are either in Sacramento or Fresno. However, due to the
busy nature of most growers in the summer, meetings could be arranged
in other areas if necessary. Next years conference will be held in Fresno
(tentatively February 3rd and 4th, 1998).
Grower representation on the board is very important to the C.I.I. If you
are a California grower and would like to participate in a dynamic fashion
to bring together a variety of people and expertise each year to discuss
California water issues, please respond to me personally at
rmead@cybergate.com
The C.I.I. board of directors looks forward to receiving nominations of
either you or a respected colleague.
For more information about the CII, their WWW home page is:
www.cybergate.com/~rmead/cii.html
Sincerely,
Richard Mead
Trickle-L & MIF owner
Member, Board of Directors, California Irrigation Institute
End of TRICKLE-L Digest - 11 Apr 1997 to 13 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Tue Apr 15 04:50 EDT 1997
Date: Tue, 15 Apr 1997 03:49:20 -0600
Subject: TRICKLE-L Digest - 13 Apr 1997 to 14 Apr 1997
There are 4 messages totalling 259 lines in this issue.
Topics of the day:
1. K and ET sub (whatever) (2)
2. K and ET sub(whatever), response (2)
Date: Mon, 14 Apr 1997 08:36:28 -0700
From: Ken Shackel <kashackel@UCDAVIS.EDU>
Subject: K and ET sub (whatever)
Dear everybody,
Many thanks for the comments and discussions, sorry it's taken me so
long to respond. Considering all the comments, and re-reading Burman
et.al.'s ch. 6 in Jensen's book, it strikes me that there may be quite
different ways to think about Kc and its related terms, although some of the
confusion might be just on my part. One general issue is related to the
scale of time that is involved. Burman et.al. first mention "..an overall
daily crop coefficient" when referring to Kc, but I assume that since ET
(reference) can be reliably modeled from weather information, whatever time
frame is used for the reference is appropriate for the corresponding Kc.
Certainly there will be time steps that are appropriate for the reference
system in question, but other than that, this issue may not be of much
theoretical importance. In any case, in the most rigorous sense, once Kc is
defined as the ratio of crop water use to reference water use, (whatever
reference is chosen), then it looks like the term "Kc" can only be used
under conditions where crop water use is actually measured. When we use Kc
(plus other factors related to efficiency) to calculate applied water, for
the sake of simplicity it is tempting to label the factor that we use as
"Kc", even when actual water use was not measured. In an ideal world this
distinction would not be important, but when we apply an irrigation deficit,
perhaps even when we think we are applying full irrigation, the distinction
may be critical. An example of this is Burman et.al.'s eq. 6.29: Kc =
Kcb*Ka + Ks. Here Kcb is the (basal) crop coefficient, Ks is the soil
coefficient, used for periods after rain or irrigation, and Ka is a
coefficient to account for available soil water. The form of the equation
is certainly reasonable, and there is no question that the behavior of an
irrigated crop could be well described by it, but if it is wrong
mechanistically, then problems in defining and using Kc could arise from its
use. For instance, the equation assumes that Kcb will be reduced in
proportion to the reduction in available soil water under all conditions.
>From a plant physiological perspective there are a lot of reasons to suspect
that this wouldn't be the case, and I think Denmead and Shaws 1962 data
(Agron. J. 45:385-390) empirically support that suspicion. That is, if
available soil water is reduced, then under high evaporative demand a crop
may substantially reduce its water use, relative to any given reference,
whereas under lower evaporative demand, crop water use relative to the
reference may be relatively unaffected. One could argue that from a
practical side this type of interaction between Ka and the environment is
not a big deal, because the error at low evaporative demand would be small,
but then we are moving Kc into more of an empirical status. In any case,
the reason why all this gets us into problems with what we mean by Kc is the
question of how it is to be measured (and then used) under these
circumstances. If we determine that the measured Kc under limited soil
water depends on, say, VPD, then do we attribute the interaction to Kcb or
Ka? For that matter, when we see Kc increase after an irrigation, how do we
know how much should be attributed to the soil, versus a possible increase
in the crop canopy water loss component when the local environment is cooler
or more humid? For that matter again, perhaps the Kcb we think we know,
actually involves some water stress effects because the soil is beginning to
dry, so that Kcb might not be correct if we were using something high-tech
like sub-surface drip irrigation (the "high-tech" is just to see if Claude
Phene is listening). I guess all this leads to the notion of Kc as a more
ball-park, fairly empirical ("semi-theoretical"?) value, perhaps even
including some effects of irrigation system efficiency. For instance, if
the water use of a drip irrigated orchard is measured, the fact that water
is applied to only a portion of the root system could cause some water
stress and influence Kc in the same way as the drying between irrigations
might influence Kcb. Hence, if someone could publish the empirical Kc's
they measured as "Kc", then we could just as well lump all the effects we
use to impose our treatments as an "effective" K sub a (applied) or
whatever. Hence my question.
Given all this though, the safe course (for me, anyway) might just be to
take the published Kc's as a given, estimate (ie., make a guess at) system
efficiency, assume the true water use can be calculated, and express all the
treatments as applying a certain percent of calculated ET. This has the
advantage of being a well defined number, and avoids having to deal with the
issue of whether or not the Kc's we have are correct. This last point is
related to what I meant by "propagating errors" when we assume the Kc's we
have are correct, and then estimate adjustment coefficients for them. If
the Kc's include any environmental effects, particularly crop/environment
interaction effects, then we would propagate that effect when we calculated
an adjustment to the Kc. To be honest, I worry about most (perhaps all) of
the Kc's we have, and for that matter, even the ET (reference) values,
because of the possible involvement of interacting plant physiological
factors. Plants might have a positive response (stomatal opening,
photosynthesis, growth, perhaps even canopy water loss rate) to increasing
water availability, until further increases in soil water cause root health
problems. Hence, what we observe as non-water-limiting canopy water use
under any given field conditions, which is where our Kc's are supposed to
come from, may simply reflect the compromise between too much and too little
water for that particular soil. This concern also applies to the reference
crop, and even though a "hypothetical" reference crop calculation (as Terry
Howell points out) can in some sense remove such biological considerations,
there may have been some of these considerations involved in parameterizing
the hypothetical model to real data in the first place. Other than using
plant-based measurements of water potential as independent evidence of
stress (which is what I am doing), the only way I can think of to address
the issue of a possible soil-specificity in Kc and ET (reference) is by
using something like field plants grown in hydroponics. Actually, golf
greens may come close to this, now that I think of it. Does any one know of
reference or crop ET data that has been measured on hydroponic, or otherwise
high water availability without root problems type plants?
Ken Shackel
Department of Pomology
University of California
Davis, CA 95616-8683
[note: new area code (530) as of November 1, 1997]
Phone (916) 752-0928
Fax (916) 752-8502
Date: Mon, 14 Apr 1997 13:18:20 -0500
From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
Subject: Re: K and ET sub (whatever)
Ken, after reading you last posting (4-14-97), I had a few comments.
I think you'd always have to consider Kc as empirical and would
include some of the effects you mention. But I would suspect the
numbers might not be that far off, because doesn't the Central Limit
Theorem from statistics say to the effect that with numerous repeated
samples of an item each containing normally distributed errors that
the mean will be close to the actual value. SOME STATISTICIAN OUT
THERE WILL PROBABLY NAIL ME.
Ka can have more functional shapes than the log form as expressed by
Jensen. It can also accommodate the Denmead and Shaw type reductions
if the form is correct. Please refer to page 163 of ASAE Monograph
"Management of Farm Irrigation Systems, 1990. Besides those
methods I would guess there are others. The forms do make a
difference and as I said in an earlier posting have often been
neglected in full irrigation scheduling. Some of the newer
literature calls Ka a factor related to water stress, not just
related to deficit soil water.
I agree that it is possible to allow a large propagation of errors to
occur if we estimate too many factors and if we don't examine the
amount of error in each one. Ie. It really bothers me that we get
so darn hung up on the accuracy of ET and the Kc and then use a guess
at application efficiency. An error in it easily "swamps" out the
other. You are correct when you say the inaccuracies are more
important as we finetune for precision. What was once a safety
factor may now be an inaccuracy. The problem is assessing the
relative size of the different errors. Hey, with my research
studies with relatively precise management, I cheat by letting
application efficiency be 100% and letting other inaccuracies cover
for me. I can get away with it on my soil and with my experience on
that soil and with certain crops. But I can't say everyone,
everywhere can do it. That's why the numbers are ranges.
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: Mon, 14 Apr 1997 17:36:05 -0700
From: Gerald Robb <jrobb@SPRINTMAIL.COM>
Subject: K and ET sub(whatever), response
Responding to Ken Shackel's response'
In particular he wrote:
>In any case, in the most rigorous sense, once Kc is
>defined as the ratio of crop water use to reference water use, (whatever
>reference is chosen), then it looks like the term "Kc" can only be used
>under conditions where crop water use is actually measured. When we use Kc
>(plus other factors related to efficiency) to calculate applied water, for
>the sake of simplicity it is tempting to label the factor that we use as
>"Kc", even when actual water use was not measured. In an ideal world this
>distinction would not be important, but when we apply an irrigation deficit,
>perhaps even when we think we are applying full irrigation, the distinction
>may be critical. An example of this is Burman et.al.'s eq. 6.29: Kc =
>Kcb*Ka + Ks. Here Kcb is the (basal) crop coefficient, Ks is the soil
>coefficient, used for periods after rain or irrigation, and Ka is a
>coefficient to account for available soil water.
The basal crop coefficient, Kcb, can be determined from this passage.
