Leaf Compost is a dark, friable, partially decomposed substance made by the microbial decomposition of fallen leaves. Similar to natural organic matter found in the soil, leaf compost serves as an organic fertilizer and soil conditioner, effectively increasing the organic content of soil. It improves soil quality, but is not, however, normally considered a fertilizer as it does not contain enough nutrients.
Why Compost Leaves at all?
When uncomposted leaves are added to the soil, microbes that help decompose them compete with growing plants for the nitrogen present in soil. This nitrogen shortage may cause a stunting of plant growth. However, using leaf compost eliminates this competition.
More importantly, leaves are a cheap source of minerals and nutrients that plants require. It is estimated that the leaves of one large shade tree can be worth as much as $50 of plant food and humus. Pound for pound, the leaves of most trees contain twice as many minerals as manure. For example, the mineral content of a sugar maple leaf is over five percent. Even common pine needles have 2.5 percent of their weight in calcium, magnesium, nitrogen and phosphorus, plus other trace elements.
Hence, composting leaves makes sense as it is a natural means of supplying soils the nutrients they need, and also ensuring that the fallen leaves do not interfere with plant growth.
Properties of Leaf Compost
Composting speeds natural decomposition (the process by which raw organic materials are converted into compost by micro-organisms) under semi-controlled conditions. As micro-organisms decompose organic matter, temperatures within the pile increase, sometimes approaching l50oF. at the center. These inside-pile temperatures speed the process, and kill many weed and disease organisms.
Ready to use compost is dark and crumbly in appearance. It is light to touch and has an earthy odor.
Benefits of Using Leaf Compost
Overall, leaf compost improves the physical, chemical, and biological properties of soil. The major horticultural use for leaf compost is to improve the organic content of soil. This results in the following benefits --
- Drought damage to plants is reduced as the compost increases the soil’s water-holding capacity.
- It supplies trace amounts of the 16 essential elements needed for plant growth.
- Adverse effects of excessive alkalinity, acidity, or over-fertilization are reduced by the addition of leaf compost.
- Adding compost enables soils to hold more plant nutrients for longer periods.
- Decomposition of organic matter produces organic acids which combine with iron and aluminum ions, thereby reducing their potential toxicity to plants. This also makes more phosphorus available for plants because free iron and aluminum can tie up the phosphates.
The added organic matter provides a food source for desirable soil micro-organisms.
Uses of Leaf Compost
As organic mulch on the surface of soil in place of peat moss, straw etc, leaf compost reduces rainfall runoff and maintains optimal soil temperatures.
Leaf compost may also be used in potting soil. However, no more than 25 to 30% of the potting soil should be leaf compost. Frequently leaf compost will continue to decompose and if more that 25 to 30% of the potting soil is leaf compost, there will be a significant volume reduction of the potting soil after one year.
How to Make Leaf Compost at Home
Leaf Compost can be made in the garden easily, but it takes at least five to nine months become it is ready to use. The basic procedure to make Leaf Compost is as follows --
- Shred or grind the leaves to ensure quicker and surer decomposition into compost.
- Mix four parts ground leaves with one part manure or other material liberally supplemented with nitrogen.
- Turn the heap every three days. Turning a heap made of shredded leaves is not difficult because the compost is light and fluffy.
There are several ways to speed up the composting process.
- Covering the compost heap with a plastic sheet, will keep the warmth in, and prevent it from getting too wet or too dry.
- Using earthworms (Vermiculture) to decompose the heap will ensure ready to use compost in merely six week’s time.
- Adding extra nitrogen (usually in the form of manure) to the leaf compost heap ensures it breaks down quickly. In case manure is unavailable, nitrogen supplements like cottonseed meal, bone meal and Agrinite will work almost as well.
Compost may also be made in Compost Bins, which are large boxes built to house compost. Based on principles of proper aeration and moisture retention, Compost Bins ease the decomposition of organic matter. With the proper combination of air and moisture, ideal conditions are produced for the activity of aerobic organisms responsible for the high temperatures that transform the organic materials into compost.
There are some factors that must be kept in mind when making leaf compost at home.
- First, the leaf pile should be at least 4 feet in diameter and 3 feet in height. Piles that are too small may not be able to maintain adequate temperatures for rapid decomposition. Piles that are too large, may not be able to achieve adequate, odour-free decomposition, espeically in the centre of the pile. The maximum size should be about 5 feet in height and l0 feet in diameter.
- Second, for proper decomposition, the pile must be kept moist but not soggy . Inadequate moisture reduces microbial activity, while excessive water may cause shortage of oxygen and anaerobic conditions.
- Third, weeds pulled out of flower beds or lawns should not be composted. This is necessary for reducing weed germination. Also, it is best to avoid composting diseased plants, or herbicide-treated lawn clippings until after at least three mowings.
Leaves may also be used to make Leaf Mould, the fine black powder that is similar to what is naturally found on the forest floor. Although it is not as rich a fertilizer, it is easier to make and is especially useful as mulch. To make Leaf Mould, enclose an open area with stone or brick fences, fill it with wet leaves. After a few months, these will break down naturally into Leaf Mould.