Effect of Poultry Manure and NPK Fertilizer Soil Amendments on Some Agro-Morphological Parameters, Protein and Mineral Nutrient Contents in Cocoyam (<i>Xanthosoma </i><i>sagitifolium</i> L. Schott)

The main objective of our study was to evaluate the effects of poultry manure (PM) and NPK (20:10:10) fertilizers on some agro-morphological parameters, protein and mineral contents in the leaves and tubers of white and red cv cocoyam (Xanthosoma sagittifolium L. Schott) plants. Results revealed that the poultry manure (25 and 30 t∙ha−1) and NPK fertilizer (125 and 150 kg∙ha−1) treatments positively influenced growth, development and tuber yield in both white and red cv X. sagittifolium plants. The carbon-to-nitrogen (C/N ratio) in the poultry manure treatments (30 t/ha) most significantly influenced crude protein content (18.14%) in red cv X. sagittifolium tubers. Soil analysis revealed that the cation exchange capacities (CECs) were more significant in poultry manure treatments, thereby enhancing mineral uptake. Mineral content analysis in harvested tubers showed that calcium (Ca), magnesium (Mg), sodium (Na), phosphorus (P), iron (Fe), zinc (Zn), and manganese (Mn) were more significant in red cv X. sagittifolium tubers than in the white cv X. sagittifolium tuber for all treatments. The white cv X. sagittifolium tubers recorded a more significant potassium (K) content than the red cv X. sagittifolium tubers for all treatments. These results suggest that red cultivar X. sagittifolium tubers could be used as an important dietary mineral source. Principal component analysis (PCA) results confirmed high positive correlations between soil exchangeable cations (Mg2+ and Na+) and average leaf number for both cultivars. PCA results also illustrated that soil exchangeable K+ was highly correlated to yield parameters (average tuber girth, length and weight).