Marlene van Niekerk's debut novel, 1994's Triomf, was a portrait of a dirt-poor family living in a white township in the run-up to South Africa's first free elections. In their incestuous behaviour, van Niekerk presented an allegory for the conclusion of the apartheid project. She also showed us an often overlooked truth: apartheid was not only morally wrong, it was economically wrong-headed in that it failed the white working class, the largest constituency of those whose well-being it was designed to preserve.

Triomf was brutal and very funny. Conceptually bold, if not Ballardian, it was the work of a writer in complete control of her material. With her second novel, van Niekerk has produced, if anything, a more startlingly profound result.

The Way of the Women is a subversion of the homespun Afrikaner plaasroman or farm novel. It opens in 1996. Milla Van Redelinghuys, an Afrikaner farmer, is on her deathbed, looking back on her life. She is wasting away, the victim of a motor neurone disease. Milla's palliative care is provided by Agaat, a coloured woman who has been working for the family for 50 years.

Milla can communicate with Agaat only by blinking. Agaat reads to Milla from Milla's diaries. She also stimulates her captive audience with a number of nursery rhymes, folk songs and quotations from Afrikaner farming handbooks. Each of Agaat's interventions are charged with unspoken unfinished business from their shared history; each torment Milla as she slips in and out of consciousness.

"I know how Agaat's mind operates," says Milla. "She has no respect for a helpless human being. Possibly still pity. But not for long, then she wants to see signs of independence. She knows she'll have to generate it in me if she wants to see it, reaction, resistance. Because only when she's brought me to that will she have something to subjugate."

But Milla is an unreliable narrator. "Memories in me and I awash between heaven and earth. What is fixed and where? What real?" Delirium colours the recollections of the land she farmed, delusion the memories of her life-defining to-and-fro with Agaat. Does she want to confront the relationship between the past and present? Or is she happy in her delusions?

In its exploration of the complexities of truth, reconciliation and the dynamics of power in post-apartheid South Africa, this novel has been rather glibly compared to J M Coetzee's Disgrace. Van Niekerk has said that she envies Coetzee's "powers of understatement and relentless minimalist style". There is little evidence of that in this work. This is a long and funny book. It is also formally playful. The first-person narrative of Milla is interspersed with streams of consciousness and unpunctuated non-chronological diary entries.

For all of its narrative contortions, its allusive richness and the honesty of its truth-seeking, it will perhaps be seen as a landmark South African novel for a different reason, though.

In Disgrace, Coetzee writes of David Lurie, an English-speaking professor of communications, that "more and more he is convinced that English is an unfit medium for the truth of South Africa . . . Like a dinosaur expiring and settling in the mud, the language has stiffened."

The same has frequently been said of Afrikaans. But such fatalism is not for van Niekerk. The Way of the Women was written in Afrikaans. Some vocabulary remains untranslated and there is a glossary. Milla's farm is called Grootmoedersdrift, a name for which we are told there is no effective English equivalent.

In the prologue, Milla's son Jakkie - who lives in exile and works as an ethno-musicologist - muses on the character of the language: "Translations for wolfneusgewels, ruens, droeland, drif: jerkin-head gables, ridges, dry farming land, crossing. Prosaic. Devise something: wolf-nosed gables, humpbacked hills, dryland, drift. Always the laughter at the office, good-natured, collegial, at my attempts: grove of whispering poplars. I romanticise they say. Quite a fan of the homely hymn, that's true. Homesick for the melody and so on. But that's only the half of it. The rest is granular precision, unsingable intervals."

Later there is a reference to Afrikaans's place in the culture, a role more commonly identified by its association with apartheid. "There's more to language than is written in a dictionary," says Milla, when Agaat and Jakkie have an argument about a word in a game of Scrabble, ". . . and there would have been mighty little happening on Grootmoedersdrift if you'd had to farm only with the words in Chambers."

The Way of the Women is important, then, because even in translation it is a definitive affirmation of Afrikaans. A language that remains, inescapably, one of the mediums for the truth of South Africa. Tree of Smoke, Denis Johnson, Picador, 624pp, £16.99