Biodiversity benefits: Rice-fish farming in ChinaThe 2000-year-old practice of raising fish in rice fields boosts yields, preserves biodiversity, reduces chemicals and fights malaria.
But that’s what the Chinese and other Asians have done for centuries: it may be fish and rice not fish and chips, but this marriage of agriculture and aquaculture is an all-too rare biodiversity success story.
Rice-fish farming “epitomizes an ecosystems approach” which contributes to “eco-environmental benefits and sustainable development” says the UN Food and Agriculture Organization (FAO) in a 2009 report by researcher Miao Weimin.
Heaven on earth to the ancient Chinese was a place that provided plenty of rice and fish.
Ever-ingenious, they began cultivating these fundamentals of the Chinese diet together, putting baby carp into their paddies as they planted rice seedlings. Come harvest time, the fish were ready for the pot.
Rice-fish farming in China can be traced back over 2000 years. But in the 1960s and 1970s the Green Revolution swept through Asia, bringing with it more intensive rice farming using large amounts of fertilizers, herbicides and pesticides, all toxic to fish. Rice-fish farming collapsed.
The government revived it in the 1980s and 1990s, however, and the rice-fish farm area increased from 648,000 hectares in 1985 to 1.55 million hectares in 2007 while fish production leapt from 81,700 tons to 1.16 million tons, according to the FAO.
Today China gets more fish products from fish farming than from the sea, and rice-fish farming provides over one quarter of those fish. There’s more variety too. Traditional species like carp and tilapia have been joined by high-value species such as swamp eel, crawfish and freshwater shrimp.
So how does it work?
Farmers dig trenches along the edges and across the rice field. They use the excavated soil to raise the banks around the rice field higher than normal paddies so that no water or fish can escape.
These fortified banks can support other crops, such as soybean, rapeseed or grasses which can be used as feed for the fish. A popular feed is azolla—an aquatic fern that grows very rapidly in watery soils—which also doubles up as an organic nitrogen fertilizer.
Don’t the fish eat the rice?The trenches are a refuge for the fish during the rice planting and harvesting seasons or when water levels are low, but they also keep the fish away from the rice seedlings when they are first planted.
At the start of the rice growing cycle the field is flooded. Farmers plant their rice and put juvenile fish into the trenches. Once the rice is established the fish are let into the rice fields where they grow until harvest time, when the water is drained and the fish collected.
These rice-fish culture system can produce from 300 to 900 kilograms of fish per hectare or 300 to 750 kilograms of prawns or crabs per hectare.
To stop them nibbling on the young rice plants, farmers feed the fish with green grasses and other feeds. But there are plenty more sources of fish food in the paddies: ones that the farmers are glad to get rid of.
Fish eat pests such as stemborer and leaffolder and so they reduce the need for pesticides. They also eat weeds that choke rice paddies and bacteria such as sheath blight disease and disease-infected leaves, thus reducing herbicide use.
Furthermore, by gobbling up all this biomass the fish are reducing methane emissions from decomposing vegetation by up to 30 percent compared to conventional rice farming.
And of course all this free food on offer means that the farmer has to spend less time and money growing or buying supplementary feed for the fish. Having eaten, the fish excrete rich organic fertilizer, which reduces the need for petrochemical-based fertilizers.
The fish don’t just protect rice health, but human health too. Fish eat mosquito larvae, and a study of one village in Guangxi province showed that as rice-fish cultivation increased malaria cases decreased.
The Communist Party backed rice-fish farming to make farmers richer. Beijing wanted to increase rural prosperity to keep people on the land and stem the destabilizing tide of urban migrants.
According to the FAO, it worked. “The income of some 2–3 million rural households has been significantly improved through rice-fish culture in China,” says Miao Weimin, who says the net income from rice-fish culture is 2,000 to 4,000 dollars per hectare.
Rice yields have improved as well, even though the space taken up by trenches for the fish can be up to 15 percent of the rice field.
Fish farmed rice is generally high quality rice too: organic rice that attracts a premium from discerning Chinese consumers. The farmer’s income can be increased by 2 to 4 times compared with sole crop farming.
What was a subsistence rice-fish culture has transformed into a green/organic food production system that enhances biodiversity and conserves a symbiotic rice-fish ecosystem.
Rice-fish farming faces challenges, however.
It relies on a good quality water supply and China is notorious for polluted waterways. China also faces a drought-prone future, particularly in the Yangtze River basin where much rice-fish farming is done.
And not many rice-fish farmers are following the environmentally friendly best practices described above. Better and more widespread education and training is required, as well as more stringent organic certification schemes.
That’s especially true if, as seems likely, rice-fish farming continues expanding. Currently, only 15 percent of the available area in China is used for rice-fish culture.
Looking further afield, the potential in the rest of Asia is enormous, with about 140 million hectares—nearly 90 percent of the world total—under rice cultivation. The Philippines, Bangladesh, India and Thailand are among the other Asian countries reviving or exploring rice-fish farming.
Their success or failure could have huge consequences for future food security, poverty alleviation, biodiversity preservation and human health.