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Posted: 12/29/2005 2:49:09 PM EDT
I drive past a tree service yard in the morning ont he way to work...I always see these huge mounds of what looks like mulch with what I guess is smoke wafting up from them.

Someone once told me that the material smolders but I kind of dismissed that since it didnt make any sense to me.

Anyone want to educate me about mulch?
Link Posted: 12/29/2005 2:51:27 PM EDT
I would guess the mulch retains heat from the sun and gives off steam when the outside temp drops.
Link Posted: 12/29/2005 2:53:07 PM EDT
[Last Edit: 12/29/2005 2:55:08 PM EDT by Tango7]
What was the ambient temp that time of day?

The 'smoke' you were seeing was probably steam coming from the decomposition (rotting) of the organic matter. Heat is a byproduct of that decomposition, and it is used to break down the waste into usable form.

I have seen actual fires in mulch piles - kind of like the "spontaneous combustion" that you get from linseed oil soaked rags in a poorly ventilated pile.

From Mastercomposter.com


A large pile of immature compost or mulch can most certainly experience spontaneous combustion. Anaerobic and high-nitrogen pockets in the interior can generate methane and alcohols and other flammable gases, which slowly migrate outward through the pile into areas that are above 140 degrees F due to aerobic composting. It is quite possible that you will get the right mixture and concentration of gases hot enough to flash, and then you have a smoldering spontaneous combustion. If wind conditions are right, enough oxygen may be infused into the pile to generate open flames across the dry material near the surface.


From North Carolina Dept. of Environment and NAtural Resources


When ground organic debris is put into piles, microorganisms can very quickly begin to decompose the organic materials. The microorganisms generate heat and volatile gases as a result of the decomposition process. Temperatures in these piles can easily rise to more than 160 degrees Fahrenheit . Spontaneous combustion can occur in these situations.

Spontaneous combustion is more likely to occur in larger piles of debris because of a greater possibility of volatile gases building up in the piles and being ignited by the high temperatures. If wind rows can be maintained 5 feet to 6 feet high and 8 feet to 10 feet wide, volatile gases have a better chance of escaping the piles; and the possibility of spontaneous combustion will be reduced.

Turning piles when temperatures reach 160 degrees can also reduce the potential for spontaneous combustion. Pile turning provides an opportunity for gases to escape and for the contents of the pile to cool. Adding moisture during turning will increase cooling. Controlling the amount of nitrogen-bearing (green) wastes in piles will also help to reduce the risk of fire. The less nitrogen in the piles the slower the decomposition process and consequently the less heat generated and gases released.

Large piles should be kept away from wooded areas and structures and shall be accessible to fire fighting equipment, if a fire were to occur. Efforts should be made to avoid driving or operating heavy equipment on large piles because the compaction will increase the amount of heat build-up, which could increase the possibility of spontaneous combustion.

Link Posted: 12/29/2005 2:53:27 PM EDT
[Last Edit: 12/29/2005 2:53:54 PM EDT by The_Reaper]
Decomposing compost generates quite a bit of heat.
Usually never enough to spontaneously ignite because it is too wet,
but enough that steam can be seen coming from it.

Arrgggg. Beaten by 20 seconds
Link Posted: 12/29/2005 2:57:01 PM EDT
I remember working at a nursery when I was younger......we used to bag our own mulch from a huge mulch pile we had on the property. In the summer nobody wanted to get anywhere near it because of the heat, in the winter it was the best gig because it was so warm standing right in the middle of it......
Link Posted: 12/29/2005 2:57:14 PM EDT
When you see a smoking mulch pile, run away! It's the Global Warming! You didn't listen, did you?
Link Posted: 12/29/2005 2:58:09 PM EDT
heat
Link Posted: 12/29/2005 3:02:55 PM EDT
Piles of horse manure can spontaneously catch fire from the heat caused by decomposition.

(no really. this is not a horse shi'ite story)
Link Posted: 12/29/2005 3:03:31 PM EDT
That smoke ain't comin' from the mulch, man.
Link Posted: 12/29/2005 3:04:52 PM EDT
Heat from rot.....Saw dust piles will produce heat for years, and if it ignites, it's a bitch to put out.


Link Posted: 12/29/2005 3:05:10 PM EDT
Man, not a single question yet that hasnt been answered by you guys!
It makes a bit more sense now....the piles build heat and the heat steams off the moisture.
The whole spontaneous combustion thing didnt seem possible to me in the past but when explained sensibly it kinda makes sense now.

