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Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/1/2010 Publication Date: 2/15/2011 Citation: Kornecki, T.S., Price, A.J. 2011. Effects of different roller/crimper designs and rolling speed on rye cover crop termination and seedcotton yield in a no-till system. Journal of Cotton Science. 14:212-220. Interpretive Summary: Managing cover crops in conservation agriculture which include timely termination of cover crops using rollers/crimpers is essential to establishing optimum soil conditions before planting of cash crop. Rolling technology which was adopted from Brazil has been used in the Southern U.S. However, excessive vibration generated by the original design at higher operating speeds delay its adaptation. To address the vibration problem a new smooth roller with crimping bar concept was developed and field tested. Two rollers: the original and new smooth roller with crimping bar were compared at 2 and 4 mph in 2004 and 2005 in Alabama to determine the speed effect on rye termination, vibration levels generated by the rollers and their effects on the cotton yield. Rolling rye and applying glyphosate was also compared to rollers alone. In both growing seasons two roller designs effectively terminated the cover crop from 94% to 97% three weeks after rolling, without the need of herbicide. In addition, increase in operating speed had no effect on termination rates except the first week after rolling. In both years, increased operating speed increased vibration levels on the roller’s frame for all roller types. The smooth roller/crimper transferred two times less vibration level to the tractor’s frame than straight bar roller, and these levels are below the “very uncomfortable limit” as determined by the International Standard Organization. In both years, no differences in cotton yield were observed among roller types, operating speeds, or chemical treatment (glyphosate). Applying glyphosate with rolling rye did not affect cotton seed yield. Based on results from two growing seasons, rolling/crimping of cover crops without supplemental glyphosate application was effective in maintaining seed cotton yield while reducing cost of glyphosate. Technical Abstract: Rollers/crimpers have been utilized in no-till systems to mechanically terminate cover crops as a substitute for chemical termination; however, excessive vibration generated by the original straight bar roller adopted from Brazil has delayed its adoption in the U.S. To reduce excessive vibration, producers must decrease roller speed, which increases the time for rolling cover crops. The effect of speed on rye (Secale cereale L.) termination rate, vibration and cotton yield was tested and evaluated on two roller designs during the 2004-2005 growing season. A triple-section 4.1-m wide roller with straight bars (original straight bar roller) and a new design smooth roller with oscillating crimping bar (smooth roller/crimper) were evaluated at speeds of 3.2 and 6.4 km h-1. In 2004, higher rye termination rates resulted from the straight bar roller (96%) in comparison to the smooth roller/crimper (94%). Three weeks after rolling, both rollers had effectively terminated rye without the use of herbicides. In both seasons the smooth roller with a crimping bar transferred lower vibration levels to the tractor’s frame (at both speeds) than the straight bar roller, while maintaining rye termination rates comparable with the original design. The average cotton yield was 2150 kg ha-1 and 2462 kg ha-1 in 2004, and 2005, respectively. In 2004 and 2005, no differences in cotton yield existed among roller types, speeds, and glyphosate. In both growing seasons applying glyphosate with the rolling operation did not affect cotton yield. Using rollers only without herbicide was effective in maintaining cotton seed yield while reducing the cost of herbicide. |
