Breakthrough Could Turn City Rooftops Into Bumper Vegetable Gardens
Scientists find that expelled air from ventilation systems can make corn and spinach grow taller and larger, recycling CO2-rich indoor air to fertilize edible plants.
Science Blog
Oct 24, 2022
Excerpt:
“We wanted to test whether there is an untapped resource inside buildings that could be used to make plants grow larger in rooftop farms,” said Buckley, whose team named their experimental garden BIG GRO and published their work today in Frontiers in Sustainable Food Systems. “Creating more favorable conditions that increase growth could help make rooftop farms more successful and therefore more viable options for installation on buildings.”
Corn and spinach were chosen because they are common edible plants and because they use different pathways to photosynthesize, one of which (C3, used by spinach but not corn) is more sensitive to elevated CO2 levels and should benefit more from the exhaust vents’ CO2 content. Corn acted as a control to see how other aspects of placement close to the exhaust vents — for example, the higher temperature relative to the time of year when the experiments were conducted — affected plant growth.
The rooftop garden also featured controls that were fanned by large fans without any exhaust air, in case air movement from the vents was a contributing factor. The concentrations of CO2 in the classrooms inside the building and in the garden were regularly measured to establish how much extra CO2 was reaching the plants.
“With the CO2 measurements, high concentrations were found both inside classrooms and at rooftop exhaust vents when people were in the building,” Buckley said. “CO2 levels averaged above 1000 parts per million — the recommended limit — in classrooms and above 800ppm — high enough to increase growth in plants — at the rooftop exhaust vents.”
