Fire hazard

   #1  

oosik

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I have several fields of bunch grass on my 80 acres. I have not mowed them as an effort to slow down wildfires. Reason being - whether mowed or standing, the field grass has not been removed. It's still there.

I see where several say they mow to reduce fire danger. I question that wisdom. If you mow and the cuttings are still there - the fire danger is still there also. Exact same as my fields of bunch grass.

What is your wisdom/opinion on this matter???
 
   #3  

California

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I think grass laying down will absorb more moisture from the soil so it will burn slower.
 
  
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oosik

oosik

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I've only witnessed one wildfire up close and personal. It burned thru uncut and cut wheat fields about the same.

That's probably a good theory also, Calif. If your ground has any moisture at all. Around here - cut green grass - the moisture from the green grass goes into the soil.

The very most important factor in the wildfire I witnessed - the wind. The wind was blowing "fire bombs" up to a quarter mile ahead of the burning front. It easily bridged county roads and disked fire breaks. The wind shifted and gave the firefighters the chance they needed. It was extinguished just 100 yard from my west property line.
 
   #5  

ponytug

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X2 on @bcp's observations. Flattened grass burns more slowly, and cooler than standing grass. It also has shorter flame heights and is less likely to ember "bomb" ahead of the fire line.

BUT! Mowing is itself a big fire risk, especially in areas with rocks. Sparks plus the fan action of the mower can get a fire going pretty quickly. That's why we mostly use cattle to reduce the grass height.

Personally, I only mow if the vegetation is green and wet.

Given your RH, and the time of year, I would be inclined just to disk an area close to you and call it a fire break.

YMMV...

All the best,

Peter
 
  
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oosik

oosik

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That's basically what I've done Peter. I've mowed a large semi-circle around the outer perimeter of the house and outbuildings. Followed by a thorough disking - fuel reduction.

That and recheck my homeowners insurance policy.
 
   #7  

ericm979

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The rule of thumb is that flame height can be up to 3x the height of the vegetation. So 3' grass can get you 9' high flames while 4" of stubble and cut grass lying down would have up to 1' high flames. Fire needs air to burn. When the flammable material is up in the air and has space around it, like standing grass does, the air can get into it as it's burning. So it will burn faster and hotter than the same material lying on the ground.

But yea it's late in the season and risky for mowing.
 
   #8  

ponytug

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FWIW: this is something I found on the CalFire website a long time ago, and then put into a flow chart for my own use. Use at your own discretion, and risk;
Mowing_fire_risk.jpg


All the best,

Peter

P.S. I just looked for this on the CalFire website, and couldn't find it, so it may be outdated advice.
 
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oosik

oosik

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Well - that cut it for me. The only time the RH is over 10% - middle of the night. AND - any time after about 10AM the temps here are certainly over 80F. Besides - any mowing I would be doing after 10AM - I'd turn into a beet red prune. My tractor has a canopy - not my riding mower.

OK - Eric, now that makes sense.

I think I'll just hook up my big 'ol disk set and disk up a fire break up on the high meadow. That will establish a fire break between my big lake and little lake. I could also run up/down the west property line.

Man - I tell you. This country is over prime for a fire. I have NEVER seen the P. pines dropping needles like they are now. Walk out across my "lawns" - the grasshoppers flare up ahead of you like an ocean wave.

Anyhow - Brownie & I are staying cool inside. And thank folks for all the input. It is appreciated.
 

Larry Caldwell

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I know what you mean about humidity. We haven't had dew here in two months. When I'm outside I assume I am sweating, but can't tell because I dry so fast. I'm going through a gallon of water a day, and not peeing anywhere near that much. o_O
 
 
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