SIMULATION BY NCSWAP OF SEASONAL NITROGEN DYNAMICS IN CORN .2. CORN GROWTH AND YIELD

The accurate simulation of crop growth is important in the effort to apply computer simulation models to improvements in the management of N resources in agricultural systems. The objective of this study was to validate the crop growth submodel of the model NCSWAP using seasonal corn (Zea mays L.) growth and final grain yields from a 3-vr N rate-study conducted in central Pennsylvania. The results of the validation suggest that the model poorly simulated crop growth response under conditions of limited water or N availability. However, NCSWAP accurately simulated observed seasonal corn growth and harvested yields in treatments with no N or water limitations. The crop growth submodel has the potential to be useful in simulation of crop production, because with a minimum of inputs it can be calibrated for any crop and can incorporate variables that influence crop growth and are specific to a local environment. Improvements in the simulation of crop growth under N and water deficits would enhance the usefulness of NCSWAP to researchers exploring seasonal N cycling in soils and crops.