Thursday, November 16, 2006 - 10:30 AM

Mineralization of Phosphorus from Pelletized Manure Under Broiler-Breeder Diet Modification.

Shaun Casteel, Rory Maguire, John Brake, Daniel W. Israel, Carl Crozier, and Peter Plumstead. NC State Univ, Dept of Soil Science, Campus Box 7619, Raleigh, NC 27695

Poultry manure is high in total P and is often land applied at rates above crop P removal. Such applications and concentrated areas of poultry production have increased soil P levels, which raise environmental concerns. Previous studies have evaluated modifying poultry diet to reduce P excretion. A broiler-breeder diet study examined a standard and a reduced available P rate via non-phytate P (NPP) ration alone and a reduced NPP ration amended with phytase. The four resulting manures were collected and pelletized for soil mineralization and crop response studies. This study examines the P mineralization rate of the four manures at 30 and 60 mg of total P/kg of dry soil in two low P soils. Portsmouth fine sandy loam was collected from a long term fertility study in Plymouth NC, and Wagram loamy sand was collected in a forested area at Clayton NC. An untreated control was included to account for endogenous P mineralization of the respective soils. Experimental design was a RCBD with three replications. Soil was maintained at 60% container capacity (16% moisture) and 25°C for 12 weeks.  Subsamples were taken at week 0, 1, 2, 4, 8 and 12, and were analyzed for water soluble P, total P, total inorganic P, Mehlich-3 nutrients, C:N, and pH.