Progress report for GW23-254
Project Information
Rangelands in California provide essential ecosystem services such as water purification, wildfire fire prevention, and food and fiber production. Rangelands also serve as the economic base of many rural communities. Because rangelands are rain-irrigated systems, these regions are vulnerable to drought conditions, which are expected to increase in severity due to climate change. Severe droughts pose significant threats to rangelands, including decreased livestock forage production, reduced biodiversity, and soil degradation. These ecological impacts also place significant socio-economic strain on ranchers. Previous initiatives have found that compost amendments provide benefits to soils and forage productivity within agricultural cropping systems, including greater resilience to drought. However, there are potential limitations to applying compost amendments to rangeland soils, and research thus far has demonstrated mixed results, particularly for soil health with key knowledge gaps remaining for the soil microbiome. It is essential to understand the ecological and social implications of compost application before implementing these practices on a large scale. This research will examine how compost application impacts soil microbial abundance and community composition on ranches. Soil microbes are essential in key processes that determine soil quality and health; soil health can, in turn, impact forage productivity and improve rangeland resilience to drought conditions. Throughout this project, I will work with ranchers and UCCE advisors to communicate results via on-ranch research and extension workshops. Project outcomes will be (1) determine impacts of compost applications to soil microbial ecology, (2) assess social barriers to adoption, and (3) collaborate and share results with stakeholders.
My overarching goal for this research is to determine the potential of rangeland compost application as a climate smart ranching practice to manage soils for increased resilience to prolonged drought and water scarcity in California.
Objective 1: Measure impacts of compost application to soil microbial biomass and community composition
I will work with ranchers and UC Cooperative Extension (UCCE) collaborators who have previously applied compost amendments to their land at a variety of sites managed under a gradient of livestock grazing intensities. Soil microbes are essential drivers of numerous soil processes (Wagg et al. 2021), and have previously been found to improve resilience to climate change induced drought and prolonged water scarcity (Umezawa et al. 2006). A primary objective of this work will therefore be to determine how compost amendments impact the soil microbiome. I will collect soil samples from each site to measure variation in total soil microbial biomass and microbial community composition between sites. I will then analyze these results to assess the potential impacts of compost application practices to the soil microbiome.
Objective 2: Determine potential of compost application to increase drought resilience in rangelands via key soil health metrics
There is substantial evidence that high soil microbial diversity, and microbial community composition impacts soil health metrics and large scale ecosystem processes (Wagg et al. 2021) Examining impacts of soil microbial diversity to key soil health metrics can potentially serve as a proxy for drought resilience. I will therefore analyze soil samples collected from all sites for key soil health metrics relevant to improving resilience to drought and increasing water uptake and retention. I will measure variation in soil organic matter, soil organic carbon, bulk density, and gravimetric water content, between sites. This will allow me to determine if variation in microbial abundance and community composition have an impact on soil health metrics.
Objective 3: Assess adaptive capacity and potential barriers to adopting compost application as a climate smart ranching practice
I will collaborate with UCCE advisors to create and distribute surveys in order to assess adaptive capacity of implementing compost amendment practices, as well as other potential climate smart ranching practices (e.g., prescribed burning, strip seeding, livestock species rotation). I will build on previously successful initiatives within my lab group using surveys to gauge rancher perspectives on barriers to adopting sustainable ranching practices(Roche et al. 2015). I will base these surveys on previously successful work applying the four key components of adaptive decision making: information sources, management capacity, goal setting, and previous experience (Lal et al. 2001).
Objective 4: Collaborate with and communicate results to ranchers, and key stakeholders
In order to facilitate project collaboration and communicate results to key stakeholders, I will leverage established relationships with UCCE professionals to provide workshops, demonstrations, and resources for ranchers in counties across California. This project will include collaborations with UCCE researchers who currently have partnerships with ranchers who have applied compost to their land, or have expressed interest in implementing composting practices on their land.
A no cost extension for this project (GW23-254) was approved on April 29th, 2025. The new project end date it December 31st, 2025. The approved project modification form, including the new timeline, is attachedProject Modification Form here.
