Variable-rate fertilization based on yield maps is a precision agriculture approach that improves nutrient management and crop performance. Platforms like the John Deere Operations Center automatically collect yield data from combines, enabling detailed post-harvest analysis of agronomic practices. Yield maps help identify low-yield zones that may signal nutrient deficiencies and allow fertilizer rates to be adjusted according to actual yield potential. These maps can be cross-referenced with satellite imagery (e.g., NDVI), soil test results, and crop type data to refine fertilization strategies. They also support evaluation of how in-season fertilization decisions affect yield across different field zones and varieties. This data-driven method enables farmers to develop targeted, cost-effective fertilization plans for the next season, reduce input waste, and enhance overall productivity and sustainability.