The CROPGRO model for grain legumes

Abstract

The CROPGRO model is a generic crop model based on the SOYGRO, PNUTGRO, and BEANGRO models. In these earlier crop models, many species attributes were specified within the FORTRAN code. CROPGRO has one set of FORTRAN code and all species attributes related to soyabeans, groundnuts or drybean [? Phaseolus vulgaris] are input from external 'species' files. As before, there are also cultivar attribute files. The CROPGRO model is a new generation model in several other ways. It computes canopy photosynthesis at hourly time steps using leaf-level photosynthesis parameters and hedgerow light interception calculations. This hedgerow approach gives more realistic response to row spacing and plant density. The hourly leaf-level photosynthesis calculations allow more mechanistic response to climatic factors as well as facilitating model analysis with respect to plant physiological factors. There are several evapotranspiration options including the Priestley-Taylor and FAO-Penman. An important new feature is the inclusion of complete soil-plant N balance, with N uptake and N 2-fixation, as well as N deficiency effects on photosynthetic, vegetative and seed growth processes. The N 2-fixation option also interacts with the modelled carbohydrate dynamics of the plant. CROPGRO has improved phenology prediction based on newly-optimized coefficients, and a more flexible approach that allows crop development during various growth phases to be differentially sensitive to temperature, photoperiod, water deficit, and N stresses. The model has improved graphics and sensitivity analysis options to evaluate management, climate, genotypic, and pest damage factors. Sensitivity of growth processes and seed yield to climatic factors (temperature, CO 2, irradiance, and water supply) and cultural management (planting date and row spacing) are illustrated.