Except as provided in this chapter, a deed of trust is subject to all laws relating to mortgages on real property. A deed conveying real property to a trustee in trust to secure the performance of an obligation of the grantor or another to the beneficiary may be foreclosed by trustee's sale. The county auditor shall record the deed as a mortgage and shall index the name of the grantor as mortgagor and the names of the trustee and beneficiary as mortgagee. No person, corporation or association may be both trustee and beneficiary under the same deed of trust: PROVIDED, That any agency of the United States government may be both trustee and beneficiary under the same deed of trust. A deed of trust conveying real property that is used principally for agricultural purposes may be foreclosed as a mortgage. Pursuant to *RCW
62A.9-501(4), when a deed of trust encumbers both real and personal property, the trustee is authorized to sell all or any portion of the grantor's interest in that real and personal property at a trustee's sale.