Source: UNIVERSITY OF CALIFORNIA, BERKELEY submitted to
FARMING SOIL HEALTH ON CALIFORNIA’S CENTRAL COAST: POLICY DRIVERS, ON-FARM INNOVATIONS, AND ECOLOGICAL OUTCOMES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
NEW
Funding Source
Reporting Frequency
Annual
Accession No.
1019335
Grant No.
2019-67019-29537
Project No.
CA-B-INS-C3TB-CG
Proposal No.
2018-06856
Multistate No.
(N/A)
Program Code
A1401
Project Start Date
Jun 1, 2019
Project End Date
May 31, 2022
Grant Year
2019
Project Director
Bowles, T.
Recipient Organization
UNIVERSITY OF CALIFORNIA, BERKELEY
(N/A)
BERKELEY,CA 94720
Performing Department
Environmental Science, Policy, and Management
Non Technical Summary
Loss of soil biodiversity, depletion of soil organic matter (SOM) and pollution of groundwater by nitrate leaching are some of the many widespread consequences of intensive, highly-simplified agricultural systems, which undermine the natural resource base on which agriculture depends and threaten the health of rural communities across the United States. Restoration of soil health, an integrative concept describing the dynamic properties of soil,especially soil microbes and soil organic matter,that underpin key soil functions is increasingly recognized as a crucial step toward creating more sustainable agroecosystems by enhancing soil-based ecosystem services. Biologically diversified farming systems use management practices at multiple temporal and spatial scales that promote beneficial organisms in the farm and the surrounding landscape, thereby supplying critical ecosystem services that can result in production improvements with fewer inputs.Yet knowledge of how suchpractices (for instance, cover crops, organic matter amendments, and crop rotation) affect soil microbes and SOM and the ecosystem services they together underpin remains limitedon working farms, especially in high-intensity vegetable systems. Further,such techniques are often not adopted by farmers because of multiple, reinforcing market, knowledge, agronomic, environmental, and policy barriers.In this project, we willassess how diversified farming systems affect soil health and soil-based ecosystem services, and the key barriers, motivations, and conditions for advancing beneficial soil health outcomes in an intensive agricultural landscape, using a set of lettuce farms in California's Central Coast region as our research site.The Central Coast, also known as America's "Salad Bowl", exhibits strong tradeoffs between agricultural production and environmental outcomes (e.g. high value crops but severely impaired water quality), as well as factors like high land values and food safety concerns that could make using soil health building practices more challenging compared to other regions.We will determinehow government policies (including regulations and incentives) and supply chain requirements influence farmers' decisions to adopt or not to adopt diversified farming practices using semi-structured interviews with up to 30 farmers and other agricultural professionals, as well as a quantitative socio-economic survey. Based on these interviews, we will then identify a gradient of diversification practices acrossthe same set of farms, from highly specialized farms using few or none of these practices to highly-diversified farms using several. Along this gradientwe will measure soil microbial community composition and diversityandindicators of key soil-based ecosystem services, including potential for soil carbon sequestration, nitrogen retention, water conservation, as well as lettuce yields. To facilitate knowledge exchange among farmers, we will host two on-farmfield days and facilitate farmer-to-farmer knowledge exchange along with discussion of quantitative results on ecological outcomes and economic tradeoffs and benefits of diversification practices in the Central Coast region. Through this research, we anticipatedocumenting the extent to which on-farm innovations lead to beneficial soil health outcomes andincrease the adoption of soil health practices through design of better policy incentives (based in part on this scientific data) and increasing farmers' awareness of both opportunities and challenges.
Animal Health Component
0%
Research Effort Categories
Basic
70%
Applied
30%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1020110107040%
1364099108030%
6056030308030%
Goals / Objectives
The overarchinggoals of this project areto: 1) document the extent to which on-farm innovations using diversification practices (DPs) lead to beneficial soil health outcomes; and 2) increase adoption of soil health practices through design of better policy incentives (based in part on this scientific data) as well as increasing farmers' awareness of both opportunities and challenges.To achieve these research goals, we will investigate four objectives:Analyze how government policies, incentives, and supply chain conditions influence farmer's decisions to adopt, modify, or abandon DPs.Determine how field-scale DPs impact the soil microbiome, and the extent to which these impacts depend on landscape-scale complexity.Determine how field-scale DPs impact soil-based ecosystem services, and how these services correlate with soil microbial abundance, activity and/or diversity.Analyze how farmers become aware of the opportunities and challenges of adopting DPs to promote soil health, including economic tradeoffs.
