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United States Department of Agriculture

Agricultural Research Service

Title: Overwinter Movement of Metolachlor in Seasonally Frozen Soils

Authors
item Sharratt, Brenton
item Sander, Kip - CIBA-GEIGY
item Tierney, Dennis - CIBA-GEIGY

Submitted to: Soil Conservation and Water Quality Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 10, 1996
Publication Date: N/A

Technical Abstract: The short growing season in the northern Corn Belt region of the United States necessitates timely planting of corn. Corn planting may be delayed, however, as a result of applying herbicides before or during planting. Applying herbicides in the fall rather than in spring may reduce the risk of delayed planting, yet little is known about the fate of fall-applied herbicides. There is a paucity of information regarding the extent to which fall-applied herbicides move within the soil profile during winter. This study evaluated the movement of fall-applied metolachlor during winter in the northern Corn Belt. Metolachlor was applied to the surface 5 cm of soil, contained in 2 m long lysimeters, in November 1994, prior to soil freezing. These lysimeters, placed in the field devoid of vegetation, were sectioned into 2 cm intervals after the soil froze to 30 cm (January) and after complete thaw in the spring (May). Soil within each section was analyzed for metolachlor using gas chromatography. No movement of metolachlor within the soil profile occurred during the fall freeze-up period (November to January). In addition, metolachlor did not move outside the zone of application during the winter (November to May). Vertical redistribution of metolachlor, however, occurred within the zone of application. Despite little downward movement of metolachlor, downward movement of water occurred during the winter. This study suggests that fall-applied metolachlor may be a viable and environmentally sound practice for corn production systems in the northern Corn Belt.

Last Modified: 9/1/2014
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