A kiwifruit vineyard converted to an organic farm was compared to a conventionally farmed vineyard from 1990 through 1992. February or March applications of composted chicken manure (organic plot) or NH4N O3 plus CaNH4 (NO3)3 through microsprinklers during the growing season (conventional plot) were applied to give equal rates of N. Soil analyses indicated no differences in nutrient or salt levels. Nitrogen leaf levels from the organic plot were consistently lower than those from the conventional system but were not deficient. Leaf concentrations of sodium and chloride increased over the three-year period in the organic plot, but not to phytotoxic levels. Organically grown fruit was as firm or firmer than conventionally grown fruit at harvest and four months after harvest. Damage from latania scale or omnivorous leaf roller was minimal in both plots until 1992, when the organic plot had 3.9% scale compared to 0% in the conventional plot. An economic analysis comparing the short-term profitability of the two systems will be presented.
Eliminating tillage passes is a means to reduce production costs and dust emissions in California's San Joaquin Valley tomato production region. Inserting winter cover crops between summer crops may be a way to add organic matter to the soil and thereby improve soil quality. From 1999, we evaluated conservation tillage (CT) and cover cropping (CC) in a tomato/cotton rotation in Five Points, Calif. During the course of the study, tillage operations were reduced an average of 50% in the CT system relative to the standard tillage (ST) approach. Yields in the CT no cover crop (NO) system matched or exceeded yields in the STNO system in each year. Tomato yields in the CTCC and STCC systems were comparable to the STNO except in the first year, when stand establishment and early season vigor were problems. Weed management and machine harvest efficiency in high surface residue systems are issues requiring additional work in order to make CT adoption more widespread.