Bava Metzia 104 - Calamities in the Field and Laymen's Contracts

If one leased a field from his fellow, and it had a stream from which it could be conveniently watered, or a tree which produced fruit without requiring much work - the field thus commanding a higher rent - and the spring dried up or the tree was felled, he may not deduct anything from his rent in compensation for his loss. If he mentioned that his reason for renting the fields was the river or the tree - then he may deduct.
If a sharecropper leased a field and left it fallow, they assess how much it was fit to yield, and he must give that amount, because a layman’s contract usually said, "If I leave it fallow and do not work it properly, I will pay according to the best."