硝态氮源及碳源有效性对土壤N_2O和CO_2排放的影响

以华北平原农田土壤为对象,通过室内静态培养系统研究NO_3~--N与不同碳源组合对土壤N_2O和CO_2排放的影响。结果表明,NO_3~--N作为氮源和不同碳源施入土壤,除NO_3~-+纤维素,其余土壤N_2O排放通量均高于对照组和只添加氮源土壤;NO_3~--N和不同碳源组合的CO_2累积排放量均高于对照和只添加氮源土壤。NO_3~-+果胶的N_2O排放量在第1 d达到最大值1 383.42μg N·kg~(-1)·d~(-1);NO_3~-+葡萄糖的CO_2排放量在第1 d达到最大值370.13 mg C·kg~(-1)·d~(-1),CO_2累积排放量顺序为:葡萄糖果胶秸秆纤维素淀粉木质素。土壤NO_3~--N含量与N_2O排放呈极显著正相关。总之,添加纤维素可以抑制N_2O的排放,促进CO_2排放,并增加土壤中NO_3~--N含量,添加其余碳源均会促进土壤N_2O和CO_2排放。

Effect of the Availability of Nitrate Nitrogen and Carbon Source on N2O and CO2 Emission from Soil

Effects of the availability of nitrate nitrogen and different carbon sources on N2O and CO2 emission from soil of typical farmland in the North China were studied. The static culture systems were adopted in an indoor experiment. The results illustrated that, compared with single nitrate nitrogen fertilizer, combined different carbon sources and nitrate nitrogen fertilizer increased the emission of N2O from soil, except for cellulose;combined different carbon sources and nitrate nitrogen fertilizer increased the accumulated emission of CO2 from soil. The emission flux of N2O by treatment of pectin peaked 1 383.42μg N·kg-1·d-1 on day 1.The emission flux of CO2 by treatment of glucose peaked 370.13 mg C·kg-1·d-1 on day 1, and the accumulated emission of CO2 order was:glucose>pectin>straw>cellulose>starch>lignin. It showed a highly signifcant positive correlation between the content of NO-3-N and emission of N2O. Overall, combined cellulose and nitrate nitrogen fertilizer suppressed the N2O emission, improved the CO2 emission, and increased NO-3-N content;combined other carbon sources and nitrate nitrogen fertilizer promoted the N2O and CO2 emission.