Organic Mulch Reduces Pesticide Runoff
							Growing vegetables with an organic mulch, hairy vetch - a legume - instead of plastic mulch, reduced pesticide losses by as much as 90% in experiments in Maryland. The vetch also greatly reduced water runoff and sediment losses. This is the first demonstration of the tactic’s effect on pesticide loss. Results of the research were presented at a meeting of the American Chemical Society in New Orleans. The Chesapeake Bay and its aquatic organisms have long been threatened by polluted runoff from farms, lawns, golf courses, streets, septic tanks and other sources. And on the Bay’s Delmarva Peninsula, runoff from vegetable fields may contribute to endangering shellfish such as shrimp, clams and oysters. The new findings point to ways to reduce this threat. Polyethylene mulch is used to conserve soil moisture and control weeds on about 4,600 acres of tomato and floral crops in Northhampton and Accomack counties that make up Virginia’s eastern shore. Runoff increases, however, because plastic covers 50% to 75% of the fields. Pesticides that aren’t absorbed into the soil can be removed easily from the plastic surface by rain. In a three-year collaborative study, ARS chemist Cathleen Hapeman and her co-workers grew tomato plants in both plastic-covered and hairy vetch mulch plots at the agency’s Beltsville, Md., Agricultural Research Center. They measured the runoff and its sediment and pesticide concentrations. Compared to the plastic-covered plots, the vetch-mulch plots lost about two to 10 times less water, 10 times less soil and on average, 10 times less pesticide. Scientists tested some runoff from the plots on clams and other bottom-feeding organisms that serve as indicators of water quality. Preliminary results of the tests, conducted at the University of Maryland’s Chesapeake Biological Laboratory in Solomons, Md., showed that runoff from polyethylene plots can harm the aquatic organisms. The organisms were less affected by runoff from plots mulched with hairy vetch.
					Copyright, Great American Publishing, The Vegetable Growers News 343 South Union Street - PO Box 128 Sparta, Michigan 49345 616-887-9008 | fax 616-887-2666 | email