adminWASTE management has become one of the environmental challenges that the country is facing. Thousands of tonnes of solid waste are generated daily in the country and estimates show that in 2011 Harare generated 170 million tonnes of waste (Institute of Environmental Studies, 2012). Most of it ends up in open dumps and wetlands, contaminating surface and ground water and posing major health hazards. This has greatly exposed the general public to disease outbreaks which have been recorded in recent years.
According to the World Bank estimates of (1992), between 0,4 to 0,9kg is produced in the cities of developing countries per capita per day.
Changing lifestyles and consumption patterns pose special waste management challenges, as waste management systems in developing countries are incapable of frequent adjustment to match these lifestyle changes.
The bio-degradable component of domestic waste constitutes 72 percent of waste generated nationwide. The composting of such waste by households would massively reduce solid the amounts of waste that ends up in landfills and ease the burden on municipalities. Reducing waste in communities will improve the environment and contribute to a better quality of life as shown.
How can we reduce waste?
Backyard composting: Composting is a technique used to accelerate the natural decay process. The technique converts organic wastes to mulch which is used to fertilise and condition soil. Composting increases the lifespan of landfill sites and cuts on the local authorities’ refuse collection expenses, which could in turn improve service delivery. One can easily make compost with landscape trimmings and food leftovers in the backyard. With a small investment in time, you can improve the health and appearance of your yard, save money on fertilisers and mulch, while preserving natural resources and ensuring that we live in a clean, safe and healthy environment.
Composting requirements: Shredded organic wastes. Shredding or chopping materials hastens decay. One way to shred leaves is to mow the lawn before raking.
Good location: The compost pile should be located in a warm area and protected from overexposure to wind and too much direct sunlight. While heat and air facilitate composting, overexposure dries the materials. The location should not offend neighbours.
Nitrogen: Nitrogen accelerates composting. Good sources include fresh grass clippings, manure, blood meal and nitrogenous fertiliser. Lime should be used sparingly if at all. It enhances decomposition, but too much causes nitrogen loss, and it usually isn’t necessary unless the pile contains large amounts of pine and spruce needles or fruit wastes.
Air: The compost pile and its enclosure should be well ventilated. Some decay will occur without oxygen, but the process is slow and causes odours.
Water: Materials in the compost pile should be kept as moist as a squeezed sponge. Too little or too much water retards decomposition. Overwatering causes odours and loss of nutrients.
Building an enclosure: Enclosing the compost pile saves space and prevents litter. The enclosure should be collapsible or provide an entry large enough to permit the pile to be turned. It should be at least 1 metre wide and 1 metre tall, too much weight causes compaction and loss of oxygen. The enclosure can be built of wood, pallets, hay bales, cinder blocks, stakes and chicken wire, or snow fencing. Prefabricated compost bins are also available.
Building the pile: Aside from the basic requirements for decomposition and preventing odours and other nuisances, there is no set method for building a compost pile. One technique may be faster than another, but a variety of methods work well. Piles can be built in layers to ensure the proper proportion of carbon (e.g., leaves, woody materials) to nitrogen (grass, fertiliser), but the layers should be thoroughly intermixed after the pile is built.
Maintenance: Turning and mixing the pile with a pitchfork or shovel, or shifting it into another bin, provides the oxygen necessary for decomposition and compensates for excess moisture. A pile that is not mixed may take 34 times longer to decompose. Composting can take as long as a year or as little as 14 days, depending upon the amount of human control. Recommendations for mixing the pile vary from every 3 days to every 6 weeks.
More frequent turning results in faster composting. Odours indicate that the pile is too damp or lacks oxygen, and that more frequent turning is necessary. Occasional watering may be necessary to keep the pile damp, especially in dry weather. Covering the pile with black plastic reduces the need for watering; it also prevents rainwater from leaching out the nutrients. A pile that is decomposing properly should generate temperatures of 140°-160°F at its centre.
The heat kills most weed seeds, insect eggs and diseases.
The pile should be turned when the centre begins to cool. Turning the pile maintains the temperature and ensures that all material is exposed to the centre heat. When the compost is finished, the pile will no longer heat up. Small amounts of fresh materials may be added but should be buried inside the pile to avoid pests and speed composting. It is better to add fresh materials to a new pile.
Managing your compost
Problem: Rotten egg smell
Cause: Insufficient air or too much moisture
Solution: Turn pile and incorporate coarse browns (sawdust, leaves)
Problem: Ammonia smell
Cause: Too much nitrogen
Solution: Incorporate coarse browns (sawdust, leaves)
Problem: Pile too small
Solution: Add more organic matter
Cause: Insufficient moisture
Solution: Turn pile and add water
Problem: Lack of nitrogen
Solution: Incorporate food waste, grass clippings or manure (chicken, rabbit, cow, horse)
Problem: Not enough air
Solution: Turn pile
Problem: Cold weather
Solution: Increase pile size or insulate with straw What not to add to a compost: Aluminium, tin or other metal, dairy products, fats, grease or oils, meat or seafood scraps, pet wastes, soiled diapers, plastic, stickers from fruits or vegetables, yard trimmings treated with chemical pesticides, coal or charcoal ash, treated or painted wood
Finished compost
Finished compost is dark brown, crumbly, and has an earthy odour.
Depending upon seasonal temperatures, a well-built, well-tended pile generally yields finished compost in 2 weeks to 4 months. An unattended pile made with unshredded material may take longer than a year to decompose.
Why compost?
- It’s earth friendly: Food leftovers and yard waste make up a significant amount of the waste stream. Making compost keeps these materials out of landfills, where they take up space and release methane, a greenhouse gas 21 times more dangerous than carbon dioxide emissions in the atmosphere.
- It benefits your yard: Compost improves the soil structure and texture, increases the soil’s ability to hold water and air, improves soil fertility and stimulates healthy root development in plants.
- It’s easy: You can start with just leaves and grass, then work your way towards composting food leftovers.
- It saves money: Adding compost to your garden can reduce or eliminate the need to buy chemical fertilisers or compost. Those that have engaged private waste collectors, composting can cut down waste disposal costs.
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Online Reporter
Bongani Ndlovu