Soil organic carbon and nitrogen responses to cover crops in Norfolk soil under long‐term contrasting tillage systems

Abstract Cover crops have garnered increased attention as a conservation strategy to increase soil organic carbon (SOC) and nitrogen (N) while improving overall soil health in agricultural systems. However, their effect on SOC and N dynamics in sandy soils of the US southeastern (SE) Coastal Plain is poorly understood. This study evaluated the response of SOC and N pools to cover crops in a Norfolk loamy sand under long‐term (>40 years) conventional (CvT) and conservation (CnT) tillage systems and short‐term (5 years) winter cover cropping. Treatments included: Tillage (two levels: CvT and CnT) crossed with winter cover crops (two levels: cover crop and fallow) in a factorial design. Soil samples were collected from each treatment in spring and fall 2022–2024, and analyzed for soil pH, electrical conductivity, total SOC and soil total nitrogen (STN), dissolved organic carbon (DOC), hot water‐extractable carbon (HWEC), microbial biomass carbon (MBC), inorganic N, and potentially mineralizable nitrogen (PMN). The CnT increased total SOC and STN by 64% and 72%, and DOC and HWEC by 22% and 52% over CvT, respectively. There were measurable, yet modest, improvements in SOC and N fractions with cover crops, suggesting ecosystem enhancement services were underway, albeit modest at this stage. Our results demonstrated that cover cropping should be considered a long‐term conservation strategy to gradually improve soil health and productivity, not as a “quick fix” for low‐fertility soils in the SE Coastal Plain.