Sorghum grain yield under different rates of mineral and organic fertilizer application in the South-Sudan zone of Burkina Faso

Abstract

Soil fertility depletion has been recognized as the most important limitation to food security in Burkina Faso. Crop production eg sorghum is constrained by inadequate supply of fertilizers and there is therefore the need to establish optimum fertilizer rates for increased and sustainable yields. This study is a short-term experiment conducted during the 2014 cropping season on a Luvisol in the sub-sudanian zone of Burkina Faso. The experiment was laid out in a split plot, arranged in a randomized complete block design with three replications. Cattle manure (CM) at two rates (0 t ha-1 and 5 t ha-1) constituted the main plot whilst mineral fertilizer (kg ha-1) at eleven rates (0N-0P-0K, 40N-0P-0K, 60N-0P-0K, 40N15P-0K, 60N-15P-0K, 60N-7.5P-0K, 60N-22.5P-0K, 60N-15P-10K, 60N-15P- 20K, 60N-15P-30K and 90N-15P-20K-15S-2.5Zn-10Mg-0.5B) constituted the sub-plots. The highest grain yield response was observed under sole application of 60 kg N ha-1 and 22.5 kg P ha-1. However, the yield obtained under these treatments was not significantly different from the grain yield observed under the applications of 40 kg N ha-1 and 15 kg P ha-1. Since lower N and P rates gave similar grain yield as the reference plot (90N-15P-20K-15S-2.5Zn-10Mg-0.5B), sole application of 60 kg N ha-1 and 22.5 kg P ha-1 can be considered as appropriate rate for optimum grain yield production. The interaction effect of cattle manure and mineral fertilizer did not significantly (P > 0.05) increase sorghum grain yield. The highest grain yield obtained in this case, was with the interaction between 5 t of cattle manure ha-1, 60 kg N ha-1 and 7.5 kg P ha-1 mineral fertilizer rates applied. No significant difference (P > 0.05) in sorghum grain yield was obtained above this fertilizer rate which can undoubtedly be suggested as the optimum rate. The Value Cost Ratio (VCR) of 2.01 and 2.23 obtained respectively under 60N-22.5P-0K and the interaction of cattle manure with 60N-7.5P-0K at the beginning of the wet season slightly exceeded the critical value of 2 required to motivate farmers to apply mineral fertilizer. Thus, fertilizer requirement for sustainable sorghum grain production at the study area in Burkina Faso is 5 t ha-1 of cattle manure combined with 60 kg N ha-1 and 7.5 kg P ha-1.