Any person operating a threshing machine, or engaged in the business of threshing and harvesting grain or grain crops, shucking, husking or gathering of corn, either by hand or by machinery, for others, who shall under contract with the owners of such grain or grain crop, or with the mortgagee thereof, thresh, husk and harvest such grain or crop, shall be entitled to a lien thereon from the date of such harvesting, husking or threshing to secure the payment of any amount due for threshing, husking and harvesting, from and after the date of such threshing, husking or harvesting. Such lien shall be preferred to that of any prior security interest or encumbrance.