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Vol. 12 No. 3 - July 2006

Greening your Environment - Recycle the Waste: Make your own Compost!

By: Jamal Masood

Introduction:

Compost is  not only an alternative to chemical fertilisers or manure but is also one of nature's best protective covering to increase the soil's water-holding capacity in clay as well as sandy soils thus preventing evaporation of moisture. Compost inhibits growth of weeds, enhances soil quality/fertility, and encourages healthy root development. Micro-organisms feed on the organic matter provided in compost and naturally produce Phosphorus, Nitrogen and Potassium which keeps the soil in a healthy, balanced condition.

In addition to benefiting the plant life, composting also benefits the environment. Compostable materials usually have high moisture content (upto 80%) and incinerating it is not only wasting energy but is also expensive. With increase in population the complexity of waste disposal is spiralling toward a catastrophic situation. The landfills are overflowing, and new sites within an economically transportable distance from the urban areas are getting more and more difficult to find. Moreover landfills pollute both air and groundwater.

As per EPA estimate, the garbage in municipal landfills in USA consists of yard (garden) waste like grass clippings and tree branches, paper and cardboard, plastics, metals, glass, food, and other wastes, out of which about 65 % is organic waste which could be composted. Once we dump our garbage into a landfill we are permanently losing good organic material which could otherwise be composted and recycled. In Indian scenario this ratio could be higher. Our packaging material waste is much less than USA and our vegetative waste is higher because most of the Indians buy and peel fresh vegetables/fruits.

It is therefore time that we give a serious thought to the subject; stop throwing good organic materials and start making our own compost to literally green the surroundings around us, conserving the landfill space and protecting the environment.

Composting at Home

Most of the developing countries like USA, Canada, UK, France, Germany, Australia, New Zealand etc. give wide publicity to composting at home. Their municipal/county/local council offices issue pamphlets and circulars from time to time to encourage the urban population to recycle their organic waste and convert into compost. Metallic/Plastic composting bins, tumblers and wooden boxes for composting and other related tools like pile thermometer, turning hoe etc are readily available in these countries at local hardware stores. Lot of useful information about composting is also available on the internet.

Indian Scenario

Here in India, hardly any thought is being given to composting in urban areas. There is neither propaganda, nor encouragement. It is still felt that we should give a serious thought to this issue and even though the composting tools are not available to us but with limited resources we should still make compost at home. In houses with some open space composting can be done in open pit or trench or heap else it can be carried out in plastic/metallic 200 litres oil drums which can be purchased from market/junk shop. Composting can even be done is a cylinder made of wire mesh or old discarded wooden boxes.

There are two very common misgivings about composting in the minds of most of us, especially those who dwell in flats. These are mainly foul smell and cost factor in composting. But these misgivings are wrong in both the counts. If done properly compost will give a sweet (non-pungent) smell and it is almost free of cost. Needless to say composting will however requires some time and effort on our part.

Composting material

For a compost to be correctly and efficiently formed it is necessary to have right amount of Carbon to Nitrogen (C/N) ratio (approximately 4:1 by volume). Carbon gives energy for maintaining proper heat in the heap and nitrogen for forming protein, the backbone of the macro and micro-organism - the main characters in turning garbage into compost. High carbon will slow down decomposition and high nitrogen, will cause unpleasant odours due to release of excessive nitrogen into the air in the form of ammonia and nitrous oxides.

As a thumb rule, all organic materials which will readily decompose are suitable for composting. Almost all garden/kitchen wastes can be composted. In addition many items which are fully biodegradable like paper, hair, cotton rags, feather etc. can be part of compost. However, there are some exceptions. Meat, poultry, fish, fatty items and milk products can be composted but it is better to avoid these items as these break down quite slowly, cause bad odour/stench and attract unwanted animals like rodents, stray cats and dogs.

Given below is the list of the most common items which can be composted as well as negative list which should not be included. As a convention, the positive list is divided in two parts “Greens” – materials rich in Nitrogen and “Browns” - materials rich in Carbon. The “Greens” also have high moisture content and “Browns’ tend to be dry. To achieve good results, and speedup decomposition, all coarse materials should be chopped or grounded into small pieces before adding to the heap.

Green (Nitrogenous) List

  • Algae, Moss and Seaweed. Rinsed and dried in open air.

  • Bird and Farm Animal droppings/manure. (Avoid fresh dropping also avoid droppings of carnivores).

  • Bread pieces/crumbs.

  • Eggshell.

  • Feathers.

  • Grass Carpet or Sod (matt of grass and grass roots).

  • Grass Clippings.

  • Hair (Both Human and Animal).

  • Leftover cereals/rice.

  • Leftover fruits and vegetables including cooked vegetables.

  • Rotted fruits and vegetables.

  • Tea leaves and Coffee grounds.

  • Vacuum bag contents.

  • Vegetable and fruit wastes e.g. peelings, cores, tops of vegetable like carrot, beet root, turnip etc.

Brown (carbonaceous) List

  • Cardboard - duly shredded.

  • Corncobs and cornstalks.

  • Dead insects.

  • Dead plants.

  • Dry flowers.

  • Nutshells.

