Both iron (Fe) oxide and soil organic carbon (SOC) content, among other factors, drive the development and subsequent stability of soil aggregates. However, the mechanism of these drivers in paddy-upland rotation systems with straw residue incorporation is not well understood. In this multiyear (2011–2017) trial, we sought to study the factors which drive the stability of soil aggregates in such a rice-rape (RR) agronomic system. In order to examine the effect of straw residue incorporation and potassium fertilization on soil aggregation dynamics, we divided our trial into four treatments: inorganic phosphorus (P) and nitrogen (N) fertilizer; inorganic NPK fertilizer; inorganic NP fertilizer plus straw residue; and inorganic NPK fertilizer plus straw residue. Treatments which incorporated straw residue significantly increased both the geometric mean diameter (GMD) and the mean weight diameter (MWD) of soil aggregates. Soil aggregate stability was greater after rape harvest than after rice harvest, while SOC shows the opposite trend. Straw residue incorporation increased the SOC and, specifically, concentrations of aliphatic-C and aromatic-C, particularly in aggregates greater than 0.25 mm. Straw residue addition significantly increased both the amorphous (Feo) and complex iron oxide (Fep) contents of soil. In both bulk soil and in aggregates greater than 5 mm, SOC and Fep were positively correlated with MWD, while in aggregates less than 5 mm, Feo was positively correlated with MWD. Overall, we suggest that the increased concentrations of SOC, alkane-C, Feo, and Fep in soils after incorporation of straw residue were responsible for increasing soil aggregate stability.

中文翻译：

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秸秆混入和施钾通过改变水稻-油菜种植系统中氧化铁和有机碳的土壤含量来提高土壤团聚体稳定性

除其他因素外，铁 (Fe) 氧化物和土壤有机碳 (SOC) 含量都推动了土壤团聚体的发展和随后的稳定性。然而，这些驱动因素在稻草 - 旱地轮作系统中与秸秆混合的机制尚不清楚。在这项多年期（2011-2017 年）试验中，我们试图研究在这种水稻油菜（RR）农艺系统中驱动土壤团聚体稳定性的因素。为了检验秸秆还田和施钾肥对土壤团聚动力学的影响，我们将试验分为四种处理：无机磷（P）和氮（N）肥；无机氮磷钾肥；无机氮肥加秸秆渣；无机氮磷钾肥加秸秆渣。加入秸秆残渣的处理显着增加了土壤团聚体的几何平均直径 (GMD) 和平均重量直径 (MWD)。油菜收获后土壤团聚体稳定性高于水稻收获后，而土壤有机碳则呈现相反的趋势。秸秆残渣的掺入增加了 SOC，特别是脂肪族 C 和芳香族 C 的浓度，特别是在大于 0.25 mm 的聚集体中。秸秆残渣的添加显着增加了土壤的无定形 (Feo) 和复合氧化铁 (Fep) 含量。在块状土壤和大于 5 mm 的团聚体中，SOC 和 Fep 与 MWD 呈正相关，而在小于 5 mm 的团聚体中，Feo 与 MWD 呈正相关。总体而言，我们建议 SOC、烷烃-C、Feo、