Cooperators
- - Producer
- - Producer
- - Producer
Research
Project Sites: PT Ranch (Ione, CA) , Curran Ranch (Ione, CA), Dell’Orto Ranch (Jackson, CA), Brownlie Ranch (Jackson, CA)
Research Methods for Objective 1: Soil Microbial Analysis
To investigate how compost amendments affect soil microbial biomass and community structure, I collected 98 soil samples across four ranches in Amador County, California. This work was conducted in close collaboration with UC Cooperative Extension, which facilitated connections with local ranchers and supported site selection. The chosen ranches represent a gradient in elevation and soil productivity (low to high). Sampling locations built upon a previous Western SARE project (OW19-349), allowing for continuity and comparative analysis.
Soil sampling occurred between March and June 2024, coinciding with peak aboveground biomass to best capture seasonal microbial activity. At each site, soil was collected from plots representing four different treatments: 1) compost application only, 2) compost application and seeding mixture, 3) seeding only, 4) control (no compost or seeding). All samples were sent to Ward Laboratory in Kearney Nebraska and were analyzed for microbial biomass and diversity via PLFA (phospholipid fatty acid) analysis to estimate living soil microbial biomass, and analyzed for the presence of microbial functional groups (e.g., Andrews et al. 2024). To further assess the effects of compost and seeding on soil nutrient cycling, samples were also analyzed for soil enzymatic activity (e.g., Piotrowska-Długosz et al. 2022), providing insight into microbial-mediated nutrient supply processes.
Working with our collaborators, we recently completed the project database, which compiles pre- and post-treatment plant community data, management treatment information, and results of soil analyses. We are currently working with the project team to analyze how management treatments affect soil microbial abundance and composition across ranches, which span a range of ecological sites. We are using a variety of statistical tools, including analysis of variance, linear mixed models, and various multivariate methods (e.g., Principal Component Analysis), to determine variation in microbial ecology between sites, and the degree to which management drives changes in soil microbial ecology and soil health. A draft manuscript of these results, led by Ava-Rose Beech, will be completed by October 2025 and submitted for publication by December 2025.
Research Methods for Objective 2: Analysis of soil health metrics related to drought resilience
Sample collection and analysis for soil health metrics were completed in the summer of 2024 in partnership with our collaborators in the UC Davis California Soil Resources Laboratory. Statistical analyses of key soil health metrics– including soil organic matter, soil organic carbon, bulk density, gravimetric water content, aggregate stability, total NPK, MAOM, and POM– have been recently completed. These results will be synthesized and prepared for publication by fall 2025.
Additional next steps for this objective include analyzing how key soil health metrics (see above) vary based on soil microbial abundance and diversity at each site. I will conduct statistical analysis in R, using analysis of variance and linear mixed models, to assess the degree to which variation in soil health characteristics is related to microbial abundance, microbial diversity and management practices. This analysis will help determine whether soil microbial communities contribute to enhanced rangeland drought resilience, with soil health metrics related to water uptake and retention used as indicators of drought resilience. These results will be incorporated into and included in the manuscript outlined in Objective 1, and will be submitted for publication by December, 2025.
Research Methods for Objective 3, Assess rancher receptivity and barriers to adoption
Once I have completed data analysis and obtained results from this study, surveys will be used to assess rancher receptiveness towards adopting compost amendment practices in rangelands. I will collaborate with UCCE advisors to develop these surveys. This objective is based on previously successful initiatives using surveys to evaluate rancher decision making (Roche et al. 2016). Surveys topics will include: 1) assessment of ranchers’ interest in adopting compost application practices, 2) priority concerns from ranchers to adopting these practices, 3) evaluating rancher perspectives on the socioeconomic barriers of greatest importance to implementing compost application, and 4) assessing ranchers’ perspectives on the ecological and socioeconomic feasibility of implementing compost application practices. I will deliver surveys both electronically and via mail to reach as broad an audience as possible.
Surveys will be sent to ranchers once data and analysis have been completed for this project. Surveys will focus on gaining insights into rancher perspectives and reception to sustainable rangeland management practices, particularly in the context of weather extremes (e.g, drought). I will begin sending surveys to ranch managers in Amador, Plumas, Sierra, Yuba, and Butte Counties in Fall and Winter, 2024. will coordinate with UCCE partners to distribute surveys online via Qualtrics. Since receiving this Western SARE grant, I have completed my IRB application and SOW, and received IRB approval for the project (IRB ID No. 1995095-1).
In the fall and winter of 2025, I will assess adaptive capacity and rancher openness to sustainable rangeland management practices. Specifically, I will determine how different facets of ranching operations (e.g., geographic location, access to compost application resources, economic sustainability, rancher interest) impact barriers to adoption following Kachergis et al. (2014), and Lubell et al. (2018).
