California Agriculture Research Articles

The Salton Sea: An introduction to an evolving system and the role of science

In this special issue, California Agriculture presents review articles that highlight what research to date can say about the changing Salton Sea ecosystem and its environmental and human health–related impacts, and identify areas in which further scientific research is needed to better inform policy.

Use of Beef Semen on Dairy Farms: A Cross-Sectional Study on Attitudes of Farmer Toward Breeding Strategies

The use of beef semen on dairy cows has been increasing steadily since 2017. We aimed to describe dairy management practices toward the use of beef semen by surveying farmers in California, the largest US dairy producer. In January 2020, we mailed a printed version of the beef semen use survey to 1,017 dairy producers in California, who also had the option to answer the survey online. The questionnaire consisted of 33 questions that were categorized into three sections: general herd information (n = 10), beef semen management (n = 17), and sexed dairy semen management (n = 6). The response rate was 13.9% (n = 141). Regression models were used to evaluate the associations between the dairy-beef crossbred sale price, use of beef semen, and use of sexed dairy semen vs. herd characteristics. The mean ± SD herd size was 1,693 ± 1,311 milking cows. Most dairies (81%) reported using beef semen on dairy cows. Among respondents, 78% reported extra profit as the main advantage of using beef semen, followed by control of heifer inventory (69%), genetic improvement (37%), and other factors (8%). Most respondents (58%) started using beef semen in the past 3 years and 34% of the respondents were breeding more than 30% of all the eligible cows with beef semen. Angus semen was the most used (reported by 89% of the respondents), followed by Limousin (12%), Wagyu (10%), Charolais (7%), others (5%, Limflex, Stabilizer, and Hereford), and Simmental (4%). Reproductive performance was an important criterion to select cows to receive beef semen and 45% of the respondents reported starting breeding cows with beef semen from the third breeding, 18% on the fourth breeding, and 21% on the fifth or greater breedings. The region of California (a proxy for type of production system) contracts with a calf ranch and the herd breed explained 76.7% of the observed variation in the day-old dairy beef crossbred calf price. Survey results demonstrated the widespread use of beef semen in dairies and the main breeding strategies adopted by dairy farmers.

Isotopic Signatures of Methane Emissions From Dairy Farms in California’s San Joaquin Valley

AbstractIn this study, we present seasonal atmospheric measurements of δ13CCH4 from dairy farms in the San Joaquin Valley of California. We used δ13CCH4 to characterize emissions from enteric fermentation by measuring downwind of cattle housing (e.g., freestall barns, corrals) and from manure management areas (e.g., anaerobic manure lagoons) with a mobile platform equipped with cavity ring‐down spectrometers. Across seasons, the δ13CCH4 from enteric fermentation source areas ranged from −69.7 ± 0.6 per mil (‰) to −51.6 ± 0.1‰ while the δ13CCH4 from manure lagoons ranged from −49.5 ± 0.1‰ to −40.5 ± 0.2‰. Measurements of δ13CCH4 of enteric CH4 suggest a greater than 10‰ difference between cattle production groups in accordance with diet. Isotopic signatures of CH4 were used to characterize enteric and manure CH4 from downwind plume sampling of dairies. Our findings show that δ13CCH4 measurements could improve the attribution of CH4 emissions from dairy sources at scales ranging from individual facilities to regions and help constrain the relative contributions from these different sources of emissions to the CH4 budget.

Risk factors of Shiga toxin-producing Escherichia coli in livestock raised on diversified small-scale farms in California.

The increasing number of diversified small-scale farms (DSSF) that raise outdoor-based livestock in the USA reflects growing consumer demand for sustainably produced food. Diversified farms are small scale and raise a combination of multiple livestock species and numerous produce varieties. This 2015-2016 cross-sectional study aimed to describe the unique characteristics of DSSF in California, estimate the prevalence of Shiga toxin-producing Escherichia coli (STEC) in livestock and evaluate the association between risk factors and the presence of STEC in livestock, using generalised linear mixed models. STEC prevalence was 13.62% (76/558). Significant variables in the mixed-effect logistic regression model included daily maximum temperature (OR 0.95; CI95% 0.91-0.98), livestock sample source (cattle (OR 4.61; CI95% 1.64-12.96) and sheep (OR 5.29; CI95% 1.80-15.51)), multiple species sharing the same barn (OR 6.23; CI95% 1.84-21.15) and livestock having contact with wild areas (OR 3.63; CI95% 1.37-9.62). Identification of STEC serogroups of public health concern (e.g. O157:H7, O26, O103) in this study indicated the need for mitigation strategies to ensure food safety by evaluating risk factors and management practices that contribute to the spread and prevalence of foodborne pathogens in a pre-harvest environment on DSSF.

