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Phosphorus speciation in cultivated organic soils revealed by P K-edge XANES spectroscopy

Schmieder, Frank and Gustafsson, Jon-Petter and Klysubun, Wantana and Zehetner, Franz and Riddle, Matthew and Kirchmann, Holger and Bergström, Lars (2020). Phosphorus speciation in cultivated organic soils revealed by P K-edge XANES spectroscopy. Journal of Plant Nutrition and Soil Science. 183 , 367-381
[Journal article]

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Abstract

Cultivated organic soils make a significant contribution to phosphorus (P) leaching losses from agricultural land, despite occupying a small proportion of cultivated area. However, less is known about P mobilisation processes and the P forms present in peat soils compared with mineral soils. In this study, P forms and their distribution with depth were investigated in two cultivated Histosol profiles, using a combination of wet chemical extraction and P K-edge X-ray absorption near-edge structure (XANES) spectroscopy.Both profiles had elevated P content in the topsoil, amounting to around 40 mmol kg(-1), and P speciation in both profiles was strongly dominated by organic P. Topsoils were particularly rich in organic P (P-org), with relative proportions of up to 80%. Inorganic P in the profiles was almost exclusively adsorbed to surface reactive aluminium (Al) and iron (Fe) minerals. In one of the pro-files, small contributions of Ca-phosphates were detected.A commonly used P saturation index (PSI) based on ammonium-oxalate extraction indicated a low to moderate risk of P leaching from both profiles. However, the capacity of soil Al and Fe to retain P in organic soils could be reduced by high competition from organic compounds for sorption sites. This is not directly accounted for in PSI and similar indices.Accumulation of P-org in the topsoil may be attributable by microbial peat decomposition and transformation of mineral fertiliser P by both microbiota and crops. Moreover, high carbon-phosphorus ratio in the surface peat material in both profiles suggests reduced net mineralisation of P-org in the two soils. However, advancing microbial peat decomposition will eventually lead to complete loss of peat horizons and to mineralisation of P-org. Hence, P-org in both profiles represents a huge potentially mobilised P pool.

Authors/Creators:Schmieder, Frank and Gustafsson, Jon-Petter and Klysubun, Wantana and Zehetner, Franz and Riddle, Matthew and Kirchmann, Holger and Bergström, Lars
Title:Phosphorus speciation in cultivated organic soils revealed by P K-edge XANES spectroscopy
Year of publishing :2020
Volume:183
Page range:367-381
Number of Pages:15
Publisher:Wiley-VCH Verlag GmbH & Co
ISSN:1436-8730
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution-Noncommercial-No Derivative Works 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Keywords:Histosol, organic phosphorus, phosphorus saturation, soil aluminium, soil iron, X-ray absorption spectroscopy
URN:NBN:urn:nbn:se:slu:epsilon-p-105698
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-105698
Additional ID:
Type of IDID
DOI10.1002/jpln.201900129
Web of Science (WoS)000530694400001
ID Code:17253
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: SLUpub Connector
Deposited On:18 Aug 2020 06:36
Metadata Last Modified:18 Aug 2020 06:36

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