ENGINEERING AND GINNING Cotton Population and Yield Following Different Cover Crops and Termination Practices in an Alabama No-Till System

In Alabama, typically, a three-wk period is required after rolling down a cover crop to achieve termination rates >90%, and to eliminate competition for water between the cover crop and cash crop. Cover crop termination can be sped up by applying herbicides during the rolling process. However, for organically grown cotton, synthetic herbicides cannot be used. This experiment evaluated the effectiveness of terminating two cover crops using a roller/crimper alone and with glyphosate, or two organic herbicides at different application rates to determine the effects of cover crop termination practices on cotton population and yield. In the three growing seasons, rye termination rates were between 99% and 100% for all rolling treatments three wk after rolling. Similar rates were generated for crimson clover but only in 2011, as crimson clover termination rates in two yr were lower. Organic herbicides did not increase cover crop termination compared with glyphosate and roller alone. In 2009 there was no difference in cotton population following rye and crimson clover. In 2010, cotton population following clover was higher than with cereal rye, although, in 2011, cotton population following rye was higher compared to crimson clover. In three growing seasons, seed cotton yield following rye was significantly higher compared to crimson clover. In 2010, rainfall deficit and high temperatures negatively impacted cotton growth and substantially reduced yields compared to 2009. Overall, rolling treatments did not affect cotton population and yield. In contrast, cotton population and yield were affected by different weather conditions during 2009, 2010, and 2011 growing seasons.