Understanding Lowland Rice Farmers’ Knowledge of Soil Fertilization Practices and Perceptions of Nitrogen-Induced Water Pollution Risks in the Ouémé Watershed, Central Benin

In Benin’s lowland rice fields, water resources are vulnerable to nitrogen pollution due to shallow water tables, nutrient runoff, and inappropriate fertilization practices. This study assessed rice farmers’ soil fertilization practices and their perceptions of water pollution risks. Data from 176 farmers were analyzed using descriptive statistics, logit, and tree regression. The results revealed that farmers applied an average of 79.4 ± 1.55 kg N ha−1 (53 kg N ha−1 from urea (46% N) and 26.4 kg N ha−1 from NPK), exceeding the recommended rate of 60 kg N ha−1. This excess was due to the overapplication of urea by 75% of farmers, who applied it at an average rate of 115.2 ± 2.59 kg ha−1 instead of the recommended 75 kg ha−1. Only 16% adopted pro-environmental practices. Farmers trained in water pollution risks and familiar with fertilizer policies were 36 times more likely to adopt sustainable practices. Downstream farmers applied less urea and were eight times more likely to adopt such practices. Farmers with over 10 years of experience were 17 times more likely to understand the watershed network. Despite 60.8% reporting eutrophication and 72.2% noticing water quality decline, only 34.1% linked nitrogen use and water pollution. Tree regression analysis indicated that 78% of untrained farmers were unaware of the environmental impacts of poor fertilization. These findings underscore the need to integrate specific concepts on nutrient management and water resource pollution into training programs and policies for lowland rice farmers in Benin, while also improving the knowledge transfer mechanism.