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Toxic Harvest: the Case for Raised-Beds in Urban Agriculture

It’s hard to overstate the importance of good soil.  Tomatoes with rotten bottoms, plants with yellow leaves, and stunted growth are all symptoms of nutrient-deprived soil.  Fortunately, with the right organic fertilizers these problems can be easily remedied.  What is more troublesome are the soil problems that don’t affect the appearance of the plant.  Some chemicals can accumulate inside plants without any visible side effects, posing a health risk to uninformed urban farmers.


One of the best parts about urban farming is taking something that used to be hideous – an old parking lot, a yard adjacent to an abandoned factory – and turning it into a flourishing agricultural space.  Unfortunately, after years of industrial production, most urban soil is full of contaminants that are taken in through the roots of plants.  In-ground urban farms can still have a bountiful harvest, but chances are the fruits and vegetables will be saturated with unsafe levels of lead or other industry biproducts.

So what’s an urban farmer to do? The best first step is to get the soil tested by a nearby college or university.  Massachusetts residents can send soil samples to UMass Amherst, which charges $15 per sample.  Soil tests are extremely valuable, because they detail the current chemical make-up of the soil and then offer suggestions on how it might best be altered to help plants grow to their full potential.  

In terms of lead levels, here’s all you need to know:

0 – 299 ppm: Safe for all plants.

300 – 999 ppm: Avoid leafy greens and root vegetables. Not recommended for pregnant women and children under 6.

1000 – 2000 ppm: Unsafe. Edible plants should not be grown.

If, as is common in urban areas, your soil comes back with medium or high lead levels don’t despair – build raised beds, or start a rooftop farm! Soil brought in from other places will be free from industrial contaminants, so you can grow your own food without fear of lead poisoning.


Even though most urban soil is contaminated with lead and should not be grown in, the soil is not ruined forever.  Some plants, such as sunflowers, can be used to extract lead from the soil.  The only problem with this is that it typically takes between 5 and 10 years before the soil is ready to be used for farming again, which is longer than most people want to wait before growing their own food.  One solution could be to put raised beds on some of the soil and sunflowers on the other open spaces, which would allow for current harvests while restoring the earth for future growing.  

Want to learn more? Check out The Urban Bounty: How to Grow Fresh Food, Anywhere.

Local restaurants often make ideal locations for growing their own herbs and select crops to supply their chef with ultra-fresh produce, as lush gardens in boxes lining an ourdoor patio, on a rooftop, or in an ally or parking lot can beautify an urban space adding curb appeal. Own or chef at a local restaurant? Request an on-site consultation to evaluate your available space.

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