Abstract
In recent years, cover crop use in no-till organic production systems has steadily increased. Unincorporated cover crop residue forms a mulch layer on the soil surface that protects against erosion, runoff, soil compaction, and weed pressure, while conserving soil water. These covers must be managed and terminated appropriately to prevent planting problems. Field experiments (2014 and 2015) evaluated two equipment prototypes at 1.0 and 2.2 km/h to terminate cereal rye and crimson clover (legume) cover crops in small conservation farm settings; both were walk behind tractor devices. The first was a PTO driven powered roller/crimper (roller), and the second used heat from engine exhaust via a steel tube (477 K) and from electric heat strips (733 K) powered by an on-board generator to flatten and terminate cover crops. Treatments applied to mature cover crops were: exhaust heat (with or without supplemental heat strips); exhaust heat (with or without supplemental heat strips) combined with the roller; and roller only. Termination data and volumetric soil moisture content (VMC) were collected weekly for three weeks after termination.
Results were compared to untreated cover crops (control). During the two year experiment, average rye termination rates were significantly higher (93 to 97%) for the combination of exhaust heat with supplemental heat strips and the roller at both speeds compared to engine exhaust heat only, exhaust heat with heat strips, and the roller alone (87 to 92%). Standing (untreated) rye had a termination rate of 59%. Similarly, the higher average termination rates for crimson clover were observed for the combination of roller and exhaust heat with supplemental heat strips at two speeds (70 to 74%) compared to exhaust with supplemental heat strips only at two speeds (66 to 69%). The control for crimson clover was 33%. Plots with flattened cereal rye residue had higher VMC than the control in 2014 (all 3 weeks of evaluation) and in 2015 (first week of evaluation only), indicating better soil water conservation. For crimson clover (except for two weeks after rolling in 2015), no difference in VMC between flattened residue and untreated (standing clover) was observed possibly due to denser soil coverage by standing clover compared to greater spacing between stems of standing cereal rye. Overall, findings from this two years field study indicate that combining the roller/crimper and exhaust heat with supplemental heat strips is a viable alternative for organic production systems where effective cover crop termination (without commercial herbicides) is essential for cash crop growth and optimal yields.
