Herbicides for No-tillage Corn in Alfalfa Sod

Abstract

In rolling topography, soil and water runoff losses can be greatly reduced by conservation production systems. Alfalfa (Medicago sativa L.) is an important crop in Nebraska and other states which is often followed in the crop sequence by corn (Zea mays L.) or sorghum [Sorghum bicolor (L.) Moench]. Three years of field experiments indicated that herbicides can substitute for erosive moldboard plowing to destroy alfalfa without loss in the subsequent corn yield. Herbicides applied just prior to corn planting in the spring gave more consistent alfalfa control than those applied the preceeding fall. The most consistent treatment used for alfalfa control and supplemental annual weed control while producing maximum corn yield was 2,4-D amine [(2,4-dichlorophenoxy) acetic acid] plus dicamba (3,6-dichloro-o-anisic acid) at 1.12 and 0.28 kg/ha, respectively. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] plus propachlor (2-chloro-N-isopropylacetanilide) versus no preemergence herbicide was used for annual weed control in addition to the treatments to control alfalfa. This treatment was essential for maintaining corn yields where a non-residual or limited residual herbicide was used for alfalfa control.