Recently, The team for "Soil Degradation Prevention and Soil Quality Improvement"  at the Institute of Agricultural Resources and Regional Planning of the Chinese Academy of Agricultural Sciences revealed the mutual feedback interaction between soil particle organic matter and soil pore structure. The research findings were published in the "Soil & Tillage Research" journal.

Soil particle organic matter is a mixture composed of undecomposed or partially decomposed plant residues and some microbial decomposition products. It has characteristics such as low density, large particles, high carbon-to-nitrogen ratio, rapid turnover, and easy decomposition by microorganisms, making it the most active component of soil organic matter. Soil pore structure directly determines water movement and gas exchange and plays an important role in the accumulation or transformation of particle organic matter (POM). However, the feedback interaction between soil particle organic matter and pore structure is not yet clear.

The research team found that ¹³C-labeled maize straw (fresh POM) exhibited similar feedback interactions in soil columns of Shajiang black soil and fluvo-aquic soil with different pore size distributions (Fig 1). On one hand, the decomposition of POM promoted the formation of new soil pores. There was good consistency between the volume loss from POM decomposition and the volume increase from pore formation. It promoted an increase in pore size of 100-300 μm in soils with lower bulk density and an increase in pore size of 50-100 μm in soils with higher bulk density (Fig 2). On the other hand, the study also revealed that pore size and average pore distance are important parameters in regulating particle organic matter decomposition. Pores of 100-300 μm significantly promoted the decomposition of particle organic matter (Fig 3), possibly due to the rapid diffusion of oxygen and carbon dioxide gases in such pores. The research results provide a scientific basis for further understanding the regulation pathways of soil organic matter decomposition.

Professor Peng Xinhua from the IARRP and Assistant Professor Guo Zichun from the Nanjing Institute of Soil Science, Chinese Academy of Sciences, are the co-corresponding authors of the paper, with PhD student Ding Tianyu as the first author. The research was supported by the National Key Laboratory for Efficient Utilization of Dryland and Semi-Arid Farmland in Northern China, the National Natural Science Foundation of China, and the Leading Talent Program of the Chinese Academy of Agricultural Sciences.

Article link: https://doi.org/10.1016/j.still.2024.106288