Smyrna times., 1893-11-29
Some Special Effects of Tile Drainage.
BY PROF. R. T. BROWN.


lille drainage Is comparatively a new
subject, yet it has attracted so much at
tentlon among agricultural observers
and writers that there remains but lit
tie to be said on the subject that ia
either novel or interesting. Notwitb.
standing this thorough research. there
are facts and phenomena connected
with this subject that appear to he i'm
perfectly understood, or their imnort.
ance overlooked.
lst.-A clay soil finely pulverized
and thoroughly dried will hold from so
TO lOO per cent. of its weight in water
before the same will drip from it. This
water of sub-saturation, known,in COM
mon language as the moisture of the
soil, cannot be reduced by drainage il
can be removed only by vaporatIon.
But at this point the water is adhering
TO the particles of clay are, or should
be, filled with air. This is condition
OF the first Importance in regard to the
fertility Of the soil. But in a state of
saturation these interspaoes are filled
with water and of course the air is ex-
cluded. Now, as this water of satin.
ration can penetrate the sub.soil
slowly, if at all, it must be removed nv
evaporation from the surface. Rnt ss
the surface dries the water from below
rises 0y capillary attraction to FIJI the
place OF that removed, and this leaves
2 partial vacuum, as no air can enter
from below to fill the space of the dis !
placed water. The consequence is
that the softened particles of CLAW are |
drawn together, and by cohesion the |
clay becomes solid mass. or course. |
the lnterspaces thus obliterated dimin. |
ishes the volume OF the clay, and this |
manifested by the gaping cracks that |
show themselves in the CLAW. dried hv
surface evaporation. These cracks
measure the amount of consolidation in
the drying clay. Now If the water can
escape below, the air follows the de-
seending water and fills the pores of
the clay as the water vacates them and
consequently there Is no ooDsolidation
Of tho clay. The admission of air from
ABOVE is an important factor 10 the
Oenenclent influence of tile drainage,
Inu'-Ihis free ventilation OF the
SOL III the secret OF the effect of tiling
"a tlne OF drought. A finely pulverized
SOIL mas power of condensing moist
pre from the atmosphere that circu-
lates freely through It. This can he
readily demonstrated by experiment
iske ave pounds of good soil well
uried ana hpely pulverlsed- -nut 1t Ia
, small basket after carefully weighing
u and expose 1t in some uusheitered
place, on a clear summer night. Weigh
u again IN the morning, and perhapa
you VIII be surprised to find that the
nve pounds Of soil has gained from one
% Two ounces in weight from the wafer !
iosqFned, That is apparently a small
gam, put when we apply the ratio to {
me area OF an acre OF fine soil foot
% depth, It will amount to barrels ~ 7
water. The capacity of air To boid !
moisture is measured by its temnera- !
'ure. Of a clear night the earth Iosss !
peat ny radiation very rapidly. and tbe /
alr entering It, whether from above or !
below, is soon reduced TO the temnera. =
lure OF soil, and of course deposits the 1
Naeerlt was alba to hold at a higher 8
temperature, on the same prineinla i
mat oew ls desposited on grass when
Y is cooled by radiation of heat. Al
Ine depth of three feet or more this ia.
position of moisture is chiefly IN the
lay time, as at that depth surface radi. !
uon Of beat has but little effect. II :
.9e clay is rendered porous hy system +
q thorough drainage the air win pene.
4