Application of Blended (NPSB) and Urea Fertilizers Levels for Wheat Production across Soil Types and Agro-Ecologies of SouthEastern Ethiopia

For three cropping seasons, field experiment was carried out on different farm lands at Gedeb-Hasasa and Lemu-Bilbilo districts of Arsi zone of Oromia, South-eastern Ethiopia, to determine optimum NPSB and urea fertilizers rates for selected crop, soil and climatic conditions by varying levels of NPSB fertilizer (0, 100, 150, 200, 250 kg ha-1), urea (0, 150, 250, 350 kg ha-1) and recommended NP in combined RCBD with three replications on yield and yield components. The soil analysis result of experimental sites at post harvest indicated that, the application of treatments significantly (p < 0.01) affected pH, total N organic matter and available P for samples taken from experimental sites of wheat crop. Application of different fertilizer levels had significant effects on post-harvest pH and organic carbon contents. In a similar way, the application of treatments significantly (p < 0.01) affected total N organic carbon and available P for samples taken from experimental sites of wheat crop. Soil pH of wheat field was significantly (p < 0.05) affected by different fertilizer treatments. Different fertilizer treatments had significant effects on post harvest soil organic carbon content at Lemu-Bilbilo district. Combined levels of NPSB and urea fertilizers rates were significantly affected grain and above ground biomass yields at Gedeb-Hasasa and Lemu-Bilbilo districts. Agronomic maximum grain and above ground biomass yields (6170 and 13510 kg ha-1) in 2017 and minimum (4038 and 10908 kg ha-1) in 2018 cropping season were obtained, respectively, up on the application of NPSB and urea fertilizers, and significant grain and above ground biomass yield (6440 and 14846 kg ha-1) were obtained from the application of 250 + 350 kg ha-1 NPSB + urea rates, respectively, at Gedeb-Hasasa district. The highest grain and above ground biomass yields (6584 and 12709 kg ha-1) in 2019 and lowest (5229 and 10674 kg ha-1) in 2018 cropping season were obtained, respectively, up on the application of NPSB and urea fertilizers rate, and significant grain and above ground biomass yield (6629 and 13372 kg ha-1) were obtained from the application of 250 and 350 kg ha-1 NPSB and urea at Lemu-Bilbilo district.