施用生物炭对土壤呼吸以及土壤有机碳组分的影响

Influence of Biochar on Soil Respiration and Soil Organic Carbon Fractions

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/hm^2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/hm^2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/hm^2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0~20cm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/hm^2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.

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.