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COMPOST - THE LIVING NATURAL FERTILISER
While there is an enormous list of natural fertilizers, compost itself must
be considered the best and safest all-purpose fertilizer for the organic
garden, but it must be remembered that COMPOST CAN ONLY BE AS GOOD,
NUTRITIONALLY SPEAKING, AS THE ORGANIC MATERIAL FROM WHICH IT IS MADE. For
instance, in a soil that is seriously deficient in magnesium and potassium,
a compost heap which is made only with the plant remains from that garden
will be just as deficient in those elements as the soils that produce them,
and sometimes even more so because what little magnesium and potassium might
have been taken up by, say, tomato plants would be largely concentrated in
the seed, which in turn might very easily find there way into the toilet
from the body, leaving the soil increasingly deficient. A VERY GOOD REASON
TO USE COMPOSTING TOILETS ! )
Well made compost that contains a large number of ingredients from many
different sources will have adequate amounts of all the essential major and
trace elements. The more diversity the better (See Dynamic Accumulators)
The production of humus is the essential first step for the aspiring organic
gardener. In considering any open-composting operation, the speed and
efficiency with which the process progresses depends primarily upon the
amount of material available. In general, it can be said that the bigger the
heap the faster and better will be the composting. Small amounts of material
are not able to maintain the high temperatures necessary for the bacterial
processes to continue efficiently, for a small mass is not self-insulating
and heat is lost too rapidly to the surroundings. Since the availability of
sufficient organic waste for successful composting is the first
consideration. I recommend a minimum size of one cubic meter per pile of
newly made materials.
RIGHT CONSISTENCY
The more finely ground or shredded the organic material, the greater the
surface area upon which bacterial reproduction and activity will proceed and
the greater the evolution of heat.
AIR
An adequate supply of air is necessary for aerobic bacteria to work quickly.
Shredded material including plenty of sticks provides a medium which will
not collapse too quickly and exclude air.
MOISTURE
Probably more compost heaps fail because
of lack of moisture (or sometimes too much) then for any other reason. The
stack should remain moist, but not wet at all times. It should be remembered
that with the tremendous heat generated during the first two or three weeks
of decomposition the mass is likely to dry out very quickly through the
continuous loss of steam.
The heat-generating (thermophilic) stage is critically dependent upon the
moisture content. If the mass becomes too dry, the process will stop very
quickly. On the other hand the process will not proceed satisfactorily if
the mass is poorly drained and too wet.
INSULATION
The retention of heat energy is as important as any other of the essential
elements if good compost is to be made, not only because bacteria multiply
and work much more efficiently at high temperatures, but because the
self-sterilising aspect of composting is also important.
Well-made and well managed compost generates temperatures between 60°C and
72°C. This ensures that the pathogens responsible for many plant diseases,
weed seeds and others diseases that are dangerous to human health are
destroyed. It is likely that a large variety of pathogens are destroyed by
antibiotics produced by compost moulds and fungi of many species, at much
lower temperatures than those mentioned, but it is nice to know that any
pathogens that escape the antibiotics will be finally wiped out by
temperatures in excess of their thermal death points.
Insulation, then, is an important factor in successful composting. Large
compost heaps built in relatively sheltered places are largely
self-insulating, that is to say their outer few centimeters act as a mulch
to the heap itself and no other aids to prevent heat losses may be
considered necessary, particularly if the completed stack is covered with a
few inches of soil. However, one only has to observe the cloud of steam
above a compost heap on a cold still night to realise that some sort of
cover is always useful, particularly in winter. Plastic is quite
satisfactory, especially during very rainy periods when it serves as both a
membrane to prevent heat loss in steam, and a moisture regulator, preventing
excessive amounts of water from entering and 'sogging' the heap, which can
interfere seriouly with the progress of certain important bacteria.
COMPOSTING METHODS
THERE ARE MANY WAYS IN WHICH COMPOSTING CAN BE CONDUCTED.
The choice of the open method to be used is determined purely by the size
and layout of the garden and the personal preferences of the gardener with
regard to appearance, convenience and ease of management. Some prefer to
build a permanent composting area in a selected corner of the garden and
this certainly has advantages in smaller gardens where there is little
choice of site. In larger gardens however, composting sites and methods can
vary from season to season, both
in location and the type of container used, depending upon what is
convenient at the time.
Whatever type of container is designed for rapid open composting, it is
desirable to have at least two and preferably three adjacent compartments to
facilitate both turning and collection of waste in preparation for
composting. A simple but very effective set-up utilises a wall or fence
against which four sheets of corrugated iron are placed at right angles to
provide three 'bins' of whatever width is convenient. In the first bin,
garden refuse is simply dumped progressively as it becomes available,
providing a stockpile for later use- In the second bin, shredded material
(sawdust, grass clippings etc) which has been pre-mixed with manure, seaweed
and rock dust is composted by the method already described. The compost in
the second bin is turned by simply tossing it into the third
bin/so that all the top materials become the bottom materials. After 10 days
to two weeks ,the contents of bin number three are tossed back into bin
number two. For the energetic gardener who is prepared to turn the heaps
every three or four days, large amounts of usable, finished, humus-
laden compost can be made very quickly, requiring only about three to four
weeks. When large amounts of debris are regularly available, and space
permits, a series of five or six such bins allows for a one-direction
operation from bin one to bin five or six so that all stages of
decomposition from fresh material in bin one to humus in bin six are
proceeding continuously, resulting in never ending supply of humus, the work
is not difficult, but demands discipline in regularity of management. |
