Abstract: In this paper,the current studying progresses about the effects of biochar application on agro ecosystem with respect to soil physicochemical properties,soil microbes,carbon sequestration,crop productivity,and greenhouse gases (GHGs) emission were reviewed.In summary,biochar application could improve soil fertility,soil biota habitat and nutrient use efficiency (nitrogen,phosphorus).On the other hand,there was still some uncertainty about the effects of biochar application on crop productivity (either yield or aboveground biomass).The stability of biochar played a key role in soil carbon accumulation,whereas the detailed degradation process of biochar had not been fully understood.Biochar affected the decomposition of native soil organic matter,known as the priming effect,while the priming direction (positive or negative) and magnitude varied by soil and biochar types.Considering the GHGs emission,the influence of biochar application on soil respiration and CH4 evolution had some uncertainty,whereas biochar application was proved to be effective in mitigating N2O emissions.These uncertainties mentioned above might be explained by the differences in biochar properties,application rates,soil types and fertility conditions.Thus,long term field experiments should be carried out in order to evaluate the influences and functions of biochar amendment objectively.

Key words: Biochar, Agro ecosystem, Crop productivity, Soil biota, Greenhouse gases