Long-Term Organic Zero-Tillage Challenges in the U.S. Great Plains.

Much discussion and considerable research persists on the development of organic no-till or zero-till (ZT) farming methods. A long-term study established in 2009 determined the grain yield and quality of winter wheat [Triticum aestivum L. emend. Thell.] and field pea [Pisum sativum subsp. sativum] in a continuous no-till system over a 6-yr period. Grain yields were depressed following adoption of ZT compared to conventional-till organic systems, dropping to >70% by the sixth year of continuous ZT. Grain protein and kernel or seed weight also were reduced in the continuous ZT system. Perennial and annual weed pressure was severe and increased over time under continuous ZT, even with the use of cover crops, sheep (Ovis aries) and acetic acid to suppress weeds. Results of this study indicate that continuous organic ZT when growing grain crops is not possible using current knowledge and technology.