Effects of tied-ridge, nitrogen fertilizer and cultivar on the yield and nitrogen use efficiency of sorghum in semi-arid Ethiopia

Moisture deficit, poor soil fertility and lack of improved varieties constrained sorghum production in north-eastern Ethiopia. An experiment was conducted in 2002 at Kobo and Sirinka in north-eastern Ethiopia to study the possible effects of seedbed, nitrogen fertilizer and cultivar on the yield and N use efficiency (NUE) of sorghum. The experiment was carried out in a split-split plot design with seedbed (tied-ridge vs. flatbed planting) as main plots, N fertilizer (0, 40 and 80 kg N ha(-1)) as subplots and sorghum cultivars (Jigurti, ICSV111 and 76T1#23) as sub-sub plots, with three replications. At Kobo, the seedbed by cultivar interaction affected all parameters. Nitrogen fertilization increased biomass yield and NUE at both locations and grain yield at Sirinka. Cultivars showed different performance where ICSV111 and 76T1#23 were superior in grain yield, N uptake and concentration, N harvest index and NUE of grain (NUEg) compared with Jigurti. Thus, planting ICSV111 and 76T1#23 in tied-ridging and with N fertilization at Kobo and in flatbed and with N fertilization at Sirinka is recommended. This study revealed that tied-ridging is not a solution in all areas where moisture deficiency is a problem. Its effectiveness is affected by rainfall amount and soil type.