Life Cycle Assessment of Eight Urban Farms and Community Gardens in France and California

Life Cycle Assessment of Eight Urban Farms and Community Gardens in France and California

Farm labor productivity and the impact of mechanization

AbstractThere is a chronic shortage of agricultural labor in the US. Although growers increasingly turn to guest‐worker programs to meet their labor needs, few regard immigrant workers as a viable long‐term solution. Many producers of labor‐intensive agricultural commodities regard mechanization as a clear long‐term solution, making the slow rate of adoption of mechanized harvesting equipment in the US an empirical puzzle. In this article, we demonstrate that wage‐setting farmers have an incentive to “overmechanize,” or employ more than the cost‐minimizing level of capital when capital and labor are substitutes, but “undermechanize” when labor and capital are technical complements. This outcome can cause agricultural labor problems to persist under complementarity. To assess the potential role of farm under investment in labor augmenting capital equipment, we examine labor market outcomes following the adoption of non‐autonomous harvesting aids on a large strawberry farm in Central California. We develop an econometric model of peer‐affected productivity that controls for the group performance of farm workers operating in crews and find that mechanical aids complement labor in strawberry production, a finding that helps explain not only the relative lack of mechanized harvesting in strawberry production but, more generally, the persistent productivity gap in agricultural industries. We examine the broader implications of our theory for the slow rate of adoption of mechanical harvesting technologies in US agriculture by comparing general wage trends across several labor‐intensive and non‐labor‐intensive industries in California.

Mandatory information-based policy tools facilitate California farmers’ learning about nitrogen management

This article evaluates farmer learning in response to a nitrogen management policy adopted in California. California’s policy features a mandatory information-based approach, particularly education and plan-writing, wherein farmers must report their farm management practices and nitrogen application rates to regional water quality districts. Using survey data from farmers across three regions in California’s Central Valley, we employ a sequential ordered logistic regression to evaluate how this policy impacts farmer learning across two stages: a conceptual learning stage where farmers take in new information and re-think their farm management, and an applied learning stage where they report substantial change to behavior. Our findings show that behavioral drivers have different effects on learning across each stage. Early conceptual learning is driven by farmers’ awareness of agriculture’s environmental impact, positive attitudes towards environmental stewardship, and positive perceptions of the nitrogen management regulators. Later stage applied learning is driven primarily by high levels of informational support. We also find that farm and farmer resource variables such as farmer income and education are negative predictors of both learning stages, indicating that lower-resourced farmers are beneficiaries of mandatory plan-writing. Results suggest that mandatory information-based tools can prompt learning among lower-resourced farmers who are often slow to engage in voluntary conservation programs. For improving learning outcomes, policies for conservation behavior should tailor support to these different stages of learning.

In the Struggle: Scholars and the Fight Against Industrial Agribusiness in California

In the Struggle: Scholars and the Fight Against Industrial Agribusiness in California

Alternative Chemical Control Options and Monitoring Techniques for Triops longicaudatus (Notostraca: Triopsidae) in California Rice.

The tadpole shrimp (Triops longicaudatus (Leconte); Notostraca; Triopsidae) is a vernal pool crustacean that has emerged as a significant pest for many rice farmers in California. Currently, lambda-cyhalothrin is the commercial standard and sole management practice for TPS, but resistance appears to be emerging. Field and laboratory trials were conducted from 2015 to 2018 at the Rice Experiment Station in Biggs, California, and in greenhouses at the University of California (UC) Davis to evaluate the efficacy of several alternative chemical controls and to explore early indicators of TPS activity and damage as monitoring tools. TPS mortality in plots treated with azadirachtin was not significantly different from those in the untreated control across all trials. Copper sulfate, lambda-cyhalothrin, and clothianidin were consistently effective across both lab and field trials. Chlorantraniliprole generated effective control in four of the five trials, whereas two diflubenzuron rates generated adequate control in the field, but not in laboratory bioassays. Thus, there appear to be several effective alternative control options available for farmers, should resistance to lambda-cyhalothrin continue to spread. Water turbidity (measured using a scale of 1-4) and the number of dislodged seedlings were both significantly correlated with TPS counts in field studies. Turbidity exhibited the highest correlations with TPS counts, suggesting that with further refinement it could play a valuable role in monitoring TPS populations.

