Skip to main content
Research article - Peer-reviewed, 2020

Microbial solubilization of silicon and phosphorus from bedrock in relation to abundance of phosphorus-solubilizing bacteria in temperate forest soils

Pastore, Giovanni; Kernchen, Sarmite; Spohn, Marie


Biogeochemical weathering of bedrock is the most important input of silicon (Si) and phosphorus (P) to forest ecosystems. While soil microbes, and in particular P-solubilizing bacteria (PSB), are known to accelerate the solubilization of Si and P from silicate rocks, our understanding of the mechanisms driving biogenic weathering are still limited. To fill this gap, incubation experiments with weathered parent materials (i.e. basalt, andesite and paragneiss) of four soils and water extracts of the four soils, differing in P stocks, were conducted. We found that the net Si solubilization rate ranged from 5.0 (+/- 1.8) to 91.0 (+/- 2.4) nmol m(-2) d(-1) across all examined soils. The silicate dissolution rates were negatively related to the decrease in pH (ApH) and positively related to the amounts of organic acids released by microbes. We found that the gross P solubilization rates from the parent materials were similar to 11 times higher at the P-rich site (BBR) compared to the P-poor site (CON). In addition, we determined the abundance and the taxonomic composition of PSB communities in the four soils. The abundance of PSB ranged from 2% at the P-rich site to 22.1% at the P-poor site, indicating that a selective pressure exists in P-poor soils towards a higher abundance of P-solubilizers. Yet, despite the relative high abundance of PSB, the gross P solubilization rates were low in the soils derived from P-poor parent material. The genus Pseudomonas was found only in the PSB community at the P-poor site. Burkholderiales and Bacillales together were by far the two most abundant orders among the PSB communities in all soils and depths. In conclusion, this study shows that PSB are more abundant in P-poor soil than in P-rich soil, while the weathering rate seems to be mostly dependent on the bedrock.


Biogenic rock weathering; Silicate weathering; P-solubilizing bacteria; Phosphorus solubilization; Silicon solubilization; Organic acids

Published in

Soil Biology and Biochemistry
2020, volume: 151, article number: 108050

Authors' information

Pastore, Giovanni
University of Bayreuth
Kernchen, Sarmite
University of Bayreuth
Spohn, Marie
Swedish University of Agricultural Sciences, Department of Soil and Environment
Spohn, Marie
University of Bayreuth

Sustainable Development Goals

SDG15 Life on land

UKÄ Subject classification

Soil Science

Publication Identifiers


URI (permanent link to this page)