Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1871-10-06
How do Drains Operate ?

After conversation with various Practical
/ farmers. | am satisfied that many of them do
/ not fully understand the correct theory of the
action of drains. To those who do not give
/ the matter their careful attention, it Will
/ seem very simple matter to understand
| how, when it rains, or when from slme other
cause water accumUlates in the soil. it should
escape BY sinking down into q well-made
drain but just here is where mistake Is
made, for the water does not cone in
from the top. but from the bottom Of
the drain or, in other words, the surplus
water comes up into the drain, and not down
| into iJ. In all low lands there is point az
which the soil remains saturated with water,
and the distance Of this point from the sur
face Will of course vary with the facility
offered for the discharge ofthe surplus water
Where this point is so near the surface as 10
affect the roots Of the farmer cops, drains
are needed, and should be used, in order %
keep this line Of saturati0n on q level with
their bottoms. In order TO simplify the
matter, this line Of saturati1n has been STYLED
the water table. In case Of heavy rain,
the water viii sink down until 1t reaches this
water table, which. from the accumulation IF
water, will gradually rise until (in the ab-
sence Of drains) it finds a natural outlet
The amount Of damage done to the farmer will.
Of course, depend upon tie height OF this out
let in some cases It is So high as 70 overflow
the surface, and in 0the r. will not reach the
surface, but still is high enough 70 do damage
to the growing crops.
To explain more clearly mv meaning. sup
pose barrel (watcr-ti ,hD to be filed with
common soil, and small openings made at
different heights along Its side; now suppose
water TO be poured 50 slowly upon the sur
face Of the soil that it viii be absorbed as
fast as it is poured in.-the earth Will reach
point Of saturation a which it will hold
no more water, and it will accumulate atthc
bottom of the barrel. lfthc addition Of wa
ter is continued, the artificial water table will
rise, and tho surplus wa.er will pass Of at
the loves. opening f the wafer Is added
faster than one opening can carry it oa, it
will rise to the next above. and in this way
will, # the water is add Cd fast enough, over
flow the top of the barrel In all cases the
surplus water will rise o the lowest opening,
and not fall to and esca- )e by the upper one.
This Is exactly what tai ;es place with drain
As soon as the drain is opened it lowers the
water table to its own sye. and il the water
does not come in faster than the drain can
carry it of, will hold it there.
In one case was told by Yractica' farm
er, who had drains in successful operation,
that this idea was not correct. for if it was,
one drain would lower the water table on an
acre of ground, and should prove sufficient to
drain it properly. But for :he capillary at
traction Of the soil, this objection would hold
good. Different soils possess the power Of
holding water in different Cegrees and hence
no rule for spacing drains will hold good
they may be, and oft en- are, 50 far apart that
the capillary attraction Of the soil entirely
counteracts the tendency Of the water 10 seek
the level Of the drain; and hence we find
where the drains aIe too far apart, that the
water table is not level. but rises nearly or
quite to the surface. midway between the
drains. but over them falls to their level.
This line Of satnrauon Is a wonderful pro-
vision Of nature, whereby loisture is fur
Hished Just as it is needed, nd in proper
quantities, provided it is at le proper dis
lance from the surface If th is point is too
far from the surface, the powc of capillary
attraction will be overcome by the weight OF
water,-and if TOO near the eu face. the crop
will be injured by its roots con ing in contact
with the water.
From what have already written. we
may see why drained land IS so much less
liable to wash than that which is undrain-
ed,-for the water having a free passag
through the soil to the level of the water
table, will pass of in the drain instead of
over the surface Of the oil.--Praciicqi
farmer.