Despite having three songwriters, the Drive-By Truckers have made some remarkably cohesive music. But while songs by Patterson Hood and Mike Cooley are compelling, Jason Isbell's tunes cut to the core. The tunesmith left his indelible stamp on tracks such as "Goddamn Lonely Love" and "Outfit," in which he channels the spirit of "Simple Man" for the iPod generation. Earlier this year, Isbell split with the Truckers to focus on the outstanding material he's been working on for the past four years. The resulting solo debut, Sirens of the Ditch, is filled with his irresistible Southern charm and guitar-rock sensibilities, from the swampy, come-hither groove of "Try" to the easygoing, soul-kissed shuffle of "Hurricanes and Hand Grenades." The main draw, however, is the inscrutable sincerity in his voice on songs like "Dress Blues" — a wartime elegy to a schoolmate that avoids jingoistic grandstanding and partisan fist-shaking and simply focuses on the underlying humanity — and "Grown," in which he thoughtfully recalls a momentous coming-of-age crush. As expected, Isbell delivers the goods on Ditch.