CalCAN Summit 2022: Insights from the Healthy Soils Science Workshop

Posted on Wednesday, November 23rd, 2022 by Anna Larson
Little Gem Farm, located at the Center for Land-Based Learning, was the first stop at our pre-Summit Farm Tour.

Recap from the Healthy Soils Science Workshop

At CalCAN’s 7th California Climate & Agriculture Summit, we heard from a panel of three healthy soils experts moderated by Nina Ichikawa, Executive Director of the Berkeley Food Institute, in a packed workshop session. Each researcher presented on a different aspect of healthy soils, but the overall message was clear: soil health practices provide important benefits that vary depending on local context and farm management, and we need to take a nuanced, place-based approach.

Jessica Chiartas, a postdoctoral scholar at UC Davis, shared her research on hedgerows as a promising practice that could provide carbon sequestration benefits in addition to important co-benefits across a range of soil types and/or textures. Toby O’Geen, Professor and Soil Resource Specialist in Cooperative Extension at UC Davis, shared his work illustrating how the effects of soil health practices will vary depending on a farm’s soil health region within California. Tim Bowles, Assistant Professor of Agroecology and Sustainable Food Systems at UC Berkeley, shared his work examining strategies to better integrate management for soil health and efficient water use. All three emphasized the need for a regional and context-based approach to healthy soils management.

Jessica explained that hedgerows provide ground cover and native habitat for pollinators and beneficial insects, and can have an outsize impact on farm carbon sequestration as hedgerows keep roots in the ground all year long. Jessica estimates that hedgerows on farm edges have the potential to increase farm carbon sequestration potential by an additional 50 to 100 percent, and if 50 percent of California farms installed hedgerows on their farm edges, they could sequester 10.8 million metric tons of carbon dioxide equivalent after approximately 10 years from establishment. Her major takeaway is that hedgerows are low hanging fruit: they sequester carbon, are relatively easy to implement, and provide many co-benefits and ecosystem services. 

A slide from Jessica’s presentation that shows the carbon sequestered at different soil sampling depths in hedgerows and cultivated fields in her study.

Toby’s work divides California’s croplands into seven distinct soil health regions. Oftentimes, soil health studies observe different outcomes under the same agricultural practices. Toby’s research suggests that these discrepancies in outcomes are linked to soil differences, meaning different soil health regions will respond differently to soil health practices. Importantly, combining practices often resulted in the greatest increase in soil organic matter across the soil health regions. His major takeaway: we need to take a place-based approach to healthy soils practices that considers local context. 

A slide from Toby’s talk illustrating the classification system his research team created for seven different soil health regions in California croplands.

Tim shared his work on the complex relationship between soil health and water, with strategies to better integrate management approaches. Unlike other agricultural regions in the U.S., California has a mediterranean climate with little precipitation and a long dry season. These factors mean it is more challenging to build soil organic matter (SOM), and that building SOM may not necessarily increase water storage unless soil health strategies are paired with irrigation management.  To effectively manage soil health and water interactions in California, we need to take a nuanced approach that 1) enables reduced irrigation, 2) reduces crop water stress and 3) facilitates groundwater recharge. His major takeaway: we need integrated soil health-water management strategies that take a regional approach. 

A slide from Tim’s presentation illustrating a conceptual framework for outcomes of soil health management for water resources. Original artwork by Elena Harley ( Acevedo et al. (in press).

In the moderated discussion and audience Q&A that followed, several themes emerged. There is a need for funding for long-term experiments on farms, including research that implements deficit irrigation trials across soil health gradients and regional monitoring across the state to understand the effects of a single practice across a range of soils. Additionally, to understand the impacts of soil health practices, we need to measure biodiversity, water, impacts on profitability, and other ecosystem services, in addition to carbon sequestration. Relatedly, policymakers should take an integrated approach to healthy soils and consider opportunities to think about soil health in other relevant state arenas, such as implementation of the Sustainable Groundwater Management Act and the Irrigated Lands Regulatory Program. Lastly, the panel emphasized the need for context-specific farm planning that helps farmers identify and implement soil health practices that will work well for their operation and region. As Toby summarized, “Mother nature didn’t create soils for simple policies. We have to dive deep and put a regional context on it.”

Further Resources from Panel Speakers

Soil Life – Educational resource on healthy soils

California Soil Resource Lab – Decision-making tools

BFI Policy Brief: Connecting Soil Health and Water in California

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