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Open Access Publications from the University of California

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

Articles in Press

Articles in Press

Articles that have been peer-reviewed, accepted and edited, but not yet assigned to a print issue.

Research and Review Articles

For California perennial crops facing climate change, water use stays stable while planting density increases

With climate change, there has been increasing concern over allocations of scarce water supplies in California during times of drought. This study looks at how cultural practices in perennial crops have changed over time, specifically related to application of irrigation water and to planting densities. We use University of California Sample Costs of Production Budgets from 1980-2021 for all major perennial crops in California, to compile information on the commonly implemented irrigation and planting practices across various crops and regions. After controlling for regional variation in water applied due to agroclimatic factors, irrigation water use per acre has remained largely stable for most crops, while planting densities have increased for many crops, including olives, grapes, avocados, plums, and almonds. A notable exception is pistachios in the South San Joaquin Valley, which experienced an increase in water applied, with stable yields and planting densities. Our methods of calculating significant trends in water use, including yields and density of orchards, give further insight into the use of water in California agriculture.

Monensin supplementation increases weight gain in stocker steers, but higher doses reduce essential mineral intake

Monensin is known to improve feed efficiency in cattle. At higher doses, however, monensin reduces the palatability of mineral supplements, which may reduce consumption of essential minerals such as selenium. The main objective of this study was to compare weight gain, while evaluating the impact on blood selenium concentrations, among treatment and control groups of stocker calves supplemented with a self-fed mineral supplement designed to deliver different amounts of monensin, while the control group received the same mineral without monensin. A secondary objective was to compare the presence of pathogenic and total coccidia oocysts. At study end, all monensin treatment groups weighed more than the control group but were not different from each other. No effect was detected on coccidia oocysts. In sum, there is a production gain from providing monensin in a mineral supplement to weaned calves on pasture. However, too high a dose may lead to insufficient trace mineral consumption. This is a concern in areas where forage is deficient in these nutrients.

Promoting higher levels of immunity from colostrum among calves on organic dairy farms

Colostrum feeding provides immunoglobulins, in a process called transfer of passive immunity, which is critical for dairy calf health and welfare. However, failure of transfer of passive immunity (FTPI) occurs in about 12% of calves nationwide. This study compares the prevalence of FTPI between calves raised on organic and conventional dairy farms, describes the colostral management practices on organic dairy farms in California, and recommends improvements. We compared serum immunoglobulin G (IgG) concentrations between calves raised on organic and conventional dairies and found that the odds of FTPI in calves raised in organic dairies were 2.5 times greater than in calves raised in conventional dairies. Focusing on varied practices in organic dairies, FTPI was 2.9 times more likely in calves fed less than 4 liters of colostrum within the first 24 hours, compared to calves fed more than that amount. We also found that organic dairy producers did not routinely monitor colostral IgG concentrations and passive immunity status. We recommend that organic dairy farmers adopt these practices to decrease the prevalence of FTPI in calves.

Native blue elderberry in hedgerows bridges revenue and conservation goals

Field edge hedgerows have long been promoted by UC Cooperative Extension and other organizations as a way to bring needed biodiversity to California farms. However, adoption of hedgerow planting still falls far short of available edge capacity. Our study explores a new multifunctional model of hedgerows that combines production with environmental conservation goals by considering the revenue potential of harvesting blue elderberry. Blue elderberry is a drought-tolerant native species well adapted to multiple microclimates in California and the western United States. The growth of elderberry herbal products and specialty foods markets is currently skyrocketing nationally and globally, and blue elderberry may offer a promising entry into these markets. Blue elderberry is also sought out by Indigenous people as one important component in efforts to restore cultural and food sovereignty. A field demonstration trial in the southern Sacramento Valley found that elderberry yields from 1,000-foot-long multi-species hedgerows could potentially provide from $2,000 to $3,000 in net annual revenue within 3 to 5 years, with much more possible as the hedgerows mature.

News and Opinion

When “new” crops are not really new: California Indigenous communities and research and commercialization of elderberry

The article “Native blue elderberry in hedgerows bridges revenue and conservation goals” focuses on the commercial potential of western blue elderberry (Sambucus nigra ssp. cerulea) plantings, primarily on private farmland in California. While blue elderberry is little known as a commercial agricultural crop, it is anything but new to the Indigenous people of this place. Many of the nearly 200 tribes that live in California have been in relationship with elderberry, and the land it grows on, since time immemorial, seeing all living beings as their own kin, rather than merely utilitarian resources. For non-Indigenous farmers and researchers working with elderberry, it is important to be aware of our state’s history of land dispossession and non-Native land management practices, which have often diminished California Native peoples’ access to and sovereignty over traditional foods, medicines and cultural materials.