? how to speed up decomposition of wood chips

bluesky_girl(Z6a)January 13, 2008


This is my first post in the Gardenweb forums.

I had to take down some huge trees in my front yard last fall, an American elm and red oak. It was a hard decision but I finally did it. Now I need to redo the front yard - I had a sycamore planted right away though not in the the same spot. My question has to do with the pile of wood chips left from the stump grinding. It's about 3 feet high and around 5 ft wide in the middle of the ivy bed that was under the trees. How do I speed up the decomposing process so I can use that material when re-doing the yard? (I'm planning on planting berry-bearing shrubs and lots of prairie-type plants until I can get my shade back in 20 years or so....)

Any suggestions ?

Thanks! Marge

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You can speed it up by spraying it with Miracle Gro, beer, and soda pop. That provides enzymes (from the beer), sugar (from the soda) and nitrogen. I think it's wise to simply turn the pile about once or twice a year, not more than that. If it's a bigger pile, you don't need to turn it at all.

    Bookmark   January 13, 2008 at 9:29AM
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kqcrna(z6 SW Oh)

I wouldn't use Miracle Grow. It is salty and not good for the soil organisms which you want to work at rotting all that wood. I would use something like blood meal instead, or grass clippings, coffee grounds, etc.

After having a stump ground a couple of years ago I scooped out some wood and added it to my compost bin, some I just went around flinging on top of lawn and flower beds. That reduced the size of the mound. For what remained under ground level I added grass clippings, mixed with a fork, and blood meal. I spread a thin layer of compost on top, about an inch or two, and threw down grass seed. It grew and looked fine by the next summer, which surprized me. I'm not sure if it will still look OK this summer... time will tell. That (deep!) blob of wood has to still be down there.


    Bookmark   January 13, 2008 at 9:55AM
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You need to add greens to the pile and turn it when it starts to cool down. Grass clippings, blood meal, plant matter from plants that were living when they were gathered, urine and a lot of other things are greens. I'm sure there's a list in an FAQ here some where.

    Bookmark   January 13, 2008 at 9:57AM
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dchall_san_antonio(8 San Antonio)

Speaking from a perspective of having repaired a considerable amount of wood rot in the house, there is nothing like continual moisture to decompose your wood chips. I would use a misting nozzle attached to your hose and leave it on from now until you are happy with the decomposition process.

    Bookmark   January 13, 2008 at 1:04PM
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water, sugar, & nitrogen are the 3 things I've had the best experience with:

When my neighbor cut down a big dead tree, she poured a whole bag (5 lbs? 10 lbs? something like that) of sugar on the stump & watered it in.

If you're having trouble gathering nitrogen right now, you can always buy alfalfa pellets at a feed store & soak them overnight & pour on the chips.

Alfalfa pellets stink, but they work!

    Bookmark   January 13, 2008 at 1:34PM
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Nitrogen is the key because it is the energy source for the decomposers. An organic source would be alfalfa meal; ammonium sulfate would also serve if your pH is high. Regards, Peter.

    Bookmark   January 13, 2008 at 5:17PM
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Kqcrna, the spot where the stump used to be, where the soil/chip mixture is now, is going to settle. Gradually, but inevitably, settle. Plan on adding topsoil, about an inch at a time, as this happens. You don't need to stir it, or mix it, or anything, but it's going to settle. (The wood is going to go away, isn't it?) So start a topsoil pile out back, and plan on adding topsoil, as needed.

    Bookmark   January 13, 2008 at 11:28PM
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I feel sad when stumps from such fine woods are ground up. Perhaps a local wood working or wood turning group might have been interested in the wood from the tree and stump. Now that I got that off my chest ...

Because of the high lignin content of wood, most of the decomposition will be done by fungii which will make the cellulose available to the bacteria. So if you want to decompose the chips, keep the pile moist and add a bit of slow release nitrogen material such as soya meal on an ongoing basis.

If you use chemical fertilizers I would add a very small amount more frequently because the nitrogen will become available immediatly.

How about a covering of soil to help keep the chips moist and capture some of the nitrogen? A clayey soil will have a higher CEC.

Here is a link that might be useful: The Effect of Lignin on Biodegradability

    Bookmark   January 13, 2008 at 11:47PM
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kqcrna(z6 SW Oh)

philes: Yes, I have been expecting that stump area to sink, but it hasn't yet in 2 years. I never have extra soil to start a pile. Rather, I always need extra. Despite adding compost and OM regularly, I never have extra soil. (My property is flat, too, so soil isn't eroding and washing away downhill).

