(M480) The tenant, of course, was bound to cultivate the land. The duties which fell to his share were “to plough, harrow, weed, irrigate, drive off birds,”(507) but these duties are but rarely stipulated. The Code protects the tenant, however,(508) from any unfair compulsion in the matter, so long as the landlord gets his fair rent. (M481) Fields were also let at a fixed rent, usually payable in kind. The contracts of the First Dynasty of Babylon give a large number of examples of this sort. The kinds of field are distinguished as _AB-SIN_, or _šerû_, and _KI-DAN_. The average rent for the former was eight _GUR_ of corn per _GAN_; of the latter, eighteen _GUR_ per _GAN_. The former class may include land with corn standing upon it, or simply corn-land; the latter land as yet unbroken, or fallow. The latter class seems to have been much more fertile. This rent later became more fixed because the average yield per area was set down in the lease and the yield in corn was estimated in money according to the ordinary value of corn. Thus the rent is stated to be so much money. (M482) Land was often let to reclaim, or plant. The Code lays down as law what was evidently a common practice. In the case of waste land given to be reclaimed the tenant was rent free for three whole years. In the fourth year he paid a fixed rent in corn, ten _GUR_ per _GAN_.(509) Land let to be turned into a garden was rent free for four years. In the fifth year the tenant shared the produce equally with the landlord.(510) Contracts illustrating this form of lease are quite common in the time of the First Dynasty of Babylon. (M483) Freedom from various obligations might be granted by royal charter. In fact, it is from these charters that we know of the existence of the obligations for the most part. The land so freed was called _zakû_. Land sold is often said to be _zakû_, and we may suppose it was so because it had once been freed by charter. But this is not quite certain. The charter was granted to a person and his heirs. Doubtless, as long as they held it, it would be free, but it is not clear that they could sell it as freed forever. But we only know that some land was free. On whom then fell the obligations? So far as they were due to the king, they may have been abolished, but such obligations as repairs of the canal banks must surely have been taken up by others. If not, the granting of charters must have been a fruitful source of trouble and distress to the land.