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Effect of starch encapsulation and temperature on volatilization of atrazine and alachlor
- Abstract::
- 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.
- Author(s):
-
Wienhold, B.J. , Sadeghi, A.M. , Gish, T.J.
- Subject(s):
-
atrazine , alachlor , volatilization , encapsulation , starch , soil temperature , losses from soil , physicochemical properties
- Description:
- Includes references.
- Source:
- Journal of environmental quality Jan/Mar 1993. v. 22 (1)
- Language:
- English
- Year:
- 1992
- Collection:
-
Journal Articles, USDA Authors, Peer-Reviewed
- File:
-
Download [PDF]
- Rights:
- 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.
