On Fresh Horses (Capitol), Garth Brooks' first studio album in two years, the superstar veers between traditional country and '70s pop-rock like a sailor tossed from starboard to stern. Sometimes he even does it in the same song. He recasts Aerosmith's ''The Fever'' with the Western lyric of a rodeo rider. The song, an example of what Brooks calls ''garage country,'' is spurred to breakneck speed by hard-churning electric guitars and what sounds like a barn-dance fiddle on acid. It has every reason not to work, but somehow does. The same can be said for ''Ireland,'' a powerful, poetic song about an Irish soldier in battle, which might seem like a top-heavy anachronism but succeeds with its wonderful synthesis of shiny '90s production and ancient instrumental touches (a hurdy-gurdy).
Elsewhere, Brooks' writing is uneven, ranging from a ho-hum autobiographical road paean (''The Old Stuff'') to a confusing ghost story (''The Beaches of Cheyenne'') to a bordering-on-risque fairy tale (''It's Midnight Cinderella'') that adventurously pushes the envelope of country lyrics. (About Prince Charming he sings ''And by the way he's walkin'/I can guess where your slipper's at.'') This album is more good fun than great music, but even at its thinnest, Brooks' inventive risk-taking continues to set him apart from his paint-by-numbers competition. B-