Photovoltaic solar farms in California: can we have renewable electricity and our species, too?

Photovoltaic solar power generating facilities are proliferating rapidly in California and elsewhere. While this trend is welcomed for many reasons (e.g., reducing greenhouse gas emissions), these facilities also can have profound environmental impacts, particularly to local species populations. These impacts become more significant when species of conservation concern are affected. In the San Joaquin Desert region in central California, a number of conservation measures have been routinely implemented on solar facilities, and these measures have facilitated continued use of the facilities by a number of species of conservation concern. Some of the more significant measures include permeable security fences, vegetation management, movement corridors, avoiding critical features such as dens and burrows, and vehicle speed limits. Detailed studies have been conducted on San Joaquin kit foxes (Vulpes macrotis mutica) using solar facilities in the San Joaquin Desert. Demographic and ecological attributes of foxes are similar between foxes using the facilities and foxes on nearby reference sites, and values for foxes on solar sites are within the ranges of values for foxes reported from sites within core population areas. Facilitated by the conservation measures, kit foxes are using at least six facilities in the San Joaquin Desert as are a variety of other species of conservation concern. This successful model also potentially could be adapted to other ecosystems and applied to facilities in regions outside of the San Joaquin Desert, such as the Mojave Desert. Determining whether species in other regions can use photovoltaic solar facilities and identifying the most efficacious conservation measures will require time and testing, and these efforts would benefit from collaborative efforts among landowners, solar developers, natural resources agencies, researchers, and others. The San Joaquin Desert facilities and a recent demonstration facility in the Mojave Desert provide strong evidence that solar facilities can be constructed and operated in a manner that also accommodates continued use of the facilities by some species of conservation concern.

‘Your’s Truly’: The Creation and Consumption of Commercial Tourist Portraits

There is a long history of tourists substantiating their visits to a destination through the purchase of portraits that show them against a backdrop of the local setting. While its initial expression in the form of paintings was confined to the social elite who could afford to commission and sit for an artist, the advent of photography democratized the process, enabling the aspiring middle classes to partake in the custom. While some tourists took their own photographs, the majority relied on local photographers who offered their services in studio and open-air settings. Smaller-sized images, such as Cartes de Visite (2.5″ × 4″) and Cabinet Cards (4.5″ × 6.5″), could be enclosed with letters to family and social circles, thus providing proof of visits while the voyage was still in progress. The development of picture postcards as a postal item in the 1890s, coupled with the manufacture of precut photographic paper with preprinted address fields, revolutionized tourist portraiture. Photographers could set-up outside tourist attractions, where tourists could have their portrait taken with formulaic framing against a canonized background. Efficient production flows meant that tourists could pick up their printed portraits, ready for mailing within an hour. Using examples of San Marc’s Basilica in Venice (Italy), as well as Ostrich Farms in California and Florida (U.S.A.), this paper contextualizes the production and consumption of such commercial tourist portraits as objects of social validation. It discusses their ability to situate the visitor in locales iconic of the destination, substantiating their presence and validating their experience. Given the speed of production (within an hour) and their ability to be immediately mailed through the global postal network, such images were the precursor of the modern-day ‘selfies’ posted on social media.

Treatment practices after calving-related events on 45 dairy farms in California

Retained fetal membranes (RFM), dystocia, and twinning are common postpartum events that increase the risk of metritis, impair reproductive performance, and contribute to antimicrobial use on dairies. The overall objective of this study was to describe treatment decisions after RFM, severe dystocia (cesarean section and fetotomy), nonsevere dystocia (nonmechanical and mechanical assistance to extract the calf), and twinning. A total of 44 dairies from California's San Joaquin Valley (39 Holstein and 6 Jersey or crossbreed herds) with 450 to 9,500 lactating cows were enrolled in this study. Researchers visited each dairy once to observe cow-side fresh cow health evaluations and to interview health evaluators and maternity workers, using a standardized survey tool. The survey included questions about antimicrobial (class, dose, and duration) and nonantimicrobial therapies for calving-related events. Antimicrobial therapy was used in all 44 dairies to treat RFM at 24 (n = 23), 48 (n = 10), or 72 h (n = 5) after calving, or when puerperal metritis signs were observed (n = 6). Antimicrobial therapy was used after all severe dystocia cases, and after nonsevere dystocia (n = 27) and twinning (n = 15). Ceftiofur products were the most common antimicrobial class; they were used to treat RFM cases (n = 29), nonsevere dystocia (n = 13), and twinning (n = 10). Supportive therapy for calving-related events included nonantimicrobial intrauterine treatments, nonsteroidal antiinflammatory drugs, oxytocin, i.v. calcium, or oral drenches. Our study highlights opportunities to reduce extra-label use of antimicrobials in postpartum cows affected with RFM, and the need for education and outreach efforts on judicious use of antimicrobials. Furthermore, antimicrobial treatment choices differed largely across dairies, indicating a need to reach consensus and promote standardized practices within the industry.

