Effect of Nitrogen Fertiliser Rates on the Growth and Yield of Maize in Benue State

This study examines the effect of different nitrogen fertiliser application rates on the growth and grain yield of maize in Benue State, North Central Nigeria. Nitrogen is the most limiting nutrient for maize production in Nigerian savanna soils, and optimising its application rate is critical for achieving high yields while minimising cost and environmental impact. Despite the importance of maize as a food security crop in Benue State, farmer fertiliser use is often either inadequate or based on blanket recommendations that do not reflect local soil conditions. This study establishes a randomised complete block design field experiment at the University of Agriculture Makurdi research farm, applying five nitrogen rates: 0, 40, 80, 120, and 160 kilograms per hectare as urea. Plant height, leaf area index, ear length, grain weight per cob, and grain yield are measured at critical growth stages. Findings reveal that grain yield increases significantly up to 120 kilograms of nitrogen per hectare, achieving an average yield of 5.8 tonnes per hectare, beyond which the response plateaus and grain quality declines. The 120 kilogram rate also generates the highest agronomic efficiency and benefit-cost ratio. The study concludes that 120 kilograms of nitrogen per hectare represents the economically optimal rate for maize production in Benue State conditions. It recommends adoption of this rate as the standard fertiliser recommendation for maize in the state and farmer training on split application to maximise nitrogen use efficiency.

Keywords: nitrogen fertiliser, maize yield, Benue State, agronomic efficiency, fertiliser recommendation.