As the population of cities grows, urban agriculture is increasingly seen as an important local food source and a way to address inequitable access to food. However, little is known about the productivity of urban agriculture compared to conventional subsistence agriculture. Urban gardeners and hydroponics can match and sometimes even exceed crop yields from rural farms, according to a new study by Lancaster University.
Scientists have compiled studies on urban agriculture from 53 countries to clarify which crops grow well in cities, which cultivation methods are most efficient, and what types of urban spaces can be used for cultivation. The analysis revealed that urban yields for certain crops – such as cucumbers, lettuce or tubers – are two to four times higher than in the case of conventional agriculture.
While most studies of urban agriculture have focused on green spaces, such as private and community gardens, parks, or open-field cultivation operations, this study also considered so-called “grey spaces”. — including rooftops or building facades — while looking at a variety of crops grown in soils versus hydroponics, horizontal versus vertical farming, and natural versus controlled conditions.
“Surprisingly, there were few differences between overall yields in indoor and outdoor green spaces, but there were clear differences in the suitability of crop types to different gray spaces,” the lead author reported. of the study Florian Payen, environmental scientist at Lancaster.
While crops such as lettuce, broccoli, or kale are more naturally suited to being grown vertically in indoor spaces, other crops, such as aquatic vegetables and leafy greens, have performed better in hydroponic environments. Since crops grown in fully controlled environments allow harvests to occur more times per year than those grown outdoors, such methods can lead to higher annual yields.
Current estimates suggest that between 5 and 10% of pulses, vegetables and tubers are grown in urban areas, and that between 15 and 20% of the world’s food is produced in cities. Once more data is collected, in-depth studies estimating the potential of cities to meet future food demands will be possible.
“As we engaged and discussed with different stakeholders, such as government agencies and local councils, we realized that the lack of robust and comprehensive data on urban agricultural yields was preventing them from moving forward. forward and to support the development and implementation of urban food culture,” Payen explained. “We need to realistically understand how much this form of cultivation could contribute to food security to help make the business case for it.”
Further research is also needed to assess how food grown in cities might be impacted by pollution and to better understand whether growing food in cities has a smaller or larger carbon footprint than conventional agriculture.
The study is published in the journal Earth’s future.
By Andrei Ionescu, Terre.com Personal editor