AGMODELS-L: 199710XX
is the compilation of discussion during Oct 97
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Date: Wed, 01 Oct 1997 00:03:24 -0600
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There are 3 messages totalling 280 lines in this issue.
Topics of the day:
1. The history of ag modeling.
2. The history of ag modeling... Thank you John.
3. Key developments
Date: Tue, 30 Sep 1997 14:36:07 -0500
From: "E. John Sadler" (sadler@SUNBRN.FLORENCE.ARS.USDA.GOV)
Subject: The history of ag modeling.
Greetings,
After the quick note the other day about historical references in ag
modeling, I read over the dissertation again and concluded that
several events and lines of work merited expansion beyond the
paragraph in the earlier e-mail. The following is the particular
section of the dissertation, re-scanned today (I couldn't find the
old CP/M disks!). It is about 10k long. The references are about 33k
long, and I can only send them as an attachment. Therefore, I will
send them only to those who request it.
EJ Sadler 1983. Simulation of the energy, carbon, and water balance
of a fluid-roof greenhouse. Texas A&M University, PhD Dissertation,
pg 18-24.
Crop Models
There are many models of crop growth, ranging from the fairly simple
to the extremely complex. Unfortunately, there is a scarcity of
reviews of the subject in recent years. The review of Loomis and
Williams (1969), and the collection of papers from the International
Biological Programme (IBP/PP) technical meeting in Trebon,
Czechoslovakia, in 1969, provided a comprehensive view of the
discipline at that time. A brief review by Hesketh and Jones (1976)
covers the modeling of cotton. Thornley (1976) covered the subject
of modeling and reviewed some models in his book. Hildreth (1976)
covered several of the better-known crop models.
To organize the existing models for a logical discussion, the
classification of Hildreth (1976) was adopted: a) plant function
models, b) crop growth and yield models, and c) crop development and
yield models. If physical principles are simulated throughout, the
degree of complexity generally increases from a) to c). The plant
function models concern instantaneous processes. The crop growth and
yield models integrate the plant function models at the plant or
plant community scale over short time periods. The development
models extend the growth models over the growing season, including
simulation of physiological events such as flowering and maturity.
There do exist crop growth and crop development models that start
with empirical observations and that are more simple than the
integrated process type.
Simulation objectives of the plant function models include radiation
interception, photosynthesis rate, respiration rate, translocation or
carbohydrate partitioning, leaf energy balance, transpiration rate,
and root water uptake. An extensive review of light interception
models was given by Lemeur and Blad (1974). Since then, analyses
have been made by Sinclair and Lemon (1974), Anderson and Miller
(1974), Norman and Jarvis (1974, 1975), Mann et al. (1977), Kimes et
al. (1980), Denholm (1981a, 1981b), Oker-Blom and Kellomaki (1982),
and Sinclair and Knoerr (1982). Models of photosynthesis have been
reported by Chartier (1970), Lommen et al. (1971), Van Bavel (1975),
Tenhunen et al. (1976a, 1976b), Enoch and Sacks (1978), and Thornley
et al. (1981), with a review by Thornley (1976). Respiration has
been modeled by McCree (1970, 1974), Penning de Vries (1972, 1974,
1975), Penning de Vries et al. (1974), Thornley (1976, 1977), Gay
(1981), Thornley et al. (1981), and others. For a review and
analysis, see Gay (1981). Leaf energy balance was simulated by
Gates (1968) and Van Bavel et al. (1973), among others. Models of
crop evapotranspiration abound. Thornthwaite (1948), Penman (1948),
Blaney and Criddle (1962), Jensen and Haise (1963), Monteith
(1965a), and Van Bavel (1966) are examples. A comprehensive
comparison of water use models was made for a volume edited by Jensen
(1973). Much work has been done on root water uptake, with Lascano
(1982) giving an extensive, recent review.
In the third category, there exist two major classifications of
models, based on the method of simulation. The first is the multiple
regression or other statistical method of empirical modeling of crop
yield, development, or status, based on environmental variables,
usually temperature and rainfall. These will not be further
discussed. The second integrates the plant functions in some manner,
summing the individual effects to result in growth or yield.
