Soil microbiota under N rate and crop rotation treatment, 2015-2016, Illinois

This study sought to identify bacterial, archeal, and fungal indicators of the soil environment under N fertilization rates and crop rotation treatments in typical US Midwestern Mollisols in Illinois. The plots were arranged as a split-plot of rotation (continuous corn, CCC; corn-soybean rotation, CS) and N fertilization rates (0, 202, 269 kg N/ha) in a randomized complete block design with three replicates. The rotation treatment was the main plot and N fertilization treatment was the subplots. Both rotation and N fertilization rate treatments began in 1981, while N was fertilized as urea (46%N) until 1996, and as urea ammonium nitrate solution (UAN 28%) since then. The soil samples were taken in October of 2015 and in 2016 after harvest. Each year, three composited soil subsamples to a depth of 10 cm were taken with Eijelkamp grass plot sampler within each experimental unit. Soil DNA was extracted using PowerSoil DNA isolation kits (MoBio Inc., Carlsbad, CA, USA) from 0.25g of the composited soil samples, following the manufacturer's instructions. The DNA samples were sequenced at the W.M. Keck Center for Comparative and Functional Genomics at the University of Illinois Biotechnology Center (Urbana, IL, USA) using paired-end sequencing on the Illumina MiSeq system (Illumina, San Diego, CA, USA).