Biochar Addition Balanced Methane Emissions and Rice Growth by Enhancing the Quality of Paddy Soil

Paddy rice production may contribute to both the global issues of methane emissions and food security. Biochar derived from organic wastes may offer a potential solution to address these two challenges. The current study aimed to examine the dynamics of methane emissions, rice growth, and soil quality as affected by biochar and to assess the biochar role in balancing methane emissions and rice growth in paddy soil. Paddy soil was mixed with rice-husk-derived biochar at five levels (0, 1.5, 3, 6, and 12% w/w) and planted with rice (Oryza sativa L.) in two consecutive seasons in a greenhouse. Methane emissions from experimental pots were measured weekly. After each of the two seasons, the crop’s root, stem, and grain mass were determined, and soil samples were collected and analyzed for 10 physicochemical properties, which were used to compute the soil quality index (SQI). Compared to the no-biochar treatment, biochar increased total rice biomass from 8 to 48% while suppressing methane missions from 7 to 42%, dependent on biochar rates and seasons. Biochar with different rates also enhanced SQI by 10 to 45% and 38 to 101% after the first and second seasons, respectively. A strong relationship was observed between methane emissions and total rice biomass with SQI suggesting that soil quality may play a major role in suppressing CH4 emissions and enhancing rice growth. Adding biochar to paddy soil can reduce methane emissions while improving rice growth, which is strongly linked to the enhanced quality of the biochar-added soil.