Liming and N fertilization are common practices for optimizing crop yields in tropical agriculture, but the adequate N rate to ensure crop development, enhance yields and N use efficiency, and improve soil chemical properties has not been established for grass rotation. We assessed the optimal N fertilizer rate for combination with liming in an agricultural system composed of two grasses (maize and rice) in rotation under no-till (NT) conditions. Four N rates (0, 50, 100, and 150 kg N·ha⁻¹) were tested under two liming conditions. Maize (11 Mg·ha⁻¹) and rice (5 Mg·ha⁻¹) yields were highest with lime and 150 kg N·ha⁻¹ applications. At 18 months after liming, lime application increased soil pH. In addition, combining liming with N fertilization further increased SOM content at all N rates. Lime increased available P, exchangeable Ca²⁺ and Mg²⁺, and BS at N rates of 0, 50, and 100 kg N·ha⁻¹. Overall, combining liming and N fertilization is beneficial for grass crops under NT conditions, as evidenced by enhanced maize and rice N use efficiency and yields. N fertilization rates of 100 and 150 kg N·ha⁻¹ under lime amendment provided the best improvements in crop yields in this cropping system.