Mineralization of soil organic carbon and CO₂ emission from the soil is slowed by interactions between organic matter and minerals. The main minerals involved are clay minerals and oxides but there is limited understanding of their effects when combined, as occurs in soil. We aimed to determine the effects of clay content and composition on organic carbon stabilization in soil, and the mechanisms involved. This was achieved by studying the decomposition of alfalfa residues in artificial soils made from quartz sand and kaolinite with and without additions of the non-layered colloids (NLCs) goethite, manganese oxide or imogolite. The artificial soils were inoculated with microbes from natural soil and incubated at 23 °C in the dark at 60% of water holding capacity for 180 days. With increasing contents of clay and NLCs, organic carbon mineralization decreased, whereas carbohydrate and microbial biomass carbon contents increased. Of the NLCs, goethite had the least effect and imogolite the greatest effect on carbohydrate content. The effects of the treatments on mineralization and carbohydrate content were explained mostly by specific surface area (>83% of variation), presumably due to the effects on sorption. The effects of the treatments on microbial biomass were related to the volume of habitat (water-filled pore space) and availability of substrate (influenced by sorption). These results showed that clay content and composition influenced the stabilization of soil organic carbon mostly through the supply of surfaces for sorption reactions rather than via interactions unique to particular colloids.

土壤有机碳和CO _2的矿化作用有机物和矿物质之间的相互作用减缓了土壤的排放。涉及的主要矿物质是粘土矿物质和氧化物，但结合在一起时（如在土壤中）对它们的作用了解甚少。我们旨在确定粘土含量和组成对土壤中有机碳稳定的影响，以及所涉及的机制。这是通过研究在石英砂和高岭石制成的人造土壤中添加或不添加非层状胶体（NLCs）针铁矿，氧化锰或水铁矿的过程中苜蓿残留物的分解而实现的。用天然土壤中的微生物接种人工土壤，并在黑暗中于23°C和60％持水量下孵育180天。随着粘土和NLC​​含量的增加，有机碳矿化减少，而碳水化合物和微生物生物量碳含量增加。在NLC中，针铁矿对碳水化合物含量的影响最小，而伊莫石对碳水化合物含量的影响最大。处理对矿化和碳水化合物含量的影响主要是由比表面积（> 83％的变化）解释的，大概是由于对吸附的影响。处理对微生物生物量的影响与栖息地的体积（充满水的孔隙空间）和底物的利用率（受吸附影响）有关。这些结果表明，粘土的含量和组成主要通过吸附反应的表面供应而不是通过特定胶体独特的相互作用来影响土壤有机碳的稳定性。针铁矿对碳水化合物含量的影响最小，而伊莫石对碳水化合物含量的影响最大。处理对矿化和碳水化合物含量的影响主要是由比表面积（> 83％的变化）解释的，大概是由于对吸附的影响。处理对微生物生物量的影响与栖息地的体积（充满水的孔隙空间）和底物的利用率（受吸附影响）有关。这些结果表明，粘土的含量和组成主要通过吸附反应的表面供应而不是通过特定胶体独特的相互作用来影响土壤有机碳的稳定性。针铁矿对碳水化合物含量的影响最小，而伊莫石对碳水化合物含量的影响最大。处理对矿化和碳水化合物含量的影响主要是由比表面积（> 83％的变化）解释的，大概是由于对吸附的影响。处理对微生物生物量的影响与栖息地的体积（充满水的孔隙空间）和底物的利用率（受吸附影响）有关。这些结果表明，粘土的含量和组成主要通过吸附反应的表面供应而不是通过特定胶体独特的相互作用来影响土壤有机碳的稳定性。大概是由于对吸附的影响。处理对微生物生物量的影响与栖息地的体积（充满水的孔隙空间）和底物的利用率（受吸附影响）有关。这些结果表明，粘土的含量和组成主要通过吸附反应的表面供应而不是通过特定胶体独特的相互作用来影响土壤有机碳的稳定性。大概是由于对吸附的影响。处理对微生物生物量的影响与栖息地的体积（充满水的孔隙空间）和底物的利用率（受吸附影响）有关。这些结果表明，粘土的含量和组成主要通过吸附反应的表面供应而不是通过特定胶体独特的相互作用来影响土壤有机碳的稳定性。