Best to stick with a good Accountant for this one. There's a lot of variables with such a broad question, however, in general if the land was purchased as an investment then the interest can be used as a tax deduction, yes.
We know investors who buy land and sit on it for years ... actually use it as farm land until urban sprawl catches up to it and then they sub-divide and build on it.
Again, for this one, best to double check with your Accountant but our feeling and experience tells us that if you're using it as an investment then you'll be able to write off the interest on the mortgage.
