Guide to Vegetable Garden Safety

by Joseph H. Rule, Ph.D, Professor of Biogeochemistry

This is intended to be a short commentary and guide to growing vegetable crops in soil that may have been impacted by contamination. It is not intended to replace thorough testing for soil contaminants. An important resource is the LSU Ag Center, whose web address is: http://www.lsuagcenter.com/en/lawn_garden/

From this page you can access the Soil Testing and Plant Analysis Lab page: http://www.lsuagcenter.com/en/our_offices/departments/Agronomy_Environmental_Management/soil_testing_lab/

Testing by the LSU Ag Center around New Orleans did not find any elevated levels of heavy metals or salinity in the tested soils. However, in order to ensure that your specific soil has not been impacted, you may choose to have the soil tested. There are several soil tests available including a Salinity Soil Test for Storm Impact.

Some of the steps that the homeowner may take to address soil contamination concerns are as follows.

Assess the amount of newly deposited soil; if concerned, scrape the soil from the garden area and remove it from the site if possible. If not, place the soil on plastic or other impermeable barrier and securely cover with similar material to prevent rain water from reaching the material.

Most soil contaminants will bind tightly to the soil particles and will move very slowly to the soil below.

Examine the earthworms and other soil animals, if present to ensure that they appear as healthy and viable as before the flooding.

The addition of organic matter (peat, biosolids, compost, etc.) is always a good idea and these materials will bind a large number of contaminants and reduce their uptake by plants.

The addition of lime will also render many metal contaminants unavailable to plants. Most Louisana soils are acid but it’s always a good idea to have the soil tested before adding lime to prevent over-liming (which will also cause plant growth problems).

Examine any plants growing in the area to assess their degree of health. Carefully examine the plants and vegetables as the garden develops and mentally compare them with crops from previous years. This is important; maybe the tomatoes didn’t look so great last year either.

You can always use container gardening for a year if you can obtain a sufficient quantity of fresh, uncontaminated soil. Be careful if obtaining bulk soil to ensure the origin is from an uncontaminated area.