Effects of Returning Organic Wastes on the Stability of Soil Aggregates and Organic Carbon at Different Soil Depths

The processes of soil aggregates formation and stabilization play a crucial role in determining the sequestration of soil organic carbon (SOC), and organic wastes (OW) amendment is an effective measure for achieving more sustainable agriculture. However, the changes in soil aggregates and SOC in response to straw combined with differential animal manure remain elusive. Herein, this study investigated the effects of the four treatments (CK-no organic wastes; MS-maize straw only; OS-ox manure plus maize straw; CS- chicken manure plus maize straw) on soil aggregates and SOC of different sizes at different soil depths. Compared with the CK, the macroaggregates (SMAs) contents corresponding to CS-, OS-, and MS-treated soils were 15, 12, 2% at the 0-10 cm soil depth. In the 10-20 cm soil layer, the MWD and GWD in CS treatment were higher than that of CK. Moreover, OW treatments provide better accumulation of the SOC contents in megaaggregates (LMAs) and SMAs. The contribution rate of SOC of LMAs and SMAs aggregates in CS and OS increased than in the MS and CK. This indicated that manure and straw (especially maize straw plus chicken manure) help to sustain the stability of soil aggregates and SOC sequestration.