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Making organic compost

Making compost presents the gardener with an economic and easy way to recycle disease-free garden, kitchen and general waste. Nowadays there are many ways in which organic compost can be made. Commercially available you get compost equipment like compost drums, compost turners, compost aerators, compost makers, compost containers, compost barrels, and compost tumblers. However, since we are making the assumption that we are gardening on a shoestring budget our compost recipe for making compost will not require these, sometimes expensive, compost equipment. Instead our organic compost recipe willshow you how to make compost using a compost heap. Organic compost can be made in many ways and this compost recipe will be a guideline only.

The ingredients for making compost

The most suitable materials for composting are all organic materials that will rot or decay easily. These materials will include:

  • Garden waste: non-woody garden prunings, grass cuttings, leaves, flowers, and vegetable remains.
  • Kitchen waste: vegetable peels and leaves, fruit peels and cores, nutshells, cooked table scraps, tea leaves, egg shells, even stale bread.
  • General waste: torn-up newspaper and cardboard boxes, sawdust and wood-shavings, animal manure, wood-fire ash, and kelp or seaweed.

Unsuitable materials, albeit organic, for the compost heap will be materials such as garden waste that has been treated with pesticides, kikuyu grass, woody garden clippings, pine needles, rose cuttings and other cuttings with thorns, bulbs, seeds, runners, toilet waste or septic tank sludge, diseased animal carcasses and diseased plants, as well as materials such as metals, glass and plastic as they do not decompose easily. (Tip: Avoid using the same type of organic matter, for example just grass clippings from the lawn or leaves alone because it has a tendency to form a mat with poor aeration.)

Building the compost heap

  • Depending on the amount of compost that you want to make, we recommend digging a trench into the ground approximately 2 meters by 2 meters.
  • Mix the organic materials well and chop up any big pieces.
  • Put down about 10 cm of mixed organic material. Start with carbon materials such as wood-shavings and twigs, follow this by a layer of nitrogenous material like grass clippings and leaves.
  • Add a compost activator to speed up the decomposition process. Commercial compost activators are available at garden centers and reputable nurseries. Alternatively you may use a bucketful of mature compost, animal manure, or bone meal as these work the same as compost activators. (Compost activators are micro-organisms that break down the organic matter.)
  • You can also add garden soil to the growing heap. Garden soil contains many organisms that will multiply and help the rotting process. Garden soil also contains useful nematodes such as earthworms. Earthworms are valuable members of the compost heap community. They eat plant material and produce worm castes that are very rich in nutrients. They also help to mix the compost ingredients and put air into the heap thereby speeding up the process of decay.
  • Repeat the layering of the compost heap in 10 cm increments. (Tip: The last layer should be garden soil, dry grass, leaves, or sawdust, as this will keep smells in and not attract flies.)

Turning the compost heap

When approximately one week has passed, push your hand into the compost heap and you will feel the heat generated by the decomposition process. After a few weeks the compost heap will have cooled down. This cooled down compost heap means that you need to turn the compost heap so as to allow it to heat up again. The heat will kill weed seeds and fly larvae. (Tip: Make use of a compost thermometer. These are available from garden centers and nurseries.)

To speed up the compost formation in the compost heap it should be turned. Turning encourages decomposition. The time between 'turnings' of the heap depends on the speed at which decomposition takes place, and this in turn depends on the ingredients in the heap, and the weather. The correct temperature range is necessary for composting. The rate of decomposition is much faster during the hot and humid summer months.

Watering the compost heap

Organisms require oxygen and moisture to decompose organic matter. So keep the heap moist, but not water-logged as this inhibits decomposition and will make the compost smell. If it does get too wet, add absorbent material such as sawdust, straw, or manure, and turn the heap. A badly aerated compost heap has an unpleasant smell and it is thus necessary to turn the heap over every two to three weeks to help with aeration. (Tip: The compost heap should be damp, not soggy.)

Controlling pests on the compost heap

A correctly cared for compost heap should not create fly, rat or mouse problems in the garden. Flies can be controlled in a compost heap by immediately covering new material with dry soil, sawdust, grass or leaves. Since flies breed in compost, it is necessary to turn the compost heap frequently so that enough heat is generated to destroy fly eggs and pupae. If you do find large white worms in the compost, destroy them. They are the larvae of the large black and yellow fruit beetle which does much damage in the garden.

Do not add meat scraps to the compost as this will attract rats and mice.

Do not use any poisons such as insecticides to control pests as these will stop the decomposition process by killing the organisms responsible for decomposition, e.g. fungi, earthworms, bacteria.

