Optimizing residue and tillage management practices to improve soil carbon sequestration in a wheat–peanut rotation system

The sustainable development of agriculture has been challenged by the decline of soil quality and the change of climate. It is well known that soil carbon (C) sequestration plays crucial roles in improving soil structural stability, mitigating greenhouse emissions, and promoting plant nutrient supply. Therefore, a 3-year field experiment was conducted to evaluate the effects of different residue and tillage management practices on soil C sequestration in a wheat–peanut rotation system. Four treatments were studied: moldboard plow tillage with wheat residue returning (PTS), rotary tillage with wheat residue returning (RTS), no tillage with wheat residue mulching (NTS), and no tillage with wheat residue removal (NT). Our results indicated that residue return favored the improvement of soil C sequestration capacity relative to residue removal. In addition, NTS improved soil C sequestration in the surface soil layer (0–5 cm), but markedly reduced soil C sequestration in the deeper soil layers (5–30 cm). NTS thus caused a more obvious soil stratification phenomenon, which was not conducive to improving soil quality. At the 5–30 cm soil depths, the soil labile organic C fractions concentrations, carbon pool management index (CPMI), macroaggregates-associated C storage, intra-aggregate C fractions concentrations, and soil total organic carbon (TOC) storage under PTS were all higher than those under other treatments. Overall, a peanut strategic cultivation management mode that combines moldboard plow tillage and wheat residue return may be used as a reference for optimizing agricultural soil management to achieve the improvement of soil C sequestration capacity in a wheat–peanut rotation system.