Availability of Residual Phosphorus From Broiler Litter Ash and Layer Manure Ash Amended Soil for Paspalum Vaginatum Uptake.

It has been hypothesized by several scientists that poultry litter ash (PLA) could be used as a slow release phosphorus fertilizer.  To test this hypothesis a greenhouse study was conducted using a broiler litter ash (BLA), layer manure ash (LMA), and calcium phosphate  (Ca-P) to determine phosphorus availability for Paspalum (Paspalum vaginatum) after consecutive cropping with corn (Zea Mays), wheat (Triticum aestivum) and soybean [Glycine max (L.) Merr].  Paspalum is a salt tolerant, low fertility demand grass that can withstand repeated clippings. Broiler litter ash, layer manure ash and calcium phosphate were applied at two rates (40 and 80 mg P kg^-1) to a low fertility silt loam soil (Beltsville series) replicated four times.  After the third crop (soybean), a Mehlich-3 soil extraction was performed to determine P levels. In order to determine if residual P from the PLA become available over time, four pre-rooted Paspalum cuttings were planted in each pot and fertilized with100 kg ha^-1 nitrogen as potassium and magnesium nitrate.  Plants were harvested, 8, 14 and 18 weeks after planting.  Paspalum yields were higher for plants grown on the poultry litter ash compared to the control and calcium phosphate treatments, however, only for the broiler litter ash treatment was the yield significantly different.  Phosphorus concentration in the Paspalum tissue will be presented.