EFFECT OF ORGANIC AND MINERAL FERTILIZERS ON GROWTH AND YIELD OF COCOYAM (COLOCASIA ESCULENTA (L.) SCHOTT)

The response of cocoyam (Colocasia esuclenta (L.) Schott) to various rates of poultry manure (PM) andpotassium(K) fertilizer was studied under field conditions in 2006 and 2007 growing seasons at Uyo, a humidforest agroecology of south eastern Nigeria. Treatment combinations comprising of four rates each of PM (0, 5, 10and 15t/ha) and K (0, 40, 80 and 120 kg K/ha) were factorized and fitted into a randomized complete block designwith three replicates. Application of PM and K at the highest rates produced significantly taller plants with higherleaf area index, shoot dry matter, corms and cormels number, compared with other treatments in both years.Weight of corms and cormels and total yield (t/ha) were however, optimized at 10t/ha and 80 kg K/ha rate.Averaged over the two years, increases in PM and K rates from zero to 15t/ha and 120 kg K/ha, increased theshoot dry matter by 51% and 29%, and the number of corms and cormels by 40% and 34%, respectively. Weightof corms and cormels and total yield obtained in the two years at 10t/ha and 15t/ha PM, and 80 kg K/ha and 120kg K/ha were statistically similar except in 2007 where the corms and cormels weight peaked at 15t/ha PM rate.Poultry manure at 15t/ha in combination with either 80 kg K/ha or 120 kg K/ha out-yielded other treatments interms of corms and cormels weight and total yield in the two years of trial.