A historical perspective of the evolution of crop simulation models
is useful. One of the earlier works was by Monsi and Saeki (1953)
and Kasanaga and Monsi (1954), who studied the importance of light in
dry matter production, and introduced the idea of dividing the
canopy into layers. Monteith (1965b), De Wit (1965) and Duncan et
al. (1967) reported models of photosynthesis that were based on
interception of radiation only, and not on temperature or CO2
concentration. Stewart and Lemon (1969) used the light interception
models of Duncan et al. (1967) and De Wit (1965) in the
Soil-Plant-Atmosphere Model (SPAM), which considered the microclimate
in each layer of a canopy.
The work cited above was known at the time of the IBP/PP technical
meeting in Trebon, Czechoslovakia. In that meeting, several papers
of note were given. De Wit et al. (1970) described the Elementary
Crop Simulator ELCROS. Ross (1970), Anderson (1970), and Kuroiwa
(1970) reviewed light interception and photosynthesis models. Acock
et al. (1970) discussed spatial variability of light in the canopy.
Tooming (1970) discussed net photosynthesis and plant adaptation.
Monsi and Murata (1970) discussed dry matter distribution in crops.
Denmead (1970) and Uchijima (1970) both discussed simulations of
transfer processes within canopies. Also, the paper of McCree
(1970), listed earlier, was given.
After the Trebon meeting, the work started in the Netherlands by De
Wit (1965) and De Wit et al. (1970) continued. Goudriaan and
Waggoner (1972) described an early version of a model updated and
described fully by Goudriaan (1977), and tested by Stigter et al.
(1977). The model BACROS, for Basic Crop Simulator, evolved (De Wit
et al., 1978). A third model simulated field water use and crop
yield (Feddes et al., 1978).
In the United States, Chen et al. (1969) started work that evolved
into the Nebraska corn model (Splinter, 1973; Splinter, 1974; Childs
et al., 1977). A group in Arizona developed a cotton model
(Stapleton and Meyers, 1971; Stapleton et al., 1973). In Ohio,
Curry (1971) and Curry and Chen (1971) described a dynamic model of
plant growth, and Curry et al. (1975) described the soybean growth
model SOYMOD I, which was used by Meyer et al. (1981) to simulate
reproductive processes and senescence. At Purdue University in
Indiana, Miles et al. (1973) and Holt et.al. (1975) developed a model
of alfalfa, SIMED. In Texas, Arkin et al. (1976) and Maas and Arkin
(1978) described a simulation model of grain sorghum, SORGF.
Other models developed in the 1970's include the CORNMOD model of
Baker and Horrocks (1974), the model of Phragmites communis reported
by Ondok and Gloser (1978a, 1978b), the barley model of Kallis and
Tooming (1974), the shortgrass prairie model of Conner et al. (1974),
the wheat model of Milthorpe and Moorby (1974), the tobacco model of
Wann et al. (1978), and corn model of Russo and Knapp (1976).
The descendants of the Duncan et al. (1967) model will now be
examined. Three partial tests of their model were reported (Loomis
et al., 1968; Williams et al., 1968; and Loomis and Williams, 1969),
and an independent test was reported by Keener (1972) and Keener and
McCree (1975). Duncan (1971) studied crop architecture and its
influence on canopy photosynthesis using the 1967 model, and included
a CO2 transport routine to study the vertical profiles of CO2 within
a canopy (Duncan and Barfield, 1970, 1971). Duncan also
collaborated with the group at Mississippi State University to create
SIMCOT and related models of cotton (Hesketh et al., 1971, 1972;
Baker et al., 1972). The SIMCOT model series was further documented
by Jones et al. (1974), and McKinion et al. (1975), who included the
nitrogen balance of the cotton crop. Duncan's coauthors in the 1967
paper developed a model of sugar beet growth, SUBGOL (Fick et al.,
1975; Loomis and Ng, 1977; Hunt and Loomis, 1979).
Meanwhile, SPAM (Stewart and Lemon, 1969). itself partially based on
the 1967 model and also De Wit (1965), was generating excitement in
modeling. The initial journal article (Lemon et al., 1971) showed
many researchers the potential for modeling the microclimate within
crops. Lemon et al. (1973) studied evapotranspiration with SPAM.
Shawcroft et al. (1974) described SPAM and a sensitivity analysis.
