Separating the 10 gold coins needed for the wall construction and paying the summoners and woodworkers, Auren was left with ten gold coins. His successful yield on his farm had also earned him over one gold. But after deducting all the costs of farming and paying Boros, it came down to 65 silver coins.
When Auren asked if Boros would continue farming for him—if he paid the same amount for a normal-sized land—Boros agreed. More than for himself, it was for the villagers requesting Boros to show them the new method that had forced the guy's hand. Somewhere deep down, however, Auren had sensed that Boros's condition had improved a little, and the guy was seriously interested and wanted to know more about all the things Auren had instructed him to do for their farm.
Him paying the guy was just a little incentive. Boros had again started farming—in a much different way than anyone had expected—but it was equally, if not more, effective.