Conservation Tillage Tomato Production in California's San Joaquin Valley

Abstract

Rising fuel and labor costs and stagnant commodity prices encourage tomato growers to minimize production costs whenever possible. Reducing tillage in crop rotations typically associated with bed-preparation operations may be a means to cut costs in tomato production systems. During the past several decades, a wide range of crop production systems have been developed that minimize or eliminate tillage from crops such as corn, cotton, beans, and wheat (MWPS 2000). By reducing soil disturbance, these systems preserve surface residues, reduce soil erosion, conserve water, and may enable more diverse and intensive crop rotations in areas of limited rainfall. Collectively, these practices have been called conservation tillage (CT) systems. Historically they have been based on various production practices that maintain 30 percent or more of the soil covered by residue at the time of planting (CTIC 2004), the minimum threshold for soil erosion mitigation.In California’s Central Valley, CT approaches are receiving interest as a means to cut costs and reduce dust and diesel fuel emissions from production fields. However, very little information currently exists on using CT for processing tomato production, most likely because of the recognized need for clean bed conditions for planting, harvesting, and incorporating herbicides, as well as the lack of effective CT tomato equipment. This publication summarizes recent advances in the development of CT tomato production and describes what CT tomato systems might look like.In CT tomato systems, planting beds are not disturbed or reworked following harvest of the crop preceding tomatoes. Two common forms of CT are no-till and strip-till. In no-till, no tillage is done from the harvest of one crop until the next crop is planted; the no-till crop is seeded or transplanted directly into the unworked soil of the previous crop. In strip-till, a narrow zone of soil is cleared, and subsoil layers are loosened prior to planting. This tillage zone is typically 8 to 12 inches wide and 2 to 14 inches deep. Compared with standard tillage (ST), also known as broadcast tillage, in which the entire field is tilled, strip-till decreases both the volume of soil that is disturbed and the amount of dust that is typically generated, and it also reduces fuel, labor, and equipment costs. It provides opportunities for band application of surface-incorporated herbicides and fertilizers at different depths prior to seeding. Because only a relatively small volume of soil is tilled using strip-till, it is often also called zone or vertical tillage. To be successful, strip-till and no-till systems require special implements as well as several other key changes in a cropping system.