The Black Hills union. [volume] (Rapid City, Pennington County, Dakota [S.D.]) 1889-1904, 1895-03-01
IRRIGATION MATTER.
Evaporation and seepage.

verslty OF Kansas writes the Kansas
Farmer as follows:
Some very interesting and impor-
tant questions were raised by the
papers and discussions on Fridap ct the
meeting of the board of agriculture,
II the space in your valuable paper is
not fully taken, permit me to say a
few words through it. on one of them.
viz, evaporation from and percolation
through soils.
As far as / can learn, no expert
ments have been made in Kansas Or in
the United States to determine the
evaporation from soils or the amount
of water which passes down through
them and ont of the reach OF 'vegeta-
ton. A very complete set5of such x.
periments was. made by Mr.. Chas.
Greaves. nea London, England. be-
tween thesyears 1860 and ls7a. While
the atmospheric conditions are not the
same there: as in Kansas, we may,
nevertheless, learn some important
1actS from them:f aS 49, :. sfsa
-Four .Water-tight. tanks Were usea
in these experiments. One 3A3xa feet
was filed nearly to. the top with. ordi-
nary soil, packed. q little SO as to be. in
the condition Of. ordinary grass land.
A secona one of the same size was
filled nearly to the top of tilter.bed
sand; the other two We're three feet
Square and one'foot deep. To the bot
toms of the first three were attached
tubes which led away the. water that
EeaGhed them to a ImneasuirrfingS vessel.
The third tank served as a, rain-gaugeE,f
and, from. it the rainfall on the other
three was determined Water was
kept in the fourth tank and it hoated,
on the Lee river near by. From it
the evaporation from a water; surface.
was found. Provision, was made to.
catch the run-oHf from the. soil and
sand tanks, but there was none during
these fourteen years.
Nov, the water which passed down
through the soil and the sand was. col
lected and measured, and thus the per-
collation. through each was found. AS
all the rain which fell on the tanks
was either ~evaporated OF passed
through and was measured, the differ
ence pet ween the measured rainfall
and the measured percolation gave tho
evaporation.
"lhe annual rainfall for these four
teen years varied from 15.y IS to 31.l7
inches, the mean being Pot inches.
The mean percolation through soil
was 1853 inches or 20 per cent of the
mean annual rainfall.
The NEAR percolat.on through sanu
was 21.4l inches or SO per cent of the
mean annual rainfall.
1.-The mean evaporation from soil was
1914 inches or II per cent of the mean
annual rainfall.
"The mean evaporation from SAND
was 4.31 inches or II per cent of the
mean annual rainfall.
The mean evaporation from water
was 90 81 inches or so per cent of the
mean annual rainfall.
The evaporation from sand was.
therefore, about one-fourth that from
soil, and the percolation through the
former about four times hat through:
the latter. The evaporation from water
was only slightly greater than tha.:
from soil.
The evaporation from water i 10 west
ern Kansas is about three times that
from water given above. hence, for
the same soil and mean annual rain
fall, we would expect the percentage
evaporation from soil there to be more
than Il per cen of the rainfall, but
the ran falls more rapidly in Kansas
than in England, and hence less water
is left in the soil to evaporate.
"We are apt to under-rate or neglect
evaporation loss. We cannot see the
water as it passes off into the air. We
see it as it soaks away and disappears
into the soil and we strive to make
reservoirs water-tight, but some peo-
pie talk Of building shallow ponds
for storing water, just as though evap.
Grafton loss was nothing.
:As an example of the losses from a
canal, in which no special precaution
was taken to reduce them. we NAV
mention the case of the Perry ditch i,
Clark county. The ditch is eight and
one-half miles long. fifteen feet wide
on top, nine feet wide on the bottom.
two feet deep, and has a grade Of two
and one-fourth feet to the mile.
When water was first admitted to it. II.
was fourteen days from the time the
water entered until it reached the
other end. There were places along
it where the up hill bank had not been
constructed and the ditch widened GU.
into shallow ponds. the area of which
was estimated to be three acres, witt,
an average depth of six inches. From,
this data we n hat about So. sS4, OuG
cubic feet OF water entered the ditch
IN the fourteen days. and 1.iT7,OOC
cubic feet were in the d tch and ponds
at the end of this time. hence, the diff
ference between these. or -, 7O6. O00