Accepted 27th July, 2015
Despite the fact that most annual legumes (e. g. cowpea, soybean) are nitrogen fixing, their yields are still below expectation in some soils nowadays. This is not unconnected with the low/initials oil nutrient status of the sites/places of cultivation of those legumes, especially pertaining to their inability to meet the critical values required in those nutrients (pH, %N, % organic matter, available phosphorus, exchangeable bases, exchangeable acidity and effective cation exchange capacity) as result of continuous cropping/over cultivation. Thus, this study was conducted to determine the response of Glycine max (Soya bean) to four levels of NPK 15:15:15 fertilizer and four soil types for possible variations in yield. It was a 4x 4factorial experiment in completely randomized design which was replicated three (3) times. Germination / seedling emergence rates and percentages, apparent growth parameters (plant height, collar girth, number of leaves, number of branches) and yield indices (number of pods, number of seeds, weight of seeds) were assessed/ investigated. It was observed that senescence set-in /commenced at the 12th week after planting with yellowing of the leaves, browning of the pods and final cessation in growth. The study lasted for 14 weeks and loamy soil with 250kg ha-1 of NPK fertilizer had the highest mean values in growth and yield variables/parameters while the lowest mean values were recorded in sandy and clayey soils. The yield increased with increase in plant height and number of branches. Analysis of variance indicated significant differences (P< 0.05) in the growth and yield parameters. Plant height and number of branches were the two growth parameters or indices that determined the yield of this legume, these two parameters accounted for 63 – 89% of the variation in yield (R2 = 0.063 – 0.089).
Keywords: Glycine max, soil types, NPK fertilizer, growth parameters, yield