Response of Maize (Zea maize) to Phosphorus Fertilizer Rates on Nitisols in Assosa Zone of Benishangul Gumuz Region, Western Ethiopia

ABSTRACT

Background and Objectives: Poor nutrient management is one of the key factors contributing to decline in the productivity of maize in Assosa. In order to investigate the effect of different phosphorus levels on the yield and yield components of maize on Nitisols in Assosa Zone during 2012-2014. Materials and Methods: The experiment was arranged in a randomized complete block design with six levels of phosphorous fertilizer (0, 23, 46, 69, 92 and 115 kg of P₂O₅ ha^-1) with three replications. Results: The results revealed substantial responses of maize to phosphorus fertilizer rates on plant height, cob height, cob length and grain yield. Grain yield increased significantly from 4724.8 to 6427.9 kg ha^-1. The magnitude of increase in grain yield due to application of P₂O₅ was 30.6% higher as compared to the control. Extractable soil P concentrations (Bray II, 0-20 cm depth) three weeks after planting significantly responded to P fertilizer rate. Conclusion: Correlations of relative yield with soil test phosphorous values showed that the critical soil P concentration and average phosphorous requirement factor (P_f) calculated from soil test phosphorous values of all treatments for the study area were 6.8 and 7.00 mg kg^-1, respectively.