The object of this study was to explore the effect of biochar on Loess Plateau calcareous arable soil organic carbon mineralization under the condition of with or without nitrogen-fertilizer addition. Maize straw–derived biochars were prepared at 400 and 800 °C (BC400 and BC800), respectively. After physicochemical property determination, biochars were thoroughly mixed with soil at the mass ratio of 1% and 2% respectively, and a control without biochar addition was also arranged. Each treatment was carried out with 6 replicates, half of which were subjected to nitrogen-fertilizer addition. After 1-week preincubation, 50-day indoor static soil incubation experiment was carried out consecutively. Results showed that compared with BC400, pH, carbon content, alkaline oxygen-containing functional group, and specific surface area of BC800 significantly increased, while dissolved organic carbon, nitrogen, hydrogen, oxygen contents, carboxyl, carbonyl, and acidic oxygen-containing functional group significantly decreased. In the treatments without nitrogen-fertilizer addition, maize straw–derived biochar inhibited CO2 emission, especially for BC800-1% and BC800-2%. However, in the treatments with nitrogen-fertilizer addition, the biochar promoted CO2 emission, especially for BC400-1% and BC400-2%. Moreover, the pyrolysis temperature of biochar preparation showed more crucial impact on CO2 emission than its application rate. CO2 emission was significantly correlated with total organic carbon/inorganic nitrogen (TOC/IN) and dissolved organic carbon/inorganic nitrogen (DOC/IN). However, DOC/IN explained the variance of CO2 emission with a higher degree than TOC/IN. Carbon/nitrogen mass ratio was the key factor in controlling CO2 emission from biochar-amended soil, and DOC/IN showed more significant effect on CO2 emission than TOC/IN.

中文翻译：

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施氮肥和不施氮肥条件下玉米秸秆生物质炭对钙质耕地有机碳矿化的影响

【摘要】：本研究的目的是探讨在增施或不施氮肥条件下生物炭对黄土高原钙质耕地土壤有机碳矿化的影响。玉米秸秆衍生的生物炭分别在 400 和 800 °C（BC400 和 BC800）下制备。理化性质测定后，将生物炭按质量比分别为1%和2%与土壤充分混合，并设置不添加生物炭的对照。每个处理进行 6 个重复，其中一半进行氮肥添加。预孵化1周后，连续进行50天的室内静态土壤孵化实验。结果表明，与BC400相比，pH、碳含量、碱性含氧官能团、BC800 的比表面积显着增加，而溶解有机碳、氮、氢、氧含量、羧基、羰基和酸性含氧官能团的含量显着降低。在不添加氮肥的处理中，玉米秸秆生物炭抑制了 CO2 排放，尤其是 BC800-1% 和 BC800-2%。然而，在施氮肥处理中，生物炭促进了CO2的排放，尤其是BC400-1%和BC400-2%。此外，生物炭制备的热解温度对 CO2 排放的影响比其施用率更重要。CO2 排放与总有机碳/无机氮 (TOC/IN) 和溶解有机碳/无机氮 (DOC/IN) 显着相关。然而，DOC/IN 比 TOC/IN 更能解释 CO2 排放的方差。碳/氮质量比是控制生物炭改良土壤CO2排放的关键因素，DOC/IN对CO2排放的影响比TOC/IN更显着。