Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2009
Publication Date: July 29, 2009
Citation: Kornecki, T.S., Price, A.J., Raper, R.L., Arriaga, F.J. 2009. New roller/crimper concepts for mechanical termination of cover crops in conservaton agriculture. Renewable Agriculture and Food Systems. 24(3):165-173. Interpretive Summary: Cover crops are a vital part of no-till conservation agriculture, but they must be managed appropriately not to create planting problems for producers. One technique to manage tall cover crops such as rye that produce large amounts of biomass is to roll down and crimp covers using rolling technology. Rollers/crimpers have been used by some U.S producers to manage cover crops, but large vibration generated by the original roller design limit the adoption of this technology. Six different roller designs were field tested in two operating speeds: a straight-bar roller, curved-bar roller, a smooth roller without crimping bar, a smooth roller with an oscillating crimping bar and two different cam mechanisms, and two-stage roller. In three growing seasons, two and three weeks after rolling, all tested roller design effectively terminated rye between 96% and 99% without herbicide use. This rate was above the recommended rye termination rate of 90% to plant a cash crop into rolled residue. During three years, the rolled rye residue preserved much better soil volumetric moisture content compared to standing rye even under severe drought conditions. At both speeds the original straight-bar roller design generated the highest vibration levels and exceeded comfort and health limits set by international standards. All other roller/crimper designs generated much less vibrations both on roller’s and tractor’s frames, and were below health and comfort limits, thus improving comfort to the operator. Overall, two and three weeks after rolling, all roller designs effectively terminated rye above 90% which is the recommended termination level of rye to plant a cash crop into a residue mat, while protecting soil surface from water loss and generating less vibration.
Technical Abstract: Rollers/crimpers have been used in conservation agriculture to terminate cover crops, however, excessive vibration generated by the original straight-bar roller design has delayed adoption of this technology in the United States. To avoid excessive vibration, producers generally reduce operating speeds which increases rolling time. Six roller designs were tested at 3.2 and 6.4 km/hour in field experiments in Alabama during 2006, 2007, and 2008: a straight-bar roller, curved-bar roller, a smooth roller without crimping bar, a smooth roller with an oscillating crimping bar and two different cam mechanisms, and two-stage roller. Rye termination rates were evaluated one, two, and three weeks after rolling. Soil volumetric moisture content (VMC) was also measured at the day of rolling, and then one, two, and three weeks after rolling. Vibration was measured on rollers’ and tractor’s frames during operations. In 2006 2007 and 2008 growing seasons, rye termination rates ranged from 96 to 100% and from 98 to 100%, two and three weeks after rolling, respectively. During three growing seasons, rolled rye residue preserved much better VMC compared to standing rye. VMC for standing rye was 2% (on average) lower than for rolled rye. Even under severe drought conditions in 2007, the rye mat on the soil surface slowed soil-water loss (VMC=3.7% versus 1.1% for standing rye) one week after rolling. The straight-bar roller generated the highest vibration on the tractor’s frame at 6.4 km h-1 (0.71 m sec-2, RMS), exceeding International Standards (ISO). At 6.4 km h-1, new roller designs generated significantly lower acceleration levels from 0.12 to 0.32 m sec-2 on the tractor’s frame which were below health limits classified by ISO, while maintaining or exceeding rye termination rates.