The study was conducted to determine the effect of NPSB fertilizer rates and inter row spacing on tuber yield and yield components of potato.The treatments consisted of four levels of NPSB (50,100,150 and 200 kg ha-1) fertilizer and three inter row spacing (65, 75 and 85cm) with control treatment. The results of combined analysis of variance showed that the main effect of NPSB application rates and inter row spacing were significantly affected Plant height, Number of main stem, Number of tuber, Marketable tuber, total tuber yield and average tuber weight. Hence, application of 200 kg ha -1 NPSB resulted maximum marketable tuber yield (51.36 t ha-1). Marketable tuber yield was strongly correlated with tuber number (r=0.49**), total tuber yield (r=0.99***) and average tuber weight (r=0.92***). Besides, the the highest net benefit obtained (1231355 birr ha-1) with acceptable marginal rate of return (3823.92%) and (2120240 birr ha-1) with acceptable marginal rate of return (11444.83%) from NPSB kg ha-1 and 85cm inter row spacing respectively. Therefore, the production of potato with 150 kg ha -1NPSB fertilizer rate and 85 cm inter row spacing is most productive and economically profitable and can be recommended for the study area for further scaling up.

Keywords: Potato, NPSB, Inter row spacing