Abstract: Biochar is a charcoal produced under high temperatures using crop residues, animal manure, or any type of organic material. Biochar has multiple potential environmental benefits, foremost the potential to sequester carbon in soil for hundreds to thousands of years, which consequently can slow down the greenhouse effect so as to restrict global warming. Crop yields can increase as a result of applying biochar as a soil amendment. Moreover, greenhouse gas emissions are reduced significantly with biochar application to crop fields. However, obstacles exist that may stall rapid adoption of biochar production systems, including technology costs, feedstock availability, and the uncertainty of longterm effect of biochar application. Some characteristics of biochar depend on the biomass source and temperature, duration and method of pyrolysis. The effects of biochar on soil physical, chemical, microbial properties and emissions of greenhouse gases (such as carbon dioxide, methane and nitrous oxide) were reviewed. We also summarized the effects of biochar on rice production and greenhouse gas emissions in southern China and other foreign areas, and the characteristics of charcoal produced in forest fire and its environmental effects.

Key words: nitrification-denitrification, nitrous oxide (N₂O), restoration wetland, exogenous nitrogen, Yellow River estuary.