Urban agriculture, the practice of cultivating crops and livestock in urban areas, is becoming popular across the world. It’s also often believed to be a way to make food systems sustainable.
However, a new study shows that fruits and vegetables grown in urban gardens could have a significantly higher carbon footprint compared to when they are grown in conventional farms.
For the study, researchers from Michigan University collected data from farmers and gardeners at 73 urban agriculture sites in France, Germany, Poland, the UK and the US. They tracked greenhouse gas emissions from farm infrastructure, supplies and irrigation water using daily diary entries made during the 2019 season, a Press Trust of India report says. The findings of the largest study of its kind showed that the carbon footprint of the produce grown in urban gardens in Europe and the US is six times larger on average.
The findings, published recently in the journal Nature Cities, showed that on average, food grown in city gardens emitted 0.42 kilograms of carbon dioxide equivalent per serving of food, compared to 0.07 kilograms of carbon dioxide equivalent per serving of food from conventional farms, a press statement from the university explained.
Most of the climate impacts at urban farms are driven by the materials used to construct them, the study’s co-lead author Benjamin Goldstein said in the statement. He added: “These farms typically only operate for a few years or a decade, so the greenhouse gases used to produce those materials are not used effectively. Conventional agriculture, on the other hand, is very efficient and hard to compete with.”
For instance, conventional farms often grow a single crop with the help of pesticides and fertilizers, which leads to larger harvests and a reduced carbon footprint when compared to urban farms, he added.
However, there are some ways to reduce urban farming’s carbon emissions. One, extending the use of urban agricultural materials and structures by using raised beds and composting sets, which could reduce the environmental impact. According to the researchers, a raised bed used for 20 years will have a quarter of the impact of a bed used for just five years, the statement explained.
Another way is to repurpose used materials such as construction debris for urban agriculture. This also includes using rainwater for irrigation.