The Beaver herald. [volume] (Beaver, O.T. [Okla.]) 1895-1923, 1911-11-30
ESCAPE OF MOISTURE
Conditions Of the Evaporation Of
Water From Soil.
Under Ordinary Conditions II Is I'm
possible TO Remove All Liquid Mat.
ter. fer Small Quantity Is
Strongly Attracted.

Evaporation does not alone occur
from the surface Of free water All
vet or moist substances lose BY evap
GRAFTON most Of the water that they
hold, providing the conditions Of TEN.
I peiature aid relative humidity are IA
yorabie. Thus. from a wet soil. eyap-
orauOn Is continually removing wa.
ter Yet. under ordinary conditions.
I II is impossible to remove all the
I water, for a small quantity Is attract.
ed so strongly by the soil particles
that only temperature above the
bOiling point Of water will drive It
out This part OF the soil is the
Microscopic moisture.
Moreover. Il must be kept in mind
unt evaporation does not occur as
rapidly from wet soil as from a water
s-Tface, unless all the soil pores are
20 completely filed with water that
The soil surface is practically water
surfsce. The reason for this reduced
evaporation from wet soil is almost
seli-evident There is a comparative
ly strong attraction between the soil
ard water. which enables the moist
ure 10 cling as a thin capillary film
around the soil particles. against the
force OF gravity. Ordinarily only cap
illary water is found in well-tllled
sol, and the force causing evapora.
tion must be strong enough to over
come this attraction besides chang.
Ing the water into vapor
The less water there is in the sofl
the thinner the water film, and the
more firmly is the water held Hence
the rate OF evaporation decreases
with the decrease OF soil moisture
This law is confirmed by actual field
tests. For instance, In an average
OF ga trials made at the Utah sta
uon. II was found that three soils
otherwise alike. that contained respec-
lively, 22.63 per cent, i714 per cent.
and 1918 per cent OF water lost in
two weeks to depth OF eight feet
respectively. 214, 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 the dry farmer does not want
his soils TO be unnecessarily moist
The dry farmer can reduce the per
cent. OF water in the soil without dl.
minishlng the total amount OF water
by so treating the soil that the water
viii 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 salt seems to be strong
enough to resist partially the force
causing evaporation. Soil water al.
ways contains some OF the soil ingre.
dents In solution, and consequently
under the given conditions, evapora-
tion occurs more slowly from soil
water. Now, the more fertile the
soil Is, that Is. the more soluble
plant food II contains. the more ma.
terial will be dissolved in the soil
water, and as result the more slow.
ly VIII evaporation take place Fol |
lowing. cultivation. thorough plowine
and manuring, which increase the |
store OF soluble plant food. all tend
to diminish evaporation. While these |
conditions may have little value in
the eyes OF the farmer who is under |
an abundant rainfall, they are OF
great Importance TO the dry farmer
II is only by utilizing every posi-.
bility OF conserving water and fer.
tility that dry farming may be made a
perfectly safe practice.