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hubie [soylentnews.org] writes:

The combination of green and "gray" spaces in cities, along with the variability of growing modes, means some city crops — like cucumbers, potatoes and lettuces — yield at least twice as much as their rural counterparts [agu.org]:

As urban populations boom, urban agriculture is increasingly looked to as a local food source and a way to help combat inequitable food access. But little is known about how productive urban agriculture is compared to conventional, rural farming. A new study digs in, finding urban gardeners and hydroponics can meet and sometimes exceed the yields of rural farms.

"Despite its growing popularity, there's still quite a lot we don't know about urban agriculture, like whether the yields are similar to conventional agriculture, or even what crops are commonly grown," says Florian Payen, an environmental scientist at Lancaster University and lead author of the study, published today in AGU's journal Earth's Future.

The new study compiles studies on urban agriculture from 53 countries to find out which crops grow well in cities, what growing methods are most effective, and what spaces can be utilized for growing. [...]

"Surprisingly, there were few differences between overall yields in indoor spaces and outdoor green spaces, but there were clear differences in the suitability of crop types to different gray spaces," Payen says. Certain crops like lettuces, kale and broccoli are more naturally suited to be grown vertically in indoor spaces than others. "You can't exactly stack up apple trees in a five- or ten-layer high growth chamber," he says, "though we did find one study that managed to grow wheat stacked up like that."

Other crops, like watery vegetables (e.g., tomatoes) and leafy greens, performed well in hydroponic environments. And crops grown in fully controlled environments can be grown throughout the year, allowing harvests to happen more times per year than in open-air environments, which leads to higher annual yields. But scientists will need to keep studying these systems to plan cost-effective agriculture solutions.

[...] It remains to be seen whether growing food in cities has a smaller or larger overall carbon footprint than conventional agriculture; the answer likely varies. Researchers are also studying how foods grown in cities might be impacted by pollution. And some crops included in the study's literature review lacked the numbers to be included in statistical analyses, pointing to a need for more research on urban crops like fruits and cereals.

Journal Reference:
Florian Thomas Payen, Daniel L. Evans, Natalia Falagán, et al., How Much Food Can We Grow in Urban Areas? Food Production and Crop Yields of Urban Agriculture: A Meta-Analysis [open], Earth's Future, 2022. DOI: 10.1029/2022EF002748 [doi.org]

Original Submission