How to make your own compost with Elmarie Stoltz
Organic fertiliser or compost is highly rated as the fertilizer of the future. Compost forms continually in nature as plants decompose and animals die. Decomposition is the process in which organic material (plant and animal remains) is broken down into simpler components, by bacteria and micro-organisms. As a result of decomposition into compost, an earthy, dark, crumbly substance is formed. This organic substance is called humus and contains nutrients necessary for plant growth.
Compost or humus acts like a sponge, thus helping the soil to retain moisture and plant nutrients. The crumbly structure thereof helps to break down heavy clay soils and binding sandy soils to a loamier soil. Quick run-off of water and erosion is reduced by humus, and soil drainage is improved drastically. Because of the nutritious nature of compost, the need for chemical fertilizers is greatly reduced, if not eliminated.
This is an excellent opportunity for any gardener or small-scale farmer to produce their own nutrient-rich compost for their crops or gardens by using easily accessible materials like grass clippings, animal manure, leaves or any available substance that is suitable for composting.
How to make your own compost
Composting is a matter of providing the ideal environmental conditions for micro-biological life. This can be obtained by providing the following factors:
Composting is done by aerobic micro-organisms – the composting heap must, therefore, be sufficiently aerated. If not, slow decomposition will occur. Anaerobic microbes will take over if the compost heap is not well aerated and this will lead to bad odours given off by the heap. Green grass clippings and wet leaves are examples of composting materials that mats down easily and should be thoroughly mixed with materials like sawdust and straw for better functioning of the compost heap. The heap should also be turned with a spade or garden fork to give it a more “fluffed-up” condition for better aeration.
The compost heap must be moist, but not waterlogged, almost like a wrung-out sponge. If the heap is too wet, it will inhibit decomposition and will release bad odours. At the ideal moisture content, there is a thin film of water around each particle in the heap, that improves the distribution and activity of microbes. If the pile is too dry, it will slow down composting significantly. In dry conditions it may be necessary to wet the compost heap from time to time and in wet conditions, to provide cover over the heap to prevent too much water from penetrating.
Heat in the compost heap is a sign that the micro-organisms are at work. If the moisture content and oxygen in the heap are sufficient, the temperature may well exceed 55°C, which is a desirable temperature because all weed seeds and fly larvae are killed. More microbes are then also present, therefore the warmer the heap, the quicker the decomposition. It is helpful to insulate the heap to contain the heat inside the heap
The nitrogen/carbon ratio in a compost heap is of the utmost importance. Nitrogen can be obtained from “greens”, such as materials like fresh grass clippings, fruit and vegetable scraps, green leaves, coffee grounds, tea leaves and fresh manure. Carbon can be obtained from “browns” such as straw, sawdust, autumn leaves, corn stalks, etc.
“Browns” are made up of long chains of sugar joined together and serves as energy for the microbes. “Greens” or nitrogen, on the other hand, is a critical element in amino acids and proteins and is a protein source for microbes to multiply.
What is compost?
It is preferred to leave grass clippings out in the sun to dry first before using it in compost because the clippings form a mat that doesn’t aerate. If green grass clippings are used, it should be in limited quantities and it should be mixed with some brown material first.
Hay is an excellent material to use in composting. The greener the hay, the richer it is in nitrogen. Hay should be well moistened before adding it to the compost heap.
It is important to know that leaves are one of the best and compostable materials to use. Leaves will lose over 75% of their volume when composted, so what seems like a big pile, in the beginning, will actually be much less in the end. Care must be taken because leaves may cause matting down. To prevent matting, leaves can be shredded with a lawnmower before putting them into the heap.
Some kitchen wastes such as fruit and vegetable peels, tea bags, coffee grounds and eggshells are very good composting materials. Avoid composting meat scraps and milk products as they attract pests that may cause problems in the home and in the field. As kitchen waste contains enough moisture, it is recommended that you mix it with dryer materials such as sawdust and hay.
