American Requiem, the opening track of Beyoncé’s eighth studio album, is many things. It offers a touch of state-of-the-nation address – “Can we stand for something? Now is the time to face the wind” – and a sprinkling of the kind of vague but apparently personal lyrics that send social media into a frenzy of decoding: what are her “father’s sins” that Beyoncé has apparently “cleansed” herself of? Who are the “fairweather friends” for whom she claims to be planning “a funeral”?

It’s also a loud statement of what you might call Beyoncé’s bona fides. She is, she avers, “the grandbaby of a moonshine man [from] Gadsden, Alabama” who furthermore has roots in Louisiana. “They used to say I spoke too country,” she protests, adding: “What could be more country than that?”

In a sense, this all feels quite surprising. For years, Beyoncé has been in an unassailable critical position: everything she’s released has been greeted with huge sales, ecstatic reviews and lengthy reflections on her peerless artistry, thus affording her the ability to do whatever she wants. Equally, you can see why she might want to shore up her position when launching a venture into country and western – which is very much what Cowboy Carter has been trailed as – and not merely because her performance with the Dixie Chicks (now the Chicks) at the 2016 Country Music Association awards, while garnering the usual critical acclaim, attracted adverse online comment from viewers, some of it flatly racist.

Country isn’t so much a genre as a law unto itself. It’s traditionally very wary of musical outsiders – be they the Byrds or Ray Charles – and presided over by a notoriously reactionary Nashville establishment. Moreover, it’s traditionally a musical voice of the rural poor and working class: you don’t want to be perceived as a superstar dilettante who’s decided to dabble just because you can.

Cowboy Carter duly presents itself as a major statement – 27 tracks and 80 minutes long – and arrives complete with co-signs from Nashville elders. There are spoken word interludes by Willie Nelson and Dolly Parton, the latter drawing comparison between perfidious old Jolene and Becky with the Good Hair, the love rival in Beyoncé’s celebrated 2016 track Sorry. The latter’s favour is repaid with a cover of Jolene itself, which Parton has been publicly petitioning Beyoncé to record for years, albeit with a new middle eight and coda alongside fresh lyrics that substitute swaggering menace and threats for the original’s desperate pleading – desperate pleading not really being on-brand where Beyoncé is concerned.

Elsewhere, the singer circumvents the issue of what you sing a country song about if you’re worth an estimated $800m (£634m) by indulging in murder ballad-esque storytelling on Daughter – which underlines the drama with a burst of 18th-century opera, and recasting her early years in Destiny’s Child in Nashville-friendly terms on 16 Carriages: “At 15 the innocence was gone astray / Had to leave my home at an early age,” she sings, making herself sound more like an outcast unmarried mother than someone who went on tour supporting Dru Hill and SWV.

You can say that amounts to laying it on a bit thick, but both Daughter and 16 Carriages are fantastic songs: acoustic guitars playing host to strong melodies and, on the latter, a vocal delivery that carries the distinctive patterns of rap. In fact, there are a lot of fantastic songs in the first part of Cowboy Carter, although its sheer length starts proving a problem. Her cover of the Beatles’ Blackbird is astute – Paul McCartney wrote it in tribute to the Little Rock Nine, a group of nine Black students who faced discrimination after enrolling in the all-white Little Rock high school in 1957 – if inessential, and there’s a distinct qualitative sag in the middle. It’s remedied by the simple expedient of going wildly off-piste: if the lambent soft-rock of Bodyguard gets you wondering whether the “departure into country” tag strictly fits Cowboy Carter, the sudden appearance of a straightforward hip-hop track, Spaghetti, confirms that it isn’t.

Thereafter the album goes nuts. Ya Ya offers a fantastic early psychedelic soul-influenced stomp that throws in a sample of Nancy Sinatra’s These Boots Are Made for Walking, an interpolation from the Beach Boys’ Good Vibrations and what sounds like a lyrical reference to Mickey and Sylvia’s 1958 hit Love Is Strange. Riverdance and II Hands II Heaven return to the house music influence of Beyoncé’s last album Renaissance. Oh Louisiana is 52 seconds of bluesy funk with a vocal sped up to helium pitch. It’s all incredibly well done and hugely entertaining, but the sense that the album is clinging on to its original concept by its fingernails – throwing in the odd lyric about rhinestones or whisky and the occasional intimation of pedal steel guitar – is hard to avoid.

You wonder if Cowboy Carter might have worked better split into two separate albums, with one concentrating purely on the country-influenced/acoustic material: there are moments when it starts to feel less like a coherent statement than one of those long 21st-century albums that offers listeners a selection box of tracks to pick and choose playlist additions from. Or perhaps its wild lurches into eclecticism are the point. Unwieldy as it is, it displays its author’s ability to bend musical styles to her will, be they country, hip-hop or the baroque post-psychedelic easy listening that seems to lurk beneath the vocal gymnastics of My Rose. If the results don’t quite hold together, Cowboy Carter still proves Beyoncé is impressively capable of doing whatever she wants.