Greening your Environment -
Recycle the Waste: Make your own Compost!
By: Jamal Masood
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.
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.
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
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).
Grass Carpet or Sod (matt of grass and
Hair (Both Human and Animal).
Leftover fruits and vegetables including
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.
Cardboard - duly shredded.
Corncobs and cornstalks.
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.
Washing machine lint
Red List (Items which
should not be used)
Coal/Charcoal including its ashes.
Diseased animal’s carcass.
Egg yoke and white.
Excreta of humans and carnivorous pets.
Fish/seafood scraps including scales and
Garden wastes recently sprayed with
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 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
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
Heap should be kept damp not wet i.e. it
should feel moist to the touch when squeezed but should not give off
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
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.