(d) When the water of a canal is supplied for the irrigation of a single crop, the permission to use such water shall be held to continue only until that crop comes to maturity, and to apply only to that crop; but, if it be supplied for irrigating two or more crops to be raised on the same land within the year, such permission shall be held to continue for one year from the commencement of the irrigation, and to apply to such crops only as are matured within that year: