Hedgerows on Crop Field Edges Increase Soil Carbon to a Depth of 1 meter

Effective incentivization of soil carbon (C) storage as a climate mitigation strategy necessitates an improved understanding of management impacts on working farms. Using a regional survey on intensively managed farms, soil organic carbon (SOC) concentrations and stocks (0–100 cm) were evaluated in a pairwise comparison of long-term (10+ years) woody hedgerow plantings and adjacent crop fields in Yolo County, CA, USA. Twenty-one paired sites were selected to represent four soil types (Yolo silt loam, Brentwood clay loam, Capay silty clay, and Corning loam), with textures ranging from 16% to 51% clay. Soil C was higher in the upper 100 cm under hedgerows (14.4 kg m⁻²) relative to cultivated fields (10.6 kg m⁻²) and at all depths (0–10, 10–20, 20–50, 50–75, and 75–100 cm). The difference in SOC (3.8 kg m⁻²) did not vary by soil type, suggesting a broad potential for hedgerows to increase SOC stocks. Assuming adoption rates of 50 to 80% across California for hypothetical field edges of average-size farms, and an identical SOC sequestration potential across soil types, hedgerows could sequester 10.8 to 17.3 MMT CO₂e, or 7 to 12% of California’s annual greenhouse gas reduction goals.