Direct Speciation of Phosphorus in Alum-Amended Poultry Litter:  Solid-State ³¹P NMR Investigation

Abstract

Amending poultry litter (PL) with aluminum sulfate (alum) has proven to be effective in reducing water-soluble phosphorus (P) in the litter and in runoff from fields that have received PL applications; it has therefore been suggested as a best management practice. Although its effectiveness has been demonstrated on a macroscopic scale in the field, little is known about P speciation in either alum-amended or unamended litter. This knowledge is important forthe evaluation of the long-term stability and bioavailability of P, which is a necessary prerequisite forthe assessment of the sustainability of intensive poultry operations. Both solid-state MAS and CP-MAS 31P NMR as well as 31P[27Al]-TRAPDOR were used to investigate P speciation in alum-amended and unamended PL. The results indicate the presence of a complex mixture of organic and inorganic orthophosphate phases. A calcium phosphate phase, probably a surface precipitate on calcium carbonate, could be identified in both unamended and alum-amended PL, as well as physically bound HPO4(2-). Phosphate associated with Al was found in the alum-amended PL, most probably a mixture of a poorly ordered wavellite and phosphate surface complexes on aluminum hydroxide that had been formed by the hydrolysis of alum. However, a complex mixture of organic and inorganic phosphate species could not be resolved. Phosphate associated with Al comprised on average 40 +/- 14% of the total P in alum-amended PL, whereas calcium phosphate phases comprised on average 7 +/- 4% in the alum-amended PL and 14 +/- 5% in the unamended PL.

Pyrolysis temperature affects phosphorus transformation in biochar: Chemical fractionation and 31P NMR analysis

“…Chemical shifts were compared with those reported in literature to identify the P species and compounds (Cade-Menun et al, 2005). We assumed that peaks in NMR represented all P species in biochar, and we calculated the proportion and the content of those identified by NMR (Hunger et al, 2004;McDowell et al, 2002). Peak area was calculated by integration.…”

Phosphorus Compounds in Sequential Extracts of Animal Manures: Chemical Speciation and a Novel Fractionation Procedure

“…Solid-state 31P NMR spectroscopy was used recently to investigate phosphorus speciation in poultry litter (23) but is relatively insensitive and is unable to identify organic phosphates. In contrast, solution 31P NMR spectroscopy offers the most convenient way to speciate phosphorus in manure extracts, because multiple phosphorus compounds can be quantified simultaneously with minimal sample preparation and handling (24).…”

Phosphorus Desorption Dynamics in Soil and the Link to a Dynamic Concept of Bioavailability

“…While alum amended litter (Al-lit) releases significantly less P to runoff and leachate, the P retention mechanism is not fully understood. Hunger et al (2004) and Peak et al (2002) have provided direct observations of P speciation in these systems, using nuclear magnetic resonance (NMR) and x-ray absorption near edge structure (XANES) spectroscopy. Both studies showed the importance of aluminium surfaces as P sinks in alum amended PL.…”