Effects of soil amendments on the nutritional quality of okra (Abelmoschus esculentus [L.]Moench)

Abstract

This study examined the effects of different soil amendments [compost organic fertiliser (OR), NPK (IO), Glomus mosseae mycorrhiza (MY) or no soil amendment as the control (CT)] on the nutritional quality and nutrient uptake of okra during cultivation in a field contaminated with sewage sludge from the two oxidation ponds of the Obafemi Awolowo University, Ile-Ife, Nigeria. Okra (Abelmoschus esculentus [L.] Moench) belongs to the Malvacea family. The experiment consisted of a randomised complete block design with four replications. At full physiological maturity, the roots, shoots and pods samples of the okra plants were collected for analyses. The results showed that OR resulted in a significantly (p < 0.05) higher nutrient uptake [N (0.0034 mg kg -1 ), K (0.0160 mg kg -1 ), Na (0.9753 mg kg -1 ), Ca (0.0130 mg kg -1 ) and Cu (0.01136 mg kg -1 )] in the okra roots than in the other treatments, yet the significantly (p < 0.05) highest uptake of P (0.0012 mg kg -1 ) was obtained with the MY treatment. Lower values of these nutrient contents were obtained in the shoots. The control treatment gave the significantly highest values of crude fibre (27.33%) and total ash (14.05%), as compared to the other treatments, whereas the other nutritional properties obtained showed no significant difference among any of the treatments. The results indicated that high-quality okra pods could be effectively produced with no soil amendment when planted in soils with a high fertility, such as those treated with sewage sludge.