Carbon Footprint of Rice Production System.

Managing carbon (C) footprint under anaerobic rice cultivation conditions is an important issue concerning climate change and sustainable food production. Modern rice cultivation technologies (e.g., machinery, fertilizer, pesticide, irrigation etc.) involve high use of fossil fuel based energy. These inputs have high C cost of 1,419 kg CE ha-1. The average rice yield of 4,259 kg ha-1 and co-product of 9,463 kg ha-1 are equivalent to 1,533 kg CE ha-1 and 3,366 kg CE ha-1, respectively. The total C footprint for flooded rice paddy fields is 1,980 kg CE ha-1. Emission of other greenhouse gas (GHG) is estimated at 179 kg of CH4 and 4.9 kg of N2O ha-1 of rice paddy, while the losses of C by erosion in rice paddies are negligible. Aerobic rice may save water use and extend cultivation into drier regions. Mid-season drainage also reduces CH4 emission. Yield reduction of 10% by aerobic culture may save water use by 25-35%, and reduce CH4 emission by 90%. However, aerobic rice may increase N2O emission from N fertilization in aerated soils. Research implies that appropriate management may reduce carbon footprint of rice production.