ON RECORD EMMYLOU HARRIS - Blue Kentucky Girl, Warner Bros, BSK 3318. JOHN STEWART - Bombs Away Dream Babies, RSO RS-1-3051. ON STAGE EMMYLOU HARRIS - At Constitution Hall, May 30 at 8 p.m. Tickets $7.50 and $8.50.

EMMYLOU HARRIS is a countrymusic crusader. Remember, this is the woman who never blinked when invited to sing backup for Bob Dylan, but who was tongue-tied and butterflied the first time she met George Jones.

Having discovered that her melancholy voice - with that classic country throb - can sell even the purest traditional country songs to her ordinarily rockier audience, Emmylou has set out to convert the heathen to the joys of Merle Haggard and Billy Sherrill and the Louvin Brothers. Album by album, she has leaned more confidently toward traditional country material, until now she has released an album on which even the temperate California country-rock numbers sound as if they came straight off the Opry.

"Blue Kentucky Girl" is a potentially fine album marred by conviction - a combination that, let run riot, transforms art into propaganda. Every song on the album is wonderful and wistful and sung wisely, but they are set to the same metronome, and the overall effect is of exactly that eternal strum -strum-strum -strum guitar drone that used to turn the more "sophisticated" city audiences away from country music. Even in Nashville, musicians know that a little tradition goes a long way.

The deliberately naive production mix, which reproduces rather rawly the whine and swish of Harris's guitar playing, works both for and against her. There's a refreshing reality about it, as if she were back singing at the Cellar Door; on the other hand, given her decision to go back to a primitive style of arrangement, a less rigid production might have alleviated the monotony.

Taken one at a time, the songs are acceptable, although several seem to be marginal choices. Willie Nelson's "Sister's Coming Home," with its hopscotch rhythm, is perhaps the most interesting cut. Rodney Crowell's "Even Cowgirls Get the Blues," given the allusion to Tom Robbins' bestseller, is predictable but no unpleasant. Astonishingly, Harris' rendition of mentor/lover Gram Parson's "Hickory Wind" is reverential to the point of being lugubrious.

As always, her enunciation is so blessedly clear that you don't need the lyrics on the inner sleeve except for the fun of it. What is worth noting on the sleeve are the musicians and singers involved in "Blue Kentucky Girl" - Linda Ronstadt and Dolly Parton (together on "Even Cowgirls," a cut rescued from the aborted sessions for their trio album), Tanya Tucker, Don Everly and Fayssoux Starling; Glen Hardin, Crowell, James Burton, Albert Lee, Bull Payne, Hank DeVito, Ricky Skaggs and "producer-director" Brian Ahern, among others.

What Harris needs to do is decide whether she is fish or fowl: Alabama country girl or California country rocker.The fence she's stradding now is plumb full of critical splinters.

THE PRODUCTION on John Stewart's "Bombs Away Dream Babies" is also spare, but so prominent that it brands every cut on the album. Lindsey Buckingham produced, he and Steve Nicks supply background vocals and he plays guitar on six of 10 songs. Not surprisingly , "Bombs Away" sounds quite a lot like Fleetwood Mac's "Rumours."

The good news is that, on the whole, it works. This is certainly the strongest Stewart album in a long time (the first in a long time, actually) and there are several possible single cuts that might spark Stewart's return to the musical forefront.

Stewart still has the lyrical touch, the occasionally brilliant way with simple words. One of the finest cuts here, "Lost Her in the Sun," is reminiscent of his classic "July, You're a Woman":

Given any day there's a jet flyin' somewhere,

Ah, she bought a ticket and she vanished in the sky.

How was I to know she was leavin' in the morning?

I never heard her go, she never said good-bye.

I learned to love the night 'cause the light's gonna get ya

Right between the eyes in the morning like a gun.

Reachin' out your hand and she's not there beside ya-

Oh, what can I say? Lost her in the sun . . .

Even the folkish phrases are effectively: "Is it wrong to be so in love with a girl / That you cant't tell her voice from the spinning of the world?"

Buckingham and Nicks have done well by Walter Egan - Perhaps they can do right by Stewart. CAPTION: Picture, EMMYLOU HARRIS: BACK TO COUNTRY WITH "BLUE KENTUCKY GIRL."