What does Basis Grade mean?
This refers to the minimum specific grade that is listed on a futures contract. Should the deliverable commodity differ from the basis grade it could be subject to a different price than what was agreed to on the futures contract.
Futures Knowledge Explains Basis Grade
As you can imaging with a commodity like wheat, there are differing levels of quality and yield. Some might have too much moisture, grain that is too moist is susceptible to deterioration.