Husband your leaves for building soil

On any trash-collection day, September through November, suburban and city streets are lined with plastic bags jammed full of leaves. To most people, the falling foliage is nothing more than refuse to be bagged and thrown away.

What a pity! Smart gardeners prefer to gather all the leaves they can reach with their rakes.

No matter what their color, leaves are a gold mine of soil- building matter. One year's leaf litter from a single full- grown tree is worth at least $15 as fertilizer and humus.

Pound for pound the leaves from oaks, maples, elms, and other common trees contain twice as much calcium, phosphorus, and magnesium as manure.

And best of all, leaves are free for the raking.

Leaves are multipurpose, too. They make excellent winter protection for perennials, superior compost, and magnificent mulch.

Now is the time to gather this free fertilizer for next summer's garden. An afternoon spent collecting leaves will yield enough for most gardens.

Whether composted, molded, turned directly into the soil, or used as a mulch, leaves are most valuable for the fibrous organic matter they supply to the soil. Leaf humus will aerate heavy clay, improving the tilth and making the soil easier to work.

Sandy soils treated with leaves will soak up and hold rainwater for plant roots.

Sheet mulching is the easiest way of putting leaves to work in the garden. Rake the leaves directly into the garden and spread them about a foot thick. By next spring the layer will be well on its way to decomposition. The soil beneath this protective blanket will be moist and friable.

The leaves can be tilled or dug easily into the mellow soil.

Leaves also are perfect for storing root crops in the garden. Don't bother digging up those potatoes, carrots, turnips, and jerusalem artichokes. Simply mound some leaves -- two or three feet thick -- over the vegetables.

Mark the row ends with stakes tall enough to be visible through the snow. Then in midwinter, push aside the leaves and harvest these garden-fresh vegetables.

Perennial protection is another use for leaves. Tender roots and plant crowns can be tucked under a quilt of leaves for the winter. Shredded leaves are preferable for winter mulching, since they won't mat together like whole leaves. However, whole leaves can be used if they are mixed with a coarse material such as spoiled hay, wood chips, or corn cobs.

Leaves can be cut up with a rotary mower or compost shredder. A commercial shredder works best, but even running a lawn mower over dry leaves will tear the vegetation into small pieces to prevent matting.

Layer leaves about a foot deep over berries and rhubarb and around fruit trees and grape vines. In the spring the settled leaves will release valuable nutrients and break down into water-holding humus when worked into the soil.

Many gardeners store their leaves in plastic bags through the winter and then use the dry leaves as mulch between rows of vegetables the following summer. Leaves, especially whole ones, mat beautifully to choke out weeds and trap ground moisture while keeping the soil cool and loose for healthy root growth.

Don't forget pine needles. Coniferous trees shed in the fall and their droppings can be used much like leaves. Be careful, though, because pine needles are acidic, with a pH below neutral (7.0). Pine needles are best for acid-loving plants, such as blueberries, blackberries, potatoes, radishes, and raspberries.

Pine needles also provide perfect winter protection for strawberries. The needle mulch has a loose structure that traps heat, but allows the plants to breathe.

Leaf mold is easy to do, too. Simply rake together a pile of leaves and wait. In a year or two -- as little as six months if the leaves are first shredded -- the leaves will decompose into rich, dark humus, known as "black gold" to some gardeners.

To make leaf mold you should pack leaves in a bin or circular wire fence that rests on the ground. If you add limestone, wood ashes, or earthworms at different layers throughout the pile, you will accelerate the molding process. Water thoroughly. That's all there is to it.

When the pile has turned dark and individual leaves are no longer identifiable, the mold is ready to use, Leaf mold can serve as a potting medium, be worked into the soil, or spread on top as a mulch.

Composting is the key to quickly breaking down leaves into plant food. Why don't you build a compost pile this fall by layering five parts shredded leaves to one part manure or similar nitrogen-rich material.

Turn the pile after the first spring thaw. Continue to turn the pile at two-week intervals and the pile will heat up. Within two months the compost will be broken down and ready for use as a side dressing on early crops.

Whether you plan to compost, mold, or mulch, gather all the leaves you can this fall. Next summer this free fertilizer will help you grow more food for the table.

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