You can never file MFJ on a 1040NR.  As Susan says, if the land was jointly owned, file 2 separate returns.  If this is the case, taxes should have been withheld from both under FIRPTA.

What Susan meant is that joint filing may be elected but at least one of the spouses must be at least a dual-status resident (either by substantial presence test or another election).  The result is that both will be treated as full year residents and a 1040 will need to be filed to report worldwide income (although there are other ways to alleviate double taxation).  This involves tax planning/analysis and is not be applicable or beneficial to all.