Methanotrophic Inoculation Reduces Methane Emissions from Rice Cultivation Supplied with Pig-Livestock Biogas Digestive Effluent

• Published in: Agronomy (Basel) Vol. 14; no. 6; p. 1140
• Main Authors: Thao, Huynh Van, Tarao, Mitsunori, Takada, Hideshige, Nishizawa, Tomoyasu, Nam, Tran Sy, Cong, Nguyen Van, Xuan, Do Thi
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2024
• Subjects: Agricultural production; Agrochemicals; Air pollution; Bacteria; Biogas; biogas digestive effluent; Biomass; Biomass energy; Carbon; Carbon sources; Cattle; Climate change; Climatic changes; Copy number; Crop production; Cultivation; Effluents; Emissions; Eutrophication; Feasibility studies; Fertilizers; Floods; Grain cultivation; greenhouse gas; Greenhouse gases; Inoculation; Livestock; Methane; Methanogenic archaea; Methanotrophic bacteria; methanotrophs; Nitrification; Nitrogen; Nitrous oxide; Organic carbon; Organic fertilizers; paddy fields; Productivity; Rice; Rice fields; Substrates; Japan; Vietnam
• ISSN: 2073-4395; 2073-4395
• DOI: 10.3390/agronomy14061140

Biogas digestive effluent (BDE) is a nutrient-enriched source that can be utilized as an organic fertilizer for rice cultivation without synthetic fertilizer (SF) application. However, a primary concern is the stimulation of methane (CH4) emissions due to the enrichment of the labile organic carbon, a favorite substrate of methanogenic archaea. Methanotrophs potentially reduce greenhouse gas (GHG) emissions from rice fields owing to metabolizing CH4 as a carbon source and energy. We therefore examined the effect of the application of methanotroph-inoculated BDE to the rice cultivated paddy soil on GHG emissions and rice productivity under a pot experiment. Methanotrophs (Methylosinus sp. and Methylocystis sp.), isolated from the Vietnamese Mekong Delta’s rice fields, were separately inoculated to the heated BDE, followed by a 5-day preincubation. Methanotroph-inoculated BDE was supplied to rice cultivation to substitute SF at 50% or 100% in terms of nitrogen amount. The results showed that the total CH4 emissions increased ~34% with the application of BDE. CH4 emissions were significantly reduced by ~17–21% and ~28–44% under the application of methanotroph-inoculated BDE at 100% and 50%, respectively. The reduction in CH4 was commensurate with the augmentation of pmoA transcript copy number under methanotroph-inoculated BDE. In addition, methanotroph-inoculated BDE application did not increase nitrous oxide (N2O) emissions and adversely affect rice growth and grain productivity. This study highlighted the BDE-recirculated feasibility for a lower CH4 emission rice production based on methanotrophs where high CH4-emitting fields were confirmed.