Impact of Combined Mineral Fertilizer Application Methods (NPK and Urea) on Okra (Abelmoschus esculentus L.) Cultivation in Zatta, Ivory Coast

Abstract

Background : Information on the response of the ‘Teriman’ variety of okra (Abelmoschus esculentus L.) to combined mineral fertilisation under the field conditions of Zatta, Côte d’Ivoire, is limited. Aims : The objectives of this study were to optimise okra (Abelmoschus esculentus L., ‘Teriman’ variety) production through combined mineral fertilisation and to evaluate the comparative effects of NPK (15-15-15) and urea (46%) on vegetative growth and yield components. Study Design : The experimental protocol was based on a completely randomised Fisher’s block design comprising four treatments repeated three times over an area of 153.6 m² : T0 (control without fertiliser), T1 (NPK : 200 kg/ha), T2 (Urea: 50 kg/ha), and T3 (NPK + Urea combination). Place and Duration of Study : The experiment was conducted in the town of Zatta, located in the Yamoussoukro Autonomous District (Ivory Coast), during the agricultural season leading up to harvest, which began on April 15, 2026. Methodology : A randomised block experiment comprising four treatments and three replicates was established over 153.6 m². The treatments were an unfertilised control (T0), NPK at 200 kg/ha (T1), urea at 50 kg/ha (T2) and combined NPK and urea (T3). Plant height, collar diameter, leaf number, fruit number, fruit weight and yield were evaluated. Data were assessed using analysis of variance or the Kruskal–Wallis test at a 5% significance level. Results : The results indicate that treatment T3 (NPK + urea) significantly increased the number of leaves (an average of approximately 33 leaves compared with approximately 29–30 leaves under the other treatments) (p = 0.016). However, with regard to yield, significant differences were observed (p = 0.001) : Treatment T1 (NPK alone) had the highest yield, at 139.13 g/m², followed by the control T0 (128.93 g/m²), whereas the T3 combination had the lowest yield (82.07 g/m²). Conclusion : The study concludes that an excess of nitrogen (T3) stimulates vegetative growth at the expense of fruit set. The application of NPK (T1) had the highest observed yield and was therefore the most effective method in this experiment for improving okra productivity in the Zatta region.