I can think of a couple of good reasons to rake autumn leaves into huge piles. Neither involves stuffing them into plastic bags left at curbside until trash day.

Most important is Lynne’s need to jump head first from a running start into the pile, to hide perfectly still below the surface, breathing in the pungent organic odor, until rooted out by Reilly’s cold nose. I am too old to fly into the pile as Lynne does, but I have memory of being 10 years old on blue-sky October afternoons, my father heaping up the leaves after every flying leap. And I can still wrestle in the leaves with Reilly.

And I would pile them up to recycle their nutrients into leaf mold and compost for the garden. True, much of what leaves contain at the end of their life is reallocated to more permanent parts of the plant. But those dry, brown remnants of summer have a surprisingly high nutrient element analysis. Fallen leaves of deciduous trees such as maple, beech, ash and oak contain about 0.5 percent nitrogen, 0.1 percent phosphorus and 0.5 percent potassium, along with equally substantial amounts of calcium and magnesium, all essential nutrients for plant growth.

Because decomposition of leaves is a slow process, these nutrients are released gradually – nature’s version of a slow-release fertilizer. Indeed, annual topdressing with decomposing leaves, or leaf mold, is all the fertilizer that trees, shrubs and many perennials need for healthy growth. Even lawns are healthier for the nutrients released from fallen leaves by a mulching lawn mower.

Nutrients, however, are only part of the garden worth of autumn leaves. Leaf mold also improves both the structure and water holding capacity of the soil. While rich topsoil can hold 60 percent of its weight in water (compared to 20 percent for subsoil), leaf mold can retain 300 percent of its weight, or more.

The question then becomes not what to do with autumn leaves, but how to do it, how to make leaf mold? Start by shredding the leaves into small pieces that will break down quickly. This can be done with special grinders designed for the task or with a lawn mower. (I found one Internet source that actually recommended using a weed-eater to shred leaves in a trash can!) The resulting mulch can be immediately spread in the garden walkways to control weeds and around your trees and shrubs as well.

Some of the shredded leaves can be added to the compost pile, but only sparingly unless they are mixed with high-nitrogen materials such as grass clippings or stable manure. Too many leaves and the composting process stalls, while a mixture of five parts leaves to one part manure will decompose quickly.

Reluctant to rob nutrients from the woodland garden, we rely on a willing neighbor for an endless supply of autumn leaves. We wait for a blue-sky Saturday afternoon to walk down the road, rakes in hand, to make the piles. We build them tall and broad for Lynne and Reilly, and only when they have had enough do we haul the leaves home and make another pile beside the shredder.

Later, driving into town, we see piles of black plastic bags at the side of the road, bulging with leaves that will decompose long before the plastic rots, leaves that will never release their nutrients to nourish new life in a garden. We both say what we are thinking: that it is a crime.

Send queries to Gardening Questions, P.O. Box 418, Ellsworth 04605, or to reesermanley@shead.org. Include name, address and telephone number.