Effect of different nitrogen fertilizer rates on wheat yield under the arid and semi-arid climatic conditions of Nangarhar province

Nitrogen is one of the essential and primary elements among plant nutrients and it is mainly around 30% accessible to plants as applied. Nitrogen is losing around 70% from the soil due to multiple factors. Therefore, the excessive nitrogen fertilizer application rate can cause soil, air, and underground water pollution and increasing temperature and can create different disorders. Thus, an experiment was conducted to find a suitable nitrogen fertilizer rate to improve the production of PBW-154 wheat variety under arid and semi-arid climatic conditions. The experiment consisted of seven different nitrogen rates, T1 0, T2 80, T3 100, T4 120, T5 160, and T7 180 kg ha-1. Nitrogen was split 25% at germination and initial vegetative growth stage, while the remaining 50% was applied at tillering and flowering stages. Data was collected for vegetative (plant height, number of leaves, number of tillers) and reproductive (length of spike, number of grains per spike, 1000 grains weight, yield kg/ha) growth parameters accordingly. The results revealed that significantly (P < 0.05) higher values of vegetative growth and reproductive growth parameters, including production weight, were observed in the T6 treatment compared to other treatments. Additionally, the T6 treatment exhibited the highest yield (39.2 gr weight of 1000 grains and 4.47 tons/ha of grains weight). It increased by 41 % suitable nitrogen fertilizer application rate under the arid and semi-arid climatic conditions. The suitable nitrogen rate for arid and semi-arid climatic conditions is 160 kg ha-1 compared to 180 kg ha-1 and above. It could reduce the extra expenses of the farmers, protect the air, soil, and water from pollution, and increase the benefit-cost ratio of field cultivation for the reference crop.