Even a garden path promotes composting

Last fall I piled leaves in the paths between the raised beds of my vegetable garden. By mid-July they had disappeared, decomposed into a thin, soillike layer of compost which could be readily scraped up and scattered between the growing plants.

That is one way of composting that gardener's bonanza - the annual leaf harvest which will start coming in any week now.

The plastic garbage bags filled with damp leaves and left in a far corner of the garden for the better part of two years, split open by themselves this summer to reveal almost no trace of the original leaves. In their place was a powdery substance that looked and felt like milled peat moss ready for use in the garden.

The nice thing about composting is that there are so many ways to do it. This means that there is likely to be a suitable composting option whatever your particular set of circumstances. If you know how to go about it, you can even compost indoors.

Composting is a very effective way of returning something very valuable to your garden soil at very little cost in either cash or effort. Anything organic, that is, anything that once grew, whether it is weeds, leaves, vegetable peelings, corrugated cardboard, etc., can be composted.

By adding these so-called ''wastes'' to his soil, the gardener feeds the microscopic soil life which, in turn, feeds the plants he or she grows.

A friend walked through my garden the other day when I was out.He left a note to say that something like 40 pounds of produce was waiting to be harvested.

He was exaggerating but not by much. The garden is highly productive and what made it that way is a ceasless composting program.

These, then, are some of my approaches to composting:

* Leaves in the path. I tried this on a large scale for the first time last year, and it worked so well that I shall continue the practice.

Leaves are spread in the paths between the garden beds. The paths are filled to the full 10-inch height of the beds. As they become compacted more leaves are added until there is a good thick layer there. During the following growing season the continual walking over the leaves grinds them down and this speeds up the decomposition. By July they can be scraped up and spread on the neighboring beds as a leaf-compost mulch.

Weeds and garden refuse can also be added to the paths. An additional benefit to this method is that it keeps the gardener's shoes relatively mud-free in early spring.

* The leaf pile. In one corner of my yard I pile leaves to about 4 feet deep, which compacts over winter to about half that thickness. From time to time, kitchen waste is taken out to this pile and buried in it, deep enough so that flies are not attracted. Any skunks or raccoons that visit the pile help aereate it as they dig for the food.

If manure is spread over the pile and then dug in, the decay process is hastened because of the nitrogen it supplies to the decay bacteria. Garden refuse could also be included.

In the spring I plant vining crops (squash, melons, or cucumbers) around the edge of this leaf pile and train the vines over it. After harvesting in the fall , much of the pile has been converted into a leaf mold which is then stored for use the following year or simply spread around the garden.

* Plastic bag or bin. Simply filling a plastic bag with damp leaves or garden refuse and leaving it untouched for about a year produces compost. If you wish to do this indoors, using kitchen scraps, I suggest a plastic bin with a clip-on lid.

Sprinkle each addition of scraps with peat moss or shredded paper. The idea is to absorb excess moisture so that the contents are about as damp as a squeezed-out sponge. When full, clamp on the lid and start a second bin. When the second bin is full you can usually begin using the first one.

Have tight-fitting lids for this type of composting as it takes place without oxygen and can give off unpleasant odors during decomposition. Once the composting process is complete there is no offensive odor and the compost can be used anywhere in the garden.

If the compost is not complete and still on the slimy, raw side, you can still use it. In this case dig a planting hole and bury it, leaving about 1 inch between the compost and the roots of the seedling being transplanted.

* Fast batch composting. Finally, I shred a mix of materials (leaves, weeds, kitchen refuse, and some manure if I have it) and place it in a compost bin. The mix is dampened and stirred every day. This daily introduction of oxygen to the pile speeds up decomposition so that considerable heat builds up in the pile.

After 14 days, when the temperature has returned to more normal levels, the compost is ready for use even though it is still far from totally decomposed.