Van Bavel (1974) used part of SPAM and the leaf action model of Van
Bavel et al. (1973) to create CANLAM and study the behavior of
sunflowers with respect to soil water potential. This combination
of SPAM and the leaf action model was used in an optimization study
of water use efficiency (Ahmed, 1974; Ahmed et al., 1976). The CO2
assimilation equations of Van Bavel (1975) were incorporated into
their model, then named CANLAM2. This was used in simulations of the
efficiency of field CO2 enrichment by Takami (1974) and Takami and
Van Bavel (1975), and in investigations of the effect of respiration
on crop production by McCree and Van Bavel (1977). Takami and
Kumashiro (1982) used CANLAM2 to study the effect of canopy
architecture on rice photosynthesis. In unrelated work, Sinclair et
al. (1977) compared the original SPAM, a simplified version of SPAM,
and a "big leaf" model similar to that of Monteith (1965b).
Conclusion of Literature Review
For the purpose of satisfying the objectives of this thesis, the SG79
greenhouse energy balance model of Van Bavel and Sadler (1979b), and
the CANLAM2 model of Takami and Van Bavel (1975) and of McCree and
Van Bavel (1977) were selected. The choice of SG79 was simple: it
was the only model that considered the energy, water, and CO2 balance
of the greenhouse together. Of the crop models, the CANLAM2 model
was chosen, in spite of its complexity relative to SG79, because the
inputs and outputs were compatible with those in SG79's crop
calculation section. In addition, the modification of the code,
which was in machine storage here, was more simple than either
obtaining another model and modifying it, entering a model from a
listing, or building one from the start.
==============================================================
E. John Sadler, Ph.D.
USDA-ARS sadler@florence.ars.usda.gov
Coastal Plains Soil, Water,
and Plant Research Center 803-669-5203x112 (voice)
2611 West Lucas St. 803-669-6970 (fax)
Florence, SC 29501-1241
U.S.A.
==============================================================
Date: Tue, 30 Sep 1997 14:39:31 -0500
From: "Robert M. Caldwell" (serc018@UNLVM.UNL.EDU)
Subject: Re: The history of ag modeling... Thank you John.
Dear John Sadler, and other list members,
Thank you for sending the literature review on early model development.
You have referenced some great literature.
Anyone have opinions on the key technology developments that helped
drive those early modeling activities? The availability of CSMP on IBM
mainframes is one, given the importance of the language to the early
research. What were some others?
Note also the importance of the International Biological Programme
(IBP). Any other projects or groups that should be mentioned?
Sincerely,
Bob Caldwell, Cropping Systems Specialist, Dept. of Agronomy/SEREC/NEREC
University of Nebraska - Lincoln
204 Mussehl Hall, P.O. Box 830714, Lincoln, NE 68583-0714
serc018@unlvm.unl.edu Phone: (402) 472-3674. FAX: (402) 472-3858.
Date: Tue, 30 Sep 1997 16:28:30 -0500
From: "E. John Sadler" (sadler@SUNBRN.FLORENCE.ARS.USDA.GOV)
Subject: Key developments
Greetings to the list,
Key developments should certainly include CSMP, as a lot of the
early 70's work used it, especially de Wit's group at Wageningen.
The PUDOC publication lists are very useful, as are several
dissertations published there. Developments in the 80's would be
the migration of simulations from mainframes to PCs. A simulation
now can be done faster than the CPU time usage on the 1980-vintage
mainframe, to say less of the clock-on-the-wall time. The majority
of the earlier models were in FORTRAN or CSMP; what are the current
versions written in? Most distributed software is compiled for the
PC, so development software is not such a big issue, which may be
important enough to mention. Integration into specialized
database managers such as decision support systems, GIS, and others
(Cite Caldwell's symposium at ASA this year) is becoming important.
The groups working in the 70's should include Duncan's, Lemon's,
Stapleton's, Curry's, Jones', and van Bavel's (and probably others)
in the USA. The 80's saw Ritchie, Hanks, Don Baker, Ken Boote, and
others, with the CERES/DSSAT suite, Gossym, Glycim, and some others
resulting.
Groups active in the 90's should be available from Robert Caldwell
and MC Fortin or from Gerrit Hoogenboom after the two related
symposia at the Amer. Soc. Agron meetings at Anaheim. Perhaps they
would fill these in, to provide a start to current work.
My summary earlier today was clearly directed toward the solution
needed for my dissertation work. There are likely some groups and
citations missed. If anyone is seriously interested in compiling a
history, ask this vast and unpaid reseearch group (this list) for the
things missing from it.
Bob, have there been responses to your request that went directly to
you and not via this list? If so, could you summarize and distribute?
Thanks
John
==============================================================
E. John Sadler, Ph.D.
USDA-ARS sadler@florence.ars.usda.gov
Coastal Plains Soil, Water,
and Plant Research Center 803-669-5203x112 (voice)
2611 West Lucas St. 803-669-6970 (fax)
Florence, SC 29501-1241
U.S.A.
