Contrasting short-term responses of soil heterotrophic and autotrophic respiration to biochar-based and chemical fertilizers in a subtropical Moso bamboo plantation

Application of biochar-based fertilizer (BF), produced by combining biochar with chemical fertilizer, is known to be an effective way to increase plant growth and soil organic carbon (SOC) stock, but its impact on soil respiration (R-S) components and associated mechanisms in subtropical plantations remain unclear. The objectives of this 12-month field study were (1) to examine the effects of the application of a BF versus a chemical fertilizer (CF) on seasonal variations in soil heterotrophic (R-H) and autotrophic (R-A) respiration in a subtropical plantation of Moso bamboo (Phyllostachys edulis), and (2) to investigate relationships between soil R-H and R-A and soil environmental factors in different fertilizer treatments. Four treatments were tested: control (no fertilizer applied), BF application, CF application, and a 50: 50 mixture of BF and CF (BCF). Irrespective of the treatment, both R s and R-H exhibited strong seasonal patterns. However, adding CF in the soil significantly increased the soil R-H whereas BF decreased it (P < 0.05). Both CF and BF significantly (P < 0.05) increased soil R-A. The R-S, R-H and R-A were all exponentially related (P < 0.05) to soil temperature regardless of the treatment, and the Q(10) value of R-H was greater than that of R-A (P < 0.05). Applying CF increased the Q(10 )for R-H (P < 0.05), yet the application of BF did not affect it. Although the R-S, R-H and R-A were not related to the soil moisture content in all treatments, both R-S and R-H were correlated (P < 0.05) with soil water soluble organic C and microbial biomass C concentrations, and also with soil invertase and beta-glucosidase activities. In conclusion, compared with the conventional chemical fertilizer use, the novel management practice of biochar-based fertilizer application offers advantages, such as reducing soil C emissions and increasing SOC content, which has the implication of mitigating soil greenhouse gas emissions in subtropical Moso bamboo plantations.

Automated summary

This study compares the effects of biochar-based fertilizer and chemical fertilizer on soil respiration in subtropical Moso bamboo plantations, finding that soil respiration shows obvious seasonal variations regardless of treatment. Chemical fertilizer significantly increases heterotrophic respiration, while biochar decreases it. Additionally, soil respiration is exponentially related to soil temperature, with chemical fertilizer having a greater impact on respiration.