Effects of biochar application on soil nitrogen transformation and N 2 O emissions: a review

Abstract

The sustainability and uncertainty of global climate warming have a profound impact on the sustainable development of human society. The continuous increase of atmospheric N2O concentration is one of the major contributions to the global climate warming. Soil is an important site of nitrogen transformation and a biochemical reaction reservoir of the nitrogen cycle, and also an important source of N2O emissions. Therefore, changes in soil N2O emission rate will significantly affect atmospheric N2O concentration. Biochar refers to the aromatic chemicals prepared by pyrolysis of biomass under the condition of complete or partial hypoxia. Biochar has the characteristics of porosity, strong adsorption, chemical stability, high pH and large cation exchange capacity. After it is applied to soils, biochar will directly or indirectly affect the transformation process of soil nitrogen and significantly affect the soil N2O emissions. This article reviewed the research progress of biochar effects on nitrogen transformation and N2O emission in the soil ecosystem, elaborated the effects of biochar input on the dynamic changes of soil inorganic nitrogen, nitrification, denitrification and N2O emission. Futher, in terms of biochar’s absorption and reduction of nitrogen leaching, effects on soil physicochemical properties, abundance and diversity of soil ammonia oxidizing bacterial, along with functional genes of denitrifying bacteria, the machamnisms influencing the processes above-mentioned are specifically elucidated in details. The future research of biochar in increasing soil sinks, reducing emissions and mitigating the greenhouse effect, as well as the related technology promotion, have been prospected. [Ch, 109 ref.]