Researchers studied the effects of different fertilization and irrigation methods on wheat and maize yields in North China. They found that using the right combination of nitrogen and phosphorus fertilizers, along with appropriate irrigation, is crucial for improving crop yield. Nitrogen and phosphorus had the most significant impact on crop yield, while potassium and irrigation had less effect. Increasing nitrogen and irrigation rates led to higher nitrate nitrogen levels in the soil, increasing the risk of leaching. To reduce this risk, it is important to use the right amount of nitrogen and phosphorus fertilizers, with an irrigation rate of less than 280 mm per year for wheat and maize crops in this region.