Water Management

Background

Methane is a highly potent greenhouse gas contributing to global climate change.  There are many sources of methane emission, including rice field cultivation, livestock, and burning of biomass.  Global emissions from rice fields alone are probably in the range of 30-80 Teragrams of methane per year.¹  As the largest worldwide producer of rice, China leads the world in methane gas emissions from rice fields.  Without any significant changes, methane emissions from rice fields will continue, and will be a significant source of GHG emissions contributing to global climate change in the futu

How it works

By changing water management actions, emissions can be reduced in irrigate rice production.  These changes include midseason drainage of the rice paddies, as well as intermittent irrigation.  These practices can reduce methane emissions by 40%.  Other practices of water management in rice production include shallow flooding, which has the added benefit of reducing the amount of water needed for rice growth.² However, the Agenda for Negotiation in Copenhagen notes that while water saving techniques can reduce GHG emissions in a particular piece of cultivated land, the saved water is subsequently used for more irrigation in future seasons, and the previous savings  in emissions are offset by further emissions in newly cultivated fields.³

Examples of implementation

India:  With one midseason drainage of the rice paddies in india, revenue dropped by less than 5%.  However, "GHG emissions drop by almost 75 million mt of CO2."⁴

Phillippines:  Alternate Wetting and Drying reduced methane emissions by "almost 50 percent as compared to rice produced under continuous flooding."  This approach had the added benefit of increasing the amount of income earned by poor farmers, while simultaneously cutting GHG emissions.

Footnotes

1. http://www.osti.gov/bridge/purl.cove...PRAO0M/native/

2. International Food Policy Research Institute.  2020 Vision for Food, Agriculture, and the Environment.  http://www.ifpri.cgiar.org/sites/def...ns/focus16.pdf

3. Wassman, R. et al. (2009). Agriculture and Climate Change: An Agenda for Negotiation in Copenhagen- Reducing Methane Emissions from Irrigated Rice. 2020 Vision For Food, Agriculture, and the Environment

4. ibid

Resources

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