Steve Earle’s debt to cult singer-songwriter Townes Van Zandt is immeasurable. Van Zandt championed Earle during his struggling-artist years, and Earle even named one of his sons after the troubled troubadour (who drank and drugged himself to death when he was 52). In a way, Earle’s entire career has been a tribute to Van Zandt — from his plaintive storytelling to his turbulent personal history. But Townes is his first album-length tribute, a 15-track survey of Van Zandt’s finest compositions that starts with a low-key version of his best-known song, “Pancho and Lefty,” a country hit Van Zandt wrote for Willie Nelson and Merle Haggard in the ’80s. Throughout, Earle shifts between solo acoustic retellings and band-assisted electric fury, sticking pretty close to Van Zandt’s templates. He’s at his best — like on the meditative “No Place to Fall” and “To Live Is to Fly” — when Van Zandt was at his best.