Cross-Disciplinary Analysis of the On-Farm Transition from Conventional to Organic Vegetable Production

Summary

This farm-scale analysis of the three-year transition to organic from conventional vegetable production tracked the changes in crop, soil, pest and management on two ranches (40 and 47 ha) in the Salinas Valley, California. Many small plantings of a diverse set of cash crop and cover crop species were used, as compared to only a few species in large monocultures in conventional production. The general trends with time were: increase in soil biological indicators, low soil nitrate pools, adequate crop nutrients, minor disease and weed problems, and sporadic mild insect damage. Some crops and cultivars consistently produced higher yields than others, relative to the maximum yield for a given crop. Differences in insect and disease damage were also observed. These results support the value of initially using a biodiverse set of taxa to reduce risk, then later choosing the best-suited varieties for optimal production. The grower used some principles of organic farming (e.g., crop diversity, crop rotation, and organic matter management), but also relied on substitution-based management, such as fertigation with soluble nutrients, initially heavy applications of organic pesticides, and use of inputs derived from off-farm sources. The organic transition was conducive to both production goals and environmental quality.