Soil organic carbon saturation deficit under primary agricultural managements across major croplands in China

ABSTRACTIntroduction: To generate information for the effective management of soil organic carbon (SOC) sequestration in Chinese croplands, we compared the additional organic carbon (C) that can be stabilized by fine soil particles (<20 μm) with typical fertilization practices across soil types and climate zones. Using data from 30 long-term experimental study sites across the major agricultural zones in China, we estimated stable SOC saturation deficit (SOCdeficit) under no fertilization (CK), chemical fertilization (CF), straw plus CF (S + CF), and manure plus CF (M + CF). Stable SOCdeficit was defined as the difference between potential and current SOC stabilized by fine soil particles. Outcomes: Stable SOCdeficit values varied from 51% to 82%. Soils dominated by 2:1 clay minerals showed larger stable SOCdeficit than soils dominated by 1:1 clay minerals under each treatment. For soils dominated by 2:1 clay minerals, stable SOCdeficit was significantly lower under M + CF (69%) than under CK, CF, and S +...