Long-term nitrogen fertilization alters microbial community structure and denitrifier abundance in the deep vadose zone

Amplicon sequencing and quantitative PCR analyses were performed to profile the vertical distribution of soil microbial communities and denitrification genes.The soil microbial community structure and diversity were strongly influenced by soil depth and N fertilization.

The 250 cm depth was identified as a threshold depth, as dramatically different microbial communities were found below and above this depth.Quantitative PCR results showed that the absolute abundance of denitrification genes decreased with increasing soil depth.This study elucidated the profound effects of long-term N input on the composition and diversity of the microbial communities and the abundance of denitrifiers in the deep vadose zone.