The study looked at how applying phosphorus fertilizer affects soil phosphorus levels and crop yield in a wheat-rice crop rotation. They found that increasing phosphorus fertilizer rates led to higher soil phosphorus levels and increased grain yield in rice. The residual effects of phosphorus on wheat were also significant, maintaining higher yields. For optimal results, applying 135 kg·hm-2 of phosphorus for wheat and 90 kg·hm-2 for rice was recommended. Decreasing phosphorus application to 45 kg·hm-2 in rice season maintained high yields for both rice and wheat. Overall, applying phosphorus fertilizer during the rice season was found to be beneficial for crop growth in North China.