With pop music virtually the major field for a financial bonanza in show business nowadays, it is only logical that the city of Nashville, Tenn., is hot television stuff.

Nashville, of course, is the general headquarters for that part of the pop music industry that specializes in the country sound. And since this particular sound has worked its way into much of the more sophisticated pop music in show business, the logic for the city's prominence in video is even clearer.

This past Saturday, the first regular, weekly, prime time network video series to originate in Nashville - the Johnny Cash Show - arrived on ABC-TV, an hour in length.

And this coming Sunday, another Nashville entry, and hour-long program entitled "Hee Haw," will arrive on CBS - TV.

The Johnny Cash Show replaced "The Hollywood Palace" for the summer, and "Hee Haw" is also a vacation - time series - taking over the slot vacated by the canceled Smothers Brothers program. Come fall, the Leslie Uggams series will occupy the time period, also a music - and - variety format.

From the very title, "Hee Haw," and from the look at upcoming performers on the series, it seems pretty certain that this show will stick, by and large, to the standard, traditional country-western musical approach. The co-hosts are Roy Clark and Buck Owens. And fans of the Smothers Brothers series may well swallow hard to think their being replaced by a show called "Hee Haw."

The Johnny Cash Show, on the other hand is a country oriented program with a quite obviously different style, and a different goal in mind. Its purpose, aside from entertaining, is to illustrate what might more properly be called country-folk music, the very music that has had such enormous impact on the more polished forms of the pop field. A look at last weekend's debut made that approach very clear.

Cash's program is, without doubt, the best country music show ever offered on network television. The only unfortunate part of the premiere was some gosh-awful comedy by a lady named Fannie Flagg, who would seem more likely to belong n a show called, say, "Hee Haw."

This mistake aside, however, the Cash show was very good. The production values were strong, and, above all, the star-singer-host immediately established himself as a man to be reckoned with on the home screen. He is the Frank Sinatra of the country-folk field. If his voice is not naturally as pure or as perfect in tone as some other singers, it matters little because he has what few performers in the singing field have. Character. It shows in his voice and manner.

He is a big, imposing man with a look of reality and hard earned experience about him. Country-folk fans know he is already a legend, and if you wonder why, you might pick up his "Folsom Prison" album. Taken in sum, he is therefore no surprise when the words of his songs ring true in the way of simple, earthy poetry. A young lady guest on the premiere, Joni Mitchell - excellent in her delivery, manner and voice - also sang with a highly poetical air. And I believe the words of their songs would make a worthwhile small book of poetry.

Bob Dylan showed up for the premiere also, taking a whirl in his own unique way at country music, but while it was of interest and sometimes effective, Mr. Cash dominated the night easily. He is some hombre.