CROP MANAGEMENT AND INPUT OPTIMIZATION WITH GLYCIM - DIFFERING CULTIVARS

The soybean simulation model GLYCIM is mechanistic and operates at the physical and physiological process level. The model is organized in modules along disciplinary lines using a generic modular structure. The model was initially validated with data sets collected at the Plant Science Farm at Mississippi State University and calibrated to the cultivar ''Forest''. In 1991 GLYCIM was released to soybean farmers and scientists at state experimental stations for crop management and input optimization. The soybean growers have claimed a 14-29% increase in yields and over a 400% increase in irrigation efficiency from using GLYCIM to manage irrigation. During the past two years, significant changes to GLYCIM have improved its predictions. Model improvements pertain to the effect of water stress on several physiological processes in the soybean plant and the method of accounting for numbers and weights of individual pods and seeds. In addition, cultivar parameter files have been developed for several cultivars. As a result of these changes, improved simulations have been obtained and grower usage of the model has been enhanced. The development of cultivar parameter files and the resulting simulations are discussed.