There was a total of $23 million of farmsand rural real estate for sale in Decatur County, Indiana, recently on Land.com. The total acreage of all Decatur County farms and rural land for sale was approximately 1,000 acres. Decatur County ranks 64th in the Hoosier?State for the total number of acres of land currently advertised for sale. Greensburg featured the most land for sale. Decatur County is the 64th largest county (373 square miles) in Indiana. It's located in the South Central Indiana region of the state.