Plants need nutrients, and the easiest way to feed them is with compost
The importance of composting
Any successful home food gardener knows how important it is to feed the soil regularly with goodquality compost for the best crops. This is particularly so in South Africa as our soils are generally poor. The benefits of good compost don’t end with providing nutrients – compost also improves drainage and keeps soil moist for longer.
A compost heap can be made within a variety of containers, from a constructed wooden box to a chicken wire bin. Containers keep the compost neater, but a heap placed directly on the soil is just as good. A box constructed of timber should have air holes between the timber slats to ensure aeration and should not be higher than 1.5 metres. Two or three boxes used in succession are ideal – as one matures the other is filled. Place bricks or clay pipes in the bottom of the box, about 10cm apart and covered with woody plant stems or small twigs, to help with air circulation. Place the boxes on soil and not concrete, as the soil base helps with aeration and drainage.
How much space do you have?
Generally speaking, the bigger your garden the more space you will have (and need) for your compost area. There are plastic compost bins in various sizes available at most garden centres that will suit small gardens, which produce less organic waste. Too often we tend to allocate too little space to composting. You can never add too much compost to your soil, so allocate the biggest possible space you can.
Assembling the materials
A good guide for assembling materials in the correct proportions is to think of them as ‘greens’ and ‘browns’.
Grass clippings, vegetable waste, fresh leaves (nitrogen rich)
Fallen leaves, Straw, Sawdust, Shredded newspaper (carbon rich)
Up to 10% of the material can be rough material like small sticks and prunings that will probably not break down completely but will help with aeration and prevent material from packing down and clogging up. Start by mixing the greens together, chopping up anything that is too big to mix easily. To get the correct proportion of carbon and nitrogen, spread out two buckets of browns and top with one bucket of greens. This is best done outside a container. Repeat the process and then add some ‘sprinklings’. Sprinklings come in many forms, from ground limestone or wood ash to bonemeal. Alternatively one can use commercially available organic compost activator, and then add a few handfuls of soil. Thereafter add water – one to two litres with a fine mist spray or watering can, taking care not to overwater. Repeat this process until all the material is used and then mix the layers together, using a fork, until the material is evenly distributed. Place in the container and turn every 4-6 weeks.
A shredder or chipper is a useful tool to reduce bigger cuttings into small pieces for composting
It is a common mistake to use too much water. Remember that ‘greens’ may not look wet but can contain up to 95% water. The overall moisture content of the compost heap should be 60 -65% – as moist as a wrungout sponge. Not enough moisture is better than too much, it simply means the compost will take longer to mature. Compost can be made in 6-8 weeks, or it can take a year or more. In general, the more effort you put into preparing and assembling the compost heap, the quicker the compost will develop. When the material has turned a dark brown colour and has an earthy smell the composting process is complete. It is then best left for another month or two to mature.
Hints and Tips
- Ensure that your compost heap is covered in wet weather.
- Dry browns (such as fallen leaves) can be kept indefinitely. Collect them in autumn and store in plastic bags.
- Evergreen trimmings and pine needles do not rot well and should be avoided.
- Flies and unpleasant smells are a sign of incorrect compost making, often indicating too much moisture in the mixture. Try adding more ‘dries’.
- Shake as much soil off roots as possible before adding them to the compost.
- Rather send any large quantities of newspaper you have for recycling to make more paper, but small amounts, shredded, and paper towels can be used in compost.
- Kitchen scraps consisting of fruit and vegetables, tea bags, coffee grounds and egg shells can be composted, but avoid animal products and cooked food.
- Do not compost coal, coke ash, cat litter, dog faeces or glossy magazines.
- Avoid using diseased plants.
- A host of small and microscopic creatures create the compost; these are not pests and will not overrun your garden.