The Reimagining of Rice Farming
As the planet gets hotter, an essential food for the world’s poorest is imperiled.
Rice is in trouble as the Earth heats up, threatening the food and the livelihood of billions of people. Sometimes there is not enough rain when seedlings need water, or too much when the plants need to keep their heads above water. As the sea intrudes, salt ruins the crop. As nights warm, yields go down.
These hazards are forcing the world to find new ways to grow one of its most important crops. Rice farmers are shifting their planting calendars. Plant breeders are working on seeds to withstand high temperatures or salty soils. Hardy heirloom varieties are being resurrected.
And where water is running low, as it is around the world, farmers are letting their fields dry out on purpose, a strategy that also reduces methane, a gas that rises from paddy fields.
The climate crisis is particularly distressing for farmers with little land, including hundreds of millions of farmers in Asia. “They have to adapt,” said Pham Tan Dao, the irrigation chief for Soc Trang, a province in Vietnam, one of the world’s biggest rice-producing countries. “Otherwise they can’t live.”
In China, a study found that extreme rainfall had reduced rice yields over the past 20 years. India limited rice exports out of concern for having enough to feed its own people. In Pakistan, heat and floods destroyed harvests, while in California, a long drought led many farmers to fallow their fields.
Worldwide, rice production is projected to shrink this year, because of extreme weather.
Fifty years ago, the world needed to produce much more rice to stave off famine. High-yielding hybrid seeds, grown with chemical fertilizers, helped. In the Mekong Delta in Vietnam, farmers produced as many as three harvests a year, feeding millions at home and abroad.
But around the world, that intensive production has depleted aquifers, driven up fertilizer use, reduced the diversity of rice breeds that are planted, and polluted the air with the smoke of
burning rice stubble. On top of that, climate change has upended the rhythm of sunshine and rain that rice depends on.
Farmers in the Mekong Delta no longer plant a third rice crop some years, when the rains are paltry.
Perhaps most worrying, because rice is eaten every day by some of the world’s poorest, elevated carbon dioxide concentrations in the atmosphere deplete nutrients from each grain. Rice also accounts for about 8 percent of global methane emissions.
Rice is the staple grain for an estimated three billion people. It is biryani and pho, jollof and jambalaya — a source of tradition, and sustenance.
“It’s a question of producing more with less,” said Lewis H. Ziska, a professor of environmental health sciences at Columbia University in New York. “How do you do that in a way that’s sustainable? How do you do that in a climate that’s changing?”
Vietnam is preparing to take about 100,000 hectares in the Mekong Delta out of production.
In 1975, facing famine after war, the nation resolved to grow more rice. It eventually became the world’s third-largest rice exporter after India and Thailand, with the Mekong Delta its most prized region.
At the same time, the Mekong River was reshaped by humans. Starting in southeastern China, it meanders through Myanmar, Laos, Thailand and Cambodia, interrupted by many dams. By the time it reaches Vietnam, there is little freshwater left to flush out seawater seeping inland. Rising sea levels bring in more seawater. Irrigation canals turn salty. The problem is going to get worse as temperatures rise.
Mr. Pham said where saltwater used to intrude 30 kilometers or so during the dry season, it can now reach 70 kilometers inland.
Climate change brings other risks. You can no longer count on the monsoon season to start in May. And so in dry years, farmers now rush to sow rice 10 to 30 days earlier than usual. In coastal areas, many rotate between rice and shrimp, which like a bit of saltwater.
Shrimp bring in high profits, but also high risks. Disease sets in easily. The land becomes barren.
Dang Thanh Sang, 60, a rice farmer in Soc Trang, plants rice when there is freshwater in the canals, and shrimp when seawater seeps in. Rice cleans the water. Shrimp nourishes the soil. “It’s not a lot of money like growing only shrimp,” he said. “But it’s safer.”
Elsewhere, farmers will have to shift their calendars for rice and other staple grains.
At Arkansas State University, Argelia Lorence’s laboratory holds 310 kinds of rice seeds.
Many are ancient, rarely grown now. But they hold genetic superpowers that Dr. Lorence, a plant biochemist, is trying to find, particularly those that enable rice plants to survive hot nights. She has found two such genes so far. They can be used to breed new hybrid varieties.
Dr. Lorence is among an army of rice breeders developing new varieties for a hotter planet. Multinational seed companies are heavily invested. RiceTec, from which most rice growers in the southeastern United States buy seeds, backs Dr. Lorence’s research.
Critics say hybrid seeds and the chemical fertilizers they need make farmers heavily dependent on the companies’ products, and because they promise high yields, effectively wipe out heirloom varieties that can be more resilient.
The new frontier of rice research involves Crispr, a gene-editing technology that U.S. scientists are using to create a seed that produces virtually no methane. (Genetically modified rice remains controversial, and only a handful of countries allow its cultivation.)
In Bangladesh, where rice is eaten at every meal, researchers have produced new varieties for the climate pressures that farmers are dealing with.
Some can grow when submerged in floodwaters for a few days. Others can grow in soils that have turned salty. The country will need new rice varieties that can grow with less fertilizer, which is now heavily subsidized by the state.
In the United States, the main rice-growing area is spread across the hard clay soil near where the Mississippi River meets the Arkansas River. Because of climate change, nights there are hotter. Rains are erratic. And there is a problem created by the success of intensive rice farming: Groundwater is running low.
Enter Benjamin Runkle, an engineering professor from the University of Arkansas at Fayetteville. Instead of keeping rice fields flooded at all times, as growers have always done, he suggested that farmers let the fields dry out a bit, then let in the water again, then repeat.
Mark Isbell, a second-generation rice farmer, signed up.
On the edge of Mr. Isbell’s field, Dr. Runkle erected a tall white device that measured the gases produced by bacteria stewing in the flooded fields. His experiment, done over seven years, concluded that by not flooding the fields continuously, farmers can reduce rice methane emissions by over 60 percent.
Other farmers have been planting rice in rows, like corn, and leaving furrows in between for the water to flow. That, too, reduces water use and, according to research in China, where it has been common for some time, cuts methane emissions.
For Mr. Isbell, the most important finding was that his energy bills to pump water were reduced: “There are upsides to it beyond the climate benefits.”
By cutting his methane emissions, Mr. Isbell was also able to sell carbon credits, which is when polluting businesses pay someone else to make emissions cuts. But he made very little money from it.
However, there will be more upsides. For farmers who can demonstrate emissions reductions, the Biden administration is offering U.S. funds for what it calls “climate smart” projects. Agriculture Secretary Tom Vilsack came to Mr. Isbell’s farm last fall to promote the program. Mr. Isbell reckons the incentives will persuade other rice growers to adopt alternate wetting and drying.
“We kind of look over the hill and see what’s coming for the future, and learn now,” said his father, Chris Isbell.