Timing and Rate of Nitrogen Application Influence Profitability of Maize Planted at Low and High Densities in Northwest Pakistan

Abstract

Getting maximum benefits from maize (Zea mays L.) lies not in reducing N rate and its number of splits but in lowering cost per unit production through higher yields. Field experiments were conducted on maize at the New Developmental Research Farm of North West Frontier Province (NWFP) Agricultural University Peshawar during summer 2002 (Y1) and 2003 (Y2) to investigate the effects of variable rates of N and its time of application on the net returns (NR) of maize (cultivar Azam) planted at low and high densities. The 2 × 3 × 6 factorial experiment was designed having two plant densities (D1 = 60,000 and D2 = 100,000 plants ha−1) and three N levels (N1 = 60, N2 = 120 and N3 = 180 kg N ha−1) as main plots, and six split N applications: two equal (S1), three unequal (S2), three equal (S3), four equal (S4), five equal (S5) and five unequal splits (S6) applied at sowing and with first, second, third, and fourth irrigation at 2 wk intervals as subplots. Maize planted at high density gave about 18% higher NR than at low density, and the increase in NR was comparatively more (3%) in the second growing season than the first growing season. Net returns showed positive relationship with increase in N rates, and increased by 19,565 and 31,948 PKR ha−1 with 120 and 180 kg N ha−1, respectively as compared with 60 kg N ha−1 The increase in NR with N3 was 39% greater than N2. Among the N timings, S5 showed the highest NR (16,646 PKR ha−1) and was 3, 21, and 97% greater than S6, S4, and S3,, respectively. The NR from S2 was negative (−783 PKR) when compared with S1 (control). In conclusion, the findings suggests that growing maize at high density applied with 180 kg N ha−1 in five equal or unequal splits could be more economical in terms of NR in the study area.