Soil and crop characteristics are susceptible to straw-incorporation and can change considerably over time. These changes are likely to lead to variations in the soil structure, aggregate stability, and shear strength, thereby altering the soil erodibility. Currently, the temporal variation in the soil erodibility of sloping croplands affected by straw-incorporation rate (SIR) is unknown. The objectives of this study were to evaluate the temporal variation in soil erodibility using a comprehensive soil erodibility index (CSEI) with different SIRs, and to identify the dominant influencing factors in a small agricultural watershed in a semi-humid region. The CSEI was quantified using soil organic matter (SOM), K factor, structural stability index (SSI), slaking rate (SR), mean weight diameter (MWD), mean number of drop impacts (MND), soil cohesion (Coh), soil penetration resistance (PR), and saturated hydraulic conductivity (Ks). The results demonstrated that nine soil erodibility indicators exhibited different changes over time during each growing season. Over time, SOM, SSI, Coh, and PR increased, whereas Ks decreased. No distinct variation was observed in the K factor. The MND and MWD generally increased and then decreased over time, whereas the SR showed the opposite trend. Soil erodibility indicators were strongly affected by the SIR. MND, MWD, Ks, Coh, SSI, and SOM were positively correlated with SIR, whereas the K factor, PR, and SR were negatively correlated. CSEI under different SIR showed significant differences in fluctuations with temporal variation (p < 0.05). Compared to the control treatment, the mean CSEI was reduced by 21 %, 36 %, 40 %, 53 %, 66 %, and 56 % for straw-incorporation rates of 1.125, 2.25, 4.5, 6.75, 9, and 13.5 t hm−2, respectively. The main factors influencing temporal variation in the CSEI were aboveground biomass, root mass density, straw residual mass density (SRD), and straw decomposition amount (SD). The effects of SRD and SD on CSEI were the greatest at 60 d after straw incorporation. Thus, straw-incorporation can effectively reduce soil erosion. For semi-humid regions with high soil organic matter content, the optimal SIR was 9.0 t hm−2.

中文翻译：

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不同秸秆还田土壤可蚀性指标的时间变化


土壤和作物特性容易受到秸秆掺入的影响，并且会随着时间的推移而发生很大变化。这些变化可能导致土壤结构、团聚体稳定性和剪切强度发生变化，从而改变土壤的可腐蚀性。目前，受秸秆掺入率 （SIR） 影响的坡地土壤侵蚀性的时间变化尚不清楚。本研究的目的是使用具有不同 SIR 的综合土壤可蚀性指数 （CSEI） 评估土壤可蚀性的时间变化，并确定半湿润地区小型农业流域的主要影响因素。使用土壤有机质 （SOM） 、 K 因子 、结构稳定性指数 （SSI） 、崩解率 （SR） 、平均重量直径 （MWD） 、平均跌落冲击次数 （MND） 、土壤内聚力 （Coh） 、土壤渗透阻力 （PR） 和饱和水力传导率 （Ks） 量化 CSEI。结果表明，9 个土壤可蚀性指标在每个生长季节表现出不同的时间变化。随着时间的推移，SOM、SSI、Coh 和 PR 增加，而 Ks 下降。在 K 因子中未观察到明显变化。MND 和 MWD 通常随着时间的推移而增加然后下降，而 SR 则表现出相反的趋势。土壤可蚀性指标受 SIR 的强烈影响。MND 、 MWD 、 Ks 、 Coh 、 SSI 和 SOM 与 SIR 呈正相关，而 K 因子、 PR 和 SR 呈负相关。不同 SIR 下的 CSEI 显示随时间变化的波动存在显著差异 （p < 0.05）。与对照处理相比，秸秆掺入率分别为 1.125、2.25、4.5、6.75、9 和 13.5 t hm−2，平均 CSEI 降低了 21 %、36 %、40 %、53 %、66 % 和 56 %。 影响CSEI时间变化的主要因素是地上生物量、根质量密度、秸秆残余质量密度（SRD）和秸秆分解量（SD）。SRD 和 SD 对 CSEI 的影响在秸秆枺入后 60 d 最大。因此，秸秆掺入可以有效减少土壤侵蚀。对于土壤有机质含量高的半湿润地区，最佳 SIR 为 9.0 t hm−2。