asphalt tar roof shingles a good mulch???

Tried finding out some data on asphalt roof shingles as to whether they are good for plants or bad. The Internet is mixed on this question. A
University says that tar is toxic to plants. But that does not make sense relative to the known fact that each year now I receive baby trees grown in tar-paper pots.
What brings me to this issue is the fact that I have about 50 bundles of unused asphalt shingles. I have several options-- 1) sell them cheap to get rid of 2) haul them to the dump 3) use them as a mulch or ground cover in the tree windbreak and perhaps elsewhere in the gardens.
So, what is the straight truth about asphalt shingles relative to plants? Are they toxic. Or do they help plants in providing acidity and micronutrients to the soil as well as acting as a mulch.
If I recall, raspberries seemed to love the soil where trash and tires and shingles were dumped.
So who is correct, the college professor who says tar and asphalt is toxic to plants or the commonsense inference that since tar-paper pots are normally used with plants says it is beneficial to plants.
I suspect the tar in asphalt shingles provides much needed sulfur to the soil and makes a base-pH more acid pH.
The science literature on tar in soil is contradictory.
Archimedes Plutonium www.archimedesplutonium.com www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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I have plenty of grass growing thru cracks in the asphalt road and path outside my place, and many weeds besides. Also there is lichen growning on my slate roof.
We used power kerosine (a high-aromatic solvent) to kill weeds in the old days, but asphalt has lost all its aromatic solvents due to evaporation.
Don't forget that asphalt and tar are two different things, the former from pertoleum and thelatter from coal.
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Mon, 30 Aug 2004 11:08:33 +1000 Peter Jason wrote:

What exactly is the chemical difference between asphalt and tar?
Apparently there is alot of common language confusion between tar and asphalt. Most everyone who sees a black sticky substance calls it tar and thinks that tar is what makes up asphalt.
There is even tar in cigarrettes but there is no coal in cigarettes.
So, should the tar paper pots that my trees come in be more accurately called asphalt pots?
Posted to sci.chem and sci.materials for someone who can clear up these definitions.
Archimedes Plutonium www.archimedesplutonium.com www.iw.net/~a_plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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You are correct. "Tar" is a pretty loosely used word here. Basically it means 'sticky gunk in the condenser`. Asphalt, coal tar, vegetable distillates, (eg. 'Pine Tar` or the 'tar` in cigarettes, your fireplace flue, or your plant pots), are different substances with different components and therefore, different toxic properties. Your shingles, if they have lost their odor, are probably relatively benign, but I doubt they'll do your garden any good. Here in the northeast we get far more sulfur than we need from acid rain. Best of luck,
Pragmatist "Just about the time I mastered getting the toothpaste back into the tube, they came up with this STRIPED stuff!"
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someone wrote:

I guess the best test is not asking but experimenting. Already I see the weeds and grass growing the best near the shingles laying on the ground. What I am going to do is place a few around some plants to see if they do better than those without.
I suspect the sulfur content is beneficial because our soil is alkaline.
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Yeah sure, Archie.
Like your sniffing glue must be good because it helps hold your brain cells together.
Using tar shingles as mulch is a bad idea for the same reasons mulch from ground up tires is bad. Just have your trash hauled away and get it over with.
Do your own Google search research, you blithering idiot.

weeds and grass growing

place a few around

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