Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
February, 2012
Regional Report

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Gardening in raised beds is a good solution if you have concerns about lead contamination in your soil.

Getting the Lead Out

When my husband was eight or nine years old in the late nineteen fifties, one of his favorite toys was a small lead smelter with which he could cast toy soldiers. He fondly recalls going to the plumbing store with his mother to purchase large chunks of lead to melt down. (I am not making this up!) He would then pour the hot molten metal into molds to raise a new set of troops.

Besides illustrating how attitudes toward child safety have changed a wee bit since then, it also shows how our concern over the hazard lead poses has changed too. Imagine giving a child a chunk of lead to play with today! We now recognize that lead, whether in plumbing materials, paint, or as a component of gasoline, presents a danger to health, especially to the developing brains and bodies of children. (I have been known to tell my husband jokingly that his lead-laden childhood explains a lot!)

Lead can also be found sometimes as a contaminant in soil. While we tend to think of this as primarily a problem in urban areas, the fact is that the wide use of lead in paint, as a gasoline additive, and in some pesticides in the past make its presence in soil a possibility in suburban and even rural areas as well. So I think it's a good idea, no matter where you garden, to have your soil tested for lead contamination unless you are sure of the past history of your garden plot. Testing is usually offered by state soil testing labs for a reasonable fee. For example, in Vermont, the University of Vermont's Agricultural and Environmental Testing Laboratory offers testing for heavy metals (lead, nickel, cadmium, and chromium) as a $10 add-on to it's standard $14.00 soil test.

If lead levels are not elevated in your garden's soil, then you get peace of mind. But if the test shows they are high enough to be of concern, don't despair! There are still things you can do to keep gardening safely. Of course, the risk varies with the level of contamination, and if your soil test reveals high levels, be sure to get expert advice from your local Cooperative Extension Service and Health Department on how best to deal with the problem. But there are some general strategies you can use to minimize your risk of exposure.

It's important to realize that the main route of exposure to lead in soil is not due to the uptake and accumulation of this element in the crops you're growing. Instead, it's the soil and dust you and your plants come into contact with as you work in the garden that presents the greatest threat. Washing your hands well after gardening and before eating and laundering dirty gardening clothes separately from the rest of the family wash are easy ways to reduce the possibility of exposure.

Another strategy is to locate your garden away from the foundation of any buildings old enough to have had lead-based paint used on their exteriors. (Such paint was not banned until 1978.) Spreading mulch over the soil minimizes direct contact with the soil and reduces risk. Raised beds filled with fresh soil or container planting are good alternatives when there is concern about contamination of the native soil in your garden.

Adding organic matter like compost to the soil and keeping the soil pH 6.5 or above helps to limit the amount of contaminants that plants take up by making metals less mobile in the soil. Fruiting crops like tomatoes, beans, and peppers take up less lead in the plant parts we consume than root crops and leafy crops.

And of course wash all vegetables well before eating. Peeling root crops and discarding the lower leaves of leafy crops like lettuce also reduces exposure if there is lead in the soil.

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