  • Paper including newspaper- duly shredded. However it is better to recycle paper then to compost it. Small quantities can always be composted.

  • Plant leaves and trimmings.

  • Sawdust and wood shavings.

  • Shredded untreated wood.

  • Straw and hay.

  • Vegetable stalks.

  • Washing machine lint

  • Wood-fire ash

Red List (Items which should not be used)

  • Coal/Charcoal including its ashes.

  • Dead Animals/pets/birds.

  • Diseased animal’s carcass.

  • Diseased plants.

  • Egg yoke and white.

  • Excreta of humans and carnivorous pets.

  • Fish/seafood scraps including scales and bones.

  • Garden wastes recently sprayed with pesticides.

  • Garden wastes with thorns or toothed leaves, hairy, stinging, or prickly plants including rose cuttings etc.

  • Glossy/Chemically coated paper.

  • Meat, Meat Scraps and bones.

  • Milk and Milk Product.

  • Non Organic material as these not biodegradable - metals, glass, plastics. Stone, lime etc

  • Toilet waste or septic tank sludge.

  • Used Paper tissues.

  • Woody Branches, roots (unless chipped).

Composting Phenomena

Composting is a combination of Bio-chemical and physical factors. To begin with composting is started by macro-organisms who initially chop/grind the organic materials into smaller pieces. These grinders are found in soils and are mainly earthworms, roundworms, hookworms, pinworms, snails, slugs, millipedes beetles, ants, mites, springtails, wood louse, etc. Once the organic material is broken into small particles, the micro-organisms (also known as decomposers) take over. The most effective decomposers are bacteria, fungi, protozoa, and actinobacteria (actinomycetes), These are the Mesophilic bacteria who thrive best at temperatures of about 20 to 40 °C. Given the right conditions of temperature and humidity, these decomposers start multiplying and colonizing in the organic material thereby initiating the composting process.

With the decomposition of organic matter, heat is generated and the central core of the compost pile reaches a temperature averaging about 60 °C. The thermophiles (organisms that thrive at a temperatures above 50°C) take over now and this is when the active phase of composting starts. This is the phase which, if not handled properly, can cause bad odour. For proper and odour free composting it is necessary to aerate the compost so as to maintain adequate supply of Oxygen, lack of which encourages the growth of anaerobic microbes that produce disagreeable odours. Aeration is usually achieved by turning the compost over. Earthworms also improve aeration by tunnelling through the heap.

A secondary but a very beneficial part of this stage is that at temperatures above 50 °C the weeds/disease causing agents (pathogens) like fly larvae etc. are destroyed and compounds which are toxic to plants also break down.

As the Oxygen supply in the central core of the compost decreases it begins to cool. Turning the pile replenishes the Oxygen supply and exposes the organic matter not yet thoroughly decomposed. This results in renewed heat generation and continuation of the thermophilic stage. In due course, the active composting phase subsides, temperatures gradually declines to ambient temperature and turning or mixing has no further impact on temperature cycle.

With drop in temperature, mesophilic micro-organisms recolonize the pile and composting process continues to occur that make the remaining organic matter more stable and suitable for use with plants. This is known as curing stage. During curing, organic materials continue to decompose and are finally converted to biologically stable humus. The final finished product has a dark colour, a crumbly texture and an earthy smell.

Total time for compost to be fully ready for use in plants can be as less as 2 months but to be sure that the compost is fully cured and safe for use, it is better to give it 4-6 months. This however varies from climatic conditions, contents of compost etc. and can be as long as 12 months.

Some Useful Hints:

Any pile of organic matter will eventually rot, irrespective of method used for composting. However there are few important factors which should be kept in mind for achieving good quality of compost in lesser time. These are but not limited to;-

  • In warm areas shelter the pile in a shadier spot so that it doesn't dry out too quickly. In cooler areas the pile should be kept in sunny spot to take advantage of solar heat.

  • In areas which experience heavy rain, a well drained spot should be chosen. If possible pile should be kept under a tree or some sort of shelter to prevent ingress of rain.

  • To allow easy access to the beneficial organism into the pile, it should not be made over hard brick or concrete surface

  • A compost heap should be built up in layers of about 150mm and to distract flies each layer especially the top most layer should be covered with saw dust or wood ash or even plain garden soil.

  • Heap should be kept damp not wet i.e. it should feel moist to the touch when squeezed but should not give off water.

  • Water-logging should be avoided as this inhibits decomposition and will make the compost smell. If it is too wet, absorbent material such as paper, sawdust, straw etc. should be added to the heap.

  • It should be frequently turned so that it is properly aerated and sufficient heat is generated to destroy not only pathogens but also weeds and other seeds.

  • No insecticides should be sprayed over the heap as these will prevent the decomposition process by killing fungi, earthworms, bacteria which are the main players in process of composting.

  • To speed up the process of decomposition, some mature compost, animal manure, or bone meal can be added

  • It may be worthwhile to have two piles so that the material can be build up in one while composting process is taking place in the other pile.

Er. Jamal Masood, a retired Power Plant Engineer is a member of ISEB.

E-mail: jmasood@gmx.net


This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.


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