Before you think there’s already too much polyurethane foam in the world, check out what scientists are doing at the new Institute for Sustainable Food at the University of Sheffield in the UK.
The university says it is growing salad greens and tomatoes in an abandoned school converted into an urban farm, and the plants grow two to 10 times faster when they’re rooted in polyurethane foam rather than soil. Soils are increasingly compromised all over the world, according to a 2018 United Nations report, and finding a solution to damaged soils and decreased productivity is a food security priority.
“The world is facing a crisis of soil fertility. If we’re going to fix this, we need to do something radically different,” said institute director Duncan Cameron.“Urban farms that use foam instead of soil could take a lot of pressure off existing agricultural systems. And because this system is so efficient, it enables us to feed our growing population using fewer resources.”
Oddly, the Sheffield team first came across the idea while working at a Syrian refugee camp in Jordan. Chemistry professor Tony Ryan was at the Zaatari camp helping some of its 80,000 residents to reuse and recycle castoff bikes from Europe into useful products in the hot, dusty camp. One day he took a break to cool off in a camp warehouse, where he found used mattresses stacked to the ceiling.
At the same time, Ryan knew that Zaatari residents accustomed to fertile soils and farms in Syria’s Dara’a region couldn’t plant anything in the salty and lifeless land at the camp. They also didn’t have the water to spare on garden plants, since each of them was required to live on 37 liters of water per day.
That’s when the light bulb went off. Back in the UK, Ryan had been working with a doctoral student named Harry Wright who was experimenting with how polyurethane foams could be used as a soil-like medium. The foams are most commonly found in mattresses, and there they all were in the warehouse.
The United Nations refugee agency supplies them, but they can’t be reused by another camp resident, so they were pressed into service for gardening. The mattress foam supported the plants the way soil does, and water and nutrient solution stayed in the foam in ways that were impossible in Zaatari dirt. Ultimately, 200 residents were trained to use the system – nurturing food as well as restoring some well-being.
Wright learned from the Zaatari refugees too, and took the knowledge back to Sheffield. He developed special polyurethane foams that closely mimic soils and the nutrient solutions to feed plants in them. The urban farm supported by the Institute for Sustainable Food uses them and opened its doors to the public in May.
The Sheffield team says it has found success with the soil replacement and a new way to do hydroponics, but it continues to refine the project with an emphasis on making the foam biodegradable and reducing the energy inputs that go into making it. They’re also looking to do local job training, much as they did with the residents at Zaatari.
“For me, the beautiful part of the story is that the things we’ve learnt in a refugee camp have now been applied to Sheffield,” said Ryan.