We went to the Phoenix Supercross race a couple of weeks ago. What fun! I watched the tractors groom the track almost as intently as I watched the race. I have a little Ford tractor with a loader and, you guessed it, built a track and some jumps for the boys. But like everything out here in Adobe land, what little moisture in the ground quickly dried out and the dust got very thick fast. Out come the sprinklers. Riding out west can be very dusty anyway, but a track really dries out fast.
.....But there was NO dust, not a smidge, at the Supercross race. Hmmm, what are they doing? Sure, there's a water truck, which I never saw them use. I'm thinking they must have some additive in the soil to retain moisture and keep the dust in the dirt. I mean the roosts would come off those rear wheels and fall straight to the ground. I doubt I will actually do anything, I have less than 10 dollars worth of diesel in this track, and a hose bib is right there, but I would like to know. Anybody? [img]i/expressions/face-icon-small-confused.gif[/img]

 

They don't use local dirt. They actually truck in the dirt and it is primarily clay based. That ensures it holds moisture as well as shape for jumps and berms. Leave that dirt uncovered, outside, here in the southwest, and you would have MX track shaped pottery[at least in the summer]in less than a month.

 

There's another little thing that I do to my track, my track has black here, brown dirt there, clay over there, and a sandy section. the brown dirt section which is about half the track is dusty, well was dusty, I mixed in wood chips with the dirt using a disc behind my tractor for a month, adding more each week, it creates loam and holds moisture so no more dust, even after 2 weeks without rain it did not get dusty at my track. Eventually i'll have to chip more but hey thats part of the game.

 

buy alot of bags of potting soil [img]i/expressions/face-icon-small-happy.gif[/img]

 

These guys are right. They haul that dirt from SX to SX, and it's always moist. I sure wish I could have one of those tracks to play on [img]i/expressions/face-icon-small-smile.gif[/img]

 

forlix- we have some sucess mixing dirt from different parts of our property. Last summer when i built my track, after 3 laps you could not see where you were headed. This track is slightly larger than a half mile. We moved in excess of 3000 yards of material. I am about to rework parts of it, add another 3000 yds of dirt. I am going to hook a irragation system to it.

 

I posted this over in Yamaha land where several mentioned Calcium Chloride. I had heard of this before. It would certainly explain why they would truck the dirt, and/or stash it locally till they needed.
I bet this dirt is worked out, like, rocket science. Every component is calculated from sand and clay content to additives and moisture content.

 

I used to work in construction before computers (I drove a water truck) I can tell you there is A LOT more technology in dirt than you could ever imagine. I'm sure the dirt they use for the races that is dustless has been tested in the lab as fourlix suggested, where they figure out the maximum compaction of the dirt and the exact percentage of water content to make it the most compact. They have guys come out and stick a radioactive rod in the ground that tests for compactness/water content. Always seemed like a lot of work since it's just 'dirt' but the difference was easy to see.

 

I fyou want to have your ground tested for free, you could always volunteer to loan your land to the Local High School's Agriculture Class for soil judging practice.