INFLUENCE OF DIFFERENT SOURCES AND LEVELS OF NITROGEN AND ROCK PHOSPHATE ADDITION ON MAIZE PRODUCTIVITY AND SOIL FERTILITY

Abstract

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.