Soil Management Practices for Mitigation of Herbicide Residues in Runoff andInfiltration Water

Contamination of surface and groundwater by pesticides is of great concern. Application of pesticides to agricultural field may result in their transport into surface waters via runoff or into groundwater through infiltration. New soil management practices are needed to develop and expand our knowledge and technical means of agricultural production related to the fate and transport of pesticides. The objective of this study was to trace the mobility of two herbicides (trifluralin and napropamide), that are commonly used in crop protection, in runoff and infiltration water from soil treated with three management practices. A field study was conducted on a 10% land slope at Kentucky State University Research Farm. Eighteen plots of 22 × 3.7 m each were separated using metal borders and the soil in six plots was mixed with sewage sludge, six plots were mixed with yard waste compost, and six unamended plots were used for comparison. During a subsequent 3-year study, plots were planted with potato (year 1), pepper (year 2), and broccoli (year 3). Once the soil was sprayed with trifluralin and napropamide, runoff and infiltration water were collected following natural rainfalls and the herbicide residues were quantified. Addition of sewage sludge increased soil organic matter and retention of trifluralin and napropamide, lowering their concentration in runoff, and reducing their transport into streams and rivers.