from the Online Etymology Dictionary

turf (n.)
O.E. turf, tyrf "slab of soil and grass," also "surface of grassland," from P.Gmc. *turb- (cf. O.N. torf, Dan. tørv, O.Fris. turf, O.H.G. zurba, Ger. Torf), from PIE base *drbh- (cf. Skt. darbhah "tuft of grass"). Fr. tourbe "turf" is a Gmc. loan-word. The O.E. plural was identical with the singluar, but in M.E. turves sometimes was used. Slang meaning "territory claimed by a gang" is attested from 1953 in Brooklyn, N.Y.; earlier it had a jive talk sense of "the street, the sidewalk" (1930s), which is attested in hobo use from 1899, and before that "the work and venue of a prostitute" (1860). The verb is attested from c.1430, originally "to cover (ground) with turf." Turf war is recorded from 1950s.