It is customary, when writing of any crop culture, to give precedence
to site and soil, but in the case of cacao these considerations are
of secondary importance, and while none of the minor operations of
planting, pruning, cultivation, and fertilizing may be overlooked,
they are all outweighed by the single essential--climate.
In general, a state of atmospheric saturation keeps pace with heavy
rainfall, and for that reason we may successfully look for the highest
relative humidity upon the eastern shores of the Archipelago, where
the rainfall is more uniformly distributed over the whole year,
than upon the west.
There are places where the conditions are so peculiar as to challenge
especial inquiry. We find on the peninsula of Zamboanga a recorded
annual mean rainfall of only 888 mm., and yet cacao (unirrigated)
exhibits exceptional thrift and vigor. It is true that this rain is
so evenly distributed throughout the year that every drop becomes
available, yet the total rainfall is insufficient to account for
the very evident and abundant atmospheric humidity indicated by
the prosperous conditions of the cacao plantations. The explanation
of this phenomenon, as made to me by the Rev. Father Algué, of the
Observatory of Manila, is to the effect that strong equatorial ocean
currents constantly prevail against southern Mindanao, and that their
influence extend north nearly to the tenth degree of latitude. These
currents, carrying their moisture-laden atmosphere, would naturally
affect the whole of this narrow neck of land and influence as well
some of the western coast of Mindanao, and probably place it upon
the same favored hygrometric plane as the eastern coast, where the
rainfall in some localities amounts to 4 meters a year.
While 2,000 mm. of mean annual rainfall equably distributed is ample
to achieve complete success, it seems almost impossible to injure
cacao by excessive precipitation. It has been known to successfully
tide over inundation of the whole stem up to the first branches for
a period covering nearly a month.
Irrigation must be resorted to in cases of deficient or unevenly
distributed rainfall, and irrigation is always advantageous whenever
there is suspension of rain for a period of more than fifteen days.
Concerning temperatures the best is that with an annual mean of 26°
to 28°, with 20° as the mean minimum where any measure of success
may be expected. A mean temperature of over 30° is prejudicial to
cacao growing.
The last but not least important of the atmospheric phenomena for
our consideration are the winds. Cacao loves to "steam and swelter in
its own atmosphere" and high winds are inimical, and even refreshing
breezes are incompatible, with the greatest success. As there are but
few large areas in these Islands that are exempt from one or other
of our prevailing winds, the remedies that suggest themselves are:
The selection of small sheltered valleys where the prevailing winds
are directly cut off by intervening hills or mountains; the plantation
of only small groves in the open, and their frequent intersection by
the plantation of rapid growing trees; and, best of all, plantings
made in forest clearings, where the remaining forested lands will
furnish the needed protection.