Project Methods
Our biodiversity, ecosystem service, and socio-economic studies will be focused on farms that grow lettuce with or without other crops. We will use publicly available databases to identify the population of organic lettuce growers in California's Central Coast (America's "salad bowl", recruiting and selecting ~30 farm sites which vary independently along two gradients: local diversity (varying in number and type of diversification practices [DPs]); and landscape heterogeneity of surrounding landscapes (from highly simplified to highly diversified). To determine barriers and opportunities for adoption of DPs to promote soil health, we will conduct: (1) detailed interviews with ~30 farmers participating in ecological research and with key informants (Obj. 1) (e.g. University of California Cooperative Extension and Resource Conservation District field advisers, food suppliers, and state and federal government officials). To characterize soil health and its functions, we will: (1) inventory soil microbial communities (Obj 2) and (2) measure selected ecosystem functions, services and disservices (Obj. 3) To increase awareness of the challenges and opportunities of using DPs to promote soil health (Obj. 4), in Year 3, we will host two on-farm field days and facilitate farmer-to-farmer knowledge exchange along with discussion of quantitative results on ecological outcomes and economic tradeoffs and benefits of DPs in this landscape.While each of the objectives will have disciplinary analyses and publications, our priority is to integrate and synthesize these data to create interdisciplinary conclusions and recommendations. In line with our overarching goals (see Introduction), our major aim is to inform science-based policies and farming learning pathways that enhance adoptions of DPs to promote soil health, by identifying how DPs (and which ones) enhance SOM and soil microbiota, and identifying the factors that drive adoption of DPs. Two specific cross-cutting examples include: 1) If landscape complexity is important for restoring the diversity of soil microbes in lettuce production fields, then policies aimed at enhancing soil health should focus on both field- and landscape-scale practices (e.g. hedgerows and riparian corridors); 2) If farmers report that they mostly learn from talking with neighboring farmers and observing practices, then outreach efforts should focus on on-farm demonstration projects and facilitating farmer-to-farmer knowledge exchange.

Progress 06/01/19 to 05/31/20

Outputs
Target Audience:During this reporting period we reached a variety of target audiences through a number of different venues. Through our stakeholder advisory committee we reached; 1) several farmers in the Central Coast region of California growing high value vegetable crops (including new farmers, Spanish Speaking farmers, and resource-limited farmers); 2) extension personnel (e.g. from University of California Cooperative Extension, California Resource Conservation Districts [CARCD], and the Natural Resource Conservation Service) involved in vegetable crop and organic crop production; 3) staff from non-profit organizations working at the intersection of agriculture and the environment; and 4) University of California researchers. At our stakeholder meeting we presented our target audience with our preliminary findings and received feedback from them on our field sampling campaign and farm management surveys. An audience of technical assistance providers was also reached through presentations at the California Plant-Soil Conference and the CARCD conference. Farmers were reached through a panel presentation at the Eco Farm conference. Undergraduates were also reached during formal classroom instruction through PI Bowles' courses in Agroecology (55 upper division students) and Introduction to Environmental Science (300 lower division students), each of which includes a relevant unit on agriculture and soil health. Graduate students were reached through formal classroom instruction by both PI Bowles and co-PI Iles through a Food Systems course on a unit about policies to support soil health in California. Changes/Problems:We had to make some adjustments to our research approaches due to the COVID-19 pandemic. UC Berkeley human subjects requirements forbid us from going to the field to do interviews, focus groups, or site visits. This means we must currently rely on phone conversations and online surveys to gather our data. This has set back the social science part to some degree but we have a very robust interview dataset from last year that we are building on. Nevertheless, it has also opened a new line of inquiry developed in response to the widespread impacts of the COVID-19 pandemic. The social science team is now examining the ways in which farm diversification influences resilience/vulnerability and adaptive capacity to systemic shocks such as the one created by this crisis. Additionally, lab analysis will be delayed due to the impacts of the COVID pandemic as we have stringent restrictions on how many people can be in a lab space simultaneously. Overall, in spite of large challenges, we were able to obtain exemptions to continue research during the initial lock-down, and our project remains largely on track. What opportunities for training and professional development has the project provided? The project has created numerous informal training and professional development opportunities such as the opportunity for early career researchers to work with an interdisciplinary team, learn about the administration and management of large projects, train in social science research methods, increase professional networks, and outreach through workshops, blogs, and conferences. One participant noted that they would now feel much more comfortable writing such a grant and taking on leadership of a project such as this one. Two postdoc fellows continued their research training as part of the project. Those postdocs received training in publication, data analysis, and soil health and biodiversity issues. One obtained an assistant professor position at the University of Rhode Island in part because of the experiences he gained through the project. The project also provided research experience for several undergraduate students who have gained experience in various laboratory techniques, remote sensing skills, and will also be included in the downstream analysis and paper write up. How have the results been disseminated to communities of interest?Preliminary results have been shared with our stakeholder advisory board (growers, cooperative extension agents, etc..) at an advisory meeting hosted in March, as well as presentations to the California Plant-Soil Society and the California Association of Resource Conservation Districts. Our initial results and tentative survey and field sampling methods were shared with the stakeholders in order for them to provide insight into how we could make the sampling and management survey relevant to our communities of interest. What do you plan to do during the next reporting period to accomplish the goals?Now that the field sampling campaign has been completed our efforts will be concentrated on finishing the lab and statistical analyses and continuing to work on reports and manuscripts. Specifically, in order to measure soil microbial diversity, we will extract DNA from five soil samples from each field and submit the DNA for 16S and ITS2 amplicon sequencing. We will also measure the potential of each farm to provide ecosystem services including soil carbon storage, water regulation, and nitrogen regulation by measuring various indicators on our soil samples including, but not limited to, total soil carbon and nitrogen, soil hydraulic conductivity, and soil nitrate and ammonium. In addition to the ecological work planned for the next year, we plan to finish data collection from the farm management surveys and semi-structured interviews and relate the results to our ecological data. We would also like to focus on outreach in the next year, especially with the development of reports based on our findings from the grower interviews, supply chain interviews, and grower practices survey.

