Roller type and operating speed effects on rye termination rates, soil moisture, and yield of sweet corn in a no-till system

A field experiment was conducted in Cullman, AL, to evaluate the effects of three different rollers/crimpers on the termination of a rye (Secale cereale L) winter cover crop, soil moisture, and yield of sweet corn (Zea mays saccharata L.) in a no-till system. The following roller types were tested: a straight bar roller, a smooth roller with crimper, and a two-stage roller. These rollers were tested at operating speeds of 3.2 km·h−1 and 6.4 km·h−1. The three rollers/crimpers were compared with a smooth drum roller (no crimping bars) plus glyphosate applied at rate 1.0 kg·ha−1 used as a control. Rye termination dates were selected to be 3 weeks before the recommended sweet corn planting date, which is in the beginning of May for this region. Data indicate that at 3 weeks after rolling for all seasons (2006–2008), 100% rye termination was reached with the smooth drum roller and glyphosate. Two weeks after rolling, average rye termination rates by rollers/crimpers alone were 54.6%, 30.0%, and 50.4% in 2006, 2007, and 2008, respectively. Three weeks after rolling, rye termination rates increased only by approximately equal to 10% compared with 2 weeks after rolling. These termination levels were below the recommended rate of 90% termination necessary for planting a cash crop into the cover residue. Lower rye termination was probably caused by rolling the rye in an early growth stage (flowering stage). The rollers’ operating speed did not influence rye termination rates. Similarly, roller type did not affect soil moisture during the first and second week after rolling. Applying glyphosate with rolling did not increase yield of sweet corn in any of the three growing seasons, and in 2006, sweet corn yield was lower compared with the roller alone treatments. These results are important to vegetable organic systems, in which use of herbicides is not allowed. No significant difference in sweet corn yield was found between operating speeds of 3.2 km·h−1 vs. 6.4 km·h−1 and between the assigned treatments in all growing seasons. However, significant differences in sweet corn yield were detected between the years, most likely as a result of different weather patterns. The lowest sweet corn yield of 3513 kg·ha−1 was reported in 2007 as a result of severe drought in spring and summer of 2007. The highest yield of 15,613 kg·ha−1 was recorded in 2006. In 2008, the yield was 10,158 kg·ha−1. Although the different roller designs were not as effective in ending the rye cover crop compared with the glyphosate treatment, sweet corn yields were unaffected. Multiple rolling operations over the same area could be useful if greater rye termination levels are required without the use of a herbicide, but this recommendation should be tested experimentally in more detail.