Yield Response of Local Long Maturing Sorghum Varieties to Timing of Nitrogen Fertilizer Application in Eastern Amhara Region, Ethiopia

Split-application of nitrogen fertilizer experiment was conducted in major late maturing local sorghum varieties growing areas of Eastern Amhara Region namely Sirinka and Kobo for one year (2013). The principal objective of the experiment was to identify the response of timing of nitrogen fertilizer application on grain yield of sorghum. The experiment was designed in randomized complete block consisting of five nitrogen fertilizer (69 kg/ha) application times: (1) full-dose at knee height stage, (2) 1/2 at planting + 1/2 at knee height stage, (3) 1/3 at planting + 2/3 at knee height stage, (4) 1/3 at planting + 1/3 at knee height stage + 1/3 at stem elongation and (5) 1/2 at knee height + 1/2 at stem elongation stage for late maturing local sorghum varieties (Degalit and Jamiyu) replicated three times were used in the study. Basal application of 46 kg/ha P2O5 fertilizer was made at sowing. The result revealed that split-application of nitrogen had significance difference between yield components of sorghum. From this study, the highest grain yield (6830 kg/ha) was recorded with application time of nitrogen fertilizer full-dose at knee height stage of Degalit sorghum at Sirinka. Similarly, the highest grain yield (6540 kg/ha) was recorded with application time of nitrogen fertilizer 1/2 at knee height + 1/2 at stem elongation stage of Jamiyu sorghum at Kobo. Mean combined over locations were showed also these facts. It was recommended that the best use of nitrogen fertilizer would be obtained when full-dose of the total requirement is applied at knee height stage for Degalit sorghum while 1/2 at knee height + 1/2 at stem elongation was for Jamiyu sorghum. Key words: application time, nitrogen fertilizer, growth stages of sorghu