soil Archives · The Natural Farmer

Land Use and Contaminants table excerpted by Jack Kittredge from the EPA publication “Brownfields and Urban Agriculture” and from “Using Historical Records to Assess Environmental Conditions at Community Gardens” by Robert Hersh and from “Toolbox for Sustainable City Living” by Scott Kellogg and Stacy Pettigrew

Overview

Across the country, communities are adopting the use of urban agriculture and community gardens for neighborhood revitalization. Sites ranging from former auto-manufacturers, industrial complexes, and whole neighborhoods, down to small individual lots, including commercial and residential areas, are being considered as potential spots for growing food.

Redeveloping any potentially contaminated urban property (often referred to as brownfields), brings up questions about the site’s environmental history and the risks posed by a proposed reuse. At this time there are no definitive standards for soil contaminant levels that are safe for food production. EPA has long-established soil screening levels for contaminated site cleanup, but these threshold-screening levels usually serve as a starting point for further property investigation and do not factor in plant uptake or bioavailability.
[Read more…] about Soils And Urban Agriculture:

Thlaspi caerulescens, or alpine pennycress, is a small, weedy member of the broccoli and cabbage family. It accumulates metals in its shoots at astoundingly high levels.

Phytoremediation is the use of green plants to remove pollutants from the environment or render them harmless. Current engineering-based technolo-gies used to clean up soils — like the removal of contaminated topsoil for storage in landfills — are very costly and dramatically disturb the landscape. But the “green” technology of using plants to take up heavy metals and radioisotopes can, in certain situations, provide a more economical approach and one that is less disruptive as well.

Certain plant species — known as metal hyperaccumulators — have the ability to extract elements from the soil and concentrate them in the easily har-vested plant stems, shoots, and leaves. These plant tissues can be collected, reduced in volume, and stored for later use. In addition, of course, while acting as vacuum cleaners these unique plants must also be able to tolerate and survive high levels of heavy metals in soils — like zinc, cadmium, and nickel.
[Read more…] about Phytoremediation: Using Plants to Clean Up Soils

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