Dynamics in soil organic carbon of wheat-maize dominant cropping system in the North China Plain under tillage and residue management

A site experiment was conducted to assess temporal dynamics of soil organic carbon (SOC) and the drivers under no-tillage (NT) and residue retention (RR) in the North China Plain (NCP). The results indicated that NT and RR can significantly increase SOC up to a depth of 30 cm. On average, NT increased SOC by 8.1–34.5% compared with PT, and RR increased SOC by 3.5–14.4% compared with R0 at 0–10 cm. Increases in SOC under NT or RR could be increased by 4–10 percentage points through the significantly positive interactions of NT and RR. Among the sources of SOC variations, tillage-induced variations accounted for 74.4 and 44.3% of the total variations in SOC at 0–5 cm for wheat and maize season, respectively. Experimental duration was also a significant source of variation. Stepwise regression indicated dynamics in SOC at 0–5 cm mainly due to the positive effects of precipitation, the negative effects of soil bulk density for the wheat season, the negative effects of radiation for the maize season, and antagonistic effects of temperature between wheat and maize season. Generally, positive effects of NT and RR on SOC were both confirmed, but fluctuations and variations induced by interactions of practices and seasonal climatic conditions were also significant in the NCP. •Drivers of soil C dynamics under tillage and residue practices were assessed.•Spatial differences in responses of soil C to treatments were observed.•No-tillage and residue retention benefited surface and deep soil C, respectively.•Interactions of treatment and climate condition induced temporal changes in soil C.•Precipitation, radiation, and temperature caused seasonal changes in soil C.