等碳量添加不同有机物料对土壤有机碳组分及土壤呼吸的影响

为探明不同有机物料对土壤有机碳组分和呼吸速率的影响，研究了等碳量添加生物炭、秸秆、生物炭+秸秆条件下烤烟生长过程中土壤总有机碳（TOC）、易氧化有机碳（ROC）、可溶性有机碳（DOC）、微生物量碳（MBC）含量及土壤呼吸速率的动态变化，分析了土壤各有机碳组分之间及其与土壤呼吸速率的关系。研究结果显示，与单施化肥相比，等碳量添加有机物料后土壤各有机碳组分含量以及土壤呼吸速率均显著提高；添加有机物料的3个处理中，单施生物炭处理土壤TOC含量最高，CO₂排放量最低；单施秸秆处理土壤活性有机碳（AOC）占TOC的比例及CO₂排放量最高，但TOC含量最低；生物炭+秸秆处理土壤TOC含量显著高于添加秸秆处理，AOC含量显著高于单施生物炭处理，且CO₂排放量显著低于单施秸秆处理。土壤ROC、DOC、MBC之间关系密切，三者与土壤呼吸速率均呈显著正相关。由此可见，等碳量添加有机物料条件下，生物炭有利于土壤有机碳的固存，可减少CO₂的排放，但短期内对提高土壤AOC的效果不如秸秆直接还田明显，而秸秆直接还田对土壤AOC含量的提升效果最好，但会增加CO₂的排放，两者配施既提高了土壤AOC的含量，又减少了CO₂的排放。 

Effects of organic material application on organic carbon in and respiration of soil

In order to explore the effects of different organic materials on soil organic carbon fraction and respiration rate, contents of total organic carbon (TOC), readily oxidized organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) as well as soil respiration rate were investigated using flue cured tobacco growing in soils adding biochar, straw, and biochar and straw in combination. The correlation among soil organic carbon components as well as the correlation between soil respiration rate and soil organic carbon fractions were analyzed. Results showed that soil organic carbon content and soil respiration rate increased significantly after adding organic materials. TOC content was the highest and CO₂ emission was the lowest in biochar application treatment. In straw application treatment, the active organic carbon (AOC) content and CO₂ emissions were the highest, while TOC content was the lowest. Under combined application of biochar and straw, TOC content was significantly higher than that under single application of straw. AOC content was significantly higher than that under single application of biochar, and the emission of CO₂ was significantly lower than that under single application of straw. The contents of ROC, DOC and MBC were closely related with each other, and were all positively correlated with soil respiration rate. Under the condition of adding organic materials, biochar is beneficial to the retention of soil organic carbon and reduction of CO 2 emission. However in a short term, the effect of biochar application improving soil AOC is not as significant as that of straw application. In contrast, straw application can increase AOC content and the emission of CO₂. Therefore, the combined application of biochar and straw can improve AOC content while reducing CO₂ emission.