Two field experiments were conducted at Sids Agricultural Research Station Farm during 2010 and 2011 seasons to investigate the effect of two nitrogen fertilizer sources, namely ammonia gas (83% N) and urea (46.5% N) with three levels, i.e. 60, 90 and 120 kg N/fed as well as rock phosphate as phosphorus source under two levels (0.0 and 300 kg rock P/fed) on growth characters ,yield and its components,net income and N, P and K concentrations and uptake of maize (Zea mays L.) as well as soil fertility. The results show that 120 kg N/fed as ammonia gas recorded the highest values of plant height, dry weight/plant, ear length and diameter, 100-seed weight, grain and stover yields, net income, N, P and K concentrations and uptake and nitrogen availability, while number of rows and kernels/ear and P and K availability not affected by either nitrogen sources or levels. Application of rock phosphate significantly increased plant height, dry weight/plant, 100-seed weight, grain and stover yields, net income, N and P concentrations and N, P and K uptake as well as P availability, while ear length and diameter, number of rows and kernels, K concentration and the availability of N and K in soil after harvesting not affected. Phosphorus concentrations in both grains or stover and N and P availability in soil after harvesting were affected by increasing nitrogen levels only under ammonia gas application.