Kentucky State University

Poster Title

Impact of Soil Organic Matter on Pesticides Mobility in the Environment

Institution

Kentucky State University

Abstract

The extensive use of pesticides in agriculture has produced benefits that reduce pest infestations and crop loss, but also have various nontarget impacts, such as the occurrence of pesticides in groundwater and surface water used for drinking water supplies. Bioactivity, mobility and fate of pesticides in the environment depend mainly on their adsorption to soil particles. Adsorption may reduce the concentration of pesticides in the soil solution, decrease their bioavailability, increase their rates of chemical degradation by soil microorganisms, or decrease their mobility into runoff and infiltration water. EPA estimates that million tons of yard waste and sewage sludge are discarded annually in the U.S. Application of these materials to agricultural soils helps minimize landfill disposal and provides an organic amendment useful for improving soil nutrient status. The objectives of this investigation were 1) to study the impact of mixing soil with sewage sludge and yard waste compost on the adsorption of pesticide residues and 2) to study the impact of humic and fulvic acids in sludge and yard waste compost on the mobility of three pesticides (trifluralin, napropamide, and azadirachtin). Mobility of these three pesticides were tested by a reverse-phase thin layer chromatographic technique. Humic and fulvic acids were extracted from soil amended with sewage sludge and soil amended with yard waste compost and their impact on pesticide movement in soil were investigated. Results indicated that the Rf values of azadirachtin decreased as the amount of humic acid and fulvic acid in soil increased.

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Impact of Soil Organic Matter on Pesticides Mobility in the Environment

The extensive use of pesticides in agriculture has produced benefits that reduce pest infestations and crop loss, but also have various nontarget impacts, such as the occurrence of pesticides in groundwater and surface water used for drinking water supplies. Bioactivity, mobility and fate of pesticides in the environment depend mainly on their adsorption to soil particles. Adsorption may reduce the concentration of pesticides in the soil solution, decrease their bioavailability, increase their rates of chemical degradation by soil microorganisms, or decrease their mobility into runoff and infiltration water. EPA estimates that million tons of yard waste and sewage sludge are discarded annually in the U.S. Application of these materials to agricultural soils helps minimize landfill disposal and provides an organic amendment useful for improving soil nutrient status. The objectives of this investigation were 1) to study the impact of mixing soil with sewage sludge and yard waste compost on the adsorption of pesticide residues and 2) to study the impact of humic and fulvic acids in sludge and yard waste compost on the mobility of three pesticides (trifluralin, napropamide, and azadirachtin). Mobility of these three pesticides were tested by a reverse-phase thin layer chromatographic technique. Humic and fulvic acids were extracted from soil amended with sewage sludge and soil amended with yard waste compost and their impact on pesticide movement in soil were investigated. Results indicated that the Rf values of azadirachtin decreased as the amount of humic acid and fulvic acid in soil increased.