You’ll order soil by the cubic yard. To estimate the amount, try this: Length x Width x Average height / 27 = Cubic yards Multiply cubic yards by 1.3 to account for soil compaction. To get the average height, figure half the height of your rollers and berms. For example: 150ft x 4ft x 1ft / 27 = 22 cubic yards 22 x 1.3 = 29 cubic yards Get more than you think you’ll need. You’ll find a use for it.
If you buy dirt Bring in some good topsoil. It’s easy to work with, sets up a great riding surface and drains well. Topsoil or “loam” is a combination of sand, silt, clay and organic matter. Most loam has a pretty even mix of these materials. Clay loam has a higher proportion of clay, and it tends to pack best (and make the best tracks). SO: When you order dirt, ask for clay loam or topsoil with some clay mixed in.