Thatch and Soil Pesticide Degradation and Microbial Activity as Influenced by Turf Cultivation Practices

Title of Thesis: THATCH AND SOIL PESTICIDE DEGRADATION AND MICROBIAL ACTIVITY AS INFLUENCED BY TURF CULTIVATION PRACTICES Yusong Mu, Master of Science, 2009 Thesis Directed By: Mark J. Carroll, Ph.D. Associate Professor Department of Plant Science and Landscape Architecture Pesticide degradation in turf is complicated by presence of an organic matter enriched layer called thatch. It is not well understood how the extensive pesticide sorption capacity of thatch may affect the aerobic degradation of pesticides in thatch. Hollow tine cultivation and vertical mowing are two commonly used cultivation practices used to control thatch. Two studies were conducted to determine how these two cultural practices may affect microbial activity and pesticide degradation within thatch and soil. Hollow tine cultivation briefly enhanced microbial activity within thatch while vertical mowing had no consistent effect on thatch or soil microbial activity. Neither cultivation practice consistently altered the aerobic degradation of 2,4-D, flutolanil or chlorpyrifos. Thatch and soil aerobic degradation constants obtained for flutolanil and chlorpyrifos supported the hypothesis that strongly adsorbed pesticides are shielded from microbial populations that degrade pesticides within thatch.