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CDFA Healthy Soils Demonstration Project- Lake City, CA

This demonstration project looked at the potential of carbon sequestration and greenhouse gas (GHG) reduction attributable to grazing lands soil management practices. Between 2020-2024, within a grazed, irrigated grassland ecosystem we studied the effects of different compost application delivery methods on soil health and ecological function. To fully quantify the ranch effects, we measured soil carbon dioxide flux, nutritional availability in vegetation, soil organic carbon, crop yield, biological community (breeding birds), and the soil microbial community. We found that treatment did not influence measured CO2 fluxes, indicating compost may have stored additional carbon. Our data show no differences in yield nor forage quality between treatments, nor over the seasons. Fungal to bacterial ratios increased throughout the timeframe of the project, including in the control plot likely due to lower disturbance at the site. On average soil health metrics measured via the Haney test increased significantly over time, with the largest increase under the annual compost treatment. Due to the high variability of soil and vegetation across rangelands, the lack of change may simply be due to the use of only three replicates in the study design, and may warrant further monitoring, particularly as the producer anecdotally observed an increase in yield measurements over the study period.