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Please use this identifier to cite or link to this item: http://hdl.handle.net/1993/2812

Title: Molecular speciation of phosphorus in organic amendments and amended soils using nuclear magnetic resonance and X-ray absorption spectroscopies
Authors: Ajiboye, Babasola
Supervisor: Akinremi, Olalekan O. (Soil Science)
Examining Committee: Zhang, Tiequan Q. (Agriculture and Agri-Food Canada, Soil Fertility and Root Ecology) Kroeker, Scott (Chemistry) Flaten, Donald N. (Soil Science)
Graduation Date: October 2007
Keywords: P K-XANES
Solution P-31 NMR
Sequential extraction
Phosphorus
Waste Management
Soil Chemical Analysis
Synchrotron Radiation
Issue Date: 14-Sep-2007
Citation: Ajiboye, B et. al. (2007). Experimental validation of quantitative XANES analysis for P speciation. Soil Sci. Soc. Am J. Vol. 71:
Ajiboye, B. et al. (2007). Speciation of P in sequential extracts of organic amendments using NMR and XANES spectroscopies. J. Environ. Qual. (In Press)
Abstract: Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated ‘soluble and adsorbed P’ as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present in appreciable amount only in the control. Overall, the combination of techniques used in these studies improved the understanding of P species in organic amendments and amended soils that would not have been possible with any individual technique. Technological advances in P analysis should therefore be combined with conventional chemical extraction techniques to determine the fate of P in the environment.
URI: http://hdl.handle.net/1993/2812
Appears in Collection(s):FGS - Electronic Theses & Dissertations (Public)
Manitoba Heritage Theses

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