Effect of Urea Fertilizer and Maize Cob Ash on Soil Chemical Properties, Growth, Yield, and Mineral Composition of Okra, <i>Abelmoschus esculentus</i> (L.) MOENCH

Abstract

Abstract Field experiments were carried out at the Teaching and Research Farm, Landmark University, Omu-Aran, Kwara State, Nigeria, in the cropping seasons of 2015 and 2016. The soil at the site of the experiment is an Alfisol classified as an Oxichaplustalf or a Luvisol. The trial consisted of sole and combined applications of urea fertilizer (U) applied at 0, 60, and 120 kg·ha −1 and maize cob ash (M) applied at 0, 3, and 6 t·ha −1 . The results showed that U and M alone or in combinations increased the soil chemical properties, growth, yield, and mineral composition of okra compared with the control. M alone at 3 t·ha −1 produced optimum soil chemical properties, yield, and mineral composition of okra fruit. U alone at 60 kg·ha −1 produced optimum yield of okra, while growth and mineral composition were increased when urea fertilizer was applied at 120 kg·ha −1 . The treatment with U applied at 60 kg·ha −1 in combination with M applied at 3 t·ha −1 (U 60 M 3 ) produced the highest values of okra yield, while U applied at 120 kg·ha −1 in combination with M applied at 3 t·ha −1 (U 120 M 3 ) has the highest growth and highest N, K, Ca, Cu, and Fe contents of okra fruit. Compared with the control and using the mean of the two years, U 60 M 3 increased okra fruit yield by 93.3%. Therefore, for viable production of okra in low nutrient soil of the Nigeria derived savanna or similar soils elsewhere, 60 kg·ha −1 U + 3 t·ha −1 M (U 60 M 3 ) is recommended. However, for improved mineral quality of okra, 120 kg·ha −1 U + 3 t·ha −1 M (U 120 M 3 ) is recommended.