EFFECT OF FOUR NPK FERTILIZER FORMULATIONS AND THEIR APPLICATION RATES ON GROWTH AND YIELD OF MAIZE (Zea mays L.) IN THE GUINEA SAVANNAH AGROECOLOGY OF GHANA

Abstract

Most farmers in the Northern Region of Ghana are unaware of other NPK formulations such as NPK 20-10-10, 20-20-20, 17-17-17, 23-10-10 and 23-10-5 but the most commonly used one is NPK 15-15-15. Pot and field experiments were set-up at the University for Development Studies (UDS) in the Guinea Savanna Zone of Ghana from January to April (Dry season) and June to October (Rainy season) respectively, to study the growth and yield response of maize to the application of NPK fertilizer formulations. In both pot (Experiment I) and field (Experiment II) studies, 4 x 4 factorial experiments were laid out in Randomized Complete Block Design (RCBD) with four replications. The sixteen treatments were made up of four NPK formulations; 15-15-15, 23-10-5, 23-10-10 and 20-10- 10, each applied at four rates; 0, 350, 375 and 400 kg/ha where 0 kg/ha was the control. Vegetative growth and yield parameters of maize were measured in both experiments. With all the parameters, application at 375 and 400 kg NPK/ha recorded the best performance in respect to the fertilizer formulations, and at all instances did not differ significantly from each other. Grain yield highly correlated positively with chlorophyll content, leaf area, stem girth, cob length, cob weight, stover weight, number of seeds per cob and thousand seed weight. Result for cost benefit analysis revealed that all control plots recorded losses, whiles all treated plots recorded profits. The application at 375 kg/ha maximised the most profit in all fertilizer formulations, except for NPK 23-10-10, where maximum return was achieved by application at 400 kg/ha. Among various formulations, NPK 15-15-15 recorded the highest average return, followed by 23-10-5, 20-10-10 and 23-10-10. The study recommends that irrespective of NPK fertilizer formulation, application at 375 kg/ha is recommended in maize production for maximum grain yield and profit; but for application at 350 kg/ha, 23-10-10 NPK is recommended for optimum yield and profit. Also based on accessibility and affordability, NPK ISIS-IS is highly recommended among the various formulations.