Influences of soil properties and hydrological processes on soil carbon dynamics in the cropland of North China Plain

•SIC stock was positively correlated with SOC stock with soil pH > 7.8.•SOC was significantly lower in the subsoils of Fluvo-aquic near the Yellow River.•WEOC:SOC ratio was significantly higher in the subsoils of Fluvo-aquic.•The low SOC near the Yellow River may be associated with hydrological processes.