Apparently there has been a lot of clopyralid used in my area (eastern Washington) in the last few years. This stuff apparently has a half life of 11 months, but very tiny amounts (1 part per billion) can be devastating for legumes and other broadleaf crops.

I just found out today that a lot of composts made here in eastern washington are poisoning the plants they are supposed to be feeding because of traces of these herbicides. Yes, these herbicides will pass right through an animal.

I tried growing some fall peas in a field last year. They did very poorly. I was having a hard time figuring out why ... until now. I now suspect that there is some form of residual herbicide in that field.

I checked into getting the soil tested for these two long term herbicides: $125 for the clopyralid test and $175 for the picloram test. Ouch!

A less accurate test is to get some sterile potting soil and compare growing peas in the potting soil vs. growing peas in my soil. I'll be doing this experiment soon.

Of course, I have brought a mountain of manure onto my land last fall. I would have to guess that at least one of the loads contained one or the other of these herbicides. Testing compost/manure is even more expensive. I'll do the peas testing again.

Now for my question: Suppose I have these herbicides in my compost and soil. How do I get rid of it? I remember something a few years ago about how picloram is susceptable to ultra-violet rays. Anybody know what the kryptonite is for clopyralid?

-- Paul Wheaton (paul@javaranch.com), March 14, 2002

Answers

I'm currently an Environmetal specialist (employed by the State of Florida) looking at sites that deal with chemicals in their wastewater discharges to the environment... so here is some advice to keep in mind.

Anything you can do to decrease the half life would be good. Short of taking the time and expense to remove and burn (sterilize) the soil, I would try to expose it to sunlight as much as possible. Spread the compost as thin as possible. The increased exposure to UV will help and also the removal of moisture will help too. You may also want pile it up and get the internal temp way up through normal composting behavior... high temps will help to breakdown everything including unwanted chemicals. Lastly, you may try changing the pH of the compost through lime or cutting in high acidic litter like pine straw... this may speed the soil in its breakdown of the nasties.

All in all you may be stuck until it "naturally" degrades. Fortunatley the FDA and US Dept of AG have required that many of todays herbicides have a short half life... so if all else fails, hang in there, things should clear up over the next few years.

Otter

-- otter360 (kitchen@eng.fsu.edu), March 14, 2002.

I know that picloram (aka Tordon) has a half life of 17 YEARS! And I know that sunlight will shorten that. I also know that hot composting and stomach acids won't touch it. So I think what you are saying about spreading it thin will work for picloram.

But in today's rush of research on clopyralid I seem to recall that ultra-violet light doesn't do anything to it. And it goes through an animal unharmed. It does have a shorter half life (11 months). Since most of the reports are of commercial composting sites having traces of clopyralid making their compost unsellable, it makes me think that hot composting won't help.

I wish there was a site or report somewhere that would specifically say how to get rid of this stuff. If I can eliminate 90% of it by tilling once a week for ten weeks over the summer (thus exposing a wee bit more every week to ultra-violet light), it might be worth it.

In re-reading my original post, I think I'm babbling too much. Here's a summary:

Suppose a farmer is growing grass hay. The farmer might choose to fight weeds with an herbicide like clopyralid. The up-side is that the farmer might not need to spray again for years because this stuff lasts so long. The down side is that when the animals eat that hay, their manure will also contain the herbicide. The hay contains bits of the herbicide too. Suppose you make compost and use a little of this manure/hay/straw in your compost. You put your compost on your garden and everything in your garden dies. This is exactly what has happened to thousands of people in this region. There is a regional compost facility just down the road from me. Apparently they have mountains of compost tainted with this stuff and cannot sell it.

-- Paul Wheaton (paul@javaranch.com), March 14, 2002.

Hey Paul,

Yikes!!! If this is the case for you man I feel for you. I hate to say it, but I would invest in the tests...on your soil and on all of that compost you have on hand.