Troubleshooting the compost heap

Making compost is really quite easy, but having too much of a certain material or letting the compost get too wet or too dry can cause problems.

The compost heap is damp and warm in the middle only

This could be the case if the compost heap is too small, or the weather might be too cold and composting is this slowed down. Ensure that your compost heap is at least 1 meter high and 1 meter wide (1 meter equals approximately 3 feet.) The compost heap may be smaller if you make use of a compost bin.

The compost heap is stagnant; it does not heat up at all

There are several reasons why the compost heap can appear stagnant. Insufficient nitrogen, insufficient oxygen, insufficient moisture, cold weather, or simply the compost is finished. In the case of insufficient nitrogen you should make sure that you have enough nitrogen rich sources like manure, grass clippings or food scraps. In case of insufficient oxygen you should mix up the compost heap so as to allow it to breathe. In the case of insufficient moisture you should mix up the compost heap and water it to introduce some moisture into the compost heap as a dry heap will not compost. In the case of cold weather it is advisable to wait for spring, cover the heap or make use of a compost bin.

The matted leaves and grass clippings do not decompose

The main reason would be that there is poor aeration of lack of moisture in the compost heap. Address the situation by avoiding thick layers of just one type of material. Break up the layers and mix up the compost heap so that the materials mix. Do shred the big materials that are not breaking down well.

The compost heap stinks like vinegar or rotten egg

The main reason for a stinking compost heap could be that there is insufficient oxygen or the compost heap is too wet or compacted. Aerate the compost heap by mixing it up to enable the compost heap to breathe. If the problem is caused by too much moisture then add dry materials such as straw, hay or leaves to soak up all the excess moisture. If the smell is too bad then add dry materials on top of the compost heap and wait till it dries out before attempting to mix up the compost heap.

The compost heap smells like ammonia

The ammonia smell is caused by insufficient carbon. Remedy the situation by adding brown materials such as leaves, straw, hay, shredded or torn-up newspaper, etc.

The compost heap is attracting rats, mice, flies, etc

These animals can be attracted by the addition of inappropriate materials to the compost heap. These materials include items like meat, oil, and bones. Else it can be a situation where the food-like materials are too close to the surface of the compost heap. You should bury kitchen scraps near the center of the compost heap. You also should not add inappropriate materials to the compost heap. Alternatively you can make use of a rodent-proof closed compost bin.

There are fire ants in the compost heap

Fire ants can make their appearance if the compost heap is too dry, or not hot enough, or the kitchen scraps are too close to the surface of the compost heap. You should make sure that the compost heap has a good mixture that will heat up and you should keep the compost heap moist.

The compost heap attracts insects, millipedes, slugs, etc

This is a normal situation and part of the natural process of composting. This is not problematic.

How to compost your garden

Compost is mature and ready to use when it looks crumbly and has an earthy smell. It can then be dug into the top-soil of garden beds or spread as a mulch under trees and bushes. Compost also makes a very good potting soil mixture for houseplants or seedling trays. (Tip: Under ideal conditions your compost should be ready after six weeks.) The following are the recommended ways in which to use organic compost.

  • For bed preparation: – the most beneficial way of adding organic compost to the garden is to add it into the flower bed prior to planting. You should dig over the garden soil. (Tip: Dig the soil to a depth of about 60 cm, or two spade depths.) Remove root and rubble. Work the compost into the soil at a ratio of 1 to 2 parts compost to 3 parts of garden soil. (In other words 30-50% compost per soil area.) Add super-phosphate, hoof- and horn meal or bone meal at the same time so as to stimulate root growth. If you prepare whole beds, the new plants will establish much quicker and evenly.
  • For individual planting: – you will require a well-prepared hole if you wish to plant in established beds, or in areas where there is already lawn or paving. Make the whole as large as possible and place the soil to one side. Add 1 part compost and 2 parts of the soil, and the required fertilizer (depending on the plants) and mix. Use this mixture to fill the hole and spread the rest of the mixture around your new plant. (Tip: Do not place a layer of compost at the bottom of the hole as it may cause root burn.
  • For potting and bagging purposes: – making your own potting soil is easy. All that is required is adding a measly 30% compost to soil. Too much compost will be too rich and might cause root burn or hold too much water.
  • For soil enhancement purposes after planting: – soil amendments have to be made on a regular basis to keep plants healthy. Soil amendment is best made by placing a layer of compost approximately 10 cm thick over the flower bed and working it into the soil with a garden fork. Many people opt to use their mulch from the last season in this fashion and then add a new layer for the new season.