As no-tillage and other conservation tillage practices continue to increase, it is important to have knowledge of herbicide adsorption on crop residue with regard to the potential for the herbicide to be removed from the residue and move with runoff water from the field into nearby surface waters. Previous research had compared herbicide adsorption to various residues, but it was difficult to make comparisons among these studies because the residues were from different crops or the amount of residue decomposition was different. The amount of "weathering" or "aging" of the residue at the time of herbicide treatment could alter the amount initially adsorbed and subsequent desorption by rainfall. The amount of herbicide adsorbed varied greatly among the herbicides evaluated. Of the triazine herbicides, AAtrex had the least amount adsorbed (5%) and Princep was adsorbed the most (32%) with Bladex (15%) having an intermediate amount of adsorption. The two acetochlor formulations had a similar amount of adsorption with Surpass being 57% adsorbed and Harness being 61% adsorbed. Dual (44%) and Frontier (38%) had lesser amounts adsorbed compared to Surpass and Harness. A calculated Herbicide Contamination Potential (HCP) more accurately reflected potential contamination of surface water than did herbicide adsorption.
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The work on which this report is based was supported in part by the Department of the Interior, Washington, D.C. as authorized by the Water Resources Research Act of P.L. 101-397.
The activities on which this report is based were financed in part by the Department of the Interior, U.S. Geological Survey, through the Kentucky Water Resources Research Institute.
Witt, William W., "Potential for Crop Residue to Restrict Herbicide Movement in Surface from Water Corn and Soybean Fields" (1996). KWRRI Research Reports. 12.