The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1901-03-28
SOIL AND
PRODUCTS
.Irrig alton Data
In Hawaiian
Group.
REGIONS OF
LIGHT RAINS
Physical Laws Underlying AppIi-
cation Of Water to Crops as
Viewed by DR.. Maxwell.

Irrigation in Hawaii is the subject
of a bulletin prepared by Walter Max
well. director and chief chemist of the
by authority of the Secretary of Agricul-
ture. Mr.. Maxwell discusses the climat-
ic. soil and other conditions as affecting
irrigation in Hawaii and gives the re-
suits of experiments carried on by him
for a number of years. He brings out
some of the most interesting phases OF
irrigation problems in that Territory.
and laws basis for further investiga-
tons of this subject there.
1.-The precipitation of atmospheric mois-
ture." writes Mr. Maxwell, lis very un-
even and irregular over the surface OF
the earth There are zones that are
marked by annual deluges, and there are
vast areas upon which rain rarely fails'
These rainless areas are not confined to
conditions peculiar to specific latitudes,
but are found in the tropical regions of
India and Africa, over the wide plateaus
of North America and in other localities
having widely varying climatic condl-
tons.
"The regions of small rainfall are very
generally distinguished by lands of great
natural fertility. This is due largely, on
the one hand to the absence of great
rains that leach out the elements that
feed plants, and, on the other, TO the
relative absence of crops, which results
from lack of rain. Among the most pro-
Shn or TODAY
regions that were naturally arid, but
which have been rendered productive by
irrigation These tracts include the Pun
lab and other vast districts of India, the
great basin of the Nile in Africa, and
large semi-arid areas that have more re-
Gently been brought under cultivation In
the middle and western United States.
LACK OF RAINFALL.
THE failure of the natural rainfall to
produce crops may be due to the INSULT
cheney of the total precipitation, as In
regions in India. Africa and other lands.
where 1t does not aggregate ten inches
per year; or it may be due to the sea-
sonal distribution, as in other parts OF
India and Africa, in northern Queens
land and some of the Pacific islands,
where a heavy and almost the whole
precipitation takes place within two or
three months.
I'm some localities in northern Queens
land the annual rainfall reaches and ex-
ceeds 100 inches, yet the sugar cane crop
has to lnger through an annual arid pc
Rod which greatly reduces the yield
while upon the Pacific Islands of Ha-
wall, despite the winter rains, many OF
the most fertile lands would be useless
without the prevailing practice Of irriga-
ton Irrigation, consequently, Is playing
an increasingly important part In mod
ern intensive agriculture.
The history of irrigation covers meth
DDS of applying water to crops. including
the crudest efforts Of the peasant ane
the great systems executed by govern
ments or corporations, such as are In
operation in India, the United States and
in the valley of the Nile. Certain OF
those systems are vast, and have been
instituted under the pressure of meeting
great emergencies. Today India Is using
irrigation upo a stupendous scale in
graphing with the calamity of famine.
Economic irrigation requires the con-
sideration of physical laws which were
unknown to the authors of primitive
methods and which have not been gen.
orally observed in establishing the huge
systems of irrigation already mentioned
APPLICATION OF WATER TO CROPS
In discussing some of the physical laws
which underlie the application of water
| to crops and the evaporation of moist
ure from water and soil surfaces Mr.
Maxwell says:
1.-The movement of moisture Is con
stantly going on. The simplest evidence
of this movement Is seen in rainfall and
in the evaporation from water and sol
surfaces.
THE factors that have been given the
greatest prominence as exercising con
| trolling action upon evaporation from
| soil and from the surface of water are
| the temperature and the relative humid
| ity of the air. This view Is amply sus
| tanned If the examination is confined Il
the action of these factors during the
extreme seasons of the year There I:
no question concerning the greater evap
grafton of moisture from soils and wa
| tiers during the months Of summer wher
temperatures are high, and the amount
| OF atmospheric moisture is also rela
| lively small as compared with the beha
| vior of these factors in the colo
season. This is demonstrated in many
| localities by the excess OF water that &C.
cumulates within and upon the soil ir
winter, and the droughts that obtain II
the summer There are localities and
regions. however, that are so fortunate
as to have the greatest rainfall during
consequently OF greatest plant growth
Setting aside the differences concurrent
with the seasons and combining observa.
tons to the relative actions of the sew.
eral factors during the months of sum
mer, it IS then found that the tempera-
ture of the air and the amount of moist
IRE that 1t contains are not the most
dominant factors in the control of evap.
grafton. AS already said, they are fac.
tors, but their combined effects do not
compare with the effects of wind. MOI
| Only In the matter of irrigation but al
so in the location and exposure of res
ervoirs this fact is of leading impor
| lance"
RESULT OF EXPERIMENTS
| The bulletin contains an account of
series of evaporation experiments Under
| the heading Transportation of Moisture
by Vegetation" the bulletin recites:
"The volume of water evaporated from
the soil and the volume transpired b.
the plant during its growth are the con
| trolling factors in determining the tota
water required in the production of
crop, and therefore the quantity of wa
ter to be supplied by irrigation
/