Yield and Distribution/Uptake of Nutrients of Dioscorea rotundata Influenced by NPK Fertilizer Application

Two field trials were conducted in 2005 and 2006 at Evboneka to determine the optimum level of NPK requirement for yield and nutrient composition of D. rotundata for the forest ultisol location. Fresh tuber yield, dry matter accumulation, percentage of nitrogen (N), phosphorus (P) and potassium (K) content of leaves and tubers at various stages and crude protein content of harvested tubers were evaluated under five levels (0, 100, 200, 300 and 400 kilogramme per hectare (kg ha-1) of NPK fertilizer using randomized complete block design. NPK fertilizer application significantly increased all the tested parameters. The optimum level of NPK for successful production of white guinea yam was 300 (45 kg N + 20.37 kg P + 37.35 kg K) kg ha-1 in a forest ultisol that been under cultivation for at least two years.