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Open Access Publications from the University of California


California Agriculture is a quarterly peer-reviewed journal reporting research, reviews and news on California’s agricultural, natural and human resources.

Volume 60, Issue 4, 2006

Issue cover


Is lead toxicity still a risk to U.S. children?

Elevated blood-lead levels put children at risk for neurobehavioral-cognitive deficits, such as IQ deficiency, behavioral disorders and impaired hearing. We examined several factors that contribute to elevated lead levels in U.S. children to help define the extent to which lead toxicity from these sources continues to be a problem. The results of our review suggest that elevated levels of lead in paint, dust, soil, imported pottery and ceramic ware, ethnic remedies, and some imported candies continue to be areas of concern, while typical levels in food products appear to be acceptable. It is important to continue monitoring lead levels in children as well as in environmental and food sources.

Cost-benefit analysis conducted for nutrition education in California

Documenting the cost-effectiveness of nutrition education programs is important to justify and determine expenditures and ensure continued funding. A cost-benefit analysis was conducted using the program demographics and food-related dietary behavior of participants enrolled in California’s Expanded Food and Nutrition Education Program (EFNEP), based on methodology developed by Virginia Cooperative Extension. The initial benefit-cost ratio for nutrition education in California was 14.67 to 1.00. Several sensitivity analyses were done to estimate the effect of changes in key variables. The resulting benefit-cost ratios ranged from 3.67 to 1.00, to 8.34 to 1.00, meaning that for every $1.00 spent on nutrition education in California, between $3.67 and $8.34 is saved in health care costs. These results bolster the argument that nutrition education programs are a good investment and funding them is sound public policy.

Radiofrequency power disinfects and disinfests food, soils and wastewater

Radiofrequency (RF) is an advanced telecommunication technology first invented in the early 1900s, which is in use today for wireless communication worldwide. Because of its ability to penetrate and heat various materials, RF has the potential to disinfect and/or disinfest food, agricultural and environmental materials. However, research to validate this approach has been restricted by limited understanding of how RF photons interact with materials, and by limited access to and the high cost of its source electronics. Since the early 1990s, we have conducted research at UC Davis on continuous RF power applications using nonconventional RF systems and new operational concepts. Laboratory tests have successfully demonstrated the effectiveness of RF power to disinfect and/or disinfest fresh produce, rice, soils, agricultural wastewater, and other foods and materials. Likewise, rapid pulses of RF are lethal to arthropod pests and may provide a nonthermal disinfestation process for fresh, temperature-sensitive commodities, as well as a promising alternative to the fumigant methyl bromide.

Impact of environmental factors on fish distribution assessed in rangeland streams

We sampled fish in pools located on tributaries of Cow Creek in the northern Sacramento Valley, and related fish distribution and habitat use to environmental factors across the 2003 agricultural growing season. This rangeland watershed experiences extensive livestock use, and many landowners divert stream water for pasture irrigation. Our goal was to provide landowners and managers with current baseline information about the conditions in which fish were found. Our results provide a basis for the development and comparison of irrigation best management practices that may improve conditions for native fish in rangeland streams.

EU support reductions would benefit California tomato growers and processors

Many countries apply import barriers for processing tomatoes, but the European Union is the main producer that uses export and production subsidies. We modeled and measured the potential impacts on global markets and the California industry that would result from reductions in trade barriers (such as import tariffs) and subsidies for the European Union’s processing tomato industry. A multi-equation simulation model showed that reducing trade barriers in Europe and elsewhere (including the United States) by 50% would raise the market price for California tomatoes by about 6%, improve net returns to California processing tomato producers by $34 million per year, and improve net returns to California tomato processors by $19 million per year. We also found that a 50% reduction in EU domestic support would improve the net returns of California producers and processors by about $8.5 million per year. Based on these results, we believe that negotiating reductions in subsidies, and especially in global trade barriers, would make economic sense for the California processing tomato industry.

Weather-based yield forecasts developed for 12 California crops

Crop-yield forecasts provide useful information to growers, marketers, government agencies and other users. Yields for several crops in California are currently forecast based on field surveys and farmer interviews, although official forecasts do not exist for many crops. Because broad-scale crop yields depend largely on the weather, measurements from existing meteorological stations have the potential to provide reliable, timely and cost-effective predictions. We developed weather-based models of statewide yields for 12 major California crops and tested their accuracy using cross-validation from 1980 to 2003. Many of the weather-based forecasts were highly accurate, as judged by the percentage of yield variation explained by the forecast, the number of yields with correctly predicted direction of yield change, or the number of yields with correctly predicted extreme yields. The most successfully modeled crop was almonds, with 81% of yield variance captured by the forecast. Predictions for most crops relied on weather measurements well before harvest time, in many cases allowing longer lead times than existing procedures.