Poultry diet modification studies have evaluated the effect of altering phosphorus (P) sources, forms, and amendments on poultry performance and P excretion.  In one particular study, broiler breeders were fed available P rations at standard and reduced rates of non-phytate P (NPP) with and without the addition of phytase.  Manure of the standard and the reduced NPP diets yielded 21.7 and 15.7 g P kg dry manure^-1 where calcium (Ca) concentrations were not different.  However, standard diet yielded lower Ca:P than the reduced NPP diet, (5.0 and 7.0, respectively).  This study examined P availability to corn at rates of 7.5, 15, 30 and 60 mg of total P kg^-1 for the low and the high Ca:P broiler breeder manures and triple superphosphate (TSP).  Height and leaf area were not different among P sources at the same rates.  Greater P rate hasten node development at 30 and 60 mg P kg^-1.  Shoot:root was lowest for high Ca:P manure at 30 and 60 mg P kg^-1 due to the greater root dry matter accumulation.  Few differences in leaf and stalk dry matter accumulations were exhibited among P sources.  Enhanced root development was linked to greater Ca uptake with high Ca:P manure.  Whole plant P uptake was significantly greater for the two manures than TSP at the rate of 60 mg P kg^-1.  Whereas, water soluble P in the soil was 0.85 mg P kg ^-1 greater for TSP than for high Ca:P at 60 mg P kg^-1.  Soil pH increased as P rate increased for both manures, where high Ca:P manure was higher than the untreated control and TSP at 60 mg P kg^-1 (6.3 vs. 5.75 and 5.90, respectively).  Future research will evaluate P transformation of soils amended with manures of variable Ca:P ratios as related to environmental concerns and bioavailability.