Recent advances in using biochar application for greenhouse gas mitigation strategies in rice field

Abstract

Rice cultivation is very important to global food security. However, it is one of the main causes of powerful greenhouse gases (GHGs), especially methane (CH4) and nitrous oxide (N2O). These gases are a major reason why the global climate is changing. Biochar, a charcoal-like substance produced by pyrolysing biomass, offers a promising way to sequester these emissions in rice paddies. The potential of biochar as a green alternative for reducing GHGs emissions in rice fields remains largely unclear. This review summarises recent advances in using biochar to reduce GHGs emissions. This study demonstrates that using biochar in rice fields can reduce CH4 emissions by 15–26%, N2O emissions by 10–55%, and the total net global warming potential (GWP) by 5–38%. Similary, it increases rice yield by 6–14%. Biochar also suppresses N2O emissions by enhancing N retention, absorbing NH4+/NO3−, stimulating complete denitrification (through enriching N2O reductases (nosZ) -harbouring bacteria) and modulating pH. The efficiency of these processes depends on factors such as dosage (10–40 t ha−1), pyrolysis temperature (above 500 °C), substrate type, soil type and water management practices (e.g. alternate wetting and drying (AWD)). This study provides crucial information for the reduction of GHGs worldwide.