As the carbon (C) credit market evolves, incorporating organic matter into soils has emerged as a key strategy in C farming. Soil heterotrophic respiration (R_H) plays a pivotal role in maintaining the C balance in terrestrial ecosystems, yet the contrasting impacts of fresh and pyrogenic organic matter applications on soil R_H, and associated underlying mechanisms, have not been fully investigated. Through a 2-year field experiment, we investigated how applying maize straw and its derived biochar affect the physical, chemical, and microbial properties of soil in a subtropical Moso bamboo forest. Results showed that straw application increased soil R_H, while biochar application suppressed it. Soil R_H was correlated positively with β-glucosidase and cellobiohydrolase activities but negatively with RubisCO enzyme activity. Increased soil R_H under straw application was linked to the increased β-glucosidase/cellobiohydrolase activities driven by elevated water-soluble organic C and O-alkyl C levels as well as GH48 and cbhI gene abundances, and the decreased RubisCO enzyme activity caused by reduced cbbL gene abundance. Conversely, reduced soil R_H under biochar application was linked to reductions in β-glucosidase and cellobiohydrolase activities induced by increased aromatic C and decreased GH48 and cbhI gene levels, and increases in RubisCO enzyme activity driven by higher cbbL gene abundance. More importantly, changes in soil R_H were clearly linked to microbial dynamics. Specifically, increases in the relative abundances of Alphaproteobacteria and Sordariomycetes and decreases in AD3 and Tremellomycetes contributed to the enhanced soil R_H under straw application. With biochar application, the reverse effect occurred, ultimately contributing to the reduced soil R_H. Our study demonstrates that maize straw application increases while biochar application decreases soil R_H in the subtropical forest. These findings reveal that biochar reduced soil R_H through changing microbial activity in subtropical forests, providing insight into complex dynamics of soil C cycling in response to diverse interventions.

随着碳 (C) 信用市场的发展，将有机物纳入土壤已成为碳农业的一项关键策略。土壤异养呼吸（R _H）在维持陆地生态系统碳平衡方面发挥着关键作用，但新鲜和热解有机物应用对土壤 R _H的对比影响以及相关的潜在机制尚未得到充分研究。通过为期两年的田间试验，我们研究了施用玉米秸秆及其衍生的生物炭如何影响亚热带毛竹林土壤的物理、化学和微生物特性。结果表明，施用秸秆增加了土壤相对_湿度，而施用生物炭则抑制了土壤相对湿度。土壤相对湿度_与β-葡萄糖苷酶和纤维二糖水解酶活性呈正相关，与RubisCO酶活性呈负相关。秸秆施用下土壤相对湿度的增加_与水溶性有机 C 和 O-烷基 C 水平以及GH48和cbh I 基因丰度升高所驱动的 β-葡萄糖苷酶/纤维二糖水解酶活性增加有关，以及由cbbL基因丰度降低。相反，施用生物炭后土壤相对湿度的降低_{与芳香族 C 增加和}GH48和cbh I 基因水平降低引起的 β-葡萄糖苷酶和纤维二糖水解酶活性降低有关，以及cbbL基因丰度较高导致的 RubisCO 酶活性增加有关。更重要的是，土壤相对_湿度的变化与微生物动态明显相关。具体而言，秸秆施用下Alphaproteobacteria和Sordariomycetes相对丰度的增加以及AD3和Tremellomycetes的减少有助于提高土壤相对湿度_。应用生物炭会产生相反的效果，最终导致土壤相对湿度_降低。我们的研究表明，在亚热带森林中，玉米秸秆的施用增加，而生物炭的施用降低了土壤相对_湿度。这些发现表明，生物炭通过改变亚热带森林中的微生物活动来降低土壤相对湿度_，从而深入了解土壤碳循环响应不同干预措施的复杂动态。