Yield and Profitability Analysis of Orange Flesh Sweet Potato (Ipomoea batatas (L.) Lam.) Varieties at Different Rates of Blended NPSB Fertilizers at Central Ethiopia

Abstract

Sweet potato (Ipomoea batatas (L.) Lam) is one of the economically important and food securing root crop in Ethiopia. Fertilizer has a greater effect on the yield of sweet potato crop. A field experiment was conducted at Qebena Woreda, Rekaboka kebele to evaluate the effect of four different rates of NPSB fertilizers (0, 75, 150, and 225) kg/ha on the yield of the three orange fleshed Sweet potatoes varieties (OFSP) (Kebode, Alamora and Dilla). The experiment was arranged in 3 x 4 factorial randomized complete block design with three replications. The analysis of variance revealed that the interaction effect of the varieties and NPSB rates were highly significantly influenced the vine number, internode length, shoot fresh and dry weight, and total tuber number per plant. However, a number of leaf per plant, shoot fresh weight, shoot dry weight, total tuber number per plant, root fresh weight, and root dry weight were resulted significantly the highest difference due to the main both effect of both variety and fertilizer (P < 0.01). Statistically, the highest number of leaf per plant was obtained from Dilla combined with 225 and 150 kg/ha (659.72 and 632.22), respectively. The Dilla variety with 225 kg/ha resulted significantly highest difference in both shot fresh and shoot dry weight (1526.10 and 6466.67 kg). Kebode with 150 kg/ha resulted significantly highest difference in root fresh and dry weight (22762 kg) and (20524.7 kg), respectively. The Kebode, which received 150 kg/ha of NPSB scored the highest marketable tuber number (5.00) and the least unmarketable tuber number (1.22). Significantly, highest different total tuber number was scored in the Dilla with no NPSB fertilizers application (8.22). Root fresh weight was significantly the highest different in Kebode, which received 150 kg/ha (22762 kg), and followed by the kebode variety with 225 kg/ha. The Root dry weight was significantly the highest in the Kebode × 150 kg/ha (20524.7 kg), 225 kg/ha NPSB (17978.4 kg), respectively. The Total tuber yield was significantly the highest in the Kebode with 150 kg/ha (20.52 tonha). The analyzed partial budget for the average of the whole treatments was resulted in the highest MRR at the Kebode, Dilla, and Alamora, which received 150 kg/ha with 238.57%, 125.29%, and 144.49%, respectively. The highest marginal rate of return 238.57% was obtained in Kebode with150 kg/ha. The Overall 150 kg/ha NPSB was recommended with the Kebode in terms of yield per hectare for the highest significant yield. However, further studies should be needed for the remaining OFSP varieties for yield improvement with respect to the different rates of NPSB fertilizer.