California Agriculture
California Agriculture
California Agriculture
University of California
California Agriculture

Current issue and featured articles

CAv071n03
Special Issue
The UC Global Food Initiative
July-September 2017
Volume 71, Number 3
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EDITORIAL
UC and California food systems: Growing together through the Global Food Initiative
by Janet Napolitano
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The will and the ingenuity to think big and take bold action has always been the hallmark of California agriculture and the connection between the industry and the University of California runs deep.
UC GLOBAL FOOD INITIATIVE UPDATE
The UC Global Food Initiative
Editors
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This special issue of California Agriculture features news and research articles illustrating the breadth of activities and research that make up the UC Global Food Initiative (GFI).
UC GLOBAL FOOD INITIATIVE UPDATE
Urban agriculture and food disparities
Editors
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Working at the intersection of technology, civic society and sustainability to build food security and community-university connections.
UC GLOBAL FOOD INITIATIVE UPDATE
Increasing experiential learning opportunities in food and agriculture
Editors
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A new report from the Global Food Initiative identifies hands-on learning opportunities for UC students.
UC GLOBAL FOOD INITIATIVE UPDATE
Moving toward zero waste dining
Editors
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A new toolkit helps food service operators identify opportunities to reduce waste.
UC GLOBAL FOOD INITIATIVE UPDATE
Ensuring basic access to food for UC students
Editors
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Each campus is working toward food security for all by 2020.
UC GLOBAL FOOD INITIATIVE UPDATE
Extending agricultural knowledge globally
Editors
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An international agricultural fellowship program has supported graduate students working in 24 countries — conducting research, providing training, overseeing field trials and more.
UC GLOBAL FOOD INITIATIVE UPDATE
Food hubs: The logistics of local
Editors
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Connecting small farms with big buyers — like UC campuses.