Antibiotic Resistance Genes and Associated Phenotypes in Escherichia coli and Enterococcus from Cattle at Different Production Stages on a Dairy Farm in Central California.

The objectives of this study were to characterize overall genomic antibiotic resistance profiles of fecal Escherichia coli and Enterococcus spp. from dairy cattle at different production stages using whole-genome sequencing and to determine the association between antimicrobial resistance (AMR) phenotypes and their corresponding genotypes. The Comprehensive Antibiotic Resistance Database (CARD) and ResFinder, two publicly available databases of antimicrobial resistance genes, were used to annotate isolates. Based on the ResFinder database, 27.5% and 20.0% of tested E. coli isolates (n = 40) harbored single and ≥3 antimicrobial resistance genes, respectively; for Enterococcus spp., we observed 87.8% and 8.2%, respectively. The highest prevalence of AMR genes in E. coli was for resistance to tetracycline (27.5%), followed by sulphonamide (22.5%) and aminoglycoside (20.0%); the predominant antimicrobial resistance genes in Enterococcus spp. targeted macrolide drugs (77.6%). Based on the CARD database, resistance to ≥3 antimicrobial classes was observed in all E. coli and 77.6% in Enterococcus spp. isolates. A high degree of agreement existed between the resistance phenotype and the presence of resistance genes for various antimicrobial classes for E. coli but much less so for isolates of Enterococcus. Consistent with prior work, fecal E. coli and Enterococcus spp. isolates from calves harbored a wide spectrum of resistance genes, compared to those from cattle at other production stages, based on the cross-sectional samples from the studied farm.

Regenerative Almond Production Systems Improve Soil Health, Biodiversity, and Profit

Regenerative agriculture aims to improve soil health and promote biodiversity while producing nutritious food profitably. Almonds are the dominant crop in California agriculture in terms of acreage and revenue generated. We examined the soil health, biodiversity, yield, and profit of regenerative and conventional almond production systems that represented farmer-derived best management practices. Regenerative practices included abandoning some or all synthetic agrichemicals, planting perennial ground covers, integrating livestock, maintaining non-crop habitat, and using composts and compost teas. Total soil carbon (TSC), soil organic matter (SOM), total soil nitrogen (TSN), total soil phosphorous, calcium, sulfur, and soil health test scores were all significantly greater in regenerative soils. Water infiltrated regenerative soils six-fold faster than conventional soils. Total microbial biomass, total bacterial biomass, Gram+ bacteria, and Actinobacteria were significantly greater in regenerative soils. There was more plant biomass, species diversity, and percent cover in regenerative orchards. Invertebrate richness and diversity, and earthworm abundance and biomass were significantly greater in regenerative orchards. Pest populations, yields, and nutrient density of the almonds were similar in the two systems. Profit was twice as high in the regenerative orchards relative to their conventional counterparts. No one practice was responsible for the success of regenerative farms; their success was the result of simultaneously combining multiple regenerative practices into a single, functional farm system. This style of farming may assist in combatting planetary scale problems (e.g., climate change, biodiversity loss, agricultural pollution, chronic human health problems, and declining rural communities) while making farms more profitable and resilient.

