Source: UNIVERSITY OF CALIFORNIA, DAVIS submitted to
INFLUENCE OF ORCHARD GRAZING ON SOIL HEALTH AND PEST CONTROL WHILE MITIGATING FOOD SAFETY RISKS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1031190
Grant No.
2023-51300-40948
Cumulative Award Amt.
$1,999,867.00
Proposal No.
2023-04450
Multistate No.
(N/A)
Project Start Date
Sep 1, 2023
Project End Date
Aug 31, 2027
Grant Year
2023
Program Code
[113.A]- Organic Agriculture Research & Extension Initiative
Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
(N/A)
Non Technical Summary
Grazing sheep or other animals to convert cover crops to manure infield has a number of practical benefits such as negating labor and costs associated with manure transport, reducing pests, and increasing soil fertility and soil health. Given these benefits, there has been increased interest in the use of cover crops and livestock grazing in nut orchards (almonds, walnuts and pistachios). However, grazing livestock are natural reservoirs for foodborne pathogens, and diet type can increase foodborne pathogen shedding in manure and affect their survival in the soil. While many growers consider livestock grazing of cover-crops on orchards as a way to enhance soil health and environmental benefits, recent concerns about microbial food safety are limiting expansion of this practice because livestock grazing may introduce pathogens into soil with a potential for transfer to nuts. Therefore, we are proposing a multi-regional integrated research-extension approach to fully assess the benefits of livestock integration via cover-crop grazing on bacterial population dynamics, soil health, pest control and economic outcomes to enhance the value of cover crops while limiting food safety risks in organic orchards in two distinct agroecological regions in California. The overall goal of this proposal is to improve the microbial food safety and productivity of organic nuts while maintaining the value of integration of livestock and cover crops in nut production while limiting food safety risks and environmental impacts, and promoting sustainability and biodiversity.
Animal Health Component
80%
Research Effort Categories
Basic
(N/A)
Applied
80%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110106015%
1020110107015%
2111219113030%
7121219110030%
3073610106010%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 211 - Insects, Mites, and Other Arthropods Affecting Plants; 712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins; 307 - Animal Management Systems;

Subject Of Investigation
3610 - Sheep, live animal; 0110 - Soil; 1219 - Edible tree nuts, general/other;

