Soil organic carbon increased after 3 years in organic grain systems differing in tillage and organic inputs

Organic grain systems can enhance soil organic carbon (SOC), but tillage may limit SOC gain, particularly in humid subtropical regions. We measured active and total SOC pools to 60 cm after 3 years in four organic grain systems differing in tillage and fertility. SOC stocks increased 30.3%–38.6% from baseline across depths, yet total SOC did not differ among cropping systems despite contrasting C inputs (9.4–22.2 Mg ha −1 ). At 0–5 cm, active C pools were the highest in the Ecologically Conscious System (ECS) characterized by reduced tillage, extended cover cropping, and C inputs of 18.5 Mg ha −1 . Compared with the intensively tilled Maximum Yield System receiving 22.2 Mg C ha −1 , ECS had 10.8%, 24.9%, and 28.5% higher permanganate‐oxidizable C, water‐extractable C, and microbial biomass C, respectively. These findings suggest that adjusting tillage and fertility strategies can promote early active C gains that may support long‐term SOC accumulation.