Research Methods for Objective 4, Collaborate with and communicate results to ranchers, and key stakeholders
Please see the Educational Outreach Plan below, for Objective 4 research methods. I will begin addressing objectives outlined in my Education and Outreach Plan, and sharing research results following statistical analysis in fall-winter of 2025.
References:
Bastida, F., Torres, I. F., Hernández, T., & García, C. (2017). The impacts of organic
amendments: Do they confer stability against drought on the soil microbial community? Soil Biology and Biochemistry, 113, 173–183.
Breshears, D. D., Knapp, A. K., Law, D. J., Smith, M. D., Twidwell, D., & Wonkka, C. L.
(2016). Rangeland Responses to Predicted Increases in Drought Extremity. Rangelands, 38(4), 191–196.
Buckley Biggs, N., Hafner, J., Mashiri, F. E., Huntsinger, L., & Lambin, E. F. (2021). Payments
for ecosystem services within the hybrid governance model: Evaluating policy alignment and complementarity on California rangelands. Ecology and Society, 26(1), art19.
Cusack, D. F., Kazanski, C. E., Hedgpeth, A., Chow, K., Cordeiro, A. L., Karpman, J., & Ryals,
R. (2021). Reducing climate impacts of beef production: A synthesis of life cycle assessments across management systems and global regions. Global Change Biology, 27(9), 1721–1736.
Dubey, R.K. et al. (2020). Methods for Exploring Soil Microbial Diversity. In:
Unraveling the Soil Microbiome. SpringerBriefs in Environmental Science. Springer, Cham.
Girden, E. R. (1992). ANOVA: Repeated measures. Sage.
Gravuer, K., Gennet, S., & Throop, H. L. (2019). Organic amendment additions to rangelands: A
meta‐analysis of multiple ecosystem outcomes. Global Change Biology, 25(3), 1152–1170.
Havstad, K.M., Peters, D.P.C., Skaggs, R., Brown, J., Bestelmeyer, B., Frederickson, E.,Herrick,
J., Wright, J., (2007). Ecological services to and from rangelands of the United States. Ecology Economics 64, 261–268.
Hogberg, P., Nordgren, A., Buchmann, N., Taylor, A.F.S., Ekblad, A., Hogberg, M.N. et
al. (2001). Large-scale forest girdling shows that current photosynthesis drives soil respiration. Nature, 411, 789–792.
Howitt, R.E.j, Medellín-Asuara, D., Macewan, J.R., Lund, Sumner, D.A. (2015).
Economic analysis of the 2015 drought for California agriculture. Davis, California, USA: Center for Watershed Sciences, University of California, Davis: p. ES-2, 12.
Kachergis, E., J. D. Derner, B. B. Cutts, L. M. Roche, V. T. Eviner, M. N. Lubell, and K. W. 7
Tate. (2014) . Increasing flexibility in rangeland management during drought. Ecosphere 5. 8.
Kuznetsova, A., P. B. Brockhoff, and R. H. B. Christensen (2017). lmerTest package:
Tests in linear mixed effects models. Journal of Statistical Software. 82:1–26.
Lal, P., H. Lim-Applegate, and M. Scoccimarro. (2001). The adaptive decision-making process as a tool for integrated natural resource management: focus, attitudes, and approach. Conservation Ecology 5(2): 11.
Lubell, M. N., Cutts, B. B., Roche, L. M., Hamilton, M., Derner, J. D., Kachergis, E., &
Tate, K. W. (2013). Conservation Program Participation and Adaptive Rangeland Decision-Making. Rangeland Ecology & Management, 66(6), 609–620.
Macon, D. K., Barry, S., Becchetti, T., Davy, J. S., Doran, M. P., Finzel, J. A., George, H.,
Harper, J. M., Huntsinger, L., Ingram, R. S., Lancaster, D. E., Larsen, R. E., Lewis, D. J., Lile, D. F., McDougald, N. K., Mashiri, F. E., Nader, G., Oneto, S. R., Stackhouse, J. W., &
Roche, L. M. (2016). Coping With Drought on California Rangelands. Rangelands, 38(4), 222–228.
McFarland, M. J., Vasquez, I. R., Vutran, M., Schmitz, M., & Brobst, R. B. (2010). Use of
Biosolids to Enhance Rangeland Forage Quality. Water Environment Research, 82(5), 455–461.
