Did I mess up my soil with sawdust?

So last year I tried to make a hot compost pile using lots of different materials. Veggie scraps from a cafe, lots of coffee grounds, leaves, grass, green yard waste, stuff like that. I think the centre heated up only for a short time, it probably never got quite big enough. One input was buckets of horse manure from the local rodeo grounds mixed with sawdust. Maybe 6 buckets worth, maybe more, I can't remember.

The pile looked really good this spring, it was full of red worms.

I used the compost this year but could still see some sawdust in the most composted part of the heap. Now nothing is really growing in my garden. Plants that have bothered to sprout are stunted and seem to stop doing anything after a while. The only thing that seems to have any vigor are the broad beans and maybe the bush beans too (hard to say because I also have terrible slugs for the first time ever!) The potatoes might be ok too, time will tell.

Did I screw up my soil with the sawdust? It's not like I used a truckload or anything! What can I do now?

I've been a long time lurker on this forum....hello to you!

The problem may not be so much the sawdust, but what was ingested by the horses before it came out the other end. Horses are fed vast amounts of wormers, drugs of various sorts and have a high probability of being fed hay that has been sprayed with herbicide. It is a very common occurrence for people to spread bought manure and have their gardens become toxic to plants. Many have had to remove the top soil and replace or grow in another location for a few years or more depending on what was used on the hay fields. Not saying this is the problem, but it sure sounds like a strong possibility.

I bought grass hay one year to top up my own. Because I knew of this problem, I made a new manure pile in a problem weed area when I cleaned the corrals in the spring. Sure enough, there were no weeds growing on the top of the heap that summer; bad sign. I never buy hay any more. Its safer to down size to a self- sustainable level for the bad times.

Ugh, yeah that possibility has crossed my mind as well. I just learned of Aminopyralid a few days ago. I don't see the curling leaf evidence of that particular herbicide, but there are hardly any weeds growing! This would not be a good turn of events.

The lesson here (that i seem to need to learn over and over) is to listen to that gut feeling! I knew using poo from unknown sources might pose a risk of perhaps medications or invasive weeds from other places. But last year I didn't know that herbicides could be passed through and animal and compost heap to the garden.

It really didn't seem like "too much" sawdust in my heap.

I have horses without wormer or herbicide and I find that fresh manure (with sawdust) leads to a lot of grass growing in a very short time. Like within 4 days with watering I see grass coming up.

It sounds like you have brought in residual pesticides/ herbicides contained in the manure.

You can remediate this problem with mycelium, lots of mycelium.
If you have access to native mushrooms, gather as many as you can and put them in the blender with some water, pour that resulting slurry over your affected areas.
It will take some time but the mycelium will do their job and you should get better results every year after you inoculate.
It will take one full year to begin seeing good results.

Also, add some mulch to keep the fungi happy. And keep things damp.

The historic museum I volunteer at brought in an herbicide contaminated load of compost; it was three years before they got anything to grow again.

Thank you for the suggestions. I am surrounded by forests so I'll see what I can do about mushrooms. Though it is somewhat dry in this area. Good excuse for a hike!

Is contamination like this something I can have tested?

Now, if it does turn out to just be a case of nitrogen being robbed by woody stuff, could coffee grounds and diluted pee help to fix it?

Flinthoph Luthhaughmer wrote:
Now, if it does turn out to just be a case of nitrogen being robbed by woody stuff, could coffee grounds and diluted pee help to fix it?

Yes. And adding those things won't hurt,no matter which it is, so give it a try.

IF your soil/garden problems are a result of the sawdust you put into your compost, it will not be a long-term screw-up (and I'm not convinced that this is, in fact, the source of your problem, although it may contribute to it).

Just continue to build soil with organic mulches (comfrey, other bio-mass, compost, wood chips) and keep a living root in the soil for as long as you possibly can throughout your growing season. Perhaps you'll need to cover-crop your land for a season. Get a nitrogen fixing cover crop mix and be sure to buy a microbial innoculent so that the seeds have the right bacteria in order to fix nitrogen. I order mine from GrowOrganic.com.

http://www.groworganic.com/cover-crops/annual-cover-crops.html

If there were some toxic chemicals/medications/de-wormers in those buckets of sawdust, the fungi and micro-organisms will break them down or render them inert.

It takes time to build soil. Don't be discouraged. Keep the soil covered with organic mulch, and keep plants growing in that soil so that they can continue to pump the life-giving sugars and proteans into the soil via their root exudates. Next year it will be better, and the year after that, better still.

Flinthoph Luthhaughmer wrote:Thank you for the suggestions. I am surrounded by forests so I'll see what I can do about mushrooms. Though it is somewhat dry in this area. Good excuse for a hike!

Is contamination like this something I can have tested?

Now, if it does turn out to just be a case of nitrogen being robbed by woody stuff, could coffee grounds and diluted pee help to fix it?

