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Open Access Publications from the University of California

Volume 56, Issue 4, 2002

Issue cover


Improving pumping plant efficiency does not always save energy

California’s energy crisis in 2001 resulted in a state-funded program for testing irrigation pumps and improving pumping plant efficiency, with the goal of reducing energy use in California agriculture. Yet in reality, improving pumping plant efficiency may not actually translate into savings. To reduce electrical energy use, the kilowatt-hours must decrease because of fewer kilowatts or less operating time, or both. In order to evaluate the efficiency of various energy-improving adjustments, we studied several operations at pumping plants in the San Joaquin Valley. These included adjusting impellers, repairing worn pumps, replacing mismatched pumps and using more energy-efficient motors. We found that adjusting or repairing worn pumps may actually increase energy use, unless the operating time of the pumping plant is reduced. Multiple pump tests of a pumping plant are recommended, to help evaluate possible reasons for low efficiency. Pumping plant operators should also obtain the manufacturer’s performance curves to use in the evaluation process.

Garlic in clay loam soil thrives on little irrigation

We conducted 4 years of irrigation experiments in garlic on the West Side of the San Joaquin Valley to determine appropriate irrigation frequency and cutoff dates as well as the effect of irrigation on yields for crops grown in sandy and clay loam soil. In sandy soil with the moisture content at field capacity prior to the rapid growth stage, yield was strongly dependent on applied water, and weekly irri-gation was needed for maximum yield. In clay loam, yield did not depend on applied water because the garlic plants were able to ex-tract sufficient soil moisture to offset deficit irrigation. Irrigation cutoff in both soils should occur by mid-May.

Buried drip irrigation reduces fungal disease in pistachio orchards

Alternaria late blight, a fungal disease affecting both leaves and fruit, can lower the quality of pistachios and reduce grower profit. High humidity in orchards increases the magnitude and severity of the blight infections. One cause of high orchard humidity is the evaporation of water from the soil surface, which in turn is enhanced by irrigation systems that wet the surface. In this study, we tested the use of buried drip irrigation, which reduces orchard floor wetting, to see how well it controlled the disease. When compared with a traditional flood irrigation system, the buried drip system reduced orchard humidity and dew duration and increased temperature. This significantly reduced leaf symptoms of the disease and fruit infection at harvest. Additionally, more shells split open with the buried drip method, resulting in a higher yield of marketable pistachios.

Focus groups show need for diabetes awareness education among African Americans

The UC Division of Agriculture and Natural Resources Health Promotion Workgroup assessed diabetes awareness among African Americans at risk for the disease. Workgroup members conducted focus group discussions with the target population in Los Angeles, San Bernardino, San Joaquin, San Mateo, Santa Clara and Stanislaus counties. Although obesity is considered a major risk factor for type 2 diabetes, most participants cited poor dietary patterns, rather than body weight, as the most important factor in the high rate of diabetes among African Americans. Food preferences, family pressure and lack of social support were most often mentioned as obstacles to healthful dietary changes. Many felt that not enough information about diabetes was reaching the black community and voiced the need for culturally sensitive education, delivered through community-based channels.