What kind of dirt is used in a Major League baseball infield?
The "dirt" we see isn't really what I would call dirt. A baseball infield is made up of a special mixture of sand, silt, and clay. (Silt is a natural material halfway between sand and clay as far as particle size is concerned.) There doesn't seem to be any one central source and depends more of the likings of the local groundskeepers. At Fenway Park, they mix in some ground up kitty-litter type stuff to give the infield "dirt" a redder color. Our local AA minor league park has artificial "dirt" made up of ground up automobile tires. Low maintenance and good drainage were what they were looking for around here!