The California Department of Food and Agriculture offers Healthy Soils Program demonstration project grants to fund on-farm projects that involve data collection, demonstrating various conservation management practices, and providing an opportunity for local growers to see the effectiveness of these practices through field days and workshops. Fortunately, the San Diego UCCE office received one of these grants.

The San Diego demo project will explore the effectiveness of compost application and cover cropping (CC) in tomatoes, and will be partnering with Valdivia Farm, located in Carlsbad, CA. Compost application, or a soil carbon amendment, can reduce the amount of synthetic fertilizer needed to be applied to a crop. Additionally, it improves soil organic matter, aids in carbon sequestration, improves soil aggregate stability and provides a habitat for soil organisms. In this demo project, compost with a C:N ration ≤ 11 will be applied at a rate of 4 tons/acre. Cover cropping has several benefits, including contributing to soil organic matter, reducing water runoff, reducing soil compaction and supplying nitrogen to the main cash crop. The cover crops that will be planted are Sudan grass (Sorghum × drummondii), Sunn hemp (Crotalaria juncea), and Brown mustard (Brassica juncea). Sudan grass is a summer annual grass that grows quickly, can aid in reducing soil compaction, and nematode suppression. Sunn hemp is a summer CC that also suppresses nematodes and as a legume, can fix nitrogen. Brown mustard is a cool-season CC that can aid in weed suppression and soil-born disease.

The demonstration project will take place for three years, and various soil metrics and crop yield data will be collected and analyzed. To learn more about the San Diego Healthy Soils Demonstration project, reach out to San Diego Community Education Specialist, Michael Jaquez (mtjaquez@ucanr.edu).

References

Compost Application Rate White Paper

National Resources Conservation Service Conservation Practice Standard: Soil Carbon Amendment

National Resources Conservation Service Conservation Practice Standard: Cover Crop

Sustainable Agriculture Research and Education Projects Website