Herbicide Carryover Creates Toxic Compost: A Speech From the 2013 Rachel Carson Council Open House

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Photo By Barbara Pleasant
Outside of the Rachel Carson House, a National Historic Landmark where Carson wrote her classic work, and where the Rachel Carson Council holds an annual open house.

One of MOTHER EARTH NEWS’ contributing editors, expert gardener Barbara Pleasant, recently gave a speech at the Rachel Carson Council Open House in Silver Spring, Md.  The Rachel Carson Open House is an annual event that is free to the public. It takes place at the Maryland home, registered as a National Historic Landmark, where Rachel Carson wrote Silent Spring, the book that launched the modern environmental movement. This is the full text of Pleasant’s talk on the issue of herbicide carryover creating toxic compost.

Being here today is a tremendous honor for me, and for the team at MOTHER EARTH NEWS. We work hard providing information to help people live more self-sufficient lives. Part of that involves showing people how to recycle their kitchen and garden waste into compost, which in turn enriches their gardens. Since 2009, we have been reporting on herbicide contamination threats to composting, starting just after the Rachel Carson Council raised a red flag on this important issue. Like the Rachel Carson Council, we are extremely concerned about “killer compost.”

But first, what is compost? Compost is what you get when materials that were once alive and are now dead are managed so that they rot into dark, crumbly organic matter that enriches soil and helps plants grow. Leaves, grass clippings, pulled weeds, and quite a lot of kitchen waste can be combined into a simple, self-perpetuating compost pile. There are perhaps 100 ways to compost, and nature is always on your side, because dead things naturally rot. Composting is the preferred way to recycle yard and kitchen wastes because the materials never leave the property.  

We gardeners make compost for the end result. It’s a scientific fact that soils amended with compost support healthier, more disease-resistant plants — so we can never get enough compost.

Towns and cities make compost to reduce how much garbage they must handle. Half of the states require that yard waste like leaves and grass clippings be diverted to a composting facility rather than being sent to landfills. In addition to saving landfill space, taking out the compostables reduces methane and other greenhouse gases produced by rotting garbage.

This year, more than 150 U.S. communities have started including compostable materials in their curbside recycling programs, usually by providing color-coded brown bins. The biggest curbside composting program in the country, in San Francisco, now collects 600 tons a day of compostable materials.

In other communities, home composting is encouraged and supported, but gardeners need no persuasion to make compost. The most encouraging statistic I know is this one: 90 percent of gardeners who start composting keep composting. It becomes a lifetime habit.

How Gardeners Think

Growing a garden, for reasons I really can’t explain, is an intensely emotional process. The satisfaction I get from harvesting a perfect potato goes far beyond what the potato is worth in dollars and cents. I take more pride in growing, harvesting, preserving and serving my fruits and vegetables than anything else I do in life. From spring to fall, it is my life. Every day there is something new to discover — things that make you want to put on your mud shoes and go out to see what’s happening. There is nothing quite like being part of the process of helping a single seed turn into a platter covered with tomatoes. It feels like magic.

So, I want you to imagine some gardeners who have done everything right — enriched their soil, given seedlings excellent care, and planted them at the right time. Maybe they have a small market garden, with a few acres that are certified organic — your favorite vendors at the farmers market. Maybe they are hard-working city people who have a plot in a community garden where they spend every Saturday.

Now the killer compost nightmare begins. The peas grow 8 inches tall and start withering. The tomatoes and peppers no sooner hit the soil than the leaves start curling up and dying. The spinach looks like it has been blasted with a blowtorch.

It is the gardener’s tendency to think they did something wrong. They think:

Maybe I didn’t mix in the fertilizer well enough and the roots were damaged.

Maybe the soil temperature is lower than I thought.

Maybe the plants have a virus.

But the trouble is likely due to something else — troubles that have arisen from the same forces that caused Rachel Carson to write Silent Spring in this very house. In Carson’s day, insecticides that killed insects and then entered the food chain to kill birds and fish were among the most alarming threats to the environment, and this problem is with us today in forms like imidacloprid, the systemic insecticide that has been linked with bee colony collapse disorder.

Persistent Herbicides Are to Blame

But in home gardens and on organic farms, it is not insecticides but persistent herbicides, or weed killers, that are giving us fits. Several new herbicides developed by Dow and Syngenta have become the weed killers that keep on killing. They persist in soil, hay, animal manure, and in the tissues of crops grown in treated soil. Worst of all, three chemicals now in common use — cloypyralid, aminopyralid and picloram — persist in compost. It takes only a little to turn good compost into killer compost.

