MEASURED AND RZWQM PREDICTED ATRAZINE DISSIPATION AND MOVEMENT IN A FIELD SOIL

The ARS Root Zone Water Quality Model (RZWQM) was developed recently to study the fate and behavior of agrochemicals in the environment and the effects of agricultural management on surface and groundwater quality. In this article, model performance was tested by comparing three years of field data for. water and atrazine movement (runoff and concentration profiles) and atrazine transformation obtained under different management conditions with those simulated by RZWQM. Accuracy of model simulation was quantified by standard linear regression techniques. The regression correlation coefficients (R(2)) between average measured and simulated data for water runoff, atrazine runoff atrazine persistence, and atrazine distribution in the soil profile were 0.87, 0.92, 0.97, and 0.73, respectively. Evaluation of the model, using best estimates for properties of atrazine and hydrologic characteristics of the field soil and limited calibration for water runoff suggests that the model effectively simulates the important processes operating on water and chemicals.