Improved Rice Cultivation
Rice is the staple food of 3 billion people, providing one-fifth of calories consumed worldwide. Its cultivation is responsible for at least 10 percent of agricultural greenhouse gas emissions and 9 to 19 percent of global methane emissions. That is because flooded rice paddies are ideal anaerobic environments for methane-producing microbes that feed on decomposing organic matter, a process known as methanogenesis.
There are four general techniques, best used in combination, to improve rice production and reduce emissions:
- Water: Mid-season drainage and alternate wetting and drying improve aerobic conditions.
- Nutrients: More balanced application of nutrients reduces methane emissions while supporting yields.
- Plant varieties: Rice varieties (cultivars) that are less water-loving can be used in more aerobic environments.
- Tillage: Techniques for seeding rice without tilling the ground maintain stable soils.
These techniques can make rice production efficient, dependable, and sustainable, helping to meet growing demand for this staple food without causing warming. Mid-season drainage alone reduces methane emissions by 35 to 70 percent. Given that many rice farming methods are long-entrenched customs, change requires helping farmers see what results are possible, cultivating necessary knowledge and skills, and implementing incentives that make new methods compelling.
“their breed has fed our folk”: Van Tri, Phan. “Grains of Rice.” In An Anthology of Vietnamese Poems., edited and translated by Huynh Sanh Thong. London: Yale University Press, 1996.
one-fifth of calories consumed: Elert, E. “Rice by the Numbers: A Good Grain.” Nature, 514, no. 7524 (2014): S50-S51.
rice cultivation…emissions: Adhya, T. K., et al. “Wetting and Drying: Reducing Greenhouse Gas Emissions and Saving Water from Rice Production.” Working Paper, Installment 8 of Creating a Sustainable Food Future. Washington, D.C.: World Resources Institute, 2014; Forster, P., et al. “Changes in Atmospheric Constituents and in Radiative Forcing.” In Climate Change 2007: Thee Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2007.
[more] methane…as the planet gets hotter: Ziska, L. H., P. R. Epstein, and W. H. Schlesinger. “Rising CO2, Climate Change, and Public Health: Exploring the Links to Plant Biology.” Environmental Health Perspectives 117, no. 2 (2009): 155–158.
Methane [vs.] carbon dioxide: Myhre, Gunnar, Drew Shindell, François-Marie Bréon, William Collins, Jan Fuglestvedt, Jianping Huang, Dorothy Koch et al. “Anthropogenic and natural radiative forcing.” In Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2013.
“discovered almost by accident”: de Laulanié, Henri. “Technical Presentation of the System of Rice Intensification, Based on Katayama’s Tillering Model.” Madagascar: Association Tefy Saina, 1992. http://sri.ciifad.cornell.edu/aboutsri/Laulanie.pdf.
“a less-is-more ethic”: Broad, William J. “Food Revolution That Starts with Rice.” New York Times. June 17, 2008.
[SRI] practiced by 4 million to 5 million farmers: Vidal, John. “India’s Rice Revolution.” The Guardian. February 16, 2013.
Sumant Kumar…world-record yield: Diwakar, M.C., Arvind Kumar, Anil Verma, and Norman Uphoff. “Report on the World Record SRI Yields in Kharif Season 2011 in Nalanda District, Bihar State, India.” Agriculture Today. June 2012.
[benefits of] transplanting single seedlings: Bhatt, K.N. “System of Rice Intensification for Increased Productivity and Ecological Security: A Report.” Rice Research: Open Access 3 (2015): 147.
mid-season drainage…reduces methane: Adhya et al, “Wetting and Drying”; Yu, K., G. Chen, and W.H. Patrick. “Reduction of Global Warming Potential Contribution from a Rice Field by Irrigation, Organic Matter, and Fertilizer Management.” Global Biogeochemical Cycles 18, no. 3 (2004): GB3018.
yields…seed use…water inputs: Latham, Jonathan. “How Millions of Farmers Are Advancing Agriculture for Themselves.” Independent Science News. December 3, 2012; Surridge, Christopher. “Rice Cultivation: Feast or Famine?” Nature 428 (2004): 360-361.
“not intrinsically labor-intensive”: Charles, Dan. “Unraveling the Mystery of a Rice Revolution.” National Public Radio. May 3, 2013.
Farm incomes can double: Namara, Regassa E., Parakrama Weligamage, and Randolph Barker. “Prospects for Adopting System of Rice Intensification in Sri Lanka.” Research Report 75. Colombo, Sri Lanka: International Water Management Institute, 2004.
spread to some forty countries: Bhatt, “System.”
Improved Rice Cultivation
Project Drawdown defines improved rice cultivation as: a set of practices to reduce methane emissions from paddy rice production using alternate wet and dry periods and other strategies. This solution replaces conventional paddy rice production in mechanized (non-smallholder) regions.
Paddy rice farming is a major source of greenhouse gas emissions largely in the form of methane, as flooded rice paddies provide a suitable anaerobic environment for methanogenesis. Yet, rice is a world staple crop of extreme importance, particularly in Asia. Thus, low-methane rice production techniques are sorely needed. Drawdown investigated two categories of low-methane rice production: improved rice cultivation (profiled here), with techniques suitable to both small- and large-scale operations, and System of Rice Intensification, currently limited to the smallholder context.
