Mixed cover cropping with bellbeans (Vicia faba) and cereal rye (Avena sativa) has been used by farmers since the turn of the century for vegetable field preparation. Planting of this legume-grass mixture takes place following the harvest of the summer crop and before winter rains. The mixture is allowed to grow throughout the winter and is disked into the soil in March or early April. A vegetable crop is then planted toward the end of May. In this study, cabbage was used to demonstrate the mutual benefits that bellbeans and rye have in preparing soil for summer crops. 

Rye produces large amounts of biomass and limits weed growth by allelopathic chemical effects. Bellbeans, though they add little biomass to the system, add nitrogen by symbiotic nitrogen-fixation with Rhizobium bacteria. When rye and bellbeans are planted together, the combined effect is efficient suppression of weed growth and supply of nitrogen back to the system. Studies of soil nitrogen show that the rye/bellbean covercrop increased soil nitrogen more than bellbeans alone. This is thought to be due, in part, to the slowing of organic matter decomposition caused by mixing nitrogen-rich bellbeans with carbon-rich rye biomass on disking, facilitates nitrogen retention in the soil. 

Use Renewable Resources

Bellbeans use biological nitrogen fixation to provide nitrogen for the following crop.

Conserve Resources

Using cover crops for weed control and nitrogen fertilization reduces dependency on off-farm resources.

Manage Ecological Relationships

Cover-cropping with rye and bellbeans reestablish ecological relationships that can occur naturally on the farm instead of reducing and simplifying them.

Diversify

Mixing rye and bellbeans in a cover crop increases biodiversity during the non-crop season.

Maximize Long-Term Benefits

Using cover crops builds soil organic matter over the long term. 

Putnam, A.R., and J.S. Holt. 1983. Use of phytotoxic plant residues for selective weed control. Crop Protection. 2: 173: 181.