Soil Science, TUM School of Life Sciences, Technical University of Munich, Freising-Weihenstephan, Germany.
Institute for Organic Farming, Soil and Resource Management, Bavarian State Research Center for Agriculture, Freising-Weihenstephan, Germany.
Nat Commun. 2021 Jul 5;12(1):4115. doi: 10.1038/s41467-021-24192-8.
The largest terrestrial organic carbon pool, carbon in soils, is regulated by an intricate connection between plant carbon inputs, microbial activity, and the soil matrix. This is manifested by how microorganisms, the key players in transforming plant-derived carbon into soil organic carbon, are controlled by the physical arrangement of organic and inorganic soil particles. Here we conduct an incubation of isotopically labelled litter to study effects of soil structure on the fate of litter-derived organic matter. While microbial activity and fungal growth is enhanced in the coarser-textured soil, we show that occlusion of organic matter into aggregates and formation of organo-mineral associations occur concurrently on fresh litter surfaces regardless of soil structure. These two mechanisms-the two most prominent processes contributing to the persistence of organic matter-occur directly at plant-soil interfaces, where surfaces of litter constitute a nucleus in the build-up of soil carbon persistence. We extend the notion of plant litter, i.e., particulate organic matter, from solely an easily available and labile carbon substrate, to a functional component at which persistence of soil carbon is directly determined.
最大的陆地有机碳库——土壤中的碳，是由植物碳输入、微生物活性和土壤基质之间复杂的联系所调控的。这表现为微生物——将植物衍生碳转化为土壤有机碳的关键参与者——是如何受到有机和无机土壤颗粒的物理排列的控制的。在这里，我们进行了一种用稳定同位素标记的凋落物的培养实验，以研究土壤结构对凋落物衍生有机物质命运的影响。虽然在质地较粗的土壤中微生物活性和真菌生长得到了增强，但我们表明，无论土壤结构如何，有机物质的封闭和有机-矿物结合的形成都会同时发生在新鲜凋落物表面。这两个机制——对有机物质持久性贡献最大的两个过程——直接发生在植物-土壤界面，在那里凋落物表面构成了土壤碳持久性形成的核心。我们将植物凋落物的概念，即颗粒有机物质，从仅仅是一种容易获得和不稳定的碳底物，扩展到一个功能组成部分，在这个组成部分中，土壤碳的持久性直接被决定。
