Comparative effects of organic, mineral and organo-mineral fertilizers on the yield and nutritional quality of orange-fleshed sweet potatoes in urban and rural areas of Côte d'Ivoire

The low fertility of soils in Côte d'Ivoire is a major constraint on the productivity and nutritional quality of orange-fleshed sweet potatoes (OFSP). This study evaluated the comparative effect of organic fertilization (OF), mineral NPK fertilization (MF), and organo-mineral fertilization (OMF) on tuber yield and nutritional quality in two agroecological zones, Abidjan (urban) and Tiangakaha (rural), using a completely randomized block design. The results indicate a significant improvement in yield and nutritional density under all fertilizer treatments compared to the control (p < 0.05), with FOM consistently performing better. The maximum yield (8.36 t/ha) was recorded in Tiangakaha under FOM. This fertilization also led to a significant increase in protein (2.04 %), dietary fiber (6.25 %), and β-carotene (10.4 mg/100 g DM in Abidjan; 9.7 mg/100 g DM in Tiangakaha), compared to the control (7.1 mg/100 g DM). Essential minerals were significantly enriched, particularly potassium (up to 512 mg/100 g DM), magnesium (41 mg/100 g DM) and iron (0.88 mg/100 g DM), while mineral fertilization promoted calcium accumulation (52 mg/100 g DM). Conversely, carbohydrates and starch were found in higher concentrations in unfertilized plots. These results demonstrate that the integration of organic and mineral amendments is an effective agronomic biofortification strategy, simultaneously optimizing the yield and nutritional density of OFSPs. The adoption of fertilization practices adapted to local soil conditions is therefore a sustainable lever for strengthening food security and contributing to the reduction of micronutrient deficiencies in Côte d'Ivoire.