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Atrazine and Metolachlor Loss in Surface and Subsurface Runoff from Three Tillage Treatments in Corn
Author(s) -
Gaynor J. D.,
MacTavish D. C.,
Findlay W. I.
Publication year - 1995
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1995.00472425002400020006x
Subject(s) - surface runoff , tillage , tile drainage , atrazine , metolachlor , environmental science , loam , plough , alachlor , agronomy , conventional tillage , surface water , hydrology (agriculture) , pesticide , environmental engineering , soil science , soil water , biology , ecology , geology , geotechnical engineering
Conservation tillage with residue management has been proposed as the most effective means to reduce soil deterioration in southwestern Ontario. Two conservation tillage treatments, ridge (RT) and zero (ZT) tillage, were compared with conventional moldboard plow (CT) tillage from 1987 to 1990 for atrazine [6‐chloro‐ N ‐ethyl‐ N′ ‐(1‐methyethyl)‐1,3,5‐triazine‐2,4‐diamine], deethylatrazine [6‐chloro‐ N′ ‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine], and metolachlor [2‐chloro‐ N ‐(2‐ethyl‐6‐methylphenyl)‐ N ‐(2‐methoxy‐1‐methylethyl)acetamide] loss in surface runoff and tile discharge. Twenty‐five to 44% of the annual rainfall resulted in total field runoff (surface runoff or tile discharge). Conservation tillage increased surface runoff 42% and decreased tile discharge 15% compared with conventional tillage, but total field runoff was the same from all treatments. Runoff events shortly after herbicide application produced the greatest herbicide concentrations and losses in both surface runoff and subsurface drainage. Averaged over years, herbicide concentration in surface runoff and tile discharge was, respectively, 1.3 and 1.8 times greater from conservation than conventional tillage. Conservation tillage altered the source of herbicide loss compared with conventional tillage, but environmental factors after herbicide application were more important in determining total herbicide loss than tillage. Deethylatrazine was found in both surface runoff and tile drainage and accounted for 10 to 27% of combined atrazine and drethylatrazine loss.