Conservation Tillage Systems for Organic Agriculture: Evolving Toward a Hybrid Model.

The widespread success of no-till farming in conventional farming systems involves direct seeding into previous crop residue, and relies on herbicides for weed control. Broad-spectrum herbicides, such as paraquat and glyphosate, are used to kill existing vegetation, while other residual and post-emergent herbicides are used to control weeds germinating with the crop.  Organic farming systems have traditionally used full-width tillage to kill existing vegetation and prepare a seedbed suitable for mechanical cultivation.  Although moderate success with no-till organic systems has been shown using a crimper-roller to kill a cereal rye cover crop, problems have emerged with reduced seedling emergence in cold soils, the difficulty in killing the cover crop, and nutrient and pest management.  We have worked with an integrated zone tillage system (also known as strip-tillage) that clears a narrow zone of soil, loosening subsoil layers and preparing a seedbed. The area between the tilled zones is managed using different equipment, increasing retention of cover crop residue on the soil surface while reducing total energy inputs. This hybrid tillage system combines positive aspects of conventional tillage and no-till, and facilitates the integration of precision weed and nutrient management practices.