Pesticide runoff loads from lawns and golf courses

Pesticide runoff loads from grass surfaces were estimated for 29 chemicals commonly applied to U.S. lawns and golf courses. Data on pesticide properties and typical application rates and schedules were developed and summarized as input parameters for the TurfPQ runoff model. Weather data for each of 9 U.S. cities were generated by the USCLIMATE model and modified by the addition of growing season irrigation. Simulation runs were made for each chemical, grass surface (lawns, greens, fairways), and city, and the results were summarized as mean annual and 1-in-10 year annual maximum daily pesticide loads. These loads varied greatly with pesticide, grass surface, and city, ranging from 0 to 875 g/ha for mean loads and 0 to 818 g/ha for 1-in-10 year daily loads. Mean annual loads averaged over the 29 chemicals and 3 grass surfaces were found to be closely related to growing season precipitation. Variations among the nine cities were well-captured by three general climate categories: Humid, characterized by abundant precipitation and warm temperatures, represented by Atlanta and Houston; temperate, with moderate precipitation and temperature, as with Albany, Columbus, Madison, and Olympia; and dry, with sparse precipitation, represented by Bismarck, Fresno, and Roswell. Mean annual pesticide runoff was 37, 9, and 2 g/ha in the humid, temperate, and dry regions, respectively.