- To fight food insecurity and climate change, Senegal is increasingly employing a relatively new strategy for growing rice, known as the “system of rice intensification” (SRI).
- Developed in Madagascar in the 1960s, this method of growing rice intentionally stresses the plants, which allows the farmer to use less water, improves soil fertility, decreases methane emissions, and, most importantly, increases yields.
- Critics of the method say it’s more a list of principles than set rules, with some farmers also turning to herbicides to deal with weeding.
- Still, the method has been scientifically shown to provide numerous benefits for growing rice in drier climates.
In Saint Louis, northern Senegal, farmers have had to buy extra rice for as long as anyone can remember. “Normally, people can only live off the rice they grow for a few months,” according to Abdoulaye Sy, director at the government’s National Agricultural and Rural Advisory Agency (ANCAR). The rest of the time, people buy rice from wholesalers, hoisting 20-kilogram (44-pound) burlap sacks onto communal minibuses or horse-drawn carts for the long ride home.
But since officials at ANCAR introduced a new method for growing rice, called the “system of rice intensification” (SRI), yields have more than doubled. For the first time, according to ANCAR, families can live off their own crop and make money from the surplus.
“Our mission is to help farmers achieve stability,” Sy said. “But we have good luck, since there’s another benefit: SRI saves water and combats climate change, too.”
Developed in Madagascar in the mid-1960s, SRI has been spreading across Africa for the past 20 years, driven by a group of enthusiastic advocates with international support. It’s increasingly seen by officials as a way to decrease methane emissions; alongside four other countries, Senegal committed to fund new SRI projects as “mitigation actions” in its 2020 Nationally Determined Contribution (NDC), its pledge under the Paris climate deal. In January 2023, after years of testing and pilot programs, the Sahara and Sahel Observatory, an intergovernmental collaboration that represents 13 West African states, launched a new project, extending SRI use to more than 150,000 farmers across West Africa.
Today, 70% of Senegalese work in agriculture, although less than a fifth of the country’s land is arable. Food insecurity remains a serious concern in Senegal, where the two largest crops by production value are cash crops: sugarcane and groundnuts. Historically, the government imported staple foods like rice, wheat and maize to fill the gap between the population’s needs and domestic production. The heavy influx of grains made Senegal one of the world’s largest net importers of food, totally dependent on foreign-grown calories.
To meet its current demand, Senegal must grow or buy more than 2 million metric tons of rice each year. The country has invested in subsidies to boost domestic rice production. Yet in such a dry region, growing rice can be difficult for small-scale farmers. Conventional rice production uses flooded fields, which encourage the crop to grow by drowning out weeds. But in Senegal, where surface water evaporates quickly and farmers lack the infrastructure to manage it, keeping rice crops submerged is a difficult task.
“That’s where SRI offers us this opportunity,” said Bancy Mati, an agronomist at Jomo Kenyatta University in Kenya who has spent years studying SRI across Africa. “SRI methods increase yields, reduce seed use, and save water, all at the same time.”
What is SRI?
The SRI methodology was developed by a French priest, Henri de Laulanié, who worked alongside farmers with few resources in rural Madagascar from the 1960s till his death in 1995. Laulanié claimed he developed SRI’s core principles simply by observing his rice plants, which he dubbed his “masters.”
Encouraged by the productivity of his crops, Laulanié created a nonprofit called Tefy Saina, which collaborated on SRI research projects with Cornell University scientist Norman Uphoff. After several years of trials, Uphoff and his partners began sharing results with the scientific community. The conclusion was clear: across the world, despite regional differences in soil ecosystems, climate and infrastructure, SRI produced more rice with less water.
The SRI methodology consists of several core principles: minimize competition between plants, balance the availability of water and oxygen in the soil, and build up soil fertility.
In practice, this means farmers should transplant rice seedlings at a young age and raise them in unflooded nurseries, spaced far apart from each other. After transplanting, farmers should either add small amounts of water each day or alternate between flooding and drying the land.
In conventional rice agriculture, farmers toss clusters of seeds into a wet seedbed. After a few weeks, they transplant the young seedlings into flooded fields. But when the earth is saturated, research suggests, plant roots break down, and some of the small organisms that help soil ecosystems thrive suffocate without oxygen.
“The rice plant is a water-loving plant,” Mati said, “but there is no need to waste water flooding the paddy unnecessarily.”
When plants experience just a small amount of water stress, their root systems expand in search of moisture.
“If plants are grown to have bigger, deeper root systems, they can manage with less rainfall or irrigation, because they can access soil moisture,” Uphoff said. By deliberately stressing their crops, farmers are able to produce higher yields with SRI, as the plants have stronger roots and less competition with other seedlings.
Unflooded soil allows weeds to grow and compete with rice. To help the crop grow unimpeded, the SRI methodology suggests farmers remove weeds with a simple hand weeder, which aerates the soil and eliminates competition for the rice crop. It’s a labor-intensive process, but hand weeding helps reinforce the soil ecosystem.
“SRI uses less seed and less water,” Mati said. “It helps farmers make the most of what they have.”
William Settle, a researcher at the United Nations’ Food and Agriculture Organization, introduced SRI to Senegal in 2003, doubling yields on rice farms along the Senegal River . Soon after, several SRI projects followed under the supervision of Peace Corps volunteers and local researchers. Slowly, the system began to attract attention and gain momentum.
