Albert J. Calitz
and
Andries L du Pisani
ldupisan@mweb.com.na

Ministry of Agriculture, Water and Rural Development, Windhoek, Namibia

Introduction - In the last decade, in a dry African country like Namibia it became important for the Ministry of Agriculture, Water and Rural Development to compile a computerized inventory of the country’s natural resources to assist planners, managers and researchers in the attempt to increase food security. This need gave birth to the Agro-ecological Zoning of Namibia programme (agricaez@mweb.com.na).

As this is a multi disciplinary initiative the location and potential production of several crops are also considered as important. Various crops and cultivars are researched and evaluated to generate the data needed for the programme.

Data generation is a difficult task in a resource poor country like Namibia and the Agro-ecological Zoning of Namibia programme believes that simulation forms a necessary part of interpreting crop research results and make it applicable for planning, extension and monitoring. This approach enables better use of scarce manpower and requires fewer actual trials, reduces overall costs and yields a better result in the given timeframe of the programme.

Current Situation - The latest crop modeling and crop management responses technology called, "Decision Support System for Agrotechnology Transfer " (DSSAT)" arrived in Namibia in June 1999. The advantages of the DSSAT system, which can model the growth of seventeen crops, are the standardized inputs (soil and climate) and a strong analyzing component. Once DSSAT has been validated for Namibia with historical and future data, suitability and economic simulations could be run on computer.

However DSSAT and its initiators (the Agro-ecological Zoning programme) needed to overcome some challenges. In Namibia crop research was still done in the traditional way. Traditional means an empirical approach with shortcomings in extrapolation to real-life situations. Other problems were unpublished data, a need of a minimum set of historical data a serious shortage of model minded people and the always present money problem.

Meeting the Challenge - The challenge was met with the following work plan. Demonstrations of the DSSAT models were held. Data needs to calculate the genetic coefficients for the cultivars used were specified and it was clearly indicated that initially small and low impact changes to the researchers current and future trails were necessary to do this validation.

Researchers were visited one by one to unearth all possible research results for testing the models. This personal approach assisted us in changing his or her mind on the usefulness of the modeling approach, especially by using the analyses available in the DSSAT system and the need for him or her to assist us in the testing of the models because of their practical experience with specific crops. This helped enormously in changing the outlook of the researchers and extension staff of the Ministry on the usefulness of modeling in understanding the performance of crops.

The next step was to coordinate the planning of the 2000/2001 season’s experiments so that more appropriate data could be generated for model testing. Training is envisaged for research and extension staff to use and develop the DSSAT system themselves and make it part of a new tradition in the Ministry. Researchers were encouraged to start with the model applications they felt most confident with and then continue testing the models for further applications. Finally, for some of the crops/cultivars the genetic coefficients had been acquired from our South African colleagues who have done some good work during the last decade.

Conclusion

In future the use of the DSSAT system would depend on the success with testing the models and the confidence with which it can be used for the major crops and cultivars grown in Namibia.

Then it can be used in planning to come up with the "best" farming systems for the various areas of Namibia which would include crop/cultivar choice, planting dates, fertilizer application etc. This can be integrated with the resource database and GIS system being developed as part of the Agro-ecological Zoning programme that includes the soil and climate databases of the Ministry.

This would all contribute to an extremely useful tool for the extension effort of the Ministry.

Namibian Agricultural Union

www.agrinamibia.com.na

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