Recycling of organic waste for the purpose of improving crop productivity and for maintenance of soil quality is of very high economic importance. Composting can be described as a microbiological method that is both safe and non-polluting technique of disposal as well as recycling of organic wastes through the bioconversion of organic wastes to fertilizers.
Composting is indeed a sustainable practice for waste management. This is because it converts large volumes of accumulated organic waste into a useful product. When microorganisms break down organic wastes in a heat-generating environment, numerous harmful organisms are destroyed, waste volume is reduced and there is production of potentially marketable and useful product.
Organic wastes might comprise of animal bedding, manure from livestock operations, kitchen scraps and yard wastes like grass clippings and leaves.
Table of Contents
Composting can be defined as the process by which microorganisms break down organic wastes. Generally, fungi and bacteria are the microorganisms that are responsible for reducing organic waste to much simpler forms. These microorganisms utilize the carbon as a source of fuel. Sometimes earthworms are used and the process is termed as vermicomposting.
The degradation of the materials that contain nitrogen is what causes the breakdown of the original organic material into a product that is much more uniform and that can consequently be utilized as an effective soil amendment. A majority of the unwanted organisms are killed by the heat that is generated by the composting process. Such organisms may include pathogens and weed seeds.
Advantages of composting organic waste include the generation of a beneficial as well as marketable material, elimination of heat-killed pests and reduction of waste volume. The addition of compost to soil greatly enhances its organic matter content and this is quite beneficial. This is because it functions to improve many characteristics of soil and also allows for the gradual release of nutrients for use by crops in the subsequent years.
3 classes of microbes are responsible for the carrying out the process of composing, these are:
- Thermophiles – These are microbes that survive in high temperatures.
- Mesophiles – These are microbes that survive in medium temperatures.
- Psychrophiles – These are microbes that survive in low temperatures.
Generally, the composting process starts at mesophilic temperatures and slowly progresses to thermophilic range.
The ideal particle size for the process is 2 – 3 inches.
Methods of Composting
There are several methods of composting as outlined below:
It is considered to be the most efficient for high quality compost but in a short duration. It demands a high degree of temperature management. It is ideal for the destruction of pathogens, fly larvae and weeds seeds.
It is recommended for the addition of organic matter in eroded areas, in garden plots and around trees. This technique can take up to 2 or more years.
It is done by the spreading organic material on untilled ground or on the surface of the soil and letting it to naturally decompose. It is ideal for roadside landscaping, erosion control, no-till applications and for forage land.
It involves digging a trench that is 6 – 8 inches deep and filling it with organic material up to a level of 3 – 4 inches before covering it with soil. Planting should then follow after several weeks.
How to Compost
There are many materials that can be successfully composted. However, there must be a suitable environment for successful composting to occur. The microorganisms that break down organic wastes carbon as a source of fuel and nitrogen as a source of protein. This means that all organic matter comprises of varying ratios and amounts of both nitrogen and carbon. Nonetheless, the ideal carbon: nitrogen ratio i.e. C: N is 30: 1. This is because large particle size of carbon or simply too much carbon significantly slows down the process of composting.
On the other hand, when there is too much nitrogen i.e. N the temperatures of the compost might rise and this might kill the useful organisms in composting.
When a composting pile is being prepared, the size of the pile is the determining factor of how the entire system will be effectively managed. A small compost tumbler can suffice for very small-scale composting. However, when it comes to large scale composting then it can be achieved by long rows of organic waste. These rows of waste can be moved with the help of tractors that are fitted with windrowing equipment. A bucket loader that is attached to a tractor or manure fork can be used to manage in between piles.
Successful composting is largely controlled by attaining the right composting temperatures. The microorganisms that are required in the process i.e. fungi and bacteria operate at optimum in an environment that is properly aerated, damp and warm. It is impossible for such an environment to exist on the exterior of an organic waste pile. This means that:
- There has to be a sufficient volume of composting organic material to facilitate a warm interior for the fungi and bacteria to thrive.
- The organic pile of waste material has to be turned or mixed up from time to time.
Generally, a volume of 3 sq. feet is adequate to create the desired environment for composting. Nonetheless, if only small volumes are what is available then black containers (popularly known as earth machines can be employed). The black containers must strictly be placed in a location that receives a lot of sunlight.
The turning or mixing strategies in composting are dictated by the available volume of organic material. A small black compost tumbler can simply be rotated on axles or shaken up. On the other hand, larger volumes are usually mixed or turned with the use of a bucket loader or manure fork. Windrows of composting material can be turned using attachments on tractors. Furthermore, the frequency of turning the composting material if function of the material that was used, the microorganisms present in the compost, the weather conditions, aeration conditions and water content of the composting material.
It should be noted that water is essential for the present microorganisms to live as well as work. However, excessive quantities of water can lead to anaerobic conditions that are detrimental to the composting process as a whole. There are several ways of controlling moisture content of the composting material, these include the following:
Watering the pile when it becomes too dry i.e. a moisture content of < 40% or it appears crumbly.
The composting pile can be loosely covered during episodes of rain to prevent it from absorbing too much moisture.
It is also important to know that heat is necessary for the elimination of harmful organisms and weed seeds. The generation of heat is the best indication that the composting process is properly working. The final temperature that is considered to be ideal for composting is 160 F. This means that the pile has to be turned when it attains this temperature to prevent the death of the composting organisms.
The process of composting reaches a conclusion when the compost texture becomes uniform and when turning the composting pile does not result in a rise in temperature. A compost thermometer that is fitted with a long probe is recommended for monitoring the temperature of the interior section of the pile.
The process of composting as comprehensively outlined above does not vary much to that of vermicomposting, the organisms used is the major difference. Compost can be used in many applications i.e. home gardening, landscaping, horticulture and agriculture. Do not pollute the environment now that you know how to recycle waste by composting.
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