The goal of this project is to demonstrate effects of diverse organic strawberry/vegetable rotations and integrated ecological practices on agroecosystem health.
In 2001, we initiated a replicated on-farm trial at Moss Landing, California with number of years between strawberry crops as the main plot treatment (5 levels) and strawberry cultivar as sub-plots (2 levels). Ecological practices such as biofumigation with broccoli residues and mustard incorporation, compost application, use of vegetables that do not host Verticillium dahliae (spinach and broccoli) as rotational crops, and choosing strawberry cultivars that are less sensitive to disease are used in an integrated manner. While the main treatment effects will be tested after the fifth year, soil health indicators (Verticillium dahliae propagule number, soil inorganic N, and other physicochemical indicators) and agroecosystem health indicators (yield, disease incidence, and nutrient budgets) will be monitored during all five years.
In the first three years, strawberries, vegetables and cover crops had moderate yields and no major disease problems. No significant differences were found between any treatments in yields of any crops during the period.
The N monitoring in organic strawberries suggested:
The maximum N-loss during the rainy season reached 214 kg ha-1, and
Pre-plant plastic mulch application and adjusting basal/supplemental N rates can significantly reduce N-loss during the rainy season while maintaining fruit yield.
Broccoli residue incorporations consistently reduced Verticillium dahliae propagule number in soils, whereas mustard incorporations did not. Further a major weed (Capsella bursa-pastoris) of the plot hosts Verticillium dahliae, suggesting weed management should be integrated with soil-borne disease management.