秸秆、氮肥和食细菌线虫交互作用对土壤活性碳氮和温室气体排放的影响

采用3因素2水平交互设计室内恒温培养试验，通过调控秸秆施用、氮肥用量及食细菌线虫，探讨三者对土壤微生物生物量碳氮(C_mic和N_mic)、可溶性碳氮(DOC、DON)、矿质氮(NH₄⁺-N和NO₃^--N)及温室气体排放(CO₂、N₂O和CH₄)的交互影响.结果表明： 施用秸秆显著增加了食细菌线虫数量、C_mic和N_mic，而随着氮肥用量增加，C_mic和N_mic降低，食细菌线虫对C_mic和N_mic的影响则依赖于秸秆和氮肥用量.秸秆、氮肥和食细菌线虫对可溶性碳氮和矿质氮表现出强烈的交互作用，其中秸秆和氮肥均增加了DOC、NH₄⁺ -N和NO₃^--N；食细菌线虫对DOC的抑制作用和对矿质氮的促进作用达到显著水平.秸秆处理对CO₂、N₂O的促进及对CH₄的抑制均达到显著水平，而线虫和氮肥的影响则更多表现出交互作用.在培养第56天，有秸秆时，低量氮肥下食细菌线虫显著促进了CO₂的排放，而高量氮肥下则表现出对CO₂和N₂O显著的抑制作用.总之，土壤生态功能的发挥不可忽视土壤动物的作用.

Interactions of straw,nitrogen fertilizer and bacterivorous nematodes on soil labile carbon and nitrogen and greenhouse gas emissions.

A 3×2 factorial design of microcosm experiment was conducted to investigate the interactive effects of straw, nitrogen fertilizer and bacterivorous nematodes on soil microbial biomass carbon (C_mic) and nitrogen (N_mic), dissolved organic carbon (DOC) and nitrogen (DON), mineral nitrogen (NH₄⁺ -N and NO₃^- -N), and greenhouse gas (CO₂, N₂O and CH₄) emissions. Results showed that straw amendment remarkably increased the numbers of bacterivorous nematodes and the contents of C_mic and N_mic, but C_mic and N_mic decreased with the increasing dose of nitrogen fertilization. The effects of bacterivorous nematodes strongly depended on either straw or nitrogen fertilization. The interactions of straw, nitrogen fertilization and bacterivorous nematodes on soil DOC, DON and mineral nitrogen were strong. Straw and nitrogen fertilization increased DOC and mineral nitrogen contents, but their influences on DON depended on the bacterivorous nematodes. The DOC and mineral nitrogen were negatively and positively influenced by the bacterivorous nematodes, respectively. Straw significantly promoted CO₂ and N₂O emissions but inhibited CH₄ emission, while interactions between nematodes and nitrogen fertilization on emissions of greenhouse gases were obvious. In the presence of straw, nematodes increased cumulative CO₂ emissions with low nitrogen fertilization, but decreased CO₂ and N₂O emissions with high nitrogen fertilization on the 56^th day after incubation. In summary, mechanical understanding the soil ecological process would inevitably needs to consider the roles of soil microfauna.