Effects of Different Roller/Crimper Designs and Rolling Speed on Rye Cover Crop Termination and Seedcotton Yield in a No-Till System

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 cereal rye (Secale cereale L.) termination rate, vibration, and seedcotton yield was tested and evaluated on two roller designs during the 2004-2005 growing season. A three-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 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 seedcotton yield differed between years: 2,150 kg ha(-1) and 2,462 kg ha(-1) in 2004 and 2005, respectively. In 2004 and 2005, no differences in seedcotton yield existed among roller types, speeds, and RoundupTM (glyphosate). In both growing seasons applying glyphosate with rolling operation did not affect seedcotton yield. Using rollers only without herbicide was effective in maintaining seedcotton yield while reducing cost of herbicide.