Baseball Field (1864)

“…. for be it known to all far and wide that the base ball field, like that of the cricket ground, is one of the most democratic institutions of the land ….” Brooklyn Daily Eagle, August 17, 1864, p3

Previous earliest use (Dickson Baseball Dictionary, 3rd edition, 2009):
1874. “A base ball field.” Henry Chadwick, Chadwick’s Base Ball Manual (OED)