生物质炭对旱作春玉米农田N2O排放的效应

通过田间试验,采用密闭式静态暗箱-气相色谱法研究不同生物质炭添加量(0、10、20、30t·hm-2)对黄土旱塬旱作春玉米农田N2O排放的影响。结果表明:生物质炭添加降低了施氮农田春玉米生长季N2O排放通量峰值和排放总量,添加30、20、10 t·hm-2生物质炭的三个处理N2O排放总量比不添加生物质炭的处理分别降低19.24%、9.89%、3.40%,其中添加30 t·hm-2生物质炭处理降低显著(P0.05),但添加20 t·hm-2的生物质炭未对不施氮农田N2O排放通量和总量产生显著影响。无论添加生物质炭与否,生长季不施氮处理的N2O排放通量和总量均显著低于施氮处理。添加生物质炭不同程度提升了农田0 cm和10 cm土壤温度,减少了施氮处理0~20cm土壤NH+4-N和NO-3-N含量,但对农田0~20 cm土层土壤含水量影响不显著。相关分析表明,试验农田N2O的排放通量与0~20 cm土层土壤NO-3-N和NH+4-N含量、含水量均呈极显著正相关关系(P0.001),与0 cm与10 cm土壤温度呈负相关关系。添加生物质炭后矿质氮含量的减少可能是旱作春玉米农田N2O排放减少的主要原因。

Effect of Biochar on Nitrous Oxide Emissions from Dryland Spring Corn Field on the Loess Plateau

A field experiment was conducted to measure N₂O emissions using static chamber-gas chromatography method. Six treatments were used:C0N0(no biochar, no N), C2N0(20 t·hm^-2 biochar, no N), C0N1(no biochar, 225 kg N·hm^-2), C1N1(10 t·hm^-2 biochar, 225 kg N·hm^-2), C2N1(20 t·hm^-2 biochar, 225 kg N· hm^-2) and C3N1(30 t·hm^-2 biochar, 225 kg N·hm^-2). Compared to C0N1 treatment, biochar amendments decreased cumulative N₂O emissions by 3.40%, 9.89% and 19.24% for the C1N1, C2N1 and C3N1, respectively. Additions of biochar increased soil temperature at 0 cm and 10 cm soil layers, but decreased mineral N content in 0~20 cm soil. Soil moisture in 0~20 cm was not affected by biochar. A significant positive correlation was found between N₂O emissions and soil NO₃^--N, NH₄⁺-N content and soil moisture in 0~20 cm soil, while a negative correction were observed between N₂O emissions and soil temperature at 0 cm and 10 cm. The reduction in mineral N concentrations by biochar was the main factor that reduced the N₂O emissions in dryland spring corn field.