One-time nitrogen fertilization shifts switchgrass soil microbiomes within a context of larger spatial and temporal variation

Abstract

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.

Conservation of Endophyte Bacterial Community Structure Across Two Panicum Grass Species

“…However, the impact of site on the rhizosphere communities suggests that plants had time to recruit from their destination soils and/or show remaining legacy communities from their sites of origin. The impact of switchgrass cultivation on soils has been previously described (He et al, 2017; Chen et al, 2019). Hence our analyses focus more on general bacterial trends among P. virgatum and P. hallii genotypes and do not claim to be representative of a Panicum grass grown from seed in native soils.…”

“…Host ecotype-differentiation has been observed to impact and be impacted by the structure and function of the associated microbiomes (Bulgarelli et al, 2012; Laine et al, 2014). Few studies exist on microbial communities associated with switchgrass (Allgaier et al, 2010; Gladden et al, 2011; D’haeseleer et al, 2013; Gagne-Bourgue et al, 2013; Xia et al, 2013; Piao et al, 2014; He et al, 2017; Chen et al, 2019), and only fungal sequence data have been collected on P. hallii varieties (Giauque and Hawkes, 2016). In this study, we compared root endophytic and rhizosphere microbial community structure and diversity among plants representing both ecotypes in P. virgatum and P. hallii .…”

From Surface to Subsurface: Diversity, Composition, and Abundance of Sessile and Endolithic Bacterial, Archaeal, and Eukaryotic Communities in Sand, Clay and Rock Substrates in the Laurentians (Quebec, Canada)

“…The inconsistent pattern may suggest that site-specific characteristics are also important determinants for shaping the fungal communities. Further studies on the ecology of these diverse eukaryotic taxa in the shallow terrestrial subsurface are clearly needed [66].…”

Effect of nitrogen fertilization on central tendency and spatial heterogeneity of soil moisture, pH and dissolved organic carbon and nitrogen in two bioenergy croplands#

“…Nitrogen (N) fertilizers are widely used to increase yield of bioenergy crops (Behrman et al, 2013;Jung & Lal, 2011;Kiniry et al, 2013;Robertson et al, 2011;Smith et al, 2013), but their impacts on belowground soil physiochemical properties received attentions only in the recent decade. For instance, past studies examined N fertilization effects on SG soil aggregate stability, bulk density, phosphorus and potassium, soil organic carbon (SOC), microbial community abundance and composition (Chen et al, 2019;Krapfl et al, 2014;Lai et al, 2018;Li et al, 2018;Li, Jian, Lane, Guo, et al, 2020;Stewart et al, 2015;Valdez et al, 2017). Soil moisture, pH, dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) are of importance for plant growth, microbial activities, nutrients' turnover and ecosystem health (Ding et al, 2019;Moradizadeh & Srivastava, 2021).…”