The citizen. [volume] (Berea, Ky.) 1899-1958, 1913-05-22

uon approaches % per cent, while the
mean moisture when plant growth
ceases by reason OF exhaustion OF the
soil huid Is probably less than 10 Def
cent and the difference measures the
store OF water additional TO the cur.
rent rainfall on which the plants may
draw. This difference as per cent Of
four feet. or ~ acre inches-sis tons
per acre. may be denoted the effective
soil nuid OF average soil.
The rate Of soil plant circulation and
the quantity of water passing through
soil and plants during the growing
season are indicated by the exhala ton
from growing plants. A grass plant
VIII In the course OF a hot day erbaie
Its own weight Of water. and a young
leaf OF wheat or rye exposed TO the sun
may even exhale Its own weight 10 an
hour.
The maintenance Of the soil plant cir.
culation required for crop production
generally Involves repea ted additions
OF water during the growing season.
for the effective soil fluid within four
Feet OF the surface would ut the OBJ
served rnte Of plant transpiratic suf.
nee for but meager yield even II the
entire quantity were utilized. 10 ordi-
nary farming the water Is not fully
conserved and applied to plant growth.
30 that practically the ~ acre inches
OF effective soil fluid gro with would not
suffice to produce crop or even per
init any yield Whatever from most
types Of soil. though under certain
conditions water may be drawn from
greater depths In the subsoil than four
feet IL properly cultivated and wa
tered the average acre foot Of soil.
weighing some 1000 tons dncluding
the contained water). retains efficiency
for centuries. but to be even moderate
~ productive this soil must convey to
the crop plants fully is acre feet Of
water. or an amount equivalent to Its
own weight. during each growing sea-
son.
To become effective In plant growth
water must enter the soil body. take
up both mineral salts and organic sub
stances In solution and pass thence
into the plants and on into the air.
This II the normal course Of soil plant
circulation. and the relative ousotftiss
of the sol,d and nuid ma RI. Of the soll
involved In plant growth probably cor
respond fairly with the strength Of
the solution. or one To several hundred.
Pending precise determinations II NAV
be assumed that thu strength NJ thu
solution forming tbe soii ouid and the
ratio OF the solid and ouid parts reouir-
Cd TO maintain en,cIency ara about
equal and something ike / TO 4 600.
\, n.,,r. ,h. ao,. ,.... Itch ,,.
r.,n,.u sr,m .n.r..Ix a,.,,,h,,,.d S.c.,
ana o,h.r d.s.r, nl.n,. 20 ,,,u,,.nt
sors.,. and a. land. ar. hro,gh, IN.
der cul,Iv.,,on tho cron v,s,d. xsrv
from place 10 place and from sea,op 10
season with the rainfall or with the
water supplied nv irrigation. 0ener-
ally throughout the limited States the
actual Yield per unit of WINTER Ia con.
siderably Less than the ratio of drv
matter TO water determined BY plant
oylAl0tiOu. fair TO good CrOD from
an acre a. g.. an acre FOOT OF fertile
soil suppIied with four acre feet Of
water during the year NAV be nut at
a ton OF grain and three tons of slower
and stubble. or four tons In aIl-eouiv-
alent TO l.l3GO of the weight OF the
water With lessenIng of the aggre-
gate water supply (whI n of course
Includes rainfall. accumulated ground
water, subsurface dow aud irrlgation)
the Yield diminlshes more rapidly than
the quantity OF water. virtually ceas-
ing when the supply falls below al
acre foot. while with augmented sup
ply the yield Increases more rapidly
than the water so long as the tillage
and character OF crop are adapted to
full use OF the entire supply.
With present knowledge the ratio "a.
OF course. but a rough approxima ton.
are vague and expert
ences variable, soils differ both In COM
and In the texture controlling
and the Yield OF succulent
vegetables or OF Juicy fruits or fresh
forage may he several times that of |
grain, nuts or dry forage, so that It
will probably be- found needful In time
10 work out ratios for particular crops,