In the late 1930s, having endured several brutal winters in a flimsy shack on the Texas Panhandle, Woody Guthrie invested five cents in a Department of Agriculture pamphlet called "The Use of Adobe or Sun-Dried Brick for Farm Building". The folksinger fell in love with the idea of constructing his own house from the earth on which it stood. He never fulfilled that dream, but he did turn it into a wad of fiction, undiscovered until recently and now published as House of Earth, the debut book from Infinitum Nihil, a fourth Estate imprint "helmed" by the actor Johnny Depp.

Guthrie characterised himself as a "hoping machine". When he dreamed, he dreamed hard, and so do his novel's heroes. Tike and Ella May Hamlin are subsistence farmers under siege from duststorms, drought and debt, keeping their spirits up with high hopes, roguish banter and lots of sex. In a typical episode, the Hamlins combine a discussion of adobe house-building with a bonk in the barn. "Ohh. Yes. That Department of Agriculture book was an awful mighty good thing, laying there at her elbow on that hay. But it made their misery even bigger, and their biggest dream even plainer, and their biggest craving ten times more to be craved. A fireproof, windproof, dirtproof, bugproof, thiefproof house of earth. His penis had become limber, and her moving had forced it out of her hole. He felt the liquids from her womb smeared through the hairs on his stomach …"

Such prose was clearly unpublishable in its time, and is still unusually explicit today. But it's all part of Guthrie's larger vision of human experience. Every sensation is noted and riffed on. Every thought is felt, every feeling anatomised at length. Weather permeates the soul and the soul mingles with the elements. The cry of Tike's newborn baby is described for two pages, because for Guthrie it is the cry of all things on earth, including the "noise of dry locusts on stems of bushes. High rattle of clouds of grasshoppers peeling off across the ranch … the jingle of rusty spurs hung on the windmill post … all of the hisses, barks, yelps, whoops, croaks, peeps, chirps, screams, whistles, moans, yells, and groans …"

Depp and co-editor Douglas Brinkley, in a somewhat distended foreword, do their utmost to convince us that this book is Guthrie's crowning achievement. Rather than focusing on its linguistic bravura, however, they contend that it's "a direct appeal for world governments to help the hardest-hit victims of natural disasters", as relevant to modern-day Haiti or Sudan as to 1930s Texas, ahead of its time not just in its sexual frankness but also in its ecological awareness. "It's almost as if Guthrie had written House of Earth prophetically with global warming in mind." By the 35th page of their intro, they've worked themselves up to a pitch of bombastic celebration.

But I can't help thinking that many readers will find House of Earth challenging in ways different from those trumpeted by Infinitum Nihil. At its best, the book is an eccentric hymn to the everythingness of everything, a sort of hillbilly Finnegans Wake. But very little happens in it, and there's not much social or political context either. If Guthrie aimed to give cosy, middle-class readers an insight into the grinding poverty of farm labourers, he chose a remarkably oblique angle. Every 20 pages or so, a vivid, documentary detail emerges – Tike papering the decrepit walls with flourpaste and old magazines, Ella walking in shoes soled from discarded truck tyres – but the overwhelming bulk of the prose is devoted to the couple's musings as they tease, cajole, josh and philosophise. There's an acre of soliloquy for every inch of action.

Guthrie was reportedly unimpressed with Steinbeck's attempts to render the dialect of farm labourers in The Grapes of Wrath, and was determined that Tike and Ella May should talk more authentically. Only a historian of linguistics can judge, but I imagine that speeches such as "I'll give you the smoothest an' th' nicest rubbin' job that any shemale ever got since Jesus quit paintin' little red wagons" may not be everyone's idea of sharecropper reality.

House of Earth is marketed as Guthrie's "only completed novel" (Bound for Glory and Seeds of Man were memoirs, albeit somewhat fictional) and the editors say it was "finished in 1947". But was it truly finished? One of the few elements of plot – a mysterious ailment of Ella's that's flagged up as portentously significant – is left unresolved. The fact that the Hamlins spend the entire book talking and dreaming without actually moving any closer to building their adobe refuge could be seen as a poignant sign of their powerlessness, but could just as easily mean that Woody intended to knock out another few hundred pages. A prodigious wordmonger, he produced stacks of articles, poetry and unpublished lyrics.

Depp and Brinkley admit that they made only the most minor changes to the novel's text, preferring to "let Woody's prose sing". More experienced editors would almost certainly have trimmed some verbiage from this 214-page cantata, arguing that two whole pages describing the differences between Tike's and Ella's laughs is one too many, that a sentence such as "A little sigh of tired sadness was in her voice" needs surgery, that "He made a snorting sound with his lips and teeth" could be cut to "He snorted", and so on.

But such concerns are probably irrelevant now. Had House of Earth been published in 1948, it would have been measured against the other new literature of that period, and against Guthrie's own Bound for Glory, issued five years before. Bound for Glory – which remains a potent, witty, highly readable book – was nursemaided by Guthrie's whip-smart wife Marjorie and then rigorously edited by EP Dutton's Joy Doerflinger. If House of Earth had been similarly tackled by Marjorie and Joy instead of kid-gloved by Douglas and Johnny, who knows what it might have been?

But, as Guthrie's disciple Bob Dylan once said, "let us not talk falsely now": nobody in 2013 is interested in House of Earth as a contender for literary prizes or as a rallying-call for protest. It's a historical curio, a precious relic of semi-legendary Americana. While it won't shame any bankers, it offers intimate, often startling access to the peculiar intellect and capacious soul of a 20th-century icon.

• Michel Faber's The Fire Gospel is published by Canongate.