What is the agreement between Abner Snopes and Major de Spain?

In William Faulkner's "Barn Burning," Abner is supposed to farm the major's land and grow crops, then presumably give a set percentage of the proceeds to the major.  Abner and his family stay on the major's property and live in the shack provided for them. 

After Abner dirties the major's rug, he is supposed to clean it for the major, although this agreement is only inferred by the reader since we don't hear the conversation. 

Of course, before Abner can grow the crops, he ruins the rug by having his daughters clean it with lye, which destroys the rug.

Finally, the justice of the peace rules in the court case brought by Abner himself that Abner should pay the major ten bushels of corn to replace the ruined rug once the crop is harvested.  Instead, Abner decides to burn his barn.