In a compost bin, what process leads to the cycling of organic matter?
Composting
This process involves decomposition of a mixture of organic materials to form "smaller bits" of matter called compost. This process does not solely refer to waste matter disposal; information technology also relates to the return of wastes to the soil as part of the cycle of life.
Figure 1: Well-nigh human intervention results in wastes dumped in waterways rather than resumed to the land.
Decomposers:
Majority of decomposers are microorganisms. Macroorganisms such equally earthworms, termites and other insects also aid break downwards organic materials.
Figure 2: Food spider web of the compost pile (D. Dindal)
Composting Parameters
1. Composting materials
a. Good quality compost contains loftier organic thing content and a minimum of not-organic fabric. Some compostable wastes, particularly from industrial areas, tin can contain high levels of metals such as copper, lead, nickel and zinc and should therefore be removed. Other non-organic materials such as glass, plastics and artificial fibers should also exist removed.b. Delicious and immature plants can be decomposed much faster than former and tough ones because they are high in h2o and contain relatively more than sugars.
c. If possible, utilise materials that are high in Due north. such equally residues from leguminous plants because they are preferred by microorganisms since they provide both C and North. They are also easier to break down. The insects, worms, leaner and fungi found in the compost pile do the piece of work of composting.
Composting materials
2. Particle size - The smaller the size of the particles of organic textile, the greater surface area available for set on past the microorganisms. If the particle size is very big, the surface expanse for set on is smaller, and the reaction volition so proceed slowly or may terminate altogether. Information technology is necessary to chop or shred bulky fabric to reduce the particle size to a range of 10-fifty mm.
3. Moisture- All organisms require water for life. The optimum moisture content of ingredients for composting is 50-60 percent. At too depression a moisture content, the biological reactions in a compost heap slow down considerably. Excess water on the other paw, leads to waterlogging of the spaces between the particles of the materials. The maximum practical wet content depends on the structural moisture strength of the materials. For practical purposes the material should be as damp equally a squeezed-out sponge.
four. Aeration -An adequate supply of air to all parts of a compost heap is essential in order to supply oxygen for the organisms and to flush out the carbon dioxide produced. Absence of air (anaerobic conditions) will lead to the development of different types of microorganisms causing either acidic preservation or putrefaction of the heap, producing bad odors.
Aeration is achieved through the natural movement of air into the compost heap, past turning the fabric over regularly.
v. Temperature - When organic textile is gathered together for composting, some of the free energy released by the breakdown of the material is given off as estrus. This causes a rise in temperature. The college the temperature within certain limits, the faster the activity of microorganisms.
At the beginning of the process the textile is at ambient temperature. In the first stage, warming up, the microorganisms nowadays on the materials multiply rapidly and the temperature rises. During this menstruation all the very reactive compounds such as sugars, starches, and fats are broken downward. When the temperature reaches 160°F the fungi stop working and the breakup is continued by actinomycetes and spore-forming strains of leaner. The breakdown slows and the temperature peak is reached. At this menses, the heap is losing as much heat as the microorganisms produce.
When cooling down, the straws and stalks are decomposed, mainly by fungi. This is because as the temperature falls below 160° F the fungi re-invade from the cooler regions of the heap and attack less reactive compounds such equally hemicelluloses and cellulose, breaking them down into simpler carbohydrate compounds, which get available for all the other microorganisms. The actinomycetes too help during this period. At the cease of the cooling down period most of the bachelor food supply has gone, competition starts among the microorganisms, antibiotics are released, and larger soil organisms, especially worms, movement in for a few weeks.
The increase in temperature is one of several factors in the composting process which human action confronting the survival of pathogenic organisms. Tabular array i shows that the common pathogens which cause diseases in humans and domestic animals are readily destroyed at temperatures of 55 to 60°C for periods of a few minutes to a few hours under the moist conditions used in composting.
Experimental Compost Data
Temperature Comparison
Ideal Temperature Curve
Table one. Pathogen survival in composting and agricultural awarding of human wastes
| Organism | Survival in: Composting | Agronomical Awarding |
| Enteric viruses | Killed rapidly at 60°C | May survive upwards to 5 months on soil |
| Salmonellae | Killed in 20 hours at sixty°C | On soil, S. typhi upward to 3 months; other species upward to 1 year |
| Shigellae | Killed in 1 hour at 55°C or in 10 days at forty°C | Up to three months |
| Eastward. common cold | Killed apace in a higher place 60°C | Several months |
| Cholera vobrio | Killed apace above 55°c | Not more than than 1 calendar week |
| Leptospires | Killed in 10 minutes at 50°C | Upwardly to 15 days on soil |
| Hookworm ova | Killed in five minutes at 50°C and 1 hour at 45°C | Up to twenty weeks on soil |
| Ascaris ova | Killed in 2 hours at 55°C 20 hours at 50°C and200 hours at 45°C | Several years |
| Schistosome ova | Killed in 1 60 minutes at 50°C | Upwards to 1 calendar month, if damp |
Source: Wellness Aspects of Excreta and Sillage Management, World Bank, 1980.
six. Acidity (pH)-Compost material becomes slightly acidic at the start of composting due to the simple organic acids produced at the initial stage of decomposition. The heap then turns slightly alkaline later a few days every bit proteins are attacked and ammonia is released. Highly alkaline conditions will lead to excessive loss of nitrogen equally ammonia; accordingly it is wise not to add lime to a heap. Highly acid initial weather condition may lead to a failure of the heap to warm upwards. If conscientious attending is paid to the mixing of materials, moisture content and aeration, at that place is no necessity to influence the pH of the process. The amount of ammonia lost from a compost heap can be reduced by calculation a little soil, about 1% of the weight of the heap.
7. Nutrients-The composting procedure depends upon the action of microorganisms which require a source of carbon to provide free energy and material for new cells, together with a supply of nitrogen for cell proteins. Nitrogen is the virtually important nutrient and, in general, if sufficient nitrogen is bachelor in the original organic affair, most other nutrients will also be bachelor in adequate quantities. It is desirable that the ratio of carbon to nitrogen (C/N) is in the range of 30-35/l in the initial mixture. If it is much college, the process will take a long time before sufficient carbon is oxidized off as carbon dioxide, if it is lower, and so nitrogen, which is an important fertilizer component of the final compost, will be given off every bit ammonia. The simplest method of adjusting the C/N ratio is to mix together different materials of high and depression carbon and nitrogen contents. For case, straw materials which have a loftier C/N ratio can be mixed with materials such as manures which have low C/N ratio.
References:
Bautista, O.One thousand. et al. 1983. Introduction to Tropical Horticulture. pp. 205-206
Cosico, W.C. 1985. Organic Fertilizers: Their Nature, Backdrop and Use. pp. 39 - 50
Dalzell, H.W. et al. 1987. Soil Direction: Compost Production and Employ in Tropical and Subtropical Environments. FAO Soils Balderdash. 56: 22-27,162.
Source: http://www.nzdl.org/cgi-bin/library.cgi?e=d-00000-00---off-0fnl2.2--00-0----0-10-0---0---0direct-10---4-------0-1l--11-en-50---20-about---00-0-1-00-0-0-11-1-0utfZz-8-00&cl=CL1.1&d=HASH018f0698116ebe8c31aa6a96.4.5>=1
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