Improved rice cultivation practices include: changes to water management (alternate wetting and drying); fertility management; use of aerobic cultivars; no-tillage; and direct seeding. Data was collected only from studies that used two or more of these practices.
Total Land Area 
Total available land is 108 million hectares, representing non-smallholder rice production.  Current adoption  of improved rice cultivation is estimated at 2 million hectares, based on meta-analysis of 21 data points from 5 sources.
Adoption Scenarios 
Six custom adoption scenarios were developed based on the estimation of low, medium, and high adoption rates from 36 data points from 3 sources. Some of these scenarios include early peak adoption of the solution by 2030.
Impacts of increased adoption of improved rice cultivation from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.
- Plausible Scenario: This scenario estimates the practice of improved rice cultivation on 58.2 million hectares by 2050.
- Drawdown Scenario: Based on the most aggressive and early-peak-adoption custom scenarios, this scenario yields adoption of the solution on 85.7 million hectares.
- Optimum Scenario: Based on the most aggressive and early-peak-adoption custom scenarios, this scenario yields adoption of the solution on 107.6 million hectares, representing almost 100 percent adoption on allocated land.
Adoption of the solution not only mitigates greenhouse gas emissions, but also saves significant amounts of irrigation water used in rice cultivation. As a reflection of improved rice cultivation's many benefits, one of the custom adoption scenarios assumes 100 percent adoption of the total allocated area under the solution.
Emissions, Sequestration, and Yield Model
Methane emissions reduction from improved rice cultivation is set at 5.6 tons of carbon dioxide-equivalent per hectare per year, based on 45 data points from 10 sources. Nitrous oxide emissions reduction is calculated at 0.4 tons of carbon dioxide-equivalent per hectare per year, based on 7 data points from 2 sources. Sequestration rates are set at 1.45 tons of carbon per hectare per year, based on 25 data points from 3 sources.
Yield reductions compared to business-as-usual annual cropping were set at 2.9 percent, based on meta-analysis of 33 data points from 7 sources.
First costs of improved rice cultivation are US$0 per hectare, as the practices use existing equipment and infrastructure.2 For all agricultural solutions, it is assumed that there is no conventional first cost, as agriculture is already in place on the land. Net profit is calculated at US$537.28 per hectare per year for the solution (based on meta-analysis of 15 data points from 5 sources), compared to US$30.47 per year for the conventional practice (based on 6 data points from 6 sources).
Drawdown’s Agro-Ecological Zone model allocates current and projected adoption of solutions to the planet’s forest, grassland, rainfed cropland, and irrigated cropland areas. Adoption of improved rice cultivation was the second-highest priority for cropland, following System of Rice Intensification.
Total adoption in the Plausible Scenario is 58.2 million hectares in 2050, representing 53.8 percent of the total suitable land. Of this, 56.2 million hectares are adopted from 2020-2050. The emissions impact of this scenario is 11.3 gigatons of carbon dioxide-equivalent by 2050. Net cost is US$0. Net savings is US$519.1 billion. Yield reduction is 37.0 million metric tons between 2015 and 2050.
Total adoption in the Drawdown Scenario is 85.7 million hectares in 2050, representing 79.3 percent of the total suitable land. Of this, 83.7 million hectares are adopted from 2020-2050. The impact of this scenario is 16.7 gigatons of carbon dioxide-equivalent by 2050.
Total adoption in the Optimal Scenario is 107.6 million hectares in 2050, representing 99.9 percent of the total suitable land. Of this, 105.6 million hectares are adopted from 2020-2050. The impact of this scenario is 20.1 gigatons of carbon dioxide-equivalent by 2050.
The Intergovernmental Panel on Climate Change (Smith et al, 2007) estimates emissions reduction of 0.2 gigatons carbon dioxide-equivalent per year by 2030 for rice management. Between the three Scenarios, Drawdown's two rice solutions combined provide 0.16-0.26 gigatons carbon dioxide-equivalent per year by 2030, a close match to this benchmark.
Reduced rice yield in this solution is offset by increases in rice yield in the System of Rice Intensification solution.
It would be useful to obtain more rice production financial data points for the conventional case. Additional data on current and projected adoption would be useful as well.
Rice is a staple crop of critical importance, particularly in Asia. Rice production is currently a major contributor of methane emissions. Fortunately, low-methane rice production systems are ready to be scaled up. Wide adoption of these practices can have a significant impact on climate change mitigation.
 To learn more about the Total Land Area for the Food Sector, click the Sector Summary: Food link below.
 Determining the total available land for a solution is a two-part process. The technical potential is based on the suitability of climate, soils, and slopes, and on degraded or non-degraded status. In the second stage, land is allocated using the Drawdown Agro-Ecological Zone model, based on priorities for each class of land. The total land allocated for each solution is capped at the solution’s maximum adoption in the Optimum Scenario. Thus, in most cases the total available land is less than the technical potential.
 Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.
 To learn more about Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Land Use Sector-specific scenarios, click the Sector Summary: Food link.
 For more on Project Drawdown’s Food Sector integration model, click the Sector Summary: Food link below.
Full models and technical reports coming in late 2017.