Molecular and Microscopic Insights into the Formation of Soil Organic Matter in a Red Pine Rhizosphere

Soil Systems

Dohnalkova, Alice C.¹ 

关键词: rhizosphere;    soil organic matter;    soil microbiome;    16S sequencing;    mineral weathering;    Fourier-transform ion cyclotron resonance mass spectrometry;    electron microscopy;    mineral-organic associations;    carbon cycle;   

DOI  :  10.3390/soils1010004

学科分类：土壤学

来源: mdpi

【 摘 要 】

Microbially-derived carbon inputs to soils play an important role in forming soil organic matter (SOM), but detailed knowledge of basic mechanisms of carbon (C) cycling, such as stabilization of organic C compounds originating from rhizodeposition, is scarce. This study aimed to investigate the stability of rhizosphere-produced carbon components in a model laboratory mesocosm of Pinus resinosa grown in a designed mineral soil mix with limited nutrients. We utilized a suite of advanced imaging and molecular techniques to obtain a molecular-level identification of newly-formed SOM compounds, and considered implications regarding their degree of long-term persistence. The microbes in this controlled, nutrient-limited system, without pre-existing organic matter, produced extracellular polymeric substances that formed associations with nutrient-bearing minerals and contributed to the microbial mineral weathering process. Electron microscopy revealed unique ultrastructural residual signatures of biogenic C compounds, and the increased presence of an amorphous organic phase associated with the mineral phase was evidenced by X-ray diffraction. These findings provide insight into the formation of SOM products in ecosystems, and show that the plant- and microbially-derived material associated with mineral matrices may be important components in current soil carbon models.

【 授权许可】

CC BY