Mechanical Versus Herbicidal Strategies for Killing a Hairy Vetch Cover Crop and Controlling Weeds in Minimum-Tillage Corn Production

Reducing tillage and eliminating herbicide use are good sustainable agriculture practices but present challenges. The benefits and drawbacks of using mechanical vs. herbicidal methods to kill hairy vetch pre-plant cover crops and control post-emergence weeds were studied. Pre-plant treatments tested were 2,4-D plus residual herbicides, 2,4-D alone, flail mower, corn stalk chopper, light disk, and heavy disk. The pre-plant herbicide treatments were followed by post-emergence dicamba application, while pre-plant mechanical treatments were followed by post-emergence cultivation as needed for weed control. Pre-plant and post-emergent herbicide use controlled broadleaf weeds. Pre-plant mechanical treatments plus cultivation did not control broadleaf weeds as well as herbicides did, but weed levels were kept below a designated threshold in two of four experiments. Mechanical treatments that left vetch on the surface reduced initial weed growth compared with heavy disking that incorporated residue. Cultivation following chopping or light disking was less efficient at reducing weed populations than cultivation following heavy disking was. Reduced tillage maintained surface residues and reduced weed emergence, but also reduced cultivation efficiency, leading to similar final weed populations in all mechanical treatments.