Couple other odd things about this story... Marietta Indiana is located in Shelby County not Crawford County. There is however a Marietta in Crawford County Wisconsin?
Also Harrison County Indiana is not even close to 18 miles away more like 110 miles away. (coincidentally there is also a Harrison County in Wisconsin but it is even further away from Marietta in Wisconsin)
Most likely it is Marietta Indiana and but very odd that the county is wrong and the farmer's account of the dirt is also incorrect (my best guess at this point is reporting mistake) Harrison County is rich in Limestone which may explain the soil difference. I know southern Indiana (bloomington) has a distinct red clay soil that is not even present where I live 1 hour north east.