From a young age, Dong Van Canh watched as the paddy fields in Vietnam’s Mekong Delta burned after each harvest, blackening the skies and flooding the air with greenhouse gases.
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Rice cultivation, the staple food par excellence in Asia, is responsible for about 10% of global methane emissions, which trap about 80 times more heat than carbon dioxide.
Usually associated with cows, methane is also produced by bacteria that thrive in flooded paddy fields and thrive when leftover straw rots in the fields after harvest.
The scientists’ message: Rice must not be ignored in the fight against emissions.
Today, one rice farmer, Canh, 39, has turned his rice straw, which he no longer lets rot in the fields, to mushroom production and organic fertilizer production.
“If we can sell the straw and make money, all the profits are ours,” he told AFP, running his fingers through a pile of manure that will soon become nutritious food for other Mekong cultures.
The transition to cleaner rice farming is supported by the International Rice Research Institute (IRRI), a well-established NGO in Asia.
“Everyone here is for this initiative,” which aims to recycle straw as an ingredient in nutritious food for other crops, he explains.
reduce emissions
Not new, these initiatives have multiplied over two years after a hundred countries pledged to reduce methane emissions by 30% by 2030.
Like Indonesia and Bangladesh, Vietnam is one of the signatories, but not the two largest producers, India and China.
In Can Tho province, the harvest is coming to an end and farmers are pushing small carts overflowing with bales of straw, which are then soaked and spread out to grow mushrooms for sale.
The straw mixture is then machine processed into compost and sold for around 15 cents per kilo.
“Some farmers used to do this manually, but it was too labor-intensive. We have cut costs in half and will expand to meet market demand,” says Le Dinh Du, head of the local crop protection department.
“The rice has a nice journey. We don’t waste anything.”
Reuse rice straw
According to Vietnamese authorities, irrigated rice cultivation was responsible for almost half of methane emissions in 2019.
According to the CGIAR, an international center for agricultural research, the straw reuse technique has been taught to “farmers and local agricultural officials” across the country.
How many actually do this is unclear.
According to the World Bank, more than 80% of the rice straw in the Mekong Delta was burned last year.
According to the researchers, straw management, coupled with another method of breaking up the layer of stagnant water in paddy fields to replenish oxygen and reduce bacteria, “has the potential to significantly reduce greenhouse gas emissions. Greenhouse effect.”
In fact, unlike other crops, rice has “a layer of standing water on the field, which means there is no air exchange between the soil and the atmosphere,” explains Bjoern Ole Sander, who directs IRRI in Vietnam.
“These bacteria eat organic matter and produce methane.”
According to Vietnamese authorities, this drying of paddy fields has been taken up by a third or a half of the rice-growing area in An Giang province (south), depending on the season, and covered more than 200,000 hectares in 2019, double the amount in 2018.
Farmers who have taken the plunge into the Mekong take pride in the way it is grown and being able to maximize its potential and income.
First, “it complicates our lives,” says Canh. “But once we understand how to use the straw, things are easier.”