Pictorially, "The Tree of Wooden Clogs," grand winner of last year's Cannes festival, is beautiful. Dramatically, it is laughable. Politically, it is ridiculous.

Ermanno Olmi's film, which is three hours long, is about peasant life in Lombardy at the end of the 19th century. It is shot in a palette of rust colors, in rough fields and rude dwellings. The sound is Bach organ music. The faces, those of Italian peasants who have not acted in films before, are strong and good; they are most expressive in trival moments of joking or quarreling, and rigid on occasions of joy or tragedy.

Almost any moment in the film could be stopped to make an effective and artistically composed still photograph. For a while, it is a deep pleasure to watch.

But even a filmgoer devoted to slow pacing grows impatient. "Days of Heaven," also a film wiht extraordinary rural beauty, had little dramatic structure, but it was shorter and more visually adventurous. The wheat and the sky were violently active, in a way that only an artistically used motion-picture camera could capture, providing more excitement than the complications of sex do in many films.

This film just keeps panning on and on, from one magnificently quiet picture to another, through three calendar seasons in the lives of five families of sharecroppers. A portrait of any one of them would enable one to imagine and appreciate the hard, predictable life they lead.

But the motion picture brings expectations of movement. An old man hopes to grow the first tomatoes of the season. Will he? A widow, her father and her six children scrape to make ends meet.Will they manage, or will the children be sent to an orphanage? The pig is butchered. Will there be bacon for breakfast? A shy man trails after an equally shy woman, finally marries her, then takes her on a honeymoon trip to Milan. Will they? Ever?

As it happens, the tomatoes grow as expected, and so does everything else.

One could classify this monotony as realism if it weren't for the naive and condescending way the peasant class is viewed. These peasants are all respectful of their betters, willing to sacrifice anything for education, chaste and devoted to one another and, above all, docile. They sing at their work, which they love. They stand at attention when the landlord plays opera records.

The terrible transgression that gives the film its title is that a father cuts down a tree to make a wooden clog for his small son so the boy can continue to walk six kilometers to school every day. When he is punished for this unauthorized act, the others stay in their houses to mutter and pray on his behalf.

And yet they are living in poverty in a time of political upheaval. Chained demonstrators are led past the honeymooners in a Milan street, and the peasant couple's only concern is to step back out of the way. These two are unusually passive - they accept the charge of a foundling on their first day marriage, without even talking it over, simply because her aunt the nun presses it on them - but no one in the film has energy except for work and family duty.

No doubt, that is what makes the idealized peasant so picturesque. It does not make them eloquent. CAPTION: Picture, THE PEASANT BOY IN "TREE OF THE WOODEN CLOGS."