The Brownsville daily herald. [volume] (Brownsville, Tex.) 1897-1910, 1909-06-18
$3.50 l.l.al. 80 8 80 ...s.sA..4
DRAINAGE IN THE
RIO GRANDE DELTA
To The Herald:

10 L u6 I16Idiu
The early part of the present year
it was decided by the chief of drain
age investigations, Office of expert
ment stations, U. S. Department of
Agriculture to station a drainage en-
gineer in Texas with headquarters at
Brownsville The work of this Office
is educational in nature and informa-
ton is given to anyone needing adj
vice on drainage problems, no charge
being made for such services. Where
small tracts have become water
logged or swamped assistance will be
given to those making application
This assistance will consist of such
surveys as may be necessary and
plans for the drainage of the land.
Extensive surveys are not contemplate
ed but where such surveys have been
made, and il is so desired, this office
will check over the plans and consult
with the engineer in charge and with
the board of drainage commissioners.
A few of the fundamental prinei-
pies of the movement of water and
mineral salts in the soil may well be
considered, in order that the agricul-
turist may understand the problems
he may have to solve.
Water in the soil is usually divid-
ed into two classes, hydrostatic water
and capillary water
HydrOstatic water is that which
occupies the large spaces between the
particles of soil, and is free to respond
to the forces of gravity when an outlet
is provided 1t is the water that is
visible when land becomes water
logged or swamped, and is called
gravity water or drainage water
Capillary water is that which clings
closely to the particles of soil by a
force called surface tension, and is
not affected by gravity 1t is the
water that remains when land is
drained.
Soil is composed of a great many
small particles and the openings or
vOids between them vary from 80 to
65 per cent of the whole space Occu-
pied by a given amount When there
is only small amount of moisture in
the soil the film of capillary water
surrounding each particle is very thin,
but as water is added it thickens up
until finally the voids are filled, and
practically all of the air is excluded.
Plants get their nourishment from
the mineral matter, organic matter,
and gases held in solution by the
capillary water, but since air is ne
cessary for the formation of plant food
it is readily seen that if the voids are
filled with water the plant cannot exist
HydTOstatic water moves along the |
line of least resistance under the |
force of gravity, but capillary water
moves in any direction due to the at /
traction that exists between solids /
and liquids
The mineral salts alkali) of de- |
composed rock are found in varying
quantities in all arid and semi-arid /
countries. In the Rio Grande Delta |
the alkali is distributed through the |
soil by nature in such a manner that |
in most cases it is not injurious to |
crops, but it is a noticeable fact here |
as in other irrigated countries that /
when an excess of water is allowed to |
stand on the surface, enter the /
ground and be ev3ported from the
or seep through a sub-strat-
face, alkali is liable to accumulate
N sufficient quantities to lnjure Pant
growth. Provision should always be
made to carry away the surplus
irrigation and rain water. and fields
should be carefully watched to detect |
he first signs of seepage Perhaps
he most prolific cause of the concen-
ration of alkali is seepage water.
Water moving through the soil dis
solves and collects a large amount of
mineral matter and when brought to
he surface by capillary action, evap--
rates. leaving the salt on the sur
ace where in time it may accumu-
ate to the detriment of plant growth. /
;eepage water should always be cut
'ff before harmful water-table is
ormed. 1t has been the experience
# the engineers of this office, in the
Western states under conditions much ,
he same as in this valley, that no
harmful accumulation of alkali will
'ccur when the water-table can be
leld 5 feet below the surface.
The movement of mineral SaltSi in the !
oil is usually in the direction of the {
apillary water. When water is ap- !
lied to the surface it passes down ,
yard through root channels, worm ,
and cracks in tn soil, but !
Then it is drawn in any direction by :
urface tension it passes through the !
mallest capillary openings in the
oil. AS it is drawn up by vapora- !
ion it brings with it in solution some :
f the mineral salts that were con- !
aimed in the small openings and not !
lolested by the water in its passage >
Onward. 1t is therefore evident ,
hat, to prevent the alkali concentrate
lg at the surface, it is necessary to
ut more water downward through
be soil than is allowed to come up t
trough it. And to do so, either a
atural or artificial deep drainage is
ecessary. Where there is not good '
cultivation and the forma- l
ON Of Io1, u-ilI Ior.o,, r