Nitrogen and Phosphorus Fertilizers and Tillage Effects on Growth and Yield of Maize (Zea mays L.) at Dugda District in the Central Rift Valley of Ethiopia

An experiment was conducted at Dugda district in the Central Rift Valley of Ethiopia under field conditions to determine the impacts of tillage levels, N and P fertilizers on growth and yield of maize (Zea mays L.). Two tillage levels; (1) Conventional and (2) Minimum tillage and four N and P fertilizer levels; (1) No fertilizer (control treatment), (2) 64 kg N haG1 (139 kg urea haG1 ), (3) 20 kg P haG1 (100 kg TSP haG1 ) and (4) 64 kg N haG1 +20 kg P haG1 (100 kg DAP haG1 + 100 kg urea haG1 ) were laid out in split plot design by assigning tillage levels to the main plots and fertilizers to the subplots and replicating three times. Data collected on growth and yield parameters was analyzed using the GLM procedure of SAS Version 9.2. N and P fertilizers had highly significant effects on growth parameters: plant height and leaf area. They also significantly affected yield parameters: biomass yield and grain yield of maize but the effects of tillage levels as well as the interaction between tillage levels and fertilizers were not significant. For the majority of the growth and yield parameters, the treatment with 64 kg N haG1 +20 kg P haG1 (100 kg DAP haG1 + 100 kg urea haG1 ) outperformed the remaining three treatments. Accordingly, significant and highest plant height (178.24 cm), leaf area (431 cm2 ), biomass yield (11925 kg haG1 ) and grain yield (3678.8 kg haG1 ) were obtained from the application of fertilizer treatment with 64 kg N haG1 + 20 kg P haG1 (100 kg DAP haG1 +100 kg urea haG1 ). The results of the correlation analysis also indicated that biomass yield was significantly and positively correlated with grain yield and grain yield was also significantly and positively correlated with harvest index. This indicated that N and P fertilizer treatments with higher biomass yield and harvest index could result in higher grain yield of maize. According to the current results, it can be concluded that N and P fertilizers significantly affected the growth and yield of maize but tillage levels have no significant effect. Therefore, the use of 64 kg N haG1 +20 kg P haG1 (100 kg DAP haG1 +100 kg urea haG1 ) and minimum tillage could be recommended for optimum growth and yield of maize and also save the precious soil, money and time of resource poor small holder farmers, of the study area.