In 2014, 13 nations joined together under the West African Agricultural Productivity Program, using World Bank funding to spread SRI techniques to tens of thousands of farmers. The project proved an enormous success, raising yields across the region. In their summary report, researchers concluded that “the additional quantity of rice produced because farmers used SRI during the 2015/2016 growing season alone is estimated at … 20,113 tons of milled rice,” worth more than $10 million.
“Rice is grown across West Africa, from desert to forests, and SRI has worked in all of them,” Sy said.
The most recent initiative, which invests more than $14 million into rice systems that use SRI along with more sustainable soil and water management, aims to address multiple challenges at the same time. ANCAR, the rural advisory agency, was chosen to implement the project in Senegal. While picking farming communities to partner with, Sy said, ANCAR tried to prioritize vulnerable groups, including women and girls, the elderly, displaced people, and people living with HIV/AIDS.
“By using this approach,” according to the project’s concept report, researchers hope to “respond to increasing rice consumption needs, strengthen the livelihoods of rice farming communities, [and] improve the overall national economic well-being.”
With temperatures rising across the globe, the U.N. predicts Senegal will experience up to 20%, less rainfall than normal, jeopardizing the security and livelihoods of the more than 5 million Senegalese who work in agriculture. The Senegalese government is also preparing to combat the effects of desertification, as the eastern desert spreads deeper into the country’s center.
By minimizing water use, SRI helps farmers make the most of every drop. Plants grown under SRI procedures, according to a 2017 Oxfam report, can withstand drought thanks to their especially deep and broad root systems, which allow them to wring more moisture from dry ground.
Yet the process not only fortifies farmers against the impacts of rising temperatures; it may also help farmers cut back on their own climate impact.
In traditional flooded fields, the oxygen-starved soil keeps weeds from competing with rice. Yet it also provides the perfect breeding ground for methanogens: microbes that produce methane, which feed on the nutrition excreted by the rice’s roots. The longer the flooding lasts, the more bacteria build up and the more methane they release into the atmosphere.
Methane, which is responsible for about 30% of the current rise in global temperatures, absorbs more energy than carbon dioxide in the atmosphere, making it far more potent than other greenhouse gases.
Per ton of protein, rice’s greenhouse gas impact is much lower than that of meat or other animal-based foods. But compared to other grains like wheat or corn, rice has an outsized effect on the climate, contributing up to 12% of the world’s methane emissions.
Under SRI management, the methane-bubbling, oxygen-deprived pools are replaced with moist, well-aerated soil. The microbial balance swings against methanogens, cutting back methane emissions. Well-maintained agricultural fields can also act as a carbon sink.
“Collectively, these large schemes can sequester thousands of tons of carbon dioxide,” Mati said.
Eleven countries in total have added SRI to their NDCs either as a mitigation or adaptation strategy to fight climate change and adapt to its impacts. In its action plan, the Senegalese government committed to funding 28,500 hectares (70,400 acres) of SRI-grown rice, highlighting the system’s potential to “reduce, at the same time, the volumes of water used and the quantities of methane emitted.”
Proponents of SRI admit the methodology isn’t a cure-all. SRI isn’t easy to apply. Irrigating and draining rice fields repeatedly, as the system advises, may not be feasible in areas where farmers don’t have strict control over their water supplies. Some may not be able to transplant all of their seedlings, and might choose to just toss seeds across the soil, a practice called “broadcasting.”
Farmers may also rely on herbicides to prevent weeds from choking out their crops if they don’t have the time or ability to pull weeds by hand. According to a 2020 paper published in the journal Agroecology and Sustainable Food Systems, some SRI proponents either recommend or tolerate this practice to reduce the amount of labor and time needed. While some farmers practice organic SRI without using herbicides, it remains “a special subset of the range of SRI practices.”
Moreover, critics say the methodology has become diluted, since it consists of principles rather than practices, and is often applied with most, but not all, of the principles in mind. The label SRI, according to a 2016 study published in the Wageningen Journal of Life Sciences, “encompasses a range of practices that depend heavily on farmers’ attitudes, household capacities, socio-economic contexts and local institutional factors.” In other words, different farmers may have their own ideas about what SRI looks like — and those may not always hold up to the rigors of science.
In response, several SRI advocates say the system’s strength lies in this flexibility. “For me, SRI is about ideas, since farmers can’t always use every single technique,” Sy said.
Uphoff said farmers ought to simply decide which tactics work best for them. “SRI is more appropriately thought of as an adjective rather than a noun,” he said. “It’s a set of insights to help rice plants become more robust and productive — one approach among many.”
Sy said he hopes that as SRI becomes more popular among farmers, better equipment, education and institutional support will become available.
“For SRI to really affect self-sufficiency, we need many more farmers to adopt it,” he said. “It’s not enough to have projects in different places — it must be a national strategy.”
He added, “We don’t want to buy rice from other countries anymore.”
Hidayati, N., Triadiati, T., & Anas, I. (2018). Rooting system of rice cultivated under system of rice intensification (SRI) method which improving rice yield. Hayati Journal of Biosciences, 25(2), 63-69. doi:10.4308/hjb.25.2.63
Conrad, R., Erkel, C., & Liesack, W. (2006). Rice Cluster I methanogens, an important group of Archaea producing greenhouse gas in soil. Current Opinion in Biotechnology, 17(3), 262-267. doi:10.1016/j.copbio.2006.04.002
Deb, D. (2020). Is the system of rice intensification (SRI) consonant with agroecology?. Agroecology and Sustainable Food Systems, 44(10), 1338-1369. doi:10.1080/21683565.2020.1779165