Meet Krista Marshall
My name is Krista Marshall, and I’m a recent graduate from UC Davis that is interested in topics around Agroecological design and management, soil ecology, and perennial orchard systems. Specifically, my research focused on exploring the relationships between soil health building principles, soil ecosystem functional outcomes, and multifunctionality in almond orchards.
Can you give us an overview of your research?
My research focuses on using a principally-based approach to answer questions about the relationships between soil health management and soil ecosystem functional outcomes in perennial systems. With funding from the Almond Board of California, we built a collaborative on-farm project between UC ANR, UC researchers, and farmers across a range of operation scale and farm goals to answer these questions. Rather than document the practices, we described management in each orchard we worked in by principles such as presence of living plant covers, extent of soil cover, physical disturbances, quantity and types of organic matter, and strategies to increase biodiversity.
What are the major take-aways from the project?
What we found was that a stacked application of these principles (i.e. many principles applied simultaneously) may be essential to improving soil ecosystem functionality in California’s perennial agroecosystems. Orchards that maximized the presence of diverse plant living covers and integrated extensive, rotational grazing showed the greatest potential for high levels of soil ecosystems functioning. Specifically, these orchards had the highest indicators of the soil’s ability to build soil carbon, regulate soil fertility, and support diverse and active soil communities. Mean values for soil organic carbon and total nitrogen were between 1.4 and 2.9 times higher than the other orchards in the study with no animal integration.
Did any of the results surprise you?
The most surprising result from our study was that orchards that applied organic amendments alone or with plant winter cover crops did not differentiate from bare soil management in their measured indicators of soil ecosystem functions. They consistently had the lowest potential to build soil carbon, reduce compaction, regulate soil fertility, and support soil communities. While these management strategies are increasing in popularity and financial support by government agencies, I think our work suggests we may need to do more research to explore the capacity of and conditions in which these practices may improve soil health.
