Main Article Content
Potato is the most important vegetable crop next to Khat in eastern Ethiopia. However, its production is low mainly due to low inherent soil fertility and poor soil fertility management practices. Thus, field experiments were conducted to assess the effect of inorganic NPS fertilizer and farmyard manure on growth, tuber yield and quality of potato in eastern Ethiopia in 2018/19. Six rates of NPS fertilizer (0,100, 150, 200, 250 and 300 kg ha-1) and three rates of FYM (0, 5 and 10 t ha-1) in factorial combinations were evaluated in randomized complete block design with three replications. The results revealed that total number of tubers per hill, marketable and total tuber yields were significantly influenced by the interaction of blended NPS × farmyard manure and location. The combined application of 150 kg NPS with 5 t FYM and 200 kg with 10 t FYM ha-1 produced the highest total number of tubers per hill, marketable (28.1; 22.0 t ha-1) and total tuber yields (35.7; 27.0 t ha-1) at Haramaya and Hirna, respectively. Higher dry matter content (24.8%), specific gravity (1.099 g cm-3) and tuber starch content (17.54%) were recorded at 5 t FYM ha-1 application at Hirna. Partial budget analysis also affirmed that the combined application of 150 kg NPS with 5 t FYM and 200 kg with 10 t FYM ha-1 gave higher net benefit with higher marginal rate of return at Haramaya and Hirna, respectively. Therefore, it is concluded that the combined application of 150 kg NPS ha-1 with 5 t FYM and 200 kg NPS ha-1 with 10 t FYM ha-1 to Bubu potato variety are agronomically optimum and economically feasible fertilizer rates to get higher potato tuber yield at Haramaya and Hirna, respectively. Further, it is recommended to conduct onfarm demonstration trials to verify the results under farmers’ field conditions to release technology.