Effects of recharge on the transport of agricultural chemicals at the Princeton, Minn. Management Systems Evaluation Area (MSEA), 1991-92

Rates of water movement through the unsaturated zone greatly affect the amount and concentrations of agricultural chemicals that may reach the water table. For example, recharge can flush to the water table chemicals that have accumulated In the unsaturated zone during dry periods. A better understanding of how topography influences recharge and the movement of agricultural chemicals is needed. In 1991, the U.S. Geological Survey (USGS), with funding from the USGS Toxic Substances Hydrology Program, began studying the movement of water and agricultural chemicals to the water table at the Management Systems Evaluation Area (MSEA) near Princeton, Minnesota. Instruments were installed to measure the movement of moisture through the soil beneath a corn field. Samples of the recharge water were analyzed for concentrations of agricultural chemicals and tracers. Field recharge and tracer tests were simulated In the laboratory.