The carbon footprint of homegrown food is complex. A study from the University of Michigan reveals that urban agriculture often has a higher carbon footprint than conventional agriculture. For example, the carbon emissions per serving of tomatoes grown in urban farms can be six times greater than those grown conventionally. This article explores the factors contributing to the carbon footprint of homegrown food and how urban farmers and gardeners can reduce it.
Here is a table that gives you quick comparison of carbon footprint between homegrown food vs conventional agriculture.
| Food Type | Urban Agriculture Carbon Footprint | Conventional Agriculture Carbon Footprint | Notes |
|---|---|---|---|
| Tomatoes | 2.5 – 4.2 kg CO2e (1.1 – 1.9 lb CO2e) | 1.1 – 2.0 kg CO2e (0.5 – 0.9 lb CO2e) | Urban-grown tomatoes have a higher footprint due to energy use in greenhouses. |
| Asparagus | 3.0 – 5.0 kg CO2e (1.4 – 2.3 lb CO2e) | 2.0 – 3.5 kg CO2e (0.9 – 1.6 lb CO2e) | Urban-grown asparagus can have a higher footprint due to air-freighting and energy use. |
| Lettuce | 1.5 – 3.0 kg CO2e (0.7 – 1.4 lb CO2e) | 0.8 – 1.5 kg CO2e (0.4 – 0.7 lb CO2e) | Conventional lettuce typically has a lower footprint due to more efficient farming practices. |
| Carrots | 1.2 – 2.5 kg CO2e (0.5 – 1.1 lb CO2e) | 0.7 – 1.3 kg CO2e (0.3 – 0.6 lb CO2e) | Conventional carrots often have a lower footprint due to less energy-intensive cultivation. |
| Cucumbers | 2.0 – 3.8 kg CO2e (0.9 – 1.7 lb CO2e) | 1.0 – 2.0 kg CO2e (0.5 – 0.9 lb CO2e) | Urban-grown cucumbers may have a higher footprint due to greenhouse requirements. |
| Strawberries | 3.5 – 6.0 kg CO2e (1.6 – 2.7 lb CO2e) | 2.0 – 3.5 kg CO2e (0.9 – 1.6 lb CO2e) | Higher footprint for urban strawberries due to energy use in urban environments. |
- Tomatoes: Urban-grown tomatoes can have a carbon footprint six times greater than conventionally grown ones due to greenhouse energy usage.
- Asparagus: Urban farming methods, especially those that involve air-freighting, result in a significantly higher carbon footprint compared to conventional methods.
- Lettuce and Carrots: Conventional agriculture often outperforms urban agriculture in terms of carbon emissions due to the efficiency of large-scale farming operations.
- Cucumbers and Strawberries: Urban farming typically results in higher carbon footprints due to the intensive use of energy and materials in urban settings.
Factors Contributing to the Carbon Footprint of Homegrown Food
- Materials Used in Urban Agriculture: The carbon footprint of food grown in urban settings is greatly influenced by the materials used to construct raised beds, greenhouses, and other infrastructure. A study shows that 73 urban farms and gardens in the Nature Cities dataset have carbon footprints times higher than conventional farms due to these materials.
- Energy Use: Urban farms typically only operate for a few years or a decade. This limited lifespan, combined with the energy required for lighting, heating, and cooling greenhouses, contributes to higher carbon dioxide emissions.
- Transportation: Though homegrown food is often praised for its lower transportation emissions, the impact can vary. Urban agriculture sites may still require energy-intensive transport methods for bringing in materials, water, and compost.
Interesting Facts about homegrown food
Urban farms and gardens overwhelmingly report improved mental health, diet, and social networks among participants. Despite the higher carbon footprint, the social benefits of urban farming may outcompete conventional agriculture.
Vegetables grown in urban farms are often more water-efficient and can use urban wastes as compost, reducing the need for synthetic fertilizers.
Studies from the University of Michigan and University of Kent suggest that certain practices in urban farming can lead to lower carbon footprints. For example, asparagus and other air-freighted crops can have a times greater carbon footprint when grown conventionally compared to urban agriculture.
Tips to Reduce the Carbon Footprint of Homegrown Food
- Conserve Carbon by Engaging in Sustainable Practices: Use locally-sourced, recycled materials for building garden beds and greenhouses.
- Reduce Inputs and Outputs on Urban Agriculture Sites: Focus on efficient water use and energy-saving techniques to lower the carbon footprint per serving of food.
- Support Sustainable Urban Farms: Choose urban farming projects that emphasize sustainability and use minimal synthetic inputs. Benjamin Goldstein from the School for Environment and Sustainability notes that some urban agriculture projects have outperformed conventional agriculture in reducing carbon emissions.
Effort in Reducing the Environmental Impact
Researchers at the University of Michigan and other institutions are exploring ways to reduce the carbon footprint of urban agriculture. By focusing on sustainable practices, urban farmers and gardeners can conserve resources and reduce their overall carbon footprint:
- Optimizing Energy Use: Studies are exploring the use of renewable energy sources like solar power to reduce reliance on fossil fuels. This includes powering greenhouses, irrigation systems, and other farm infrastructure with clean energy.
- Sustainable Materials: Research focuses on using recycled and locally sourced materials for constructing raised beds, greenhouses, and other urban farming structures. This helps lower the carbon footprint associated with the production and transportation of building materials.
- Improved Water Management: Innovations in water-saving technologies like rainwater harvesting and efficient irrigation systems are being tested to reduce water use and the associated carbon emissions in urban farms.
- Circular Economy Practices: The University of Michigan is investigating ways to integrate urban agriculture with waste management systems. For example, converting urban organic waste into compost to enrich soil can significantly reduce the need for synthetic fertilizers, thereby cutting down on carbon emissions.
- Community Engagement and Education: Efforts are being made to educate urban farmers and gardeners on best practices for reducing carbon emissions. This includes workshops on energy efficiency, sustainable crop selection, and techniques for minimizing resource use.
Comparison: Homegrown Food vs. Conventional Agriculture
While urban agriculture has higher carbon emissions per serving of certain crops, it also offers unique benefits. For instance, vegetables grown in urban settings can be fresher and more nutritious, though they may have a carbon footprint times larger than those grown on a conventional farm.
Detailed Comparison:
- Tomatoes grown in urban farms can have carbon footprints six times higher than those from conventional agriculture.
- Fruits and vegetables grown in urban settings often have a higher carbon footprint due to the inputs required for their production.
Final Thoughts
Urban agriculture provides an alternative to conventional farming with unique benefits and challenges. While urban farms are driven by community engagement and social benefits, they often have a higher carbon footprint due to the materials used and the energy required for their operation. However, studies show that with the right practices, urban agriculture can significantly reduce its carbon footprint and offer a more sustainable way to produce food in cities.
Sources:
- University of Michigan SEAS – Urban Agriculture and Carbon Footprint
- Nature Cities – Carbon Footprint of Urban Agriculture
- Phys.org – Climate Impacts of Urban Farming
