Matrix-Based Fertilizers Reduce Pesticide Leaching in Soil

Abstract

The presence of pesticides in groundwater has been documented in several large-scale studies and numerous small-scale investigations. Pesticide leaching through soil has been identified as a major cause for the occurrence of these chemicals in surface and groundwater. We developed matrix-based fertil- izers (MBFs) that have been shown to reduce N and P leaching. We tested the efficacy of the ionic bonds in the MBFs to reduce 2,4-dichlorophenoxyacetic acid (2,4-D), metolachlor, thiophanate methyl, carbaryl, diazinon, and malathion leaching in soil columns. After 7 days 2,4-D, thiophanate methyl, carbaryl, and malathion did not leach in sufficient quantities to determine if the MBF fertilizers reduced leaching compared with the control and the slow-release fertilizer Polyon®. The MBF fertilizers leached from five to 30 times less metolachlor than the control and Polyon® treatment. Treatments with MBF fertilizers leached from two to 72 times less diazinon than the control treatment. The MBF fertilizer treatment leached from eight to 268 less diazinon than columns receiving Polyon®. The MBF formulations allow compounds with both anionic and cationic charges to bind with the Al(SO4)3 3H2O and/or Fe2(SO4)3 3H2O-lignin-cellulose matrix. When pesticides are added to the soil amended with matrix-based fertil- izers, the ion exchange matrix will likely bind the metolachlor and diazinon to the Al(SO4)3 3H2O and/ or Fe2(SO4)3 3H2O-starch-cellulose-lignin matrix thereby substantially reducing leaching. The MBFs could be used to limit both nutrients and pesticide leaching from agricultural fields.