I would be interested to play with this project. I am not a crop modeler, I
am software engineer but I have been working for some time with crop
simulation models to have a good understanding of how they work. I have a
running version of the Kraalingen model written in Java and if anyone is
interested to add to this simple model intercrop capabilities, please
contact me.
I have been interested to know whether simulating multiple crops at the same
time goes through Threads or not. If the equations of the intercrop process
are ready it should not take too much time for me to develop a running
example of the Kraalingen intercrop system.
Petraq Papajorgji
IFAS Information Technology Office
University of Florida
Gainesville, Fl 32611
Tel: (352) 846-3219
Fax: (352) 392-3920
Web: http://petraq.ifas.ufl.edu
UML: http://conference.ifas.ufl.edu/uml/
-----Original Message-----
From: James Hansen [mailto:[log in to unmask]]
Sent: Tuesday, June 08, 2004 1:20 PM
To: [log in to unmask]
Subject: Re: Modelling intercrops
Chris,
This is exactly what we had to do in CropSys. It required a major
reorganization of all of the component models. To get the sequencing
consistent with the way the sole crop models operated, we reduced the
interface between crops and their environment to about five procedural
calls in each daily time step, with relevant state variables passed as
arguments between the crop physiology components and the now separated
ecosystem component. This allowed us to separate the submodels of
resource capture under competition from the submodels of resource use
within the individual crops. It was, at that time, a very tedious and
costly process. We did it all in FORTRAN. It seems like it would be
much easier in an appropriate object-oriented structure and language.
Three problems -- the intercrop problem, dynamic interactions in space
associated with, e.g., lateral movement of water or eroded sediments,
and dynamic allocation/scheduling of scarce farm resources among crop
enterprises -- come to mind that require the ability of component models
to dynamically read or modify crop state variables during the growing
season.
I understand that the latest (v. 4) suite of DSSAT models are organized
more consistently and much more loosely-coupled, and may therefore lend
themselves to this sort of dynamic interation.
Chris G. Nicholas wrote:
> Or, the next generation of DSSAT needs to be able to "single-step";
> i.e. allow some external entity to "peek" at its state variables,
> perform cross-factor interaction calculations, and then "poke" the
> changed variables back into DSSAT for the next step. Other
> interesting aspects are how to put the interacting programs into
> "suspended animation" while performing such peeking and poking, but
> there are known checkpointing and gdb tricks to do this.
>
> Obviously this is non-trivial, and would probably involve at least
> several weeks of work by someone familiar with DSSAT internals. But
> it would be interesting to be able to link 2 or more DSSAT models,
> and then have something external look at the individual LAIs,
> nitrogen and moisture uptakes, etc, and then go back into each and
> "poke" the next step.
>
> One would want to write that in a general-purpose manner, such that
> one might be able to externally blend in other factors, such as
> pests, as well.
>
> Indeed, if anyone out there has a companion computer science
> department writing GRID-based research proposals (UFL?), hooking up
> DSSAT using such a mechanism to the stuff of:
> http://www.uvm.edu/giee/SME3 would allow for modeling crop
> interactions with surface hydrology, herbavores, hill shading, etc in
> scalable, location-specific manner.
>
> Chris
>
>
> -----Original Message----- From: Evert, Frits van
> [mailto:[log in to unmask]] Sent: Tue 6/8/2004 6:07 AM To:
> [log in to unmask] Cc: Subject: Re: Modelling intercrops
> Kropff, M.J. and H.H. van Laar, 1993. Modelling crop - weed
> interactions. Wallingford, CAB International. ISBN: 0-85198-745-1
> or 971-22-0038-8
>
> -----Original Message----- From: DSSAT - Crop Models and Applications
> [mailto:[log in to unmask]] On Behalf Of ken boote Sent:
> Tuesday, June 08, 2004 14:57 To: [log in to unmask] Subject: Re:
> Modelling intercrops
>
>
> Juan,
>
> The present DSSAT models do not simulate intercrops or differential
> height competition for light interception (dry matter accumulation)
> purposes. So, you can not do it in the DSSAT models.
>
> To do this correctly, you would need to predict the height of each
> crop and the corresponding (and competing) vertical LAI distribution
> of each component. I recommend that you see the approach followed in
> the INTERCOM model of Martin Kropff, Wageningen Agricultural
> University, The Netherlands. His model predicts those aspects of
> species competition nicely, but probably does not go to final yield
> like you would like. Martin Kropff did write one of those Wageningen
> special publications on the topic. Either Pudoc Publications
> (Wageningen in-house) or Halstead Press.
>
> Can anyone give us the full citation of Kropff's book and where to
> order?
>
> Ken Boote
>
>
> At 11:37 PM 6/7/04 -0700, you wrote:
>
>> My name is Juan and I am trying to simulate the performances of a
>> wheat/soybean intercrop. The design of the intercrop (or relay
>> intercrop) is 3:1 and has a distance of 75cm, I have 3 rows of
>> wheat to 17,5cm of distance and 1 row of soy to 17,5cm of distance
>> from the rows of wheat and again the same design. The soy is sown
>> 30 days before the harvest of the wheat. Because of the design,
>> the wheat fails to capture the totality of the radiation and the
>> soy grows inside the wheat during 25-30 days until the wheat
>> harvest and during this period the soy receives less radiation than
>> the one that would receive it if sown alone. Any idea for this
>> simulation is welcome. Greetings Juan Pablo Monzon
>
>
--
Dr. James W. Hansen
Associate Research Scientist - Agricultural Systems
International Research Institute for Climate Prediction
The Earth Institute at Columbia University
121 Monell Bldg., Lamont-Doherty Earth Observatory
PO Box 1000 / 61 Route 9W
Palisades, NY 10964-8000
USA
voice: +1-845-680-4410
fax: +1-845-680-4864
e-mail: [log in to unmask]
WWW: http://iri.columbia.edu/cgi-bin/ForOne.cgi?jhansen
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