The effects of soil depth on the structure of microbial communities in agricultural soils in Iowa, USA

Abstract

17 The determination of how microbial community structure changes within the soil profile, 18 will be beneficial to understanding the long-term health of agricultural soil ecosystems 19 and will provide a first step towards elucidating how deep soil microbial communities 20 contribute to carbon sequestration. This study aimed to investigate the differences in the 21 microbial community abundance, composition and diversity throughout from the surface 22 layers down to deep soils in corn and soybean fields in Iowa, USA. We used 16S rRNA 23 amplicon sequencing of soil samples to characterize the change in microbial community 24 structure. Our results revealed decreased richness and diversity in bacterial community 25 structure with increasing soil depth. We also observed distinct distribution patterns of 26 bacterial community composition along soil profiles. Soil and root data at different 27 depths enabled us to demonstrate that the soil organic matter, soil bulk density and 28 plant water availability were all significant factors in explaining the variation in soil 29 microbial community composition. Our findings provide valuable insights in the changes 30 in microbial community structure to depths of 180 cm in one of the most productive 31 agricultural regions in the world. This knowledge will be important for future 32 management and productivity of agroecosystems in the face of increasing demand for 33 food and climate change. 34 35 36

Soil pH: a key edaphic factor regulating distribution and functions of bacterial community along vertical soil profiles in red soil of pomelo orchard

“…2 ). These findings are in concordance with the previous studies that soil depth plays an important role to shape the soil bacterial communities owing to differences in soil properties [ 7 , 37 ]. Although soil properties (e.g., pH, AP, AK, AN) along different soil depths varied from each other but resulted in a high percentage of the shared OTUs accounted for 93.8% of total reads and it implies that similarity of bacterial community composition was high along the soil gradient.…”

“…For instance, the relative abundance of Acidobacteria and Actinobacteria varied throughout the soil depth in one previous study [ 43 ]. However, we found that the RA of Acidobacteria was decreased with increasing soil depth, whereas Actinobacteria RA was at the peak in RS3 (40–60 cm), and consistent with the previous results where similar trends were observed in agricultural soils of Iowa, USA [ 7 ].…”

“…Their community composition, spatial patterns, and functional profiling have yet to be well investigated in the red soil of pomelo orchards. Recent researches of soil microbial biodiversity and long-term fertilizer studies have revealed that soil bacterial diversity is significantly affected by the soil depth and edaphic factors that shape the soil bacterial community [ 7 ]. For example, soil pH is a primary determinant of microbial community composition and functional diversity [ 31 , 36 ].…”

“…Despite the widespread occurrence of soil microbiota in different soil depths, the current knowledge about the distribution of soil microbes is limited to surface soil (0—20 cm) [ 7 ] owing to higher contents of soil organic matter, mineral nutrients, and rich in microbial diversity compared with subsurface soil [ 8 ]. Various studies have investigated the microbial diversity and community composition in the surface and subsurface soils, e.g., in paddy soils or Alaskan soil cores [ 9 – 11 ].…”

High‐resolution phenotyping of sorghum genotypic and phenotypic responses to low nitrogen and synthetic microbial communities

“…To study the bacterial communities in the rhizosphere and root endosphere collected from greenhouse experiment three, the V4 region of the 16S rRNA gene was amplified and sequenced with Illumina MiSeq platform using the protocol described in Hao et al (2021). The resulting sequencing data were processed and analysed using the UPARSE pipeline (Edgar, 2013) and QIIME (version 1.9.1 and 2) (Bolyen et al, 2019;Caporaso et al, 2010).…”