The second solo recital in Dietrich Fischer-Dieskau's Carnegie Hall engagement found the baritone in tremendous form Thursday, careening through the colorfully populated landscapes of ''Des Knaben Wunderhorn'' with a zest and command that made for an unforgettable evening.

Who else has so roundly filled out Mahler's collection of soldiers and drummer boys, bumpkins and lovers, tale-tellers and satirists? No emotion, reaction, state of mind or point of view seems to lie outside Mr. Fischer-Dieskau's range. In the characterization of a song - precision of observation, fullness and detail of projection - he remains an unmatched virtuoso and a spontaneous communicator. Hartmut Holl, the young pianist who has been making a deep impression at these concerts, was with him every breath and mood of the way.

The recital began with gentle sentiment (''Rheinlegendchen'') and ended with a masterpiece of throwaway comic timing in ''Ich weiss nicht wie mir ist.'' Between came scorn, regret, deep gloom, irony and fearless assertion, all etched with the baritone's idiosyncratic but brilliant brand of vocal control. The encores brought their own rainbow of tenderness and rapture.

In all of this Mr. Fischer-Dieskau ''played the crowd'' in a way that assumed the best of it. He demands a lot of an audience, and rewards by raising its consciousness. You could feel attention and comprehension in the air; Mr. Fischer-Dieskau has lived long enough as a singer to inherit a part of his own legacy.

Will Crutchfield