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Effect of starch encapsulation and temperature on volatilization of atrazine and alachlor
- Volatilization of agricultural chemicals is one process whereby chemicals may enter into parts of the environment where they were not intended. Starch encapsulation of pesticides has been proposed as a way of modifying pesticide behavior in the soil environment. This study was conducted to assess how starch encapsulation and temperature affect volatilization of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] and alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide]. Volatilization was measured using agroecosystem chambers as model systems. Herbicides were applied at rates of 1.7 kg ha-1 for atrazine and 2.8 kg ha-1 for alachlor, as either a commercial formulation or a starch encapsulated formulation, to the surface of moist soils maintained at temperatures of 15, 25 and 35 degrees C. Air was drawn through the chambers (2.5 ml min-1) and herbicide in the vapor phase was trapped in polyurethane foam plugs. Volatilization of both herbicides increased as temperature increased. Volatilization of atrazine was less when applied as starch-encapsulated formulation than the commercial formulation. After 35 d cumulative volatilization of atrazine ranged from < 1% of that applied as starch-encapsulated formulation at 15 degrees C, to 14% of that applied as the commercial formulation at 35 degrees C. Cumulative volatilization of alachlor was greater when applied as starch-encapsulated formulation than as the commercial formulation. After 35 d, cumulative volatilization of alachlor ranged from > 2% of that applied as either formulation at 15 degrees C to 32% of that applied as starch encapsulated formulation at 35 degrees C. Differences in volatilization behavior between these herbicides are likely to be due to differences in chemical properties of these herbicides.
Wienhold, B.J. , Sadeghi, A.M. , Gish, T.J.
atrazine , alachlor , volatilization , encapsulation , starch , soil temperature , losses from soil , physicochemical properties
- Includes references.
- Journal of environmental quality Jan/Mar 1993. v. 22 (1)
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.