Field Of Science
1060 - Biology (whole systems); 1130 - Entomology and acarology; 1070 - Ecology; 1100 - Bacteriology;
Goals / Objectives
Our long-term goal is to facilitate adoption of organicintegrated crop-livestock systems (ICLS) practices within nut and fruit agriculture throughout the United States, by leveraging the research outputs described in this proposal to create a decision analysis tools encompassing food safety risk, economic cost/benefit, soil enhancement, water conservation, and pest management. These tools would be employed by a diverse range of stakeholders (growers, educators, policymakers, certifiers) to implement and regulate these systems in an evidence-based, economical, and sustainable fashion.The overall objective of this proposal is to develop on-farm research plots in which livestock are integrated into perennial nut crop systems in major production zones to quantify the impacts of sheep grazing of cover crops in organic orchards on soil ecosystems, suppression of common pests of high economic importance, food safety risks, and socioeconomic metrics. Our specific objectives are to measure effects of integrated crop-livestock systems (ICLS) on 1) N availability and soil health (Activity 1); 2) presence and persistence of navel orangeworm (Activity 2); 3) determination of the optimal time-interval between grazing and nut harvesting as a function of environmental & soil parameters to reduce foodborne contamination (Activity 3); 4) determination of the economic costs and benefits of grazing sheep in organic tree nut orchards (Activity 4); and 5) development of an outreach program to guide the implementation of ICL systems in nut production (Activity 5).
Project Methods
Field sites: We will establish field research trials in mature commercial almond, walnut and pistachio orchards located in the Sacramento Valley (SV) and the San Joaquin Valley (SJV) (n=6 trials). Experimental design and management: Four treatments will be established in a randomized split block design with three replicates. Winter cover as main plot treatments and grazing as subplots will be implemented to tease out impacts of cover crop and grazing in isolation or combined. Treatment at the main plot level will consist of 1) planted cover crop (CC) or 2) spontaneous resident vegetation (RV). Grazing treatments will consist of (3) one high density short duration grazing event to terminate cover (G) or 4) ungrazed vegetation (NG), established on subplots by fencing. Plots will be established across the orchard alley on both sides of three tree rows (6 middles). Tree berms will be managed according to grower practices and NG winter covers will be terminated at the time of grazing by mowing. A similar cover crop mix adequate for grazing and to these production zones will be planted at all orchards. Activity 1: Above-ground vegetation biomass and litter quality will be measured before grazing or mowing. Total C and N content of dried above ground plant samples will be measured. Composite soil samples will be taken and analyzed for: Total C and N , POM, pH, CEC, soil inorganic N pools, dissolved Organic C and N pools, Microbial biomass C and N, and Potential Mineralized Nitrogen.Soil samples will be taken in the alleyways at the interface between tree roots and the orchard middles at termination and four weeks following termination to capture shifts in soil health chemical and physical metrics relevant for assessing salinity (EC), compaction (bulk density) and water capture (infiltration rates). Activity 2: Each year in late October and March, all plots at all orchard sites will be surveyed to determine the abundance of remnant nuts prior to ground cover development and sheep grazing activity and post grazing. Each year in early November, cohorts of remnant nuts infested with navel orangeworm will be placed into the various experimental plots. Each year around March 1 a series of egg traps will be placed into the experimental plots to measure egg deposition by first flight navel orangeworm females. Activity 3: A repeated cross-sectional sampling scheme will be conducted in almond, walnut and pistachios orchards (3 nut types X 2 regions X 3 years),following the treatment : 1) planted cover crop (CC), 2) spontaneous resident vegetation (RV) [main plots] and 3) high density grazing (G) and ungrazed vegetation (NG) (planted cover crop (CC), spontaneous resident vegetation (NG) [subplots]. Each orchard will be sampled six times following the growing cycle. Soil, fecal, air and leaf samples will be collected and tested for E. coli O157:H7, non-O157 STEC, Salmonella and indicators of fecal contamination. Further molecular analysis ( WGS of isolates and microbiota analysis) will be conducted from a subset of the samples. Environmental factors, treatment and orchard effect will be analysed using multilevel logistic regression models. A decision- making tool using Bayesian Belief Networs. Activity 4: To quantify associated economic costs and benefits, we will begin by conducting three Cost and Returns Studies for organic almond, pistachio and walnut orchards. Once the cost and returns studies are completed for each crop, we will develop an interactive decision tool that incorporates partial budget analysis methods to analyze a producer's decision of whether to incorporate animal grazing into their organic tree nut production system. Acomprehensive online and in-person (mixed model) outreach program will be developed to provide training for organic producers adopting crop-livestock integration, and industry leaders who seek to purchase from sustainable suppliers.