==============================================================
Date: Fri, 03 Oct 1997 03:49:35 -0600
From: Automatic digest processor (LISTSERV@crcvms.unl.edu)
Subject: AGMODELS-L Digest - 30 Sep 1997 to 2 Oct 1997
Date: Fri, 3 Oct 1997 03:49:35 -0600
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There are 3 messages totalling 114 lines in this issue.
Topics of the day:
1. More on history
2. available for long/short term projects
3. Modelling History
Date: Wed, 1 Oct 1997 17:21:00 -0700
From: "Vera, Raul (3363)" (R.VERA@CGNET.COM)
Subject: More on history
Let me add my 5 cents worth.
In my view, some important early references to modelling and simulation are
as follows:
Naylor,TH (1966): Computer Simulation Techniques, London:Wiley.
Van Dyne,GM (1966): Application and integration of multiple linear
regrtession and linear programming in renewable resource analyses. Journal
of Range Management 19, 356-362.
Duncan,WG et al. (1967): A model for simulating photosynthesis in plant
communities. Hilgardia 38, 181-205.
von Bertalanffy,L (1968): General system theory. Foundations, development,
applications. G. Braziller, New York.
Maslow,AH (1971): The farther reaches of human nature. Penguin, New York.
Arcus,PL (1963): An introduction to the use of simulation in the study
of grazing management problems. Proceedings of the New Zealand Society
of Animal Production. 23, 159-168.
Date: Wed, 1 Oct 1997 21:16:57 -0700
From: Tom Hodges (thodges@TRICITY.WSU.EDU)
Subject: available for long/short term projects
My position with the USDA-ARS is now ended so I am looking at
other opportunities. I am available to help with various sorts
of short or long term projects until I find other long term
employment (or possibly decide to stay with free-lancing). I
can contribute to model application and development projects, data
analysis, experiment design, web page development, new crop
evaluation, irrigation and fertility assessment, etc. More
details are available thru my web page.
Tom
Tom Hodges, Cropping Systems Modeler
3030 W 4th Ave, #27
Kennewick, WA 99336 USA
email: thodges@tricity.wsu.edu
voice: 509-786-9207, 509-783-3792
Fax: 509-786-9370, 509-786-9277
HomePage http://www.tricity.wsu.edu/htmls/hodges
Date: Thu, 2 Oct 1997 10:09:03 +0200
From: Abraham Singels (singels@AQUA.CCWR.AC.ZA)
Subject: Modelling History
Hallo Agmodellers
Modelling effort in South Africa
A lot of work has been done by the Department of Agrometeorology,
University of the Free State led by Jimmy de Jager since 1976. The
effort started with the maize crop. A lot of effort was put into the
water balance. Models are applied for irrigation management, crop
forecasting, drought monitoring and production risk assessment. Workers
from several institutions over South Africa supplied data and expertise
for the development and validation of these models. The PUTU family of
models consists of models for maize, wheat, natural grassland and a
generic water balance model and is housed in a Windows-based shell. The
models are written in Basic. When I started (1981) we had a Hewlett
Packard desk top with 64k RAM and a tape reader. We started in Msbasic
and "progressed" to QuickBasic. Unfortunately not all of the
developments were published in English. Here are two references:
1) Singels, A. and De Jager, J.M., 1991. Refinement and validation of
the PUTU wheat crop growth model. 1. Phenology. S.A. J. Plant and Soil
8: 59-66
2) Singels, A. and De Jager, J.M., 1991. Determination of optimum wheat
cultivar characteristics using a growth model. Agric. Systems 37:
25-38
For more details and references contact Jimmy de Jager at
Jimmy@landbou.uovs.ac.za
Geoff Inman-Bamber developed the Canegro model based on Ceres - Maize.
This model is currently included in the Dssat package. We are
continuing with the Canegro modelling effort at S.A. Sugar Ass.
Experiment Station.
1) Inman-Bamber, N.G., 1991 A growth model for sugarcane based on a
simple carbon balance and the Ceres-Maize water balance. S.A. J. Plant
and Soil 8: 93-99. (Geoff.Inman-Bamber@tag.csiro.au)
Regards
Abraham Singels
Crop Modelling
S.A. Sugar Association Experiment Station
Mount Edgecombe
South Africa
Tel: 27 31 593205
E-mail: singelsa@sugar.org.za
Date: Sun, 05 Oct 1997 03:47:52 -0600
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There is one message totalling 36 lines in this issue.