Dairy management practices associated with multi-drug resistant fecal commensals and Salmonella in cull cows: a machine learning approach

BackgroundUnderstanding the effects of herd management practices on the prevalence of multidrug-resistant pathogenic Salmonella and commensals Enterococcus spp. and Escherichia coli in dairy cattle is key in reducing antibacterial resistant infections in humans originating from food animals. Our objective was to explore the herd and cow level features associated with the multi-drug resistant, and resistance phenotypes shared between Salmonella, E. coli and Enterococcus spp. using machine learning algorithms.MethodsRandomly collected fecal samples from cull dairy cows from six dairy farms in central California were tested for multi-drug resistance phenotypes of Salmonella, E. coli and Enterococcus spp. Using data on herd management practices collected from a questionnaire, we built three machine learning algorithms (decision tree classifier, random forest, and gradient boosting decision trees) to predict the cows shedding multidrug-resistant Salmonella and commensal bacteria.ResultsThe decision tree classifier identified rolling herd average milk production as an important feature for predicting fecal shedding of multi-drug resistance in Salmonella or commensal bacteria. The number of culled animals, monthly culling frequency and percentage, herd size, and proportion of Holstein cows in the herd were found to be influential herd characteristics predicting fecal shedding of multidrug-resistant phenotypes based on random forest models for Salmonella and commensal bacteria. Gradient boosting models showed that higher culling frequency and monthly culling percentages were associated with fecal shedding of multidrug resistant Salmonella or commensal bacteria. In contrast, an overall increase in the number of culled animals on a culling day showed a negative trend with classifying a cow as shedding multidrug-resistant bacteria. Increasing rolling herd average milk production and spring season were positively associated with fecal shedding of multidrug- resistant Salmonella. Only six individual cows were detected sharing tetracycline resistance phenotypes between Salmonella and either of the commensal bacteria.DiscussionPercent culled and culling rate reflect the increase in culling over time adjusting for herd size and were associated with shedding multidrug resistant bacteria. In contrast, number culled was negatively associated with shedding multidrug resistant bacteria which may reflect producer decisions to prioritize the culling of otherwise healthy but low-producing cows based on milk or beef prices (with respect to dairy beef), amongst other factors. Using a data-driven suite of machine learning algorithms we identified generalizable and distant associations between antimicrobial resistance in Salmonella and fecal commensal bacteria, that can help develop a producer-friendly and data-informed risk assessment tool to reduce shedding of multidrug-resistant bacteria in cull dairy cows.

Cannabis farms in California rely on wells outside of regulated groundwater basins

As permitted cannabis farming in California continues to expand statewide, including in ecologically sensitive watersheds, an improved understanding of water-use practices is needed. Existing evidence suggests widespread reliance on groundwater wells for cannabis irrigation may result in streamflow depletion, yet our understanding of where and why well use for cannabis is most prevalent is currently limited. Here, we use California state cannabis permitting data to address four important information gaps regarding well use by cannabis farming: (1) the prevalence of groundwater wells as an irrigation source for regulated cannabis farms statewide, (2) the extent to which groundwater use occurs outside of regulated groundwater basins, (3) the most useful predictors of whether a farm will rely on groundwater for irrigation, and (4) the potential well use from cannabis farms that are currently unpermitted. Well use by cannabis farms is common statewide, with percentages in excess of 75% among permitted farms in nine of the 11 top cannabis producing counties. In eight of these 11 counties, more than one quarter of farms using wells are located outside of groundwater basins subject to state groundwater use regulations. We found that cultivation area size was a positive predictor of well use, while annual precipitation and on-farm stream network density were negative predictors, highlighting the influences of water demand and surface water availability. The output of a machine learning model trained with data from permitted farms in Northern California suggests that the majority (60%) of unpermitted farms are likely to use groundwater wells if they follow the same patterns as the regulated industry. Our results suggest that proactive steps be taken to address groundwater use in cannabis regulations in California and call for further research into the effects of groundwater use on streamflow, especially outside of large groundwater basins.

Why comply? Farmer motivations and barriers in cannabis agriculture

Cannabis legalization is spreading rapidly. In California, as the plant transitions from an illegal drug to agricultural product, regulations have been implemented to manage its production and associated environmental impacts. Yet, at the early stages of this process, many of the state's cannabis farmers continue to operate illicitly. This study examines why some cannabis farmers are engaging in the state's licensing initiative while others are not. Through an anonymous survey of cannabis farmers in California, we analyzed socio-normative and cost-related factors influencing farmers' decisions to participate in legal markets, or not. Approximately one third of the 362 cannabis farmers who completed the survey reported that they had never applied for a license. These non-compliant farmers were likely to be smaller cultivators who grew cannabis as part of a diversified livelihood strategy. Farmers' non-compliance was primarily attributed to an inability to overcome barriers to participation. These included not only financial barriers but also administrative and psychological ones, all of which disproportionately affect farmers with fewer resources. Socio-normative factors, including pressure from neighbors and perspectives on the benefits of environmental regulations, were not found to motivate non-compliance. As a result, policy efforts to mitigate the administrative burdens of compliance, such as streamlining permitting processes, extending agricultural support services, and supporting farmer collectives, warrant further attention to enhance compliance, public safety, environmental outcomes, and rural development in cannabis cultivating communities. Reforms to promote compliance, particularly among smaller farmers, may prevent the kinds of industrial consolidation seen in agricultural and in other governmental efforts to regulate informal resource use and trade.

