Title: Agrichemical Transport and Controlling Processes in the Claiborne Aquifer Recharge Area

Cooperators: D.D. Bosch, C.C. Truman, R.K. Hubbard, R.A. Leonard, D.W. Hicks, and L.T. West

Problem:
Testing of well samples collected throughout southwest Georgia has shown that chemicals used for agricultural production are having a negative impact on area drinking supplies. Losses of agricultural chemicals from the root zone are important relative to both crop production and environmental quality. When agrichemicals leave the root zone, they are no longer available for crop growth and protection and they may negatively impact surface or subsurface water quality. In addition, chemical losses to ground water may be very costly, both from efficiency and remediation standpoints. Transport of agrichemicals depends on rainfall amount, intensity, and duration; chemical solubility and degradation properties; soil properties; biological processes; and management practices. A scientific understanding of these processes requires complex, well-defined research which quantifies each of these factors.

Approach:
In 1988, as a response to this groundwater survey, the U.S. Geological Survey; Southeast Watershed Research Laboratory (SEWRL), U.S. Department of Agriculture, Agricultural Research Service; U.S. Environmental Protection Agency (USEPA); and University of Georgia began a cooperative study of chemical transport on an agricultural field near Plains, Ga. The research was undertaken to determine the paths water and agrichemicals followed once applied to the soil surface under normal climatic and management conditions. The approach followed was to manage the field in a manner typical for the region while quantifying the proportions of applied pesticides and fertilizers which: 1) degrade within the plant root zone, 2) run off from the soil surface, and 3) are transported below the root zone to the water table.

Results:
Our data indicate that under normal climatic conditions nutrient and pesticide transport to ground water is minimal. However, large spring thunderstorms soon after chemical application, combined with a saturated root zone can lead to ground water contamination. Thus, care must be used to properly manage the application and soil-water regime. Chemical application during periods of excess precipitation and saturated soil-water conditions should be avoided.