ARS | Publication request: A rotational framework to reduce weed density in organic systems

Submitted to: Renewable Agriculture and Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 16, 2010
Publication Date: January 23, 2011
Citation: Anderson, R.L. 2011. A rotational framework to reduce weed density in organic systems. Renewable Agriculture and Food System. 25:189-195.

Interpretive Summary: Organic farmers invest considerable resources to reduce the impact of weeds. In conventional cropping systems, producers have reduced weed density in their croplands by developing population-based weed management. This approach integrates cultural tactics that disrupt weed population growth with control tactics (primarily herbicides). Producers have reduced herbicide use 50% with population-based management. In this paper, we suggest ways for organic producers to use this approach in reducing weeds in their systems also. A key tactic will be rotation design. We suggest a nine-year rotation that includes alfalfa, corn, soybean, winter wheat, and a forage mix of oat/dry pea. The crop arrangement will suppress weed population growth and accrue additional benefits to improve organic production.

Technical Abstract: Weeds are a major obstacle to successful crop production in organic farming. Producers may be able to reduce inputs for weed management by designing rotations to disrupt population dynamics of weeds. Population-based management in conventional farming has reduced herbicide use 50% because weed density declines in cropland across time. In this paper, we suggest a nine-year rotation comprised of perennial forages and annual crops that will disrupt weed population growth and reduce weed density in organic systems. Lower weed density will also improve effectiveness of weed control tactics used for an individual crop. The rotation includes three-year intervals of no-till, which will improve both weed population management and soil health. Even though this rotation has not been field tested, it provides an example of designing rotations to disrupt population dynamics of weeds. Also, producers may gain additional benefits of higher crop yield and increased nitrogen supply with this rotation design.