Spatial Distribution of Nutrient Loads Based on Mineral Fertilizers Applied to Crops: Case Study of the Lobo Basin in Côte d’Ivoire (West Africa)

Eutrophication in the Lobo watershed remains a major problem. The work carried out has focused on chemical and biological analyses lake or its immediate environment: they did not sufficiently take into account diffuse transfer of nutrients over entire watershed. This study aims to assess nutrient (N P) loads watershed, an agricultural area, understand spatio-temporal impacts land management practices eutrophication. methodology uses two steps: streamflow calibration estimation using Soil Water Assessment Tool (SWAT) model. Thus, inputs were estimated based levels N P every kilogram Nitrogen-phosphorus-Potassium (NPK) type fertilizers applied by farmers. average quantities crops 47.24 kg ha−1 21.25 ha−1. Results show good performance flow as evidenced evaluation criteria R2, Nash–Sutcliffe Efficiency (NSE), Percent Bias (PBIAS) 0.63, 0.62, −8.1, respectively. yields inorganic soluble varied from 0 0.049 0.31 These results that crops’ nitrogen requirements higher than demands for phosphorus. Simulations relating organic revealed values ranging 0.2 5 ha−1, while transport phosphorus was vary 0.3 1.3