SOIL AND CROP MANAGEMENT SYSTEMS FOR IMPROVED NATURAL RESOURCE QUALITY AND EFFICIENCY
Location: North Central Agricultural Research Laboratory
Title: Organic zero-till in the northern Great Plains: opportunities and obstacles
Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 29, 2011
Publication Date: November 16, 2011
Citation: Carr, P.M., Anderson, R.L., Lawley, Y.E., Miller, P.R., Zwinger, S.R. 2011. Organic zero-till in the northern Great Plains: opportunities and obstacles. Renewable Agriculture and Food Systems. 27:12-20.
Interpretive Summary: A major difficulty with organic farming is the use of extensive tillage to control weeds. Organic producers are concerned about the impact of tillage on soil health and long-term sustainability of their farming approach. One possible alternative is using vegetative mulch (cover crops) to suppress weeds; the cover crop is killed with a roller-crimper, an implement that does not require tillage. Control efficacy of this implement, however, has been inconsistent. Scientists are expanding their research perspective to compare cropping system designs along with in-season weed control measures. No-till organic farming may be possible with rotations comprised of a wide diversity of crops and use of novel weed control implements.
The use of killed cover crop mulch for weed suppression has been demonstrated in organic no-till or zero-till farming systems in eastern U.S. regions and in Canada. Implements have been developed to make this system possible by terminating cover crops mechanically with little if any soil disturbance. Ongoing research in the U.S. northern Great Plains is being conducted to identify cover crop species and termination methods for use in organic zero-till (OZ) systems that are adapted to the crop rotations and climate of this semiarid region. Several obstacles must be overcome before the use of killed cover crop mulch can be promoted as a weed control alternative to tillage in organic farming systems in the U.S. northern Great Plains. In particular, cover crop termination methods must be improved so that cover crop species are killed consistently and early enough in the growing season so that subsequent cash crops can be grown and harvested successfully. Even when these problems are solved, use of vegetative mulch produced by killed cover crops will not be a panacea for the weed control challenges faced by organic growers. Rather, cover crop mulches must be used along with crop rotation, novel grazing strategies, the judicious use of high-residue cultivation equipment, and perhaps the use of approved herbicides with systemic activity in some instances, to provide organic farmers with new opportunities to practice conservation tillage.