Thanks guys.
Link Posted: 12/29/2005 3:33:18 PM EDT
Used to drive past a couple of BIG piles of mulch on my way to work.
One day those thigns were smoking away. I asked around at work on one of the volly guys said it started that night. He also said that the DNR was charging him every day that the thing smoldered because they have been after him to get rid of the piles for like 4 months.
These piles are like 30' tall and several hundred feet long.
Link Posted: 12/29/2005 3:40:25 PM EDT

Originally Posted By MNGuns:
Heat from rot.....Saw dust piles will produce heat for years, and if it ignites, it's a bitch to put out.





I recall once some years back a mountain of cow manure caught on fire from spontaneous combustion from the heat of decomposition. Apparently, they didn't turn the mountain with bulldozers often enough. Pissed off a few of their neighbors and, yeah, it was a real bitch to put out. Because the fire comes from inside the pile, you have to tear apart the burning pile.
Link Posted: 12/29/2005 3:44:42 PM EDT
It be hte Garden gnomes smokin itup, dude
Link Posted: 12/29/2005 6:24:04 PM EDT
Neighbor lost their whole barn due to this, spontaneous cumbustion. It was during the second cut of alfalfa, rain was forcast the next day so they decided to bale it up half green, they stored it in their hay loft and half way through they ran out of salt went into town to get more it turned out their boys decided to do a favor and ( put they figgured fifty green bales set aside for outside storage in the loft).
The rest of the bales got stacked on top of them that were salted and about a month and a half later everything was gone.
Link Posted: 12/29/2005 6:30:07 PM EDT
decomposition

If the pile is big enough, it will ignite from the heat. We had a rash of those here in town and we kept having to take the truck down there to hose them down. Finally the Fire Inspector told the land developer that he would have to start stirring the piles with his bulldozer to allow the heat to dissipate, or face a fine.
Link Posted: 12/29/2005 6:37:07 PM EDT
I believe it has to do with the high moisture content breaking down the sugars in vegetation which produces a media that bacteria will thrive, which in turn produce energy in the absense of oxygen. Or something like that.
Link Posted: 12/29/2005 7:46:38 PM EDT
They same reason your bags of grass get real hot setting out by the curb!!!

Fermentation produces heat(Farmers don't put up green bales of hay in thier barn)it will burn your barn down!!! You cut it,rake it then bale it,sometimes let it set in the field before you haul it!!

Bob
Link Posted: 12/29/2005 7:55:15 PM EDT

Originally Posted By Grizzly556:
Neighbor lost their whole barn due to this, spontaneous cumbustion. It was during the second cut of alfalfa, rain was forcast the next day so they decided to bale it up half green, they stored it in their hay loft and half way through they ran out of salt went into town to get more it turned out their boys decided to do a favor and ( put they figgured fifty green bales set aside for outside storage in the loft).
The rest of the bales got stacked on top of them that were salted and about a month and a half later everything was gone.



Yep, green hay + round baler = bad juju
Fella lost about 50 round bales when they caught fire....fire dept had to use a bulldozer to push the bales apart and try to unroll them to put the fire out.
Extension svs used to recommend using perforated pipe stabbed thru the middle of bales to dissipate the heat and speed drying times, but I think they finally figured out its just best to bale dry hay instead.
Link Posted: 12/29/2005 8:07:06 PM EDT
Actually.....it's little hippy mulch munchkins smoking their little hippy mulch munchkin mulch pipes making mulch smoke in those piles. They are likely having a little hippy mulch munchkin mulch smoke in.

But don't go looking for them in those piles of mulch...
Link Posted: 12/29/2005 8:09:28 PM EDT
Pour some gasoline on the mulch pile and let it work its way inside the pile, then light it (from a distance of course), shit will fly everywhere!
Link Posted: 12/30/2005 3:08:01 AM EDT
A couple or three years back in the St Louis area, some people had a house fire caused by spontaneous combustion. They went picking nuts somewhere nearby, and carried them home in a metal pail. The lady put the pail in the garage and placed a (metal) pan over it with a brick on top, to keep their dog from nosing around in it.

The couple left for a short time and came back to find firefighters extinguishing what was left of their garage. The fire dept detirmined that the cause of the fire was that the nuts inside the metal pail had spontaneously ignited.
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