Response surface methodology to determine the optimum yield of white yam at different levels of NPK fertilizer application

Abstract

Fertilizers are essential to modern agriculture, their overuse can have harmful effects on human being, plants, crops and soil quality (Popoola, O. P et .al,2015)[6].Thus, this research work attempts to develop a multiple regression model to investigate the effect of three levels of NPK fertilizer on the yield of white yam, examine if the trio of Nitrogen, Phosphorus and Potassium (NPK) contribute to the growth and yield of white yam; also, to detect which of the three elements of NPK contribute most. It does further to determine at what proportion each of the three elements is to be applied for optimum yield and if applied correctly, confirm the optimum yield at kilogram per hectare. A3x3 factorial design ANOVA was adopted in the data analysis to determine if the fertilizers used have effect on the white yam. Post Hoc analysis was carried out using LSD, Tukey, Scheffe and Bonferroni test to determine which level of the fertilizers differed, multiple regression analysis was used to investigate at what proportion the elements are to be applied for optimum yield. Also, Response Surface Methodology was carried out to obtain the optimum yield of white yam, the results of the analysis showed that the trio of Nitrogen, Phosphorus and Potassium (NPK) contribute to the growth and yield of white yam for both main effect and interaction effects at thedifferent levels ofapplication. Furthermore, the overall Multiple Regression models for the Yield of white yam was obtained at Y = 319.0834 + 7.0717N - 26.7399P + 32.6546K – 1.9665NP – 2.5493NK – 0. 6896PK.Thus, the nitrate and potash combination produced the best yields on the average of 390.3118 tone/kilogram per hectare when used at N₇₅ k.g and K₆₀k.g_.