Straw input contributes to the formation of soil organic carbon and multi-carbon pools

Distinguishing between plant-derived and microbial-derived organic carbon is key to determining the formation of soil organic carbon pools. In fertilized farmland ecosystems, the formation, turnover and accumulation of soil organic carbon are regulated by fertilizer types and soil microorganisms and their interactions. Different fertilizer inputs may change the utilization strategies of soil microorganisms, thereby affecting the retention of carbon from plant and microbial sources, and ultimately affecting the accumulation and stability of soil organic carbon.

Wang Kelin, a researcher at the Institute of Subtropical Agroecology of the Chinese Academy of Sciences, relied on the experimental platform of long-term dryland fertilization at the Huanjiang Karst Station of the Chinese Academy of Sciences (hereinafter referred to as the Huanjiang Station), and used amino sugars, lignophenols and globulomycin as molecular markers to study the high and low levels (30% and 60% The effects of six different fertilization treatments of straw and cow manure instead of chemical fertilizer on plant and microbial carbon in soil, combined with soil microbial life history strategies, explained the mechanism of different fertilization on organic carbon accumulation from different sources.

Real view of the sample plot of long-term fertilization community. Photo courtesy of the interviewee

The results showed that compared with chemical fertilizer alone, the combined application of high-level straw significantly increased the content of lignogenol and its contribution to soil organic carbon, and the combined application of high-level straw or cow manure significantly increased the content of microbial residue carbon and ballomycin. Therefore, the application of straw contributed to the lowest and highest bacterial and fungal K/r ratios in the fertilization treatment. The bacterial K/r ratio is an important factor in predicting the carbon content of bacterial residues, and there is a significant negative correlation between the two.

At the same time, straw input directly affected the accumulation of lignophenol and microbial residue carbon, while cow manure input indirectly affected the accumulation of microbial residue carbon by influencing microbial life history strategies. In conclusion, compared with chemical fertilizer alone, straw input contributed to the formation of soil organic carbon and multi-carbon pools. Soil microbial life history strategies are an important driving force for soil organic carbon formation and affect the accumulation and stability of soil organic carbon in agroecosystems.

Soil, biology and water sampling sites in the dryland auxiliary observation field of Huanjiang Station. Photo courtesy of the interviewee

The findings were recently published in Science of the Total Environment. The research was co-funded by the National Key R&D Program of China and the National Natural Science Foundation of China.