Topics of the day:
1. More on history
Date: Fri, 3 Oct 1997 09:15:56 -0500
From: "E. John Sadler" (sadler@SUNBRN.FLORENCE.ARS.USDA.GOV)
Subject: Re: More on history
Greetings,
Raul Vera has contributed some important citations, apparently mostly
from the range science direction. These would have been generally
under-represented in my work, and generally not available in most
computer searches.
The Duncan et al 1967 Hilgardia work is the one I mentioned, but the
rest are new to me.
Has anyone found a historical treatment of ecological modeling?
Or forestry, entomology, or wildlife?
Keep up the discussion.
Cheers
John
==============================================================
E. John Sadler, Ph.D.
USDA-ARS sadler@florence.ars.usda.gov
Coastal Plains Soil, Water,
and Plant Research Center 803-669-5203x112 (voice)
2611 West Lucas St. 803-669-6970 (fax)
Florence, SC 29501-1241
U.S.A.
==============================================================
Date: Tue, 07 Oct 1997 03:49:54 -0600
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Date: Tue, 7 Oct 1997 03:49:54 -0600
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There are 2 messages totalling 47 lines in this issue.
Topics of the day:
1. Equation for plant growth (2)
Date: Sun, 5 Oct 1997 13:52:53 +0000
From: drake@EROLS.COM
Subject: Equation for plant growth
Have the results of any research been used to formulate an
equation for plant growth? For example, the basic "water + CO2 +
light energy = growth" formula; has there ever been a calculated ratio
of CO2/light energy (x amount CO2/y amount of lumens, for example)?
If such a ratio and equation do exist, have any been formulated
that take into account temperature and nutrients? For instance, in
the above equation iron would play a role.
Any help with finding this information would be greatly
appreciated. Thank you.
Date: Mon, 6 Oct 1997 14:41:34 -0500
From: Ranjan Muttiah (muttiah@BRCSUN0.TAMU.EDU)
Subject: Re: Equation for plant growth
Park Nobel (Biophysical plant physiology and ecology) has the efficiency
at slight below an average of 34%:
8 photons of intercepted light per mole of CO2.
Mostly light in the red range is used (680 nm = 4.41 x 10^14 hz):
by E = hv = 176 kJ/mol. For 8 photons, 8*176 = 1408 kJ/mol.
Net Gibbs energy change H2o + co2 reaction is 479 kJ/mol for
glucose. Therefore "efficiency" = 479/1408 ~= 0.34
If you change the environment (temperature mostly) the Gibbs
free energy will change.
There is a detailed theory on photosynthesis in
the latest Physics Today article (using Excitons in QM).
Ranjan
Date: Wed, 08 Oct 1997 00:03:25 -0600
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Date: Wed, 8 Oct 1997 00:03:25 -0600
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There is one message totalling 32 lines in this issue.
Topics of the day:
1. Re[2]: Equation for plant growth
Date: Tue, 7 Oct 1997 08:40:31 +0100
From: Laurence Benjamin (laurence.benjamin@HRI.AC.UK)
Subject: Re[2]: Equation for plant growth
In response to the enquiry re equations for plant growth, you may be interested
in knowing that my colleague and I published an equation for the growth of
individual plants relating the growth of each plant to specific environmental
factors;- light, temperature, etc. The equation was based upon ohm's law with
each factor considered as one of a series of conductances for growth in series.
The model gives good fits to the growth of isolated plants and those in
communities.
Aikman and Benjamin (1994) A model for plant and crop growth, allowing for
competition for light by the use of potential and restricted projected zone
crown areas. Annals of Botany 73 185-194.
Laurence Benjamin
Horticulture Research International
Wellesbourne
Warwick
CV35 9EF
United Kingdom
tel direct line +44 1789 472024
tel switch board +44 1789 470382
fax +44 1789 470552
email laurence.benjamin@hri.ac.uk
http://www.hri.ac.uk
Date: Thu, 09 Oct 1997 03:49:01 -0600
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There is one message totalling 68 lines in this issue.
Topics of the day:
1. References
Date: Tue, 7 Oct 1997 13:22:21 +0100
From: Federico Preti (preti@UNITUS.IT)
Subject: References
Excuse me, how can I write to all the AG-MODELS list?
Some time ago it was possible for me...
