Accurate nitrogen (N) fertilization and optimum plant density increases crop yields. In this study I report the effects of N fertilization rate and plant density on maize yield a meta-analysis, by using observations from 15 studies conducted in Ethiopia since the 2000s for possible refinement of N fertilizer and plant density recommendations. I assessed the response of maize to: different N rates ha?1 compared to the control using the yield response approach. Application of N fertilizer significantly increased maize yields by 31.5% - 65.9% compared to control. Plant density increased maize yields by 42%-72.4% compared to the control. The interaction effect of N rate increased maize yields by 27.6% - 95.9%, with Plant density, 58.7% - 152% on loam soil, compared to control yield. The interaction effect of Plant density with soil type increased maize yields by 47% - 108% on loam soil. In conclusion, the grain yield of maize increased with increasing N rate and plant density up to the optimum. Therefore, it’s possible to recommend using high N rate with both low and medium plant density (<45,000 plants ha-1) and (45,000 to 65,000plants ha-1) to harvest high grain yield.

Keywords: Zea mays; yield response; Nitrogen rate; plant density.