Soil and water

Rising salinity threatens rice crops on Southeast Asia’s sunken coast

Prak Nhorn has no hope for his rice harvest this year.

“When I transplant seedlings, they die. The salt is still in the ground,” said the village farmer from Slab Ta Aon, a riverside village about 150 kilometers southwest of Cambodia’s capital, Phnom Penh. , and 4 kilometers from the green coast lined with mangroves of the province of Kampot.

The farmer said the salt water had destroyed the rice fields in Slab Ta Aon village over the past two years. Prak Nhorn, 55, doubts that he and the other villagers will be able to grow rice in the future.

Slab Ta Aon’s problem is not an environmental accident. It is a harbinger of a global environmental crisis that has been brewing for decades, destabilizing the food systems that feed millions of people.

Around the world, salt water is increasingly seeping inland from coasts, dirtying soils and fresh water. A complicated interplay between groundwater extraction, damming of rivers for hydroelectricity and mining of riverbeds is sinking shorelines as climate change lifts the seas, pulling seawater towards inland.

A rice farmer plants seedlings in Slab Ta Aon, Cambodia. (Elise Cutts/VOA)

River deltas are particularly vulnerable. Fan-shaped plains that form where rivers flow into the sea, deltas often have fertile soils thanks to nutrient-rich sediments brought in from upstream. The increase in salinity endangers these particular agricultural regions.

The threat is perhaps most severe in Asia, where vast “megadeltas” are vital to the cultivation of the continent’s staple crop: rice. High salinity can make it impossible to grow rice.

“You really see a solid layer…a white layer on the ground where the salt water came from,” said Bjoern Ole Sander of the International Rice Research Institute (IRRI). Rice plants growing in saline soil “look like straw”, he continued. “If you touch them, they are hollow. There is nothing.”

Food, drinking water at risk

In Southeast Asia, salt water threatens the rice fields of the Mekong and Red River deltas in Vietnam, as well as the deltas of the Chao Phraya River in Thailand and the Ayeyarwady River in Myanmar.

In South Asia, it degrades soils and contaminates drinking water in the densely populated Ganges and Brahmaputra delta in Bangladesh and India and in the Indus delta in Pakistan.

The Yangtze River Delta in China is also facing increased salinity.

Beyond Asia, saltwater intrusion affects the Nile Delta in Egypt and the Mississippi Delta in the United States, two important agricultural regions.

For subsistence farmers like Prak Nhorn, rising salinity directly threatens food security and access to clean water. About 76% of Cambodians live in rural areas and many depend on natural resources for food. This makes many of the country’s 17.2 million people vulnerable to changes in the environment. Undernutrition rates in Cambodia are around 15%.

Cambodian rice farmer Prak Nhorn.  (Elise Cutts/VOA)

Cambodian rice farmer Prak Nhorn. (Elise Cutts/VOA)

Cambodian farmers have been reporting salinity issues for years and “there is saltwater intrusion” in the country, said Hak Mao, director of Cambodia’s climate change department at the environment ministry. But “limited technical capacity” means the true scale of the problem in Cambodia is not known, he said.

In neighboring Vietnam, however, the costs of saltwater intrusion have been clear for decades.

“If there is fresh water, we can grow rice all year round,” said Khau Van Ngoan, a farmer from Long An province in Vietnam. “If there is none, nothing can be cultivated.”

Vietnam grows more than half of its rice in one region, the Mekong Delta.

The salinity there has “really increased”, said hydrologist Gijs Simons of FutureWater, a consultancy that uses satellite data to assess salinity for the Mekong River Commission (MCR). The area affected by high salinity, which makes it almost impossible to grow rice, has roughly “doubled since the 1990s or even almost tripled for a few years”, he said.

In the past, salt water infiltrated about 30 to 50 kilometers inland. Now it can reach areas more than 100 kilometers from the coast, said hydrologist Binh Doan Van of the German-Vietnamese University, who studies saltwater intrusion in the Mekong Delta. A particularly severe salinity intrusion in 2016 affected 270,000 hectares of rice, said Andrew Wyatt, who oversees projects in Southeast Asia for the environmental organization International Union for Conservation of Nature, or IUCN. Damage totaled about $455 million, or 1.5 percent of Vietnam’s annual rice yield.

Cambodian rice farmer Prak Nhorn says storms, floods and salt water are destroying the rice paddies in his village.  (Elise Cutts/VOA)

Cambodian rice farmer Prak Nhorn says storms, floods and salt water are destroying the rice paddies in his village. (Elise Cutts/VOA)

Alternative to shrimp

But it is possible to see the increase in salinity as an opportunity rather than a disaster.

Rice does not tolerate salt water, but shrimp can – and shrimp fetches a better price than the rice that Vietnam produces for export to low- and middle-income countries.