Thanks, Federico Preti
I would like to send them the following message:
Dear colleagues,
) please, someone could give me the correct version of the following
)References:
)
)
). Hoffman, Rhoads and others (???) in ASAE monograph "Management of Farm
)Irrigation Systems"
)
). Kanwar, R.S., (???), "Agrochemicals and water management", ???, 367-387
)
). ASA and/or SSSA handbook on "Irrigation of agricultural lands"
)
). ASA and/or SSSA handbook on "Soil Analysis Methods"
)
)Thanks a lot!
)Federico
At 10.22 25/09/97 -0600, you wrote:
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)
Date: Fri, 10 Oct 1997 00:03:18 -0600
From: Automatic digest processor (LISTSERV@crcvms.unl.edu)
Subject: AGMODELS-L Digest - 8 Oct 1997 to 9 Oct 1997
Date: Fri, 10 Oct 1997 00:03:18 -0600
Reply-To: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
Sender: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
From: Automatic digest processor (LISTSERV@CRCVMS.UNL.EDU)
Subject: AGMODELS-L Digest - 8 Oct 1997 to 9 Oct 1997
To: Recipients of AGMODELS-L digests (AGMODELS-L@CRCVMS.UNL.EDU)
There are 2 messages totalling 96 lines in this issue.
Topics of the day:
1. question about [NO3] in the stream from a natural watershed (2)
Date: Thu, 9 Oct 1997 11:04:23 -0400
From: wk14@CORNELL.EDU
Subject: question about [NO3] in the stream from a natural watershed
Dear Friends,
I am working on simulation of soil-nitrogen dynamics in a natural, small
watershed (15ha, and only permanent vegatation) in the Northeast US.
However, I only have experimental [NO3]-data in the stream during the
summer season for comparison. I would like to know the nitrate behavior
during the winter also.
Would you please help me for the following questions about [NO3] in the
stream?
(1) Is [NO3] roughly constant throughout the year for a natural watershed
(assuming that there is no input from agriculture or industry)?
(2) Generally, is [NO3] in winter heigher than that in summer, or the
other way around?
Thank you very much. I appreciate any information.
Wen-Ling Kuo
Agricultural & Biological Engineering
Cornell University
Ithaca, NY14853
wk14@cornell.edu
Date: Thu, 9 Oct 1997 08:54:18 -0700
From: Tom Hodges (thodges@TRICITY.WSU.EDU)
Subject: Re: question about [NO3] in the stream from a natural watershed
Are you thinking of total N (grams/day) or concentration (grams/liter)
in the stream? After heavy rain or during rapid thawing there will be
a lot of water and N may be diluted.
During a hard freezing period (assuming there is any stream flow), I
think little N will be leached from the soil as it will be frozen
several inches deep (unless there is thick snow cover?) and any
stream flow will come from deep ground water. This would be the
period with the least total N (gm/day) as it would only be coming
from ground water thru year round springs. During the rest of the year
total N would fluctuate based on 2 factors - (1) net NO3 released by soil
microbial activity (this activity constantly releases and immobolizes
NO3), and (2) volume of water movement thru the soil to the stream.
Concentration of N in the stream will fluctuate wildly depending on the
volume of water flow and will be hard to relate to total N.
Tom
Tom Hodges, Cropping Systems Modeler
3030 W 4th Ave, #27 email: thodges@tricity.wsu.edu
Kennewick, WA 99336 USA
voice: 509-786-9207 Fax:509-786-9370, 509-786-9277
== HomePage http://www.tricity.wsu.edu/htmls/hodges ==
On Thu, 9 Oct 1997 wk14@CORNELL.EDU wrote:
) Dear Friends,
)
) I am working on simulation of soil-nitrogen dynamics in a natural, small
) watershed (15ha, and only permanent vegatation) in the Northeast US.
) However, I only have experimental [NO3]-data in the stream during the
) summer season for comparison. I would like to know the nitrate behavior
) during the winter also.
)
) Would you please help me for the following questions about [NO3] in the
) stream?
)
) (1) Is [NO3] roughly constant throughout the year for a natural watershed
) (assuming that there is no input from agriculture or industry)?
)
) (2) Generally, is [NO3] in winter heigher than that in summer, or the
) other way around?
)
) Thank you very much. I appreciate any information.
