SYMPOSIA PAPER Published: 01 January 1993
STP25124S

The Reduction of Herbicide Leaching Using Vinyl Pyrrolidone Copolymers and Methyl Vinyl Ether Maleic Acid Ester Copolymers

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Pesticides applied to soil can be leached by runoff and/or groundwater to contaminate surface water. Most pesticide residues in surface water degrade fairly rapidly and contamination is often transitory. Groundwater is a primary source of drinking water in many rural areas. Residues in cold groundwater are only slowly degraded and are of serious public concern. The objective of this study was to reduce herbicide leaching by controlling mass flow and diffusion with polymerherbicide interactions. The effect of several vinyl pyrrolidone polymers and copolymers and methyl vinyl ether/maleic acid copolymers and derivatives on three highly leachable herbicides, selected from three different chemical families, were investigated in soil columns (8 cm high, 7 cm diameter) using candler fine sand (typic Quartzipsamment). 14C-herbicide solution with or without polymer was applied to presaturated soil columns, leached with four volumes of water (12.8 cm rainfall) and the resulting radioactivity was determined in the leachate. Several polymers decreased leaching of herbicides by 10 to 60% compared to their respective herbicide controls. In bioassay studies, herbicide (5 kg/ha) with or without polymer (5 kg/ha) was applied to repacked presaturated soil columns (120-cm high, 10-cm diameter) and leached with water (2.5 to 7.5 cm of simulated rainfall). After leaching, the columns were split vertically in half and seeded with alfalfa or ryegrass to determine the distance of herbicide leached. Bioassay results showed up to 25% reduction in leaching of herbicides with some polymers in sandy soil. Structure-activity relationships of the polymers will be discussed.

Author Information

Narayanan, KS
Singh, M
Chaudhuri, RK
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Details
Developed by Committee: E35
Pages: 57–75
DOI: 10.1520/STP25124S
ISBN-EB: 978-0-8031-5238-0
ISBN-13: 978-0-8031-1888-1