ABSTRACT Ammonia volatilisation causes major nitrogen losses from the soil and applied urea which results in low urea-N usage efficiency. Incubation experiment and pot experiment were conducted to assess the effect of enriched rice straw biochar on ammonia volatilisation, soil pH, exchangeable ammonium, available nitrate, and rice plant growth in comparison to the urea without additives under waterlogged conditions. During the incubation study, urea was amended with different rates of enriched rice straw biochar (5, 10, 15, and 20 t ·ha-1). Urea amended with biochar at 5 to 10 t·ha-1 had successfully minimized ammonia loss compared to urea without biochar. Besides, application rate of 5 to 10 t·ha-1 of biochar also preserved more ammonium ions (65.37% and 66.54%, respectively), while at the same time, the retention of nitrate ions was 50.9% and 45.3% over urea without biochar. Similarly, 5 to 10 t·ha-1 of enriched rice straw biochar increased soil N level and improved rice plant growth significantly in pot experiment. Precisely, incorporation of enriched rice straw biochar at rate of 5 and 10 t·ha-1 offers wide variety benefits to soil amendments and rice plant nutrient uptake. Hence, the findings suggest that urea amended with enriched rice straw biochar altered the nutrients level in soil by improving rice plant growth.