sequences of bacteria
454-pyrosequencing was used to investigated community of AOB, AOA, bacteria, and archaea in the soils. The cluster of operational taxonomic units (OTUs) was conducted using Quantitative Insight Into Microbial Ecology (QIIME) (http://qiime.org/) took kit at a similarity of 97%, followed by the reservation for the longest sequence in OTUs as representative sequence.