I came across an interesting article that describes significant plant damage from manure contaminated with persistent broad-leaf herbicides such as aminopyralid.
This stuff is in hay, in straw, in cow manure, horse manure, goat manure and who knows where else. It’s not destroyed in a compost heap and it passes right through an animal’s digestive tract and into your garden fully capable of killing your carefully tended beds for YEARS.
Perhaps many of you are aware of this danger, but I thought this would be useful to post, as so many people mention that they use various sources for manure, hay, or straw.
It’s definitely worth mentioning and keeping in mind- Tordon is another that is very persistent and in some areas it’s used a great deal. It can keep you from growing anything except monocots for years.
Yes, this can be a big problem. I know one GH grower who used a load of manure compost a few years back, wiped out his tomato and pepper plants.
There are a few articles online about how to test for this. Basically plant peas in the questionable material and in a safe control. Then compare the plants after a couple of weeks. Something one can do at home at little or no expense.
Most of my almost 50 years of being a gardener and nurseryman have included scavenging for any horse manure source I could find. Tons of manure have passed from my trucks to plants I manage and I’ve never had an issue of herbicide contamination.
To say it can be a problem without quantifying it may be bad information if it makes you afraid to use what’s available for free and really needs to be put to use. At least the pea test is a way for those concerned to get peace of mind- but it can only be done with aged manure.
In the old gardenweb site there are dozens of posts about it. It is a fairly common occurrence in big box compost bags as well as local sellers of compost. Just compost made from CAFO manure and browns, retaining the herbicides, some of which are degraded only by sunlight. If you only have a garden, it is worth making your own with bags of leaves, chunks of soil, and kitchen scraps.
I had no idea the packaged manure could be contaminated with such stuff. I’m sure they use the herbicide here in Hawaii to some extent. I’ve heard a lot of the small sweet potato farmers in my area hire cheap foreign workers who have no regard for safe application or safe amounts of herbicides and pesticides.
I we have 14 cows and I’ve only ever collected their manure for use in the garden. Although I did get the chance to buy some wonderfully crumbly horse manure from a local farmer who goes to our church… I’m telling you, I never had better cherry tomatoes than the ones I grew with that!
Of course it really all depends on the source plants which the animals are eating. If they were grazing on a mixed field or ate alfalfa and grass hay, you are much less likely to see herbicide contamination. But it does and can happen.
Mrs. G, I think one has to be careful about being too broad with statements like that, becausefor just one example, plants, (such as with cedar and walnut and spotted knapweed) themselves put out herbicides but those chemicals aren’t poison to everything. Some poisons are very specific, and can even save lives: penicillin and other antibiotics are poison to germs.
I guess the short answer to your observation would be along the lines of “Well, plants and animals are different from one another and each other, and it depends”.
As we all know, the devil is in the details!
Having said all that, I think that it behooves us to be careful with all fire, in a manner of speaking, but to use thinks which work intelligently.
I hope things have been going well- always good to visit with you.
I saw a paper some time ago that showed gut inflammation in the animals from herbicides in the hay. For you the consumer it translates into more toxins deposited in animal fats via leaky gut, and generally the meat of a more inflamed animal. But animals generally survive. If you eat grass fed meat from a farmer, generally you don’t worry about this.
It very much depends on the area and what the farmer is trying to do. Out here we have weed-free certified hay; the folks growing that typically use herbicides to knock down the listed weeds (weed free doesn’t actually mean free of all weeds, just free of certain bad weeds on a list, when the inspector came by). It is a premium grass hay product. Many horse owners use weed-free grass hay because they can rest easy that they aren’t feeding noxious weeds to their prize animals, and often it is the highest quality they can get and their horses won’t be seeding noxious weeds in their pastures. [whether or not the herbicide are doing any damage to the critters is another question]
There can also be issues of herbicide carryover from use on previous crops. Those particular herbicides are quite potent and have a long life in the soil, plant residue and animal manure.
I’d expect how much of a risk a gardener faces with this problem is very region dependent. Do local practices make use of these herbicides on a regular basis.
But I suspect the problem raises the issue of what really is “organic”? Fed rules allow manure, without testing and without certification that the animal was fed organic feeds, to be used in a soil or compost mix and that mix can be labeled organic. No cheating involved, the rules allow this. I had a long talk about this with a local compost maker/seller who explained the details of his industry. I would hope that commercial producers are doing some tests, but who knows…
I can see the basis of the concern. It would be better if these anecdotal reports at least included lab reports ascertaining the presence of herbicides- but obviously, if my garden suffered like this from what seemed logically to be contaminated manure, I’d be all over this forum warning folks.
A study of a wide range of commercial manure composts by way of lab analysis would be more useful, of course, because lots of things happen in nature that are not the results of the most likely cause. However, the money is not there to explore the cases like those that horticulturists are reporting on in the articles you site.
I mentioned my own experiences with manures over the years. I’m interested if any members of the forum have had anything but positive experiences with manures properly applied.
Most of the manure I’ve obtained over the years has come from small horse farms where shaved wood and not hay is used for bedding, but they do serve the horses hay. I’ve also used the loose hay available for free at feed stores and the above mentioned horse farms and have never gotten anything but great results.
Why would hay contain herbicides? How does that happen?
But isn’t rye a form of grass? Most hay includes grasses around here. Maybe the issue is with alfalfa?
I used to use a lot of alfalfa shake as mulch for tender annuals and have since often suggested alfalfa cubes as an organic fertilizer. So far no herbicides detected.
Here we have a lot of fescue fields that are used for pasture and hay. Some people use a product called grazon that, as the name implies, you can let livestock graze on it after you apply it. It is a broad leaf spray and keeps weeds out of your pasture. When we grew alfalfa we did not apply herbicide, but we did have to spray insecticide to control weevils. Here alfalfa will slowly be taken over by fescue grass. I don’t know if you can spray a herbicide that would kill the grass and not harm the alfalfa.
