Source and rate of nitrogen application influence agronomic N-use efficiency and harvest index in maize (Zea mays L) genotypes


The objective of this research work was to compare the agronomic N use efficiency (NUEA) and harvest index re¬sponse of different maize (Zea mays L) genotypes to different N-fertilizer sources [urea, calcium ammonium nitrate (CAN) and ammonium sulphate (AS)] at various levels (0, 50, 100, 150, and 200 kg ha-1). Field experiments were conducted at the Agriculture Research Farm of The University of Agriculture, Peshawar, Pakistan during summer 2008 (year one) and 2010 (year two). The two years data indicated that NUEA had negative relationship with in¬crease in N rate (50 > 100 > 150 > 200 kg ha-1) while harvest index had positive relationship with increase in N rate up to 150 kg ha-1 (200 < 150 > 100 > 50 kg ha-1). Both NUEA and harvest index ranked first with application of AS (AS > CAN > urea). The maize hybrid produced higher NUEA and harvest index than local cultivars (Pioneer-3025 > Jalal > Azam). Although AS had the highest NUEA and harvest was still considered the less profitable N-fertilizer source because of its highest N cost kg-1 [AS (143 and 191 PKR kg N-1) > CAN (77 and 97 PKR kg N-1) > urea (44 and 56 PKR kg N-1)] in 2008 and 2010, respectively. The decline in AS price could make it more profitable and most beneficial N-fertilizer source in the calcareous soils of the country because of its free available sulfur (24%) lacking in urea and CAN.


Zea mays L; genotypes; N levels; N source; agronomic N use efficiency; harvest index

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