Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2011
Publication Date: 2/1/2012
Citation: Kornecki, T.S., Arriaga, F.J., Price, A.J. 2012. Roller type and operating speed effects on rye termination rates, soil moisture and yield of sweet corn in a no-till system. HortScience. 47(2):217-223.
Interpretive Summary: Organic vegetable production can be challenging since alternatives to fertilizers and for weed control are limited. Winter cover crops can be useful for organic production since they help recycle nutrients, reduce weed growth and increase water availability for the vegetable crop. However, winter cover crops should be terminated 2 to 3 weeks before vegetable planting to avoid competition. In conventional crop production, the winter cover crop is typically terminated with a herbicide application, an option not available for organic vegetable production. Rollers could be used to mechanically terminate a cover crop instead of using herbicides. The efficacy of three different roller designs for terminating a rye winter cover crop was tested in a sweet corn production system. These three rollers were compared to a winter cover terminated with a herbicide application and flattened with a smooth roller as a control. During the 3 years the study was conducted, mechanical termination methods were between 30 and 55% effective on terminating the cover crop two weeks after the operation was conducted, compared to 99 to 100% with the use of a herbicide. Termination rates three weeks after the termination operation was performed were between 30 and 66% for the mechanical methods alone. However, sweet corn yields were not affected by the winter cover crop termination method used. In fact, sweet corn yields were 24% greater with the mechanical methods compared to using a herbicide in one out of three years. Results from this study suggest that winter cover crops should be planted as early as possible in the fall, to assure that the cover crop is mature enough for optimal mechanical termination in the spring. Multiple rolling passes over the same cover crop area could speed up the desiccation of the cover crop. This research shows that rollers can be used successfully to mechanically terminate winter cover crops in organic and no-till vegetable production.
Technical Abstract: A field experiment was conducted in Cullman, Alabama 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 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 at operating speeds of 3.2 km h-1 and 6.4 km h-1. The three rollers/crimpers were compared to 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 three weeks before the recommended sweet corn planting date, which is in the beginning of May for this region. Data indicates that at three 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 10% compared to two 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 to 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 v/s 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 due to different weather patterns. The lowest sweet corn yield of 3,513 kg ha-1 was reported in 2007 due to 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 terminating the rye cover crop compared to the glyphosate treatment, sweet corn yields were not affected. If greater rye termination levels are required without the use of a herbicide, multiple rolling operations over the same area could be useful.