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Title: Integrating a complex rotation with no-till improves weed management in organic farming

item Anderson, Randal

Submitted to: Agronomy for Sustainable Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2015
Publication Date: 6/29/2015
Citation: Anderson, R.L. 2015. Integrating a complex rotation with no-till improves weed management in organic farming. Agronomy for Sustainable Development. 35:967-974.

Interpretive Summary: Organic producers are interested in no-till systems, but they are concerned about controlling weeds without tillage. A complex rotation integrated with no-till disrupts weed population dynamics such that producers may be able to no-till in organic farming. The rotation includes both perennial and annual crops, with sequencing involving a 9-year interval. Both annual and perennial weeds are suppressed with this systems approach. This approach well enable producers to include perennial forage crops in the rotation to further enhance the suppression of weeds as well as provide biological N for annual crop growth. A no-till system will help organic producers restore and preserve the health of their soils.

Technical Abstract: No-till practices are restoring and protecting soil health, and are considered critical for achieving sustainability of global agriculture. Organic producers in the United States would like to no-till, but are concerned about managing weeds without tillage. In conventional agriculture, no-till improves weed management in diverse rotations when crops are arranged in 2-year intervals of cool-season and warm-season crops. A similar approach with organic rotations may enable producers to also accrue the weed management benefit of no-till in organic farming along with restoring soil health. The complex rotation included 3 years of a perennial legume and 6 years of annual crops arranged in 2-year intervals of warm-season or cool-season crops. The no-till, complex rotation can 1) reduce weed emergence 3- to 4-fold in some annual crops; 2) delay weed emergence 2 to 4 weeks; 3) reduce yield loss due to weed interference; 4) suppress invasion of dandelion into cropland; and 5) enhance soil restoration, improve nutrient cycling, and increase soil porosity. Furthermore, perennial red clover can be converted to no-till cropland with fall mowing, thus organic producers can include a perennial legume in a no-till rotation. The complex rotation increases the impact of no-till on weed seed decay in soil and provide numerous opportunities for cover crops to replace tillage for controlling weeds. These benefits suppress weed growth and interference such that organic producers may be able to continuously no-till in their farming systems, thus accruing restoration of soil health and long-term sustainability gained with no-till.