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Plants growing without soil and crops buried underground – farmers are embracing exciting new approaches to produce food in a changing world.
Plant growers face huge challenges from a range of environmental and social factors. The changing climate threatens crops with either too much or too little water, while cities are competing with agriculture for the best farming land. As a result, farmers across the world have turned to innovative technologies to grow food crops in places you might not expect; underground, on city rooftops, in containers without any soil, and even in space!
Since 2000, the number and duration of droughts has increased, and in the United States alone, 186.4 billion acres of crops are affected.1 Drought affects the yields of crops differently, depending on their requirement for water,2 and is particularly harmful to thirsty plants such as salad vegetables and fruit. In the worst cases, crops completely fail to grow. Extremely dry conditions can also increase the risk of damage from pests and disease, which also lessens yields and crop quality.
But while drought undoubtably threatens global food security, it isn’t just changing weather patterns that are reducing the world’s croppable areas.
Early settlers made their homes where crops and animals flourished, which means that many of our biggest cities sit on top of the most productive land.3 Increasing urbanisation adds to the problem by taking adjacent land out of agricultural use, often for recreational activities.4
What cumulative effect does all this have? It means a rising global population is trying to produce adequate supplies of food from an available land mass that is shrinking as a result of climate change, degradation, urban sprawl, and other social factors.
Fortunately, there are people seeking solutions, such as Bristol-based aeroponics company LettUs Grow. Aeroponics is a way of growing plants without soil, replacing it with a mist of nutrients and water that is sprayed directly onto the roots.5 This allows farmers to produce salad crops in climate-controlled containers, which can be situated anywhere there is access to water, electricity, and internet.
Traditional aeroponic farms use nozzles to fire the nutrient solution at the roots under high pressure, but this can be unreliable because of issues with clogging and breaking, according to India Langley of LettUs Grow.
“We use ultrasonic technology – sounds above 20,000Hz – which shakes a very small layer of water and fertiliser to form a mist,” she says. “This travels to the plant root but allows them to have enough oxygen. All the water that is circulating is recaptured, and less water is used because the roots are not submerged.”
LettUs Grow’s technology is most commonly used to produce salads, herbs, and microgreens, to start off young trees, and to propagate crops such as coffee and bananas for research trials. The controlled climate allows plants to grow independently of day length and weather patterns.
“By growing salads all year you can reduce waste by not flying plants around the world,” says India. “Growing food more locally reduces food miles, helps food security and gives people access to food all year round. In our system there is no risk of fertiliser run-off and there is no need to use pesticides; everything is contained.”
Aeroponic technology has been around since the 1920s, and has been key to NASA’s plans for space exploration.6 Its aim is to provide fresh food for astronauts on long-term missions, but it also hopes to benefit from the other life-giving attribute of plants: their ability to produce oxygen.7 Growing plants in space is an extreme version of coping with resource loss and shows what can be achieved without soil and with limited inputs. If plants can be grown successfully without soil or gravity, and with only small amounts of water, it gives hope that Earth-bound growers can rise to the challenge of land degradation and climate change.
While there’s no commercial value to using aeroponics to grow cereal, owing to the scale required to produce enough useable crops, India sees the technology as being part of the bigger picture for food production.
“With agriculture, people often want to pitch one solution – but it has to be a patchwork of ideas,” she says. “We can grow things that work well inside, and grow things that work well outside. This will free up space to farm more regeneratively.”
Above our heads and beneath our feet, growers are adapting to the challenges of shrinking space by growing crops in unlikely places.
Growing Under Ground is using hydroponics and light technology to produce a year-round supply of salads and microgreens, 108ft (33m) below the streets of Clapham in south London.8 Meanwhile, high above cityscapes as diverse as Bangkok, Montreal, and Paris, farmers are taking unused rooftops and converting them to green spaces heaving with produce, herbs, and flowers.
Pete Ellis from Recover Green Roofs in Massachusetts works to design, build, and maintain rooftop farms. He says that they can reduce urban heat islands and noise pollution, and play a role in stormwater management.
“[Rooftop farms] allow us to increase food production not through adding more ground level production, or through continued reliance on extractive farming, but by leveraging the underutilised potential of the ubiquitous rooftop!” he says.
“They also use less water. Taking into consideration the reality that the world has a finite amount of farmable land, the option to create more production space within the built environment is a highly efficient land-use principle.”
For Pete the community benefits are exemplified by organisations such as Boston Medical Center’s Rooftop Farm, which grows plants and distributes them within the hospital, including through a prescription food pantry.
While modern rooftop farming embraces hydroponic technology and container systems, in its simplest form growing food on top of buildings has been practiced for millennia, with the oldest versions being found on the ziggurats of Mesopotamia.9 Rooftop farming can be done at any scale, from individuals growing vegetables for their own use, to organisations creating farms that use freight lifts and needing to consider whether the building can support the weight.
Although no single system can be considered a silver bullet solution to food security and climate change, adopting novel technologies can help grow plants efficiently in ways that reduce resource use and shorten supply chains. These innovative systems allow plants to be grown in more places, bringing not only food production but also green spaces into urban areas.
Aeroponics and rooftop farms can’t grow essential cereal crops on an economically viable scale, so they won’t replace the need to plant fields with wheat, barley, rice, and maize anytime soon – but for delicate salads and microgreens they can provide a constant environment in a rapidly changing world. There are many answers to the question of how to future-proof plant production. Some of them are already visible in cities around the world – you just might need to raise your eyes to the roof to see them.
This article was commissioned as part of 'Our Green Planet'. This is a digital initiative, from BBC Earth in association with The Moondance Foundation, to raise awareness for the beauty and fragility of our planet’s green ecosystems. Discover more here. #OurGreenPlanet.
Featured image © Sarote Pruksachat | Getty Images
1. National Integrated Drought Information System “Agriculture” 2. Ray 3. Du 4. Beckers 5. Science Direct “Aeroponics” 6. Green Matters “Why aeroponic farming is the agricultural wave of the future” 7. NASA “Progressive plant growing is a blooming business” 8. Growing Under Ground “Salad from where the sun doesn’t shine” 9. Turf Magazine “The history of rooftop gardens”