)
)
) Wen-Ling Kuo
) Agricultural & Biological Engineering
) Cornell University
) Ithaca, NY14853
) wk14@cornell.edu
)
Date: Sat, 11 Oct 1997 00:01:23 -0600
From: Automatic digest processor (LISTSERV@crcvms.unl.edu)
Subject: AGMODELS-L Digest - 9 Oct 1997 to 10 Oct 1997
Date: Sat, 11 Oct 1997 00:01:23 -0600
Reply-To: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
Sender: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
From: Automatic digest processor (LISTSERV@CRCVMS.UNL.EDU)
Subject: AGMODELS-L Digest - 9 Oct 1997 to 10 Oct 1997
To: Recipients of AGMODELS-L digests (AGMODELS-L@CRCVMS.UNL.EDU)
There is one message totalling 70 lines in this issue.
Topics of the day:
1. ANNOUNCEMENT: PhD opportunity in NZ: Grasslands modelling
Date: Fri, 10 Oct 1997 22:23:59 +1300
From: Graeme D Buchan (BUCHAN@TUI.LINCOLN.AC.NZ)
Subject: ANNOUNCEMENT: PhD opportunity in NZ: Grasslands modelling
Greetings from New Zealand.
I am distributing the `advert' below (for a PhD project in NZ) to the
AGMODELS-L Discussion Group, since the project will involve
development of models for grasslands, including extension of models
we have recently developed here describing the energy balance/ soil
temperature regime of grasslands.
****************************************************************
Announcing......
a Prospective PhD project:
** `Grasslands in a CO2-enriched World' **
Lincoln University in collaboration with AgResearch NZ are seeking a
graduate to commence in 1998 a well-supported project investigating
the effects of climate change (especially elevated CO2) on any of the
following aspects of grasslands:
* surface energy exchanges
* plant water use
* plant development and forage supply
The project will involve:
i) modelling; and
ii) field measurements at AgResearch's major new `FACE' installation
(i.e. the `Free Air CO2 Enriched' site, near Palmerston North), and
also at sites with naturally-occurring CO2 springs in Northland.
We are seeking a versatile science, engineering or other graduate
qualified in environmental or agricultural science, plant
science/plant physiology, or any related discipline.
Prospective funding (to be applied for) will include a 3-yr Doctoral
Scholarship, which will (if awarded) include stipend (NZ$ 16,000
p.a.) and tuition fees, BUT with the fees AT NZ RESIDENT LEVEL ONLY.
N.B. To qualify for NZ resident fees, applicants must be either
residents of NZ or Australia. (Though some French or German
graduates may also qualify). In other cases, the (high!) fees of
NZ$ 28,500 p.a. levied on overseas students would regrettably not be
covered by the scholarship.
Please direct enquiries AS SOON AS POSSIBLE (before 25 Oct '97) to:
Dr Graeme Buchan, Reader in Environmental Physics,
Dept of Soil Science, PO Box 84,
Lincoln University, Canterbury, New Zealand
Fax: (64) 3 3253 607
Email: Buchan@lincoln.ac.nz
**********************************************************
Dr Graeme D Buchan,
Reader in Environmental Physics & Environmental Education,
Dept. of Soil Science, PO Box 84, Lincoln University,
Canterbury, New Zealand
(Citizen of Scotland and NZ)
email: Buchan@Lincoln.ac.nz
Tel. (64) 3 3252 811 Fax (64) 3 3253 607
**********************************************************
Date: Tue, 14 Oct 1997 00:02:30 -0600
From: Automatic digest processor (LISTSERV@crcvms.unl.edu)
Subject: AGMODELS-L Digest - 10 Oct 1997 to 13 Oct 1997
Date: Tue, 14 Oct 1997 00:02:30 -0600
Reply-To: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
Sender: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
From: Automatic digest processor (LISTSERV@CRCVMS.UNL.EDU)
Subject: AGMODELS-L Digest - 10 Oct 1997 to 13 Oct 1997
To: Recipients of AGMODELS-L digests (AGMODELS-L@CRCVMS.UNL.EDU)
There is one message totalling 102 lines in this issue.
