The effects of compost application on grazed grasslands' greenhouse gas budget, water budget, net primary productivity, and microbial communities

Compost application has great potentials for facilitating soil carbon sequestration through the direct input of organic carbon and biomass increment via enhanced photosynthesis. Compost application also modulates the ecosystem water cycling by increasing water infiltration and holding capacity, while decreasing water losses via evapotranspiration. Yet, there is limited observation of carbon and water cycles before and after the compost application to support our quantitative predictability. This pioneer study is part of the Working Lands Innovation Center (WLIC) effort to scale, sustain, and quantify carbon dioxide capture and greenhouse gas emissions reductions by deploying soil amendments on a wide range of Californian agroecosystems. This study aims to understand and quantify the effects of one-time compost application on grazed annual grasslands' greenhouse gas budget, water budget, and microbial communities. We utilize multiscale measurements ranging from the eddy covariance flux tower, chamber measurements to lab and field experiments to quantify the scale-emergent properties like the net ecosystem exchange of CO₂ and water vapor, microbial and plant communities, soil carbon, soil water infiltration. This work will present the results from the first several months of measurements as a baseline of the grassland's carbon and water budget prior to the compost application. Specifically, we will show how changes in temperature, rainfall, and other environmental factors influence the greenhouse gas budget of the grazed grassland. The data collected is critical to updating the California natural and working LANDs model, a major goal of the WLIC project.