Saturday, 15 July 2006

Speciation of Phosphorus in Manures and Manure-Amended Soils.

Babasola Ajiboye1, Olalekan Akinremi1, and Yongfeng Hu2. (1) Univ of Manitoba, Dept of Soil Science, 362 Ellis Building, Winnipeg, MB R3T2N2, Canada, (2) Canadian Light Source Inc., 101 Perimeter Road, Univ of Saskatchewan, Saskatoon, SK S7N 0X4, Canada

From an environmental standpoint, the forms of Phosphorus (P) in organic amendments and the resulting compounds when they are applied to the soil are crucial in determining the risk of P loss to water bodies. Molecular scale speciation of P in organic amendments and soils is one of the major advances made possible by Synchrotron Radiation (SR) techniques. SR-based technique such as X-ray Absorption Spectroscopy (XAS) is an improvement over the conventional chemical extraction characterization of P because minimal sample preparation is required and the possibility of transforming P species with extractants is eliminated. This experiment was carried out to identify the P species in samples that had been previously characterized by sequential chemical extraction methods. Freeze-dried samples of biosolids, hog, dairy and beef manures, and poultry litters and air-dried calcareous soils amended with these manures were used. Phosphorus K-edge X-ray Absorption Near Edge Structure (XANES) spectra of organic amendments and soils, and various reference phosphate standards covering iron, aluminum, calcium, magnesium, ammonium, and organic phosphates were acquired on the Double Crystal Monochromator (DCM) beamline of CSRF at the SRC facility of University of Wisconsin-Madison. Both Fluorescence Yield (FY) and Total Electron Yield (TEY) were recorded for all samples. Preliminary analysis using ‘fingerprinting', Principal Component Analysis (PCA) and Linear Combination (LC) approaches on the FY data showed that organic P, calcium-, and aluminum phosphates were the dominant phosphates in biosolids and manures, while organic P, calcium-, and iron phosphates were the dominant species in the amended soils.

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