Question on hay fires?

Seen down the line talk of hay smoking and burning. .. It has been many years since I halled hay. But know next year I will be buy some and storing it to. Want to get some cattle to raise here.
So green hay will catch fire if baled to soon and not dry? What about storing it? Are round bales better then square bales? What causes the heat build up in hay?
Thanks for any replies. Knowledge here is important for me to know on hay. Thanks again

What you are hearing about is called spontaneous combustion by fire safety types. Simply stated, when the heat in a material exceeds the material's ignition point and sufficient oxygen (air) is present the material will begin to burn. Different materials have very different ignition points. In the natural world a simple rule of thumb says the denser a material is the more heat it requires to burn, hence, a single match will not start a 2x4 burning but it will ignite a bale of hay because the hay is fine grass and/or alfalfa. In spontaneous ignition the heat is generated in the same manner as in sewage systems - natural decomposition of biological material by bacteria and fungi (fermentation). When hay is baled damp more organisms can grow generating more heat inside the bale thus raising the temperature inside the bale quicker than heat can be dissipated to the outside. When that heat exceeds the ignition point of the hay it begins to burn. Dry hay does not support as much fermentation so less heat is generated inside the bales. The process is the same regardless of the bale shape or size. Larger bales dissipate heat slower than small bales BUT if small bales are stacked tight, as in a shed or barn, they will hold as much heat as larger bales. Hay fires are hot, dirty and very time/water consuming to extinguish - be careful to buy dry hay!!!

search engine "spontaneous combustion in hay"
will be easier than trying to explain here.

If you're buying out of someone's barn or shed, there wouldn't be any concerns if it were me. Same thing if buying from a guy who does lots of hay and you buy it right of their feild. Round bales can be stored outside so as long as they are you won't risk burning down your shed or barn.

Most guys who put up hay are good about having the correct moisture, but even the best of guys can be rushed by weather.

Donovan from Wisconsin

I've also heard of placing a layer of salt between each layer of bales. Don't know why, but that's what the old-timers always said. It must slow the fermentation process.

We usually have groups of smart-A$$ kids that go around lighting rows of round bales on fire. Nothing like getting roused out of bed at 2:00AM to put out one of these fires.

Along with all that was said here if you stack green wet bales next to dry bales you increase the chance of fire.

That is what happened here.

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Hay was baled a little to green and stacked next to old dry bales. The green ones got hot and ignitedthe dry ones. This happened 6 weeks after the hay was stacked.

Gary

Just don't put it up on Sunday.

A buddy of mine had a stack get hot once, and his father swore it was because it had been put up on Sunday.

I've been making 5X6 round bales for 22 years. I store my netwraped bales outside in a row end to end. I always try to have the correct moisture when I bale but it is not always possible. This year I baled a good number on the tough side. They will heat and you can smell them for a few days but I have never had one burn. Now if I stored them in a shed piled up they would for sure burn. If hay has been stored for some time and is cool there is little to no chance of fire. Its the recently baled stuff that could burn if its to wet. Once it goes thru its heat cycle its safe.

I've also heard of placing a layer of salt between each layer of bales. Don't know why, but that's what the old-timers always said. It must slow the fermentation process.

We usually have groups of smart-A$$ kids that go around lighting rows of round bales on fire. Nothing like getting roused out of bed at 2:00AM to put out one of these fires.

Cody gives you a good explanation of the process. Heating is part of curing. Microbes continue to consume oxygen and plant nutrients until the moisture content drops below the point they can reproduce. Just like with corn or soybeans. Put them in the bin too hot and they will spoil. The heating from the hay can ignite dry hay either in the same bale or adjoining bales. Same can happen with hayledge if the silo isnt airtight. Makes a nasty silo fire.

Density makes it worse, since moisture and heat have a harder time getting out of the bale. Thats why we want hay for round bales DRIER than we want hay for small square bales at baling. Large square bales have a higher density still. With round bales, you can get away from the fire risk by storing outside where heat can dissipate. Inside a barn tightly stacked round bales are a great fire hazard if they are too wet going in. A lesser risk is given the same moisture a barn stored stacked round bale can mold when a loosely stacked small square in the same barn wont.

Don't know about putting salt in between rows of bales, but around here, back in the days when everyone stacked loose hay, the old-timers claimed that if you had to stack wet or otherwise not real good hay, to throw a handfull of rock salt on the stack with each load of hay going on it. Said that would make the difference in whether the cows would willingly eat it or just turn their noses up at it. Could be that the salt helped get rid of the moisture?

The salt absorbs moisture from the hay.

That is why CaCl is used for dust control. It absorbs moisture from the air and keeps the dust slightly moist. If you spread it too thick you can actually get water puddles to form.

One additional thought: Be careful openning a hay stack which is warm. As long as you can handle the bales you are probably OK. If the bales become too hot to handle without gloves STOP and call help. If you actually see a hay pile emitting smoke DO NOT touch it - call your local fire department and let them guide you through breaking down the pile after they have a pumper truck and hoses on site. Realize a smoking pile is already hot enough to burn and only lacks oxygen somewhere inside to accelerate the burning. Openning the pile allows air in and could allow the pile to flare into a ball of flames enveloping your equipment and you. Be careful and stay alive.

Well I think I am a bit wiser having all this information at hand. Again I thank you all.