Impacts
What was accomplished under these goals? Loss of soil biodiversity, depletion of soil organic matter (SOM) and pollution of groundwater by nitrate leaching are some of the many widespread consequences of intensive, highly-simplified agricultural systems, which undermine the natural resource base on which agriculture depends and threaten the health of rural communities across the United States. Restoration of soil health, an integrative concept describing the dynamic properties of soil, especially soil microbes and soil organic matter, that underpin key soil functions is increasingly recognized as a crucial step toward creating more sustainable agroecosystems by enhancing soil-based ecosystem services. Biologically diversified farming systems use management practices at multiple temporal and spatial scales that promote beneficial organisms in the farm and the surrounding landscape, thereby supplying critical ecosystem services that can result in production improvements with fewer inputs. Yet knowledge of how such practices (for instance, cover crops, organic matter amendments, and crop rotation) affect soil microbes and SOM and the ecosystem services they together underpin remains limited on working farms, especially in high-intensity vegetable systems. Further, such techniques are often not adopted by farmers because of multiple, reinforcing market, knowledge, agronomic, environmental, and policy barriers. In this reporting year we made progress on both Objectives 1 and 2, setting us up to realize Objectives 3 and 4. For Goal 1, we completed our soil sampling campaign by sampling soils across 28 farms that lie on a gradient of diversification practice usage and have made ample progress analysing soil chemical, biological, and physical properties. We have begun our community analysis of soil microbial diversity as well as the analyses that estimate soil ecosystem service potential including soil carbon sequestration, nitrogen retention, water conservation, as well as lettuce yields. As for Goal 2, a team of ecologists, soil scientists, social scientists, and agricultural economists came together to design a farm management survey that not only would elucidate which type of farmers use what practices but also determine what were the barriers to adoption of diversification practices. The survey data is still being collected (remotely due to Covid) but will be used to help increase farmer adoption of diversification practices from better policy incentives. Objective 1: Analyze how government policies, incentives, and supply chain conditions influence farmer's decisions to adopt, modify, or abandon DPs; and Objective 4: Analyze how farmers become aware of the opportunities and challenges of adopting DPs to promote soil health, including economic tradeoffs. (socio-economic objectives) Led by co-PD Iles, postdocs and two key collaborators conducted 55 semi-structured interviews with growers, technical assistance providers/extension personnel, and produce processors about decisions to adopt or support diversification practices for soil health. All interviews have been transcribed and preliminary qualitative analyses have been conducted. A farm management survey was sent out to determine how farmers use or do not use several diversification practices (cover cropping, crop rotation, organic amendments, and perennial vegetation) as well as what are the primary obstacles to using them. We identified a loose typology of farms that helps explain why these decisions play out differently for different farmers, including small-scale, medium-scale and large-scale farms. Smaller-scale farms in the region tend to be resource limited and have insecure land tenure, limiting their capacity to use diversification practices for long periods of time, especially when this cuts into production of high value crops in a region with very high land costs. Large scale farms face slim profit margins and must respond to global market demands, also limiting their capacity to incorporate diversification practices. We identified medium scale farmers as a potential "sweet spot" for using diversification practices in this region, based on typically more secure land tenure and regional markets that value stewardship, Based on other grower and technical support interviews we have also found that food safety requirements from buyers are key to how growers make decisions about what practices they use, especially as some buyers forbid the use of compost due to concerns about pathogen transmission. Tight production schedules, including often two or more cash crops per year, and high land values make it very difficult to use cover cropping, even though most growers would like to do more cover cropping to improve soil health. Growers have several innovative approaches for incorporating cover crops when and where they can, such as only cover cropping a proportion of their farms each year, and identifying short time periods over the summer when fast growing cover crops can be produced on the same beds used for vegetable production. Some growers are using over-wintering cash crops