Headlines about Urban Gardening Carbon Footprint miss main points of study

 

Gardening is not immune to fads. Raised bed gardens, synthetic soils, specialized trellises, vegetables that look cool but are not part of the native cuisine and so on.

Most of the climate impacts at urban farms are driven by the materials used to construct them — the infrastructure,” Goldstein said. “These farms typically only operate for a few years or a decade     Source

Commercial agriculture does not invest in foot-paths

Note that woodchips used to construct pathways would be considered "Infrastructure" while woodchips used for mulch would be considered "Supplies".

Strawbale gardening is popular with senior citizens who might have bad backs or knees. The bales of straw are considered "Infrastructure" and are typically replaced every year.

Urban gardens are almost always fenced off. Fence is infrastructure. Smaller gardens have more length-of-fence/area than larger gardens. Fencing materials have a carbon equivalent.

As a side-note, fences are useful for "vertical gardening" where sunlight that would fall on grassed area outside of the garden can be harvested. Pole beans, snap peas, cucumbers, winter squash, indeterminate tomatoes are just some of the vining plants that can be used this way.

A point that was missed by the article was carbon-avoidance. Did the fact that the gardener had everything she needed to make a salad growing in the garden result in the avoidance of six-miles of urban driving to purchase three green-onions? Did the stress-reducing properties of being in the sun playing in the dirt result in the avoidance of a trip to the shrink or to the bar that night?

The recommendations of the study (slightly filtered by me, ERJ):

Encourage the longevity of the garden (PRIME FINDING OF THE STUDY!!!)

Per-year Carbon footprint shrinks the longer the gardens are sustained because CE is dominated by infrastructure. Take steps to ensure longevity. Sometimes replacing worn-out, less-durable bits like garden hose means the gardeners do not abandon the more durable bits that are still functioning.

Recycle urban wastes

Examples include leaves from nearby trees for mulch, locally generated woodchips, waste-paper, saplings for tomato-stakes, gray-water for irrigation.

That would require a change in mindset of many of the urban gardeners who want everything to show up in plastic bags from the big-box store, just like the suburban gardeners buy. They often believe that being asked to use local products is a sign of "disrespect".

Encourage "high-level social benefits"

Cost of a "therapy" session with a trained, mental-health professional runs between $100 and $250 in the Untied States. Keeping "book" on the emotional-health benefits of an urban garden means that the "carbon costs" can be compared to the combined carbon-costs of commercial agriculture AND the mental-health industry.