If/when that area does sink, it will add compost and/or soil. I have no idea how long it might take that giant pit of wood to rot down there!.


    Bookmark   January 14, 2008 at 7:28AM
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What the bacteria that will digest that cellulose need to digest that cellulose is a source of protein, Nitrogen. Synthetic fertilizers are known to be harmful to the soil bacteria and should not be used. Sugar can be a stimulant for the bacteria, just as it is for children but that is still empty calories and like it will eventually do to children it will kill your soil bacteria. Alcohol does the same thing as sugar, because alcohol reverts to the sugar it came from fairly quickly and it is that sugar that stimulates the soil bacteria.
Just add to the pile of wood chips a good, organic Nitrogen source and know it will take some time for the bacteria to work on that pile.

    Bookmark   January 14, 2008 at 7:44AM
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Thanks for all of the suggestions. I think here's what I'll do. Since I was going to pull the ivy anyways to start with a clean bed, I'll simply have the ivy chopped up and added to the wood pile, along with some of the soil there. And keep it moist. Probably add some alfalfa meal too. Lenny, the tree guy who left me this wonderful pile, said it would settle down quickly but Karen you confirmed my suspicions that it will be a while for that to happen. There's many holes in the lawn and in the ivy bed anyways from the wood hitting the soft wet ground. The whole area needs to be reworked.

I'll see how far along the wood pile has broken down by summer and perhaps use the remaining for paths in between my raised beds in the backyard. I can't leave it in front until it's entirely gone - it's too much of a sad reminder to me.

Cowgirl2, your remark about saving the wood ? Yes - I wish that could have happened too. On another note, my neighbor's tree in the backyard lost a huge branch last fall and I did ask for that wood. It's Osage orange, a wonderful wood, that I'm going to either ship to my brother-in-law for his wood-turning hobby or donate to the local woodworking group. They will know what to do with it.


    Bookmark   January 14, 2008 at 8:37AM
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It is a HUGE undertaking to remove a stump from a tree that was as established as the posters. It would probably require an incredible amount of earth to be removed, chainsaws a plenty to attack the larger roots, and then a large truck with chains to get it out. I would not want to be a part of that, but if you could get it out somewhat easily (ie it wasn't near a house and you could just saturate the ground for a couple days and then excavate with a front-end loader or other equipment it would be a nice piece to work on.

    Bookmark   January 14, 2008 at 11:22AM
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spiced_ham(z5 OH)

Initially the amount of bacteria and fungi, which break down the wood is very small in the pile. In order for the populations of those oranisms to grow they need nitrogen in order to make proteins/enzymes, to make new "bodies". The mass of a living organism is mostly carbon, but the machinery that carries out the chemical reactions of growth and metabolism are nitrogen containing proteins/enzymes. The nitrogen is not an energy source, it is a building block source. The wood-carbohydrate is the energy source for population growth.

"Greens" are somewhat high in nitrogen from their formerly living cellular contents. Alfalfa (hay or pellets) is higher than most. Manures are high in nitrogen from animal urine. Commercial fertilizers are the most concentrated source of nitrogen. Nitrogen content is the first of the three numbers on the package. You do not want to add a 18-18-18 vegetable fertilizer or a 5-50-9 flower booster fertilizer if all you want is the nitrogen. Lawn growth fertilizers with a very high first number are usually mainly urea-nitrogen, but may have ammonium and or nitrate salt sources (also good). Sometimes you can get ammonium nitrate or ammonium sulfate as a nitrogen source. A "Salt" is a chemical class, and has nothing to do with saltiness (sodium build up) harming plants or the soil. Plant roots are designed to take in ammonium and nitrate salts, which are more prevalent in nature than urea, but they do fine taking in urea too. Fungi and bacteria use it all too. Organic fertilizers are usualy low concentration fertiizers (5-5-5 organic vs 20-20-20 chemical) so are more expensive for the amount of nitrogen, phosphorus and potassium they provide.

The easiest way to get a pile of wood chips composting is to add 1-2 pounds of high nitrogen fertilizer (high urea lawn growth fertilizer) per cubic yard (3ftx3ftx3ft)of damp wood chips. An equal part of sugar (easy energy) in the mix can jump start the population growth of the decomposition organisms, and a little dirt/unsterilized compost mixed in will act as a starter source for those organisms.

Beer has negligable amounts or protein/enzymes, and what little is there are not the type that break down cellulose and lignin(wood). The alcohol and carbohydrates act the same as sugar to the decaying organisms (energy food).

Hope this helps.

    Bookmark   March 12, 2008 at 11:19AM
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