All powers and duties concerning approval of appraised timber values, forestry practices and parcels of land from which timber may be sold which are conferred upon the commissioner of natural resources, by sections 282.01 to 282.13, may be delegated by the commissioner to competent forestry field officers of the Natural Resources Department or such approval may be waived at the discretion of the commissioner in such manner as the commissioner shall prescribe shall be sufficient for the purposes of sections 282.01 to 282.13.