Evaluation of vegetable production management practices to reduce the ecological risk of pesticides

The ability of agricultural management practices to reduce the ecological risks of pesticides was evaluated. Risk quotients, a mathematical description of the relationship between exposure and toxicity, and hazard ratings, a rank of the potential risk of pesticides to aquatic environments, were calculated for conventional and alternative cultivation practices for tomatoes: Poly-Bare, raised beds covered with polyethylene mulch with bare-soil furrows; Poly-Rye, raised beds covered with polyethylene mulch with cereal rye (Secale cereale) grown in the furrows; and Vetch, raised beds and furrows planted with hairy vetch seed (Vicia villosa). Evaluations were conducted using measured pesticide concentrations in runoff at the edge-of-field and estimated environmental concentrations in an adjacent creek and a theoretical pond receiving the runoff. Runoff from Poly-Bare presented the greatest risk to ecosystem health and to sensitive organisms, whereas the use of Vetch minimized these risks. Previous studies have shown that harvest yields were maintained and that runoff volume, soil loss, and off-site transport of pesticides measured in runoff were reduced using the alternative management practices (Poly-Rye and Vetch). Together, these results indicate that the alternative management practices (Poly-Rye and Vetch) have a less adverse impact on the environment than the conventional management practice (Poly-Bare) while providing growers with an acceptable economic return. In addition, the present study demonstrates the need to consider the management practice when assessing the potential risks and hazards for certain pesticides.