“Shrimp is a better deal than rice. It’s more lucrative,” said Dang Thi Vich, a shrimp farmer from Ben Tre province.

Some Mekong Delta farmers have taken advantage of this as salinity has increased, growing shrimp instead of rice during the dry season when conditions are most saline. The Vietnamese government and NGOs then launched programs to help more farmers adopt this rice-shrimp rotation system.

“Shrimp farming started about 20 years ago and it has become very popular,” Vich said. “Everyone was growing rice before that.”

Things change quickly. In 2018, 15% of farmers in the delta gave up rice farming for something else, usually shrimp farming, said Bradford Mills, an economist at Virginia Tech who has studied the change. The following year, another 10% stopped growing rice. Simons noted that the shift from rice paddies to shrimp ponds is visible in his satellite data.

Experts say the Vietnamese government plans to reduce rice cultivation and diversify the economy of the Mekong Delta. This will mean increasing shrimp and other aquaculture along the coast and growing “high quality” rice for export to rich countries. This diversification “is in line with Vietnam’s transition from a low-income country to a middle-income country,” Wyatt said.

But researchers have expressed concern that adaptations to rising salinity in Vietnam are coming at a social cost, widening the gap between rich and poor.

“Across the country, [shrimp farming] can be good,” Binh said. “But for [the] at the local level, for individuals, it is I think [it] still has some problems.

Ben Tre province farmer Nguyen Thi Be Lieu said she tried shrimp farming a few years ago, “but the business didn’t take off. We spent more than we earned, so we quit.

Switching from rice farming to shrimp farming is risky. Not everyone can afford it. Those who cannot – and do not receive assistance – have no choice but to sell or rent their land and migrate to find work.

There is also evidence that shrimp aquaculture is not always environmentally sustainable. Although Wyatt noted that the rice-shrimp rotation is more sustainable than growing rice or shrimp exclusively for land at the mouth of the Mekong, it is not a good solution wherever it is adopted. If there is not enough freshwater flow upstream, dry season shrimp ponds can leave salt in the ground, which over time makes it difficult to grow rice in the wet season. rains. Ponds can become so salty that even shrimp cannot survive.

Salinity is killing the harvest of Cambodian rice farmer Prak Nhorn.  (Elise Cutts/VOA)

Salinity is killing the harvest of Cambodian rice farmer Prak Nhorn. (Elise Cutts/VOA)

“Saline soils are bad for business, even for shrimp farming,” said Pham Van Bay, a farmer from Long An province. “There is absolutely nothing you can do with saline soil. .”

Aquaculture can also pollute waterways, a problem Binh says needs to be managed to ensure it remains sustainable and profitable for the future.

Still, if these challenges can be overcome, satisfying rich countries’ appetites for high-quality shrimp and rice could pay off for many farmers and for Vietnam’s economy as a whole, Binh and Wyatt said.

“How can we eat rice? »

The question, Sander said, “is of course: where do you produce the rice instead? Because the demand is still there. And shrimp cannot replace rice on people’s plates.

A rice paddy in Slab Ta Aon, Cambodia.  (Elise Cutts/VOA)

A rice paddy in Slab Ta Aon, Cambodia. (Elise Cutts/VOA)

Vietnam is the third largest rice exporter in the world and more than 90% of its exports come from the Mekong Delta. Countries that are “large importers of rice…are also affected by the impacts of climate change and the impacts of salinity in the Mekong Delta,” Sander said. For example, the Philippines imports nearly 80% of its rice from Vietnam.

The demand for rice increases as the world’s population increases. IRRI estimates that global rice production needs to increase by 1% to 1.2% each year to keep rice prices low enough to be affordable for billions of grain-dependent people.

For the Mekong Delta, Binh said adapting to increased salinity involves a combination of expensive infrastructure to keep salt water out – which can lead to its own environmental problems – and changes in the way people people live and work, such as the adoption of rice-shrimp systems. Other agricultural deltas face similar choices.

Countries that import a lot of rice from regions affected by salinity will have to find new sources to meet their growing demand for rice, or consumers will simply pay more. Many farmers will have to adapt. And some will just need to find a way to survive.

Suos Sovann lives close to the Prak Nhorn farm in the village of Slab Ta Aon. She is a rice farmer — or was. Salt water now floods his 7,000 square meter farm every year, rendering his soil infertile.

Unable to grow rice for herself and her family, Suos Sovann now depends on money sent by two of her children who work in a nearby garment factory. Together they send her about $50 a month. She will spend $30 of it on rice.

She wonders if maybe her children could send more money, but she doesn’t dare ask. There’s nothing to do but put up with it, she said.

“If we don’t cultivate,” Suos Sovann asked, “how can we have rice to eat?”

The Vietnamese journalist who contributed to this report is not named for his safety.