Yes, you can test for contamination or you can take samples (use a grid and label each section so your results will be traceable to each grid plot) if you want to test yourself, there are kits available for not a lot of money.

If it is just nitrogen defect, yes your ideas will work quite well.

Joe lampl, who hosts the show "growing a greener world " had this happen in his personal raised bed. He said light and air will cure it. So turn it a few times. It's very likely it will be fine for next growing season.

Horse manure is my main source of fertilizer. I've never had the problem and I do buy round bales for them.

I've worked in the horse industry for 20 years and I think there are far fewer chemicals being given to horses than people might realize. Modern deworming protocol usually involves taking a fecal sample and giving them a dewormer 2X per year, for a single day. If a horse has been infested or is a "high shedder", they may be dewormed more frequently, but that is a fairly small percentage of the population. So, in a lot of barns, horses will have dewormer in their systems a mere two days out of 365.

If they get a serious infection, they will be given antibiotics, but this happens very rarely. You might see more frequent use of NSAIDs in a stable where they are in competitive training or with an older horse with arthritis, but these are very small amounts.

If the hay had so many herbicides on it that it would kill a garden, it is unlikely that the horses would fare particularly well, either. I'm not saying it can't happen, but I doubt this is the main culprit.

My point being, I think it is unlikely that six buckets of horse manure is your culprit unless you are getting manure from a place where the horses are very ill. I would be more concerned about the bedding itself than the manure.

Putnam, my take on the whole horse manure is whether a "persistant" herbacide was used to grow the hay. Meaning it doesn't go away. From a consumer standpoint you can buy round up that dissipates in 30 days. There's also round up 365, Meaning it keeps killing for a year. Common sense tells me the long term killers are gonna stick around.

I do agree with you on medicine. It's of no concern to me, but each person has their own line in the sand.

I agree. I certainly think people should be aware of what is in manure and make educated choices about whether or not it is appropriate for them. And it's impossible to know the culprit from behind a screen. If I had to play the odds, though, given what I know about haying and horses, I'd be putting my money on a nitrogen tie-up from the sawdust. Especially given that the nitrogen-fixers seem to be alive while everything else has suffered. If it is an herbicide issue, that'll be a problem. If it is a nitrogen issue, that should eventually resolve itself.

I don't actually use the manure and bedding readily available to me due to the long breakdown period necessary and the increased nutritional imbalance. I'll borrow from Steve Solomon:

Very little grain is produced in our region, so there is little or no straw available for bedding animals. Instead, farmers and horse owners use sawdust. The sawdust is highly absorbent, so the animals are usually allowed to walk on the same bedding for quite awhile before it gets too odoriferous for the comfort of humans. The droppings become broken up and thoroughly mixed into the sawdust; it is nearly impossible to rake out solid chunks of manure from the mix. The best you can say about this sort of “manure” is that most of the urine has been absorbed too.When wetted down and heaped up, this type of manure will heat up a little, but it never gets very hot. If you believe you must use this stuff, make sure you keep the material moist, turn the heap every few months, keep it covered during the winter, and let it cure for at least two years.

Solomon, Steve (2009-06-01). Growing Vegetables West of the Cascades, 6th Edition: The Complete Guide to Organic Gardening (GrassRoutes) (p. 90). Sasquatch Books. Kindle Edition. "

Plants always concentrate potassium in their fiber and other woody parts. So local grass hay, sawdusty horse manure, and our vegetation in general is unbalanced in favor of potassium. Our grass hay and sawdusty horse manure contain a lot less calcium, magnesium, phosphorus, and proteins (nitrogen) than they otherwise might. Build a compost heap of that stuff and rot it down, and you concentrate all of the minerals in the vegetation and manure. Essentially, you end up further concentrating potassium.

Solomon, Steve (2009-06-01). Growing Vegetables West of the Cascades, 6th Edition: The Complete Guide to Organic Gardening (GrassRoutes) (p. 30). Sasquatch Books. Kindle Edition.

My friend brings her daughter to riding horses every week, and says, that they are sprayed lots of poison to protect from flies after each ride...I certainly do not feel like using horse manure unless I know, how horse is taken care of.
I have guinea pigs, and I use wood pellets with their urine on top of my beds as mulch together with other things like straw and wood chips. My plants grow well. I think urine being high in nitrogen helps to prevent saw dust nitrogen problems.

It depends....did you use new fresh sawdust fresh from the saw or the old black sawdust that has been out in the elements 6 or 7 years until it has turned to the texture of black crumbly dirt?  I have some seriously compacted rocky soil at my property and it has had to be amended and reworked before it would grow anything....i came up with a mix of one third black sawdust one third black soil that used to be rabbit manure about 10 years ago and the last third is half peat moss and half sand....been doing this awhile and so far haven't had much of a problem except that it's HARD WORK to dig down through all that clay and rock to create a base for any kind of raised bed....

Hi Sherry,

Welcome to Permies!