Peer-reviewed research and review articles

Hedgerow benefits align with food production and sustainability goals
by Rachael F. Long, Kelly Garbach, Lora A. Morandin
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Adoption of hedgerows on California farms shows benefits and a return on investment in 7 to 16 years.
Restoring hedgerows, or other field edge plantings, to provide habitat for bees and other beneficial insects on farms is needed to sustain global food production in intensive agricultural systems. To date, the creation of hedgerows and other restored habitat areas on California farms remains low, in part because of a lack of information and outreach that addresses the benefits of field edge habitat, and growers' concerns about its effect on crop production and wildlife intrusion. Field studies in the Sacramento Valley highlighted that hedgerows can enhance pest control and pollination in crops, resulting in a return on investment within 7 to 16 years, without negatively impacting food safety. To encourage hedgerow and other restoration practices that enhance farm sustainability, increased outreach, technical guidance, and continued policy support for conservation programs in agriculture are imperative.
Long-term agricultural experiments inform the development of climate-smart agricultural practices
by Kristina Wolf, Israel Herrera, Thomas P. Tomich, Kate Scow
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Studying cropping systems over decades illuminates slow-changing but important effects on soil carbon, soil biota, water holding capacity and more.
California's Mediterranean agro-ecosystems are a major source of U.S. fruits and vegetables, and vulnerable to future extremes of precipitation and temperature brought on by climate change, including increased drought and flooding, and more intense and longer heat waves. To develop resilience to these threats, strategies are necessary for climate-smart management of soil and water. Long-term, large-scale, replicated ecological experiments provide unique testbeds for studying such questions. At the UC Davis Russell Ranch Sustainable Agriculture Facility (RRSAF), the 100-year Century Experiment, initiated in 1992, is investigating the effects of multiple farming practices in a farm-scale replicated study of 10 row crop cropping systems. It includes different fertility management systems: organic, conventional and hybrid (conventional plus winter cover crop) systems; different crops: wheat, tomatoes, corn, alfalfa, cover crops and grasslands; and different irrigation systems: rainfed, flood irrigated and drip irrigated. We briefly describe and report on a selection of long-term experiments conducted at RRSAF investigating soil management and irrigation practices, which are an important focus for developing climate-smart strategies in Mediterranean systems. For example, long-term monitoring of soil carbon content revealed that most crop systems have experienced a small increase in soil carbon since 1993, and increases in organically managed plots were substantially higher. As RRSAF continues to build upon this rich dataset from one of a very few long-term row crop experiments in Mediterranean ecosystems, it provides a testbed for identifying climate-smart solutions for these agronomically important ecosystems.
Getting the farm to the school: Increasing direct, local procurement in Yolo County schools
by Gail Feenstra, Shosha Capps, Kristy Lyn Levings, Elaine James, Mary Laurie, Mitchell Maniti, Emma Lee
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Data on in-season produce purchases and a collection of “forager” services support direct and seasonal sales from farms to schools.
Since 2012, the UC Sustainable Agriculture Research and Education Program (SAREP) has worked with the Yolo County Department of Agriculture to support farm to school activities in Yolo County. In 2015, SAREP partnered with the Yolo County Department of Agriculture to deepen engagement with Yolo County growers and increase direct sales to Yolo County schools. SAREP tracked the volumes and prices of produce purchased by five school districts for the 2014–2015 baseline year and the 2015–2016 school year. Analysis was completed for three school districts for common produce items purchased, increases in in-season purchasing and direct grower versus distributor sales. For these districts, 17 produce items were in the top 10 for at least one of the districts; the five most common were apples, bananas, lettuce, oranges and strawberries, four of which are available locally for some or all of the school year. Districts purchased between 50% and 75% of their produce in season by the end of year two. All districts increased their purchases directly from growers. Findings suggest how services for growers and school food buyers can contribute to more local procurement.
College students identify university support for basic needs and life skills as key ingredient in addressing food insecurity on campus
by Tyler D. Watson*, Hannah Malan*, Deborah Glik, Suzanna M. Martinez
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Food insecurity is a persistent stressor for some students; food literacy may help improve student well-being.
A recent University of California (UC) systemwide survey showed that 42% of UC college students experience food insecurity, consistent with other studies among U.S. college students. As part of UC's efforts to understand and address student food insecurity, we conducted 11 focus group interviews across four student subpopulations at UC Los Angeles (n = 82). We explored student experiences, perceptions and concerns related to both food insecurity and food literacy, which may help protect students against food insecurity. Themes around food insecurity included student awareness about food insecurity, cost of university attendance, food insecurity consequences, and coping strategies. Themes around food literacy included existing knowledge and skills, enjoyment and social cohesion, and learning in the dining halls. Unifying themes included the campus food environment not meeting student needs, a desire for practical financial and food literacy “life skills” training, and skepticism about the university's commitment to adequately address student basic needs. The results of this study broadly suggest there is opportunity for the university to address student food insecurity through providing food literacy training, among other strategies.
UC pursues rooted research with a nonprofit, links the many benefits of community gardens
by Mirle Rabinowitz Bussell, James Bliesner, Keith Pezzoli
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A study of eight San Diego County community gardens demonstrates their role in gardeners' health and well-being and community development.
The informal economy, healthy food options and alternative urban food systems are interconnected in important ways. To better understand these connections, and explore a rooted university approach to working with communities, we collaborated with the San Diego Community Garden Network to analyze the production, distribution and consumption of produce from eight community gardens in San Diego County. The project engaged UC San Diego researchers and students with county residents and community-based organizations to develop a survey together. Interviews with the gardeners and data from the completed survey document the ways in which community gardens contribute to individual and household health, well-being and community development. They suggest that despite perceptions that community gardens have marginal commercial capacity, they have the potential to contribute in meaningful ways to community development, particularly in low-income neighborhoods.
