Simulating Water and Nutrient Movement in a Corn Field with High Input Production Practices.

There is a great concern about the impact of agriculture on the environment. Most farmers’ goal is to achieve the highest possible yield. In Georgia, a relatively small group of farmers have been able to achieve corn yields of around 31000 kg/ha (500 bu/ac). In addition to better varieties and the use of irrigation, higher yields are often pursued by adding more agrochemicals and more specifically, higher rates of fertilizers. The use of high rates of fertilizers can result in unintended environmental consequences as unused fertilizers can move from the soil to groundwater with leaching and to streams and rivers with surface runoff. The impact on the environment has been documented by researchers for at least the past 50 years. As farmers pursue higher yields, the threat to the environment may increase. Previous studies have tried to find ways for better management practices which could possibly minimize the environmental problems. This three-year study focuses on identifying the environmental effects, regarding water quality, of pursuing high corn yields in Georgia. Groundwater and surface runoff samples are being collected throughout the year and analyzed in the lab for nitrogen, phosphorus, and other parameters. The data will be used to calibrate and validate two transport models (Hydrus – 1D and DSSAT CERES Maize) in order to understand how the system responds to different management practices used to achieve high corn yields. Moreover, the models will be used for simulating a wide range of management scenarios in order to identify the practices which result in the highest yields with the lowest adverse environmental effects.