National Agricultural Statistics Service. California. California agricultural statistics, crop
year 2022. Available at: http://www.nass.usda.gov/Statistics_by_State/California/ Publications/California_Ag_Statistics/2012cas-ovw.pdf.Accessed 23 Nov 2022.
Pachauri, R.; Reisinger, A.; Barros, V.R.; Broome, J. (2014). Climate Change: Synthesis
Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. J. Roman. Stud. 2014, 4, 85–88.
Piotrowska-Długosz A., Długosz J., Frąc M., Gryta A., Breza-Boruta B. (2022). Enzymatic
activity and functional diversity of soil microorganisms along the soil profile – a matter of soil depth and soil-forming processes. Geoderma 416:115779.
Rillig, M.C. & Mummey, D.L. (2006). Mycorrhizas and soil structure. New Phytol., 171, 41–53.
Roche, L. M., Schohr, T. K., Derner, J. D., Lubell, M. N., Cutts, B. B., Kachergis, E.,
Eviner, V. T., & Tate, K. W. (2015). Sustaining Working Rangelands: Insights from Rancher Decision Making. Rangeland Ecology & Management, 68(5), 383–389.
Roche, L.M. (2016). Adaptive rangeland decision-making and coping with drought.
Sustainability. 8:1334. Rangelands, 38(4), 191–196.
Saitone, T.L. (2020). Chapter 9. Livestock and Rangeland in California. California Agriculture:
Dimensions and Issues. 207-223.
Umezawa, T.; Fujita, M.; Fujita, Y.; Yamaguchi-Shinozaki, K.; Shinozaki, K. (2006).
Engineering drought tolerance in plants: Discovering and tailoring genes to unlock the future. Curr. Opin. Biotechnol, 17, 113–122.
van der Heijden MGA, Bardgett RD, van Straalen NM. 2008. The unseen majority: soil
microbes as drivers of plant diversity and productivity in terrestrial ecosystems. Ecol. Lett, 11:296–310.
Wagg, C., Yann H., Pellkofer, S., Banerjee, S., Schmid, B., van der Heijden, M.A.,
(2021) Diversity and asynchrony in soil microbial communities stabilizes ecosystem functioning. eLife 10(62) 813.
Wang et al. (2007) Wang Q, Garrity GM, Tiedje JM, Cole JR. Naive Bayesian classifier for rapid
assignment of rRNA sequences into the new bacterial taxonomy. Applied and Environmental Microbiology. 2007;73(16):5261–5267.
Xiao F, Li Y, Li G, He Y, Lv X, Zhuang L, Pu X. (2021) . High throughput sequencing-based
analysis of the soil bacterial community structure and functions of Tamarix shrubs in the lower reaches of the Tarim River. PeerJ 9.
Yahdjian, L., Sala, O. E., & Havstad, K. M. (2015). Rangeland ecosystem services: Shifting focus from supply to reconciling supply and demand. Frontiers in Ecology and the Environment, 13(1), 44–51.
Objective 1: Measure impacts of compost application to soil microbial biomass and community composition
Soil sample collection and all soil microbial analysis was completed last June, 2024. Statistical analysis of soil microbial data analysis is currently in progress, with completion expected by August 2025. Results will be written up for publication by late Winter, 2025.
Objective 2: Determine potential of compost application to increase drought resilience in rangelands via key soil health metrics
Field work and all soil analysis of key soil health metrics was completed last June, 2024. Additionally, preliminary results indicate that differences in ecological site characteristics, including elevation and soil morphology, influence the effects of compost applications (California Soil Resources Lab, In prep). Higher elevation sites exhibited the greatest increases in soil carbon and nitrogen, as compared to lower elevation sites.
Objective 3: Assess adaptive capacity and potential barriers to adopting compost application as a climate smart ranching practice
The analysis of results for objective 3 (assessing adaptive capacity and identifying potential barriers to adoption) will be completed following the conclusion of extension workshops and the distribution and collection of surveys in fall and winter 2025.
Objective 4: Collaborate with and communicate results to ranchers, and key stakeholders
As of May, 2025, we have shared preliminary results and project updates with a range of stakeholders at multiple outreach and extension events, including the Western SARE CAPS Summit, the UC Davis Institute for the Environment Symposium, the California Native Grassland Association seminar series, the Society for Range Management Annual Meeting (posters and presentations presented by Ava-Rose Beech), and the California Rangeland Conservation Coalition (poster presented by Alyssa Flores).
