From a strictly tax viewpoint, I see very little that would be gained by treating the vacant land as a business asset. It is not depreciable and there is no associated loan that would carry tax deductible interest. Your only reasonable tax deduction would be real estate taxes, which I expect are minimal on an acre of vacant land.
Departing from tax considerations, I would urge you to speak with your legal advisor and insurance agent, if you have not already done so, to be certain that your business and you, personally, are protected from any liability that might arise from your use of the land (injury to workers or visitors, etc.).
