It's too late for an amendment. You will need to make the correction on Form 3115.
Unfortunately the depreciation recapture is "allowed or allowable" meaning even if you never depreciated it, you would still have to recapture the depreciation. Depreciation taken would be on line 18 of Schedule E.
One solution is to elect an accounting method change and file a Form 3115 in the current year and take the prior depreciation as a section 481(a) adjustment. [land value is separated, land is not depreciated]
Below are the IRS links related to the change in accounting method. TurboTax does not have that form.
May be these will help
Form 3115, Application for Change in Accounting Method
http://www.irs.gov/uac/Form-3115,-Application-for-Change-in-Accounting-Method
Instructions for Form 3115 (03/2012)
http://www.irs.gov/instructions/i3115/index.html
Form 3115,
http://www.irs.gov/file_source/pub/irs-pdf/f3115.pdf
