Altered bacterial communities in long-term no-till soils associated with stratification of soluble aluminum and soil pH

Authors: LEWIS, RICKY - Washington State University; BARTH, VICTORIA - US Department Of Agriculture (USDA); COFFEY, TODD - Washington State University; MCFARLAND, CAROL - Washington State University; Huggins, David; SULLIVAN, TARAH - Washington State University

Submitted to: Soil Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2018
Publication Date: 2/5/2018
Citation: Lewis, R.W., Barth, V.P., Coffey, T., Mcfarland, C., Huggins, D.R., Sullivan, T.S. 2018. Altered bacterial communities in long-term no-till soils associated with stratification of soluble aluminum and soil pH. Soil Systems. 2(1):1-13. https://doi:10.3390/soils2010007.
DOI: https://doi.org/10.3390/soils2010007

Interpretive Summary: Soil acidification is a global issue that often results in increased aluminum (Al) toxicity to crops. While no-till (NT) management has many benefits regarding sustainability, a zone of soil acidification often occurs when nitrogen fertilizers are placed below the seed. The impacts of this acidity in NT on soil bacterial communities are largely unknown. We found that the bacterial communities in locations where soil was acid indicated that the soil was degraded as compared to other parts of the soil. Here important soil processes such as nutrient use and organic matter cycling would be negatively impacted particularly for crop seed germination and seedling growth. These results will be useful for producers, NRCS, Conservation Districts and scientists interested in soil acidity impacts on soil health and soil microbial communities.

Technical Abstract: Soil acidification is a global issue that often results in increased aluminum (Al) toxicity. While no-till (NT) management has many benefits regarding sustainability, a discrete zone of acidification often occurs when ammoniacal fertilizers are banded below the seed. The full agroecological consequences of NT stratification and impacts on bacterial communities are largely unknown. Using next-generation sequencing (NGS) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt), we characterized the influence of liming amendment and soil stratification on bacterial community composition and predicted function in 2-cm depth increments. Soil depth, pH, DTPA extractable aluminum (DTPA-Al), and KCl extractable Al (KCl-Al) were all significantly correlated with bacterial community structure and function. In soils with the lowest pH and greatest extractable Al, bacterial community was distinct, with highest relative abundance of the Koribacteraceae family, an indicator of soil degradation. Additionally, aspects of bacterial metabolism and nutrient turnover were impacted in the lowest pH zones, including secondary metabolite, carbohydrate, and energy metabolism. These results suggest that soil stratification (Al and pH) in NT systems has direct impacts on microbial community structure and function, potentially influencing ecosystem services at a highly resolved spatial scale within surface depths relevant to seed germination and emergence.