[maddy]

I hauled several loads of beautiful, partially-decomposed sawdust from a local mill to use on my garden paths. I spread it heavily but kept it well away from my raised rows where the plants are growing. After covering two of the paths, I came back the next morning and found that my inch-high carrots which bordered one of the sawdust-covered paths had turned grey and were dying. Okay, I thought, it's been really rainy, so I chalked it up to that. The next day, I found my celery--which had looked great the day before--turning white. And on the other side of the sawdust-covered path, my squash looked limp. Still refusing to believe that my dying garden had anything to do with the sawdust, I covered a few more rows. I went out today and found my brassicas limp and the peas dying. And to top it off, I spotted a patch of clover on which some sawdust had fallen, and it had turned grey and shriveled up!

I'm now convinced that it's the sawdust. It had a very ammonia-like smell when I first applied it, and when I put a chunk of wood from the pile up to my nose, the ammonia smell was quite unmistakeable. What's going on? The mill swears that this is untreated wood, with no cedar. Any ideas?

 

[oldasrocks]

I have had the same problem to an extent. I use wood chips for bedding in the chicken house. It gets scooped out and applied in the garden. The areas I put it in won't let anything germinate. So far the bedding plants are growing OK in those areas. Weeds are not even germinating in there which is the only good thing. I have a 6 ft circle that I normally grow Marigolds in and not one germinated?????? So put in 8 leftover tomato plants and they are doing well.

My sister in Georgia put sawdust down around her tomatoes and they all died .

I have no answers but at least you can see several people are having the same problem.

 

[ET1 SS]

If it were cedar you would smell it.

Since it smells like ammonia that means it is saturated in urea. That may take a few rains to leach out completely. But urea should not present any threat to veggies.

Lumber that has been 'treated' means it would have been saturated with copper. Again not a threat to veggies.

It sounds to me like a fungal infestation.

Examine leaves closely. Look for a white powder or a rusty brown powder.

 

[maddy]

Where would the urea come from?

I originally was also thinking I had something fungal, but wherever I put the sawdust, the adjacent plants keel over 12 or so hours later. I don't think a fungus, even if carried in the sawdust, would behave like that.

 

[RJ2019]

Sawdust leaches the nitrogen from the ground it's on in order to decompose. Your symptoms seem a little different, but it is one of the problems with using it.

 

[Paumon]

Sawdust leaches the nitrogen from the ground it's on in order to decompose. Your symptoms seem a little different, but it is one of the problems with using it.

I agree with that. Sawdust sucks up nitrogen out of the soil and deprives plants of nitrogen, and it can also dehydrate plants very near it. Around here it gets put down on walking paths and trails in parks and other areas to kill and discourage unwanted plants that may cause tripping hazard. It doesn't discriminate about where or what it takes the nitrogen from and any wanted, cultivated plants that border the paths should be a minimum of 3 feet away from it on either side of the path. It doesn't have to be a very thick layer of sawdust on the ground for it to have an effect on nearby plants. Wood chips will do the same thing but to a lesser degree than sawdust. Bark chips are gentler, they cause the least damage.

When sawdust hasn't been fully composted it gets a strong ammonia smell from being saturated with too high a nitrogen content that it takes out of the soil.

My suggestion would be to not put sawdust down between your rows of cultivated plants, and if you must do so then use it sparingly and be prepared to compensate your cultivated plants for nitrogen deprivation.

.

 

[NRA_guy]

Sawdust leaches the nitrogen from the ground it's on in order to decompose. Your symptoms seem a little different, but it is one of the problems with using it.

I built one of those large 3-bin compost structures years ago. In the fall I would put dead leaves from my lawn mower's grass catcher in bin no. 1. Then after a month or two I would stir the leaves.

After about a year I would move the bin's content to bin no. 2 and stir occasionally.

About a year later I would move the contents to bin no. 3 where it would sit until I needed it. It was very well composted. I would put it in my raised beds (32 ft. x 4 ft. beds).

After a while I noticed that my vegetables were doing poorly and I checked the soil. The nitrogen was 0%.

I think that composting (rotting organic matter) takes the nitrogen out of the decaying organic matter.

 

[doc-]

The sawdust smells like ammonia before it's put down, therefore it's not the soaking up of soil N that's producig the NH3. Besides, the plants detreriorate within a couple hours-- way too fast for a leaching process to be at work.

Forgotten by most-- plants need oxgen to live too. The strong ammonia smell and fast action suggests the ammonia is "asphyxiating" the plants. Heavier than a ir, it settles to the ground while forcing the O2 higher, away from the plants.

