The next-to-last time I tried to carry out the ancient and honorable custom of burning autumn leaves the Arlington fire department arrived just as the pile was beginning to smell good and blasted the whole mess all over the lawn with their hoses while a man in a blue suit scolded me about some new damn law. The last time I tried it, in the back yard, a lady of fierce convictions came storming up and gave me a lecture the likes of which I had not heard since a kindergarten matron caught me in a closet offering a Hershey bar to a female classmate about whose anatomy I was curious.

The urban air, I finally came to understand, is now reserved for airplane noise and automobile exhaust fumes.

For a decade thereafter I dutifully raked my leaves to the curb, there to linger a long with those of the neighbors while the legendary county leaf truck did whatever it does instead of suck up leaves. Meanwhile the wind would redistribute them around the neighborhood, and since ours is a corner lot we always got back more than we had deposited. Between Christmas and Easter the leaves that had not been set afire by kids who like to see parked cars burn would drift into the storm sewers, clogging them in preparation for the spring rains.

Meanwhile I had become a subscriber to Organic Gardeining , a magazine whose horror of pesticides is exceeded only by its passion for compost. By turning my leaves and litter and garbage into compost, it said, I could conserve a vital natural resource and turn my tenth of an acre of sterile clay into a garden that would feed the family the year around, with some left over for Bangladesh.

Compost, compost, compost, saith editor Robert Rodale. Mulch, mulch, mulch. the problem becomes the solution. Trash and filth transmogrify into tilth, one's family draws closer, the children grow physically strong and morally straight through the wonders of natural food and natural nature.

Composting seemed the simplest thing in the world. Pile up the leaves and stuff and they quickly rot down into earthy richness, especially if you turn the pile now and then. Yes. Well. But a pile of leaves as big as a Trailways bus becomes a mere bucket of compost, and if it is salted with garbage it becomes a rat farm as well. Cut out the garbage and the leaves decompose so sedately they last well into the following fall.

The process can be speeded up. Compost bins are efficient, if you have the space. The only spaced in my yard is the garden. There also are wonderful, ugly machines that swiftly turn small amounts of litter into tiny amounts of compost at a cost of only a few dollars an ounce.

The problem is bulk. A pile of leaves is a pile of air with traces of organic matter, and each leaf guards its nutrients within cell membranes that resist the rotting process. Reducing the volume by compression cuts off the air the decay bacteria need. I was stymied until I learned last week that my mother has a wonderful machine that grinds masses of leaves and litter into shreds as fast as you feed them into the hopper.

I borrowed it, and the children were assembled with rakes to share the joys of the good and responsible organic life. The little boy jumped in a few piles a few times and disappeared. The big girls stayed, but there was no sign of the sense of reverence that suffuses the pictures of Rodale and his cohorts in Emmaus, Pennsylvania. All in good time, perhaps; at least they like feeding the ravenous hopper. I tried to discourage that, because early on the thing had eaten a bamboo rake I was using to prod a jam.

Half the leaves on the place had been reduced to flakes when suddenly the machine began to clank and clatter as though the Tin Man had fallen in. Metal fragments flew like shrapnel.

The plug was pulled and the beast whined and snuffled into silence. Keys, or pieces of keys, were scattered among the blades and along the ground.I felt in my pocket, knowing what would not be there.

Twenty-seven keys, to be exact, plus an ID tag and the U.S. Army P38 can-opener I had carried since basic training. Keys to the car, the house, the shop, the desk, the filing cabinets, a friend's house, to every lock that guards everything I hold dear. Fourteen of them were one of a kind. Some were minced, some battered to scrap, some still recognizable but unusable.

The sole survivor was a padlock key: the key to the padlock on the garage in which the machine is stored.

I do not know the moral of this story.