『Abstract
Amending poultry litter with Al sulfate (alum) has proven effective
in reducing water-soluble P in the litter and in runoff from fields
that have received litter applications. Although its effectiveness
has been demonstrated on a macroscopic scale in the field or in
the poultry houses, litter is known about P speciation in either
alum-amended or unamended litter. This knowledge is important
for the evaluation of long-term stability and bioavailability
of P, which is a necessary prerequisite for the assessment of
the sustainability of intensive poultry operations. Here we report
results from an investigation of alum-amended poultry litter (PL)
that combined a chemical extraction sequence with solid-state
31P nuclear magnetic resonance (NMR) spectroscopic
analysis of the residues. Aluminum is predominantly found in the
fine size separate (＜125μm), indicating that the alum added to
the poultry houses hydrolyzed without being completely dispersed
in the litter. The NMR spectra confirmed the hypothesis that calcium
phosphate phases are only dissolved during extraction with dilute
acid and phosphate associated with Al is mainly dissolved during
extraction with NaOH. Extraction of phosphate associated with
Al was incomplete, however, as evidenced by 31P NMR
spectroscopy. It could also be demonstrated that the extraction
sequence overestimates the calcium phosphate fraction by an order
of magnitude in this particular sample. Results from sequential
chemical extraction should therefore be used with caution when
assessing the magnitude of different phosphate pools in poultry
litter.』
Abbreviations
(Introduction)
Materials and methods
Sample preparation and extraction
Nuclear magnetic resonance experiments
Results and discussion
Total concentrations of phosphorus, calcium, aluminum, and
iron in the size separates
Sequential extraction
Phosphorus-31 nuclear magnetic resonance spectroscopy
Comparison of the quantification by extraction and phosphorus-31
nuclear magnetic resonance
Conclusions
Acknowledgments
References