Yield and Profitability of Sweet Potato (Ipomoea batatas (L.) Lam) as a Function of Increasing Levels of Phosphorus and Varieties in Southern Ethiopia

Sweet potato is among the most important food security crops in Ethiopia. However, its productivity is constrained by poor soil fertility and a lack of improved varieties. A field experiment was conducted to evaluate the growth and yield response and profitability of three sweet potato varieties to rates of phosphorus (P) in Southern Ethiopia. Five rates of P (0, 10, 20, 30, and 40 kg ha−1) and three sweet potato varieties (Awassa-83, Kulfo, and Local) were considered as treatments that were laid out in a randomized complete block design with three replications. The vine length, internodes length, diameter, and the number of vines were significantly varied among varieties while P had a nonsignificant effect on these parameters. The tuber yield of sweet potato was influenced by the combined effect of variety and P rate. The highest marketable yield (30.22 t ha−1) was obtained at 30 kg P ha−1 from variety Awassa-83 and the lowest marketable yield (6.57 t ha−1) was obtained from Kulfo at 0 kg P ha−1. Thus, improvement of sweet potato productivity in the study area could be achieved through the use of Awassa-83 variety with P at a rate of 10 kg ha−1.