Towards site-specific nutrient management strategies: An open database in Senegal.

Building open databases is critical to creating effective, locally-informed decision support systems in agriculture. In West Africa, particularly in Senegal, the open agricultural data movement is growing but still requires further investment. This review aimed to create an open database by integrating existing data on yield response to nutrient applications for major field crops. From 5026 articles identified in the literature, only 79 were retained (482 experiments, 2992 observations). Many studies lacked treatments to assess individual nutrient effects, had limited control versus NPK comparisons, or were missing critical soil nutrient status. Over 80 % of the database consisted of crops such as rice (41 %), millet (24 %), peanut (10 %), and maize (7 %). A boundary line analysis was conducted to establish critical nutrient thresholds for maximum grain yield for nitrogen (N), phosphorus (P), and potassium (K) rates. The integration of an open soil database together with this literature data layer provided insights into the association of crop yield responses to nutrient applications and their link to the soil nutrient status. For example, rice yield response to N application showed a weak relationship with soil carbon, similar to yield without K application and soil available K, whereas yield without P application was more strongly related to soil available P. This review highlights data limitations such as incomplete field data, insufficient treatments, and difficulties in applying current data to site-specific nutrient management. Future efforts should prioritize not only decision support tools, but also high-quality local data collection with standardized protocols to support reliable decision processes.