If composted, horse, cattle, sheep and poultry manure can be very useful to the plants. It is not advisable to apply fresh manure to plants, as it can burn the plants and the potential nitrogen in the manure is not yet available for the plants. Manure will accelerate composting because it heats up the compost heap.
Straw is a good aerator of a compost heap and helps “greens” to decompose quickly. The straw that has been used as bedding material in stables breaks down even faster, because of its combined structure with manure.
Wood chips and sawdust
Wood chips should be as small as possible, otherwise, it may take too long to decompose. Be careful with chemically treated wood, because it could be adding toxic substances such as arsenic to the compost heap.
How to make your own compost heap
Choosing a location
It is important that you have easy access to the compost heap and that the materials used for composting are close by. There should be a good balance between sun and shade on the heap so that it doesn’t get too dry or remain too wet. The heap should be built on a surface with sufficient drainage and close to a location that can use the nutrients that leaks from the compost heap.
Water should also be close by so that you can wet the compost heap when needed. Stay away from pine trees, because the needles that will drop onto the heap are low in carbon and will slow down the composting process.
Building the heap
Wet the ground underneath the heap. If you wet the ground underneath the pile, it will prevent the soil from absorbing the moisture out of the heap. It will also encourage earthworms to penetrate the heap and help the decomposing process.
A layer of twigs and coarse materials
At the bottom, place a layer of twigs and coarse materials approximately 5 to 10 cm thick. This will allow air circulation at the base of the heap that ensures better aeration in the heap.
“Brown” and “green” layers
It is difficult to mix the carbon and nitrogen or brown and green materials to the correct estimated ratio, so put them in layers on top of each other instead. Layers should be 10 to 15 cm thick, but limit grass clippings to prevent matting. Wet each finished layer of the heap. It is important that 45 – 50% of the weight of the compost heap should consist of water. Try to maintain a 50/50 ratio between “greens” and “browns” for the correct balance of nutrients. When the heap is turned for the first time, the “browns” and “greens” will mix with each other. Chop or shred the materials as much as possible so that it can decompose easier.
It is normally a good idea to add a thin layer, about 2cm of garden soil as a top layer. This introduces microbes to the heap so that decomposition can start as soon as possible.
Cover the heap
It is a good policy to cover the heap to keep in moisture and to keep out the rain. A black plastic bag is ideal. This step is optional and own discretion may be used.
Monitoring the compost heap
- The compost heap should be heating up in a few hours’ time. The temperature can be tested by sticking your arm into the heap. Be careful as it could burn you if the heap is working effectively. If the heap doesn’t heat up, you most probably don’t have enough nitrogen or “greens” in the compost heap.
- The moisture content must be maintained at 45 – 50%. The compost should feel like a wrung-out sponge and should contain enough water to almost drip when you squeeze a
- Composting time will be decreased considerably when you turn the compost pile regularly. By turning the compost heap, aeration increases and all the material gets exposed to the hot centre. The heap should be turned when the temperature inside starts to decrease. The heap should be wetted every time you turn If you turn the heap correctly, the inside should be out and the outside should be in. The season has little effect on the compost heap because it is the heaps’ centre temperature that is the crucial factor.
When is the compost ready?
The compost is ready for use as soon as the compost heap fails to heat up once more after being turned. The original ingredients of the compost heap should be hard to recognise at all, except for materials like a straw that will not be fully decomposed. Finished compost has a dark colour with a “soily” structure and the smell of humus on a forest floor. The volume of the finished compost heap will be 25 – 40% of the original compost heap. The time taken for compost to be ready depends on how often you turned the heap, if sufficient wetting occurred and if the right materials were used to build the heap.
WHAT NOT TO COMPOST:
- Chemically-treated wooden products
- Diseased plants
- Human waste
- Meat, bones and fatty food waste
- Pernicious weeds
- Pet waste
Composting methods and structures
Wire mesh compost bins
These compost containers are multipurpose, cheap and easy to build. Compost can be made in these containers with very little effort. As the organic material becomes available, it is simply placed in the container until the container is full. Except for wetting the compost regularly, no more effort is required. The compost will be ready for use within 6 months to 2 years time.
