Silicate (Si) fertilizers are well-known for soil amendment and to improve rice productivity as well as nitrogen efficiency. In this study, we investigated to reduce the application level of nitrogen for rice cultivation by applying Si fertilizer. Field experiments were carried out to evaluate the productivity of rice (Oryza sativa) on a silt loam soil, where three levels of nitrogen (0, 110 and 165 kg ha-1) were selected and Si fertilizer as a slag type was applied at 0, 1 and 2 times of the recommended level (available SiO2 130 mg kg-1). The Si fertilizer increased significantly rice yield and nitrogen efficiency. Rates of 1 and 2 times of the recommended Si fertilization decreased the nitrogen application level to about 76 and 102 kg N ha-1 to produce the target yield, i.e., the maximum yield in the non Si amended treatment. Silicate fertilizer improved soil pH and significantly increased available phosphate and Si contents. Conclusively, Si fertilizer could be a good alternative source for soil amendment, restoring the soil nutrient balance and reducing the nitrogen application level in rice cultivation.