Research on Large California Farm Proves Organic Transition Feasible

Flexible management techniques and careful planning helped large-scale central California vegetable farmers participating in a SARE-funded University of California-Davis research project convert to organic production, demonstrating that well-thought-out transitions can be accomplished successfully. Most of the anticipated problems were carefully controlled and, in contrast to many other transition experiments, the organic fields performed as well as the conventional ones.

Tanimura and Antle Inc. converted over 200 acres of their Salinas Valley intensive lettuce, broccoli, spinach, and celery production into 1- to 5-acre parcels of organic production of diverse crops such as specialty greens, leaf lettuce, and herbs. Then researchers took their success to a wider audience of growers, farm consultants, Extension, and other agencies.

The outreach focused on how UC researchers, the farmers, and farm advisers teamed up to develop the experimental design and identify potential problems. Expecting weeds, pests, and soil fertility to be major constraints, researchers monitored changes in the field and provided continuous feedback to the growers. The growers, in turn, adapted their strategies to compensate, in one instance switching from legume cover crops to rye and mustard because weeds became problematic with the legumes.

“What they did was biodiversity based,” said Louise Jackson, UC-Davis extension specialist and project leader. “They planned species mixes and cropping patterns and managed fertility well. They used good organic strategies.”

Frequent hand hoeing kept purslane and groundsel in check, while less susceptible crop varieties and organic pest control reduced impacts of aphids and leaf miners. The growers shifted planting dates to avoid pest problems. They developed a reuseable drip line for irrigation to deliver soluble organic fertilizers, which not only conserved water and cut costs, but also kept the surrounding soil much drier, reducing incidences of weeds and diseases.

Jackson talked to hundreds of people about the project throughout Central California at grower meetings, workshops, field days, and short courses, emphasizing their whole-farm research as a new approach to analyzing organic systems.

Their biggest worry—that the organic fields, set in the middle of a non-organic environment, were going to become oases for large populations of nearby pests—never materialized. “Organic farms are generally on the periphery where they are isolated by grasslands or other ecosystems,” Jackson said, “but this tells me that organic transition is possible in the midst of a conventional growing environment.”

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