If the compost needs to be ready sooner, it will have to be given more attention. The composting process can be speeded up by the following practices:
1 Shred the organic material into smaller pieces.
2 Wet the compost regularly and keep the moisture content constant by covering the structure with plastic.
3 Turn over the contents of the structure regularly.
To turn over the compost quickly and easily the following steps can be followed:
1 Untie the wire mesh framework at the joints (See Fig. 1 and Fig. 2).
2 Remove the framework.
3 Re-erect the structure right next to the compost heap.
4 Place the material back into the structure from the top. The bottom layer of the heap will probably be composted already and may, therefore, be used in the garden.
Seen from the top the structure may be round or pentagonal, but because the round structure is much cheaper and easier to erect, this method is recommended. The wire mesh to be used may be an ordinary chicken wire or wire mesh The ordinary chicken wire is much cheaper, but loses its shape and must be supported very sturdily on the sides. It can also be used only a few times and must then be replaced.
The measurements of the two structures are as follows:
Circular structure (Fig.1)
Diameter: 1,07 m
Circumference: 3,81 m wire mesh with a height of 0,9 m and mesh size of 25 mm or 12,5 mm
When using chicken wire, wooden pegs or steel poles must be driven evenly into the ground around the structure for support.
Pentagonal structure (Fig.2)
Five panels of 0,9 m long and 0,6 m high of wire mesh with a mesh size of 12,5 mm are required.
How to make your own round compost structure
Cut a 3,8 m length of wire from the roll. Fold the last 75 – 100 mm at each end in order to form sturdy ends for the joint. Now join the two ends firmly with binding wire. Place the circle in a suitable spot for the making of compost. Drive 4 or 5 wooden pegs, evenly spread around the circumference of the circle, into the ground, making sure that the pegs are standing firmly, but still reach the top of the structure.
Cut the same length of wire as with the chicken wire, but cut the loose standing end of the wire with a pair of pliers to prevent injuries to persons. For additional safety, the ends are filed down smoothly. Bend the wire to form a circle and join with binding wire. This structure will be firm enough to stand on its own and pegs are therefore not necessary.
Pentagonal (five-sided) structure
Cut 5 lengths of wire measuring 0,9 m from the roll of wire mesh, with a width of 0,6 m from the roll, ensuring that the wire is cut in the middle of an eyelet in the mesh, leaving pieces of wire protruding at each side. The lengths of wire are then placed so that the loose wire ends tuck into the ground. The five panels are then joined with binding wire and the wire ends protruding at the top are bent with a pair of pliers or a hammer, to prevent the person placing material into the structure from being injured. The wire ends at the bottom ensures that the structure stands firmly.
Concrete block composter (Fig. 3)
Concrete blocks or bricks may be used for building a composting structure. It is easy to build and the turning of the organic material can be made easier by building two of these structures next to each other. The material on the top of the one structure can then be scooped off and placed in the bottom of the other structure. With this method, the organic material can be transferred layer for effective composting.
Erection of structure:
Materials required: 48 concrete blocks Procedure
During the building of the structure one of the following
procedures may be followed:
1. The concrete blocks can be stacked so that the holes in the blocks are at the sides.
2. Alternatively, the blocks may be stacked with the holes in a vertical position. Care must be taken to ensure that the openings between the blocks are large enough to provide the organic material with sufficient oxygen for aerobic digestion. The openings should however not be too large, as this may cause the organic material to fall through the openings.
How to make your own compost in a metal drum
By using a 210 l drum and drilling it full of holes, a very handy composting unit can be made. The holes are made to aerate the compost. The organic material is then simply placed in the drum in layers for composting.
When the compost has to be turned, it can be thrown out, turned with a garden fork and replaced. If more than one drum is available, a two to three drum system can easily be implemented. Holes must also be drilled into the bottom of the drum for drainage of excess water and to reduce the risk of the drum rusting. It is also convenient because it gives the micro-organisms in the ground access to the compost.
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