Two experiments were conducted during the two successive seasons of  2001/2002 and 2002/2003 at a private farm near El-Mansoura -Dakahlia Governorate, Egypt to investigate the effect of  mineral fertilizers, organic fertilizers (i.e. compost , rock phosphate ) and phosphorus  soluble bacteria (PSB) (Bacillus megaterium var. Phosphatium) on the plant growth, yield, and chemical constituents of potato tubers (cv.Slaney). This study was laid out in a randomized complete block design with 8 treatments, three replicates were used. Obtained results could be summarized as follows: - Mineral fertilizer(NPK) treatment recorded the highest values of vegetative growth characters and yield characters follwed with mineral fertilizer (NK) and compost plus rock phosphate or PSB either alone or in combinations. The lowest values of vegetative growth parameters were recorded with application of compost alone.    Concerning chemical composition and quality parameters, the highest values of N,Pand K percentages were found in the mineral fertilizer treatments, while the lowest values of nitrate and nitrite concentration(ppm) were recorded with compost treatments either alone or in compination with rock phosphate and PSB also recorded higher values of specific gravity,starch %,T.s.s.% and ascorbic acid(mg/100g fresh weight) in both seasons.