Rooted in Health: Benefits of Compost and Cover Crops to Soil Health in Nut Orchards in the Central Valley of California

Almond orchards in California, a cornerstone of the state's agricultural economy, face increasing pressures from climate change, compounded by the degraded condition of orchard soils. In my dissertation, I investigated the potential of sustainable management practices—specifically, compost and cover crops—to improve soil health. I found that soil carbon content in these orchards is greatly depleted, with significant variation compared to predicted values from soil survey maps. Variations in soil carbon stocks are driven by site-specific conditions and depth, underscoring the importance of deep soil sampling for accurate carbon estimation. In a four-year long field experiment, I demonstrate that integrating practices of compost and cover crops into conventional orchard management rapidly enhances soil health, leading to significant improvements in physical, chemical, and biological soil properties. These practices improve soil aggregation, boost plant-available nitrogen, and increase microbial activity. Furthermore, they foster beneficial shifts in bacterial and fungal communities, enhancing nutrient cycling and ecosystem stability. Depth-related variations in microbial communities emphasize the need to consider soil depth and management practices to optimize microbial-plant interactions. These findings demonstrate the role that ecological-based orchard management can play in sequestering carbon, restoring degraded soils, and enhancing agricultural resilience. 

Alexia is a PhD candidate in the Environmental Systems graduate group at UC Merced. She holds an M.S. in Environmental Management from Western Colorado University and a B.S. in Environmental Science from Westminster University. Before joining the Agroecology Lab at UC Merced, Alexia conducted research on perennial irrigated pasturelands, focusing on enhancing drought resilience and increasing carbon storage through compost amendments. Her research interests lie in exploring the complexity of soil systems across various agricultural landscapes, from urban to rural, with a particular emphasis on carbon dynamics.​