Title: Phosphate speciation in excessively fertilized soil: A P-31 and Al-27 MAS NMR spectroscopy study
Authors: Lookman, R ×
Geerts, H
Grobet, Pierre
Merckx, Roel
Vlassak, Karel #
Issue Date: 1996
Publisher: Blackwell science ltd
Series Title: European journal of soil science vol:47 issue:1 pages:125-130
Abstract: Both P and Al MAS NMR spectra of samples of excessively fertilized sandy soil provided information about the P and Al speciation. Peak deconvolution was used to interpret reliably acid quantitatively the P-31 NMR spectra recorded. Most of the P was found to be associated with Al. Part of the P exhibited a chemical shift that could be attributed to octocalcium phosphate, amorphous calcium phosphate or apatite. Apatite has, however, never been reported to occur in sandy soils of temperate climates. A dithionite extraction used to remove interfering Fe from the samples also removed most of the octahedral AI-P phase. After oxalate extraction more than 99% of the original P signal disappeared. About 7.5 to 11% of the total oxalate extractable P of the excessively fertilized soil was present as a Ca-P phase, even though these soils are slightly acid to acid. The estimated size of the Ca-P phase roughly corresponds to the size of the labile P pool of these soils, as assessed in long-term batch desorption experiments. It still remains unclear whether the labile P pool should be attributed solely to such a Ca-P phase.
ISSN: 1351-0754
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Surface Chemistry and Catalysis
Division Soil and Water Management
× corresponding author
# (joint) last author

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