1. General Model Information

Name: Decision Support System for Agrotechnology Transfer Version 3.5

Acronym: DSSAT

Contact:

Author(s):

Abstract:

The goal of the International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT) Project is to accelerate the flow of agrotechnology and increase the success rate of technology transfer from agricultural research centers to farmers' fields. To do this, IBSNAT has developed computer software which helps match crop requirements to land characteristics using crop simulation models, data bases, and strategy evaluation programs. The resulting system is called the Decision Support System for Agrotechnology Transfer (DSSAT). DSSAT provides easy access to data bases and crop models so that the user may "test" on screen the performance of new cultivars, sites, or manag ement practices. This system allows user to screen new technology packages, such as a new cultivar or fertilizer management strategy, whithout spending excess time on expensive, time consuming field trials. By simulating outcomes of strategies on the computer screen, user can ask "what if" questions and explore the options on screen. Sustainable agriculture requires tools that enable decision makers to explore the future. A decsion support system must help users make choices today that result in desired outcomes, not only next year, but 10, 25, and 50 or more years into the future.

DSSAT was designed primarily for user groups in agriculture, but owing to its break with traditionaly ways of diagnosing and prescribing solutions, it has been adopted by other types of users. The emergence of issues which require assessment of conditions not in the past or present, but in the future calls for the systems approach to problem solving encompassed by DSSAT, which includes:

• Global climate studies,
• Use with geographic information systems,
• Whole-farm system models,
• Pest-crop interaction models,
• Fertilizer strategies,
• Plant breeding.

DSSAT is comprised of the following components:

1. a Data Base Management System (DBMS) to enter, store, and retrieve the "minimum data set" needed to validate, list and use the crop models to provide outcomes to alternative management input
2. a set of validated crop models
3. an application program for analyzing and displaying outcomes of long-term simulated agronomic experiments.

The following crop models are currently accessible under the DSSAT shell. They include:

• the CERES family of models:
  CERES-maize, CERES-wheat, CERES-rice, CERES-barley, CERES-sorghum, and CERES-millet;
  
• the CROPGRO series of models for legumes:
  CROPGRO-soybean, CROPGRO-peanut, CROPGRO-dry bean (Phaseolus)
  
• the CROPSIM model series for root crops: CROPSIM-cassava and SUBSTOR-potato
  
• and for other crops: CROPGRO-Tomato, CROPGRO-Chickpea, Sugarcane, Sunflower
  
• (Taro, tanier and pineapple will be added in the near future.)
  

These models are process oriented, designed to have global applications, and work independent of location, season, crop cultivar, and management system. The models simulate the effects of weather, soil water, genotype, and soil and crop nitrogene dynamics on crop growth and yield.

The Data Base Management System (DBMS) in DSSAT is used to organize and store the Minimum Data Set (MDS). The MDS is the minimum data required to run DSSAT's crop models, and has become an international standard data set for model calibration and validation. The DBMS provides easy access to four data bases.

• The Weather Data Base
  This data base contains daily weather data from the Minimum Data Set experiments, and allows easy editing, and printing of data.
• The Soil Data Base
  This data base is comprised principally of the 600 pedons in the USDA Soil Conservation Service (SCS) International Benchmark Soil Data base.
• User's Input Data Base
  This database allows the user to enter soil data collected by their own national soil survey organization. Data is entered into the User's Input program using a standardized format, so that the user can retrieve their own soil profiles and combine them with the Weather and Experiment data bases.
• The Management and Experimental Data Base
  Management information includes planting date, planting density, row spacing, planting depth, crop variety, and irrigation and fertilizer practices. The experimental data base includes the minimum data set required for validating the crop models.
• Utilities and Summary Reports
  The utility programs allow users to input data in ASCII format (i.e., a spread-sheet) and the program converts it into the correct input/output file format used by the crop models. The Summary Reports allow:
  
  1. chronological listing of activities and events for an experiment;
  2. summary of preplant soil fertility and preplant soil water content for each layer;
  3. date and fertilizer inputs by plot; and
  4. tables and/or graphs of weather data on a 10-day or monthly basis.

The Strategie Evaluation Program in DSSAT allows users to evaluate the merits of simulated strategies and identify the best one. The program uses cumulative probabilty functions to develop and select the strategy with the preferred mean and variability characteristics. With this program users can determine the effectiveness of crop management stragegies, the economic return of a new cultivar, or the suitability of a site for a specific crop. Using weather generators programs which generate coefficients from historical weather data, DSSAT can simulate the growth and development of a crop for up to 50 consecutive years. DSSAT allows up to 15 combinations of options to be simulated in a single experiment, generating in a few hours, amounts of data that have traditionally required an agronomist's lifetime of work.

Source of abstract information (partially): DSSAT Information page, IBSNAT, 1998.
Further information now at ICASA - DSSAT: http://www.icasa.net/dssat/index.html
Actual version of DSSAT: 4.0

II. Technical Information

II.1 Executables:

• 640K of random access memory (RAM); minimum free RAM required is 590K
• a hard disk (required); complete installation requires 25 MB disk space
• DOS version 3.3 or later
• an VGA graphic adapter or better
• a math coprocessor (recommended)

• Management System for new DSSAT v3.5 files,
• Crop models and User's Guides for:
  • Cereals - Maize, Wheat, Rice, Sorghum, Barley, and Millet models,
  • Grain Legumes - Soybean, Peanut, Dry Bean, and Chickpea models,
  • Root Crops - Cassava and Potato models, and
  • Sugarcane, Tomato, Sunflower and Pasture.
• Seasonal, Sequence and Spatial (AEGIS/WIN) Analysis programs, and
• 4 Volume set of DSSAT v3.5 User's Guides.

• Order Form
  

II.2 Source-code:

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

• weather data input requirements in comparison to other SOM models
• soil data input requirements in comparison to other SOM models:
• animal and plant data input requirements in comparison to other SOM models:
• landuse and management data input requirements in comparison to other SOM models:

III.2.2 Output

• soil output data in comparison to other SOM models
• plant output data in comparison to other SOM models
• animal and other output data in comparison to other SOM models

IV. References

V. Further information in the World-Wide-Web

• ICASA DSSAT Home Page: http://www.icasa.net/dssat/index.html

• Start a search for DSSAT at

• Start a search for DSSAT at

• The CROPSIM-Cassava Submodel (GUMCAS)

VI. Additional remarks

• Join DSSAT Listserver

• DSSAT Listserver Archive

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