Using ETc=ETr*Kc and Kc=Kcb*Ka+Ks, solve for Kcb.
(ETc/ETr-Ks)/Ka = Kcb.
If the soil surface is dry during the period in question, Ks=0.
(ETc/ETr)/Ka = Kcb, or (ETc/Ka)/ETr = Kcb.
If you interpret the ETc/Ka as a well watered crop use (Not ET, since
there is no surface evaporation), then Kcb is a well watered crop
water coefficient. A well watered crop coefficient should be universal
for that
crop configuration (say 40" cotton), since the soil influence has been
included
in the inverse of the Ka function, which can be established locally by
looking
at well-watered vs. less-than-well-watered conditions under the same
climatic
demand conditions.
Date: Mon, 14 Apr 1997 19:41:02 -0700
From: Ken Shackel <kashackel@UCDAVIS.EDU>
Subject: Re: K and ET sub(whatever), response
Gerald,
Sorry, but I don't see the point here:
At 05:36 PM 4/14/97 -0700, Gerald Robb <jrobb@SPRINTMAIL.COM> wrote:
>Responding to Ken Shackel's response'
> The basal crop coefficient, Kcb, can be determined from this passage.
> Using ETc=ETr*Kc and Kc=Kcb*Ka+Ks, solve for Kcb.
> (ETc/ETr-Ks)/Ka = Kcb.
> If the soil surface is dry during the period in question, Ks=0.
> (ETc/ETr)/Ka = Kcb, or (ETc/Ka)/ETr = Kcb.
>If you interpret the ETc/Ka as a well watered crop use (Not ET, since there
is no surface evaporation), then Kcb is a well watered crop water
coefficient. A well watered crop coefficient should be universal for that
crop configuration (say 40" cotton), since the soil influence has been
included in the inverse of the Ka function, which can be established locally
by looking at well-watered vs. less-than-well-watered conditions under the
same climatic demand conditions.
Even though you can algebraically solve for Kcb, it dosen't really
get you anywhere. Remember, the factor Ka was put there specifically to
account for how much of a reduction would occur in Kcb if soil water supply
to the plant was limited. When you say to "...interpret the ETc/Ka as a
well watered crop use", you are in conflict with premise of the equation,
unless you are saying to assume Ka=1, in which case ETc/ETr = Kcb, which
only gets you back to where you started.
Ken Shackel
Department of Pomology
University of California
Davis, CA 95616-8683
[note: new area code (530) as of November 1, 1997]
Phone (916) 752-0928
Fax (916) 752-8502
End of TRICKLE-L Digest - 13 Apr 1997 to 14 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Wed Apr 16 01:04 EDT 1997
Date: Wed, 16 Apr 1997 00:03:24 -0600
Subject: TRICKLE-L Digest - 14 Apr 1997 to 15 Apr 1997
There are 2 messages totalling 72 lines in this issue.
Topics of the day:
1. K and ET sub(whatever), response (2)
Date: Tue, 15 Apr 1997 13:54:31 -0700
From: Gerald Robb <jrobb@SPRINTMAIL.COM>
Subject: Re: K and ET sub(whatever), response
Ken Shackel wrote:
>
> Gerald,
> Sorry, but I don't see the point here:
> Even though you can algebraically solve for Kcb, it dosen't really
> get you anywhere. Remember, the factor Ka was put there specifically to
> account for how much of a reduction would occur in Kcb if soil water supply
> to the plant was limited. When you say to "...interpret the ETc/Ka as a
> well watered crop use", you are in conflict with premise of the equation,
> unless you are saying to assume Ka=1, in which case ETc/ETr = Kcb, which
> only gets you back to where you started.
Assuming that you have a functional relationship for Ka(0
Date: Tue, 15 Apr 1997 15:16:24 -0700
From: Gerald Robb <jrobb@SPRINTMAIL.COM>
Subject: Re: K and ET sub(whatever), response
Gerald Robb wrote:
>
> Ken Shackel wrote:
> >
> > Gerald,
> > Sorry, but I don't see the point here:
> > Even though you can algebraically solve for Kcb, it dosen't really
> > get you anywhere. Remember, the factor Ka was put there specifically to
> > account for how much of a reduction would occur in Kcb if soil water supply
> > to the plant was limited. When you say to "...interpret the ETc/Ka as a
> > well watered crop use", you are in conflict with premise of the equation,
> > unless you are saying to assume Ka=1, in which case ETc/ETr = Kcb, which
> > only gets you back to where you started.
>
> Assuming that you have a functional relationship for Ka(0 can look at ETc/Ka as taking measured crop water use and applying the
> inverse relationship to calculate water use for a well watered crop,
> which will be used to calculate a Kcb which should be universal. One
> such Ka function was put forward by Jensen, and was a logarithmic
> function of soil moisture depletion in the 1970's, in addition to your
> reference of Denmead and Shaw. Future use of these Kcb coefficients are
> dependent upon use of the Ka function, but if the functional
> relationships used to model Ka represent the real world then the
> coefficients derived by this method should be good and transferable.
> Kcb coefficients would apply directly(Ka=1) to high frequency irrigation
> methods, like drip, which would have no crop water use reduction due to
> moisture stress.
End of TRICKLE-L Digest - 14 Apr 1997 to 15 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Thu Apr 17 01:05 EDT 1997
Date: Thu, 17 Apr 1997 00:03:44 -0600
Subject: TRICKLE-L Digest - 15 Apr 1997 to 16 Apr 1997
There are 6 messages totalling 354 lines in this issue.
Topics of the day:
1. Fertigation
2. Kc discursion
3. Kc Discussion
4. Hunting for an article on electric motors (2)
5. Efficient electric motors on sinle phase power
Date: Wed, 16 Apr 1997 13:17:24 -0700
From: Jochen Eberhard <Jochen.Eberhard@T-ONLINE.DE>
Subject: Re: Fertigation
Richard Mead wrote:
>
> What struck me however, was that the grower maintained 90 ppm of N in the
> irrigation water throughout the season and did not taper or decrease that N
> level near the end of the vegetable crop season. This is contrary to what
> I've always heard. The grower contends that N carry over in the soil at the
> end of the season was normal. Is it the nature of the crop (a vegetable)
> that constant nutrient rates are better throughout the season than the
> "peak, then level off " routine?
>
> I've tried to initiate fertigation discussions before on Trickle-L but was
> not successful. Maybe the particulars of this article could spark a few
> comments....hmm? Am I off base?
Hallo everybody,
Good idea, here is my comment. To apply the same nitrogen rate
throughout the season is just the easiest way to hand fertigation. Only
the level in the fertilizer tank has to be checked, which can be done by
everybody. To change fertilizer rates means a lot of work and
controlling of the crops visual or with some methods to check plan/soil
nutrition status in oder to reajust fertilizer rates if nessesary.
Running with the same concentration has the philosophy that
transpiration/water uptake of the plant is correlated with the growth
rate. But this is only a general rule. In an early state of the crop the
roots are poorly developed, so nutrient concentration should be as high
as possible. (This is why recommendations for preplant fertilization
rates are often as high as the total nutrient demand of the crop). If
the crop is well established and root density is high, it should be
possible to reduce the fertilizer concentration. - I have just checked
Rick Snyder´s handbook on Greenhouse Tomatoes: In growbags the nutrient
concentration has to be increased with crop development. This indicates
that with high nutrient demand of the plants the uptake rate increases
in correlation to transpiration rate.
I have heard that - independent of growth state - the nutrient
concentration should be increased with low transpiration demand and
decreased with high transpiration demand to maintain a constant uptake
of nutrients by the plants.
I am doing some research on fertigation on tomatoes this year with
several fertigation strategies. Last year I worked on a constant weekly
nitrogen rate which were stopped 4 weeks before the crop was finished
(in this period the growth rate is very limited anyway due to low
temperatures). With high application rates the results were good with
the constant weeekly rate but with low application rates it seemed that
the supply was sufficient from transplanting (into the field) to some
time prior harvesting and the last six weeks of the crop. The time in
between, when fruit load where increased, the plants showed some
nutrient deficiency.
This can be different with other crops like cauliflower, which has
highest nutrient demand in the last couple or so weeks. This usually
results in a very high nitrogen carry over.
But while we learn more about the actual nutrient demand of the specific
crop drip irrigation will provide a chance to supply just the amount of
nutrients the crop will need at the moment.
As you might sense the more I am writing about fertigation the more
confused I get.
So it would be great if many of you tricklers would contribute your
thoughts to fertigation.
_____________________________________________________________
| Jochen Eberhard * * |
| SLFA Versuchsbetriebe ( \ / ) |
| Queckbrunnerhof \ / |
| Dannstadter Str. 91 --- |
| 67105 Schifferstadt (o|o) |
| Germany ( ~~~ ) |
| ( ) |
| Tel: 0049 - 6235 - 2672 ( ) |
| Fax: - - 82741 ( ooO Ooo ) |
| email: Jochen.Eberhard@t-online.de |
|_____________________________________________________________|
Date: Wed, 16 Apr 1997 11:14:28 -0500
From: "Terry A. Howell" <tahowell@AG.GOV>
Subject: Re: Kc discursion
4/16/97
Trickle-L:
I've been following the discussion on Kc values and just re-read all the=
posts to review past information (except I'm never able to read Craig=
Storlie's encoded information). I think this adds fuel to the fire that we=
don't really know much (see my post about reference ET). Although, the Kcb=
approach and the subsequent closer definition for Kc into Kcb, Ks, or Kw or=
what ever alphabet you use (I use Ks for extra "soil" water evaporation and=
Kw as the "water" deficit factor and Kcb for the "crop basal" Kc)=
regardless of how others may have symbolized them [Kc =3D (Kcb*Kw) + Ks in=
my terminology; and ET =3D Kc*ETr where ETr is the reference ET].
