Comparative evaluation of different organic fertilizers on the soil fertility, leaf minerals composition and growth performance of dikanut seedlings (Irvingia gabonnesis L.)

An experiment was carried out at Akure in the rainforest zone of Nigeria to determine the effectiveness, of ten organic fertilizers on plant growth, soil fertility, and leaf nutrients composition of dikanut seedlings in the nursery.The organic fertilizer treatments were applied at 8t/ha (40g/10kg soil) to each polybag, a reference treatment NPK 15-15-15 compound fertilizer applied at 2g NPK/10kg soil (400kg/ha) and a control treatment (no chemical fertilizer nor manure), arranged in a completely randomized design (CRD) and replicated four times.The results showed that the organic fertilizers increased the seedlings' growth significantly (P<0.05),leaf and soil N, P, K, Ca, Mg, soil pH and O.M of dikanut compared to the control treatment.The oil palm bunch ash + poultry manure increased the plant height, leaf area, stem girth, leaf numbers and root length of dikanut seedlings by 22%, 50%, 33%, 21% and 49% respectively, when compared to the NPK chemical fertilizer treatment.It also increased the leaf N, P, K, Ca and Mg of dikanut seedlings by 35%, 37%, 39%, 36% and 65.3% respectively compared to the sole application of poultry manure.Oil palm bunch ash + poultry manure treatment increased the soil pH, O.M, N. P, K, Ca, Mg by 6%, 13%, 19%, 28%, 32%, 33% and 21% respectively compared to the cocoa husk + spent grain treatment.Therefore the, oil palm bunch ash + poultry manure applied at 8t/ha was the most effective treatment in increasing growth, soil and leaf parameters of dikanut seedlings.