Perennial Cover Crop Strategies for Annual Vegetable Rotations.

Vegetable producers in Wisconsin are currently dealing with increased fertilizer nitrogen costs, problems with soluble nitrates leaching into the groundwater, and consumers’ demand for more environmentally sustainable practices. Cover crops within the vegetable rotation could provide nitrogen and other rotational and species specific benefits. The goal of this project was to develop perennial cover cropping systems that could be readily applied to annual vegetable rotations. Objectives were to evaluate 1) the stand establishment and persistence of cover crops in a snap bean – sweet corn rotation, and 2) potential for competitive effects of cover crops on vegetable crops. Small plot studies evaluated alfalfa, hairy vetch, red clover, sweet clover, alsike clover in comparison with annual rye. Cover crops were established under snap bean during the first phase of the crop rotation, maintained through the sweet corn phase of the rotation, and plowed down prior to potato planting in the third year. Cover crops readily established, but reduced snap bean yield and quality in 2005 and 2006 due to competitive effects and residue contamination of the harvested crop. In the second season, sweet corn yields in 0 N treatments suggested nitrogen benefit of 50 to 70% of recommended fertility rates. Sweet corn yield in 2007 was limited by early frost, but yields reflected substantial N benefit from cover crops. Biomass of red clover, alfalfa, and white clover exceeded 2 t/ha prior to frost after sweet corn harvest. This research demonstrated the potential value of using perennial cover crops within an annual vegetable rotation.