Long-term use of NPK fertilizers in rice fields increases grain yield, nutrient uptake, and soil fertility. Nitrogen works best with phosphorus, while potassium benefits from both nitrogen and phosphorus. Regular nitrogen application lowers soil pH but maintains available nitrogen. Phosphorus application boosts available phosphorus by three times over 36 years. Potassium application also increases available potassium significantly. Balanced NPK fertilizer application is crucial for high yields and long-term soil health in rice cultivation.