INFLUENCE OF BUFFERS ON PESTICIDE AND NUTRIENT RUNOFF FROM BERMUDAGRASS TURF

Buffer length (0, 2.4, and 4.9 m), mowing height (1.3 and 3.8 cm), and solid-tine aerification were evaluated to reduce pesticide and nutrie nt runoff from bermudagrass [Cynodon dactylon (L.) Pers.] turf on a Ki rkland silt loam (fine, mixed, thermic Udertic Paleustolls) with a 6% slope. Nitrogen, P, chlorpyrifos [o,o-diethyl o-(3,5,6-trichloro-2-pyr idinyl) phosphorothioate], and the dimethylamine salts of 2,4-D (2,4-d ichlorophenoxyacetic acid), mecoprop [2-(2-methyl-4-chlorophenoxy) pro pionic acid], and dicamba (3,6-dichloro-o-anisic acid) were applied at standard use rates on plots Located upslope of buffers. A portable ra infall simulator applied precipitation rates of 51 or 64 mm h(-1) for 75 to 140 min within 24 h after chemical application. Soil moisture be fore simulated rainfall in July 1995 was low and pesticide and nutrien t loss to surface runoff was < 3% and 2% of applied, respectively. Hig hest concentrations of pesticides and nutrients in runoff water were 3 14 mu g L-1 for 2,4-D and 9.57 mg L-1 for PO4-P from the treatment con taining no buffer. In August, 165 mm of natural rainfall fell 7 d befo re simulated rainfall and pesticide and nutrient loss to surface runof f was increased to 15 and 10% of applied, respectively. Highest concen trations of pesticides and nutrients in runoff water were 174 mu g L-1 for 2,4-D and 8.14 mg L-1 for PO4-P from the treatment containing no buffer. Overall, buffers were effective in reducing pesticide and nutr ient runoff due in part to dilution. In most instances, buffer mowing height, length (2.4 vs. 4.9 m), and aerification did not significantly affect pesticide and nutrient runoff.