设施菜田与棚外粮田土壤菌群和反硝化气体产生的比较分析

Comparison of microbial communities and denitrifying gases emissions between the soils from a greenhouse and nearby farmland

【目的】对比设施菜田与棚外粮田土壤菌群以及N2O产生模式的差异。【方法】采用变性梯度凝胶电泳(DGGE)和反硝化功能基因(nir S,nos Z)方法分别比较两种土壤细菌群落以及功能基因类群丰度的差异,利用自动连续在线培养监测体系(Robot系统)测定两种土壤在好氧、厌氧阶段N2O等反硝化相关气态产物产生模式,分析N2O/(N2+N2O+NO)产物比。【结果】设施菜田与棚外粮田具有不同的土壤细菌群落结构,并且土壤细菌总量得到了显著的提升,然而两种反硝化功能基因(nir S,nos Z)丰度并没有显著变化。与设施菜田相比,棚外粮田有相对低的N2O积累量以及产物比,并且在厌氧初期气体产生模式有所不同。培养后铵态氮和亚硝态氮含量上升。【结论】设施菜田长期有别于棚外粮田的管理方式造成了土壤细菌群落的显著改变,增大了活跃微生物总量,造成土壤酸化,并导致N2O在气态产物中的比例升高。设施菜田土壤微生物进行了与棚外粮田不同的硝酸盐呼吸过程,异化硝酸盐还原成铵(DNRA)过程有可能贡献了两种土壤的部分厌氧N2O产生量。

[Objective] The soil microbial communities and N2 O emissions were compared between soil samples from a vegetable greenhouse and outside farmland. [Methods] Denaturing gradient gel electrophoresis（DGGE） and quantitative PCR were used to investigate the difference of soil microbialcommunities and functional gene abundance, respectively. A robotized incubation system was employed to analyze the gaseous products of denitrification and calculate the ratio of N2O/（N2＋N2O＋NO）. [Results] Significant differences were observed in soil bacterial communities between the two soils. The total number of bacteria in the greenhouse soil was higher than that of farmland. However, relative abundance of functional genes（nir S and nos Z） of the two types of soil was no significant difference. There were lower N2 O accumulation and N2O/（N2＋N2O＋NO） ratio in the farmland soil compared to the greenhouse soil. In addition, the patterns of gas emissions in the two soils were significantly different in the early stage of anaerobic incubation. DNRA might lead to the increase of ammonium nitrogen content after the anaerobic incubation. [Conclusion] The higher strength of fertilization in greenhouse soil resulted in significant changes in soil bacterial communities and higher active soil microbial mass, N2 O accumulation and N2O/（N2＋N2O＋NO） ratio. The soils from a greenhouse and a farmland, of which the greenhouse soil came from, have distinct nitrate respiration property. DNRA may be responsible for certain amounts of N2 O emissions in both soils.