Abstract:
The nitrification inhibitors (NIs) 3,4-dimethylpyrazole (DMPP) and dicyandiamide (DCD) can effectively reduce N2 O emissions; however, which species are targeted and the effect of these NIs on the microbial nitrifier community is still unclear. Here, we identified the ammonia oxidizing bacteria (AOB) species linked to N2 O emissions and evaluated the effects of urea and urea with DCD and DMPP on the nitrifying community in a 258 day field experiment under sugarcane. Using an amoA AOB amplicon sequencing approach and mining a previous dataset of 16S rRNA sequences, we characterized the most likely N2 O-producing AOB as a Nitrosospira spp. and identified Nitrosospira (AOB), Nitrososphaera (archaeal ammonia oxidizer) and Nitrospira (nitrite-oxidizer) as the most abundant, present nitrifiers. The fertilizer treatments had no effect on the alpha and beta diversities of the AOB communities. Interestingly, we found three clusters of co-varying variables with nitrifier operational taxonomic units (OTUs): the N2 O-producing AOB Nitrosospira with N2 O, NO3 - , NH4 + , water-filled pore space (WFPS) and pH; AOA Nitrososphaera with NO3 - , NH4 + and pH; and AOA Nitrososphaera and NOB Nitrospira with NH4 + , which suggests different drivers. These results support the co-occurrence of non-N2 O-producing Nitrososphaera and Nitrospira in the unfertilized soils and the promotion of N2 O-producing Nitrosospira under urea fertilization. Further, we suggest that DMPP is a more effective NI than DCD in tropical soil under sugarcane.
摘要:
硝化抑制剂(NIs)3,4-二甲基吡唑(DMPP)和双氯胺(DCD)可以有效减少N2O的排放;但是,哪些物种是目标,这些NIs对微生物硝化群落的影响尚不清楚。这里,我们确定了与N2O排放相关的氨氧化细菌(AOB)物种,并在甘蔗下进行了258天的田间试验,评估了尿素和尿素与DCD和DMPP对硝化群落的影响。使用amoAAOB扩增子测序方法并挖掘以前的16SrRNA序列数据集,我们将最可能产生N2O的AOB鉴定为亚硝基螺旋体。并鉴定了亚硝基螺旋体(AOB),Nitrososphaera(古细菌氨氧化剂)和Nitrospira(亚硝酸盐氧化剂)是最丰富的,目前的硝化。肥料处理对AOB群落的α和β多样性没有影响。有趣的是,我们发现了三个具有硝化操作分类单位(OTU)的共同变量簇:具有N2O的产生N2O的AOB亚硝基螺旋体,NO3-,NH4+,充满水的孔隙空间(WFPS)和pH;AOA含NO3-,NH4+和pH;以及AOA亚硝基螺旋体和NOB亚硝基螺旋体与NH4+,这表明不同的驱动程序。这些结果支持在未施肥的土壤中同时出现不产生N2O的亚硝基螺旋体和亚硝基螺旋体,并在尿素施肥下促进产生N2O的亚硝基螺旋体。Further,我们建议在甘蔗下的热带土壤中,DMPP比DCD更有效。