The Dodger Stadium field was covered by 5,000 cubic yards of dirt — about 500 dump-truck loads equal to about 1.5 million pounds — to create a track of berms and moguls and jumps for Saturday night’s Monster Energy AMA Supercross Series races, which will be held for the first time at the home of the Dodgers. They also plan a Monster Jam truck event there Feb. 19, so the field will remain covered with Prater’s dirt for about five weeks.