Fort Worth gazette. [volume] (Fort Worth, Tex.) 1891-1898, 1891-07-26
AN INCH OF RAINFALL.

Persons who have made careful and in
telligent study of irrigation are pretty well
agreed in the opinion that it would require
water in quantity equaling one inch Of
rainfall, applied weekly, to thoroughly irri-
gate an average but thoroughly prepared
soil to every requirement of ordinary crops.
OF course this presumes that there is no
rainfall to aid the artificial application.
The artificial application of water equal
ling one inch of rainfall, calls for good
deal of water to the acre, but not so much
as many persons suppose. The thing ap-
pears to be one not well understood, and
therefore We find not few expressed opin-
ions widely at variance going through the
public press just now. But the whole
thing is as plain as b if we look at it
Alright through the showing OF few SIM
pie figures.
Not long since correspondent of Farm
and Ranch put 1t that to water an acre of
land equal to one inch of rainfall would re-
quire 153, $40 gallons of water. The state
ment attracted the attention Of Mr.. F. E.
Rooster, special agent of the United States
irrigation inquiry, and seeing that it was
entirely of" he at once proceeded to set
matters right as follows:
An acre covers an area of little more
than two hundred and eight feet square, or
is equivalent to 1850 square feet This
number of square feet is equivalent to
6,212,6i0 square inches. Cover this area
with water one inch deep and you have
6,212, $40 cubic inches of water Now there
are 231 cubic inches in a gallon. Dividing
231 into the 6,212, $40 gives you q, 154 2S-l00
gallons. To cover an acre an inch deep you
will therefore need %, 154 gallons, one quart
and about one gill of water. The amount of
water allowed by your CORES pondent would
be sufficient to place an acre five and SIX
tenth inches under water. ''In actual prac
tice'' your correspondent says he would use
twice this amount of water, to compensate
for wastage and evaporation, or in other
words would flood his land eleven and two
tenths inches deep.
That much water on large acreage
would make flood, sure enough. A sud-
den rainfall to the depth of eleven inches
would indeed be a fearful rain.
This proposition to use double quantity
of water to compensate for wastage and
evaporation further shows lack of clearly
understanding tine case. The irrigator is
not expected to take evaporation and vast
age into account, but to simply give the
land one inch Of water as the rain gauge
would show that it had been given by
shower of rain. One inch of rainfall weekly
would fill every requirement for most soils
if well prepared by pulverization. OF
course there would be waste in case of the
rainfall the same as there would be in
the artificial application. Then in irriga-
ton an application weekly of %. 154 gallons
of water to the acre is all the water we
need.
A good deal is said from time to time
about how much more or how much less
water it takes to wet some soils than 9TH
ers. We regard this as another error. 1t
is not probable that there will be much va
ration in the quantity of water necessary
to thoroughly wet any character of good,
tillable soil. But it is reasonable to sup
pose that some soils might require more
frequent application in the course of the
season than others, on account of difference
in character so far as relates to imbibation
and retention of moisture.