玉米秸秆及其黑炭添加对黄绵土CO_2和N_2O排放的影响

Coupling Effects of Water, Carbon and Nitrogen on Greenhouse Gas Emissions from Loessial Soil

采用二次通用旋转组合设计,在室内进行恒温(28℃)培养试验,探讨在室内培养条件下土壤水分、有机碳(秸秆、黑炭)和氮素耦合对温室气体(CO2和N2O)排放的影响,并建立回归模型对试验数据进行回归分析,结果表明:(1)相比施加秸秆来说,在土壤中施加黑炭具有显著的减排效果。(2)以秸秆作为碳源时,水、碳、氮三因子对土壤两种温室气体(CO2和N2O)累积排放量的影响大小均表现为有机碳>水分>氮素;以黑炭作为碳源时,水碳氮三因子对土壤CO2累积排放量的影响大小表现为水分>有机碳>氮素,对土壤N2O累积排放量的影响为有机碳>氮素>水分。(3)水碳氮交互作用对土壤CO2累积排放量的影响表现为:施加秸秆时为碳氮>水氮>水碳,施加黑炭时为水碳=水氮>碳氮;而对N2O累积排放量的影响而言,施加秸秆时为水碳>碳氮>水氮,施加黑炭时为水氮>碳氮>水碳。(4)研究认为,令CO2累积排放量最小的水碳氮组合以秸秆作为碳源时为水分含量30%、不施加秸秆和氮素施加量81.9 mg kg-1,以黑炭作为碳源时为水分含量10%、不施加黑炭和氮素施加量48.4 mg·kg-1;令N2O累积排放量最小的水碳氮组合以秸秆作为碳源时为水分含量30%、不施加秸秆和氮素施加量100 mg·kg-1,以黑炭作为碳源时为水分含量10%、不施加黑炭和氮素施加量100mg·kg-1。

Research has shown that direct returning of crop residues to fields may cause increases in greenhouse gas emissions from soils.This study investigated the coupling impacts of soil water content, organic carbon（maize stalk and its biochar）and nitrogen on the emissions of greenhouse gases（CO2and N2O）, using quadratic rotational combination design and laboratory incubation experiment（28 ℃）. When maize stalks were directly applied to the soil, CO2 and N2O emissions were mainly affected by organic carbon, followed by water and nitrogen; whereas CO2 emission was predominantly influenced by water, followed by organic carbon and nitrogen, but N2O emission was primarily controlled by organic carbon, followed by nitrogen and water, when biochar was added to soil. Effect of pairwise interactions on CO2 emission was in order of carbon-nitrogen〉water-nitrogen〉water-organic carbon when stalk was applied. When biochar was applied, however, the interactive effect on CO2 emission was water-nitrogen=water-carbon〉carbon-nitrogen. The interaction on N2O emission was water-carbon〉 carbon-nitrogen〉water-nitrogen when stalk was applied, but water-nitrogen〉carbon-nitrogen〉water-carbon when biochar was applied. For the lowest cumulative CO2 emission, the optimal combination would be a combination of 30% water content and 81.9 mg·kg^-1nitrogen without stalk addition, or 10% water content, no biochar applied and 48.4 mg·kg^-1 nitrogen. As for N2O emissions, a combination of 30% water content, no stalk amendment and 100 mg·kg^-1 nitrogen was the better condition when the maize stalk was amended. In contrast, when biochar used, the best condition was a combination of 10% water content, no biochar added and 100 mg·kg^-1 nitrogen. In summary, compared to stalk, the biochar can effectively reduce soil emissions of greenhouse gases.