Is Capital Gains Tax Owed on This Sale?

[Edward Stephens]

My father and other members of our family owned a farm.  Upon my father's passing in 2007, I inherited his portion of that farm.  After 7 years of being a partial owner of the farm, our family decided to sell the entire acreage. 

My accountant (CPA) suspects I may owe taxes due to the sale of this land, specifically capital gains taxes.  He has advised me to get an appraisal to determine the land's value at the time of inheritance (2007).  He believes I may own a capital gains tax on the difference between the 2007 appraised value of the land and the price I sold it for in 2013.

Does anyone have a definitive answer on whether I'm liable for taxes on this transaction?