Evidence for struvite in poultry litter: effect of storage and drying.
The use of spectroscopic techniques (especially phosphorus-31 nuclear magnetic resonance [(31)P-NMR] and X-ray absorption near edge structure spectroscopy) has recently advanced the analysis of the speciation of P in poultry litter (PL) and greatly enhanced our understanding of changes in P pools in PL that receive alum (aluminum sulfate) to reduce water-soluble P and control ammonia emissions from poultry houses. Questions remain concerning changes of P species during long-term storage, drying, or after application of PL to cropland or for other uses, such as turfgrass. In this study, we investigated a set of six PL samples (of which three were alum-amended and three were unamended) that had been characterized previously. The P speciation was analyzed using solid-state (31)P-NMR spectroscopy, and the mineralogy was analyzed by powder X-ray diffraction (XRD) after storing the samples moist and dried for up to 5 yr under controlled conditions. The magnesium ammonium phosphate mineral struvite was identified in all but one PL samples. Struvite concentrations were generally lower in dried samples (< or = 14%) than in samples stored moist (23 and 26%). The moist samples also had higher concentrations of phosphate bound to aluminum hydroxides. Solid-state NMR spectroscopy was in general more sensitive than XRD in detecting and quantifying P species. Although phosphate associated with calcium and aluminum made up a large proportion of P species, they were not detected by XRD.
Dep. of Earth and Environment, Univ. of Leeds, Leeds LS2 9JT, UK. s.hunger@earth.leeds.ac.uk
Stefan
S
Hunger
J Thomas
JT
Sims
Donald L
DL
Sparks
D000818:Animals; D017616:Magnesium Compounds / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D008372:Manure / Q000032:analysis*; D010710:Phosphates / Q000032:analysis*; D010758:Phosphorus / Q000032:analysis; D011200:Poultry; D000069877:Struvite; D014961:X-Ray Diffraction
D017616:Magnesium Compounds; D008372:Manure; D010710:Phosphates; D010758:Phosphorus; D000069877:Struvite