Hairy Vetch Varieties and Bi-Cultures Influence Cover Crop Services in Strip-Tilled Sweet Corn

Hairy vetch (Vicia villosa Roth) cover crops provide a wide array of ecosystem services including erosion protection, weed suppression, and N fixation. However, adoption has been hindered by risks including overwinter mortality and regrowth following mowing or crimping. Early-flowering vetch varieties and mixed stands of vetch and cereal rye (Secale cereale L.) have the potential to reduce these risks, but little is known about their impact on N fixation. In field trials in Central Michigan, two early-flowering hairy vetch varieties (Purple Bounty and Purple Prosperity) and one later-flowering variety ('Oregon') were grown alone and in mixtures with cereal rye, prior to strip-tilled sweet corn (Zea mays L. var. rugosa). Vetches grown in mixture with rye had equal or greater overwinter survival and earlier flowering than vetches grown in monoculture. Nitrogen fixation of early-flowering varieties was not affected by mixture with rye. However, N fixation of Oregon was lower when grown in monoculture than when grown in mixture in 2009. Purple Bounty and Purple Prosperity flowered earlier than Oregon, exhibited comparable survival, and had equal or greater levels of N fixation. Despite differences in the timing of flowering, there were no differences in regrowth of hairy,etch following mowing. Nor were any differences in sweet corn yield or quality detected. These results_demonstrate that rye-vetch mixtures can increase overwinter survival, accelerate flowering, and increase N fixation relative to vetch monocultures. Observed varietal differences in flowering time, N fixation, and response to bicultures may be exploited to optimize cover crop use in agroccosystems.