A 13-year study on fertilization in Xihu Plain found that using chemical fertilizers with organic manure increased rice and wheat yields. Soil organic matter and total nitrogen levels also rose over time, with the highest increase seen in the manure plus chemical fertilizers treatment. Soil physical characteristics improved, benefiting water-stable granular structure and soil porosity. Nitrogen and phosphorus were in surplus with NPK plus manure and NPK plus straw treatments, while deficiencies were observed in straw and control treatments. Potassium balances were achieved with NPK plus manure and NPK plus straw, but deficiencies were found in NPK, straw, and control treatments. Overall, combining chemical fertilizers with organic manure can boost crop yields and enhance soil fertility, while increasing potassium fertilizer application can help maintain nutrient balances in the soil.