Erosion-induced Impact on Carbon Dynamics in the Crop-Rhizosphere Microbiome-Soil Organic Matter-Continuum (CropRhizoSOM)

土壤侵蚀对土壤碳储量变化的影响程度和机制至今尚未明确。农田可以被认为是改善碳固存的一种重要生态系统类型，因为它们覆盖了1400万平方公里的地球陆地表面，储存了全球土壤有机碳的十分之一，并且得到持续管理。了解侵蚀对土壤碳动态和碳储量的影响机制是量化侵蚀对农田碳源和碳汇功能的重要性的先决条件。我们的目标是为这一悬而未决的问题作出实质性贡献。拟议的项目将调查在表层土壤（Ap层）中混合不同量的底土对作物-土壤圈微生物-土壤有机质连续体（CropRectum SOM）中碳动力学关键过程的影响。该联合体将进行基于14 C示踪剂的春大麦盆栽试验，其中将比较分析来自实验地点CarboZALF-D的未侵蚀Ap材料（对照，无Bt掺入）、中度侵蚀Ap材料（含20% Bt材料）和强烈侵蚀Ap材料（含40% Bt材料）。CropRectum SOM将定量确定和平衡（I）碳通量和分配率，（II）土壤微生物群的功能适应（基因标记，宏基因组，土壤酶），和（III）在不同生长阶段和随后的休闲期，各种土壤颗粒大小组分中有机碳的动态。随后，我们将确定哪些碳库主要由作物和微生物群访问。在所有结果的基础上，将开发一个考虑微生物群通量率和功能变化的概念模型。这一概念模型的建立将为今后土壤碳模型的试验和改进奠定基础。

The magnitude and mechanistic impact of soil erosion on changes of soil carbon stocks are not resolved to date. Croplands can be considered as one important type of ecosystem to improve carbon sequestration, since they cover 14 million square kilometres of earth land surface, store one-tenth of the global soil organic carbon, and are continuously managed. An understanding of the mechanisms responsible for erosion impact on soil carbon dynamics and storage is a prerequisite for a quantification of the significance of erosion on the carbon source and sink functions of croplands. We aim for a substantial contribution to this unresolved topic. The proposed project will investigate the effect of mixing of different amounts of subsoil in a topsoil (Ap horizon) on key processes of carbon dynamics in a Crop-Rhizosphere Microbiota-Soil Organic Matter Continuum (CropRhizoSOM). The consortium will conduct 14C-tracer-based pot experiments with spring barley, in which a non-eroded Ap material from the experimental site CarboZALF-D (control, without Bt incorporation), a moderately eroded Ap material (with 20% Bt material) and strongly eroded Ap material (with 40% Bt material) will be comparatively analyzed. CropRhizoSOM will quantitatively determine and balance (I) carbon fluxes and allocation rates, (II) the functional adaption of the soil microbiota (gene markers, metagenomes, soil enzymes), and (III) the dynamics of organic carbon in various soil particle size fractions at different growth stages and in the following fallow period. Subsequently, we will identify which carbon pools were primarily accessed by the crop and the microbiota. On the basis of all results, a conceptual model considering flux rates and functional changes of the microbiota will be developed. Such a conceptual model will lay the foundations for subsequent experiments and adaptations in soil carbon models by future efforts.