Submitted to: American Journal of Alternative Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/13/2002
Publication Date: 3/20/2003
Citation: Ashford, D.L., Reeves, D.W. 2003. Use of a mechanical roller-crimper as an alternative kill method for cover crops. American Journal of Alternative Agriculture. 18(1):37-45. Interpretive Summary: Growers are looking for cost-effective ways to manage cover crops in conservation systems. Mechanical roller-crimpers have been shown to be effective in killing cover crops in South America but roller-crimpers have not been introduced in the USA. We evaluated the use of a roller, standard herbicides (glyphosate and paraquat), and combinations of roller and reduced herbicide rates to terminate three different cover crops (rye, wheat, and black oat) at three growth stages (flag leaf, flowering, and late milk-soft dough). The roller effectively killed all three cover crops when used during late reproductive growth (late milking to soft dough stage). At an earlier growth stage (flowering), the roller in combination with half-label rates of either of the two herbicides was as effective as full label-rates of the herbicides. The roller provides additional benefits as it lays residue flat on the soil surface providing maximum soil coverage; to prevent erosion, decrease soil water losses, provide weed control, and facilitate planting. The roller alone costs about $1.51/acre to operate and the roller+herbicide (half rate) practice can reduce herbicide costs an average of $7.05/acre when killing a cover crop. This information shows it is possible to reduce the use of herbicides and implement effective alternative kill methods for cover crops.
Technical Abstract: Cover crops have long been recognized as a beneficial part of many cropping systems, however their use is still not common place. Their use may be increased by identifying more cost-effective and environment- friendly techniques for cover crop management. This study was conducted to determine the effectiveness of using a mechanical roller-crimper as an alternative kill method for cover crops. The study took place in east-central Alabama, using a split-split plot experimental design with four replications and 3 site-years in 1999-2000. Rye (Secale cereale L.), wheat (Triticum aestivum L.), and black oat (Avena strigosa Schreb.) were evaluated in terms of ease of kill and optimum time of kill using a roller-crimper, two herbicides (paraquat and glyposate) at their label rate, and two reduced chemical (half label rate) combinations with the roller-crimper. Four Feekes' scale growth stages were used to determine optimum time of kill; 8.0 (flag leaf), 10.51 (anthesis), 10.54 (early milk) and 11.2 (soft dough). Plant growth stage was the main determining factor for effectiveness of the roller-crimper. At the flag leaf stage, the roller-crimper provided only 19% kill across all covers over the 3 site-years. After plants reached anthesis, the roller-crimper with half rate herbicide combinations equaled the effectiveness of herbicides alone at their label rate, averaging 94% kill. By the soft dough growth stage, all kill methods were equally effective due to accelerating plant senescence (95% mean kill across kill methods). Use of the roller-crimper alone after anthesis can decrease costs by as much as $26.29 per ha, while providing a kill rate equivalent to that of herbicide treatment alone.