The System of Rice Intensification in Sustainable AgricultureCatherine Webb
Worldwide, the total production of food calories has increased by roughly one-third since 1961. Rapid population growth drives increased demand for food. This demand for food then drives increased land use, necessitating practices like deforestation, and results in disrupted ecosystems as well as 24% of greenhouse gas emissions worldwide. Rice has a significant role in this vicious cycle, both in being a problem and – through the System of Rice Intensification – a part of the solution.
Rice is one of the most consumed foods in the world, providing one-fifth of calories consumed worldwide, and rice fields cover about 11% of global arable lands. As a result, rice production and cultivation are crucial to global food security. However, rice production contributes quite significantly to climate change. Although rice paddies can sequester carbon dioxide emissions, they are sizable producers of methane and nitrous oxide, two greenhouse gases that drive climate change.
According to the 2007 IPCC report on Impacts, Adaptation, and Vulnerability, methane, and nitrous oxide compositionally have 298 and 25 times more global warming potential (GWP) as compared to CO2. Because conventional rice cultivation practices release unparalleled quantities of methane and nitrous oxide, the GWP of rice production is 169% higher than other staple crops such as wheat and maize.
Rice Production and Cultivation
Rice production and cultivation have a profound impact on climate change not only due to high demand but also as a result of unsustainable crop management. Like wheat and maize, the yields of rice crops dramatically increased during the Green Revolution, a period between 1950 and the 1980s of rapid agricultural technological advancement. Unlike wheat or maize, this grain is not grown in aerobic soils, but in anaerobic water-flooded rice paddies.
This wet environment is a welcoming host to microbes that survive on decomposing organic matter and produce methane as a byproduct. Nitrous oxide forms under particularly wet conditions when there is excess nitrogen that cannot be used by the plant life. As a result, widespread rice cultivation comprises 9-19% of global methane emissions. Climate change extremes including drought, high temperatures, and inconsistent rainfall now threaten consistent and efficient crop production and, correspondingly, global food security. As populations grow and rice demand increases, climate-smart practices must be implemented without compromising crop productivity.
The System of Rice Intensification
The prevailing notion of agricultural intensification is associated with Green Revolution strategies of high water, seed, and fertilizer input. However, this strategy proves to have a high economic, social, and environmental cost to farmer and community welfare, food security, and climate stability.
Alternatively, The System of Rice Intensification (SRI) is an agroecological crop management system that was developed on Madagascar in the 1980s to address these external costs and pave the way for a future of sustainability in rice production. SRI is built on practices that both reduce agricultural inputs and attain increased yields and has documented success in more than 50 countries in Asia, Africa, and Latin America. These practices include:
- Seedling Care: transplant young seedlings for maximum growth, avoid root disturbance during transplantation, provide plants wider spacing
- Controlled Water Irrigation: keep the soil moist but not continuously flooded
- Enhancing Soil Health: use natural fertilizers (like compost), use a rotating hoe to manage weeds, and make small holes in the soil to allow air, water, and nutrients to cycle through
Implementing SRI practices improves plant, soil, water, and nutrient management. These sustainable practices promote the growth of deeper root systems and increase the quantity and quality of important soil organisms. Under SRI management, the same varieties planted on the same soil generally produced 20 to 50% higher yields, sometimes with 100% or higher yield increases. These practices have proven to be effective, achieving significantly higher yields than conventional rice crop production without first requiring a period of soil regeneration or improved seed varieties.
Greater yields and reduced expenses on inputs such as fertilizer and water directly improve farmer income and local economies. In the West Bengal state of India, researchers found an average of 67% increase in net income ha–1 compared to farmers’ current practices, and in Tamil Nadu and Andhra Pradesh states, studies found 31 and 41% net increases in income when using SRI practices. Farmers spend less money on agricultural inputs and increase rice yields, so their economic bottom line significantly improves. As calculated by Project Drawdown, if SRI can expand from 6.7 million hectares to 40-52 million hectares by 2050, 333-510 million additional tons of rice could be produced. This would earn farmers an additional $574-817 billion in profit in their lifetime, with a lifetime operational savings of $14-21 billion.
Meeting global food security goals becomes more and more daunting as climate change continues to put limits on agricultural production. Rice production has particularly important implications for climate change, with about 3 million people dependent on this staple crop for sustenance and survival. Global rice production must transition from being a hefty contributor to climate change to a system that supports mitigation and adaptation. By investing in SRI, investors can be a part of a sustainable solution that positively impacts climate change and food security.