Going back to Ken Shackel's original post (Trikle-L digest of 31 Mar.), I=
think you always need some standard of reference for what "full"=
consumptive use may be. ET is made up of two main parts -- T,=
transpiration; and E, soil water evaporation -- and both parts can be=
manipulated some. I know many of my colleagues -- Freddie Lamm and Bill=
Lyle to name a few -- run many of their experiments based on "computed" ET.=
My group (here at Bushland) run our experiments similarly, but we base our=
control on "actual" measured soil water and not computed ET. The=
discrepancy can be significant if there is any bias in the computed ET=
(either in ETr or in the Kc values). I know this would be a difficult=
control strategy for trees and vines. There are draw backs to both=
methods. I know in our case, we have seen our yields approach a max.=
usually as we approach our "fully-irrigated" control level (usually=
irrigating at even 80% of full does not differ in yield much from the=
"Full" ones). I know some of Bill Lyle's and his colleagues' data from=
Lubbock/Halfway/Lamesa don't plateau out in yield until sometimes=
irrigation exceeds ET by 25 to 30% (i.e. irrigating at 125+% of ET). This=
implies that their computed ET may be low (either Kc or ETr or both) and=
sometimes they seem to plateau for other crops (cotton) at 75-80% of ET. =
Full consumptive use (ET) depends on what E is and how T may be influenced=
by E. So I think Ken is right in some of his doubts about interactions. =
Many think you can eliminate E almost entirely by using subsurface drip,=
and I feel it may only be partially reduced and that T may be even be=
increased some. I don't know how ET can be reduced by eliminating E in a=
closed canopy situation. Maybe someone will show me how? =20
I do know from my ET research that it is almost impossible to measure Kcb=
with high frequency irrigation (like drip or center pivots). At best you=
are measuring some new Kcx (who wants to name this critter??) that includes=
some (largely unknown) soil E factor even assuming Kw is near 1.0. =20
I'd like to add an aside on the Denmead and Shaw paper. This study was the=
subject of many thorough graduate student and faculty debates when I was in=
school. It has been criticized because they buried "shallow" soil=
containers (as my memory serves me only about 0.6 m or so). Water=
extraction from "pots" is quite different from natural (and deeper) soil=
profiles. However, I feel our ET data (from deeper lysimeters with soil=
monoliths) would support a DS (Denmead-Shaw) notion that ETc/ETr as a=
function of soil water does have an environmental interaction (VPD and/or=
other factors). We haven't analyzed our Bushland data thoroughly, but=
ETd/ETw -- ETd is a deficit and ETw is well-watered -- is not a monotonic=
decreasing ratio as soil water is depleted because ETr and other factors=
change dynamically (hourly and daily). The trend is downward as soil water=
deficit increases, but two days side by side (almost exactly the same soil=
water less a few mm, of course) can have very different ETd/ETw ratios=
(presumably because of different environments; seems to decline with higher=
ETr as DS would show but maybe not the exact pattern as DS).
Terry Howell =20
=20
*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 (voice) *
* USDA-ARS (806) 356-5750 (fax) *
* P.O. Drawer 10 tahowell@ag.gov (e-mail) *
* 2300 Experiment Station Rd. (shipping) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* ........ Make every drop count! Whose water is it? ....... *
*********************************************************************
Date: Wed, 16 Apr 1997 11:40:31 -0500
From: "Terry A. Howell" <tahowell@AG.GOV>
Subject: Re: Kc Discussion
4/16/97
Trickle-L:
I've been following the discussion on Kc values and just re-read all the=
posts to review past information (except I'm never able to read Craig=
Storlie's encoded information). I think this adds fuel to the fire that we=
don't really know much (see my post about reference ET). Although, the Kcb=
approach and the subsequent closer definition for Kc into Kcb, Ks, or Kw or=
what ever alphabet you use (I use Ks for extra "soil" water evaporation and=
Kw as the "water" deficit factor and Kcb for the "crop basal" Kc)=
regardless of how others may have symbolized them [Kc =3D (Kcb*Kw) + Ks in=
my terminology; and ET =3D Kc*ETr where ETr is the reference ET].
Going back to Ken Shackel's original post (Trikle-L digest of 31 Mar.), I=
think you always need some standard of reference for what "full"=
consumptive use may be. ET is made up of two main parts -- T,=
transpiration; and E, soil water evaporation -- and both parts can be=
manipulated some. I know many of my colleagues -- Freddie Lamm and Bill=
Lyle to name a few -- run many of their experiments based on "computed" ET.=
My group (here at Bushland) run our experiments similarly, but we base our=
control on "actual" measured soil water and not computed ET. The=
discrepancy can be significant if there is any bias in the computed ET=
(either in ETr or in the Kc values). I know this would be a difficult=
control strategy for trees and vines. There are draw backs to both=
methods. I know in our case, we have seen our yields approach a max.=
usually as we approach our "fully-irrigated" control level (usually=
irrigating at even 80% of full does not differ in yield much from the=
"Full" ones). I know some of Bill Lyle's and his colleagues' data from=
Lubbock/Halfway/Lamesa don't plateau out in yield until sometimes=
irrigation exceeds ET by 25 to 30% (i.e. irrigating at 125+% of ET). This=
implies that their computed ET may be low (either Kc or ETr or both) and=
sometimes they seem to plateau for other crops (cotton) at 75-80% of ET. =
Full consumptive use (ET) depends on what E is and how T may be influenced=
by E. So I think Ken is right in some of his doubts about interactions. =
Many think you can eliminate E almost entirely by using subsurface drip,=
and I feel it may only be partially reduced and that T may be even be=
increased some. I don't know how ET can be reduced by eliminating E in a=
closed canopy situation. Maybe someone will show me how?=20
I do know from my ET research that it is almost impossible to measure Kcb=
with high frequency irrigation (like drip or center pivots). At best you=
are measuring some new Kcx (who wants to name this critter??) that includes=
some (largely unknown) soil E factor even assuming Kw is near 1.0.=20
I'd like to add an aside on the Denmead and Shaw paper. This study was the=
subject of many thorough graduate student and faculty debates when I was in=
school. It has been criticized because they buried "shallow" soil=
containers (as my memory serves me only about 0.6 m or so). Water=
extraction from "pots" is quite different from natural (and deeper) soil=
profiles. However, I feel our ET data (from deeper lysimeters with soil=
monoliths) would support a DS (Denmead-Shaw) notion that ETc/ETr as a=
function of soil water does have an environmental interaction (VPD and/or=
other factors). We haven't analyzed our Bushland data thoroughly, but=
ETd/ETw -- ETd is a deficit and ETw is well-watered -- is not a monotonic=
decreasing ratio as soil water is depleted because ETr and other factors=
change dynamically (hourly and daily). The trend is downward as soil water=
deficit increases, but two days side by side (almost exactly the same soil=
water less a few mm, of course) can have very different ETd/ETw ratios=
(presumably because of different environments; seems to decline with higher=
ETr as DS would show but maybe not the exact pattern as DS).
Terry Howell =20
*********************************************************************
* Terry A. Howell, Ph.D., P.E. (806) 356-5746 (voice) *
* USDA-ARS (806) 356-5750 (fax) *
* P.O. Drawer 10 tahowell@ag.gov (e-mail) *
* 2300 Experiment Station Rd. (shipping) *
* Bushland, TX 79012 http://www.net.usda.gov/cprl/ (Internet) *
* ........ Make every drop count! Whose water is it? ....... *
*********************************************************************
Date: Wed, 16 Apr 1997 10:52:08 +0100
From: Bret Scaliter <bscaliter@MAIL.AIP.COM>
Subject: Hunting for an article on electric motors
Trickle-L Members:
I am desperataely seeking an article on electric motors for the upcoming
issue of "Irrigation Journal." The deadline is April 23rd so time is of
the essence. Does anyone have an article on the subject or know someone
who does and would be interested in having it published? The word
length can run from 1000 to 2000 words. If there is artwork or photos
we can run with the article that would be a plus. The article itself
can address electric motors vis a vis pumps or lateral move or anything
that is apropos to agricultural usage. If you're interested, please let
me know as soon as possible. You can reach me through Trickle-L or by
phone at (760) 770-4370.
Thank you.
Bret Scaliter
Date: Wed, 16 Apr 1997 14:43:49 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: Re: Hunting for an article on electric motors
Bret,
You may have already done this one, but ....
How about an update on the written pole electric motor? The last
information I have is that it was a new technology that would allow
the use of up to 100 horsepower electric motors (!) on single-phase
electric service lines. The motor apparently has a much lower starting
current than traditional electric motors.
The note I have is from the Electric Power Research Institute
(EPRI), technical information phone number (415) 855-2411,
ordering phone number (510) 934-4212. The note I have is dated
August 1994 ( final report is listed as 84 pages, report number
EPRI TR-104072, June, 1994 and costs $200.00). You may also
find them at :
EPRI Distribution Center
207 Coggins Drive
P.O. Box 23205
Pleasant Hill, CA 94523
(510) 934-4212
I would certanily be interested in seeing how these motors have
progressed in the marketplace (if indeed they have) and what their
relative cost is to traditional motors or compared with the use of a
phase converter setup.
Hope this helps!
Bryan
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
Internet: wsmth@clemson.edu
=|===|===|===|===|===|===|===|===|===|===|=
All opinions are my own and not reflective of the
policies of Clemson University or the Cooperative
Extension Service.