Feeding high amounts of almond hulls to lactating cows

California is the leading state for the production of almonds, with more than 400,000 bearing hectares of orchards that produced approximately 1 billion kilograms of shelled nuts in 2017. Almond hulls (AH) are a regional by-product feedstuff fed predominantly to dairy cattle in California. A 2012 study surveyed 40 dairy farms in California and found that 39 out of 104 total mixed rations contained AH, with a mean daily feeding rate of 1.45 kg/cow. In 2017, approximately 2 billion kilograms of AH was produced. At a feeding rate of 1.45 kg/cow daily, even if all 1.7 million lactating cows in California are consuming AH, there will be a surplus of AH on the market as the approximately 130,000 nonbearing hectares come into nut production. Therefore, the potential of feeding varying amounts of AH to lactating dairy cows was investigated using 12 Holstein cows with 4 primiparous and 8 multiparous cows. The dietary treatments were 4 total mixed rations containing 0, 7, 13, or 20% AH. The AH used contained 12.8% crude fiber (as-is basis), which was below the 15% legal limit set by state feed regulations. Diets were formulated so that as the inclusion rate of AH increased, the amount of steam-flaked corn and soyhull pellets decreased and soybean meal inclusion increased. Experimental design was a replicated 4 × 4 Latin square. Diet had a cubic effect on actual milk yield, energy-corrected milk yield, and dry matter intake, with the 7% AH diet having the highest values and the 13% AH diet having the lowest. The percent and yield of total solids and the yields of lactose and fat did not differ with diet, but percent and yield of protein declined linearly with increased AH inclusion, and fat percent increased linearly. Apparent total-tract digestibilities of dry matter and organic matter were higher with the inclusion of AH in the diet. Total percentage of the day spent ruminating increased linearly with higher amounts of AH. Overall, this work demonstrated that AH can be fed at varying amounts, up to 20% of the diet, to lactating dairy cows to support high levels of milk production and that increasing amounts of AH (up to 20%) in the diet could lead to improved digestibility and milk fat percentage but decreased milk protein production.

Water and Light‐Use Efficiency Are Enhanced Under Summer Coastal Fog in a California Agricultural System

AbstractIn coastal California, the peak growing season of economically important crops is concurrent with fog events, which buffer drought stress during the dry season. Coastal fog patterns are changing, so we quantified its effects on the energy, water, and carbon fluxes of a strawberry farm located in the fog‐belt of the Salinas Valley, California. We used Geostationary Operational Environmental Satellite (GOES) total albedo to detect and quantify large scale patterns of coastal fog. We used eddy covariance (EC) to quantify actual evapotranspiration and gross primary productivity (GPP) at the field scale (approximately 0.5–3 hectares) from June to September 2016. We measured canopy‐scale (approximately 0.6 m2) strawberry physiology on foggy and non‐foggy days within the measurement footprint of the EC tower. Downwelling longwave radiation (L↓), observed by a surface‐mounted pyrgeometer, was consistently higher on foggy compared to clear‐sky days (regardless of fog‐drip), indicating that emission of longwave radiation was derived almost entirely from the cloud base. L↓ and total GOES albedo were positively and strongly correlated (R2 = 0.68, P < 0.01). For both field‐ and canopy‐scales, water‐use and light‐use efficiency increased by as much as 50% and 70%, respectively, during foggy compared to non‐foggy conditions. The initial slope of the curvilinear relationship fit between GPP and photosynthetically active radiation was twice as steep during foggy (α = 0.0395) than non‐foggy (α = 0.0210) conditions, suggesting that the scattering of light during fog events enhances photosynthetic output of whole‐plants. Our results suggest that irrigation for these fields could be rescheduled during foggy periods without sacrificing plant productivity.

Special issue: Community and citizen science

In this special issue, California Agriculture presents research and news on community and citizen science projects across California.