Correlations between organic carbon (OC) and fine mineral particles corroborate the important role of the abundance of soil minerals with reactive surfaces to bind and increase the persistence of organic matter (OM). The storage of OM broadly consists of particulate and mineral-associated forms. Correlative studies on the impact of fine mineral soil particles on OM storage mostly combined data from differing sites potentially confounded by other environmental factors. Here, we analyzed OM storage in a soil clay content gradient of 5–37% with similar farm management and mineral composition. Throughout the clay gradient, soils contained 14 mg OC g⁻¹ on average in the bulk soil without showing any systematic increase. Density fractionation revealed that a greater proportion of OC was stored as occluded particulate OM in the high clay soils (18–37% clay). In low clay soils (5–18% clay), the fine mineral-associated fractions had up to two times higher OC contents than high clay soils. Specific surface area measurements revealed that more mineral-associated OM was related to higher OC loading. This suggests that there is a potentially thicker accrual of more OM at the same mineral surface area within fine fractions of the low clay soils. With increasing clay content, OM storage forms contained more particulate OC and mineral-associated OC with a lower surface loading. This implies that fine mineral-associated OC storage in the studied agricultural soils was driven by thicker accrual of OM and decoupled from clay content limitations.

有机碳 (OC) 与细矿物颗粒之间的相关性证实了土壤矿物质丰度与活性表面结合并增加有机质 (OM) 的持久性的重要作用。OM 的储存广泛地由颗粒和矿物相关形式组成。关于细矿物土壤颗粒对 OM 储存影响的相关研究大多结合了来自不同地点的数据，这些数据可能被其他环境因素混淆。在这里，我们分析了土壤粘土含量梯度为 5-37% 且具有相似农场管理和矿物质成分的 OM 储存。在整个粘土梯度中，土壤含有 14 mg OC g ^-1平均在大块土壤中没有显示任何系统性增加。密度分馏表明，在高粘土（18-37% 粘土）中，更大比例的 OC 以吸留颗粒 OM 的形式储存。在低黏土（5-18% 黏土）中，精细矿物相关部分的 OC 含量比高黏土高出两倍。比表面积测量表明，更多的矿物相关 OM 与更高的 OC 负载有关。这表明在相同矿物表面积的低黏土细粒中，可能存在更厚的 OM 累积。随着粘土含量的增加，OM 存储形式包含更多的颗粒 OC 和矿物相关的 OC，表面负载较低。