Progress 09/01/23 to 08/31/24

Outputs
Target Audience:The target audiences reached include various stakeholders in organic nut production, including organic growers, researchers, extension specialists, extension agents, policy makers, experts and industry working/ planning to work with integration of livestock in organic nut production systems. They were reached as part of Advisory Board Annual Meeting, workshops and informal education activities (field days, one -to-one meetings with farmers), and grower meetings. To reach our target audience the Organic Center disseminated a press release to publicize the planned research which was picked up and shared in the California Ag Network media channel (see link in the media listing below). The Organic Center also developed a micro-website where a description of the project, updates, and information has been posted. We also launched and maintained a social media campaign surrounding the research, primarily via The Organic Center, but also through our various UC ANR, UC Davis and UC Riverside accounts.The combined reach of our organizations' social media pages is over 36,000 individuals for Facebook, over 4,800 followers for Instagram, 4,200 Twitter and nearly 1,000 followers on LinkedIn. 1) CA Wool Growers Association, Annual Membership Meeting, August 8, 2024, Paso Robles CA.; 2) 3rd Annual Regenerative Almond Field Day, February 22, 2024. Burroughs Family Farms, Denair; 3) Integrating livestock in organic orchard production in California, Plant and Soil conference, February 2024, Fresno CA; 4) Outcomes and Challenges: Integrating livestock in organic orchard production in California, Agronomy Society of America Meeting, Organic agriculture workshop, Saint Louis, November 2023. Changes/Problems:In the first year, we had some delays with personnel hiring therefore the field trials were postponed one year. The new dates for the field trials are the growing seasons of 2024-2025; 2025-2026 and 2026-2027. The potential grower participants have a cover crop established (ranging from 2 years to > 5 years), therefore one of the treatments (residual vegetation) was removed from the study design. Therefore, to compensate the sample size in the overall study, we increased number of enrolled sites and total of replicates/ samples per farm. Measures of soil health and nutrient cycling have been revised to two time points (before and after 14d after grazing) to accommodate this change and coincide better with other frequent sampling events for foodborne pathogens and mummy nuts. Given these changes in the experimental design, the insect sampling component of this project has been slightly modified. Cohorts of remnant "mummy" nuts infested with navel orangeworm (Lepidoptera: Pyralidae: Amyelois transitella) will still be evaluated before and after grazing, both to observe changes in their abundance as well as survival of overwintering navel orangeworm. Spring monitoring of navel orangeworm egg deposition will no longer be included as a measure of pest control, since the ground covers and grazing will take place prior to this period, and as such we do not expect these practices to have any influence on this pest activity. Previously, spring egg deposition was used as a measure of pest control since participating growers were keeping their ground covers in place late into the spring period, but that is not really reflective of standard agronomic practice in this cropping system. Dr. Goodrich left her position at UC Davis and transitioned to a faculty position at University of Illinois, Urbana-Champaign in August of 2024. She has requested a subaward from UC Davis totaling $74,492. Dr. Goodrich no longer has cost study staff to assist her and the graduate student with the cost benefit analysis, so she has requested her own summer salary funds in lieu of staff salary funding. What opportunities for training and professional development has the project provided?The project provides support for two post-doctoral researchers and undergraduate students, thus helping to build capacity for future professionals in soil health, agroecology, epidemiology and food safety. Dr. Pires, Gaudin and Wilson mentored one post-doctoral researcher each. Dr Pires also mentored 1 undergraduate student at UC Davis. How have the results been disseminated to communities of interest?The field trials haven't started, so no results to share with the communities of interest. What do you plan to do during the next reporting period to accomplish the goals?We will establish field trials in certified mature commercial almond (3), walnut (3) and pistachio (1) orchards located in the Sacramento Valley and the San Joaquin Valley. Two main treatments will be studied: 1) cover crops and grazing and 2) cover crops and not grazing. Cover crop re-seeding is expected in 2024 Fall, and grazing starting in the Spring of 2025. The field trial(s) sampling for soil health, microbiology and pest control will start in the 2024 fall or 2025 spring (depending on grazing events frequency). We will continue with the planned outreach program (website updates, participation in conferences and grower-based meetings; and advisory board meeting).

Impacts
What was accomplished under these goals? Growers located in Sacramento Valley and San Joaquim Valley were contacted and invited to participate in the field trials. 3 growers were visited in person to discuss the project and 5 growers (3 Almond orchards, 1 Pistachio and 3 Walnut sites) have been invited to participate. Initial study design is being discussed with the growers (Activities 1-3). The farm sites were selected to represent different growing climates (including soil type and weather patterns), irrigation practices, planted cover crop, and grazing practices. A short survey of their farming practices was conducted prior to the enrollment. Baseline microbiological testing of soil, and fecal samples will start in the fall of 2024 (Activity 3). Optimization of microbiological testing for generic E. coli and foodborne pathogens was conducted in soil, leaves and fecal material (Activity 3). An advisory board meeting was conducted with the participation of representatives of the nut commodities (almond, walnut, and pistachio), no-profit organizations (organic and food safety), consultants, extension farmer advisors and specialist growers. The project was announced through a press release and several media interactions to stakeholders, industry, grower groups and consumers. We developed (hosted by The Organic Center) a dedicated public-facing website for the project (Activity 5).

Publications

  • Type: Conference Papers and Presentations Status: Accepted Year Published: 2024 Citation: Cheong S*, Carolyn-Khayd*, Pires A#. Evaluating the presence of foodborne pathogens of crop-integrated crop-livestock in CA orchards (Abst. # 305). 17th International Symposium on Veterinary Epidemiology and Economics, 2024 ISVEE, November 11-15, 2024, Sydney, Australia. Poster presentation (accepted).
  • Type: Websites Status: Published Year Published: 2024 Citation: Website: https://www.organic-center.org/site/influence-orchard-grazing-soil-health-food-safety-and-pest-control