The Owosso times. (Owosso, Mich.) 1897-1926, 1905-01-20
A. Visit, to a Nearby King
By c. D: Smith. Of the Agricultural College.
CHAPTER Ill

AS soon as we have begun to examine 1
the soil in place. we have noted that the
soil kernels are rot naked but clothed
with smooth, shining, silver hued gar
ment which clings to them with the
greatest tenacity, accommodating itself
to every irregularity of the surface A
closer examination. of this membrane
like garment shows it to be a tlm OF
water coating the soil kernels over every
part of their exposed surfaces and lining
on side; top and bottom every part OF
the channels between. Il dp not know |
that all of us have',gone; far. enough in
our studies to understand the peculiar
physical force that husholds the water
in the soil, If the soil be fertile and the
water be not in excess, against the sides
of the soil grains, sometimes in opposi-
ton to the attraction of gravitation and
sometimes acting with it.
This force is sometimes called capil-
larry attraction, sometimes surface ten
sion and sometimes something else, but |
no matter what it is called, 1T IS true |
that these soil kernels do attract the
water to themselves and hold 1t over
their surfaces in thin film. You have
noted the same thing every day. You
have noticed how different is the appear
ance of stone when wet and when dry
You have seen how cloth, dipped In
water holds that water in its pores with
out falling out in answer to the attrac-
ton of the earth. Just so the soils holds
the water not loosely in the soil chan
nels, but drawn up against the sides or
the soil kernels and held there with
force that defies the weight of the water
to pull it away. TASK you to remember,
then that the water in fertile soil does
not fill the spaces between the soil ker-
; nels, but exists as film completely en-;
veloping the soil kernels on all sides, top
and bottom, as we'll as north, south, east
and west. Between these water COW
cred soil particles there are left vacant
channels for the passage of air and roots.
9 If the water in the soil be in excess and
!. these passage ways are filled, then there
can none of our crops grow, because OF
the exclusion of the air. Drains must
Il be put in such soils, and the surplus
Il water drawn off, leaving just as mucf
o. as the soil kernels can hold attached K
# their surfaces by this peculiar force tt
o. which we have referred. The amoun
of water given soil can hold ATTACHED
r to the surface of its kernels, will
te course depend, in one respect, on tn
p. amount of surface of all soil kernels ther
st is in a given bulk of the soil. In othe
words if the water. films surroundln
o. the soil kernels are of the same thch
N ness in all cases, the amount Of waite
which a given soil will hold is measure
bv the sum Of the surfaces OF the so
kernels in that soil Another soil woul
"a. hold more or less water than this on
is according to whether there was more
h less surface in that soil to which tn
re. water could cling. 1t becomes nece
sarv, therefore, to study the question
.e9 the total amount of surface exposed
re all the soil kernels in a cubic foot OF IL
we different kinds of soil.
No. If only all the soil particles were pc
ain feet spheres, and we knew how many
I'VE them there were in cubic foot,
arv should have little difficulty in estims
the ing how much the sum OF their ST
the faces would be- We would simply ma
TO calculate the surface OF one su
FRS. sphere and multiply by the number
and the cubic foot and we would have
This Unfortunately for our calculations, I
M soil grains are not spheres, nor DO I'll
,sed act separately, but are joined togetl
into kernels. We must study these X
vest nels therefore as the units. They are
ego all sizes and shapes and the problem OF
in termining the effective surfaces expos
,use 70 which water could cling, seemed
onp- a long time quite impossible of soluti
me Finally Professor Schlicter originate
Jams method whereby it is possible "to de
this mine the diameter of grain, whicf
can substituted for the actual ones, VIC
will permit under IKE condi'iois' 'ne o
oet amount of air or of water to
through" This method does not
here us anything like an exact statemer
the actual surface exposed by all
grains and kernels, but it does CIV
r. the nearest approximation to it tha
have. Using this method it was f'
that the effective diameter of the
kernel in the finest clay was app
no 10 mately one five-thousandth of an
and. that the vacant space in cubic TO
soil was little more than half O
-aven. cubic foot, and that the surface G
three soil grains and kernels in cubic
paint was 173, 700 square feet. In sand!
on the other hand, it was found this
ed off; soil kernels acted as If the average
,heyll eter was ten times as great, or one
hundredth of an inch, while the v
space was about a third OF the
Z Co space occupied by the soil. and tn
hicago face Of the kernels was 11,OSO
A feet in n cubic foot. Prof. King