Where the Board, in the exercise of its powers under this section, has carried out any soil conservation work on Crown land without any grant or loan made by the Soil Conservation and Rivers Control Council pursuant to the provisions of section 30 of the Soil Conservation and Rivers Control Act 1941, then, notwithstanding any provision of this Act or any other Act, the Board may, as a condition of alienation of the land, require any purchaser, lessee, or licensee to enter into a land improvement agreement, as if the soil conservation work had been carried out by a grant or loan by the Council under the said section 30, with the Catchment Board or Catchment Commission constituted under the Soil Conservation and Rivers Control Act 1941 for the district or area, as the case may be, wherein the land is situated, or with the Waikato Valley Authority constituted under the Waikato Valley Authority Act 1956 where the land is situated in the Waikato Valley as defined under that Act, for the future maintenance of that soil conservation work in such manner and upon such terms and conditions as the Board may require. All the provisions of section 30a of the Soil Conservation and Rivers Control Act 1941 relating to the form of registration and the effect of land improvement agreements, as far as they are applicable and with any necessary modifications, shall apply to any land improvement agreement entered into in accordance with the provisions of this subsection.”