Applied Mathematics (Modelling and Numerics), Department of Mathematics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
Soil Science, Research Department Life Science Systems, TUM School of Life Sciences, Technical University of Munich, Freising-Weihenstephan, Germany.
Glob Chang Biol. 2022 Aug;28(15):4589-4604. doi: 10.1111/gcb.16230. Epub 2022 May 27.
The structure of soil aggregates plays an important role for the turnover of particulate organic matter (POM) and vice versa. Analytical approaches usually do not disentangle the continuous re-organization of soil aggregates, caught between disintegration and assemblage. This led to a lack of understanding of the mechanistic relationship between aggregation and organic matter dynamics in soils. In this study, we took advantage of a process-based mechanistic model that describes the interaction between the dynamic (re-)arrangement of soil aggregates, based on dynamic image analysis data of wet-sieved aggregates, to analyze the turnover of POM, and simultaneous soil surface interactions in a spatially and temporally explicit way. Our novel modeling approach enabled us to unravel the temporal development of aggregate sizes, organic carbon (OC) turnover of POM, and surface coverage as affected by soil texture, POM input, and POM decomposition rate comparing a low and high clay soil (18% and 33% clay content). Our results reveal the importance of the dynamic re-arrangement of soil structure on POM-related turnover of OC in soils. Firstly, aggregation was largely determined by the POM input fostering aggregates through additional gluing joints outweighing soil texture at lower decomposition rate, whereas at higher decomposition rate, soil texture had a higher influence leading to larger aggregates in the high clay soil. Secondly, the POM storage increased with clay content, showing that surface interactions may delay the turnover of OC into CO . Thirdly, we observed a structural priming effect in which the increased input of POM induced increased structural re-arrangement stimulating the mineralization of old POM. This work highlights that the dynamic re-arrangement of soil aggregates has important implications for OC turnover and is driven by underlying surface interactions where temporary gluing spots stabilize larger aggregates.
土壤团聚体结构对颗粒有机物质（POM）的周转起着重要作用，反之亦然。分析方法通常无法区分土壤团聚体的连续再组织化过程，因为团聚体处于解体和聚集的动态变化中。这导致人们对土壤团聚体与有机物质动态之间的机械关系缺乏理解。在这项研究中，我们利用了一个基于过程的机械模型，该模型描述了土壤团聚体的动态（重新）排列的相互作用，其基础是湿筛团聚体的动态图像分析数据，以便以时空显式的方式分析 POM 的周转和同时发生的土壤表面相互作用。我们的新模型方法使我们能够揭示团聚体大小、受土壤质地、POM 输入和 POM 分解率影响的 POM 相关有机碳（OC）周转以及表面覆盖率的时间发展。我们的结果揭示了土壤结构的动态重排对土壤中 POM 相关 OC 周转的重要性。首先，团聚体主要由 POM 输入决定，通过增加胶结连接促进团聚体的形成，而在较低的分解率下，胶结连接的作用超过了土壤质地，而在较高的分解率下，土壤质地的影响更大，导致高粘土土壤中的团聚体更大。其次，POM 储存量随粘粒含量的增加而增加，这表明表面相互作用可能会延迟 OC 向 CO 的转化。第三，我们观察到结构引发效应，即 POM 输入的增加诱导了结构的重新排列，从而刺激了旧 POM 的矿化。这项工作强调了土壤团聚体的动态重排对 OC 周转具有重要意义，并且是由潜在的表面相互作用驱动的，其中临时胶结点稳定较大的团聚体。
