施用生物炭对土壤呼吸以及土壤有机碳组分的影响

为确定生物炭对土壤呼吸速率以及土壤碳组分的影响，采用田间小区试验，以苹果果树枝条生物炭为试验材料，研究了添加0、20、40、60、80 t/hm2的苹果果树枝条生物炭后，小麦生态系统呼吸（R_e）、土壤呼吸（R_s）、植物呼吸（R_p）、土壤TOC（总有机碳）、土壤POC（颗粒有机碳）、WSOC（土壤水溶性有机碳）和土壤AOC（易氧化有机碳）的变化以及各指标之间的相关性.结果表明，添加生物炭显著提高了小麦生态系统呼吸速率、土壤呼吸速率和植物呼吸速率，与对照相比分别增加了9.98%~27.57%、9.33%~19.47%和10.18%~30.14%，并且生物炭施用量为20和40 t/hm2时土壤呼吸速率显著高于其他两个处理，而对于小麦生态系统呼吸速率和植物呼吸速率来说，施用40 t/hm2生物炭时其值最高.对于土壤碳组分，施用生物炭显著提高了0~20 cm土层中土壤w（TOC）、w（POC）和w（AOC），并且土壤w（TOC）和w（POC）与生物炭施用量呈极显著正相关.对于WSOC而言，当生物炭施用量高于40 t/hm2时其值显著降低，与对照相比，0~10、>10~20和>20~30 cm三个土层中w（WSOC）分别降低了21.82%~28.37%、35.88%~36.58%和32.28%~44.07%.研究显示，适量施用生物炭能够提高土壤w（TOC）、w（POC）和w（AOC）而降低了w（WSOC），但同时也增加了小麦生态系统呼吸速率. 

Influence of Biochar on Soil Respiration and Soil Organic Carbon Fractions

Biochar addition to soil has been widely accepted as a soil conditioner to improve soil physical and biochemical properties, increase crop yields and enhance fertilizer use efficiency. However, there has always been a dispute about whether biochar inhibits soil respiration. Five levels of branches-derived biochar from apple tree (0, 20, 40, 60 and 80 t/hm2) were used. The effects of biochar on ecosystem respiration (R_e), soil respiration (R_s), plant respiration (R_p), total soil organic carbon (TOC), soil particulate organic carbon (POC), soil active organic carbon (AOC) and water-soluble organic carbon (WSOC) were investigated in a plot trial. The results showed that, compared to the control treatment, ecosystem respiration, soil respiration and plant respiration were increased by 9.98%-27.57%, 9.33%-19.47% and 10.18%-30.14%, respectively. Soil respiration was higher at biochar levels of 20 and 40 t/hm2 than that in the biochar levels of 60 and 80 t/hm2, while ecosystem respiration and plant respiration reached the maximum at 40 t/hm2. Biochar amendment significantly increased the contents of TOC, POC and AOC in the 0-20 cm soil layer, and the contents of TOC and POC were positively correlated with the biochar dosage. The contents of WSOC significantly decreased at biochar levels of 60 and 80 t/hm2, and it decreased respectively by 21.82%-28.37%, 35.88%-36.58% and 32.28%-44.07% in 0-10, >10-20 and >20-30 cm soil layers compared to the control. The results indicated that as a long-term mechanism of carbon sequestration, biochar improved the total soil organic carbon. In addition, soil respiration could be improved by biochar amendment.