N2O emissions from California farmlands: A review
by Elizabeth Verhoeven, Engil Pereira, Charlotte Decock, Gina Garland, Taryn Kennedy, Emma Suddick, William Horwath, Johan Six
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Emissions estimates of nitrous oxide from the state's croplands are currently based on global average emission factors and derived from N inputs; local management practices should also be taken into account.
Of the greenhouse gases emitted from cropland, nitrous oxide (N2O) has the highest global warming potential. The state of California acknowledges that agriculture both contributes to and is affected by climate change, and in 2016 it adopted legislation to help growers reduce emissions of greenhouse gases, explicitly including N2O. Nitrous oxide emissions can vary widely due to environmental and agronomic factors with most emission estimates coming from temperate grain systems. There is, however, a dearth of emission estimates from perennial and vegetable cropping systems commonly found in California's Mediterranean climate. Therefore, emission factors (EFs) specific to California conditions are needed to accurately assess statewide N2O emissions and mitigation options. In this paper, we review 16 studies reporting annual and seasonal N2O emissions. This data set represents all available studies on measured emissions at the whole field scale and on an event basis. Through this series of studies, we discuss how such farm management and environmental factors influence N2O emissions from California agriculture and may serve as a basis for improved EF calculations.
Review of research to inform California's climate scoping plan: Agriculture and working lands
by Ryan Byrnes, Valerie Eviner, Ermias Kebreab, William R. Horwath, Louise Jackson, Bryan M. Jenkins, Stephen Kaffka, Amber Kerr, Josette Lewis, Frank M. Mitloehner, Jeffrey P. Mitchell, Kate M. Scow, Kerri L. Steenwerth, Stephen Wheeler
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California's diverse agricultural systems offer a range of opportunities for reducing climate-warming emissions.
Agriculture in California contributes 8% of the state's greenhouse gas (GHG) emissions. To inform the state's policy and program strategy to meet climate targets, we review recent research on practices that can reduce emissions, sequester carbon and provide other co-benefits to producers and the environment across agriculture and rangeland systems. Importantly, the research reviewed here was conducted in California and addresses practices in our specific agricultural, socioeconomic and biophysical environment. Farmland conversion and the dairy and intensive livestock sector are the largest contributors to GHG emissions and offer the greatest opportunities for avoided emissions. We also identify a range of other opportunities including soil and nutrient management, integrated and diversified farming systems, rangeland management, and biomass-based energy generation. Additional research to replicate and quantify the emissions reduction or carbon sequestration potential of these practices will strengthen the evidence base for California climate policy.
Biocontrol program targets Asian citrus psyllid in California's urban areas
by Ivan Milosavljević, Kelsey Schall, Christina Hoddle, David Morgan, Mark Hoddle
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Two parasitoids of the Asian citrus psyllid, from Pakistan, have been released in Southern California with promising results.
In California, Asian citrus psyllid vectors the bacterium Candidatus Liberibacter asiaticus, which causes the lethal citrus disease huanglongbing. The top priority for California's citrus industry has been to diminish the rate of bacterium spread by reducing Asian citrus psyllid populations in urban areas, where this pest primarily resides. Attempts at eradicating and containing the psyllid with insecticides were unsuccessful. An alternative approach has been a classical biological control program using two parasitoids from Pakistan, Tamarixia radiata and Diaphorencyrtus aligarhensis, which attack the psyllid nymphs. T. radiata has established widely and, in combination with generalist predators, natural enemies are providing substantial control of psyllids in urban areas.
The economics of managing Verticillium wilt, an imported disease in California lettuce
by Christine L. Carroll, Colin A. Carter, Rachael E. Goodhue, C.-Y. Cynthia Lin Lawell, Krishna V. Subbarao
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Successfully controlling Verticillium wilt requires future investment, but there is no incentive for short-term growers who rent land to absorb those costs; nor is there incentive for spinach seed companies to test or clean spinach seeds.
Verticillium dahliae is a soilborne fungus that is introduced to the soil via infested spinach seeds and that causes lettuce to be afflicted with Verticillium wilt. This disease has spread rapidly through the Salinas Valley, the prime lettuce production region of California. Verticillium wilt can be prevented or controlled by the grower by fumigating, planting broccoli, or not planting spinach. Because these control options require long-term investment for future gain, renters might not take the steps needed to control Verticillium wilt. Verticillium wilt can also be prevented or controlled by a spinach seed company through testing and cleaning the spinach seeds. However, seed companies are unwilling to test or clean spinach seeds, as they are not affected by this disease. We discuss our research on the externalities that arise with renters, and between seed companies and growers, due to Verticillium wilt. These externalities have important implications for the management of Verticillium wilt in particular, and for the management of diseases in agriculture in general.
Land access and costs may drive strawberry growers' increased use of fumigation
by Julie Guthman
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The phaseout of methyl bromide and increasing regulation of other fumigants did not decrease overall fumigant use in California strawberries. Here are some likely reasons why.
2016 marked the year of the final phaseout of methyl bromide for use in strawberry production. During the long phaseout period, one replacement fumigant met so much public opposition it was taken off the market, while restrictions on use of other fumigants increased. As part of a larger study on the challenges facing the strawberry industry, I tracked fumigant use through California's pesticide use reporting system from 2004 to 2013. During the last few years before the phaseout, I interviewed 74 growers in the four main strawberry production regions about how they were now managing soilborne pests. As a general trend, growers had increased their use of chloropicrin and switched from broadcast fumigation to bed fumigation, and many were experimenting with organics. At the same time, significant percentages of growers were reluctant to change fumigation regimes or adopt nonchemical options of pathogen control. Some were unable to adopt less chemical-intensive methods because of land access conditions and land costs. Given these land-related obstacles, policymakers ought to consider strategies that will incentivize transitions to nonchemical alternatives and mitigate the financial risks.

