The Preparation of Plantation RubberMorgan, Sidney
Science
The Preparation of Plantation Rubber
Morgan, Sidney
Rubber
Planters with original views, and of an enquiring nature, often query the
common practice; and it has been suggested that "as the latex descends by
the force of gravity," one's paring should be done in an upward direction,
thus obtaining a greater pressure of latex--and hence a greater flow. It
will be obvious that it would be no simple matter to collect effectively
the latex thus obtained from the under edge of a sloping cut, but apart
from this the argument would appear to be founded upon what is now accepted
to be a fallacy--viz., that the latex _per se_ is manufactured in the
leaves and gravitates down the tree.
FORMER SYSTEMS OF TAPPING.--To hark back ten years in the plantation rubber
industry is equivalent to delving into history, since development has been
so rapid. It was then thought necessary to place upon the trees a number of
simultaneous cuts which the modern planter would judge to be inconceivably
excessive. Were it not for evidence in the shape of photographs extant, it
would be difficult to convince a young planter that such systems were
employed.
It was not uncommon for trees to have from six to ten cuts, sometimes all
placed on one half of the tree in a herring-bone fashion, and sometimes
divided into two portions, each of which tapped the opposite quarter panel
of the tree's circumference. Such superimposed cuts were spaced from 1 foot
to 18 inches apart.
On other occasions, a spiral cut was employed, commencing at a height of,
say, 5 feet, and gradually descending to the cup at the base of the tree.
Later systems varied from several cuts on a half-circumference, or on a
quarter of the tree, tapped either daily, or on alternate days, to cases in
which one-third or one-fifth of the tree was employed. Also popular were
the systems of the [V] and half-spiral cuts on half the circumference.
It did not take long to be recognised that with all these systems demanding
a number of simultaneous parings from the same panel of bark, the rate of
excision was so heavy that the period available for the renewal of bark was
insufficient for continuous tapping.
As a result most of the systems specified have fallen into desuetude, and
the tendency has since been to reduce the number of cuts, or the
periodicity of tapping, so as to allow for increasing periods of bark
renewal.
In the earlier days, a period of four years was thought to be an extremely
generous allowance, whereas six years is now becoming recognised as a
minimum necessity. Eight years is not regarded as extravagant, while with
older bark on some estates periods of ten and twelve years have to be
allowed for full renewal. Even so no finality has been reached, and no
general rule can be laid down. Local conditions of planting and growth
exercise great influence, and the writers have in mind instances in which a
period of eight years has proved to be insufficient even for a first
renewal after the excision of virgin bark.
Public-domain text, read in full here on John Shaqi.
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