|Koger Iii, Clifford|
Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 7, 2004
Publication Date: August 1, 2005
Citation: Koger III, C.H., Reddy, K.N. 2005. Effects of hairy vetch (Vicia villosa) cover crop and banded herbicides on weeds, grain yield, and economic returns in corn (zea mays). Journal of Sustainable Agriculture 26(3):107-124. Interpretive Summary: Hairy vetch is a winter annual legume used as a cover crop for weed suppression in many cropping systems. Little is known, however, of the potential of the integration of hairy vetch cover crop (broadcast and band desiccated over corn-row) and PRE plus POST (broadcast, banded, and no herbicide) herbicides for reducing herbicide inputs while maintaining or improving corn yields and economic returns. Hairy vetch cover crop did not reduce total weed dry biomass compared with no hairy vetch. Desiccation of hairy vetch cover crop over the corn-row compared to broadcast desiccation did not enhance weed control, reduced corn yield, and resulted in similar to lower net returns. Regardless of the presence or absence of hairy vetch cover crop, applying PRE plus POST herbicides in a band compared to broadcast application reduced herbicide inputs by 63% while providing similar levels of weed control, corn yield, and greater net returns in one out of two years. These results are important because they show the integration of hairy vetch cover crop and herbicide systems was not beneficial, as economic returns were similar or higher for no hairy vetch compared with hairy vetch systems and weed control and economic returns were similar between band- and broadcast-applied herbicides regardless of absence or presence of hairy vetch cover crop.
Technical Abstract: A 2-yr field study was conducted during 2002-2003 on a Dundee silt loam soil, Stoneville, MS, to examine the effects of hairy vetch cover crop (HV-D, hairy vetch desiccated at corn planting; HV-B, hairy vetch desiccated in a 38-cm band over crop row at corn planting; and no hairy vetch) and PRE plus POST (broadcast, banded, and no herbicide) herbicide application on weed control, yield, and economic return in corn. Atrazine plus metolachlor were applied PRE and POST. Bentazon in 2002 and carfentrazone in 2003 were applied in mixture with atrazine plus metolachlor POST. More hairy vetch dry biomass was present in the HV-B treatment (2,941 kg/ha) than in the HV-D (1,397 kg/ha) and no hairy vetch (0 kg/ha) systems at 7 wk after planting corn. Live and desiccated hairy vetch in HV-B and HV-D treatments suppressed only one (pitted morningglory) out of five weed species evaluated. Corn yields were higher in the HV-D system when compared with no hairy vetch treatments in 2003. Corn yields were similar with band- and broadcast-applied PRE plus POST herbicides. Higher costs associated with hairy vetch were offset by higher corn yields in the HV-D system compared with no hairy vetch in 2003. Applying PRE plus POST herbicides in a band resulted in similar net returns as broadcast herbicide application. These findings indicate that hairy vetch cover crop had little effect on reducing densities of weed species studied, higher costs associated with cover crops can be negated with higher corn yields, and herbicide inputs could be reduced by applying herbicides in a band vs. broadcast without reducing corn yields or economic returns.