Leaf Composting: Smart Organic Fertilizer

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Summary: Leaf composting, creates a valuable “crop” of organic fertilizer which should not be wasted. Mowing and mulching leaves into the lawn can help improve turf quality and vigor.

Question: During the fall we get piles of leaves. Is it best to rake leaves – which I hate and is time consuming – and create a compost pile, run the mower over them for leaf compost or let them lay where they are. John, Tuckahoe, Virginia

Answer: John, homeowners and lawn care professionals face the problem of what to do with fall leaves in the landscape. Handled correctly, this material – leaves – become a valuable byproduct with leaf composting and organic fertilizer.

Dropping Tree Leaves Packing Nutrients

As trees root more deeply than most plants, they bring up and store in their leaves minerals found deep in the sub-soil. Biological chemists preforming analysis of tree leaves to determine the mineral content and fertilizer value of different species.

These analysis show tree leaves contain:

  • Calcium
  • Magnesium
  • Potassium
  • Phosphorus
  • Nitrogen

The sugar maple ranks high, in quantity of leaf crop and fertilizer value.

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Leaves not only provide a source of minerals from deep in the soil but also a source of humus, the activator of the soil. Humus retains moisture, loosens and aerates the soil, improves drainage, feeds the bacteria which break down the soil wastes into plant foods and itself releases plant foods slowly.

We cannot continue to rob the soil bank without making some new deposits and not use its fertility.

Our biggest problem each fall is the proper disposal of the multitudes of leaves. Here we have two approaches, either pick up the leaves or dispose of them in place. Let us begin with the latter.

What can you Compost? Compost Leaves on the Ground!

Direct, on-the-ground leaf grinding is made possible by the use of many rotary lawn mowers equipped with suitable “mulching blades” and attachments. Their outstanding advantage is they reduce/cut leaves into a finer consistency. The leaves are drawn into the machine and cut to bits by the rapidly revolving blades.

This finely-shredded material falls to the ground as a beneficial leaf mulch, and free compost fertilizer, returning to the soil those nutrients which were taken from it. Likewise, the material is quickly incorporated into the soil, while it might take as much as two years for the whole leaves to decompose and the lawn grass beneath would be killed off in the process as well.

 

Raking Leaves – The Slow Alternative

The other alternative is to – rake leaves – which is slow. Ordinary garden rakes are too small and the teeth too short. They fill up quickly. Also, a lot of arm and leg work is required to clear a small space even when using a leaf tarp to gather the leaves. The modern rubber, plastic or wire rakes (yard brooms) are much faster than the old wooden rakes of yesteryear.

However, there are several rotary brush lawn and leaf sweepers available at a price moderate enough to justify their use on relatively small lawns and gardens. One with which I am familiar weighs but 15 pounds, has a canvas catcher which holds three bushels and operates at better than three times the speed of ordinary hand raking with little effort.

For large scale lawn sweeping and leaf gathering there are also machines that operates like a vacuum cleaner. For years municipalities used large suction leaf gatherers for collecting street-side leaves.

For homeowners, the use of a backpack leaf blower that is more flexible and less expensive and a whole lot more fun than hand raking or driving machinery around.

Once the leaves are raked or picked up mechanically, there is the problem of how to haul them away. One of the simplest ways is to rake or dump the leaves on a large canvas square (leaf tarps) or piece of plastic sheeting available from many of the larger garden centers. When it is full it is picked up by the handles or tied corners and carried or pulled away.

Grasscycling – The Value of Cut Grass

Of course, all we’ve said about the value of saving leaves also applies to grass clippings. A serious mistake is the discarding of these clippings, for this short-cut grass which British dairymen call “high-protein grass” is of great value as a soil improvement ingredient.

All to often these clippings are swept up and taken from the lawn where they were grown, dumped or sent off in a garbage truck. So it is that such organic materials, potentially rich in soil improvement value, are lost.

Now that we have the leaves and plant wastes collected, what do we do next? First, they can be applied as a fairly heavy mulch to such plants as camellias, rhododendrons, azaleas and other plants that require an acid soil, for without a little lime such materials are often acid. Such a use is good.

Secondly, we can mix the leaves and clippings into the soil, but unless incorporated thoroughly into the soil many leaves have a tendency to mat and remain undecayed for several years. That is not good.

Leaf Composting With Shredders or Grinders

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Thirdly, the material can be chopped up in one of the leaf shredders or grinders now readily available from manufacturers like Patriot, WorX, Flowtron, McCulloch, Troy-Bilt, Toro, Yard Machines, Ariens and restored to the soil as a mulch, incorporated into the soil or built into a compost pile.

Machines available for this purpose use to be too large and costly for homeowners and smaller commercial companies. Now, however, there are a number of them which serve the purpose well.

These are table or wheel-mounted machines, powered by electric motors, gas engines or belt driven by garden tractors. The price range of these electric leaf mulchers is within the budget of ordinary garden owners. An electric leaf shredder sells for around $150.

A larger capacity machine like a gas powered Patriot or Yard Machines model is priced somewhat higher ($500 – $900) but has a much higher per hour capacity. It all depends upon which best meets the particular need and pocketbook.

There are also some instances where bagged autumn leaves are a serviceable garden adjunct – a source of mulching material and composting for next year – but it is a time-wasting operation to try to hold bags open with one hand and stuff it with the other. The best way is to make a bag-holding frame to keep the bag open.

Bagged leaves, however, should not be stored in buildings. They are a fire risk and make a home for rats, mice and insects. Store them in a corner of the garden. The bags depending on the type may retain their tensile strength through one winter’s exposure.

Another good over-winter leaf storage container can be made of poultry wire. This should be about 4 feet high. A 1-inch mesh holds the leaves better than 2-inch. By such storage one can keep a supply of mulching material for keeping down the weeds and retaining moisture in the soil on next year’s vegetable crops and berry bushes.

Experience shows that many more gardeners need to know more about the advantages of mulching contrasted with weed pulling and ground cultivation, as well as the value of saving humus-building materials.