Abstract
Nitrogen is one of the most important factors affecting maize yield and profitability. To investigate the impact of N fertilizer sources (urea, calcium ammonium nitrate [CAN] and ammonium sulfate [AS]) applied in various amounts (0, 50, 100, 150, and 200 kg N ha(-1)) on grain yield and profitability of maize genotypes, local cultivars (Azam and Jalal) versus hybrid (Pioneer-3025) field experiments were done during summer 2008-09 (Year 1) and 2009-10 (Year 2). The N yielded 41 and 26% more grain than the check in Year 1 and Year 2, respectively. In both years, grain yield increased in response to the increase in N application. Application of CAN and AS resulted in more grain yield than urea in Year 1, while no differences in yield were observed in Year 2. The hybrid (P-3025) yielded 30 and 24% more grain than the average of local cultivars in Years 1 and 2, respectively. In Year 1, the net returns (NR) of PKR16262 ha(-1) (one US$ = 95 Pakistani Rupees) was obtained with CAN but value cost ratio (VCR) of 3.7 was noticed with urea; in Year 2, both NR (PKR14271 ha(-1)) and VCR (3.1) was greatest with urea. In both years, the greatest NR was obtained with 100 and 150 kg N ha(-1). Application of urea at 150 and 200 kg N ha(-1), CAN at 100 and 150 kg N ha(-1), and AS at 50 and 100 kg N ha(-1) was economical in terms of NR in both years.