EVALUATION OF THE CROP GROWTH COMPONENT OF THE ROOT-ZONE WATER-QUALITY MODEL FOR CORN IN OHIO

The Root Zone Water Quality Model (RZWQM) is a computer model develope d to simulate water, chemical, and biological processes in the root zo ne of agricultural management systems. As of this writing RZWQM is in the beta-testing phase of development, This article reports on a param eterization and evaluation study performed in Ohio on field corn for t he crop growth component of RZWQM. The generic crop growth model in RZ WQM had not previously been parameterized or rested on field corn. Thi s article reports the results of such a study. One year of data was us ed to calibrate RZWQM, and two additional years of data from the same site were used to check the predictions of the model once it was calib rated Crop growth, soil water content, and soil nitrate concentration predictions were compared to observed values collected throughout the growing season at the Ohio Management System Evaluation Area in Piketo n, Ohio. The simulation results performed consistently with our expect ations of the physical system. Since the generic crop growth model had not previously been tested on simulated field corn growth, we were un sure of its capabilities. For our site, the model was capable of being parameterized with one year's data, and reliably simulated the soil w ater content, nitrate in the root zone, corn growth, and yield for two other years