A box blade assembly for attachment to earth moving vehicles has a rotatable semi-cylindrical closure blade. The box blade includes a pair of spaced parallel side walls, an open front, top, and bottom, and a rear wall having a depending scraper blade attached to the bottom edge thereof. A semi-cylindrical, transversely-extending, closure blade is rotatably mounted on the side walls of the box blade. A fluid-operated cylinder rotates the closure blade from an open position, with the bottom of the box blade open, to a closed position abutting the rear wall and scraper blade enclosing the bottom of the box blade. A vehicle pulls the box blade along the surface of the ground with the scraper blade scraping dirt and confining it within the side and rear walls. The closure blade when rotated to the closed position extends underneath the collected dirt so that it can be lifted with the box blade for transporting to another location. When the closure blade is rotated to the open position, the dirt is dumped from the bottom of the box blade.