Any person furnishing labor, equipment, material, or supplies used or consumed for the improvement of real property, under a contract with the owner or with the trustee, agent or spouse of the owner, shall have a lien upon the property for the labor, equipment, material or supplies furnished at the site of the property subject to the lien, and for the cost of transporting the same. The lien shall be preferred to all other liens or encumbrances which are subsequent to the commencement of the furnishing of such labor, equipment, material or supplies by such claimant at the site of the property subject to the lien. When two or more such contracts are entered into applicable to the same improvement, the liens of all claimants shall be similarly preferred to the date of the earliest unsatisfied lien of any of them. If an earlier unsatisfied lien is paid in full or otherwise discharged, the commencement date for all claimants shall be the date of the next earliest unsatisfied lien.