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

到目前为止，土壤侵蚀对土壤碳储量变化的大小和机理的影响还没有得到解决。农田可以被认为是改善碳固定的一种重要的生态系统类型，因为它们覆盖了1400万 平方公里的地球陆地，储存了全球土壤有机碳的十分之一，并且是持续管理的。了解侵蚀对土壤碳动态和储存的影响机制，是量化侵蚀对农田碳源和碳汇功能重要性的前提。我们的目标是为这个悬而未决的话题做出实质性贡献。该项目将研究在表土(AP层)中混合不同数量的底土对作物-根际微生物-土壤有机质连续体(CropRhizoSOM)碳动态的关键过程的影响。该联盟将用春大麦进行基于14C示踪剂的盆栽试验，其中将对试验场CarboZALF-D(对照，未加入Bt)的非侵蚀AP材料、中度侵蚀的AP材料(含20%Bt材料)和强侵蚀AP材料(含40%Bt材料)进行对比分析。CropRhizoSOM将定量地确定和平衡(I)碳通量和分配速率，(Ii)土壤微生物区系(基因标记、后基因组、土壤酶)的功能适应，以及(Iii)不同生长阶段和随后休闲期不同粒度土壤中有机碳的动态变化。随后，我们将确定哪些碳库主要由作物和微生物区系获得。在所有结果的基础上，将建立一个考虑通量速率和微生物区系功能变化的概念模型。这一概念性模型将为后续的土壤碳模型实验和改进奠定基础。

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.