Uncomposted horse manure for garlic and shallots?

Hey, quick question.

The truckload of horse manure I picked up this morning was not as aged as it was advertised to be. (It was, however, as free as it was advertised to be. =) How big a chance am I taking by just tilling it into the field where I want to do garlic and shallots? Should I bioassay first to make sure it's free of herbicides, or does that danger get overhyped?

Thanks in advance!

Hi, Charles

I don't have any experience with uncomposted horse manure so my suggestion would be to compost it and use it at a later date.

Maybe someone with experience will chime in.

If it’s partially composted, you could probably use a little now.

Ask the horse owner about their source for hay. The herbicide problem is not overhyped. The herbicide is Grazon (and other brand names), and IIRC the generic name is amipyralids.

Hay farmers who produce specifically for horses use this stuff to make hay without broadleaf weeds. It is excreted in the manure, and remains there after composting.

It’s safe for grasses, but will kill nearly all your vegetables. Google the photos. It’s horrifying.

Anne Pratt wrote:Ask the horse owner about their source for hay. The herbicide problem is not overhyped. The herbicide is Grazon (and other brand names), and IIRC the generic name is amipyralids.

Hay farmers who produce specifically for horses use this stuff to make hay without broadleaf weeds. It is excreted in the manure, and remains there after composting.

It’s safe for grasses, but will kill nearly all your vegetables. Google the photos. It’s horrifying.

Yes. This.

I would never use horse manure without testing it first by growing a vulnerable plant using manure tea, compared to a control plant... unless I had exceedingly great confidence in the source...

Just to give you a frame of reference, there was a widespread distribution of mislabeled compost here in central NC this spring.  The compost had been made with an herbicide-tainted hay stock that had been labeled as organic.  This was one component of many in these tons and tons of compost, which were sold to garden supply centers, and they in turn mixed that compost into their own diluted mixtures.

Everyone in our local gardening groups who bought that tainted compost, their gardens are ruined.  I don't just mean for this season.  I mean they have to dig out the garden beds, and either find some isolated corner to dump the tainted soil or pay to have it hauled away.  Picture after picture after picture of stunted, blighty, yellow-brown, crumpled plants. Large swaths of bare ground with nothing growing but a few weeds. The owners desperate to find out what is happening.  I've probably seen that dozens of times this year.

There was a press release where the guilty party in conjunction with the ag board stated that the tainted soil could be composted for two years with some additives to neutralize the herbicide, then they could test for traces of it and the soil should be OK.

So if you have a few years to let this compost somewhere, maybe you'll be OK.

Grrr. If I was in charge this stuff would be outlawed, banned, hunted to the ends of the earth and burned with fire. We have a playing field next door that the council gets sprayed with aminopyralids each spring (any day now, I bet). Over a dozen mature trees around the edges have packed up over the last year and I keep losing young trees in my boundary plantings.

raw manure is what caused all the sickness from spinach and other stuff sever years ago. I would mix it with leaves and wood chips, if it is clean and not chemical infested, and get yourself a good big compost pile for next years use.

Charles,

A thought about potential contamination.

Maybe get a little pot and plop in a tomato or some fall season broadleaf veggie (spinach?) and give it a test.  Don’t eat anything from the test, just find out if the veggie grows normally or not.  This might be a cheap test you could perform while the rest of the pile is decomposing.

Just a thought,

Eric

I've been using horse manure for many decades and I've never had a problem. I find that horse owners care more for their animals than those who raise food for sale.
My problem is with the freshness. You're growing a root crop in fresh manure. If it's fresh. How many horses are at the barn where you got your horses. And how much manure did you get. If there are two horses and you got a pickup load the manure isn't fresh. And if it's not full of hay or woodchips then it's even older. The barn where I get my manure has no floor, so they don't use any bedding to soak up the urine. There's two horses there and they don't add very much to the pile in any one day.

If I had to use that manure for garlic, I think I'd spread it over the field and let it set in the sun for a month.

I don't import any manure or compost onto my farm. Any increased fertility is not worth the risk from herbicides and weed seeds.

