Soil aggregates are particles or small clumps formed naturally by soil particles. The stability of soil aggregates is an important indicator for predicting soil water loss and soil erosion. Soil aggregates are affected by many factors, such as the growth of plant roots, the physical and chemical properties of soil, the activities of soil animals and microorganisms, and artificial management. Plant roots effectively control soil erosion and stabilize soil structure, which has a crucial influence on the formation of aggregates and soil organic carbon (SOC) sequestration.  

Under the guidance of Prof. LIU Yi, LI Junya, a graduate student of Wuhan Botanical Garden, conducted sampling and analysis of the rhizosphere and non-rhizosphere soil of fibrous root plants and tap root plants in the National Nature Reserve of Danjiang Wetland in Henan province, and studied the SOC content of stability distribution and the dynamic directions of ¹³C in aggregates with different particle sizes.  

Rhizosphere effects significantly improved the stability of soil aggregates and promoted the carbon sequestration of soil aggregates. The general flow direction of SOC was from rhizosphere to non-rhizosphere, and from large aggregates to small aggregates in the root zone environment. The size of the flow, showing that movement between rhizosphere soil aggregates associated with fibrous root plants, was clearly higher than that of non-rhizosphere soil. The rhizosphere effect of fibrous root plants was significantly stronger than that of taproot plants. 

Results reveal that plant roots have the potential to regulate soil structural stability, and enhance soil erosion resistance and SOC sequestration. It is based on the cooperation between Wuhan Botanical Garden, CAS and the Nature Conservancy (TNC).  

The results of the study, published in the academic journal Agriculture, Ecosystems and Environment, are titled "Rhizosphere Effects Promote Soil Aggregate Stability and Associated organic Carbon Sequestration in Rocky Areas of Desertification”. It is supported by the National Natural Science Foundation of China and the Danjiang Project of the Nature Conservancy. 

Schematic diagram of C flow in the systems of rhizosphere and non-rhizosphere aggregates associated with different root type plants (Image by WBG)