permaculture

[Jason Gerhardt <jasongerhardt@gmail.com>]

Hi Katy,
In the spirit of performing quality site analysis prior to purchasing or
forming a land use agreement I highly recommend getting the soil tested at
the various sites. You can affordably get soil tested from your in-state
land grant university (generally somewhere around $30 per sample), many
university labs will do heavy metal testing too, as well as pesticide and
herbicide, sometimes at a higher cost. Private labs like Timberleaf or Soil
Food Web Inc. can be helpful as well for more complicated testing such as
soil life and uncommon contaminants.

If you have heavy metals you are in store for serious remediation that
could mean soil removal. Petrochemical pollutants can generally be dealt
with using mycoremediation (oyster mushroom specifically).

Anna-Marie Carter in Watts Los Angeles has had to deal with seriously
contaminated sites for community gardens and has devised a system of raised
beds modeled after some of Cuba's urban garden designs.

The theory in permaculture circles has been that woody perennials will
filter out toxins via cambium layers and store toxins in the wood before
they make it to the fruit, but to my knowledge this is yet to be proven
scientifically.

Lastly, my default answer to questions about polluted soil has been that we
live in a toxic world, and the only way you will know what you can accept
and live with is to understand exactly what you are dealing with. This goes
back to solid site analysis. We have to draw the line somewhere, but in
general we are surrounded by toxins at all times (I am breathing in quite a
few as we speak I am sure). The only way to know where to draw the line is
to understand the site, history of use, and current soil conditions.

-- 
Jason Gerhardt
Designer and Educator