Abstract:
Tef is a highly valued crop in the national diet of Ethiopians and the major crops grown in Southern Ethiopia. However, its productivity is constrained by low plant-available soil nutrients due to depleting soil organic matter content and long history of intensive cultivation. Therefore, a field experiment was carried out Tambaro district during the 2019 main cropping season with the objective of:to assess the combined responses of N and blended NPSB fertilizer rates on growth, yield and yield components of tef. To determine economically optimum N and blended NPSB fertilizer, application rate for high grain yield of tef. The experiment consisted four levels of nitrogen (0,23,46 and 69 kg N ha-1) and four levels of blended (0, 50, 100 and 150 kg NPSB ha-1) in factorial combinations using quench tef variety as a test crop. The experiment was laid out in RCBD with three replications. The result revealed that the main responses of N rates were highly Significant (P<0.01) in terms of total number of tillers,90% physiological maturity, 50%panicle emergence and productive tillers. Grain yield, straw yield, harvest index and aboveground dry biomass are significant(P<0.05) on main responses of N rates. The highest values were recorded at the highest rate of 69 kg N ha-1. Similarly, the main responses of blended fertilizer were significant(P<0.01) on plant highest, 1000 kernel weight and 90% physiological maturity. The combined application of N and blended fertilizer are not significant on plant physiological maturity, biomass, grain yield, plant highest, panicle length, total tiller and effective tillers. The highest plant height, effective tillers, panicle length and total tiller where obtained at highest application rate of (69 kg N ha-1), While the lowest were obtained from-unfertilized (control) plot. On the other hand, the highest straw yield (7038.5kgha-1) and biomass (7326.56kgha-1) where obtained from the highest application rate of 23/150 N/NPSB and 69 N are respectively. While the lowest straw yield (5126.88kgha-1) and biomass (6059.2kgha-1) where obtained from control plot. The maximum yield (2533.3kg ha-1) was obtained from at combined application of 46kg N and100 kg NPSB (ha-1) fertilizers rate. Applying 100 kg blended NPSB (ha-1) Supplemented with 46kg N (ha-1) had the highest net benefit, relatively low variable cost together with highest and acceptable MRR for tef production in Tambaro district
