Good but actually Sand is it's own element and if I'm not mistaken, sand users can freely control sand.earth element is one of the five basic elements, it is strong against suiton and weak against raiton.
Doton element can be majorly used for trapping techniques and as defense against most physical attacks.
It can also be used for offensive techniques.
In this technique the user uses his/her chakra to manipulate ground, rock and sand.
I am not sure but the jutsu used by gaara to control the sand is also a doton technique of high level.