Effects and rates of broiler and layer manures on the leaf yield and tissue nutrient contents of moringa (Moringa oleifera Lam.) in Swaziland

Abstract

Moringa (Moringa oleifera Lam) has been gaining increasing attention in Swaziland as a medicinal plant increasingly being exploited due to its medicinal value especially amongst people living with HIV/AIDS. The tree is being cultivated in most homesteads and fertilized using poultry manure. A pot experiment was conducted in the greenhouse during the 2016/2017 cropping season. The aim was to investigate the effects two sources of manure (i.e. broiler and layer) at five rates (0, 15, 30, 45 and 60 tonnes/ha) on dry matter yield (i.e. leaves, petioles, stems and roots) and tissue nutrient contents of moringa. The experimental design was a randomized complete block design (RCBD) in a factorial arrangement with four replicates. Data collected (i.e. number of leaves/plant, dry matter of leaflets, stems, roots and tissue nutrients- Fe, Mn, Zn, Cu and Cd) were analyzed using Statistical Analysis Software. Results showed that the application of broiler and layer manures at different rates had no significant effect (p > 0.05) on the number of leaves/plant. The dry matter yields were significantly different considering the sources and rates of manure applications. Furthermore, results showed that the tissue nutrient contents of micronutrients (i.e. Fe, Mn, Zn and Cu) and Cd were generally higher than the maximum permissible limits (MPL) of the World Health Organization as well as daily dietary intake for medicinal plants. Evidence from this study suggest that moringa can successfully be grown using poultry manures however, the application of the aforementioned manures was found to result in elevated contents of micronutrients and cadmium in plant tissue which may be harmful for human consumption.