REDUCED TILLAGE PRODUCTION SYSTEM ALTERNATIVES FOR PROCESSING TOMATOES AND COTTON IN CALIFORNIA´S SAN JOAQUIN VALLEY

Less than 1% of row crop acreage in California is currently farmed using conservation tillage (CT) practices. Adoption of CT systems in California has, however, increasingly been seen as a potential means for improving profitability, reducing energy use, and sustaining resources. Several studies are currently underway throughout the state to explore cropping system options for reducing tillage. In the fall of 1999, we established a 3.2 hectare field experiment comparing conservation and standard (ST) tomato and cotton production systems with and without winter cover crops in Five Points, CA. To date, this work has demonstrated that planting and harvesting these crops with CT systems is possible given some equipment modifications and that yields can be maintained relatively close to those of standard tillage in CT crop residue environments. Data from the second year of this study indicate that tomato yields in the CT ± cover crop systems were similar to those in the ST plots, with an elimination of 3 to 4 tillage operations following the preceding year’s cotton crop in the CT plots relative to the standard till systems. This study is the first of its kind in California to systematically compare tillage system alternatives through a crop rotation. Longer-term implications of these reduced till regimes in terms of soil compaction, water use, profitability, soil carbon sequestration, insect, weed and disease pests are being evaluated as the study progresses through an eight-year cycle.