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Fostering Sustainability and Innovation in Agriculture

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Urban Agriculture: Overcoming the Legacy of a City’s Past

August 3, 2012 |

City Farm Sustainable Urban Vegetable Farm Chicago

'City Farm,' an urban farm in Chicago

When most people think about cities, heavy industry, crowded housing and vacant lots are some of the images that can come to mind. Lush vegetable fields and orchards dripping with ripe fruit are rarely part of the picture. Yet with the proliferation of the local food movement and urban agriculture, this is exactly what is starting to pop up in urban environments all over the country.

“Cities, by their nature, are always changing and transitioning to something else,” says Catherine Tumber, author of the book Small, Gritty, and Green: the promise of America’s smaller industrial cities in a low-carbon world.  “What we now call ‘local food’ in the context of the city has a long history, from family garden plots and victory gardens to truck farming.”

These urban farms lost popularity in post-war society with the rise of suburbs and industrial agriculture. More recently, with the local food movement driving consumers to think about where their food comes from, more people are seeking out sources for fresh, healthy and affordable foods in their area. And what could be more local than the empty lot next door?

That is exactly what the founding members of City Slicker Farms were thinking when they converted their first empty lot in West Oakland to a garden.  “At the time,” says executive director Barbara Finnin, “it was difficult to find fresh healthy food.”  Residents were mired in a food desert, she said.

Rather than focusing on the challenges in their neighborhood such as freeways, poverty and pollution, City Slicker Farms decided to focus on the assets – people with an interest in farming and abundant vacant lots. This combination has allowed the group to grow over the past 10 years from a single plot to include several community market farms, a weekly farm stand and over 100 backyard gardens.

This was not an easy feat for the organization. There are many unique challenges that novice urban farmers face when converting vacant land into a farm, from low quality soil to lack of community support.

One of the primary concerns unique to urban locations, which is rarely an issue for more rural environs, is the legacy industry and residences have left behind. It is this legacy that determines whether the land can be used at all.

Location, location, location

Much like finding a good home, finding an ideal lot for an urban farm is all about location. But in this case, it’s not about how close the real estate is to public transportation or good schools; rather, it is the lot’s history that is the deciding factor.

In West Oakland, where City Slicker Farms is centered, there are ample industrial lots. “These are tempting because there are acres,” says Finnin. But, she adds that you have to look at the site history – was it a smelting factory or were they just canning fruit? The number and type of contaminants left behind from different manufacturing activities may not be known, and testing for industrial contaminants can be thousands of dollars.

As a result, City Slicker Farms focuses almost entirely on residential lots. “Typically when something is residentially zoned you are going to have [fewer] problems,” says Finnin. In these residential lots, the organization tests primarily for heavy metals, nutrients and soil pH for a total cost of about $10. In comparison to former industrial lots, the price difference is substantial.

Lead, having been used in house paints for decades, is one of the most widespread challenges to converting residential lots to usable land. There are many valid concerns that both farmers and consumers have with these soils. Is the soil safe to work in? Will the food be safe to eat? Fortunately, there are ways to mitigate lead contamination.

Phytoremediation vs. Human-remediation

Phytoremediation, the use of plants to remove or break down soil contaminants, has been touted as a natural, inexpensive solution to this very unnatural problem. The science behind phytoremediation is sound: certain plants, called hyper-accumulators, are resistant to heavy metals and can accumulate them in their biomass in high levels, removing the contaminants from the soil. These plants include many members of the Brassicaceae family (mustards and cabbages) (1) and sunflowers (2, 3).

The challenge with phytoremediation is that though hyper-accumulators are excellent at lead uptake, the lead itself is not always in a bioavailable form. Soil pH can actually change the form lead takes in the ground (4), and altering it can decrease plant absorption. It has been suggested that chelating agents like EDTA (ethylenediamine tetra acetic acid) could be used to help with greater accumulation when added to soils (1). But EDTA is not without its detractors, as it causes algae blooms in lakes and ponds making it not an ideal substance to spray in nature (5, 6).