like broccoli to serve as nitrogen interceptors while also allowing for some income. Based on these initial findings, we have already begun to draft several articles specifically about farmer decision making and its impact on the natural system. Objective 2: Determine how field-scale DPs impact the soil microbiome, and the extent to which these impacts depend on landscape-scale complexity; and Objective 3: Determine how field-scale DPs impact soil-based ecosystem services, and how these services correlate with soil microbial abundance, activity and/or diversity. (ecological objectives) We conducted a biophysical survey across 28 different lettuce fields (16 different growers) in California's central coast, mainly during Spring 2020. The fields fall along a "diversification gradient" (i.e. they vary in the extent to which diversification practices are used), which was based off the initial interviews and initial site visits. We quantified landscape-level crop diversity by visually mapping and then digitizing all crop types within 500 m of each farm. We also manually digitized non-crop vegetation in the surrounding landscape (within 1 km) using NAIP and Google Earth aerial imagery which will be used to determine our landscape heterogeneity index. At each field, we sampled soil at three key times during the lettuce's growing season: transplant, mid-season, and harvest. At each time point, soil was sampled from five points per field (each point consisting of several soil cores) from 0-15, 15-30, and 30-60cm depths. Soil from the mid-season sampling was frozen and will be used for DNA amplicon-based sequencing to determine the soil bacterial and fungal community (based on 16S and ITS2 regions). We also analyzed soil samples for microbial biomass carbon and nitrogen to determine the abundance of the microbial community. Roots from lettuce plants were taken to estimate rates of arbuscular mycorrhizal colonization. We also collected measurements as indicators of ecosystem services including soil carbon sequestration, nutrient cycling, nitrogen retention, water conservation. To estimate the nutrient cycling ecosystem service, potential activities of the following soil C, N and P cycling enzymes were assessed glucanase, β-glucosidase, exochitinase, leucine-amino-peptidase, phosphatase, peroxidase, and phenol-oxidase. Soil inorganic nitrogen concentrations from lower depths at key points in the growing season will be used to assess potential for nitrogen retention. Intact soil cores were collected (140 in total) to determine complete soil water retention and hydraulic conductivity curves, which in turn will allow us to estimate soil properties related to water conservation. Soil samples for carbon stock calculations were taken using the equivalent soil mass method. Finally, lettuce was harvested to measure yields and plant nitrogen uptake.

Publications

  • Type: Journal Articles Status: Submitted Year Published: 2020 Citation: Tipping points in diversified farming systems. Authors: Melissa Chapman, Serge Wiltshire, Patrick Baur, Timothy Bowles, Liz Carlisle, Federico Castillo, Kenzo Eszquivel, Sasha Gennet, Alastair Iles, Daniel S. Karp, Claire Kremen, Jeffrey A. Liebert, Elissa M. Olimpi, Joanna Ory, Matthew Ryan, Amber R. Sciligo, Jennifer B. Thompson, Hannah Waterhouse, Carl Boettiger.
  • Type: Book Chapters Status: Under Review Year Published: 2020 Citation: Joanna Ory and Alastair Iles. (In review.) "Fostering Healthy Soils in California: Farmer Motivations and Barriers". In True Cost Accounting in Food, edited by Barbara Gemmill-Herren, Lauren Baker, and Paula Daniels (Springer).
  • Type: Journal Articles Status: Under Review Year Published: 2020 Citation: Petersen-Rockney, M., Baur, P., Guzman, A., Bender, S. F., Calo, A., Castillo, F., De Master, K., Dumont, A., Esquivel, K., Kremen, C., LaChance, J., Mooshammer, M., Ory, J., Price, M. J., Socolar, Y., Stanley, P., Iles, A., Bowles,. T. M. Adaptive capacity emerges from diversifying farming systems. Submitted to Frontiers in Sustainable Food Systems.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Bowles, T.M., Carlisle, L., Ory, J., Iles, A. Perceptions of cover cropping challenges and opportunities in California's complex socioeconomic and climate environment. California Plant-Soil Conference, Fresno, CA. (presentation)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Ory, J. Promoting Soil Health Innovations: Barriers, Motivations, and Enabling Conditions. California Resource Conservation District's (CARCD) 74TH Annual Conference. (presentation)
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Bowles, T.M. Soil health for productive and sustainable agriculture: Evidence and Barriers. NRCS Conservation Webinar series. Online.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Claire Kremen, C. Integrating social and ecological data to evaluate benefits and costs of diversified agroecosystems in California" Symposium on Agroecology with Communities: Cross-Disciplinary Collaborations Between Ecology, Agriculture and Social Science. Ecological Society of America, August 2019.