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 (pT0 ≥ 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
Asadu et al. (2026) studied this question.