Shifts in Carbon Stocks through Soil Profiles Following Management Change in Intensive Agricultural Systems

Soil carbon content is an important ecosystem property, especially under the ongoing climate change. The stability of soil organic matter (SOM) is controlled by environmental and biological factors including anthropogenic-induced agricultural management change. However, understand-ing the effects of anthropogenic activities (e.g., intensive agricultural practices) on carbon stability of soil profiles remains a challenge. The objective of this study was to determine the changes in carbon stocks through soil profiles following agricultural management change from grain fields to greenhouse vegetable fields. The sampling sites were located in an intensive vegetable production area in northern China. A total of 20 pairs of grain fields (GF) and adjacent vegetable fields (VF) within a distance of 50 m were selected. The results showed that soil organic carbon (SOC) storage increased by 10.6 mg C ha−1 in upper soil layers but decreased by 5.3 mg C hm2 in deeper soil lay-ers due to large input of organic manure and chemical fertilizer following the conversion from GF to VF. Conversion to VF also led to increased dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) concentrations. Extremely higher input of chemical N fertilizer in the VF led to th