What is the source of the ammonia? Ammonia is ultimately derivedf rom protein, and wood has almost no protein in it, so it's something ther sawdust has soaked up fro somewhere-- urine, decomposing bugs or rodents, etc.

 

[Evons hubby]

Interesting… I’ve used sawdust as mulch for many years without any problems.

 

[Alice In TX/MO]

The Disadvantages of Sawdust for Garden Paths

The Disadvantages of Sawdust for Garden Paths. Sawdust is an inexpensive option for mulching your garden paths, but it may not be the best value for your money. The light color may brighten the look of shady gardens at the expense of the plants; sawdust's composition can leach nitrogen from the...

homeguides.sfgate.com

 

[maddy]

I've used sawdust before also, and have never experienced any smell other than a clean "lumberyard" smell. I'm wondering whether the lumber company might have added urea to the sawdust to speed decomposition? I'm going to go back there today and ask.

 

[GTX63]

Sawdust will draw nitrogen from the soil, but as the matter decomposes, it goes right back down where it came from.

 

[geo in mi]

Maybe you got the bottom dregs, which were so deeply covered that you got the products of aneorobic composting instead of oxygen/aerobic compost. Aneorobic decomposition takes place in the absence of oxygen and it has a pH of about 3 or 4--highly acid. Wouldn't take much, if there is any moisture at all, to leach out overnight and destroy root hairs.

OR, you got a big slug of walnut sawust from the day the mill ran a semi-load of walnut logs--again highly acid and pooled with juglone......

No mill owner out there will turn the sawdust three or four times, mix it with soil organisms and greens to get the proper C : N ratio and let it heat up each time for you.

Nothing wrong with using bulk sawdust. Just caveat emptor.

geo

 

[RJ2019]

I built one of those large 3-bin compost structures years ago. In the fall I would put dead leaves from my lawn mower's grass catcher in bin no. 1. Then after a month or two I would stir the leaves.

After about a year I would move the bin's content to bin no. 2 and stir occasionally.

About a year later I would move the contents to bin no. 3 where it would sit until I needed it. It was very well composted. I would put it in my raised beds (32 ft. x 4 ft. beds).

After a while I noticed that my vegetables were doing poorly and I checked the soil. The nitrogen was 0%.

I think that composting (rotting organic matter) takes the nitrogen out of the decaying organic matter.

Yes, decomposition needs nitrogen. But when it's finished decomposing it releases the nitrogen back to the soil. One of the issues with wood chips and sawdust is that they REALLY suck the nitrogen out of the soil.

 

[GTX63]

Wood chips go into our compost bin. What goes in this year will not be used until next year. My neighbor brings over a small trailer load of white oak and pine chips from time to time. What I added to our compost bins in the Spring on 2021 today looks like rich black earth. I used a bit of it for planting 8 short rows of Turnips last week. I dropped the seeds into their holes mid afternoon and by dusk the next day I had sprouts coming out of the ground.

 

[doc-]

Sawdust will draw nitrogen from the soil, but as the matter decomposes, it goes right back down where it came from.

The reason you need to fertilize with N so heavily and repeatedly is because soil bacteria take atm N2 and turns it into NH3, but the NH3 is very volatile-- it outgasses to the air quickly where it's oxidized again into N2 & O2...Even if you didin;t carry N away with your harvest, the field still needs an on-going way to fix atm N....That's why fresh manure will burn plants with hi N, but aged manure has much less.

 

[cjennmom]

Is it only the form (saw Dust) that’s a problem? I’ve been thinking about expanding my garden beds and using the wood chips mulch for my bushes and flower beds.

Sawdust leaches the nitrogen from the ground it's on in order to decompose. Your symptoms seem a little different, but it is one of the problems with using it.

 

[GTX63]

Compost your wood chips. Making your own should be preferable to store bought since you will know when they were chipped and what has been put on them.

 

[arachyd]

My first thought is that it contained a large percentage of walnut sawdust, as geo in mi said.

 

[RJ2019]

Is it only the form (saw Dust) that’s a problem? I’ve been thinking about expanding my garden beds and using the wood chips mulch for my bushes and flower beds.

Wood chips also leach the nitrogen from the soil. Chips break down more slowly and aren't quite as problematic as sawdust but I still don't recommend it.
I know someone who uses wood chips on their garden plots, did some soil testing for them and they were extremely low in nitrogen.