Early view articles

PEER-REVIEWED
Farmers share their perspectives on California water management and the Sustainable Groundwater Management Act
by Meredith T. Niles, Courtney Hammond Wagner
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Focus groups with Yolo County farmers demonstrate that farmers' perceptions of and responses to the regulation are important to its success.
Agriculture is the largest human use of water in California, which gives farmers a critical role in managing water to meet the goals of the Sustainable Groundwater Management Act (SGMA). To explore farmers' perspectives on SGMA, we held focus groups with 20 farmers in Yolo County, where the groundwater basin has been given a high/medium priority under SGMA. The farmers had varying perspectives about the factors that led to SGMA and varying responses to the regulation. They suggested that drought, competing agricultural and urban uses, and an increase in perennial crops were factors in recent water use, resulting in changes to water quality and quantity. Impacts of those changes included variable well levels, increased infrastructure costs, and ecosystem impacts, which farmers had responded to by implementing multiple management strategies. Additional research in other regions is imperative to provide farmers' viewpoints and strategies to policymakers, irrigation districts, farmer cooperatives, and the agricultural industry and give farmers a voice at the table.
PEER-REVIEWED
Forage seeding in rangelands increases production and prevents weed invasion
by Josh S. Davy, Katherine Dykier, Tony Turri, Elise Gornish
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In a seeding study in the California foothills, annual ryegrass and soft brome performed well in the short term, and Flecha tall fescue, several hardinggrass varieties and Berber orchardgrass worked well in the long term.
Increasing forage productivity in the Sierra foothill rangelands would help sustain the livestock industry as land availability shrinks and lease rates rise, but hardly any studies have been done on forage selections. From 2009 to 2014, in one of the first long-term and replicated studies of seeding Northern California's Mediterranean annual rangeland, we compared the cover of 22 diverse forages to determine their establishment and survivability over time. Among the annual herbs, forage brassica (Brassica napus L.) and chicory (Cichorium intybus L.) proved viable options. Among the annual grasses, soft brome (Bromus hordeaceus) and annual ryegrass (Lolium multiflorum) performed well. However, these species will likely require frequent reseeding to maintain dominance. Long-term goals of sustained dominant cover (> 3 years) are best achieved with perennial grasses. Perennial grasses that persisted with greater than 50% cover were Berber orchardgrass (Dactylis glomerata), Flecha tall fescue (Lolium arundinaceum) and several varieties of hardinggrass (Phalaris aquatica L., Perla koleagrass, Holdfast, Advanced AT). In 2014, these successful perennials produced over three times more dry matter (pounds per acre) than the unseeded control and also suppressed annual grasses and yellow starthistle (Centaurea solstitialis L.) cover.
PEER-REVIEWED
Volunteer educators bring their own ideas about effective teaching to a 4-H curriculum
by Steven Worker
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Pragmatic and structural constraints shaped the pedagogical choices volunteer educators made, as did their professional identification and comfort with engineering.
Youth programs implemented during out-of-school time often rely on volunteers. These volunteers are responsible for selecting and adapting curriculum and facilitating activities, so their pedagogical practices become primary contributors to program quality, and ultimately, youth outcomes. To describe volunteers' pedagogical practices, I conducted a qualitative case study at three sites where volunteer educators were implementing a design-based 4-H curriculum. The curriculum advanced youth scientific literacy by supporting scientific inquiry in conjunction with planning, designing and making shareable artifacts. Through detailed observations, videos and focus groups, I identified six common pedagogical practices, though educators differed widely in which ones they used. Pragmatic and structural constraints shaped their choices, as did their professional identification as engineers, or not, and their relative comfort with engineering. To support volunteer educators in implementing a learner-centered educational program, curricula designers might be more specific in recommending and explaining pedagogical practices, and program managers might better train volunteer educators in those preferred practices.
PEER-REVIEWED
Modeling identifies optimal fall planting times and irrigation requirements for canola and camelina at locations across California
by Nicholas George, Lucia Levers, Sally Thompson, Joy Hollingsworth, Stephen Kaffka
