show Abstracthide AbstractWe conducted a microcosm experiments with N treatments and 13C-CO2 labelling, using paddy soil samples from Jiangdu FACE station (Wuxi county, Jiangsu Province, China) in 2018. After incubation, we separated 13C-labelld DNA from 12C-labelled genomic DNA through isopycnic gradient ultracentrifugation and selected the heavy DNA gradients for metagenomic sequencing.