Optimization of N, P and K Fertilization for Orange-Fleshed Sweet Potato (Ipomoea batatas (L) Lam) Production at Ikwo Abakaliki, Southeast Nigeria

Orange-fleshed Sweet potato (Ipomoea batatas (L) Lam) is one of the most important crops for human consumption and livestock feed. All parts of the plant are useful for human consumption, animal feed and industrial uses. This research was conducted on a degraded Ultisol at the Teaching and Research Farm, Faculty of Agriculture, Alex Ekwueme Federal University, Ndufu-Alike (AEFUNAI), Abakaliki Ebonyi state during 2022 and 2023 planting seasons, to determine the optimum rate of N, P and K Fertilization for Orange-Fleshed Sweet Potato (Ipomoea batatas (L) Lam) Production at Ikwo Abakaliki, Southeast Nigeria. The treatments comprised of Nitrogen fertilizer (Urea with 46% N) applied at four levels namely 0, 45, 90, and 135 kg N/ha; Phosphorus fertilizer (Triple Super Phosphate with 20% P) applied at four levels namely 0, 15, 30, and 45kg P2O5/ha and Potassium fertilizer (Muriate of Potash with 50% K) applied at four levels namely 0, 20, 40, and 60 kg K2O/ha. The treatments were combined to give 64 treatment combinations with three (3) replicates. The experiment was factorial experiment laid out in a Randomized Complete Block Design (RCBD). Data were collected on vine length (cm), number of leaves, number of branches, weight of storage root/plot (kg/plot) and total storage root yield (t/ha) and subjected to ANOVA for factorial experiment in RCBD at 5% probability level. The results showed that the various combined rates of NPK fertilizer significantly (P < 0.05) increased all the growth and yield parameters of orange-fleshed sweet potato compared to the control during two years of experiment. Also, the results of 2023 planting season were better than that of 2022 planting season. However, the application of NPK at the rate of 90kgN-45kgP2O5-60kgK2O recorded the highest number of OFSP leaves (374.3 and 388.0), number of OFSP branches (19 and 20.33), vine length of OFSP (457.0cm and 444.7cm), weight of OFSP storage root (3.070kg/plot) and (3.5kg/plot) and total storage root yield (3.255t/ha) and (3.88t/ha) in 2022 and 2023 respectively. NPK fertilizer application at the rate of 90kgN-45kgP2O5-60kgK2O appeared appropriate for optimum yield for orange-fleshed sweet potato production in the study area and is therefore recommended.