Date: Wed, 16 Apr 1997 14:41:25 -0600
From: "OSU Malheur Exp. Station" <mesosu@PRIMENET.COM>
Subject: Efficient electric motors on sinle phase power
Bryan Smith suggests an article on efficient stable motors with low
current start up on single phase power. An effective option is the 1994
and 1996 patents of Dr Otto J. M. Smith that was installed
experimentally here last summer.
Contact Dr. Otto J. M. Smith (retired from the Electrical Engineering
Department, U. C. Berkeley)
612 Euclid Ave.
Berkeley, CA, 94708
(510) 525-9126
Clint
--
Dr. Clinton C. Shock
Malheur Experiment Station
Oregon State University
595 Onion Ave.
Ontario, Oregon 97914
telephone (541) 889-2174
Fax (541) 889-7831
http://www.primenet.com/~mesosu/index.html
End of TRICKLE-L Digest - 15 Apr 1997 to 16 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Fri Apr 18 01:04 EDT 1997
Date: Fri, 18 Apr 1997 00:02:46 -0600
Subject: TRICKLE-L Digest - 16 Apr 1997 to 17 Apr 1997
There are 3 messages totalling 83 lines in this issue.
Topics of the day:
1. Double Posting
2. Efficient, stable, low current motors on single phase power (2)
Date: Thu, 17 Apr 1997 08:34:49 -0500
From: "Terry A. Howell" <tahowell@AG.GOV>
Subject: Double Posting
4/17/97
Trickle-L:
Sorry about my "Double Posting" yesterday. My first one had a mail delivery error, and I assumed that it did not make it.
Terry
Date: Thu, 17 Apr 1997 09:32:56 -0600
From: Clint Shock <mesosu@PRIMENET.COM>
Subject: Efficient, stable, low current motors on single phase power
> Sender: Trickle-L Discussion List
> To: TRICKLE-L@crcvms.unl.edu
> Reply-to: mesosu@PRIMENET.COM
Bryan Smith suggests an article on efficient stable motors with low
current start up on single phase power. An effective option is the 1994
and 1996 patents of Dr Otto J. M. Smith that was installed
experimentally here last summer.
Contact Dr. Otto J. M. Smith (retired from the Electrical Engineering
Department, U. C. Berkeley)
612 Euclid Ave.
Berkeley, CA, 94708
(510) 525-9126
Clint
Dr. Clinton C. Shock
Malheur Experiment Station
Oregon State University
595 Onion Ave.
Ontario, Oregon 97914
telephone (541) 889-2174
Fax (541) 889-7831
http://www.primenet.com/~mesosu/index.html
Date: Thu, 17 Apr 1997 16:55:30 -0600
From: Clint Shock <mesosu@PRIMENET.COM>
Subject: Efficient, stable, low current motors on single phase power
Bryan Smith suggests an article on efficient stable motors with low
current start up on single phase power. An effective option is the 1994
and 1996 patents of Dr Otto J. M. Smith that was installed
experimentally here last summer.
Contact Dr. Otto J. M. Smith (retired from the Electrical Engineering
Department, U. C. Berkeley)
612 Euclid Ave.
Berkeley, CA, 94708
(510) 525-9126
Clint
--
Dr. Clinton C. Shock
Malheur Experiment Station
Oregon State University
595 Onion Ave.
Ontario, Oregon 97914
telephone (541) 889-2174
Fax (541) 889-7831
http://www.primenet.com/~mesosu/index.html
End of TRICKLE-L Digest - 16 Apr 1997 to 17 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sat Apr 19 01:04 EDT 1997
Date: Sat, 19 Apr 1997 00:03:15 -0600
Subject: TRICKLE-L Digest - 17 Apr 1997 to 18 Apr 1997
There is one message totalling 116 lines in this issue.
Topics of the day:
1. Fertigation -- P & micronutrient availability
Date: Fri, 18 Apr 1997 20:56:20 -0600
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Re: Fertigation -- P & micronutrient availability
Tricklers:
I appreciate Richard's efforts to stimulate fertigation discussion and the
comments by Jochen. N utilization is the big question for
water/environmental quality, but I find that growers using micro systems do
a fairly reasonable job with this nutrient when they have a feel for the
root volume wetted by the system and total N demand for the season. N
transformation and availability is more constant over a wide pH and
moisture range than say P and many of the micronutrients. This latter area
is of great interest to me and the growers of the San Joaquin Valley.
HERE'S THE QUESTION: In terms of uptake efficiency on a pound for pound
applied basis, are P, Fe, Cu, and Zn more available when applied to a
saturated zone under a drip emitter or in non-saturated conditions as with
microsprinklers? Is a high concentration 'slug' 3 to 4 times a year
advantageous (tree crops for example) when using phosphoric acid or low
continuous dosage the way to go. What about the 'humic acid craze'? Some
of our Kern County grower's permanent crop fertigation programs are costing
$200/ac?
A four year study in 10 to 14 year old pistachios on a heavy clay loam
comparing drip to mrosprinklers using liquid Urea ammonium nitrate and
green phosphoric acid on a four shot 'slug' program showed no significant
difference in yields or foliar nutrient status between the two systems.
But this was excellent ground to begin with. Let's hear it , Folks!
Blake Sanden
Irrigation Management & Agronomy Farm Advisor, Kern County
1031 S Mt Vernon Ave
Bakersfield, CA 92307
805-868-6218
blsanden@ucdavis.edu
>Richard Mead wrote:
>>
>> What struck me however, was that the grower maintained 90 ppm of N in the
>> irrigation water throughout the season and did not taper or decrease that=
N
>> level near the end of the vegetable crop season. This is contrary to what
>> I've always heard. The grower contends that N carry over in the soil at t=
he
>> end of the season was normal. Is it the nature of the crop (a vegetable)
>> that constant nutrient rates are better throughout the season than the
>> "peak, then level off " routine?
>>
>> I've tried to initiate fertigion dcussions before on Trickle-L but wa=
s
>> not successful. Maybe the particulars of this article could spark a few
>> comments....hmm? Am I off base?
>
>Hallo everybody,
>Good idea, here is my comment. To apply the same nitrogen rate
>throughout the season is just the easiest way to hand fertigation. Only
>the level in the fertilizer tank has to be checked, which can be done by
>everybody. To change fertilizer rates means a lot of work and
>controlling of the crops visual or with some methods to check plan/soil
>nutrition status in oder to reajust fertilizer rates if nessesary.
>Running with the same concentration has the philosophy that
>transpiration/water uptake of the plant is correlated with the growth
>rate. But this is only a general rule. In an early state of the crop the
>roots are poorly developed, so nutrient concentration should be as high
>as possible. (This is why recommendations for preplant fertilization
>rates are often as high as the total nutrient demand of the crop). If
>the crop is well established and root density is high, it should be
>possible to reduce the fertilizer concentration. - I have just checked
>Rick Snyder=B4s handbook on Greenhouse Tomatoes: In growbags the nutrient
>concentration has to be increased with crop development. This indicates
>that with high nutrient demand of the plants the uptake rate increases
>in correlation to transpiration rate.
>I have heard that - independent of growth state - the nutrient
>concentration should be increased with low transpiration demand and
>decreased with high transpiration demand to maintain a constant uptake
>of nutrients by the plants.
>I am doing some research on fertigation on tomatoes this year with
>several fertigation strategies. Last year I worked on a constant weekly
>nitrogen rate which were stopped 4 weeks before the crop was finished
>(in this period the growth rate is very limited anyway due to low
>temperatures). With high application rates the results were good with
>the constant weeekly rate but with low application rates it seemed that
>the supply was sufficient from transplanting (into the field) to some
>time prior harvesting and the last six weeks of the crop. The time in
>between, when fruit load where increased, the plants showed some
>nutrient deficiency.
>This can be different with other crops like cauliflower, which has
>highest nutrient demand in the last couple or so weeks. This usually
>results in a very high nitrogen carry over.
>But while we learn more about the actual nutrient demand of the specific
>crop drip irrigation will provide a chance to supply just the amount of
>nutrients the crop will need at the moment.
>As you might sense the more I am writing about fertigation the more
>confused I get.
>So it would be great if many of you tricklers would contribute your
>thoughts to fertigation.
> _____________________________________________________________
>| Jochen Eberhard * * |
>| SLFA Versuchsbetriebe ( \ / ) |
>| Queckbrunnerhof \ / |
>| Dannstadter Str. 91 --- |
>| 67105 Schifferstadt (o|o) |
>| Germany ( ~~~ ) |
>| ( ) |
>| Tel: 0049 - 6235 - 2672 ( ) |
>| Fax: - - 82741 ( ooO Ooo ) |
>| email: Jochen.Eberhard@t-online.de |
>|_____________________________________________________________|
End of TRICKLE-L Digest - 17 Apr 1997 to 18 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sun Apr 20 01:02 EDT 1997
Date: Sun, 20 Apr 1997 00:01:31 -0600
Subject: TRICKLE-L Digest - 18 Apr 1997 to 19 Apr 1997
There are 2 messages totalling 51 lines in this issue.
Topics of the day:
1. RV: Corruption of ground water by fertilisers.
2. Corruption of groundwaters
Date: Sat, 19 Apr 1997 12:50:29 +0200
From: Hugo Latymer <latymer@CTV.ES>
Subject: RV: Corruption of ground water by fertilisers.
----------
>
>
> The groundwater here in Mallorca, Spain is becoming progressively
> contaminated by the enormous quantity of fertilisers used by farmers and
(I
> must confess) by me. This is quite apart from the overuse of the
> groundwater reserves causing problems with infiltration of sea water. We
> have gone over to drip as much as we can on the Nursery and must be
wasting
> less than 1/3rd of the fertilisers that we used to.
