Abstract: A five-year successive rice straw-derived biochar (BC) amendment pot trial was conducted to investigate the BC effects on crop growth responses, soil properties and ammonia volatilization in a calcareous alkaline soil from 2010-2015 under the greenhouse condition. We adopted 0 (the control; BC₀), 2.25 t·hm^-2(BC_2.25) and 22.5 t·hm^-2(BC_22.5) for each wheat/millet crop season with an identical dose of NPK fertilizers. The results showed that BC treatments (BC_2.25 and BC_22.5) improved soil fertility and crop growth compared to the no BC control. During the five rice/millet rotations, BC_22.5 treatment increased the total yields of grain and straw by 24.1% and 74.1%, while the cumulative aboveground uptake amounts of N, P and K were significantly increased by 93.5%, 71.2% and 46.3%, respectively. After the rotations, soil available P, K, and CEC under the BC_22.5 treatment were enhanced by 262%, 274% and 58.3%, compared to the control. By contrast, soil bulk density was decreased by 46.6%, while no difference was found in soil pH between the BC treatments and the control. Soil TOC and soil C/N ratio increased by 843% and up to 25 in response to the BC_22.5 treatment, respectively. The annual apparent BC loss was 3.5%-5.7% in the BC_2.25 and BC_22.5 treatments. High level of BC application simulated ammonia volatilization, which increased by 102% in BC_22.5 treatment over the course of the crop rotations compared to the control.