Submitted to: Annual Southern Conservation Tillage Conference for Sustainable Agriculture
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2013
Publication Date: 5/13/2013
Citation: Kornecki, T.S., Price, A.J., Balkcom, K.S. 2013. Cotton population and yield following rye and crimson clover termination with roller/crimper and herbicides in an Alabama no-till system. In: Iversen, K.V. Proceedings of the 33rd Southern Conservation Agricultural Systems Conference. Available at: http://www.ag.auburn.edu/auxiliary/nsdl/scasc/.
Technical Abstract: Cover crops are an essential part of no-till systems because of important benefits such as improved soil quality, weed control and moisture conservation. Typically, under optimal weather conditions, a three week time period, after rolling, is required to achieve termination rates above 90%. A common method to enhance the cover crop termination process and keep recommended cash crop planting dates is to apply a herbicide with rolling. However, synthetic herbicides cannot be used in organic systems, thus organic herbicides may be applied. The objectives were to determine the effectiveness of terminating rye and crimson clover utilizing an experimental two-stage roller and three types and application rates of herbicides on cover crop termination rates, cotton population and yield during the 2009 and 2010 in Alabama. Each herbicide glyphosate, Weed-Zap and vinegar 20% acidity was applied as a continuous spray, every second and every third crimp through a high speed nozzle system. Termination rates were assessed at rolling and one, two, and three weeks after rolling. In 2009, rye produced 8,400 lbs/ac and crimson clover generated 5,900 lbs/ac (dry basis). In 2010, biomass for both cover crops was substantially lower (3,500 lbs/ac for rye and 3,100 lbs/ac for crimson clover) due to below freezing temperatures and excess precipitation in January. Rye termination rates were above 95% for all rolling treatments three weeks after rolling. In both years applying glyphosate with rolling helped to increase rye termination near 100% two weeks after rolling. In contrast, organic herbicides did not increase cover crop termination compared to roller alone. In 2009, three weeks after rolling, termination rates for crimson clover were lower (80%) due to higher soil available moisture. The termination process can be faster with continuous or reduced supplemental applications of glyphosate (up to 42% reduction) but not with organic herbicides. In 2009 cotton population following rye and crimson clover was the same (41,000 plants/ac). In contrast, in 2010 cotton population following rye was significantly lower (24,000 plants/ac) compared to crimson clover (42,000 plants/ac) and might be associated with limited soil coverage due to reduced biomass, high temperature, and a lack of rainfall. Cotton yield following rye was higher and produced more bolls compared to crimson clover. This difference could be attributed to nitrogen released by crimson clover that promoted vegetative growth (taller plants). In 2009, seed cotton yields were 3,100 lbs./ac, and 2,500 lbs/ac, following rye and crimson clover, respectively. In 2010, a rainfall deficit and high temperatures negatively impacted cotton yield and substantially reduced yields (1,600 lbs/ac following rye and 1,450 lbs/ac following crimson clover).