Skip to main content Skip to navigation
Science in action to improve the sustainability of agriculture, natural resources, and food systems
Learn More Program Areas

Cover Crops for Weed Management in Organic and Transition Systems

Grant Information

  • Project ID: 011
  • Project Status: Complete






Lawson, A. Cover crops to enhance soil productivity in organic vegetable cropping systems. MS Thesis. Dept. of Crop and Soil Sciences. 2010.

Lawson, A., A. Fortuna, C. Cogger, A. Bary, and T. Stubs. Nitrogen contribution of rye-hairy vetch cover crop blends to organically grown sweet corn. IN INTERNAL REVIEW for submission to Agronomy Journal, April 2011.

Lawson, A., C. Cogger, A. Fortuna, A. Bary, and T. Stubs. Evaluating fallcover crop blends for biomass production, residue quality, and weed suppression. IN PREPARATION for submission to J Sustainable Ag.

Website: Cover crops.

Websites from 2010 winter cover crops school. (These will be organized in to a single site, but are currently separate).


Additional Funds Leveraged

Cogger, C.G., A. Fortuna, A. Kennedy, A. Bary, K. Painter, and B. Cha. Cover crops to enhance soil productivity and nitrogen management in organic and transition vegetable production systems. WSU Emerging Research Issues. $74,528. 2007-2009. This funded a continuation of the CSANR project.

Cogger, C.G., M. Ostrom, R. Alldredge, A. Fortuna, A. Kennedy, and K. Painter. Designing production strategies for stewardship and profits on fresh-market organic farms. USDA Integrated Organic Agriculture program. $644,232. 2008-2012. CSANR grant was one of several that positioned us to receive this larger grant.

Collins, D. A, Corbin, C. Cogger, C. Benedict, and A. Bary. Selecting management practices and cover crops for reducing tillage, enhancing soil quality, and managing weeds in western Washington organic vegetable farms. $196,624. 2011-2014. CSANR grant laid the groundwork for our move into cover crops reduced tillage systems, and this is the first major grant we had funded for that work.

Burrows, C. D. Collins, A. Corbin. No-till organic vegetable production in western Washington: A Planning Proposal. USDA/NIFA Organic Research and Extension Initiative, $46,794.


We developed recommendations for seeding ratios (1:1 cereal rye: hairy vetch) and planting (mid-September) and termination (late April) dates to achieve weed management and nitrogen fertilization benefits from fall-planted cover crops under western Washington conditions. We estimated N replacement value at 50 lb N/acre under recommended management, which is less than achieved in parts of the country with an earlier onset of warm spring weather. This project allowed us to lay the groundwork to move into new research on reduced tillage cover crop systems.

Evaluation data collected from extension classes showed increased knowledge and increased interest in the use of cover crops. Specifically, cover crop workshops held in 2010 showed that one workshop was effective at increasing knowledge (>95%), and that the use of online education can be effective for both farmers (ave: 3.59 out of 5) and non-farmers (ave: 4.25 out of 5). In an evaluation of a second workshop 90% of participants indicated that they greatly increased their knowledge of summer cover crops during the workshop. Ninety-two percent indicated that they somewhat or greatly increased their skills and ability to incorporate summer cover crops. The vast majority (93%) indicated that they were very likely to use or encourage the use of cover crops as a result of the workshop.