Composting is the biological process of the conversion of organic material of refuse to a usable stable material. This is carried out by the microorganisms present in the refuse. A good mix of browns and greens is the best nutritional balance for the microbes.
Greens are fresh (and often green) plant materials such as green weeds from the garden, kitchen fruit and vegetables scraps, green leaves and tea bags, fresh horse manure etc. The greens have more nitrogen in them. Nitrogen is a critical element in amino acids and proteins and can be thought of as a protein source for the billions of multiplying microbes.
Browns are dry and dead plant materials such as straw, dry brown weeds, autumn leaves and wood chips or sawdust. As such these items are a source of energy for the compost microbes. Because they tend to be dry, browns often need to be moistened before they are put into compost bin construction. This mix also helps out with the aeration and amount of water in the pile.
We use manual as well as mechanical methods for compost bin construction. In rural areas composting refuse and night soil mixtures are dumped together which produce manure for the fields. Layers or vegetables waste and night soils are alternated in a swallow trench. The mixture is turned regularly for about three months to provide air to the mixture. Then the compost is left for another month without turning for the process to take effect. This method of composting is known as the manual method.
In the mechanical process, the waste material is placed in layers about one meter deep. The material is not turned at all but it decomposes completely in about five months. This method of composting is known as the mechanical method.
How to make compost:
- Buy or build a rodent-resistant bin
- Locate the bin on well-drained, level soil.
- Use coarse organic material such as straw or prunings on the bottom upto a few inches.
- Chop material into small pieces.
- Add green nitrogen-rich materials (moist) and brown carbon-rich material (dry)
- Add food waste in the center and cover.
- Aerate the material once a week.
Advantages of compost bin construction:
- It enhances soil nutrients and water retention capacity of soils.
- It suppresses plant diseases.
- It rejuvenates poor soils by adding humus.
- It absorbs odors and degrading volatile organic compounds.
- It helps prevent pollution by preventing pollutants in storm water run-off from draining into water resources.
- It checks soil erosion and silting on embankments.
- It reduces cost through reduction in the need for excess water, fertilizers and pesticides.
Compost bin construction for waste is an aerobic method of decomposing solid wastes. Moisture content is an important factor in aerobic composting. A moisture content of about 55 percent is beneficial for biological breakdown of the waste. It may therefore be necessary sometimes to add water to maintain moisture content.
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Microorganisms help stabilize organic matter. For example, fungi starts working in the first week after dumping of the material. Actinomycetes help in the last stages of the breakdown while bacteria is present throughout the process. The process involves decomposition of organic waste into humus known as compost which is a good fertilizer for the plants. The compost process also produces carbon di oxide and heat which can be used for various purposes like cooking.