"soft or marshy place," 1530s, of unknown origin. Also as a verb, "to become soaked; to soak" (mid-15c.), perhaps related to soak (v.) or from or related to similar words in Scandinavian.
Online Etymology Dictionary, © 2010 Douglas Harper
Examples from the Web for sog
Las' summeh's sun neveh fazed it 'cept to sog it down all the mo' solid.Connie Morgan in Alaska
James B. Hendryx