time the dammer rotates one third of a revolution dumping one dam and continuing to form another application_number US 5170579 A description referring to the drawing there may be seen a series of beds f with furrows between them and dams d in the furrows fig2 shows a different view of the beds f with the dams d it may be seen that rain or water applied by other means to the field will be prevented by the dams d from running down the furrows between the beds f referring to fig3 there may be seen lister 10 attached to tool bar 12 other type plows besides the lister 10 could be attached to the tool bar 12 dammer 14 is pulled behind the tool bar 12 by yoke 16 the yoke forms draft means for pulling the dammer 14 through the field the yoke 16 is connected to the tool bar by horizontal pivot bolt 18 in most situations the yoke 16 will be attached to the shank carrying the plow but in all events the yoke 16 will be pivoted about a horizontal pivot normal to the direction of draft t so that it is free to swing up and down.