First nonfiction book from Styron; This Quiet Dust, by William Styron. New York: Random House. 305 pp. $17.50.

Since his fiction began appearing more than 30 years ago, William Styron has enjoyed a critical and popular eminence not entirely free from notoriety. His first novel, ''Lie Down in Darkness'' (1951), was praised for its insight and psychological power, and criticized for its blatant similarities to Faulkner's masterpiece ''The Sound and the Fury.'' Later successes like ''The Confessions of Nat Turner'' and ''Sophie's Choice'' have drawn considerable unfavorable comment from critics who dislike Styron's heavily rhetorical prose style and sexual explicitness and who find his obsession with grand sonorous subjects geared toward best-sellerdom.

This first collection of his nonfiction writings will doubtless be welcomed as evidence by Styron's admirers and detractors alike. It's a miscellany of work written between 1953 and 1981, comprising book reviews, think pieces, tributes to his friends and colleagues, speeches given at schools he's attended, descriptions of his experiences as a writer, and accounts of the making of his several novels.

Proportions and emphases indicate certain preoccupations. Styron was often sought out to review books on assorted Southern subjects and personalities. He's especially persuasive on the celebrated diary published as ''Mary Chesnut's Civil War'' (''a great epic drama of our greatest national tragedy''). Another Styron specialty, which was evident in ''The Service,'' stimulated such interesting pieces as his laudatory reviews of Vietnam memoirs by Philip Caputo and Ronald Glasser, and his incisive analysis of the enigmatic personality of Douglas MacArthur (in a consideration of the general's ''Memoirs''). His backward looks at deceased friends include a moving account of William Faulkner's funeral and a really lovely ''Elegy for F. Scott Fitzgerald.'' Unfortunately, we're also treated to a bathetic, defensive eulogy on the late novelist James Jones (''the critics hauled out their greasy little toolkits, but they never get hold of you at all'').

Styron himself points out in a preliminary ''Note'' which is annoyingly condescending that ''readers who are familiar with my novels are likely to find here frequent echoes and reflections of my larger works.'' Indeed, the background and integrity of ''The Confessions Of Nat Turner'' (1967) are effectively articulated in the impressive title essay, which details ''my search for Nat Turner.'' His brooding consideration of ''slavery's continuation in the horror we have come to call Auschwitz'' clearly links up with Styron's Holocaust novel, ''Sophie's Choice'' (1979).

And, though it isn't spelled out, the concern with crime and punishment that infuses his very uneven 1960 novel, ''Set This House on Fire,'' shows forth powerfully in the present book's best section, ''Victims.'' Its centerpiece (''The Death-in-Life of Benjamin Reid'') is a thoughtful, candid account of Styron's aid in the efforts to rehabilitate a doomed young killer. It will inevitably be compared with the Jack Henry Abbott-Norman Mailer affair, and it should be said that Styron's chastened struggling with the issues of capital punishment, victims' rights, and ''the Christian doctrine of redemption'' seems far more admirable than Mailer's composed detachment.

Elsewhere among these essays, the Styron method is rather less appealing. He often overwrites, and overdirects the reader: The memoir ''Chicago: 1968'' lambastes Mayor Richard Daley as ''the hoodlum suzerain of the city. . . . this squalid person''; his review of ''Calley'' treats the disgraced lieutenant with simple supercilious contempt, focusing on his ''fathomless dereliction'' from duty. The point is unarguable, but it's buried under hysterical rhetoric.

So it is with virtually all of this writer's work. ''This Quiet Dust'' is minor Styron indeed, but it will be of real interest to anyone who has found his fiction rewarding.