For anyone considering planting an apple orchard, these two websites give good info:

http://www.omafra.gov.on.ca/english/crops/facts/apple_fert.htm

http://aggie-horticulture.tamu.edu/extension/homefruit/apple/apple.html

In summary,

-Drainage is key; planting on raised terraces can be a good idea.

-For apple trees, pH of soil needs to be between 5 and 6.5.

-Ripening season ranges from June to October. Note that apple varieties that ripen early cannot be preserved for more than 2 to 3 weeks even in cold storage.