> It would be interesting to know whether all this wasted fertiliser
> (largely N) has caused problems in California, (I have read that it has),
> where I can find the pertinent legislation and how the matter is being
> dealt with there.
> It would be kind to elaborate.
>
> Hugo Latymer
Date: Sat, 19 Apr 1997 23:31:47 +0200
From: Hugo Latymer <latymer@CTV.ES>
Subject: Corruption of groundwaters
For Clint Shock.
Clint,
I'm new to the net and making a hash of it so have to answer here instead
of directly to you having wiped out your address! Many thanks for your
reply. I was wondering whether there are any sources that you know about on
the web that will give the laws or rules, (State, County or whatever) that
try to prevent the perverting of groundwaters? It is going to become a real
problem here as the N levels at the nursery were nearly five times those
stipulated by the EEC as maximum though they are now falling as the result
of dripping rather than squirting! And I'm sure we are cherubs compared to
some.
Anyway. Many thanks:- Hugo
End of TRICKLE-L Digest - 18 Apr 1997 to 19 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Thu Apr 24 01:05 EDT 1997
Date: Thu, 24 Apr 1997 00:03:14 -0600
Subject: TRICKLE-L Digest - 19 Apr 1997 to 23 Apr 1997
There is one message totalling 22 lines in this issue.
Topics of the day:
1. Fertigation in blueberries
Date: Wed, 23 Apr 1997 11:21:50 -0400
From: MSorren175@AOL.COM
Subject: Fertigation in blueberries
I'm looking for fertigation recommendations for 2 year old blueberries. A
drip system will be installed this spring using 1 gph emitters 24" spacing.
Design pressure is 45psi at PRV and flow rate for zone is 300gpm. The grower
requested recommendations on the type of fertilizer to apply, the rate of
application, fertilizer injection schedule, chemigation for weeds, nematodes,
ants etc. Also any info on liming through the system to raise pH from 3.8 to
4.8. There have been problems with very low pH soils on some blueberry fields
but not associated with drip irrigation. If there is any experiences, advice,
and recommendations that can be passed on to NJ blueberry growers, it would
be very helpful.
MaryBeth Sorrentino
Water Management Specialist
USDA, Natural Resources Conservation Service
New Jersey
End of TRICKLE-L Digest - 19 Apr 1997 to 23 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Fri Apr 25 01:05 EDT 1997
Date: Fri, 25 Apr 1997 00:03:26 -0600
Subject: TRICKLE-L Digest - 23 Apr 1997 to 24 Apr 1997
There are 5 messages totalling 265 lines in this issue.
Topics of the day:
1. Micronutrients and drip
2. Economic irrigation application amounts ... (2)
3. change of e-mail address - Hugh Campbell
4. Economic irrigation
Date: Thu, 24 Apr 1997 08:50:55 +0000
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Micronutrients and drip
Tricklers:
I'm a little out of sink (ie. old discussion) with this comment but I've
been having problems with "undelivered mail". So I'm trying again.
I appreciate Richard's efforts to stimulate fertigation discussion and
the
comments by Jochen. N utilization is the big question for
water/environmental quality, but I find that growers using micro systems
do
a fairly reasonable job with this nutrient when they have a feel for the
root volume wetted by the system and total N demand for the season. N
transformation and availability is more constant over a wide pH and
moisture range than say P and many of the micronutrients. This latter
area
is of great interest to me and the growers of the San Joaquin Valley.
HERE'S THE QUESTION: In terms of uptake efficiency on a pound for pound
applied basis, are P, Fe, Cu, and Zn more available when applied to a
saturated zone under a drip emitter or in non-saturated conditions as
with
microsprinklers? Is a high concentration 'slug' 3 to 4 times a year
advantageous (tree crops for example) when using phosphoric acid or low
continuous dosage the way to go. What about the 'humic acid craze'?
Some
of our Kern County grower's permanent crop fertigation programs are
costing
$200/ac?
A four year study in 10 to 14 year old pistachios on a heavy clay loam
comparing drip to mrosprinklers using liquid Urea ammonium nitrate and
green phosphoric acid on a four shot 'slug' program showed no
significant
difference in yields or foliar nutrient status between the two systems.
But this was excellent ground to begin with. Let's hear it , Folks!
Blake Sanden
Irrigation Management & Agronomy Farm Advisor, Kern County
1031 S Mt Vernon Ave
Bakersfield, CA 92307
805-868-6218
blsanden@ucdavis.edu
>Richard Mead wrote:
>>
>> What struck me however, was that the grower maintained 90 ppm of N in the
>> irrigation water throughout the season and did not taper or decrease that
N
>> level near the end of the vegetable crop season. This is contrary to what
>> I've always heard. The grower contends that N carry over in the soil at
the
>> end of the season was normal. Is it the nature of the crop (a vegetable)
>> that constant nutrient rates are better throughout the season than the
>> "peak, then level off " routine?
>>
>> I've tried to initiate fertigion dcussions before on Trickle-L but was
>> not successful. Maybe the particulars of this article could spark a few
>> comments....hmm? Am I off base?
>
>Hallo everybody,
>Good idea, here is my comment. To apply the same nitrogen rate
>throughout the season is just the easiest way to hand fertigation. Only
>the level in the fertilizer tank has to be checked, which can be done by
>everybody. To change fertilizer rates means a lot of work and
>controlling of the crops visual or with some methods to check plan/soil
>nutrition status in oder to reajust fertilizer rates if nessesary.
>Running with the same concentration has the philosophy that
>transpiration/water uptake of the plant is correlated with the growth
>rate. But this is only a general rule. In an early state of the crop the
>roots are poorly developed, so nutrient concentration should be as high
>as possible. (This is why recommendations for preplant fertilization
>rates are often as high as the total nutrient demand of the crop). If
>the crop is well established and root density is high, it should be
>possible to reduce the fertilizer concentration. - I have just checked
>Rick Snyder=B4s handbook on Greenhouse Tomatoes: In growbags the nutrient
>concentration has to be increased with crop development. This indicates
>that with high nutrient demand of the plants the uptake rate increases
>in correlation to transpiration rate.
>I have heard that - independent of growth state - the nutrient
>concentration should be increased with low transpiration demand and
>decreased with high transpiration demand to maintain a constant uptake
>of nutrients by the plants.
>I am doing some research on fertigation on tomatoes this year with
>several fertigation strategies. Last year I worked on a constant weekly
>nitrogen rate which were stopped 4 weeks before the crop was finished
>(in this period the growth rate is very limited anyway due to low
>temperatures). With high application rates the results were good with
>the constant weeekly rate but with low application rates it seemed that
>the supply was sufficient from transplanting (into the field) to some
>time prior harvesting and the last six weeks of the crop. The time in
>between, when fruit load where increased, the plants showed some
>nutrient deficiency.
>This can be different with other crops like cauliflower, which has
>highest nutrient demand in the last couple or so weeks. This usually
>results in a very high nitrogen carry over.
>But while we learn more about the actual nutrient demand of the specific
>crop drip irrigation will provide a chance to supply just the amount of
>nutrients the crop will need at the moment.
>As you might sense the more I am writing about fertigation the more
>confused I get.
>So it would be great if many of you tricklers would contribute your
>thoughts to fertigation.
> _____________________________________________________________
>| Jochen Eberhard * * |
>| SLFA Versuchsbetriebe ( \ / ) |
>| Queckbrunnerhof \ / |
>| Dannstadter Str. 91 --- |
>| 67105 Schifferstadt (o|o) |
>| Germany ( ~~~ ) |
>| ( ) |
>| Tel: 0049 - 6235 - 2672 ( ) |
>| Fax: - - 82741 ( ooO Ooo ) |
>| email: Jochen.Eberhard@t-online.de |
>|_____________________________________________________________|
Date: Thu, 24 Apr 1997 16:52:42 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: Economic irrigation application amounts ...
At the risk of displaying ignorance .....
We've seen a nice discussion on various values for K(x) etc. The
discussion has also mentioned crop water use, etc.
Now, let's get a little further into this subject. Is anyone aware
of data that provides expected yield versus irrigation application
depths for different crops? Of course, yields will increase until the
full crop water use requirement is satisfied, but in many cases this
highest water use may not be the most profitable irrigation level
(especially in areas where water costs are high).
This yield data could be expressed in percentages - as in what
percentage of the fully-irrigated yield could we expect when we
apply, say, 80% of the fully-irrigated water requirement? This could
then be applied to local yields.
Many industries are balancing input costs with projected returns
now to maximize their profit, and the agricultural community is right
there with them. Maybe a grower could do this, lower his yields by
5% or 10%, but increase his actual profit by 5% to 10%.
And, considering that the in-row or in-field distribution equipment
would largely be the same, we as irrigation professionals would only
need to modify pumping equipment and mailine / sub-main sizes to
compare the installation and operating costs of various application
rates.
Thanks in advance for your references and comments.
Bryan
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
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, 24 Apr 1997 16:08:25 -0500
From: Freddie Lamm <FLamm@OZNET.KSU.EDU>
Subject: Re: Economic irrigation application amounts ...
Bryan:
Yields vs irrigation amount are going to be highly dependant on the
climate and soils of the region in question. Even when you put it
into percentages, it would still be a problem. Ie. 80% of 6
inches might leave a tolerable 1.2 inch deficit, while 80% of 20
inches might leave a intolerable 4 inch deficit.
Yields vs irrigation amount is also subject to tremendous annual
variations, more so than yield vs ET.
