California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

Current issue and featured articles

October-December 2016
Volume 70, Number 4

Peer-reviewed research and review articles

Calf and yearling prices in California and the western United States
by Tina L. Saitone, Larry C. Forero, Glenn A. Nader, Leslie E. Forero
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An analysis of video auction data reveals how value-added attributes, forward contracts and distance to feeding and processing facilities affect sale prices for beef cattle.
This paper investigates spatial, quality and temporal factors impacting the pricing of calves and yearlings in the western United States using data from a satellite video auction and a hedonic regression framework. Results suggest that spatial price discounts received by western ranchers closely match reported shipping costs and, thus, are consistent with free-on-board pricing and competitive procurement. This study also identifies the presence of temporal price premiums, on average, for seller-offered forward contracts at video auctions. With respect to quality attributes, this study provides estimates of the marginal value associated with various quality attributes and management practices, including vaccination protocols, weaning, certified Angus beef candidates, and age and source verification. Finally, we show that the considerable year-to-year variability in estimated valuations for value-added attributes in hedonic regression models of cattle pricing can be linked to the stage of the cattle cycle, with premiums paid by buyers being attenuated when cattle inventories are high.
Efficacy of selenium supplementation methods in California yearling beef cattle and resulting effect on weight gain
by Josh Davy, Larry Forero, Thomas Tucker, Christie Mayo, Daniel Drake, John Maas, James Oltjen
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In two trials in Tehama County, multiple methods of supplementation produced adequate selenium levels in yearling beef cattle, but worked differently.
Selenium (Se) deficiency occurs commonly in California grazing cattle and has been associated with reduced immune function and, in some studies, reduced weight gain. Multiple methods of supplementing Se are available, but little research has compared the effects of these methods on whole blood Se levels and weight gain. In two trials, we evaluated four methods of Se supplementation — an intrarumenal bolus, two injectable preparations and a loose salt containing 120 ppm Se — over an 85- to 90-day period in Se-deficient yearling cattle in Tehama County. The bolus treatment raised whole blood Se levels to an adequate level (0.08 ppm) for the entire study period. Whole blood Se concentrations in injected cattle initially reached adequate levels but then declined to deficient levels. The loose salt treatment acted slowly, with average whole blood Se concentration reaching adequate levels at the end of the study period. None of the treatments significantly affected weight gain and Se blood concentration was not correlated with weight gain. In growing cattle, it appears that Se supplementation may be viewed not as a direct driver of weight gain, but rather as similar to vaccination, in that it can prevent health problems that might otherwise lead to reduced weight gain.
Practitioner perspectives on using nonnative plants for revegetation
by Elise Gornish, Elizabeth Brusati, Douglas W. Johnson
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In a survey of 192 land managers, 42% considered nonnatives for their projects and 37% had changed their position on nonnatives in response to climate change.
Restoration practitioners use both native and nonnative plant species for revegetation projects. Typically, when rehabilitating damaged working lands, more practitioners consider nonnative plants; while those working to restore habitat have focused on native plants. But this may be shifting. Novel ecosystems (non-analog communities) are commonly being discussed in academic circles, while practical factors such as affordability and availability of natives and the need for more drought tolerant species to accommodate climate change may be making nonnative species attractive to land managers. To better understand the current use of nonnatives for revegetation, we surveyed 192 California restoration stakeholders who worked in a variety of habitats. A large portion (42%) of them considered nonnatives for their projects, and of survey respondents who did not use nonnatives in vegetation rehabilitation, almost half indicated that they would consider them in the future. Across habitats, the dominant value of nonnatives for vegetation rehabilitation was found to be erosion control, and many respondents noted the high cost and unavailability of natives as important drivers of nonnative use in revegetation projects. Moreover, 37% of respondents noted they had changed their opinion or use of nonnatives in response to climate change.
On-farm flood capture could reduce groundwater overdraft in Kings River Basin
by Philip A.M. Bachand, Sujoy B. Roy, Nicole Stern, Joseph Choperena, Don Cameron, William R. Horwath
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A pilot study suggests 30,000 acres would be needed to capture Kings Basin floodwaters, which could reduce groundwater overdraft by one third.
Chronic groundwater overdraft threatens agricultural sustainability in California's Central Valley. Diverting flood flows onto farmland for groundwater recharge offers an opportunity to help address this challenge. We studied the infiltration rate of floodwater diverted from the Kings River at a turnout upstream of the James Weir onto adjoining cropland; and calculated how much land would be necessary to capture the available floodwater, how much recharge of groundwater might be achieved, and the costs. The 1,000-acre pilot study included fields growing tomatoes, wine grapes, alfalfa and pistachios. Flood flows diverted onto vineyards infiltrated at an average rate of 2.5 inches per day under sustained flooding. At that relatively high infiltration rate, 10 acres are needed to capture one CFS of diverted flood flow. We considered these findings in the context of regional expansion. Based upon a 30-year record of Kings Basin surplus flood flows, we estimate 30,000 acres operated for on-farm flood recharge would have had the capacity to capture 80% of available flood flows and potentially offset overdraft rates in the Kings Basin. Costs of on-farm flood capture for this study were estimated at $36 per acre-foot, less than the cost for surface water storage and dedicated recharge basins.

