What does it mean to have healthy soil, and how can farmers monitor and improve the soil health in their fields?
These were some of the questions discussed by farmers and other ag professionals, UC Davis scientists and members of the public in a highly engaging public field day organized and led by UC Davis researchers Nicole Tautges, Sonja Brodt, Radomir Schmidt and Xia Zhu-Barker at the Russell Ranch Agricultural Research Facility on December 12th. Field day participants were given an overview of research currently under way at Russell Ranch, particularly highlighting the Healthy Soils Project funded by the California Department of Food and Agriculture (CDFA). The Healthy Soils Project started in the Fall of 2018, and is located at Russell Ranch and a nearby commercial farm. The research component of this project is aimed at increasing our knowledge base about what happens when mineral fertilizer application is amended with compost and/or cover crops. Specifically, the project will demonstrate the effects of supplementing mineral fertilizers with either composted chicken manure or composted green waste plus/minus cover crops on soil greenhouse gas emissions. Although these practices have been shown to lead to improvements in soil quality in the past, more work is necessary to more fully understand how different versions of these practices affect soil development and maintenance, and what specific changes take place during the initial transition period from a standard conventional farming system to a system employing these additional, selected conservation practices.
Following the introductory session participants broke into smaller groups for a discussion centered on farming successes observed with conservation practices, implementation issues, and possible solutions. The discussion brought to the fore the importance of continuing soil education. Farmers wanted to know the specifics of conservation practice mechanics in order to maximize benefits for their soils and their operations. They also talked about the need for innovative approaches to implementing soil building practices, such as planting cover crops, in ways that avoid disturbing the soil and creating compaction. Those on the science side cherished the opportunity to listen and learn from those on the ground, to make sure their research is anchored in the real-world; hearing first-hand what farmers are seeing on their fields, as well as the logistics of adopting specific practices.
Nicole Tautges kicked off the final, practical portion of the field day with a popular, informative summary of soil carbon analysis - where, when and how to sample, things to look for in a soil testing lab, and how to interpret the results and use them to keep track of long-term soil development. Radomir Schmidt then went over the importance of soil aggregation and soil structure for soil functioning, particularly water infiltration, retention and filtering, and demonstrated simple tests as well laboratory methods for soil aggregate analysis. Xia Zhu-Barker rounded off the section with a description of soil microbial community activity that leads to the production of various gases, including greenhouse gases affecting our changing climate, demonstrated the measurement of the gas efflux from soil, and described what it tells us about the activity of the soil microbial community. Together, these three measures - soil carbon, aggregates and gas efflux - tell us how rich a soil is, what its structure is and how active the microbial community is, respectively. These are all essential aspects of soil heath.
The field day participants left with some new knowledge, but perhaps more importantly an affirmation that dialogue between farmers, researchers and all other stakeholders is essential in order to optimize our farming systems to produce good crops while they cultivate, sustain and protect our precious soils.