Winter Legume Cover Crops for Cotton: Field Experiences with Crimson Clover and Hairy Vetch

Planting wheat cover crop in row middles is a common practice for ridge-till cotton production on the Malden Ridge in Southeast Missouri and Northeast Arkansas. Cover crops help provide wind protection to cotton seedlings and minimize injury from blowing sand. However, wheat may not be the most suitable cover crop in every situation. It is a possibility that leguminous species such as crimson clover and hairy vetch could be substituted in place of wheat in row middles for a cover crop in cotton. These leguminous species also fix their own nitrogen, which can serve as an excellent “green manure” for the cotton crop, also reducing nitrogen inputs. Experiments have been conducted at the University of Missouri Rhodes Farm in Clarkton, MO to determine the effectiveness of crimson clover and hairy vetch as a cover crop in cotton. Beginning in 2006, we compared crimson clover to spring oats and winter wheat as a cover crop for cotton fertilized at 0, 40, 80, or 120 lb N/ac. Yields were highest for each cotton crop at 40 lb N/ac, regardless of cover crop. No significant differences in yield were found between cover crops. In 2009, a study was conducted comparing cotton crops with either wheat as a cover at 100 lb N/ac or hairy vetch at 40 lb N/ac. Tissue nitrate levels at first bloom from winter wheat treatments measured 22,700 ppm compared to 20,900 ppm from hairy vetch treatments. Both treatments remained in the critical nitrate range for first bloom while vetch plots received 60 lb N/ac less nitrogen.