Topics of the day:
1. FW: Position vacant - Agrometeorological data modeller
Date: Mon, 13 Oct 1997 18:15:00 +0200
From: "Gommes, Rene (SDRN)" (Rene.Gommes@FAO.ORG)
Subject: FW: Position vacant - Agrometeorological data modeller
----------
From: owner-climlist
To: CLIMLIST
Subject: Position vacant - Agrometeorological data modeller
Date: 13 October 1997 10:44
Return-Path: (owner-climlist@lists.psu.edu)
Date: Mon, 13 Oct 1997 10:44:00 -0400
From: John Arnfield (johna@GEOGRAPHY.OHIO-STATE.EDU)
Subject: Position vacant - Agrometeorological data modeller
Sender: CLIMLIST Climatology Distribution List (CLIMLIST@lists.psu.edu)
To: CLIMLIST@lists.psu.edu
Reply-to: John Arnfield (johna@GEOGRAPHY.OHIO-STATE.EDU)
MIME-version: 1.0
X-Mailer: ELM [version 2.4 PL23]
Content-type: text/plain; charset=US-ASCII
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------------------------------------------------------------------------
---- --
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
CLIMLIST Mailing Number 97-10-21
Forwarded From: aus.ads.jobs,sci.geo.meteorology,sci.math
Origin: Alan Beswick (alanbe@dpi.qld.gov.au)
))))) DO NOT USE REPLY FUNCTION (((((
))))) REPEAT - DO NOT USE REPLY! (((((
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
AGROMETEOROLOGICAL DATA ANALYST
QUEENSLAND CENTRE FOR CLIMATE APPLICATIONS.
Resource Sciences Centre,
Indooroopilly,
Brisbane
AUSTRALIA.
PO3 - $40,444-41,161 p.a.
VRN: DNR 350/97.
The position is temporary until 30/6/2000.
Key Duties: Undertake scientific and statistical research on
issues pertaining to
the development of interpolated data surfaces from sparse
agrometeorological data,
the development of synthetic weather and climate generators, and
the production of agrometeorological data and hydrological data from
various climate forecasting models.
Skills/Abilities:
Degree in Science, Meteorology, Mathematics or equivalent.
Demonstrated knowledge of
meteorological science
the use of agrometeorological and hydrological data in
agricultural
simulation modelling and decision support
the interactions of climate on biophysical systems.
Demonstrated experience with statistical analysis techniques
including
multivariate methods, splines, and kriging
development of interpolated data surfaces from sparse data
points
development of statistical weather generators
the quantitative analysis of meteorological and spatial data.
Extensive knowledge of scientific computing techniques
Position Description: (07) 3406 2904
International: +61-7-3406 2904
WWW http://www.dnr.qld.gov.au/longpdk/QCCA_positions
Enquiries: Mr Alan Beswick (07) 3896 9741
International: +61-7-3896-9741
email alan.beswick@dnr.qld.gov.au
Closing Date: 5.00PM, Monday 5th November
Date: Wed, 15 Oct 1997 00:03:00 -0600
From: Automatic digest processor (LISTSERV@crcvms.unl.edu)
Subject: AGMODELS-L Digest - 13 Oct 1997 to 14 Oct 1997
Date: Wed, 15 Oct 1997 00:03:00 -0600
Reply-To: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
Sender: Agmodels-L Discussion List (AGMODELS-L@CRCVMS.UNL.EDU)
From: Automatic digest processor (LISTSERV@CRCVMS.UNL.EDU)
Subject: AGMODELS-L Digest - 13 Oct 1997 to 14 Oct 1997
To: Recipients of AGMODELS-L digests (AGMODELS-L@CRCVMS.UNL.EDU)
There is one message totalling 39 lines in this issue.
Topics of the day:
1. Experience with UN-SCAN-IT?
Date: Tue, 14 Oct 1997 12:26:55 -0400
From: "Daniel P. Knievel" (dpk@PSU.EDU)
Subject: Experience with UN-SCAN-IT?
Dear AgModels Subscribers:
Have any of you had any experience with the digitizing software
"UN-SCAN-IT"? About two years ago I obtained a demo disk of the software,
but it was unconvincing. It worked with internal data sets and the demo
user could not imput their own data. I couldn't tell whether the demo ran
a "canned" routine or whether it actually utilized the software to digitize
a real scanned image file. I want to use "UN-SCAN-IT" to prepare graph
materials for classroom presentation
Thanks to anyone in advance for supplying evaluation comments.
-DPKnievel
**********************************************
Internet:
dpk@psu.edu
Web:
http://www.cas.psu.edu/docs/CASDEPT/AGRONOMY/People/Faculty/KnievelDP.html
U.S. Mail:
Daniel P. Knievel
116 Agricultural Sciences & Industries
University Park, PA 16802-3504
USA
Phone:
Office: (1-814) 865-1547
FAX: (1-814) 863-7043
**********************************************
Prepared by Steve Modena, AB4EL
Suggestions and comments to: modena@SunSITE.unc.edu