Assessment of the Effect of NPK Fertiliser on Pepper Yield in Oyo State

This study assesses the effect of NPK compound fertiliser application rates on the growth and fruit yield of pepper in Oyo State, South West Nigeria. Pepper is an economically important spice and vegetable crop in South West Nigeria, used extensively in Nigerian cuisine and generating significant income for smallholder farmers. Nutrient management is critical for achieving profitable pepper yields, but fertiliser recommendations for pepper in the Southwest are based on limited local data. This study establishes a randomised complete block design experiment at the Institute of Agricultural Research and Training Ibadan using four NPK 15:15:15 fertiliser rates: 0, 200, 400, and 600 kilograms per hectare applied to Tatase variety. Plant height, number of branches, number of fruits per plant, fruit weight, and total fruit yield per hectare are measured over two cropping seasons. Findings reveal that 400 kilograms per hectare of NPK 15:15:15 produces the highest fruit yield of 14.6 tonnes per hectare, representing a 148 percent yield increase above the unfertilised control. The 600 kilogram per hectare rate produces no significant further yield increase but substantially increases input cost, reducing profit margin. Foliar colour and fruit quality are improved at all fertiliser rates compared to control. The study concludes that 400 kilograms per hectare of NPK 15:15:15 is the optimal fertiliser rate for pepper production in Oyo State. It recommends this rate for inclusion in state-level extension guidance for pepper producers in South West Nigeria.

Keywords: NPK fertiliser, pepper yield, Oyo State, fruit yield, soil fertility.