Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems

Media type: E-Article

Title: Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems

Contributor: Rodionov, Andrei [Author]; Bauke, Sara L. [Author]; von Sperber, Christian [Author]; Hoeschen, Carmen [Author]; Kandeler, Ellen [Author]; Kruse, Jens [Author]; Lewandowski, Hans [Author]; Marhan, Sven [Author]; Mueller, Carsten W. [Author]; Simon, Margaux [Author]; Tamburini, Federica [Author]; Uhlig, David [Author]; von Blanckenburg, Friedhelm [Author]; Lang, Friederike [Author]; Amelung, Wulf [Author]; Soil Ecology, University of Bayreuth, Bayreuth, Germany [Author]; Institute of Crop Science and Resource Conservation (INRES) – Soil Science and Soil Ecology, University of Bonn, Bonn, Germany [Author]; Department of Geography, McGill University, Montreal, Canada [Author]; Chair of Soil Science, Department of Ecology and Ecosystem Management, Technical University of Munich, Freising-Weihenstephan, Germany [Author]; Institute of Soil Science and Land Evaluation, Soil Biology Department, University of Hohenheim, Stuttgart, Germany [Author]; Institute of Bio- and Geosciences – Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, Jülich, Germany [Author]; Department of Geosciences and Natural Resource Management, Section for Geography, University of Copenhagen, Copenhagen, Denmark [Author]; Institute of Agricultural Sciences, ETH Zurich, Lindau, Switzerland [Author]; GFZ German Research Centre for Geosciences, Earth Surface Geochemistry, Potsdam, Germany [Author];

Published: Springer International Publishing, 2020-10-01

Language: English

DOI: https://doi.org/10.1007/s10533-020-00700-8

Keywords: XANES ; Microbial P cycling ; NanoSIMS ; Phosphate ; Oxygen isotopes ; Soil

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Description: Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient in total P stocks. We analyzed the oxygen isotopic composition of HCl-extractable phosphate (δ18OP) and identified differences in P speciation with increasing soil depth using X-ray absorption near-edge structure (XANES) spectroscopy. We further determined microbial oxygen demand with and without nutrient supply at different soil depths to analyse nutrient limitation of microbial growth and used nanoscale secondary ion mass spectrometry (NanoSIMS) to visualize spatial P gradients in the rhizosphere. We found that δ18OP values in the topsoil of all sites were close to the isotopic signal imparted by biological cycling when oxygen isotopes in phosphate are exchanged by enzymatic activity. However, with increasing soil depth and increasing HCl-P concentrations, δ18Ο values continuously decreased towards values expected for primary minerals in parent material at depths below 60 cm at sites with high subsoil P stocks and below more than 2 m at sites with low subsoil P stocks, respectively. For these depths, XANES spectra also indicated the presence of apatite. NanoSIMS images showed an enrichment of P in the rhizosphere in the topsoil of a site with high P stocks, while this P enrichment was absent at a site with low P stocks and in both subsoils. Addition of C, N and P alone or in combination revealed that microbial activity in subsoils of sites with low P stocks was mostly P limited, whereas sites with high P stocks indicated N limitation or N and P co-limitation. We conclude that subsoil P resources are recycled by trees and soil microorganisms. With continued weathering of the bedrock and mobilisation of P from the ...

Access State: Open Access

Rights information: Attribution (CC BY)

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