Application of crop simulation models in agricultural research and development in the tropics and subtropics

Crop model development is now at the stage where models are useful enough to supplement field trial work in all sorts of situations. This document considers the following approaches to crop model applications. (1) At the field level, crop models can be used to investigate variety selection, fertilizer and irrigation use, the timing of planting in relation to prevailing weather and soil conditions, and long-term soil and nutrient effects on yield stability and sustainability. (2) At the farm level, additional applications include the design and pretesting of new and improved cropping systems, together with methods for bringing about radical changes to farmers" production systems, and an investigation into yield disparities between experimental plots and the farmers" own fields. (3) At the regional level, linkage to a geographic information system allows the aggregation of production response information for use by researchers and policymakers. The report also lists priority areas of further research for successful model-related projects. (Author abstract, modified)