Corn straw return to the field is a vital agronomic practice for increasing soil organic carbon (SOC) and its labile fractions, as well as soil aggregates and organic carbon (OC) associated with water-stable aggregates (WSA). Moreover, the labile SOC fractions play an important role in OC turnover and sequestration. The aims of this study were to determine how different corn straw returning modes affect the contents of labile SOC fractions and OC associated with WSA. Corn straw was returned in the following depths: (1) on undisturbed soil surface (NTS), (2) in the 0–10 cm soil depth (MTS), (3) in the 0–20 cm soil depth (CTS), and (4) no corn straw applied (CK). After five years (2014–2018), soil was sampled in the 0–20 and 20–40 cm depths to measure the water-extractable organic C (WEOC), permanganate oxidizable C (KMnO₄-C), light fraction organic C (LFOC), and WSA fractions. The results showed that compared with CK, corn straw amended soils (NTS, MTS and CTS) increased SOC content by 11.55%–16.58%, WEOC by 41.38%–51.42%, KMnO₄-C and LFOC by 29.84%–34.09% and 56.68%–65.36% in the 0–40 cm soil depth. The LFOC and KMnO₄-C were proved to be the most sensitive fractions to different corn straw returning modes. Compared with CK, soils amended with corn straw increased mean weight diameter by 24.24%–40.48% in the 0–20 cm soil depth. The NTS and MTS preserved more than 60.00% of OC in macro-aggregates compared with CK. No significant difference was found in corn yield across all corn straw returning modes throughout the study period, indicating that adoption of NTS and MTS would increase SOC content and improve soil structure, and would not decline crop production.

玉米秸秆还田是提高土壤有机碳（SOC）及其不稳定组分以及与水稳性团聚体（WSA）相关的土壤团聚体和有机碳（OC）的重要农艺实践。此外，不稳定的SOC组分在OC转换和隔离中起重要作用。这项研究的目的是确定不同的玉米秸秆还田方式如何影响与WSA相关的不稳定SOC组分和OC的含量。玉米秸秆返回的深度如下：（1）在未扰动的土壤表面（NTS），（2）在0–10 cm的土壤深度（MTS），（3）在0–20 cm的土壤深度（CTS）， （4）不使用玉米秸秆（CK）。五年（2014–2018年）后，在0–20和20–40 cm深度对土壤进行了采样，以测量水可萃取有机碳（WEOC），高锰酸盐可氧化C（KMnO ₄-C），轻质有机C（LFOC）和WSA馏分。结果表明，与CK相比，玉米秸秆改良土壤（NTS，MTS和CTS）使SOC含量增加11.55％–16.58％，WEOC增加41.38％–51.42％，KMnO ₄ -C和LFOC增加29.84％–34.09％， 0–40厘米土壤深度中为56.68％–65.36％。LFOC和KMnO ₄事实证明-C是对不同玉米秸秆还田方式最敏感的部分。与CK相比，玉米秸秆改良的土壤在0–20 cm的土壤深度中使平均体重直径增加了24.24％–40.48％。与CK相比，NTS和MTS在宏观聚集体中保留了60.00％以上的OC。在整个研究期间，在所有玉米秸秆还田方式中，玉米单产均无显着差异，这表明采用NTS和MTS会增加SOC含量并改​​善土壤结构，并且不会降低作物产量。