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 developed to simulate water, chemical, and biological processes in the root zone of agricultural management systems. As of this writing RZWQM is in the beta- testing phase of development. This article reports on a parameterization and evaluation study performed in Ohio on field corn for the crop growth component of RZWQM. The generic crop growth model in RZWQM had not previously been parameterized or tested on field corn. This article reports the results of such a study. One year of data was used 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 calibrated. 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 Piketon, Ohio. The simulation results performed consistently with our expectations of the physical system. Since the generic crop growth model had not previously been tested on simulated field corn growth, we were unsure of its capabilities. For our site, the model was capable of being parameterized with one year's data, and reliably simulated the soil water content, nitrate in the root zone, corn growth, and yield for two other years.