I pressume you mean a Tonne ???
If so is it not that a yard is a linear measurment , whereas a tonne is a weight measurment, so how can you convert the two different measurments ....
Loose soil weighs about 1500Kg per cubic metre, compacted about 2000Kg per cubic metre. A cubic yard is about 0.85 of a cubic metre.
So for loose soil the answer is about 0.8 cubic yds per tonne.