From Toadwater Guide
Sand is the basic terrain in Toadwater.
When stepped on using a personal staff, it wears down 0.001 points on the used staff.
Trees can be planted on it, it can be fertilized, fences can be placed on it (outside of newbie world)... basically everything in Toadwater has sand under it.
Types of sand
"Wait.. there are multiple types of sand? No, I don't think so. You must just be crazy."
Wrong. There really are two kinds of sand, though there is just a subtle difference.
<-- Normal sand, found outside of Newbie and Cloud World.
<-- Newbie/Cloud World sand. If it's a newbie world, fences cannot be placed on it, nor can roads.