Erosion of the A horizon of Mollisols is expected to change the dissolved organic matter (DOM) chemodiversity in the underlying B horizon. Three simulated erosion treatments, which had an A horizon of 30, 20, and 10 cm depth, were established for 9 years under a corn-soybean rotation on Mollisols. Compared to the A horizon that was 30 cm deep, the 20 cm treatment had 24–63% more dissolved lignin-like compounds, a significant increase, in the 0–10, 10–20, and 20–30 cm layers of the B horizon. When the A horizon was 10 cm deep, 41% more lignin-like compounds accumulated in the 10–20 cm layer of the B horizon and 22% more lignin-like compounds were detected in the 20–30 cm layer of the B horizon. Relative to the A horizon of 30 cm depth, the 20 and 10 cm treatments reduced the lipid- and protein-like compounds by 69–87% in 10–20 and 20–30 cm layers of the B horizon layers. Labile compounds increased in the 0–10 cm layer of the B horizon but decreased in the 10–20 and 20–30 cm layers of the B horizon. The DOM degradation degree, expressed in terms of the degradation index and Gibbs free energy, were related to the lignin accumulation, indicating that lignin, a recalcitrant compound, was degraded. Notably, variations in DOM chemodiversity in eroded Mollisols were primarily controlled by soil physicochemical properties and not microbial traits. Therefore, eroded Mollisols have less carbon sequestration potential in the B horizon. To prevent soil deterioration in corn-soybean rotations, we recommend to incorporate a combination of organic and mineral fertiliser to a 20–30 cm soil depth in erosion-susceptible Mollisols.

中文翻译：

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模拟 A 层的侵蚀影响软质溶物中 B 层的可溶性有机质化学多样性和碳封存


预计软溶胶 A 层的侵蚀将改变底层 B 层的溶解有机物 （DOM） 化学多样性。在玉米-大豆轮作下，在 Mollisols 上建立了 30 、 20 和 10 cm 深度的 A 层 9 年的模拟侵蚀处理。与 30 cm 深的 A 层相比，20 cm 处理在 B 层的 0-10、10-20 和 20-30 cm 层中溶解的木质素样化合物增加了 24-63%，显著增加。当 A 层深 10 cm 时，在 B 层的 10-20 cm 层中积累的木质素样化合物增加了 41%，在 B 层的 20-30 cm 层中检测到的木质素样化合物增加了 22%。相对于 30 cm 深度的 A 层，20 cm 和 10 cm 处理将 B 层的 10-20 和 20-30 cm 层中的脂质和蛋白质样化合物减少了 69-87%。不稳定化合物在 B 层的 0-10 cm 层中增加，但在 B 层的 10-20 和 20-30 cm 层中减少。以降解指数和 Gibbs 自由能表示的 DOM 降解程度与木质素积累有关，表明木质素是一种顽固化合物，已被降解。值得注意的是，被侵蚀的软质溶胶中 DOM 化学多样性的变化主要受土壤理化性质而不是微生物性状的控制。因此，被侵蚀的软溶胶在 B 层中的固碳潜力较小。为了防止玉米-大豆轮作中的土壤恶化，我们建议在易受侵蚀的软溶胶中施用有机肥和矿物肥料，土壤深度为 20-30 厘米。