Preferable to mix old gasoline with diesel to start fires with..2 parts diesel to one part gasoline in high humidity. Low humidity and dry conditions, increase the ratio to 3:1. The gasoline ignites the diesel and diesel will generate longer lasting heat to really get damp wood burning, while the volatiles in gasoline (even stale gasoline) flash off in seconds.
I've used this safely in drip torches for controlled burns.
I agree with the lower volatility and prolonged heat output of diesel & kerosene (they are basically the same thing) and I have used both in the past. But I'm afraid I have no machinery here that requires/uses either, so I don't have any readily available, and don't plan to buy any specifically for burning brush piles.
I really ought to get to my burn pile .... but I've never done one and that bugger is getting awful big. If I do it in the winter when there is snow on the ground I don't need a permit.
If I do it in the winter when there is snow on the ground I don't have a hose for "just in case".
@Bruce just be sure the prevailing wind is blowing away from any structures....and light the down wind side of the pile....that way the wind won't push the flames to more fuel and flare up on ya....once it gets half-way burned, then what is left will be blowing on fuel depleted ground and less likely to get out of control. I don't like to burn leaves or grass on a big pile unless it is covered with branches to hold the embers down until they are burned. I always use a rake and a shovel....not a leaf rake, but a heavier garden rake it can help spread things out and the shovel can smother flames fairly quickly and shovel dirt on the pile if needed. If the pile is really huge, then pull some off the pile and lite it down wind and let it burn to the bigger pile....you'll have better control of it....if ya need a little fuel to get it started, use rubbing alcohol...it doesn't flare up and it doesn't stay in the soil...it burns clean....
humidity level is way more important than wind. I burned about 22 big burn piles in '08-09. Big as a house some of them.
The aftermath
The National and Texas Forest Service does prescribed burns frequently here, and always watch for a high humidity day to do it. They burn thousands of acres at a time and as far as I know, have never had one get out of control in this or the adjoining counties.
Big burn piles, make their own wind. If you don't think so, light one up at night...you can see the glowing embers go hundreds of feet into the air and drift off to the sides of the pile in the lightest of breeze. But, if humidity is high, they go out before they hit the ground and even if they hit the ground, the likelihood of them being able to catch grass on fire is minimal.