Soil Biodiversity and California Agriculture: A Landmark study for California and the USA

By Dr. Daniel rath, USA- Natural resources defense council, and Dr. kate Scow, USA - University of california davis

Satellite image of the Central Valley of California

The capacity of global agricultural systems to help provide solutions to climate change and biodiversity loss hinges on soil biodiversity. The vast, interconnected network of soil organisms beneath our feet is estimated to hold more than half of the world’s remaining biodiversity. This living network winds through the soil like golden threads in a tapestry, and is (simultaneously!) responsible for regulating greenhouse gasses, providing nutrients and energy to our crops, helping store water and reduce flooding, suppressing pathogens, and much more. This multifunctional nature of soil biodiversity emerges from their numerous connections and interactions – between symbionts, between parasites and hosts, and between predators and prey. Given this complexity and soil’s extraordinary diversity, a recent report commissioned by the California Department of Food and Agriculture provides guidance for how protecting soil functions requires us to consider soil biodiversity from a whole-system perspective.

And protecting soil biodiversity is necessary! Soil biodiversity faces major threats from human activities and global change, including land use change, increased human disturbance, climate change, pollution, invasive species, overexploitation, and loss of habitat connectivity. These threats disrupt soil biological networks, impair ecosystem functions, degrade soil structure and fertility and reduce ecosystem resilience. In the next few decades, soil biodiversity faces the immediate threat of extreme weather events, further land use conversion, and increased disturbance and pollution. If these more immediate threats are not addressed, these soils will be unable to handle the more gradual threats of longer and more active fire seasons, changing rainfall and increased temperatures due to climate change.

A nematode wrapped around a plant root. Photo Credit: Mara Johnson, Scow Lab

Historically sidelined in broader biodiversity conservation efforts, soil biodiversity is now gaining recognition. Restoring, maintaining and enhancing soil health and biodiversity is a target in the new Kunming-Montreal Global Biodiversity Framework, while protecting soil biodiversity is a key deliverable of the EU biodiversity strategy for 2030 and a major focus of the proposed EU Soil Health Law. In the USA, a recent report out of California’s Department of Food and Agriculture –: Soil Biodiversity in California Agriculture: Framework and Indicators for Soil Health Assessment –builds on the momentum around healthy soils by being the first US report to outline a strategy for how to measure and monitor soil biodiversity in agroecosystems. The report also outlines recommendations for how to integrate soil biodiversity into existing and future state programs.

The report, a collaborative effort among California soil scientists and microbiologists, addresses the challenge of selecting appropriate soil biodiversity indicators and methods, and proposes a versatile framework attuned to stakeholder input and expert insights. Inclusion of four example “use-cases” in the report demonstrates the adaptability of the framework, with recommendations for how to integrate soil biodiversity monitoring into established soil health and conservation initiatives. The report concludes by recommending that monitoring of soil be included in the California’s Healthy Soil programs, and expanded to other state and federal initiatives such as the 30x30 Biodiversity Initiative - a global initiative to conserve 30 percent of the globe’s lands and coastal waters by 2030.

Confronting simultaneous crises in biodiversity loss, climate change, and public health by building on the synergy between human health and soil health can lead to creative solutions. By promoting sustainable land management, embracing the principles of agroecology, and elevating belowground biodiversity to its deserved prominence, we can ensure the preservation and regeneration of our soils. For soil to continue to play roles in providing essential ecosystem services, it is crucial that we recognize and preserve life belowground and ensure that our healthy, living soils get the protection they deserve.