However, we are doing some modeling research to see how on a
long-term basis corn yields are affected by irrigation system
capacity (gpm/acre or inches/day). Our modeling is using irrigation
scheduling to irrigate as needed IF not constrained by the irrigation
capacity. Our work is not really ready for prime time yet.
This type of work has been done before as per instance Terry Howell's
work on sprinkler capacity in the Southern High Plains.
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, 25 Apr 1997 08:32:01 -1000
From: Hugh Campbell <hcampbel@WEBFRONT.NET.AU>
Subject: change of e-mail address - Hugh Campbell
Hello list members,
Just a courtesy message advising I have signed off Irrigation-L and =
Trickle-L from Hugh_Campbell@msn.com and resubscribed under =
<hcampbel@webfront.net.au>. Any of you who may have my old address can =
you please change it? Note that new address has only one l in hcampbel.
Regards
Hugh Campbell
Narrandera
Australia
Date: Thu, 24 Apr 1997 17:08:48 -0700
From: "J.D. Oster" <oster@MAIL.UCR.EDU>
Subject: Economic irrigation
John Hanks in Utah and researchers in California studied the effects of
amount of applied water on crop yield. Experimentally determined yields for
several crops increased linearly with increasing amount of applied water
available to the crop. When the applied water is expressed as a fraction of
the potential crop ET for a given location, regional climatic conditions
are reduced. See Letey and Dinar 1986 (Simulated crop-production functions
for several crops when irrigated with saline waters. Hilgardia 54:1-32.)
for a good introduction to the literature and to how the information has
been applied for conditions of variable salinities in the irrigation water.
I believe these models do provide a way to estimate the economic impacts of
underirrigation. Check out an article in Agr. Water Management 25:271. 1994
for how the models were used to illustrate the impacts on crop yields and
drainage volume for alfalfa of underirrigation. Based on the cost of water,
the cost of drainage water disposal and the value of the crop, one should
be able to do the economic assessment also. See Knapp et al, 1990. Water
Res. Res. 26:1335 for example.
End of TRICKLE-L Digest - 23 Apr 1997 to 24 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sat Apr 26 01:05 EDT 1997
Date: Sat, 26 Apr 1997 00:02:55 -0600
Subject: TRICKLE-L Digest - 24 Apr 1997 to 25 Apr 1997
There are 4 messages totalling 188 lines in this issue.
Topics of the day:
1. (Fwd) Re: Economic irrigation - reply
2. Economics of Production vs. Resource application
3. Economic irrigation
4. Soil conditioner
Date: Fri, 25 Apr 1997 09:05:12 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: (Fwd) Re: Economic irrigation - reply
------- Forwarded Message Follows -------
Date: Thu, 24 Apr 1997 21:41:20 -0700 (PDT)
To: wsmth@CLEMSON.EDU
From: Ken Shackel <kashackel@ucdavis.edu>
Subject: Re: Economic irrigation application amounts ...
Bryan,
At 04:52 PM 4/24/97 -0500, you wrote:
> Now, let's get a little further into this subject. Is anyone aware
>of data that provides expected yield versus irrigation application
>depths for different crops? Of course, yields will increase until the
>full crop water use requirement is satisfied, but in many cases this
>highest water use may not be the most profitable irrigation level
>(especially in areas where water costs are high).
Very relevant questions here, in fact, one of the reasons I brought up the
K(x) issue was because Dave Goldhamer suggested to me once that what we
really need to come up with is a K sub ($). We have been looking at
potential benefits of water stress in prune trees, because a 3 year study
indicated that mild water stress could have economically beneficial effects
in prune (Lampinen et.al., 1995, J.Amer.Soc.Hort.Sci. 120:139-147), partly
by increasing flowering and partly by reducing fruit fresh weight without
reducing fruit dry weight. Anyway, over the last few years we have been
getting away with applying about 60% of the calculated orchard ET, with no
detectable effect on productivity (although not the increase in productivity
we were thinking we would get). On the way, we also found out that many
prune orchards in production over the state exhibit a moderate level of tree
water stress, so it may be that growers already have a feel for the benefits
of regulated deficit irrigation, or at least a feel for the diminishing
returns from "full irrigation". Tree crops, particularly something like
prune, might be unique in this respect, but I suspect that a moderate amount
of water stress, even if it reduces overall plant water use, may have
beneficial side effects, depending on the crop (eg., cotton). Of course,
this goes against the positive association of biomass production and yield
with canopy water use, but I think that generality might need a bit of fine
tuning.
Ken Shackel
Department of Pomology
University of California
Davis, CA 95616-8683
[note: new area code (530) as of November 1, 1997]
Phone (916) 752-0928
Fax (916) 752-8502
Date: Fri, 25 Apr 1997 09:50:00 -0700
From: "Thurston, Anna" <athursto@CI.TACOMA.WA.US>
Subject: Economics of Production vs. Resource application
This analysis appears to be heading towards the incorporation of resources
and processes other than but as important as the proper application of
water. I am NOT an expert on this, but I can't ignore what I've seen Nature
do and hope that the following comments are relevant and/or inspirational:
In my experience, no plant (whether a house plant, fruit/vegetable or
landscape specimen) grows well under water applications that create field
capacity. This makes sense to me because there is likely to be less oxygen
in the soil for biological and uptake activities of soil organisms and
roothairs, respectively.
I am also starting to wonder about the effect of organic matter as it
relates to water holding capacity and availability, soil microbial activity,
and ultimately increased plant production. I have seen significant
differences in plant responses and general soil health between sites where
no OM (organic matter) was applied after all surface growth had been
removed, where OM was incorporated into the soil to a depth of 6-8 inches,
and where it was purposefully allowed to accumulate on the soil surface and
infiltrate over time (years) .
Where I have made no attempt to enhance the soil with OM, I get an obviously
poor plant response, regardless of how much water I apply, even if I apply
chemical fertilizers. While the plant s may send up succulent growth, they
are simply less hardy and/or incapable of withstanding any extended dry
spell, high temperatures or damage from insects and disease (which they seem
to attract more of) and other environmental factors like wind and sun scald.
As a horticulturalist and landscaper specializing in water-efficient
installations, I have been taught to incorporate OM into the soil. This is
useful for new lawn installations (esp. sodded vs. seeded), but seemingly
impossible for already existing sites. The same recommendations are provided
to gardeners, only emphasizing that well-composted OM is used over fresh or
"hot" sources like manures. This generally provides good results, but unless
I mulch the soil surface I loose a lot of water to exposed soil between
establishing plants, and have to deal with an explosion of germinating weeds
(provided I am also trying to reduce my use of pre-emergent herbicides and
other chemical input).
In other applications I have experimented with the seeding of grasses and
perennials, planting of vegetables and the installation of ornamentals in
areas that have not been tilled, but have been sprayed with herbicide and
treated with 2-4" of OM. Where I have been able to leave the soil alone
under a layer of OM the plants (including vegetables) have usually
outperformed either of the other treatments, but only if I watered according
to the plant's and soil's need.
My point/theory is that all of these factors are so inter-connected that to
only look at one is to miss the bigger picture. Not only would it be great
to have such a formula that statistically calculates crop coefficients to
yield as you all have been discussing, but I wonder if it needs to
incorporate an OM factor too.
Date: Fri, 25 Apr 1997 10:47:00 -0700
From: "Thurston, Anna" <athursto@CI.TACOMA.WA.US>
Subject: Re: Economic irrigation
This analysis appears to be heading towards the incorporation of resources
and processes other than but as important as the proper application of
water. I am NOT an expert on this, but I can't ignore what I've seen Nature
do and hope that the following comments are relevant and/or inspirational:
In my experience, no plant (whether a house plant, fruit/vegetable or
landscape specimen) grows well under water applications that create field
capacity. This makes sense to me because there is likely to be less oxygen
in the soil for biological and uptake activities of soil organisms and
roothairs, respectively.
I am also starting to wonder about the effect of organic matter as it
relates to water holding capacity and availability, soil microbial activity,
and ultimately increased plant production. I have seen significant
differences in plant responses and general soil health between sites where
no OM (organic matter) was applied after all surface growth had been
removed, where OM was incorporated into the soil to a depth of 6-8 inches,
and where it was purposefully allowed to accumulate on the soil surface and
infiltrate over time (years) .
Where I have made no attempt to enhance the soil with OM, I get an obviously
poor plant response, regardless of how much water I apply, even if I apply
chemical fertilizers. While the plant s may send up succulent growth, they
are simply less hardy and/or incapable of withstanding any extended dry
spell, high temperatures or damage from insects and disease (which they seem
to attract more of) and other environmental factors like wind and sun scald.
As a horticulturalist and landscaper specializing in water-efficient
installations, I have been taught to incorporate OM into the soil. This is
useful for new lawn installations (esp. sodded vs. seeded), but seemingly
impossible for already existing sites. The same recommendations are provided
to gardeners, only emphasizing that well-composted OM is used over fresh or
"hot" sources like manures. This generally provides good results, but unless
I mulch the soil surface I loose a lot of water to exposed soil between
establishing plants, and have to deal with an explosion of germinating weeds
(provided I am also trying to reduce my use of pre-emergent herbicides and
other chemical input).
In other applications I have experimented with the seeding of grasses and
perennials, planting of vegetables and the installation of ornamentals in
areas that have not been tilled, but have been sprayed with herbicide and
treated with 2-4" of OM. Where I have been able to leave the soil alone
under a layer of OM the plants (including vegetables) have usually
outperformed either of the other treatments, but only if I watered according
to the plant's and soil's need.
