16S rRNA gene amplicon sequencing of paddy soil microcosms originating from Vercelli (Italy)

Nitrogen fertilizer application in paddy soils lowers the mobility of the toxic metalloid arsenic but at the same time leads to greater greenhouse gas emissions compared to non-fertilized paddy soils. Paddy soil samples were collected in October 2020 in Vercelli, Italy, which is located in the Po river plain in the region of Piedmont. The sampled paddy field is located on the Cascina Boraso research farm at the international rice research institute (CREA-CI). Paddy soil samples were taken after removal of the plant layer from the upper 20 cm at three different locations across the paddy field. For microcosms, 25g fresh paddy soil was pre-incubated 18 days, then subjected to different N fertilization regimes (control: no N addition, high: 200 mg N kg-1 soil-1) by the addition of KNO3 solution. The microbial community composition was investigated after 37 days incubation (25C in the dark). Microbial 16S rRNA genes were amplified using primers 515F and 806R targeting the V4 region, and subsequently library preparation with Nextera (Illumina) 2nd step PCR and sequencing on Illumina MiSeq, v2, 2x250 bp were performed by Microsynth AG (Switzerland).