Section 13. Enhancement of rent when productive power of holding increased by landlord.

Notwithstanding anything in the record-of-rights, but subject to any contract in writing between the parties, the rent payable in money by any tenant may, on the application of his landlord, be enhanced by a Revenue-officer on the ground that an improvement has been made since the present rent was fixed and in accordance with this Act by or at the expense of the landlord whereby the productive power of the holding has been increased.