Now this might affect your fertilizer decisions. Perhaps you can use urea to produce hay that you can sell that will take with it part of the residual. I have a really hard time imagining tordon application on a meadow...my qestion is why why why. Anything that the railroad uses for the right of way I figure is about as bad as it can be. So will other grass crops give you what you need and take some of this away? Can you look into nondisclosure on your land. Seriously, if you expected to grow some broadleaf plants and expressed that and the seller did not tell you about herbicide use then....

Oscar

-- Oscar H. Will III (owill@mail.whittier.edu), March 14, 2002.

Paul, Just curious what part of Eastern Washington, I am in the Tri-Cities. Lots of farms around the county. Denise

-- Denise K. (Rabbitmom2@webbworks.com), March 14, 2002.

It's a possibility, of course, but it's not necessarily a certainty. Legumes won't necessarily do well on soil they haven't grown on before, or for a while, because they're missing the particular strain of inoculating bacteria (rhizobacteria?) that let them fix nitrogen. In your tests, it would be a good idea to inoculate some of the test plots/pots both with root-depth soil from a place where these crops have done well, and if you can get it, some of the straight commercial innoculant (talk to your produce store - they may be able to reach an agreement with someone who's buying it commercially to let you have a few grams). Also, again and as always, talk to your extension agents - you've already paid for them, they're trained and they know a lot - there's actually a fair chance they'll sympathise with where you're trying to go, but even if not they'll still know useful stuff.

-- Don Armstrong (darmst@yahoo.com.au), March 15, 2002.

Oscar, it's good to see you following all of my threads. :)

$700 for tests seems really painful. The other thing is that their tests cannot detect anything below 10ppb. And 1ppb is enough to hurt legumes.

I walked down to the field where I tried to grow peas last year. Although we still have some snow on the ground and the crocuses we planted last fall are just starting to emerge, there were some weeds getting started down in that field. Possibly purslane. Something I didn't recognize. But they were all broadleaf. However, since most herbicides emulate auxin, then this growth doesn't indicate that there isn't herbicides in that field.

Arrangements with the seller: The seller has already screwed us in a list of ways. We're trying to keep on good terms despite this because we think we could still get useful information from him. We've already talked about asking him about his herbicide habits and decided that he would probably just get really defensive.

Growing hay and carting it off is what has made this land so pitiful. Now that bringing material in from the outside is such a risk, it seems that the only way to improve the soil is to grow it here.

Denise, I'm a half hour north of Spokane. But my research indicates that this stuff has been used heavily in your area too.

Don, I've called the extension office and was permitted to talk to master gardeners. I'm a master gardener. The master gardener on the phone offered to send me pamphlets on soil testing outfits.

The extension agent that trained me to be a master gardener taught us to research, research, research and doubt everything you research! :) Then, test, test, test and prove your theories. So I'm still in the research phase.

I think that the extension office here does have a lot to offer, but I should go down there sometime and get the lay of the land to better understand how this particular extension office runs.

The important thing is that by posting this here I'm making others aware of these problems. It's still possible that I have nothing to worry about. Although my research makes me think there is a 90% chance that something in my imported compost materials has been tainted.

I'm going to go get some potting soil today and do some experimenting. In one pot I'll grow peas on plain potting soil. In another I'll grow peas in my soil. In another I'll grow peas in potting soil and compost. In some ways this test won't be as accurate as the $700 tests. In some ways this test will be better than the $700 tests.

-- Paul Wheaton (paul@javaranch.com), March 15, 2002.

Paul, Your right about it being used in this area. I have 3 acres left from my Grandfathers original farm so I pretty much know what was used here......DDT he thought it was wonderful stuff! After he passed on we found some in his shop. Took it to the Hazardous Waste dump, they said not unusual to find it on old farms! But for last 15 years minimal chemicals on this place! Denise

-- Denise K. (Rabbitmom2@webbworks.com), March 15, 2002.