To back up a bit, 25 states have mandatory composting of organic materials. These chemicals are coming in, they must come in, and the composting facilities have no way of knowing how or where they are coming from. 

Imprelis, a fourth herbicide (this one developed by DuPont), was pulled from shelves after it killed Norfolk pines and other beautiful landscape trees the first year it hit the market. It was supposed to keep dandelions out of bluegrass. Even though we don’t have to worry about Imprelis for a while, it’s a clear example of The Problem with persistent herbicides — horribly inadequate testing. In the cases of all of these herbicides, EPA approval was given despite the fact that no testing procedures existed to monitor residues in soil or plant material at the time.  

Last year a team of scientists did publish a procedure for determining residues of clopyralid and aminopyralid in fruits and vegetables, so now we can peek into the dark, at the monster lurking in the closet, which is the contamination of our food supply with the same persistent herbicides that contaminate compost.

The next frontier in the fight to protect the world’s environment will not be about what insects or birds or fish are eating, but about what you are eating, what’s on your plate, what’s going into your bodies. These herbicides have been used on some food crops for almost a decade, but until last year, lab protocols did not exist to test for residues in food. The chemical companies were the only ones who knew how to test for residues in compost, and pyralid testing of foods, well, why bother? After all, this was a weed killer, not an insecticide.

What was the EPA thinking? There are a lot of theories, most of them political, but the EPA has had a lot of chances to set things right.

The first reported problems with these chemicals occurred in the Pacific Northwest in the late 1990s, when toxic compost was linked to a new herbicide being used on lawns. This was clopyralid. The label was changed, with more restrictions, and the issue went to sleep for almost 10 years. Then, in 2008, thousands of gardens in the UK were damaged by aminopyralid after the herbicide persisted in horse manure. The Rachel Carson Council called for immediate action. At MOTHER EARTH NEWS, we picked up the torch and coined the phrase “killer compost,” also asking for an immediate suspension of aminopyralid’s registration.

Since 2009, we have run several stories on killer compost, the most recent one this spring following the shut-down of Green Mountain Composting facilities in Vermont and New York due to herbicide contamination. When clopyralid and picloram were first detected in the compost, it was assumed that the chemicals came in on grass clippings and horse manure, their historical modes of entry. But further and subsequent testing has revealed extremely high levels of clopyralid in horse and cattle feed. Corn. Oats. Food.

Composting in 2013 and Beyond

I have questions. Since the beginning, owners of grazing animals have been reassured that eating hay laced with aminopyralid and other pyralid pesticides would not harm their animals, but this is more hype than fact. Nothing is known about the long term effects of ingestion of persistent herbicides by grazing animals. Again, no testing. If you buy commercial grain-fed beef, this may be what you are eating.

Meanwhile, there is a disturbing new study from Alaska showing that potatoes can take up and concentrate aminopyralid in their tubers. So, you could grow wheat and treat it with Merit or Stinger, and the next year grow potatoes there and have high aminopyralid residues in the crop. No testing required. But do you want to eat those spuds?    

Organic folks like me often think, “So what? I’ll grow my own.” But can we? We have no choice but to try. The chemical companies have made my life harder, and added to my labors, as they have used my world for their chemistry experiments.

  • No more hay for mulching. I cut my own grass clippings instead. There are so many herbicides on wheat straw that it is considered toxic by organic growers.
  • No more manure from my friend’s horses. Although the pasture has never been treated with anything, the horses eat feed, now a known source of killer compost.
  • No more commercially-produced compost, even from my local compost producer, because it’s not worth the risk. If I were certified organic, one mistake could make me lose certification for three years.

But even with these precautions, I am haunted. If these and other chemicals are in horse feed, they are probably in my chicken feed, too. In my free-range eggs? There may be no escape.

I hope things are ready to turn around. Like the Rachel Carson Council and MOTHER EARTH NEWS, the Composting Council has asked the EPA to “revoke the registration of all herbicides known to persist in compost at levels that are toxic to plants, and require that these products be removed from the market.”Sounds great to me, but we need to start talking about food crops, too. Chemical companies should not be able to even think about applying for registration of new herbicides and pesticides, or maintain registration of old ones, unless publically accessible methods exist for residue testing in a range of environments and on a broad range of crops.

The old way of doing things — “This works really well, but we don’t know what happens next” — is not good enough. At MOTHER EARTH NEWS, we will keep banging the drum as loudly as we can, and we know the Rachel Carson Council will do the same.