if I could give you some advice......
I would sprinkle on the "dirt" then once you get solid coverage spray "dirt" with a 50/50 mix of water and white glue until the "dirt" is soaked and then let dry, or use Woodland Scenics Cement to stick the "dirt" down, it's a liquid already pre-mixed and ready for the spray bottle, if you rely on just the white glue smeared on the wood base you wont get a good, full, solid coverage...
If you had something else in mind tho, then forget what I just typed...