生物质炭对旱作春玉米农田N_2O排放的效应

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

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、30 t·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豫、9.89豫、3.40豫，其中添加30 t·hm-2生物质炭处理降低显著（P〈0.05），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0～20 cm 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（P〈0.001），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。

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. Ad-ditions 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 NO -3 -N, NH ＋4 -N con-tent 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.