A participatory, on-farm research project was initiated in 1992 in an effort to enhance mutual learning, knowledge, and experience of integrating cover crops into western Oregon vegetable production systems. A major goal of the project was to include growers, agribusiness representatives, governmental agency, Extension and university researchers in a collaborative learning process, emphasizing grower participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four “focus sessions” were hosted by lead farmers in different areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials.
Based on individual growers' specific experimental objectives, cover crop evaluation trials were established on ten farms. Typically on each farm, 5 to 10 cover crop species or mixtures (grain and legume) were planted in large plot strips. Twenty five different cover crop species, varieties, and mixtures were planted. Seasonal cover crop biomass and nitrogen accumulation rates were determined, with cover crop impacts on crop yields and economic returns evaluated at selected sites.