My point/theory is that all of these factors are so inter-connected that to
only look at one is to miss the bigger picture. Not only would it be great
to have such a formula that statistically calculates crop coefficients to
yield as you all have been discussing, but I wonder if it needs to
incorporate an OM factor too.
Anna Thurston, Water Conservation Specialist
Tacoma Public Utilities
athursto@ci.tacoma.wa.us
(206)502-8723
Date: Fri, 25 Apr 1997 13:42:29 -0700
From: Robert Carian <grapegrower@EARTHLINK.NET>
Subject: Soil conditioner
has anyone ever used, or heard of being used "beet Lime" as an soil
additive. I see it being used here in the coachella valley, banded on
top of the soil, under the emitters.
Thanks in advance.
R. Carian
End of TRICKLE-L Digest - 24 Apr 1997 to 25 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Sun Apr 27 01:03 EDT 1997
Date: Sun, 27 Apr 1997 00:01:35 -0600
Subject: TRICKLE-L Digest - 25 Apr 1997 to 26 Apr 1997
There are 3 messages totalling 99 lines in this issue.
Topics of the day:
1. Micronutrients and drip
2. Fertigation - fertilizer sources
3. Fertigation - organic fertilizer sources
Date: Sat, 26 Apr 1997 08:32:55 -0700
From: Richard Mead <rmead@CYBERGATE.COM>
Subject: Re: Micronutrients and drip
Blake,
Many thanks to you and Jochen for responding to my initial fertigation
posting.
Going back to your question >In terms of uptake efficiency on a pound for
pound applied basis, are P, Fe, Cu, and Zn more available when applied to a
saturated zone under a drip emitter or in non-saturated conditions as with
microsprinklers?<
This all depends on soil conditions (compacted, well drained, water logged
etc.) and/or management of the microirrigation system. Are there actual
roots near the saturated zone under an emitter (SDI situation)?
The philosophy behind high frequency irrigation is based on the assumption
that there is no root growth x cm away from the emitter opening. [This
debate could go off on a tangent due to differences of opinion about
emitter clogging.] However, let's assume that it is saturated near the drip
emitter and roots are within this zone. If O2 levels are low enough in the
zone, possible anaerobic metabolic end products may be created by the roots
that could be toxic to the plant. If the O2 level is optimal, root exudates
could influence the availability of Fe, Cu and Zn. It would be interesting
to see research on soil moisture levels vs P, Fe, Cu and Zn uptake, yet I
would assume soil moisture levels which are optimal for transpiration
should be optimal for nutrient uptake. Am I making too big of an assumption?
Regarding: >Is a high concentration 'slug' 3 to 4 times a year advantageous
(tree crops for example) when using phosphoric acid or low continuous
dosage the way to go.<
P is a unique element in that it is so highly bound. The P in the soil
solution can be 1000 fold lower than the absorbed soil P. When P is
absorbed by the root at a high rate, the soil solution in the direct root
vicinity is depleted of P. This depletion creates a gradient between P at
the root surface and P in the soil. This concentration gradient regulates
the rate of P diffusion toward the plant root. Who knows what the optimal
moisture status is in a drip system or microspray system for this
diffusion? Yet the rate of P delivery from a fertigation system probably is
more important than moistures fluctuations in the soil. I contend that
constant P levels (low dosage) would help maintain the P gradient at
constant levels and could accommodate strange swings in the weather
(variable ET rates) through out the season. If the P delivery is tied to a
biofeedback system(constant rate)rather than a calendar approach (slug),
optimal P uptake is ensured.
Finally regarding your comment > What about the 'humic acid craze'?<
Please expand on the 'humic acid craze'. My understanding of humic acid is
that its cation exchange capacity is very high and divalent cations are
preferentially absorbed vs. monovalent cations. What advantage does this
give a crop, other than possibly help leach Na? How is the humic acid applied?
Richard Mead
Trickle-L owner/manager
Date: Sat, 26 Apr 1997 12:29:58 -0008
From: Larry Selman <lselman@GOT.NET>
Subject: Fertigation - fertilizer sources
I am new to the list an would like to find sources of organic
fertilizers suitable for fertigation ie. fish, kelp etc.
Any help would be appreciated.
Larry Selman
-------------------------
| lselman@got.net |
| http://www.selman.com |
| 1-800 538-0766 |
-------------------------
Date: Sat, 26 Apr 1997 12:49:15 -0008
From: Larry Selman <lselman@GOT.NET>
Subject: Fertigation - organic fertilizer sources
I am new to the list an would like to find sources of soluble organic
fertilizers suitable for fertigation ie. fish, kelp etc.
Any help would be appreciated.
Larry Selman
-------------------------
| lselman@got.net |
| http://www.selman.com |
| 1-800 538-0766 |
-------------------------
End of TRICKLE-L Digest - 25 Apr 1997 to 26 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Mon Apr 28 01:02 EDT 1997
Date: Mon, 28 Apr 1997 00:00:12 -0600
Subject: TRICKLE-L Digest - 26 Apr 1997 to 27 Apr 1997
There are 5 messages totalling 114 lines in this issue.
Topics of the day:
1. Brand new to all of this
2. soil amendment question
3. Fertigation in blueberries
4. soil admendments re: beet lime
5. Looking for posiiton in Irrigation Industry
Date: Sun, 27 Apr 1997 01:32:56 -0400
From: "Kym Zorn." <Kymzorn@AOL.COM>
Subject: Brand new to all of this
Hello!
I am new to this and would welcome any input. I have an 800 sq ft garden in
the notoriously humid Ohio Valley . This is my second growing season and I'm
trying to undue years of neglect of the soil.It is very important to me that
1)I improve the
soil and 2)I figure out a way deliver nutrients every time I water.Looking at
various drip irrigation systems but don't know enough about any of it.Any
help at all is greatly appreciated.Thanks much.
Kym Zorn
419 Pine Street
Louisville,KY 40204
kymzorn@aol.com
Date: Sun, 27 Apr 1997 02:39:47 -0600
From: Goldberg <goldberg@EDEN.COM>
Subject: soil amendment question
Can anyone recommend a soil amendment/coating which will restrict the
movement of water in a very loose sandy/silty (imported) topsoil?
Rapid surfacing/chimneying in a drip irrigated wastewater drainfield might
be
prevented by the addition of an amendment which would fill pore spaces,
give structure, and otherwise inhibit the upward movement of water in soil
with
very little structure. Thanks for the help.
Rick Goldberg
Drip-Tech Wastewater Systems
Date: Sun, 27 Apr 1997 08:42:27 -0500
From: Don Pitts <djp@ICON.IMOK.UFL.EDU>
Subject: Re: Fertigation in blueberries
Marybeth,
Please send your request to Dr. Tom Obreza at E-mail
taob@icon.imok.ufl.edu. Tom is our soil fertility scientist and is working
extensively with blueberries.
Regards,
Don Pitts
At 11:21 AM 4/23/97 -0400, you wrote:
>I'm looking for fertigation recommendations for 2 year old blueberries. A
>drip system will be installed this spring using 1 gph emitters 24" spacing.
>Design pressure is 45psi at PRV and flow rate for zone is 300gpm. The grower
>requested recommendations on the type of fertilizer to apply, the rate of
>application, fertilizer injection schedule, chemigation for weeds, nematodes,
>ants etc. Also any info on liming through the system to raise pH from 3.8 to
>4.8. There have been problems with very low pH soils on some blueberry fields
>but not associated with drip irrigation. If there is any experiences, advice,
>and recommendations that can be passed on to NJ blueberry growers, it would
>be very helpful.
>
>MaryBeth Sorrentino
>Water Management Specialist
>USDA, Natural Resources Conservation Service
>New Jersey
>
Date: Sun, 27 Apr 1997 08:52:08 -0700
From: Robert Carian <grapegrower@EARTHLINK.NET>
Subject: soil admendments re: beet lime
has anyone ever used, or heard of being used "beet Lime" as an soil
additive. I see it being used here in the coachella valley, banded on
top of the soil, under the emitters.
Thanks in advance.
should this be a duplicate posting, my apoligies.
Date: Sun, 27 Apr 1997 15:09:50 -0400
From: Elaine Marans <Em5887@AOL.COM>
Subject: Looking for posiiton in Irrigation Industry
I am an irrigation industry professional, looking for a position.
My background includes managing subtropical orchards and irrigation systems.
Recently I have worked for irrigation manufacturers in Southern California.
I have held research oriented positions in several fields.
My education includes a certificate in Subtropical Orchard management from
Ruppin Institute in Israel, as well as a BSME from the University of
Toronto. I am currently pursuing a certificate in Marketing and Sales at
UCLA.
If anyone has any leads on positions available in our industry, please
contact me at
Em5887@aol.com
Thank you
Elaine Marans
End of TRICKLE-L Digest - 26 Apr 1997 to 27 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Tue Apr 29 01:04 EDT 1997
Date: Tue, 29 Apr 1997 00:03:16 -0600
Subject: TRICKLE-L Digest - 27 Apr 1997 to 28 Apr 1997
There are 3 messages totalling 118 lines in this issue.
Topics of the day:
1. soil amendment question
2. soil admendments re: beet lime
3. Micronutrients and drip
Date: Mon, 28 Apr 1997 08:40:56 -0700
From: "J.D. Oster" <oster@MAIL.UCR.EDU>
Subject: Re: soil amendment question
Rick: water quality may be part of the problem. What is the electrical
conductivity and sodium adsorption ratio of the water? If the combination
of these two values is not correct, the water may be causing aggregate
failure and particle dispersion, resulting in a 'chimney" above the buried
emitter. the develoAt 02:39 AM 4/27/97 -0600, you wrote:
>Can anyone recommend a soil amendment/coating which will restrict the
>movement of water in a very loose sandy/silty (imported) topsoil?
