The Keota news., 1912-05-24
Conditions Of the Evaporation OF
Water From Sod.
Under Ordinary Conditions Il 10 I'm
poosible 70 Remove Al Liquid Mat-
tsr, for Small Quantity 70
strongly Attracted.

Evaporation does MOI alone OCCUR
from The surface Of free water. Al
vst or moist substances lose BY evap-
Grafton most Of the water that they
hold. providing the conditions OF tenn
perature and relative humidity are "a
vorable. Thus. from . vet soil. svap-
oratiou IL continually removing VA
tss. Yet, under ordinary conditions.
1t u impossible to remove all the
water. for . small quantity 10 attract
ed 20 strongly By the soil particles
that only . temperature above the
boiling point Of water will drive It
out This part Of the soil 10 the
hyEroscopic moisture.
Moreover, It must be kept In mind
that evaporation does not occur -
rapidly from wet soil ~ from . water
surface. unless all the soil pores arc
20 completely dlled with water that
the soil surface 10 practically water
surface. The reason for this reduced
evaporation from vet soil u almost
" strong attraction between the soil
and water. which enables the moist
uro TO cling ~ . thin capillary aim
around the soil particles. against the
force Of gravity. Ordinarily only cap
Hilary water II found In well-tilled
sniI. and the force. causing evaposa-
uon must be strong enough to over
como this attraction besides chang
ing the water into vapor.
The less water there II in the soil.
the thinner the water Aim. and the
vnoe> Ne~u1v 4. &hn -etnr h>lHN uon~o
the rate Of evaporation decreases
with the decrease Of soil moisture.
This law IL confirmed BY actual neld
tests. For instance. in an average
Of 174 trials made 1t the Utah sta
ton. II was found that three soils.
otherwise alike, that contained respec-
lively. 22.es per cent. 17.14 per cent.
and 1875 per cont. Of water lost In
two weeks to . depth Of eight feet.
Nspectively. 40. Ill. and 100 pounds
OF water per square foot. Similar
experiments conducted elsewhere also
furnish proof Of the correctness Of
this principle. From this point Of
view tho dry farmer does not want
his soils to be unnecessarily moist.
Tho dry farmer can reduce the per
cent Of water In tho soil without d.
minishing the total amount Of water
BY 20 treating the soil that tho. water
win distribute itself to considerable
depths. This brings into prominence
again the practice Of fall plowing.
deep plowing. sub-soiling. and The
choice Of deep soils for dry farming.
Very much for the same reasons.
evaporation goes on more slowly from
water In which salt or other sub
stances have been dissolved. The At
traction between the water and the
dissolved sat seems to b strong
enough 10 resist partially the force
causing evaporation. Sou water A.
ways contains some oe the soil ingro-
disnts In solution. and consequently
under the given conditions. evaposa-
ton occurs more slowly from soil
watse. Now. tie more fertile the
soil q. that u, the moro soluble
plant food Il contains. the more ma
tsrial WIN b dissolved In the soil
water. and - . result the moro slow
" Win evaporation take place. FOL
lowing. cultivation, thorough plowing
and manuring. which increase thA
store Of soluble plant food. III tsnd
70 diminish evaporation While these
conditions may have little value In
The eyes q the farmer who 10 under
an abundant rainfall. they are Of
great importance to The dry farmer
Il u only By ut1hzing every poss3-