Effect of Trichoderma on the Mineralization of Organic Carbon in Soil Aggregates

Propose  To investigate the effect of Trichoderma on the mineralization of soil aggregate organic carbon, providing scientific evidence for carbon transformation in different particle sizes of aggregates.

Methods An indoor constant temperature incubation experiment with or without Trichoderma treatment was conducted. Changes of the mineralization process of organic carbon and microbial community structure in bulk soil (BS), large macro-aggregates (LM), macro-aggregates (MA), and micro-aggregates (MI) were determined.

Results The application of Trichoderma had a significant impact on the mineralization of organic carbon and microbial abundance in different particle sizes of aggregates. After Trichoderma addition, organic carbon in MA showed a positive priming effect, with an accumulated mineralizable organic carbon of 1587.67 mg/kg; while a negative priming effect was observed in MI, and Trichoderma promoted the turnover of organic carbon in MI, with an accumulated mineralizable organic carbon of 1778.33 mg/kg. The addition of Trichoderma could increase the relative abundance of Proteobacteria, which reduced the positive priming effect of organic carbon to some extent. The application of Trichoderma mainly changed the relative abundance of soil Ascomycota and Basidiomycota, thereby affecting the stability of organic carbon.

Conclusion Trichoderma can enhance carbon retention in micro-aggregates and affect the relative abundance of Proteobacteria, Ascomycota and Basidiomycota in the soil.