Researchers Float the Idea of Growing Crops on Lake Surfaces

Lake Nicaragua, where some of the prototypes are being tested. (Photo by jeffr_travel / CC BY-SA 2.0)

The next agricultural innovation is embodied by a raft of floating greens, gliding glibly across the surface of a lake. The design, pioneered by researchers in Costa Rica, is built with parts of the world like sub-Saharan Africa in mind, where there may be large lakes, but conversely, little rainfall for successful crop irrigation.

The researchers call their effort ‘aquatic agriculture’—the art of growing food crops on freshwater bodies—most commonly, lakes. They are currently testing the system on Lake Nicaragua in Nicaragua, and Lake Arenal in Costa Rica, showcasing different floating prototypes ranging from domed metal frameworks seeded with plants to floating tent structures that function like greenhouses. The team is motivated by the recognition that, increasingly, ensuring food security means moving beyond a fixation on land space alone.

“The key issue is water," said Ricardo Radulovich, one of the researchers, and a professor of water science at the University of Costa Rica, to the Guardian UK. “We have land, but water is the limiting element. You can have agriculture if you have water. If we use that lake surface to produce crops, aquatic plants, we won't waste water.”

The research team estimates that there are in excess of 300 million lakes around the world, and often, these occur in regions where rainfall is scarce. In some drier countries, rainfall is highly seasonal, with prolonged dry seasons that make crop farming unrewarding, if not improbable. And yet, some of these same regions harbor extensive lakes—such as Lake Victoria’s 26, 800 square mile stretch, bordered by Tanzania, Uganda, and Kenya.

Both natural and man-made lakes would be equally valuable for aquatic farming, the researchers say, since the technique they incorporate depends on the same simple mechanism: letting floating plants suck up lake water at an amount that wouldn’t exceed what naturally evaporates from the body of water itself.

The plants playing sailor on the current rafts are ‘watered’ as their roots hang through the bottom of the platform and sweep the water, or through ropes that are fixed to the bottom of plant pots, threaded through the platform, and left dangling in the lake, so transporting water up the filament to the plant.

The prototypes already carry bobbing cucumbers, melons, and heads of lettuce, the Guardian UK reports. The group’s project website even shows a miniature crop of tomato vines, waving in the breeze. Where water is contaminated, flowers could be grown instead of food.

The researchers suggest that other ‘crops’ aren’t beyond the scope of lake farming, either. “If people need it, and they do, the water environment must be used intelligently, and even changed, to an extent, without biological or environmental chaos,” Radulovich told the Guardian UK.

Lake space could be employed to farm fish, for instance, and even some river weeds like water hyacinth have potential, Radulovich reckons. This notorious stifler of the lake environment could be cultivated in a controlled way, and then processed to make animal feed, or even, at a stretch, a kind of nutritious flour for humans, he told the Guardian UK. 

“Seventy per cent of the world’s available water is used for irrigation,” Radulovich told SciDev.Net, flagging the intensity of the problem. Perhaps that problem will someday be met with an undulating sea of lettuce, tomatoes, and—who knows—a floating orchard or two.


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