This is what happens when a wing falls off a plane-
http://www.youtube.com/watch?v=m_orQlBpIag
Or-
http://www.youtube.com/watch?v=TBcC8zqNjKk
Or even-
http://www.youtube.com/watch?v=LPbhQS6IljU
Wings = lift, thus, no wings = no lift, and then no lift = falling out of the sky. If one wing falls off, the plane will bank (and pitch) drastically to the side without the wing.
For a plane landing on soft ground at speed, you'd expect to see at least a puff of dirt and/or grass at touch down...the ground remains undisturbed at the "landing site". Not to mention the stresses on the landing struts that somehow remain intact.