Paddy rice is a staple crop for much of the world’s population. It is also a key source of the greenhouse gas methane, responsible for about 40 million tonnes, or 10% of global emissions, each year.
Sustainable rice production practices that reduce water consumption and the need for fertilizers can control increasing methane emissions and ensure the livelihoods of millions of smallhold rice farmers.
The Coalition supports countries and farmers to overcome the challenges of adopting sustainable rice production practices with the aim of reducing methane emissions, while maintaining, and often even improving, rice yields.
Rice is grown in warm, waterlogged soil. Farmers traditionally flood rice paddies throughout the growing season - a practice known as continuous flooding - providing ideal conditions for microbes that produce large amounts of methane.
Simple changes to farming practices can significantly decrease these methane emissions, while also reducing the amount of water consumed during the growing season.
Alternate wetting and drying (AWD), the practice of allowing the water table to drop below the soil surface at one or multiple points during a growing season, is an effective alternative to continuous flooding, proven to reduce methane emissions by as much as 48%. The practice is also cost-saving for farmers, as it requires a third less water than continuous flooding and does not compromise yield.
AWD entails the periodic draining of a field to a certain threshold, usually 15 cm below the soil surface, before re-flooding. A perforated tube placed in the soil enables the farmer to monitor the water level below the soil surface to determine when to irrigate. During dry phases, the methane-producing bacteria are inhibited.
Efficient nitrogen use and application of organic inputs to dry soil can further reduce methane emissions.
The Coalition aims to promote AWD practices on a large scale.
To achieve this objective, the Coalition supports activities that identify priority areas for AWD implementation and provide incentives, technical support mechanisms and enabling conditions to help farmers overcome barriers to new practices.
The Coalition is currently carrying out activities in Vietnam, Bangladesh, and Colombia. Specific interventions include:
- Supporting and informing governments in the implementation of AWD policy
- Providing technical assistance to existing loan programs to enable scaling up of AWD
- Developing a business case for AWD implementation in countries
- Mobilising action with the dissemination of AWD information
- Developing and implementing a tool for impact analysis of AWD programs
Widespread efforts to implement AWD practices would achieve benefits for the climate, ecosystems, and rice farmers.
- Reduced water use: By reducing the number of irrigation events required, AWD can reduce water use by up to 30%. It can help farmers cope with water scarcity and increase reliability of downstream irrigation water supply.
- Greenhouse gas mitigation potential: AWD is assumed to reduce methane emissions by an average of 48% compared to continuous flooding. Combining AWD with nitrogen-use efficiency and management of organic inputs can further reduce greenhouse gas emissions. This suite of practices can be referred to as AWD+.
- Increased net return for farmers: AWD does not reduce yields compared to continuous flooding, and may in fact increase yields by promoting more effective tillering and stronger root growth of rice plants. Farmers who use pump irrigation can save money on irrigation costs and see a higher net return from using AWD. AWD may reduce labour costs by improving field conditions (soil stability) at harvest, allowing for mechanical harvesting.
- CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS)
- International Rice Research Institute (IRRI)
- Institute for Agricultural Environment (IAE) in Vietnam
- Bangladesh Agricultural University (BAU)
- International Center for Tropical Agriculture (CIAT)
- National federation of rice farmer (Fedearroz) in Colombia