Clarke courier. [volume] (Berryville, Va.) 1869-1997, 1909-02-03
Home Course In
Modern Agriculture
N.-Water In Its Relation to Plant Growth
By c. v. GREGORY,
agricultural Df0fSfon. Eoeva State College
by Amer Press
WWYE have already learned some

wv YE have already learned some
&$As thing OF the value OF water
" as plant food. This is
only one OF it's minor uses.
however. In addition TO the water
which is decompcSed by the plant and
used I'm making starch and other prod.
ucts. many times as much is used Tor
other purposes. one OF the principal
81 these Is dissolving plant foCd aud
carrying Il upward 60 the leaves Aft
er reaching the leaves most 81 the wa
ter is evaporated. leaving In the leaf
cells the materials which Il brought
up.
The cells OF which the leaves are
made are very delicate aud depend for
their stiffness on the water which they
contain. Without this water they
would collapse in the same way BIZ
cycle tire does when the air IS let out
This is the very thing that happens
when the leaves wilt The rire 81
water from the roots has been checked
I'm some way. and as evaporation sim
continues the leaf cells become partly
emptied and shrink up
The leaves are not entirely Iplcss
nj such n time. however. ON On p side
Of the tiny pores on the unders.de OF
the leaf IS 4 cell known as n cuagd
cell. When the supply III moisturc
begins Co fail. these guard cells shrink
up and i'm dainE So close the openings.
thus checking evaporation In some
plants. like corn. the leaves curl up ut
such n time thus still further les en-
ing the rate OF evaporation. or course
when a ieaf il wilted IN this manner
the work OF building up plant tissues
is seriously checked Tiis often hap
pens during the dry weather OF Sally
and AUGUST when the soil lcgo.lc.i so
dry that the roots have al Guilty I'm
obtaining tie needed mcis.n are. The
checking OF development, which results
often reduces the yield OF corn as
much as twenty Co thirty lushels per
acre and that Of other cvusts in pro-
portion. For every POURED of dry
matter In a iHatrre plant 1rrn 3.) 20
500 pounds o. wafer have brcu brought
ur u the roots and cvSvci I'D from
the leaves. one of the most imlor-
tant factors IN the production Of a
maximum crcp Is the maintenance OF
plentiful water supply within casy
reach OF the roots
There are three classes of water I'm
the soil. The FIRST is Known US GROUND
water and is that water which col.
lccts in a hole dug In "a wrt SCH or
runs OF through the tile ~ Jrliaed
land. The second is the capillary
water and is that which l. lert be-
tween the soil PARTICLES after the
ground water has been drawn OF.
The ground water is affected 10y grav-
itation. while the capillary water Is
not.
II sample OF soil that looks per
fectly dry IS placed In an oven and
heated for some time Il will be found
that Is has lost considerably ia weight.
owing To moisture being driven of.
This Is the third class. or microscopic
moisture This. OF course. is of no
value 10 the plant. since the roots
cannot extract moisture from an air
dry soil. Neither can they uec the
ground water. This Is rcgily n dam
age I'm the upper two or three feet OF
soil, since IL $50 fills the Sfaccs that
the roots cannot get enough air
During rain the grcurd water
passing through the soil draws con-
siderable air with Il. A. soon as the