Growth and Yield Response of Sweet Potato (Ipomoea batatas) to Organic and Inorganic Fertilizer on Degraded Soil of Southern Guinea Savanna of Nigeria

The problem of soil fertility makes it difficult for some crops to attain higher yields; especially crops like sweet potato that our traditional peasant farmers believed that it does not require the application of fertilizer. Therefore, experiments were conducted during the rainy season of 2018 and 2019 titled “Growth and Yield Response of Sweet Potato (Ipomoea batatas) to Organic and Inorganic Fertilizer on Degraded Soil of Southern Guinea Savanna of Nigeria” to determine the optimal levels of both organic and inorganic fertilizer for sustainable sweet potato production. The treatments consisted of three levels of NPK fertilizer (0, 50 and 100 kg ha-1); three rates of poultry manure (0, 5 and 10 t ha-1). A factorial experiment laid in a Randomized Complete Block Design (RCBD) and replicated three times. The result showed NPK fertilizer applied at the rate of 100kg ha-1 produced the highest number of leaves/plant (178, 233); number of branches/plant (10.45, 11.98); and vine length/plant (245.43cm, 258.79cm) in both 2018 and 2019 cropping season respectively. Also, poultry manure at 10t ha-1 produced the highest number of leaves/pant (221, 242); number of branches/plant (11.24, 13.25); and vine length (252.45cm, 275.54cm) in both years of cropping respectively. Application of 100kg ha-1 of NPK fertilizer produced the highest tuber weight of 21.12 and 22.72t ha-1, in both 2018 and 2019 cropping seasons respectively compared with the other rates of fertilizer application and the control. Also, Poultry manure at the rate of 10 t ha-1 produced the highest total weight of 21.32 and 24.19t ha-1 of sweet potato in both 2018 and 2019 cropping seasons respectively compared with the other rate of fertilizer application. Interaction between NPK fertilizer and poultry manure show a significant (p<0.05) increased on the total tuber weight in both years (2018 and 2019). For integrated nutrient management in sweet potato production 50kg ha-1 of NPK fertilizer and 10t ha-1 of poultry manure produced the best total tuber weight.