Effects of nitrogen reduction on community structure and diversity of denitrifying bacteria in wheat-maize rotation farmland
To provide technical support for nitrogen fertilizer management in wheat-maize rotation farmland in North China Region,we investigated the effects of nitrogen reduction on the community structure and diversity of denitrifying bacteria communities.With no nitrogen application as control(CK),two nitrogen application rates were set,namely the conventional nitrogen application rate(300 kg·hm-2,N2)and nitrogen reduction rate of 20% (240 kg·hm-2,N1).Thereafter,soil DNA was extracted,amplified with nirS and nirK primers,and MiSeq PE300 sequencing technology was subsequently used to study the effects of nitrogen application rate on soil properties and nirS and nirK denitrifying bacteria community diversity in wheat-maize rotation farmland.The results demonstrated that,no significant difference in the α-diversity index of nirS and nirK denitrifying bacteria was observed among the three treatments,and the α-diversity of nirS denitrifying bacteria was higher than that of nirK.Nitrogen reduction significantly affected the species composition of nirS and nirK denitrifying bacteria.Moreover,it had no significant effect on the phylum level species composition of nirS and nirK denitrifying bacteria and the class level species composition of nirK denitrifying bacteria,but significantly reduced the relative abundance of Deltaproteobacteria of nirS denitrifying bacteria.Further,it significantly affected the genus level species composition of nirS and nirK denitrifying bacteria.Nitrate nitrogen,available phosphorus,and pH were the main soil environmental factors affecting the community structure of nirS denitrifying bacteria.pH value was the main soil environmental factor affecting the community structure of nirK denitrifying bacteria.In conclusion,moderate nitrogen reduction did not affect the α-diversity of denitrifying bacteria,but it significantly affected the community composition and structure of denitrifying bacteria at the genus level;thus,nitrogen reduction mainly affects N2O emission in farmland soil by affecting soil properties and microbial community structure.
nitrogen reductionnirKnirSdenitrifying bacteriawheat and maize rotationdiversitycommunity structure
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