Moreover, phytoremediation can have low success rates outside of a stable lab setting due to additional outside stressors such as compacted or low nutrient soils (7). There is also the problem of what to do with the plants after they accumulate lead – they are now contaminated, and you can’t just compost them.

The greatest challenge to phytoremediation, though, was laid out by Finnin: phytoremediation is inexpensive in terms of cost, but it is expensive in terms of time.

“I might be a little controversial with this,” she says, “but when you need to feed your family, phytoremediation might take 20 years. I think it needs to be done, but in urban agriculture, time is precious and the now is precious if you need to feed yourself. “

In the end, phytoremediation may be best suited for long-term plot rehabilitation, where there is time to restore the soil and a plan can be laid out for the safe disposal of contaminated biomass.

But, does this mean that land with some level of contamination is unusable?

Hardly. From building raised beds to mulching, City Slicker Farms has found ways to keep the people and vegetables above any mildly contaminated soils.

When lead levels are dangerously high, though, they step back and consider their options.  Capping off the soil and building garden beds on top of thick barrier sheets is possible, but high lead levels can be an opportunity for property-owners to finance large-scale remediation. Finnin reports that there are county-based programs in California that are designed to help property owners pay for lead remediation. Testing, though, is the first step of this process, to see how excessive the problem is.

Solutions for a fresher, healthier urban landscape

As with all agricultural practices, urban agriculture has its own host of unique challenges.

“What we are seeing is that [urban agriculture] is normalizing food again, especially for our young people who maybe have never seen something grow before,” Finnin says.

Catherine Tumber sees the local food movement and urban agriculture as something even more far-reaching. “I think this movement is of huge significance because it takes on at least five major issues that have bedeviled the postwar world: food security, economic inequality, environmental degradation (and now, climate change), the loss of craft skill, and overweening corporate power.”

“Remember, agriculture has always been a part of the cities,” Finnin says. “I’m excited about the future, because I think we are bringing it back!”

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Works Cited:

(1)  Ghosh M, Singh SP (2005) A review on phytoremediation of heavy metals and

Utilization of its byproducts.  Applied ecology and environmental research, 3(1): 1-18.  http://www.ecology.kee.hu/pdf/0301_001018.pdf

(2)    Gavrilescu D (2008) Equilibrium study of pb(ii) and hg(ii) sorption from aqueous solutions by moss peat.  Environmental Engineering and Management Journal, 7(5): 537-546. http://omicron.ch.tuiasi.ro/EEMJ/pdfs/vol7/no5/EEMJ_VOL%207_NR_5_2008.pdf#page=57

(3)   Boonyapookana B, Parkpian P, Techapinyawat S, DeLaune RD & A Jugsujinda (2005)  Phytoaccumulation of lead by sunflower (Helianthus annus), tobacco (Nicotiana tabacum), and vetiver (Vetiveria zizanioides) Journal of Environmental Science and Health, Part A: Toxic/Hazardous, 40(1):117-137. http://hero.epa.gov/index.cfm?action=reference.details&reference_id=82419

(4)  Xian X & G In Shokohifard (1989) Effect of pH on chemical forms and plant availability of cadmium, zinc, and lead in polluted soils.  Water, air, & soil pollution, 45(3-4):265-273.  http://www.springerlink.com/content/l16x23j4034p2n22/

(5)   Yuan Z & JM VanBriesen (2006) The formation of intermediates in EDTA and NTA  biodegradation. Environmental Engineering Science, 23(3): 533-544. http://online.liebertpub.com/doi/abs/10.1089/ees.2006.23.533

(6)  Lieberman DM (1995) Nutrient limitation in a southwestern desert reservoir: Eutrophication of Las Vegas Bay, Lake Mead, Nevada.   Publications (WR). Paper 29. http://digitalscholarship.unlv.edu/water_pubs/29

(7)  Gerhardt KE, Huang X-D, Glick BR & BM Greenberg (2009) Phytoremediation and rhizoremediation of organic soil contaminants: Potential and challenges.  Plant Science, 176: 20-30.  http://www.sciencedirect.com/science/article/pii/S0168945208002720

 

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