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Herbicide leaching under tilled and no-tillage fields
- The effect of no-tillage practices on water quality exiting the root zone of deep, well-drained fields is largely unknown. This project was initiated to determine herbicide leaching characteristics as influenced by tillage practice and herbicide formulation. The research site consisted of four adjacent (0.25-ha) fields, two fields each dedicated to either tilled or no-tillage management. One field in each tillage regime received a controlled-release formulation 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, starch encapsulated], while the others received standard herbicide formulations of atrazine and alachlor. Both herbicide formulations were annually applied at the same rate: 1.7 kg ha-1 for atrazine and 2.8 kg ha-1 for alachlor. Atrazine, deethylatrazine [DEAT; 6-chloro-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine], alachlor, and Br-1 concentrations were monitored with 12 suction lysimeters (six each at 1.5- and 1.8-m depths) in each field. Alachlor was detected in <3% of all samples collected, regardless of tillage practice or herbicide formulation, while atrazine was detected in >41% of the samples. Under no-tillage, atrazine was detected in <28% of the samples with <13% exceeding the U.S. Environmental Protection Agency Health Advisor level of 3 micrograms L-1 atrazine. Under tilled conditions, 53% of the samples contained atrazine, with 35% exceeding 3 micrograms L-1 atrazine. Averaged atrazine metabolite concentration of DEAT under no-tillage was 0.52 micrograms L-1 vs. 0.39 micrograms L-1 for tilled fields. Similar Br- transport between tillage practices and reduced atrazine levels under no-tillage fields suggest that no-tillage management, on deep well-drained soils, can have a positive impact on groundwater quality.
Gish, T.J. , Shirmohammadi, A. , Vyravipillai, R. , Wienhold, B.J. , Soil Science Society of America.
atrazine , alachlor , losses from soil , adsorption , degradation , leaching , no-tillage , tillage , drained conditions , groundwater , water quality , Maryland
- Includes references
- Soil Science Society of America journal May/June 1995. v. 59 (3)
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.