On the 1929 recording of "The Homestead on the Farm," Sara Carter sings forlornly of homesickness. There's a stark beauty in her voice, as if all the excess paint and ornamentation had been pared back to the original rough hewn wood. When she is joined by her husband A. P. Carter's low harmony vocal and her sister-in-law Maybelle Carter's high harmony, the sense of close belonging and unaffected dignity are so strong that you can almost, as the lyrics put it: "Hear the cattle lowing in the lane. /You could almost see the fields of bluegress green. /You could almost hear them cry/As they kissed their boy goodbye."

The songs were recorded by the Original Carter Family in 1927-29 and form the hearf of the recorded country music tradition. The best of those songs have been collected in a splendid new reissue, "The Original Carter Family; Legendary Performers, Vol. I" (RCA CMPM1-2763). Fifty years later, those songs still exert a strong influence on two of today's leading country singers, Emmy Lou Harris and Dolly Parton.

After years of seeking a way out of traditionless suburbia, Harris has finally reached that core of country tradition. On "Blue Kentucky Girl" (Warner Brothers BSK 3318), her new album and bset so far, her willowy voice sounds firmly rooted for the first time.

Harris' model, friend and occasional singing partner, Dolly Parton, didn't have to seek out that tradition. She grew up with it. In time she contributed several songs that stand up to the best of the Carter Family output. But recently Parton have moved in the opposite direction from Harris: away from the limits of traditional and toward greater musical options. On her new album, "Great Balls of Fire" (RCA AHL1-3361), she has broken with her past but without complete success. She still hasn't found her future.

Like tradition in any field, country music tradition can be restricting as well as nourishing. The rhythm seldom varies; the chords seldom leave the majors; the melody seldom strays from its initial course; the lyrics seldom depart from familiar romantic and family fare.

What the confines of country tradition can provide is a focus for incredibly rich ballad singing. That's exactly what Harris produces on her new record. After vacillating for years between California soft-rock and Kentucky traditions, she has finally made a clear choice for the latter. She has gone beyond the paint and ornamentation of current Nashville country to an older heritage. She sounds more like Sara Carter than Linda Ronstadt or Tammy Wynette.

Harris is probably the best harmony singer in American pop music, judging by her work behind Bob Dylan, Neil Young and Gram Parsons. She has an unerring instinct for surrounding a lead singer with velvety shadows. As a lead singer, however, she usually plays it too safe. Without someone to react to, she sticks to the predictable middle.

"Blue Kentucky Girl" is so good, because Harris chooses rich country melodies and sings every song but one as a duet or three-part harmony. She shares Jean Ritchie's "Sorrow in the Wind" with "The White Girls," Sharon Hicks and Cheryl Warren. The three join from the start to create the soft breeze of the rural lament. Harris pushes the harmonies to stronger and stronger gusts of aching sadness.

Her old Washington partner, Fayssoux Starling, and her brilliant fiddler, Ricky Skaggs, sing with Harris on "They'll Never Take His Love From Me" to reach back into the Hank Williams sound. Then she transforms the Drifters' 1960 rock'n'roll hit, "Save the Last Dance for Me," into a courtly number with bluegrass mandolin and fiddle picking and her own twangy vocal.

The most popular song on the album is likely to be "Even Cowgirls Get the Blues." written by Rodney Crowell after Tom Robbins' novel. The track has been salvaged from the planned and apparently abandoned trio album by Harris, Parton and Ronstadt, but the three don't catch fire on the song till the final scat vocal tag with their high, gliding "oohs."

The best track on the record is Harris' duet with Don Everly on the Louvin Brothers' gorgeous love, "Everytime You Leave." The wide contrast between Harris' breathy voice and Everly's solid male voice allows Harris room for her most imaginative responses.

With the possible exception of Willie Nelson, Dolly Parton is the most talented songwriter and performer in country music - so talented that her new album is enjoyable despite her poorly chosen material. Parton's best moments in the past have come from her own compositions. On "Great Balls of Fire," however, she has penned only four of the 10 songs and those four are far below her best.

One of them, "Sandy's Song," epitomizes Parton's worst tendencies toward sentimental kitsch. Her version of the Beatles' "Help!" so closely copies the original that it seems redundant. And Carole Bayer Sager's "You're the Only One" is the kind of pop fluff Parton is better off avoiding.

Despite these shortcomings, Parton uses her acrobatic soprano voice in new ways that justify her attempts to branch out beyond traditional country. On her own "Down," she matches her trembling country voice with Bill Payne's rhythm & blues organ. The result is an odd kind of soul music, with Parton proving how softly one can sing and still swing. Her voice glides through three tiers in the "sweet" of "Sweet Summer Lovin'" with all the wholesome pleasure of frolicking in a haystack.

Her most surprising performance is "Great Balls of Fire," the Jerry Lewis standard. When she sings "Goodness! Gracious!?" she squeals with real surprise. Her innocent delight is much different from Lewis' bragging version. Parton sighs, catches her throat and shouts excitedly as if she were a teen-age gal who just discovered boys.

Her best performance, though, is her most traditional. In "Almost in Love," a daughter tells her mother that she is falling in love and may soon move out. In a remarkable tour de force, Parton Communicates both the giddy excitement of the love and the resigned regret of the leaving.

Both Harris' and Parton's albums underscore the importance of a tradition as represented by the "Original Carter Family." A great deal of the power in any song comes from all the songs that have preceded it. As Harris has learned, one has to delve deeply into tradition to share in that power. But once the connection is established a singer must work to extend the direction of that tradition or risk stagnation. Parton, whose earlier songs are already a part of the country music heritage, is still trying to figure out which way she'll go next.