Quantification of Nitrous Oxide, Methane, and Carbon Dioxide Emissions from Agricultural Machinery in Tropical Lowland Rice Farming Systems

The study quantified nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) emissions from key agricultural machineries used in rice farming systems across the tropical lowland regions, particularly Cagayan Valley. Fuel consumption and machinery data were obtained from the Department of Agriculture – Regional Agricultural Engineering Division (DA-RAED). Emissions were estimated using IPCC Inventory Software (2006 Guidelines, Tier 1- 2 methodologies), with disaggregation by machinery, gas, and province. Total emissions from the agricultural machinery under study amounted to 143.66 Gg, dominated by hand tractors (130.71 Gg; 90.99%), followed by four-wheel drive tractors (8.37 Gg; 5.83%), rice combine harvesters (4.37 Gg; 3.04%), mechanical rice transplanters (0.10259 Gg; 0.07%), and precision seeders (0.09703 Gg 0.07%). At the provincial level of tropical lowland settings, Isabela and Cagayan recorded the highest emissions (77.75 Gg; 53.04% and 66.03 Gg; 45.02%, respectively), while Nueva Vizcaya and Quirino accounted for the lowest (1.80 Gg; 1.23% and 1.06 Gg; 0.72%, respectively). These findings highlight the environmental impact of mechanization in rice farming and emphasize the need for climate-smart strategies, including improved energy efficiency, adoption of low-emission technologies, and integration of renewable energy sources.