The Cambria freeman. [volume] (Ebensburg, Pa.) 1867-1938, 1888-08-03
Caplllarity or Soil.

! Ut. r. LEWIS SturteVanV- IN usIuR
and explaining the term ''capillarity OF
I the soil, ~ has formulated into doctrine
what has been observed and desultorily
taught through generations. The old
writer's insist on fine tillage, a rendering
of the soil into fine tilth-eveuly gran
ulated all through-and the famous ex-
ploits of Tull, and of Smith, of Lois
Weldon in producing heavy crops con-
tinually without manure on heavy clay
soils, were results of this intimately
fine working of them. A soil may be
called capillary when so finely divided
(yet without being ground into powder
-impalpable) as to resemble the finest
ssnd, the PARTICLES of which, as one
may see in a heap of broken redstone,
lie in close contact, yet everywhere
leaves spaces communicating so as to
allow water or air free passage. When
We take up handful of damp loan and
press it it falls apart again almost as
readily as the fine Sc nd, vet not wholly,
because the particles hold to each other,
when once quite near by the attraction
of cohesion. This same attraction also
allures the water. as is distinctly seen
when one end of glass tube of any CAL
iber las piece of a broken thermome-
ter tube) is dipped vertically in colored
water the water will be seen rising
quite far up the narrow interior and
even drawn up against the outer face of
the glass as far as a one-sided pull can
take it. a lump of white sugar with
it's base just barely touching the same
water will Immediately draw it to the
top, ascended through the interstices.
A dry clot of capillary soiI-loam-will
take up the liquid similarly. If the su-
gar is compacted into candy, or the soil
into dense clayey lump, this bea utiful
effect car not occur. Too finely pow
dered ioam. as road dust for example.
wetted into a dough and then dried,
will be too compact to admit of it.
And if We crush this dried cake or the
cake of clay into coarse fragments, the
inteIstices will be too wide for the pow
er of attraction to reach arcross aud
the water will fail TO climb up. 1t is
like a cbimney-sweeP of the olden time
who could mount up a flue with back
against one side, and hands and knees
against the other, but would fail in
chimneys too wide for such a means Of
ascent.
This principle underlies all soil-work-
ing, and should guide continually In the
management OF heavy soils. 1t accounts
for the better success with wheat or
rye sown on corn stubbles without re-
piowing. The sod that was turned
down in the spring for corn renders
the soil, by the end of September, in
the best condition of capillsrity, but il
we plOw it again, teaIing out the thick
corn roots, we can not restore that
same equally fine condition but leave
roots which both cut off the capillary
ascent OF moisture and by becoming
filed with stsgnant, damp air, form
chambers Cor the growth Of molds that
are poisonous to the plant roots. The
supply OF moisture to feeding roots of
plants from below is superior TO sur
face irrigation supply In at least three
respects First, it is comparatively in
expensive. Nex., it feeds the roots as
we'll as supplies water to convey the
food for the salts tha: dissolve into the
soil water at whstever depth, rise with
it to the surface, and it is only there that
they separate, as only the pure vapor Of
water can take wing and rise among
the PARTICLES of air like as the solution
did through the PARTICLES of earth. In
dry autumnsl weather we often see tie
surface visibly coated with deposited
salts left behind in this way. Water
or irrigation may bring with it some
nutrimert in solution, but it is very
often the case that it's excessive flow
carries this means of fertility beyond
the reach OF the plants, if IT does not
even carry some of the soil away too.
Much of the good effect OF irrigation
on dry Western soils results from its
dissolving salts left at the surface and
conveying them down again within the
reach o. the absorbing root-points.
This brings up a third great merit of
this capillary supply of the constantly
needed water-that its supply is con-
stant as long as there is water below
and within reach of the capillary struc-
ture of the soil, and also that its supply
is never in Injurious excess