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Open Access Publications from the University of California

Volume 69, Issue 2, 2015

Water: New approaches to aquifer recharge

Issue cover
Cover Caption: Complete contents, including news and editorial featuresA field of tomatoes is irrigated with groundwater at the Russell Ranch Sustainable Agriculture Facility near UC Davis. California’s prolonged drought is driving major increases in groundwater extraction in the state’s agriculture regions. UC researchers are investigating new ways to recharge aquifers (page 75). Photo by Will Suckow.

Research and Review Articles

Soil suitability index identifies potential areas for groundwater banking on agricultural lands

Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater — when surface water is available — is to deliberately flood an open area, allowing water to percolate into an aquifer. However, open land suitable for this type of recharge is scarce. Flooding agricultural land during fallow or dormant periods has the potential to increase groundwater recharge substantially, but this approach has not been well studied. Using data on soils, topography and crop type, we developed a spatially explicit index of the suitability for groundwater recharge of land in all agricultural regions in California. We identified 3.6 million acres of agricultural land statewide as having Excellent or Good potential for groundwater recharge. The index provides preliminary guidance about the locations where groundwater recharge on agricultural land is likely to be feasible. A variety of institutional, infrastructure and other issues must also be addressed before this practice can be implemented widely.

Regional identity can add value to agricultural products

Regional identity creation is being recognized for its economic benefits and as a strategic resource for producer communities. A regional identity is not a brand; it is built through a complicated process of developing cohesion and sharing in the industry community and communicating outside the industry community to opinion-makers and consumers. The California fine wine industry has built successful regional identities and leveraged them to add value to their wines. As regional identities in the wine industry have strengthened, so has the industry, and a symbiotic relationship with other local value-added industries, such as tourism and hospitality, has emerged. Other agricultural producers can learn from the identity creation experiences in the wine industry. With the many challenges faced by California agriculture, identity formation may offer producers new ideas for adding value to their products and finding larger markets.

Scientific literacy: California 4-H defines it from citizens' perspective

Scientific literacy is an important educational and societal goal. Measuring scientific literacy, however, has been problematic because there is no consensus regarding the meaning of scientific literacy. Most definitions focus on the content and processes of major science disciplines, ignoring social factors and citizens’ needs. The authors developed a definition of scientific literacy for the California 4-H Program from the citizen's perspective, concentrating on real-world science-related situations. The definition includes four anchor points: science content; scientific reasoning skills; interest in and attitudes toward science; and contribution through applied participation. The definition provides the California 4-H Science, Engineering, and Technology Initiative with a framework for future science curriculum and program development and implementation, educator professional development, and evaluation.

WIC fruit and vegetable vouchers: Small farms face barriers in supplying produce

By October 2009, all 50 states had implemented a revised WIC program with produce vouchers for millions of eligible families. USDA economists had projected the vouchers would raise net farm revenues by $76 million. In response to such a significant policy change and market opportunity, a UC Agriculture and Natural Resources Cooperative Extension team of researchers conducted a pilot project to test the ability of small farms to market produce locally to WIC-authorized stores known as A-50 vendors. They also interviewed store owners and produce distributors to determine how produce was entering the supply chain to the A-50 vendors. The pilot project was not successful in helping small growers enter the supply chain. The analysis indicates that it is improbable that small farms will be selling much produce to A-50 vendors; growers’ price expectations are unlikely to be met since these vendors are competing with large retailers. And although the vouchers can be redeemed at farmers markets, very few are because the process is cumbersome for growers and shoppers.

UCCE efforts improve quality of and demand for fresh produce at WIC A-50 stores

In 2005, the Institute of Medicine recommended major revisions in the food packages provided by the federal Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), leading to new regulations that allow participants to purchase a wide variety of fruits and vegetables with their vouchers. In support of this policy change, UC Agriculture and Natural Resources Cooperative Extension (UCCE) developed educational materials to promote fresh produce among WIC participants and offered postharvest handling training at WIC-only stores, known as A-50 vendors, in order to improve produce quality. A survey conducted after the educational sessions found that WIC participants had increased knowledge of produce and A-50 vendors showed improved postharvest handling after the education sessions. This research demonstrates that combining nutrition education with postharvest handling curriculum can lead to a successful educational program that supports increased demand among WIC participants for fresh produce.

Network-smart extension could catalyze social learning

Social learning, learning from others, has value in extending knowledge about farm management through networks of growers. Exactly how much value depends on the structure of the networks. We employed social network analysis to study knowledge networks and social learning in three American Viticulture Areas in California: Central Coast, Lodi and Napa Valley. In a survey, growers confirmed that experiential and social learning are more useful for accessing information about farm management than formal learning. UC Agriculture and Natural Resources Cooperative Extension (UCCE) was found to be well positioned to access and spread knowledge through the grower networks but a bottleneck exists — many knowledge-sharing relationships and relatively few staff. We also found that grower participation in traditional outreach activities, e.g., meetings and demonstrations, is a strong predictor of their number of knowledge-sharing relationships, so UCCE and other agricultural support organizations have an important role to play in strengthening networks. Several network-smart extension strategies might help alleviate the bottleneck and rewire networks to more efficiently connect those with questions to those with solutions.

Howard walnut trees can be brought into bearing without annual pruning

In traditionally managed Howard walnut orchards, trees are pruned annually during the orchard development phase, an expensive operation in terms of labor and prunings disposal costs. Our observations and some prior research by others had suggested that pruning may not be necessary in walnut. In a trial of pruned and unpruned hedgerow trees over 8 years, beginning a year after planting, we documented canopy growth, tree height, yield and nut quality characteristics and also the effects of fruit removal. Pruning altered canopy shape but did not lead to increases in canopy development, yield or nut quality. Although fruit removal stimulated more vegetative growth in both the pruned and unpruned treatments, fruit removal did not result in an increase in midday canopy photosynthetically active radiation interception or cumulative yield when fruit removal was stopped after year 4. After 8 years, there were no significant differences in tree height, nut quality or cumulative yield among any of the treatments, which suggests that not pruning young Howard orchards could provide a net benefit to growers.

Editorial, News, Letters and Science Briefs

UC ANR Cooperative Extension grows citizen scientists

Last year, as part of the May 8 centennial of the founding of the Cooperative Extension Service in the United States, UC ANR Cooperative Extension (UCCE) invited Californians to take a walk or visit a park or garden and be citizen scientists. The goals were to crowd-source information on pollinators, water use, and food production and consumption and to give participants a shared experience of observing and reporting on the world around them.

Barbara Allen-Diaz: A career applying research to solve California's problems

After more than 4 years as the leader of UC Agriculture and Natural Resources, Barbara Allen-Diaz is retiring June 30. Ann Senuta, UC ANR Director of Publishing, provides this retrospective on her career.