Abstract. Mineral-organic associations are crucial carbon and nutrient reservoirs in soils. However, soil cultivation disrupts these associations, leading to carbon loss and reduced soil fertility. Although, identifying the specific type(s) of mineral-organic associations susceptible to destruction or transformation upon cropping remains challenging, it is essential for devising strategies to preserve organic matter in croplands. Here we aimed to determine the predominant mineral-organic associations and to identify which types of associations are transformed upon cultivation. To achieve this, we sampled an andosol from both a forested and a cultivated area. We then analyzed cultivation-induced changes in soil physicochemical parameters and characterized mineral-organic associations using an array of spectro-microscopic techniques (TEM-EDX, TEM-EELS, and STXM), for comprehensive structural and compositional analysis. At the micro and nanoscale, we observed mineral-organic associations in the form of coprecipitates composed of amorphous oligomers containing Al, Si, and Fe (referred to as nanoCLICs for nanosized coprecipitates of inorganic oligomers with organics). Down to a few hundred nanometers, the nanoCLICs displayed elemental enrichments with C+Al+Si, C+Fe+Al+Si, or Al+Si dominance with less C. In contrast, organic matter exhibited various C speciation without compound-specific enrichments. These findings suggest that mineral-organic associations in andosols are nanoCLICs-type coprecipitates rather than organic matter associated solely with secondary minerals. NanoCLICs were present in both forest and crop andosols, and while cropping led to a 50 % decrease in nanoCLICs, it did not alter their nature. This novel conceptualization of mineral-organic associations as nanoCLICs shifts our understanding of their persistence in andosols and demonstrates their vulnerability to crop-induced changes.

中文翻译：

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耕作减少了无定形共沉淀物形式的矿物-有机结合物的数量


摘要。矿物-有机组合是土壤中重要的碳和养分库。然而，土壤耕作破坏了这些关联，导致碳损失和土壤肥力降低。尽管识别在耕作时容易遭到破坏或转化的矿物-有机组合的具体类型仍然具有挑战性，但制定保护农田有机质的策略至关重要。在这里，我们的目的是确定主要的矿物-有机组合，并确定哪些类型的组合在种植过程中发生转变。为了实现这一目标，我们从森林和耕地采集了安度沙土样本。然后，我们使用一系列光谱显微镜技术（TEM-EDX、TEM-EELS 和 STXM）分析了耕作引起的土壤理化参数变化，并表征了矿物-有机关联，以进行全面的结构和成分分析。在微米和纳米尺度上，我们观察到由含有Al、Si和Fe的无定形低聚物组成的共沉淀物形式的矿物-有机缔合体（无机低聚物与有机物的纳米级共沉淀物称为nanoCLIC）。低至几百纳米，nanoCLIC 显示出以 C+Al+Si、C+Fe+Al+Si 或 Al+Si 为主的元素富集，而 C 较少。相比之下，有机物表现出各种 C 形态，而没有化合物特异性富集。这些发现表明，andosol 中的矿物-有机物是 nanoCLIC 型共沉淀物，而不是仅与次生矿物相关的有机物。 NanoCLIC 存在于森林和农作物和土壤中，虽然种植导致 nanoCLIC 减少 50%，但并没有改变其性质。 这种将矿物-有机关联作为纳米 CLIC 的新概念改变了我们对它们在安沙土中持久性的理解，并证明了它们对作物引起的变化的脆弱性。