Potassium fertilizer boosts summer maize yield and plant K accumulation in alluvial soil. More fertilizer means higher yield and plant K levels. The best results were seen with 150 kg·hm-2 of K2O application, leading to a 1080 kg·hm-2 yield increase and 949 yuan·hm-2 profit boost. The K plant efficiency, K utilizing plant efficiency, Potassium fertilizer efficiency, and Potassium fertilizer recovery rate decrease as fertilizer rate goes up. The optimal balance for yield, profit, and fertilizer recovery rate is achieved with 150 kg·hm-2 of K2O application.