Editorial, News, Letters and Science Briefs

Unlocking the potential for innovation in rural California
by Glenda Humiston
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Unanswered questions for implementation of the Sustainable Groundwater Management Act
by Michael Kiparsky
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The Sustainable Groundwater Management Act challenges the diversity of California farms
by Jessica Rudnick, Alyssa DeVincentis, Linda Estelí Méndez-Barrientos
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Sierra Foothill REC: Quantifying IPM benefits in rangeland systems
by Jim Downing
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Laura Snell: Studying the wild horses of northeastern California
by Jim Downing
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Tina Saitone: Understanding the beef market, and whether sheepdogs are earning their keep
by Jim Downing
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Early view articles

Yield in almond is related more to the abundance of flowers than the relative number of flowers that set fruit
by Sergio Tombesi, Bruce D. Lampinen, Samuel Metcalf, Theodore M. DeJong
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Maximizing healthy populations of productive spurs is key to optimizing yields in commercial almond orchards.
Almond tree yield is a function of the number of flowers on a tree and the percentage of flowers that set fruit. Almonds are borne on spurs (short proleptic shoots that can have both leaves and flowers). Almond tree spur dynamics research has documented that previous year spur leaf area is a predictive parameter for year-to-year spur survival, spur flowering and to a lesser extent spur fruiting, while previous year fruit bearing has a negative impact on subsequent year flowering. However, a question remained about whether yields are more dependent on flower numbers or relative fruit set of the flowers that are present. The aim of the present work was to compare the importance of flower abundance with that of relative fruit set in determining the productivity of a population of tagged spurs in almond trees over a 6-year period. Overall tree yield among years was more sensitive to total number of flowers on a tree rather than relative fruit set. These results emphasize the importance of maintaining large populations of healthy flowering spurs for sustained high production in almond orchards.
Irrigation method does not affect wild bee pollinators of hybrid sunflower
by Hillary Sardiñas, Collette Yee, Claire Kremen
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The number of bees nesting and foraging in drip- versus furrow-irrigated fields were similar, suggesting growers can switch to drip without reducing pollination.
Irrigation method has the potential to directly or indirectly influence populations of wild bee crop pollinators nesting and foraging in irrigated crop fields. The majority of wild bee species nest in the ground, and their nests may be susceptible to flooding. In addition, their pollination of crops can be influenced by nectar quality and quantity, which are related to water availability. To determine whether different irrigation methods affect crop pollinators, we compared the number of ground-nesting bees nesting and foraging in drip- and furrow-irrigated hybrid sunflower fields in the Sacramento Valley. We found that irrigation method did not impact wild bee nesting rates or foraging bee abundance or bee species richness. These findings suggest that changing from furrow irrigation to drip irrigation to conserve water likely will not alter hybrid sunflower crop pollination.
The palm weevil Rhynchophorus vulneratus is eradicated from Laguna Beach
by Mark S. Hoddle, Christina D. Hoddle, Mohammed Alzubaidy, John Kabashima, J. Nicholas Nisson, Jocelyn Millar, Monica Dimson
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A rapid, coordinated response to the discovery of an invasive pest attacking Canary Island date palms in California succeeded in eradicating it.
In October 2010, Rhynchophorus vulneratus, originally identified as the red palm weevil, R. ferrugineus, was discovered infesting Canary Island date palms in Laguna Beach, California. The red palm weevil has caused extensive mortality of palms in the Mediterranean, the Middle East and North Africa, and its discovery in California caused concern for the state's ornamental palm and date industries and the many palms in Southern California landscapes. A rapid, coordinated effort led to the deployment of traps baited with the weevil's aggregation pheromone, coordinated pesticide applications to privately owned palms and destruction of palms at advanced stages of infestation. Research confirmed the chemical components of the aggregation pheromone, assessed the efficacy of trapping strategies and resolved the taxonomic identity, native range and putative region of origin for the population detected in Laguna Beach. The last confirmed detection of a live R. vulneratus was Jan. 20, 2012. USDA-APHIS declared this weevil eradicated from California on Jan. 20, 2015. The estimated cost of the eradication was $1,003,646.
How many workers are employed in California agriculture?
by Philip Martin, Brandon Hooker, Muhammad Akhtar, Marc Stockton
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An analysis of data from agricultural employers suggests that California has a stable agricultural workforce.
In 2014, the average employment of hired workers in California crop and livestock agriculture, counting all occupations, rose by 10% to 410,900. However, although the state reports the number of jobs on farms regularly, it does not report the number of workers who fill these jobs. We analyzed all Social Security numbers reported by farm employers in 2014 and found two workers for each average or year-round equivalent farm job, making the total number of farmworkers employed in agriculture 829,300, or twice average employment. Approximately 83% of farmworkers had their maximum earnings with an agricultural employer in 2014, and almost 80% of those primary farmworkers were employed by crop support firms (392,000) or fruit and nut farms (154,000). Over 60% of all workers had only one farm employer, followed by 27% with two or more farm employers, and 35% were employed in Kern (116,000), Fresno (96,000) and Monterey (82,000) counties. These data show that California has a remarkably stable farm workforce: most farmworkers are attached to one farm employer, often a labor contractor who moves them from farm to farm.
Editor Jim Downing talks about what's in the current issue of California Agriculture journal — wild horses, the economics of beef, groundwater in California and more.


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This article from our latest issue profiles the work of UC Cooperative Extension Advisor Laura Snell, who studies the impacts of wild horses on rangelands in Modoc and Lassen counties. In collaboration with US Forest Service and UC Agriculture & Natural Resources researchers, Snell collects photographic data from wildlife cameras placed for two-week periods at 24 sites; the data will help support management decisions around this controversial subject.

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