We also collectively presented results from this project at the Rustici Rangeland Science Symposium. Dr. Anthony O’Geen presented one keynote talk on this research. Ava-Rose Beech and Alyssa Flores presented research posters. We will be hosting additional outreach and extension education events, and presenting at conferences during fall and winter of 2025.
Research Outcomes
Recommendations for sustainable rangeland management practices informed by this project will be made once all data analyses have been completed . Additionally, recommendations from this work will be based on analysis of surveys for rancher receptiveness and barriers to adoption. Once data analysis has been completed, recommendations will be made based on how compost and seeding practices alter soil microbial community composition and soil health metrics, as well as rancher receptiveness to adopting these practices.
Education and Outreach
Participation Summary:
Following soil microbial data analysis, I will communicate all results and key findings from this project with stakeholders. I will synthesize the data from this work to make it clear, accessible, and easy to reference. All event planning and preparation will be finalized by December, 2025. I will prepare for these outreach efforts based on the timeline below.
July-August 2025: Begin initial planning of extension workshops and developing materials for outreach events for ranchers and local community members.
September- October 2025: Work with UC Cooperative Extension partners, and collaborators in the California Soil Resources Laboratory to coordinate extension events. This includes preparing all materials, creating informational pamphlets and handouts, and setting dates and locations for extension events.
November-December 2025: Finalize all details for extension events. Print and prepare materials, finalize all event logistics, materials, and agendas. Send out advertisements for the event, schedules, and agendas.
In collaboration with Cooperative Extension, we will coordinate two extension events to share results from this project with a range of stakeholders . The itinerary for these events will include: (1) Overview of the data and results from this study, and implications of these results for ecological and economic sustainability, (2) break out sessions for ranchers to discuss and develop protocols for integrating sustainable rangeland management practices into their management regimes that maintain economic sustainability, (3) Open forum style Q & A, and discussion of the results and adaptive capacity to apply sustainable rangeland management, and (4) Social and networking opportunities for ranchers interested in sustainable rangeland management practices to connect and share ideas.
All participants will receive (1) a one-page, synthesized summary of key results from this study, (2) a one-page resource sheet containing information with resources to find further information about compost application practices, other groups currently investigating compost application practices (e.g., The Working Lands Innovation Center, CalCal Healthy Soils initiative), and access to information about other sustainable rangeland management practices (e.g., prescribed burning, strip seeding). Information on these handouts will also be uploaded to the UC Rangelands Research and Information Center, which receives ~2K page views/month from 160 countries around the world. Preceding these extension workshops, ranchers will be sent follow-up surveys to determine the efficacy of the information and resources provided, and areas for improvement at future outreach events.
Additionally, we will work with partners such as California Cattlemen’s Association, state and federal agency partners, and nonprofits to provide outreach via legislative bulletins, newsletters, and trade magazines (e.g., Progressive Cattleman). We will develop presentation materials to share at producer meetings (California Cattlemen’s Association & Cattle Women's Inc Convention), local UCCE workshops, and professional and scientific meetings (e.g., Society for Range Management).
Lastly, I will collaborate with ranchers involved in this research and UCCE advisors to create presentation materials to share at producer meetings, local UCCE workshops, and professional and scientific meetings (e.g., Society for Range Management) for land owners, land managers, and NGO staff. Preliminary results from these research have already been shared at multiple professional and scientific meetings, as detailed in the participation summary. I will also develop a non-academic article that will be published in an advisor newsletter to clientele. I will communicate the results of this research, and provide information about goals and future directions for research related to soil health and drought resilience in California.
Participation Summary:
We have already shared preliminary results and project updates with a range of stakeholders at multiple outreach and extension events, including the Western SARE CAPS Summit, the UC Davis Institute for the Environment Symposium, the California Native Grassland Association seminar series, the Society for Range Management Annual Meeting, the California Rangeland Conservation Coalition.
We also collectively presented results from this project at the 2025 Rustici Rangeland Science Symposium. Dr. Anthony O’Geen presented a keynote talk on this research, and Ava-Rose Beech and Alyssa Flores presented research posters. We will be hosting additional outreach and extension education events as noted below.
Additionally, ranchers have been actively involved in the research since its inception, due to the on-ranch nature of the project.