The Moldboard Plow (also called Bottom Plow) applies the principle of turning soil used widely in traditional farming.  The plow turns over topsoil, bringing subsoil to the top and burying weeds and previous crops; thereby speeding decomposition.This is an alternative to the tiller and rotary plow attachments for first-time soil breaking.  If used, a pass or two of the tiller will still be needed to prepare a ready-to-plant seedbed.
Because the moldboard plows require significant traction, the tractor needs large wheels and plenty of weight to be productive
http://www.hy-tractors.com