What is "to plow in"

Plow \Plow\, Plough \Plough\, v. t. [imp. & p. p. Plowed (ploud) or Ploughed; p. pr. & vb. n. Plowing or Ploughing.]

1. To turn up, break up, or trench, with a plow; to till with, or as with, a plow; as, to plow the ground; to plow a field.

2. To furrow; to make furrows, grooves, or ridges in; to run through, as in sailing.

   Let patient Octavia plow thy visage up With her prepared nails.
   --Shak.

   With speed we plow the watery way.
   --Pope.

3. (Bookbinding) To trim, or shave off the edges of, as a book or paper, with a plow. See Plow, n., 5.

4. (Joinery) To cut a groove in, as in a plank, or the edge of a board; especially, a rectangular groove to receive the end of a shelf or tread, the edge of a panel, a tongue, etc.

   To plow in, to cover by plowing; as, to plow in wheat.

   To plow up, to turn out of the ground by plowing.