Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/23/2014
Publication Date: N/A
Technical Abstract: The effect of manure application soil phosphorus (P) has been intensively studied with modifications of the Hedley sequential fractionation procedure, X-ray absorption near-edge structure spectroscopy, and 31P-nuclear magnetic resonance. Modern sequential fractionation techniques, coupled with phosphatase hydrolysis, have recently allowed for greater understanding of manure effects on soil P distribution. We evaluated the effect of long-term (> 10 years) poultry litter (broiler and turkey litter) application (4.5, 6.7, 9.0, 11.2, and 13.4 Mg manure per ha) on P in watershed-scale plots (cultivated and grazed/ungrazed pasture) near Riesel, Texas. Soil inorganic P (Pi) and organic P (Po) were quantified by sequential extraction (H2O, NaHCO3, NaOH, and HCl) and hydrolysis with acid phosphomonoesterase, nuclease P1, and 3-phytase (Pe). Litter application increased the total extractable P (Pt) in all plots, regardless of land-use type; application at 13.4 Mg/ha increased Pt in cropland and pasture by 23- and 8-fold, respectively. Compared to control, H2O-Pi from litter-amended plots increased by 9 to 34-fold (cultivated), and 7- to 30-fold (pasture), indicating substantial risk of soluble P runoff. Most labile Po (extracted with H2O and NaHCO3) was monoester-like, and decreased in the order of monoester > nucleic acid > phytate > non-hydrolysable organic P (Pne). Litter application did not affect NaOH-Pi or NaOH-Pe (P > 0.05), but increased NaOH-Pne: the general composition was Pi > monoester > phytate > nucleic acid > Pne. An average of 68% of Pt was extractable with HCl. The HCl-P composition was predominantly (95%) Po, and increased 2- to 3-fold by high rates of litter application in cultivated and grassed plots, respectively. Only trace levels of HCl-Pe were found; however, litter application increased HCl-Pne by 1- to 3-fold. Thus, repeated litter application increased levels of both soluble Pi and stable, non-hydrolysable Po, but specific response varied with application rate and land management.