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Open Access Publications from the University of California

Volume 74, Issue 1, 2020

Issue cover
Cover Caption: View of the Russian River near Hopland, Mendocino County. A recent UC Cooperative Extension research project in the upper Russian River and Navarro River watersheds demonstrates how water use accounting can support the development of solutions for managing limited water supplies. Photo by George Rose.

Research and Review Articles

Cover crop and mulch practices reduce agricultural pollutant loads in stormwater runoff from plastic tunnels

Macrotunnel production systems contribute over $1 billion to California's economy, but despite increased use, guidance to help macrotunnel growers limit agricultural pollutant loads in rainfall-induced runoff is sparse. Using raspberry as a model crop, we evaluated four runoff management practices during two rainy seasons of the normal 3-year raspberry production cycle: barley cover crop seeded at 500 pounds per acre, weed barrier fabric, yard waste mulch spread 2 to 3 inches thick, and polyacrylamide (PAM). Treatments were applied to 300-foot-by-6-foot-wide post rows. Barley cover crop and mulch reduced combined nitrate and nitrite nitrogen in runoff by 21% to 48% at some runoff events and reduced nitrate nitrogen in soil and leachate to groundwater by 52% to 90%. All treatments reduced turbidity and phosphorus levels in runoff and had 75% to 97% less sediment accumulation compared with bare soil. Additionally, all treatments except PAM reduced weed densities by 48% to 87% compared with bare ground, which reduced the costs of weed management. Barley cover crop had the lowest estimated costs (~$60.00 per tunnel period), while PAM and mulch were highest (~$193.00 per tunnel period).

Financial effect of limiting pesticide use near schools for almonds in nine counties depends on soils and weather

Effective Jan. 1, 2018, the California Department of Pesticide Regulation enacted a regulation regarding the use of pesticides near public K-12 schools and licensed child day care centers, including a provision that bans specific types of applications, including air-blast and air-assist, during weekday school hours (6 a.m. to 6 p.m.) to provide an additional safety margin for pesticide exposure beyond those provided by other regulations. We considered the financial effect on almond growers in nine counties, accounting for four-fifths of total almond production in 2014, if they had been unable to complete a standard spring disease management program on any buffer zone acreage. Results indicated that total annual losses for those counties if such a regulation had been in effect would have been $8.7 million, with per-acre losses ranging from 22% to over 50% of total operating costs, depending on the county. However, using a methodology that took into account historical weather and soil hydrologic group data, we estimated average annual losses in the nine counties among almond growers would have been under $0.2 million because the regulation would have affected the number of sprays completed for relatively few acres in relatively few years.

Job satisfaction assessments of agricultural workers help employers improve the work environment and reduce turnover

Addressing the current labor shortage in California agriculture will require a multi-pronged approach, one of which may be increasing retention of current workers through improved job satisfaction. We developed a questionnaire to evaluate the job satisfaction of agricultural workers in 11 categories, tested the reliability of the questionnaire, and its relationship with worker turnover, in a sample of 665 vineyard workers. In our study, four sources of job satisfaction predicted turnover among Napa vineyard workers: communication, pay, nature of agricultural work, and family commitments. Improving these areas may increase job satisfaction and retention of existing workers to stabilize the agricultural workforce.

Youth in 4-H Latino Initiative programs achieve similar outcomes to youth in 4-H community clubs

Until recently, California 4-H programs did not represent the ethnic diversity found in California's population of young people. To close the gap in representation particularly with Latino youth UC ANR began the 4-H Latino Initiative, an effort to pilot adapted programs that would target the engagement of Latino youth and families. In this paper, we explore and compare young people's program experience and youth development outcomes between 4-H community clubs and 4-H Latino Initiative programs. We employed comparative post-test survey methodology with two treatment groups (community clubs versus 4-H Latino Initiative programs). The findings provide encouraging evidence that young people experienced positive outcomes from participating in 4-H programs, inclusive of both 4-H community clubs and 4-H Latino Initiative programs. Additionally, we found that the program experience including relationship building and youth engagement were similar across community clubs and 4-H Latino Initiative programs.

Agricultural water use accounting provides path for surface water use solutions

Agricultural water demands can conflict with habitat needs in many North Coast watersheds. Understanding different water use patterns can help reduce conflict over limited supplies. We measured on-farm crop water use and conducted grower interviews to estimate the agricultural water demand in the upper Russian River and Navarro River watersheds. Annual agricultural water demand was less than 11% in the Russian River, and 2% in Navarro River, of the total annual discharge in each watershed. However, because demands are concentrated in the dry season when instream flows are at a minimum, these relatively small amounts can represent a significant constraint to stream habitat conditions. We have shared our study results in broad basin and community water resource planning efforts, including flow management of the Russian and Navarro rivers and implementation of the Sustainable Groundwater Management Act in the Ukiah Basin. Findings and recommendations from this study have influenced on-the-ground solutions to meet water demand in these watersheds, including construction of off-stream wintertime storage capacity to replace summertime stream diversions, and use of a municipal recycled water conveyance system as a replacement for summer diversions.

News and Opinion

Hasty responses to foodborne illness outbreaks impact California growers

Four major foodborne illness outbreaks in 3 years have led to stricter requirements for leafy greens growers that may satisfy corporate buyers and reassure the public, but also highlight a serious need for more food safety research.

Research highlights

Recent articles from the Agricultural Experiment Station campuses and UC ANR's county offices, institutes and research and extension centers.

Natural history for all Californians

The California Naturalist program, which links the state's residents with their natural surroundings, is making strides toward addressing its diversity challenges