>
>Rapid surfacing/chimneying in a drip irrigated wastewater drainfield might
>be
>prevented by the addition of an amendment which would fill pore spaces,
>give structure, and otherwise inhibit the upward movement of water in soil
>with
>very little structure. Thanks for the help.
>
>Rick Goldberg
>Drip-Tech Wastewater Systems
>
Date: Mon, 28 Apr 1997 08:47:12 -0700
From: "J.D. Oster" <oster@MAIL.UCR.EDU>
Subject: Re: soil admendments re: beet lime
Adding lime to a soil that contains lime, which is also irrigated with
Colorado River water -- a 'saturated' lime solution, is a bit like taking
coal to Newcastle. However, there may be circumstances where it could help.
If the soil has become acidic due to fertilizer application, it would raise
the soil pH. If beet lime contains N, or P, or K, it would have a
nutritional value. Finally, adding lime to lime shouldn't do any harm. At
08:52 AM 4/27/97 -0700, you wrote:
>has anyone ever used, or heard of being used "beet Lime" as an soil
>additive. I see it being used here in the coachella valley, banded on
>top of the soil, under the emitters.
>Thanks in advance.
>should this be a duplicate posting, my apoligies.
>
Date: Mon, 28 Apr 1997 18:24:14 +0000
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Re: Micronutrients and drip
Richard and the other Tricklers,
My concern is not only availability at a given soil moisture but transient
or highly localized impacts of micro acidification that might be achieved
by "slugs" of phos acid and consequent uptake of P, Fe, Cu and Zn in say
the presence of free lime and a soil pH of 7.8. Many growers with buried
tape have adopted a phos acid "slug" philosophy as a mechanism to
periodically burn roots back from emission points and prevent root
intrusion. What's the verdict, folks?
By "humic acid craze" I was refering to leonardite (spelling?) extractions
and by products that some of the fertilizer companies have been adding to
their liquid complex fertilizers as a means to boost "root productivity".
Growers using the product are probably paying $15 to $30 extra for this
'boost' in high value crops; with the thought that the stuff is good
insurance. I have as yet to see compelling results from any replicated
trials.
Blake Sanden
Irrigation Management & Agronomy Farm Advisor, Kern County
1031 S Mt Vernon Ave
Bakersfield, CA 92307
805-868-6218
blsanden@ucdavis.edu
ON 4/26 RICHARD MEAD WROTE:
>It would be interesting
>to see research on soil moisture levels vs P, Fe, Cu and Zn uptake, yet I
>would assume soil moisture levels which are optimal for transpiration
>should be optimal for nutrient uptake. Am I making too big of an assumption?
>
>Regarding: >Is a high concentration 'slug' 3 to 4 times a year advantageous
>(tree crops for example) when using phosphoric acid or low continuous
>dosage the way to go.<
>
>P is a unique element in that it is so highly bound. The P in the soil
>solution can be 1000 fold lower than the absorbed soil P. When P is
>absorbed by the root at a high rate, the soil solution in the direct root
>vicinity is depleted of P. This depletion creates a gradient between P at
>the root surface and P in the soil. This concentration gradient regulates
>the rate of P diffusion toward the plant root. Who knows what the optimal
>moisture status is in a drip system or microspray system for this
>diffusion? Yet the rate of P delivery from a fertigation system probably is
>more important than moistures fluctuations in the soil. I contend that
>constant P levels (low dosage) would help maintain the P gradient at
>constant levels and could accommodate strange swings in the weather
>(variable ET rates) through out the season. If the P delivery is tied to a
>biofeedback system(constant rate)rather than a calendar approach (slug),
>optimal P uptake is ensured.
>
>Finally regarding your comment > Whatout the 'humic acid craze'?<
>
>Please expand on the 'humic acid craze'. My understanding of humic acid is
>that its cation exchange capacity is very high and divalent cations are
>preferentially absorbed vs. monovalent cations. What advantage does this
>give a crop, other than possibly help leach Na? How is the humic acid applied?
>
>Richard Mead
>Trickle-L owner/manager
End of TRICKLE-L Digest - 27 Apr 1997 to 28 Apr 1997
****************************************************
>From owner-TRICKLE-L@crcvms.unl.edu Wed Apr 30 01:07 EDT 1997
Date: Wed, 30 Apr 1997 00:06:01 -0600
Subject: TRICKLE-L Digest - 28 Apr 1997 to 29 Apr 1997
There are 3 messages totalling 127 lines in this issue.
Topics of the day:
1. Lowering water pH by burning Sulphur???
2. Fertigation fads
3. Micronutrients and drip
Date: Tue, 29 Apr 1997 11:31:03 -0500
From: "W. Bryan Smith" <wsmth@CLEMSON.EDU>
Subject: Lowering water pH by burning Sulphur???
Posted to Trickle-L and Irrigation-L - sorry if you received two
copies!
--------------------------------------------
I just had a call from a grower who needs to lower his irrigation
water pH. He is considering two methods - direct injection of acid
and burning sulphur.
I am not familiar with the second method. Apparently, the sulphur
is burned, with the subsequent gas injected in the irrigation line.
The client claims many benefits from this practice besides lowering
water pH and says the practice is used on golf courses regularly.
It does have a pretty hefty inital cost.
Can anyone provide some information on this method - and pros and
cons concerning it?
Thanks!
Bryan
=|===|===|===|===|===|===|===|===|===|===|=
W. Bryan Smith
Area Extension Agent - Irrigation / Water Quality
Clemson Extension Service
P.O. Box 160
Newberry, South Carolina 29108 USA
Office: 803 276-1091 FAX: 803 276-1095
Internet: wsmth@clemson.edu
=|===|===|===|===|===|===|===|===|===|===|=
All opinions are my own and not reflective of the
policies of Clemson University or the Cooperative
Extension Service.
Date: Tue, 29 Apr 1997 11:02:21 +0000
From: Blake Sanden <blsanden@UCDAVIS.EDU>
Subject: Fertigation fads
Richard and the other Tricklers,
My concern is not only availability at a given soil moisture but transient
or highly localized impacts of micro acidification that might be achieved
by "slugs" of phos acid and consequent uptake of P, Fe, Cu and Zn in say
the presence of free lime and a soil pH of 7.8. Many growers with buried
tape have adopted a phos acid "slug" philosophy as a mechanism to
periodically burn roots back from emission points and prevent root
intrusion. What's the verdict, folks?
By "humic acid craze" I was refering to leonardite (spelling?) extractions
and by products that some of the fertilizer companies have been adding to
their liquid complex fertilizers as a means to boost "root productivity".
Growers using the product are probably paying $15 to $30 extra for this
'boost' in high value crops; with the thought that the stuff is good
insurance. I have as yet to see compelling results from any replicated
trials.
Blake Sanden
Irrigation Management & Agronomy Farm Advisor, Kern County
1031 S Mt Vernon Ave
Bakersfield, CA 92307
805-868-6218
blsanden@ucdavis.edu
ON 4/26 RICHARD MEAD WROTE:
>It would be interesting
>to see research on soil moisture levels vs P, Fe, Cu and Zn uptake, yet I
>would assume soil moisture levels which are optimal for transpiration
>should be optimal for nutrient uptake. Am I making too big of an assumption?
>
>Regarding: >Is a high concentration 'slug' 3 to 4 times a year advantageous
>(tree crops for example) when using phosphoric acid or low continuous
>dosage the way to go.<
>
>P is a unique element in that it is so highly bound. The P in the soil
>solution can be 1000 fold lower than the absorbed soil P. When P is
>absorbed by the root at a high rate, the soil solution in the direct root
>vicinity is depleted of P. This depletion creates a gradient between P at
>the root surface and P in the soil. This concentration gradient regulates
>the rate of P diffusion toward the plant root. Who knows what the optimal
>moisture status in a drip system or microspray system for this
>diffusion? Yet the rate of P delivery from a fertigation system probably is
>more important than moistures fluctuations in the soil. I contend that
>constant P levels (low dosage) would help maintain the P gradient at
>constant levels and could accommodate strange swings in the weather
>(variable ET rates) through out the season. If the P delivery is tied to a
>biofeedback system(constant rate)rather than a calendar approach (slug),
>optimal P uptake is ensured.
>
>Finally regarding your comment > Whatout the 'humic acid craze'?<
>
>Please expand on the 'humic acid craze'. My understanding of humic acid is
>that its cation exchange capacity is very high and divalent cations are
>preferentially absorbed vs. monovalent cations. What advantage does this
>give a crop, other than possibly help leach Na? How is the humic acid applied?
>
>Richard Mead
>Trickle-L owner/manager
Date: Tue, 29 Apr 1997 13:40:04 -0700
From: Robert Carian <grapegrower@EARTHLINK.NET>
Subject: Re: Micronutrients and drip
>Please expand on the 'humic acid craze'. My understanding of humic acid is
>that its cation exchange capacity is very high and divalent cations are
>preferentially absorbed vs. monovalent cations. What advantage does this
>give a crop, other than possibly help leach Na? How is the humic acid
>applied?
I have been using low doses of humic acid this season on a perlette
vineyard that has very high na levels and the growth has been far more
normal than past seasons. It has been a cheap temporary fix until I can
leach the soil with sprinklers in the fall.
End of TRICKLE-L Digest - 28 Apr 1997 to 29 Apr 1997
****************************************************
Prepared by Steve Modena, AB4EL
Suggestions and comments to: modena@SunSITE.unc.edu