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).

本研究旨在识别在伊利诺伊州典型的美国中西部的Mollisols土壤中，受氮肥施用量和作物轮作处理影响的细菌、古菌和真菌指标。实验地块按照轮作（连续玉米，CCC；玉米-大豆轮作，CS）和氮肥施用量（0，202，269公斤氮/公顷）的随机完全区组设计，分为三组重复。轮作处理为主区组，氮肥施用量处理为副区组。两种处理均始于1981年，至1996年之前使用尿素（46%氮）施肥，此后则使用尿素硝酸铵溶液（UAN 28%）。土壤样本于2015年10月及2016年收获后采集。每年，在每个实验单元内，使用Eijelkamp草地采样器采集三个混合土壤子样本，深度为10厘米。从混合土壤样本的0.25克中，采用PowerSoil DNA提取试剂盒（MoBio Inc.，卡尔斯巴德，加利福尼亚州，美国）提取土壤DNA，按照制造商的说明进行。DNA样本在伊利诺伊大学生物技术中心（Urbana，伊利诺伊州，美国）的W.M. Keck比较与功能基因组学中心使用Illumina MiSeq系统（Illumina，圣地亚哥，加利福尼亚州，美国）进行双端测序。