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Many people think that composting is both difficult and unnecessary. After all, compost and fertilizers are available “right out of the bag!” But avid believers in composting know better. They recognize and are sensitive to the gifts that nature provides to the gardener and are acutely aware of the benefits to be derived from home composting.

Benefits of Composting

The main justifications for creating your own compost heap include
• cost savings derived from having a ready supply of organic matter to work into your soil – it allows sandy soils to retain more moisture and clay soils to drain better
• enhanced flavour and nutritional value of home-grown, composted fruit and vegetables
• assurance of the absence of chemical additives
• satisfaction in the knowledge that your organic waste is being put to good use rather than ending up in municipal landfill

Principles of Composting

When creating a compost pile, the objective is to achieve the best possible conditions for the proliferation of hard-working microorganisms essential to the process of decomposition. Fungi, bacteria and other microorganisms together with earthworms and various insects combine their efforts to decompose and digest organic matter. The fruits of their labour result in the wonderful, rich and crumbly material we call compost.

Creating Ideal Conditions

The efficiency of the process of composting depends on activators. These get the pile working and speed up the composting process. Good activators include manure, bonemeal and rich compost from a finished pile – trade a bucket or two with your neighbour! Other good activators are Comfrey, Tansy and Yarrow.

Yeast also mobilizes bacteria to multiply resulting in increased activity in the heap and an accelerated rotting process. The recipe for one cubic metre of compost is:
1 cube (25g) fresh yeast (not dried), 1 kg sugar and 2 litres warm water. Prepare as for dough – break yeast into small pieces and sprinkle with 2 tbs sugar. Blend well. Pour the remaining sugar into a 10 litre container and cover with 2 litres warm water. Stir until the sugar is dissolved. Then add yeast and stir well. Immediately water the solution on to the compost heap.

The speed of decomposition will also depend on particle size. In the absence of a shredder, reduce the size of leaves and twigs by running the lawn mower over them before adding to the compost heap.

Other factors essential to the composting process include moisture, aeration and achieving a balanced ratio of carbon to nitrogen.

Compost Content

Anything of living origin can be composted. That said, the quality and quantity of materials used will affect the composting process and will determine the nutrient value of the finished compost.

Compost organisms require the correct proportions of carbon, for energy, and nitrogen, for protein, to function properly. This is referred to as the C/N ratio. If the ratio is too high (excess carbon), decomposition slows down and nitrogen is depleted. On the other hand, a low C/N ratio (excess nitrogen) results in nitrogen escaping into the air, causing unpleasant odours, and into water, creating pollution.

A balanced ratio is achieved by alternating layers of high carbon materials, such as sawdust, and high nitrogen materials, such as fresh grass clippings. In general, brown or yellow, dry and bulky materials tend to be high in carbon and green, moist and fairly sloppy materials, high in nitrogen.

Most organic materials supply a wide range of nutrients needed by compost organisms and plants. Remember that the greater the variety of materials you introduce into your compost, the greater the certainty of creating a nutritionally balanced product.

There are some organic materials to avoid when composting. These include
• human and pet faeces that may carry disease organisms
• meat scraps, bones and fatty materials that decompose slowly and may attract animals
• waste matter that may be contaminated with heavy metals, pesticide residues or other toxic substances

Essential Elements

All living organisms need water and water is essential to the composting process. Good compost should be kept moist but not wet as beneficial organisms cannot survive in soggy conditions.

Check the moisture level every few days and, if necessary, add water when you turn your compost. Layer wet sloppy materials (fruit wastes, etc.) with absorbent materials, such as sawdust or shredded dry leaves, and turn the pile to release excess moisture that impedes proper heating.

Mindful that excessive moisture drives out air, drowns the pile and washes away nutrients, compost should be protected against the weather. Process compost in a covered bin or place a layer of straw or a tarpaulin over the pile. Shape the compost heap to work with the weather conditions. In humid climates a pile with a rounded or convex top repels water whereas, in dry climates, a sunken or concave top enables the pile to collect available moisture.

Another key element to successful composting is air. All living organisms need air to survive. The supply of sufficient air to all parts of a compost pile aids the process of decomposition. Frequent turning of the pile is the most straightforward method to ensure airing. Other aeration tips and techniques would include
• shredding leaves, hay and garden debris before placing on the compost heap
• inserting sticks into the pile when building it and then pulling them out later to open air passages
• poking holes in the compost with a garden fork
• burying perforated drainpipe at intervals in a passive compost pile
• sunflower stalks and straw also conduct air into the pile
• limiting the height of the pile to 1,5 metres to avoid compression
• using paper and grass clippings sparingly as they tend to form impermeable mats when wet

Getting Started

Start with a site that is well drained and spread a layer of sand or gravel to avoid water accumulation. Alternatively, use a base of coarse material such as brush or wood chips to ensure good drainage and allow air to penetrate from below. Thereafter layer with shredded leaves, hay, garden debris and kitchen waste such as fruit peels, lettuce leaves, egg shells, coffee grounds and tea leaves. Shredded paper and grass clippings may also be added to the pile but should be used sparingly to avoid forming an impermeable mat when wet.

Alternate layers of organic matter with layers of soil, manure or finished compost until the pile reaches a height of about one metre. A heap that is one metre square will generate enough heat during decomposition to sterilize the compost. To speed up the process, the compost pile would benefit from an activator.

The structure used for composting is not important. There are various types of compost bins available at local nurseries. These are convenient and make turning the compost easier, but they are not necessary. Compost bins or enclosures made of wood (non treated), plastic, bricks, wire, stones or any other durable weatherproof material would do the job just as well.

Once the heap has been turned and cooked twice, it is left to mature for about six months. At that stage it would be in the best condition for use. If left longer the worms will continue to work it over, increasing the richness, but ultimately decreasing the quantity.