Aims: A field experiment was conducted to investigate the effect of biochar on maize yield and greenhouse gases (GHGs) in a calcareous loamy soil poor in organic carbon from Henan, central great plain, China. Methods: Biochar was applied at rates of 0, 20 and 40 t ha with or without N fertilization. With N fertilization, urea was applied at 300 kg N ha, of which 60% was applied as basal fertilizer and 40% as supplementary fertilizer during crop growth. Soil emissions of CO, CH and NO were monitored using closed chambers at 7 days intervals throughout the whole maize growing season (WMGS). Results: Biochar amendments significantly increased maize production but decreased GHGs. Maize yield was increased by 15.8% and 7.3% without N fertilization, and by 8.8% and 12.1% with N fertilization under biochar amendment at 20 t ha and 40 t ha, respectively. Total NO emission was decreased by 10.7% and by 41.8% under biochar amendment at 20 t ha and 40 t ha compared to no biochar amendment with N fertilization. The high rate of biochar (40 t ha) increased the total CO emission by 12% without N fertilization. Overall, biochar amendments of 20 t ha and 40 t ha decreased the total global warming potential (GWP) of CH and NO by 9.8% and by 41.5% without N fertilization, and by 23.8% and 47.6% with N fertilization, respectively. Biochar amendments also decreased soil bulk density and increased soil total N contents but had no effect on soil mineral N. Conclusions: These results suggest that application of biochar to calcareous and infertile dry croplands poor in soil organic carbon will enhance crop productivity and reduce GHGs emissions. [ABSTRACT FROM AUTHOR]