Here, the township uses Mag cloride on the heaviest traveled roads. At one time, soybean oil was less expensive and just as effective, now it's too spendy (trucking and product). The mag cloride is used to stablize the gravel from high volume traffic use. Without it, the road wouldn't last, it'd break down and move the gravel to the edges/ditch shoulders and become ruttie. The best would be asphalt, but not enough funding for those projects - yet. The mag cloride controls dust also. For those twp residents that want to pay for dust control, they can contact the twp board and request dust control (slightly less product it applied) at the land owners expense. Quite a few do pay for in front of their place. There is an operation out of Mpls the covers most of Mn out of Mpls area (Savage Mn). I looked into it for spraying down a shed floor - it was too spendy to have them do it for me, I felt . . . .

Edit - Thanks to Tom, I stand corrected - It is Magnisuim cloride not calcium