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Title: Phosphorus Speciation in Manure and Manure-Amended Soils Using XANES Spectroscopy

Previous studies suggested an increase in the proportion of calcium phosphates (CaP) of the total phosphorus (P) pool in soils with a long-term poultry manure application history versus those with no or limited application histories. To understand and predict long-term P accumulation and release dynamics in these highly amended soils, it is important to understand what specific P species are being formed. We assessed forms of CaP formed in poultry manure and originally acidic soil in response to different lengths of mostly poultry manure applications using P K-edge X-ray absorption near-edge structure (XANES) spectroscopy. Phosphorus K-edge XANES spectra of poultry manure showed no evidences of crystalline P minerals but dominance of soluble CaP species and free and weakly bound phosphates (aqueous phosphate and phosphate adsorbed on soil minerals). Phosphate in an unamended neighboring forest soil (pH 4.3) was mainly associated with iron (Fe) compounds such as strengite and Fe-oxides. Soils with a short-term manure history contained both Fe-associated phosphates and soluble CaP species such as dibasic calcium phosphate (DCP) and amorphous calcium phosphate (ACP). Long-term manure application resulted in a dominance of CaP forms confirming our earlier results obtained with sequential extractions, and a transformation from soluble to more stablemore » CaP species such as {beta}-tricalcium calcium phosphate (TCP). Even after long-term manure application (>25 yr and total P in soil up to 13 307 mg kg{sup -1}), however, none of the manure-amended soils showed the presence of crystalline CaP. With a reduction or elimination of poultry manure application to naturally acidic soils, the pH of the soil is likely to decrease, thereby increasing the solubility of Ca-bonded inorganic P minerals. Maintaining a high pH is therefore an important strategy to minimize P leaching in these soils.« less
Authors:
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Publication Date:
OSTI Identifier:
913821
Report Number(s):
BNL--78389-2007-JA
Journal ID: ISSN 0013-936X; ESTHAG; TRN: US200804%%230
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environ. Sci. Tech.; Journal Volume: 39; Journal Issue: 19
Research Org:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org:
Doe - Office Of Science
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; ABSORPTION; CALCIUM PHOSPHATES; FORESTS; IRON; LEACHING; MANURES; PHOSPHATES; PHOSPHORUS; SOILS; SOLUBILITY; SPECTRA; SPECTROSCOPY; TRANSFORMATIONS national synchrotron light source