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MODWht3 for modern wheat planning.

How much wheat will my crop yield? How much residue will remain on the field after harvest? What would happen if I planted 2 weeks earlier?

Farmers will be able to answer these and many other questions with MODWht3, a new computer simulation developed by ARS researchers at Pendleton, Oregon. With just a few entries pertaining to a specific field, the simulation describes the day-to-day changes in a winter wheat crop, from germination through harvest-ripe grain.

As with its predecessor PLANT-EMP [See "Computerized Crystal Ball for Wheat Growth," Agricultural Research, July 1989, p. 15.], MODWht3 uses local weather data to predict crop characteristics. But MODWht3 is easier to use than the earlier version and is more powerful.

"It's like comparing roller skates to an automobile," says ARS soil scientist Ron Rickman, who worked on both models.

Most crop programs require the user to provide weather data in specific units and in a set format. For example, if the program uses temperature in degrees Celsius, it would not accept temperatures measured in Fahrenheit. The user would have to manually convert the temperatures before entering them into the program. With a few simple instructions, MODWht3 pulls the needed information from an existing weather file and performs all the conversions automatically.

The output is also flexible. The simulation provides values for any combination of over 100 variables, from the number of living stalks each day to total yield at harvest.

The key to this versatility is a modular design. MODWht3 contains six modules that describe the physical environment of the crop--soil, soil surface, atmosphere, root, shoot, and canopy. A programmer could modify the simulation to describe corn instead of wheat by substituting the root, shoot, and canopy modules with information on corn. The soil, soil surface, and atmosphere modules would work the same for any crop.

Or a programmer could substitute one part of the program with a more sophisticated module. ARS researchers at the U.S. Salinity Laboratory in Riverside, California, are replacing its simple soil module with SOIL-CO2, a more complex soil model.

MODWht3's flexibility relies on a companion program, MODCROP. The two programs work together, like the human body and brain. MODCROP provides the autonomic functions, like breathing, and MODWht3 does the thinking.

Rickman and ARS mathematician Sue Waldman wrote both MODWht3 and MODCROP.

MODCROP contains all the standard processes necessary to run a computer simulation, also in a modular format that can be modified. Usually programmers spend days rewriting this information for each new model. But just as a module of MODWht3 can be replaced, the entire MODWht3 program could be replaced with another crop management program. By using the existing commands in MODCROP, the programmer would save time.

The authors intend to publish the simulation in the American Society of Agronomy's new electronic journal. This will enable farmers, extension agents, educators, and programmers to download the complete package, including a user's manual and programmer's guide. The simulation runs under MSDOS on a personal computer with at least 640K of memory.

Ronald Rickman and Sue Waldman are with the USDA-ARS Columbia Plateau Conservation Research Center, PO Box 370, Pendleton, OR 97801: phone (503) 278-3292, fax (503) 278-4188.
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Title Annotation:computer simulation program
Author:Stelljes, Kathryn Barry
Publication:Agricultural Research
Date:Jun 1, 1994
Words:528
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