加气条件下土壤N2O排放对硝化/反硝化细菌数量的响应

摘要

为揭示加气灌溉及不同灌水量处理设施番茄地土壤N2O排放对土壤微生物的响应,于2016年8-12月在日光温室内进行试验,以充分供水的灌水量(W)为基准,设置0.6W、0.8W和1.0W3个灌水定额,每个灌水定额又设置加气和不加气处理,共计6个处理:0.6W加气(AI0.6)、0.6W不加气(CK0.6)、0.8W加气(AI0.8)、0.8W不加气(CK0.8)、1.0W加气(AI1.0)和1.0W不加气(CK1.0).结果表明,番茄生育前期,不同灌溉处理的土壤N2O排放通量呈下降的趋势;移植25 d后,N2O气体维持在较低且稳定的排放水平.与不加气处理相比,不同灌水定额的加气处理增加了土壤N2O排放,平均增加了4.7％;且随着灌水量的增加,土壤N2O排放也在增加,平均增加了1.9％,但处理间差异性均不显著(P＞0.05).就番茄全生育期微生物数量均值而言,加气较不加气处理增加了土壤硝化细菌数量,平均增加了2.1％;但加气减小了土壤反硝化细菌数量,平均降低了9.7％(P＞0.05).而随着灌水量的增加,土壤硝化细菌和反硝化细菌数量均逐渐增加(P＞0.05).相关分析表明,土壤N2O排放与土壤水分和土壤温度呈极显著正相关关系(P＜0.01),与土壤反硝化细菌数量呈极显著负相关关系(P＜0.01).试验结果为研究设施菜地土壤硝化和反硝化反应过程及氮循环奠定了理论基础.%Air injection and irrigation affect soil aeration,oxygen partial pressure and nitrogen turnover,which are bound to affect the processes of nitrification and denitrification,and influence production and emission of N2O.In order to study the response of soil N2O fluxes to nitrifying and denitrifying bacteria under aerated irrigation,the experiment was conducted in greenhouse tomato fields from August to December,2016.Based on the irrigation amount of adequate water supply (W),0.6W,0.8W and 1.0W were set as three different irrigation regimes.Each irrigation regime contained aeration and non-aeration.Hence,six treatments were set.The results showed that a downward trend of soil N2O fluxes was observed during the earlier stage of tomato,while soil N2O fluxes held at a relatively stable and low level since 25 d after transplanting.Compared with non-aerated irrigation,aerated irrigation increased soil N2O emissions by 4.7％ on average.Soil N2O emissions were increased with the increase of irrigation volume,which were increased by 1.9％ on average.But the treatment effects between aeration and irrigation regimes on soil N2O emissions were not significant (P ＞ 0.05).In terms of the mean values of microbial population throughout the whole tomato growth period,nitrifying bacteria under aerated irrigation was increased by 2.1％ on average compared with non-aerated irrigation,and denitrifying bacteria was decreased by 9.7％ on average (P ＞ O.05).In addition,nitrifying and denitrifying bacteria were increased with the increase of irrigation amount (P ＞ 0.05).Correlation analysis showed that the dependence of soil N2O flux on WFPS and soil temperature showed a significantly positive correlation under all treatments (P ＜0.01).The soil N2O flux was significantly and negatively correlated with denitrifying bacteria under different irrigation modes (P ＜ 0.01).The research results provided theoretical foundation for the process of nitrification and denitrification,and for the nitrogen cycle in the protected vegetable fields.