A lien created under section 52-501 shall not attach to such grain, seed, or corn in the hands of an innocent purchaser or dealer in the usual course of trade unless all the notices provided for in such section shall have been given. In the event the threshing, combining, hulling, picking, husking, or shelling was done on rented or leased land, the lien shall not apply to the landlord’s or lessor’s share of the grain, seed, or corn. The lien shall not be assignable.