*** 1/2 EMMYLOU HARRIS, “Red Dirt Girl,” Nonesuch

One reason Harris is arguably the most captivating female artist ever in country music is that she has never felt obliged to stay within the commercial boundaries of country music in searching for material.

The Gram Parsons protegee has recorded lots of country songs over the past 30 years, but she has also explored rock, folk, blues and pop--finding jewels in the works of writers both famous (Bob Dylan, John Fogerty) and unfamiliar to most of her fans (Townes Van Zandt, David Olney).

Through it all, Harris has given us such soulful and affecting work that it has been hard to tell whether her creative strength rested more in her evocative vocals or her uncompromising taste for songs.

That question takes an unexpected turn with “Red Dirt Girl” because Harris, who has written sparingly over the years, wrote or co-wrote 11 of the 12 songs. Harris’ earlier collection of originals, 1985’s “The Ballad of Sally Rose,” seemed like a tentative step compared with the ambition and depth of this collection. In song after song, she conveys the same artistic grace and penetrating observation that she has previously found in the works of other writers.

Though the album isn’t a strict concept, the stark title song serves as a connection point for the sense of isolation and yearning that runs through much of “Red Dirt Girl.” In that song, which was inspired by the film “Boys Don’t Cry,” Harris writes about someone unable to escape from the soul-draining circumstances of her surroundings. Elsewhere in the album, which was produced by Malcolm Burn, Harris explores questions of faith, devotion, obsession and isolation.

The arrangements remain in the experimental, folk-edged style of “Wrecking Ball,” the 1995 album she did with producer Daniel Lanois. This time, though, the textures complement her voice rather than compete with it as they did at times on “Wrecking Ball.”

The only weak spots are the non-Harris tune (Patty Griffin’s “One Big Love” is too slight for this context) and a duet with Dave Matthews that doesn’t really connect emotionally.

Mostly, “Red Dirt Girl” is a major step for Harris, one that moves her into the world of the singer-songwriters with a force that is as welcome as it is surprising.

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Albums are rated on a scale of one star (poor), two stars (fair), three stars (good) and four stars (excellent). The albums will be in stores Tuesday.