A wheat farmer is converting to corn because he believes that corn is a more lucrative crop. It is not feasible for him to convert all his acreage to corn at once. He is farming 300 acres of corn in the current year and is increasing that number by 50 acres per year. As he becomes more experienced in growing corn, his output increases. He currently harvests 140 bushels of corn per acre, but the yield is increasing by 4 bushels per acre per year. When both the increasing acreage and the increasing yield are considered, how rapidly is the total number of bushels of corn currently increasing?