1. General Model Information

Name: Potato Growth Model


Main medium: terrestrial
Main subject: biogeochemistry
Organization level:
Type of model: not specified
Main application:
Keywords: potatoes, crop growth, agriculture, agroecosystem


Tom Hodges
Cropping Systems Analyst
Rt. 2, Box 2953-A
Prosser, WA 99350 USA

Phone: 509-786-9207
Fax: 509-786-4635
email: TOM.HODGES@usda.gov


Tom Hodges,


SIMPOTATO Potato Growth Model, version 1.51

The following is a brief introduction to the SIMPOTATO growth simulation model designed to help you start using it immediately. This way you can see what it does. You will need to study the model documentation in the file MANUAL.ASC to make full use of the model or to successfully make major changes in the source code. Input and output files are described in REPORT5.ASC and in MANUAL.ASC.

The SIMPOTATO model is based on the CERES-Maize model, as distributed by IBSNAT. The physiology and phenology subroutines are substantially changed from CERES-Maize to account for differences in potato growth. It largely uses the standard input files from IBSNAT (see chapter 9 of the manual for exceptions). The major changes from the IBSNAT programs are:

  1. graphics: a routine has been added to allow variables to be plotted on the screen on PCs equipped with a CGA, EGA, or VGA graphics board.
  2. water balance: Dr. Ritchie's WATBAL subroutine has been split into 7 subroutines comprising the various independent functions in the original subroutine. I think that this improves readability and makes it easier for the user to replace or modify a particular function such as PET.
  3. general rewriting of code in line with modular programming principles to reduce the number of goto statements and to improve readability.
  4. configuration file (IPARM.P) to set model options such as graphics, batch runs, choice of output files, irrigation & fertigation modes, prediction of optimal irrigation & fertigation. IPARM.P is described in three chapters of MANUAL.ASC.

II. Technical Information

II.1 Executables:

Operating System(s): sim151.exe (self extracting) installation procedure for drive c: installation procedure for drive d: The program is sent to you on a floppy disk as a self extracting zip file. It opens into Data, Program source, Documentation, and Graphics Library subdirectories with the following files: Program Source Disk or Source Directory GRAPH LIB JPTOP FOR JPSELECT FOR JPREAD FOR JPEFF FOR JP1 FOR JP2 FOR JP3 FOR JPGROW FOR JPPLOT FOR MAKEFILE EXEC Disk or EXEC Directory JP1 EXE GRPHPROG EXE STARTGRF EXE GRPHPROG.FOR STARTGPH.FOR REP2CONV.EXE REP3CONV.EXE REP2CONV.FOR REP3CONV.FOR DOCUMENTATION files README 1ST -- instructions, this file MANUAL ASC -- documentation, 100+ pages if printed REPORT5 ASC -- IBSNAT Technical Report 5, Documentation for IBSNAT Input & Output Files, Version 1.1 SIMFILES.WQ1 -- Quattro spreadsheet to simplify creating new data files Data Disk or Data Directory Approximately 130 data files GRAPHICS LIBRARY Disk or Directory (GRAFPAC) Source files for graphics library (28 files) To run the program, follow the first 4 steps below:
  1. Make copies of the disk.
  2. On a hard disk system: Create a subdirectory named SIMPOT and copy the contents of the floppy disk to it. I.e. C:[RET], MD SIMPOT[RET], CD SIMPOT[RET], COPY A:\ /v[RET], then run the EXE file: SIM151 -d[RET]. Enter the data subdirectory and type ..\exec\JP1 [ENTER] and follow the instructions. The model will prompt you to select an experiment and treatment and if you have selected graphics (see below) to select variables to plot. You may also copy the file JP1.EXE to the data directory and then remove the other directories and files if you have no interest in studying the source code. Keep the documentation files.
  3. The input data files are the standard IBSNAT data files. The standard files are documented in a manual "Technical Report 5: Documentation for IBSNAT Crop Model Input and Output Files, Version 1.1". Report 5 is on disk as part of the SIMPOTATO package and is available from IBSNAT (address below) as a published report. A summary file, OUT1, is produced for all experiments selected in a model run. Additionally, nine optional output files may be created by the model at this time. (REPORT1.OUT, REPORT2.OUT, REPORT3.OUT, REPORT4.OUT, REPORT9.OUT, OUT2, OUT3, OUT4, HPGL; instructions for producing these output files are to be found in the IPARM chapter of MANUAL.ASC. IPARM.P is currently set for no optional output). The model also uses several other files - IPARM.P, STOP.P, and BATCH.P are used to configure the program and are described more fully in the GLOSSARY and IPARM chapters of the manual.
  4. The graphics routine is set up to run with any of the potato experiments in the file PTEXP.DIR. To use graphics, set IPLOT=1 and SCROUT=0 in the file IPARM.P before running the program or copy the file IPARM.PLT onto the file IPARM.P. To turn off the graphics, set IPLOT=0 and SCROUT=1 or copy the file IPARM.SCR onto the file IPARM.P. If graphics is turned on, after you select an experiment and treatment, the model will ask you to select a variable for the X-Axis and up to 12 variables for the Y-Axis. Variable 31 (day of the year) is best for the X-axis. The screen drawing files provided with the model label the screen for variables 2 thru 6 so those give the best results. You may create other screen drawing files for other variables (see below). If you want to select fewer than 12 variables for the Y-axis, then enter 0 when you have finished selecting. If periodic observed data is available for an experiment (file *.PTB is present), the model will show it as letters of the same color as the corresponding predicted line for selected variables that have observed values. Answer L for the line mode (don't hit the enter key this time). For a VGA, EGA, or CGA graphics system, type "POTATO.VGA", "POTATO.EGA" or "POTATO.CGA" after the prompt "enter the name for the screen drawing file". You may also select V, VTEXT, or DTT for VGA graphics systems. Now the screen will be drawn and the model results plotted as the model runs. To generate a graph like that in the SPUD TOPICS article, choose Day of Year (31) for the X-Axis, Specific Gravity (67) for the Y-Axis, and SPGRV for the screen drawing file. To create additional screen drawing files for different combinations of variables and different labels, use the program GRPHPROG.EXE on the GRAPHICS disk. Use the program STARTGPH.EXE to display the screen that you have designed. After you have selected X and Y variables and a screen drawing file, you may press the [ENTER] key to keep the same choices for additional treatment and experiment selections. You may choose between growing season plots, full year plots, multiple growing season plots, or multiple full year plots by setting the variable PLTPER in the IPARM.P file to 0, 1, 2, or 3 respectively. If multiple season or multiple year plots are selected, the Batch mode must also be selected (BATCH=1 in IPARM.P) and the experiments and treatments must be selected by being listed in the file BATCH.P. For the multiple season or year plots, the Y variables for all selected experiments and treatments will be plotted on the screen in different colors.
  5. The graphics subroutines and programs use the standard FORTRAN library routines and some graphics routines in the library GRAPH.LIB. The graphics library is public domain, to be distributed freely. If you have non-commercial routines that could be added to the library, I would be happy to consider working them in.
  6. IBSNAT sells a program to assist users in preparing data files, called the DSSAT program (Decision Support System for Agrotechnology Transfer) . To reach IBSNAT:
    IBSNAT Dr. Gordon Tsuji 2500 Dole St. Krauss Hall, Room 22 University of Hawaii Honolulu, HA 96822 Telephone: 808-948-8858
  7. The multiple subfields option is not available in the distribution version of the model so that less memory is required. If you want to use multiple subfields, change the parameter NF from 1 to 10 or more in all subroutines where it occurs. Each increase of 1 adds about 20K to the memory required to run the model.
  8. As distributed, the model is configured with graphics on, all optional output files off, irrigation & fertigation forecasting off, and not in batch mode. To reconfigure, see the chapter in the on-disk manual on changing the values in the file IPARM.P. Copying IPARM.SCR over IPARM.P will switch the configuration to graphics off and regular screen output on. Copying IPARM.PLT over IPARM.P will switch configuration back to graphics mode. Feel free to call me with questions about the model or with suggestions for improvements in the model or in how the model is programmed. I am also most interested in potato growth data or in possible collaborative experiments to support further improvements or new components for the model. I am currently doing a tillage by irrigation by variety field experiment to study effects of tillage, rotation, and irrigation level on soil temperature, potato growth, tuber quality, and soil nitrate movement for an indeterminant and a determinant cultivar.

II.2 Source-code:

Programming Language(s): (see above)

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: 30.June 1997 -
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:49 CEST 2002

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