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Sufficient rainfall and appropriate soil temperatures during the canola planting window occur statewide on average 1 in 3 years, but camelina is significantly more drought and cold tolerant.
In California, Brassica oilseeds may be viable crops for growers to diversify their cool-season crop options, helping them adapt to projected climate change and irrigation water shortages. Field trials have found germination and establishment problems in some late-planted canola, but not camelina at the same locations. We used computer modeling to analyze fall seedbed conditions to better understand this phenomenon. We found seedbeds may be too dry, too cold, or both, to support germination of canola during late fall. Based on seedbed temperatures only, canola should be sown no later than the last week of November in the Central Valley. Camelina has broader temperature and moisture windows for germination and can be sown from October to December with less risk, but yields of camelina are lower than canola yields. In areas without irrigation, growers could plant canola opportunistically when seedbed conditions are favorable and use camelina as a fallback option.
PEER-REVIEWED
Automated lettuce thinners reduce labor requirements and increase speed of thinning
by Elizabeth Mosqueda, Richard Smith, Dave Goorahoo, Anil Shrestha
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Automated thinners were as accurate in thinning lettuce as manual thinning, produced comparable yields, and were more than three times faster than thinning crews.
Salinas Valley lettuce growers are adopting automated lettuce thinners to improve labor efficiency. We conducted field studies in 2014 and 2015 to compare the time involved in automated and manual thinning of direct-seeded lettuce and any differences in lettuce quality and yield. We recorded the number of doubles (two closely spaced plants) left behind after thinning, time taken to remove the doubles, final crop stand, efficiency in weed removal, crop yield and disease incidence. Using an automated thinner in place of manual hoeing reduced the thinning labor requirement from 7.31 ± 0.5 person-hours per acre to 2.03 ± 0.5 person-hours per acre. Automated thinning left more doubles than manual thinning, resulting in additional time to remove them, but was overall more labor-efficient and had no impact on yield or disease incidence.
PEER-REVIEWED
Remote sensing is a viable tool for mapping soil salinity in agricultural lands
by Elia Scudiero, Dennis L. Corwin, Ray G. Anderson, Kevin Yemoto, Wesley Clary, Zhi “Luke” Wang, Todd H. Skaggs
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Remote-sensing modeling produces an accurate regional salinity map of the western San Joaquin Valley, useful for growers and state agencies.
Soil salinity negatively impacts the productivity and profitability of western San Joaquin Valley (WSJV) farmland. Many factors, including drought, climate change, reduced water allocations, and land-use changes could worsen salinity conditions there, and in other agricultural lands in the state. Mapping soil salinity at regional and state levels is essential for identifying drivers and trends in agricultural soil salinity, and for developing mitigation strategies, but traditional soil sampling for salinity does not allow for accurate large-scale mapping. We tested remote-sensing modeling to map root zone soil salinity for farmland in the WSJV. According to our map, 0.78 million acres are salt affected (i.e., ECe > 4 dS/m), which represents 45% of the mapped farmland; 30% of that acreage is strongly or extremely saline. Independent validations of the remote-sensing estimations indicated acceptable to excellent correspondences, except in areas of low salinity and high soil heterogeneity. Remote sensing is a viable tool for helping landowners make decisions about land use and also for helping water districts and state agencies develop salinity mitigation strategies.
Here's a quick video introduction to California Agriculture's special issue on the UC Global Food Initiative. We have an editorial from UC President Janet Napolitano, six stories on the initiative's accomplishments, and 10 research papers on ... hedgerows, pollinators, the Century long-term experiment at UC Davis, farm-to-school sourcing of produce, campus food insecurity, the multiple benefits of community gardens, greenhouse gas emissions from agriculture in the state, a promising biocontrol program for the Asian citrus psyllid, and two papers on the economic aspects of managing soilborne pests on the central coast. Enjoy!

 

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In 2015, the UC Sustainable Agriculture Research and Education Program worked with the Yolo County Department of Agriculture "to build the capacity of local growers in and around Yolo County to sell more products directly to school food service buyers."

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