Farmers Co-operative Association v. Cole, 239 N.W.2d 808 (N.D. 1976). Under Utah law, an agreement to secure an obligation with real property must be in writing because it creates an interest in real property. Utah Code Ann. ยง 25-5-1 (1984); Jackson v. Dallin, 47 Utah 312, 314, 152 P. 341, 342 (1915). Therefore, evidence of a course of dealing or of industry usage and custom is not admissible to show that real property used to secure one obligation pursuant to a trust deed is also meant to secure another obligation.