EFFECT OF SPLIT APPLICATION OF NPK FERTILIZER ON GROWTH, YIELD AND NUTRIENT USE EFFICIENCY RESPONSES OF THREE GINGER CULTIVARS IN THE RAINFOREST ECOLOGY OF NIGERIA

The effect of split application of NPK fertilizer on the growth, yield and nutrient use efficiency responses and the economic profitability of ginger production using split NPK fertilization practice on the low fertility rainforest ecology soils of South Eastern Nigeria was assessed in a two year (2012/2013) field study conducted at the research farm of the National Root Crops Research Institute, Umudike, Abia State, Nigeria. Treatments comprised three ginger cultivars (Maran, Wynad Local and Himachel Pradesh) factorially combined with eight inorganic fertilization methods designated M1 to M8 as: Full dose of optimum NPK fertilizer rate applied once after planting (M1); ½ dose of optimum rate applied after planting and ½ dose applied 4 WAP (M2); Full dose of optimum rate applied at once during land preparation + 10 kg N/ha of urea applied 12 WAP (M3); Full dose of optimum rate applied at once 4 WAP (M4); ½ dose of optimum rate applied after planting, ½ dose applied 4 WAP + 10 kg N/ha applied 12 WAP (M5); 1/3 dose of optimum fertilizer rate applied after planting, 1/3 applied 2 MAP and another 1/3 applied 4 MAP (M6); Full dose of optimum rate applied at once during land preparation (M7); and 1/3 dose of optimum rate applied in three split doses (after planting, 2 MAP, and 4 MAP) + 10 kg N/ha of urea applied 12 WAP (M8)}. Full dose of optimum NPK fertilizer rate applied once by broadcasting after planting constituted the first control while a plot containing no NPK fertilizer treatment (Absolute control) constituted the second control in the study. Compared to the traditional single basal pre-plant fertilization, split fertilizer application and/or delayed basal application generally resulted in the production of taller ginger plants, higher fresh rhizome yield and a higher N, P and K nutrient use efficiency in addition to higher return per Naira investment. Maran gave higher height, rhizome yield and nutrient N, P and K use efficiency than Wynad Local and Himachel Pradesh. The implication of this result is that split fertilizer application is an important strategy for a successful nutrient management program in ginger production in the fragile soils of south eastern Nigeria.