I had a large, red oak tree cut down and kept the chips so I could use them for mulch.
After reading some things, I'm wondering if it was such a good idea. Does oak make for good mulch or does it change the soil pH too much?
Lee Reich, in his "Simply Soil" column a few issues of Fine Gardening back addressed this issue and stated that that whole idea of a mulch from various trees would change your soils pH is a myth, and it is. Use the Oak and do not concern your self that it might change your soils pH. A couple of years ago, now, Dr. Abigail Maynhard from the UCONN Agricultural Research Station at New Haven, Conn also wrote an article in Organic Gardening magazine that showed this whole idea that various types of organic matter, notably Oak leaves and Pine needles, would change soil pH to be a myth.
You will also find people that will continue to spread the myth that putting a hardwood mulch on top of your soil will "rob" your soil of Nitrogen. That too does not happen and that myth too Lee Reich tried to dispel in his column.
West central Michigan along the lake shore
A sign of a good gardener is not a green thumb, rather it is brown knees.
Edited 10/9/2006 5:26 pm ET by KimmSr
As long as the tree was healthy, Id say.
I use wood chips all the time. I have a friendly tree company drop off a truckload once a year. When the pile is fresh it steams and is very hot in the center, probably due to some leaves ground up with the branches as a nitrogen source. I never even know what kind of trees the chips are from, except they leave out any poison ivy when they are going to bring me a load.
When I spread the chips in the garden the earthworms eat them, and break them down. The worm castings *add* nitrogen to the soil. Here in Connecticut we have huge earthworms called "nightcrawlers". They eat a lot.
When we bought this house I created a perennial bed near the street on a narrow strip of land that was all fill, mostly broken-up asphalt and rocks, with a thin layer of soil on top, street in front, sheer drop-off 20' back. At first it was mostly ornamental grasses, since they will grow in almost any type of soil.
It's our only sunny spot. The rest of our yard is on a north facing slope and is mostly wooded. The chips and earthworms have, over the years, created topsoil so now I have a lot of flowers, and finally, this year, I'm planting peonies and oriental poppies.
Wood chips can be a good thing in the right circumstances!
Absolutely. I have numerous times put freshly chipped wood down as mulch and have seen the plants green up and grow more than some nearby that did not get those wood chips, with no sign of chlorosis. I have also put down old, aged wood chips and seen the same thing. I have not seen a mulch "Rob" the soil of nitrogen in over 36 years of gardening, unless what was supposed to be a mulch becomes a soil amendment, it is mixed into the soil instead of put on top of the soil. A material that was supposed to be a mulch that is mixed into the soil is a soil amendment not a mulch.
I've read some of your other posts here while I admit I was lurking and you seem to know a lot about soil and making compost and the benefit of worms and such. Can you tell me if it's true that earthworms will eat the wood chips as kousa said? Yeah, I have strong opinions about some things but I still need to learn as much as I can from other gardeners.
Edited 10/27/2006 9:18 pm ET by JEF1
The whole Soil Food Web, all the wee buggers that live in our soil, work at digesting those chips, as well as anything else we plunk down. Starting with the Pill Bugs/Sow bugs, Centipedes, Millipedes, Ants, right on down to the microscopic bacteria, nit just the earthworms. I would suspect that wood chips would, initially, be too large for earthworms to get their mouths around and they would need one of the others do cut the wood chips down to size.
re: worms and wood chips... I have a friendly arborist who dumps a truckload of wood chips at the end of my driveway about once a year. I like to get them in the fall and then they just sit all winter. Can be any variety of wood, always a mix. By spring I have always found them PACKED with earthworms. I have so many in there that I volunteered to supply two brownie troops with worms for their earthworm project. My daughter and her friend picked out forty-plus 5" worms in about 20 minutes with no effort (and a lot of giggles). I don't do anything to these wood chips. They are sitting on asphalt, in a pile about 4' high. The area dips so it would be a puddle if the chips weren't there. They usually stay pretty wet. In the spring and all summer long I use them to mulch everything--the veg garden, under the rhododendrons and evergreens, in among the flowers. Anywhere I don't want weeds. The only thing that doesn't get mulched are the bearded iris. I would fertilize my gardens etc. if I only got around to it, but I rarely do. I have never added anything besides basic 10-10-10 and haven't had any nitrogen problems--except in my fishtank, but that is another story :)
zone 6 gardening in the woods with 30,000 deer
zone 6 gardening in the woods with 30,000 deer
Thank you for stating the situation with wood chips and sawdust so clearly. The argument of nitrogen use in wood chip decomposition as gone on too long. The critical point of mulch vs soil amendment is seldom stated so the argument continues with little education happening. My experience came when I bought a load of "well aged" sawdust from a nursrey. I t looked and smelled like it had composted but when I top dressed a flower garden the plants stopped growing and turned yellow. Not until I watered in a soluble nitrogen did they recover. It has been many years ago but I had probably worked the sawdust into the soil as an amendement. Since then, whenever I get sawdust from a sawmill I always dig from around the edges of the pile in places where the sawdust has mixed with the soil and the weeds have begun to grow. This material has been an outstanding soil amendment.
I've found the same. But I still don't like to use wood chips. It is not a myth that raw wood uses sitrogen to break down, robbing your plants of some of that nutrient. It makes great pathway material though.
"The plants have been good to us." Lester Hawkins
The wood chips will use nitrogen as they decompose, but they will not "rob" it from the soil and create a deficiency of the nutrient. The decomposition happens only where the soil and mulch meet, so plant roots will not be affected adversely.
--Steve Aitken, Editor, Fine Gardening
Now there's a detail I never knew! Thank you. In such a situation does one need to make sure to work applied fertilizer into the soil to get it below the mulch layer?
Let me preface my answer by saying that everything I think I know about soil, I learned from Lee Reich.
He would say that the fertilizer doesn't need to be worked into the soil, merely laid on top. You would then put the mulch over it.
And in reality you would not even need to add any fertilizer under the mulch, even wood chips.
Steve, You said that wood chips would "use" nitrogen, but not "rob" it from the soil. Isn't that just a matter of semantics? If they're using the nitrogen, they'retaking it from someplace. That someplace is the soil, right? If they're taking it from the same environment in which the plants are growing, then they're robbing it from them. Regardless of whether the roots are 6" away from the surface of the soil. It's no different from the overall general environment in which humans live. What's dumped upstream from me, eventually filters down to my well. It's invading my environment. I look at the wood mulch as doing the same to the plants. Only in this case it's taking (robbing) as opposed to contributing.
Also, no offense to Lee Reich, whom I respect, but there are an equal number of highly credible sources out there (Googling is easy) that differ. Or state that bark, chips or sawdust mulch should at least be left to decompose on its own or incorporated in a compost pile and after a year or so, then use it as a mulch when its nitrogen requirements aren't so high as to interfere with plant growth - especially the establishment of new plantings or seed beds.
If the nitrogen-robbing naysayers at least agree that bringing fresh wood mulch into contact w/roots can exacerbate nitrogen robbing, then certainly, I'd think, it wouldn't be a good idea to use that mulch on shallow rooted plants or in annual, vegetable or any other beds that are routinely either tilled, minimally cultivated or just disturbed by virture of constant replanting.
Both sides can state what they perceive and believe as "facts". I suppose there will always be disagreement on this, and in the end I think it just comes down to agreeing to disagree. (Corny, but I think that approach still works.) JEF
Edited 10/26/2006 10:39 am ET by JEF1
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