Sunlight is the key ingredient in maximizing fruit production. Early morning sun is really important to dry the dew from the plants,  thereby reducing the incidence of disease.  So choose a  site on your property that is in the sun most of the day.  Otherwise,  expect reduced performance from your trees. Well-drained soil is more important than soil fertility.  Avoid soils that the water is still standing  24  hours after a   good rain.  It is in these areas that the roots will die from a  lack of oxygen.  If you are forced to plant in these areas you will need to plant on raised or terraced beds. Lastly do not plant  Apple  Trees in high alkaline soils.    Apples develop many minor element problems when planted on high PH soils.