Thanks, everyone.

Update:

The bioassay is not looking encouraging. Eight beans sprouted in the pots with plain dirt, only 2 sprouted in the dirt/manure mix, and one of those two seems to have kinda stalled. Also there are numerous little weeds in the plain dirt, and none in the manure mix.

I went out to the pile in the field, out of curiosity as to whether it would be killing the weeds near it. It hasn't (and in fact, 2 dandelions are growing up through it) but perhaps it hasn't reached the roots yet.

I may end up redoing the bioassay because the pots had sat outside in cold-ish weather for a few weeks before I brought them in -- though clearly that didn't harm the seeds in the plain dirt.

Starting to get a bad feeling I'm going to have to ask the horse stable owner to take the stuff back. Bunch of work to load it back in the truck and drive it back down there, but at least then it's off the farm.

In case someone else comes across this resurrected post, I wanted to answer specifically the tilling it in piece of the question. The whatever-cides being in the manure is certainly a concern, but has already been answered thoroughly.

Assuming we do not need to worry about any of the whatever-cides, and assuming we are ok with tilling (my personal opinion is that it is ok to do sparingly), then a lot of it would come down to timing. I would never put any kind of fresh manure on my garden (tilled or otherwise) and then plant in it without waiting. If you piled on the manure, tilled it in, in the fall in order to plant in the spring, then you would be fine. It would increase the organic matter in the soil and would be "composted" enough by the spring, not to be a problem. If you want to add some sort of nutrients at the same time as planting... then it needs to be well composted first.

Rob Lineberger wrote:Just to give you a frame of reference, there was a widespread distribution of mislabeled compost here in central NC this spring.  The compost had been made with an herbicide-tainted hay stock that had been labeled as organic.  This was one component of many in these tons and tons of compost, which were sold to garden supply centers, and they in turn mixed that compost into their own diluted mixtures.

Everyone in our local gardening groups who bought that tainted compost, their gardens are ruined.  I don't just mean for this season.  I mean they have to dig out the garden beds, and either find some isolated corner to dump the tainted soil or pay to have it hauled away.  Picture after picture after picture of stunted, blighty, yellow-brown, crumpled plants. Large swaths of bare ground with nothing growing but a few weeds. The owners desperate to find out what is happening.  I've probably seen that dozens of times this year.

There was a press release where the guilty party in conjunction with the ag board stated that the tainted soil could be composted for two years with some additives to neutralize the herbicide, then they could test for traces of it and the soil should be OK.

So if you have a few years to let this compost somewhere, maybe you'll be OK.

I had a small patch contaminated two years ago, and then grew oyster mushrooms in a thick mulch on the affected area, it grew most fall crops fine last summer. More anecdotal than science...

Hey, OP here. Looking back, I agree, uncomposted manure would not have been a great idea. Nowadays, anytime I hear of free horse manure, I ask what the horses eat. Usually there's at least one bought (and non-organic) component.

We ended up using some of the questionable manure to fill in the deep trench where we put the geothermal system for the greenhouse -- it was a great big trench and one truckload of manure disappeared into it.

We have chickens now, so in future I'll probably focus on hen manure in place of the horsey stuff unless they finally take the super-persistent chemicals off the market.

Joseph Lofthouse wrote:
I don't import any manure or compost onto my farm. Any increased fertility is not worth the risk from herbicides and weed seeds.

I absolutely agree with this.  Several years ago I ended any importation of any amount of hay, straw, alfalfa, lawn grass clippings, leaves, manures, compost, wood chips, soils, fill.  No store bought bags of potting soils or "top soil".  No commercial nursery plants (possible diseased plants, spores, possible invasives in the soils in the pots), no plants of any kind from anywhere with soil attached to roots.  I am now beginning to be concerned with contaminated seeds and have pretty much stopped doing seed trades as a result.  My land is quarantined for its protection, the soil is too critical for me to take any more chances.

I looked up amipyralid toxicity and was shocked quite frankly by what I read and saw...