Effects of Organic and Inorganic Manures Combined With Lime on Soil Properties and Sweet Potato (Ipomeabatatas) Performance in a Ultisol at Nsukka, Eastern Nigeria

The effects of selected manures and agricultural lime on soil properties and sweet potato performance were evaluated twice during the 2023 cropping season in an ultisol at the Department of Soil Science farm, Nsukka, Nigeria. The five treatments considered were T0 (control), T1 (poultry manure only) applied at a rate of 5.56 t/ha, T2 (lime + NPK 20:10:10), lime at a rate of 1.67 t/ha, and NPK at a rate of 8.3 t/ha, T3 (lime + NPK 20:10:10 + poultry manure) at a rate of 7.22 t/ha, and T4 (NPK 20:10:10 + poultry manure) applied at a rate of 6.39 t/ha. The treatments were laid out in a RCBD replicated four times. Soil and crop data were collected following standard procedures. The soil physicochemical properties were not significantly influenced by the treatments, except for the improved aggregate stability. The chemical properties remained in the low fertility status, but the soil pH remained in a suitable range for most crops at harvest. At one month after planting (MAP), the mean number of leaves (NOL) produced by T2 plots was the highest and significantly (p<0.05) higher than those from T4 and T1 plots but similar to those from T3 and T0 plots. Again, T3 plots produced the longest mean vine length, which was significantly higher than those from T4, T0, and T1 plots but similar to that from T2 plots. At MAPs of 2.3 and 4, the differences in these growth parameters among the plots were not significant. At harvest, the plots that received only poultry manure (T1) had the highest mean fresh weight of tubers (35.8 t/ha), which was significantly higher than that from the control (8.33 t/ha) but similar to those from the other plots. The statistical order of the effects of treatment on tuber yield was T1>T0 ≥ T4 ≥ T2 ≥ T3. This trend was the same for the residual trial. Thus, for an ultisol under Nsukka environment, the use of poultry manures alone at 5.56 t/hawas recommended for the production of sweet potato