Soil microbiome responses to short-term nitrogen (N) inputs remain uncertain when compared with previous research that has focused on long-term fertilization responses. Here, we examined soil bacterial/archaeal and fungal communities pre- and post-N fertilization in an 8 year-old switchgrass field, in which twenty-four plots received N fertilization at three levels (0, 100, and 200 kg N ha -1 as NH 4 NO 3 ) for the first time since planting. Soils were collected at two depths, 0–5 and 5–15 cm, for DNA extraction and amplicon sequencing of 16S rRNA genes and ITS regions for assessment of microbial community composition. Baseline assessments prior to fertilization revealed no significant pre-existing divergence in either bacterial/archaeal or fungal communities across plots. The one-time N fertilizations increased switchgrass yields and tissue N content, and the added N was nearly completely removed from the soil of fertilized plots by the end of the growing season. Both bacterial/archaeal and fungal communities showed large spatial (by depth) and temporal variation (by season) within each plot, accounting for 17 and 12–22% of the variation as calculated from the Sq. root of PERMANOVA tests for bacterial/archaeal and fungal community composition, respectively. While N fertilization effects accounted for only ~4% of overall variation, some specific microbial groups, including the bacterial genus Pseudonocardia and the fungal genus Archaeorhizomyces , were notably repressed by fertilization at 200 kg N ha -1 . Bacterial groups varied with both depth in the soil profile and time of sampling, while temporal variability shaped the fungal community more significantly than vertical heterogeneity in the soil. These results suggest that short-term effects of N fertilization are significant but subtle, and other sources of variation will need to be carefully accounted for study designs including multiple intra-annual sampling dates, rather than one-time “snapshot” analyses that are common in the literature. Continued analyses of these trends over time with fertilization and management are needed to understand how these effects may persist or change over time.

We demonstrate the utility of a simple and fast methanol extraction method that achieves similar bisphenols recovery efficiencies from microbial culture suspensions and sediment material than more laborious and costly extraction procedures. The methanol extraction method may have broad application for the rapid analysis of hydrophobic compounds in biodegradation studies.

33Soil microbiome responses to short-term nitrogen (N) inputs within the context of existing 34 spatio-temporal variability remain uncertain. Here, we examined soil bacterial and fungal 35 communities pre/post-N fertilization in an 8 year-old switchgrass field, in which twenty-four 36 plots received N fertilization at three levels (0, 100, and 200 kg N ha -1 as NH 4 NO 3 ) for the first 37 time since planting. Soils were collected at two depths, 0-5 and 5-15 cm, for DNA extraction and 38 amplicon sequencing of 16S rRNA genes and ITS regions, and soil metagenomic analysis. 39Baseline assessment prior to fertilization revealed no pre-existing differences in either bacterial 40 or fungal communities across plots. The one-time N fertilization increased switchgrass yields 41 and tissue N content, and the added N was nearly completely removed from the soil of fertilized 42 plots by the end of the growing season. Both bacterial/archaeal and fungal communities showed 43 large spatial (by depth) and temporal variation (by season) within each plot, accounting for 17 44 and 12-22 % of the variation in bacterial/archaeal and fungal community composition, 45 respectively. While N fertilization effects accounted for only ~4% of overall variation, some 46 specific microbial groups, including the bacterial genus Pseudonocardia and the fungal genus 47 Archaeorhizomyces, were notably repressed by fertilization at 200 kg N ha -1 . Bacterial groups 48 varied with both depth in the soil profile and time of sampling, while temporal variability shaped 49 the fungal community more significantly than vertical heterogeneity in the soil. Thus, variability 50 within the field might override the changes induced by N addition. Continued analyses of these 51 trends over time with fertilization and management are needed to understand whether these 52 transient effects change over time.53 4 54 Introduction 55Cultivation of dedicated bioenergy crops is of interest to sustain long-term energy supplies [1]. 56 The International Energy Agency predicts that biofuels could satisfy more than a quarter of 57 world needs for transportation energy by 2050 [2]. Switchgrass (Panicum virgatum L.) has been 58 a prominent candidate as an energy crop due to its high biomass yield, low maintenance and 59 limited-input requirements [3], and high adaptability to marginal sites [4]. Such characteristics 60 may allow switchgrass for its use to reclaim degraded or abandoned agricultural lands while 61 reserving fertile lands for food production [5]. With its well developed and deep rooting systems, 62 switchgrass may also improve belowground carbon storage and nutrient acquisition [6] and 63 potentially moderate the diversity of below-ground and plant-associated microbiomes. Thus, how 64 switchgrass cultivation affects soil microbial communities and their interaction with crop yields 65 needs further investigation to understand the long-term ecosystem consequences and 66 sustainability of the cultivation of perennial crops, such as switchgrass.67