The news and herald. (Winnsboro, S.C.) 1877-1900, 1881-02-05
tFoR THE NEWS AND HERALD. ]
SCIENCE IN FARMING,

Agricultural Geology, with Wiso Hints to
Farmers.
Geo. Fl. McIIdster, ESQ.,:
AS tho schools Of our day taught lit
tie of chemistry and geology, though
these sciences are highly necessary to
understand the formation and con-
struction of soils, and as we are not
professors but homcspun turner's, we
will claim the privilege Of using our
Eomcspun language in what we have
to say Oh this subject.
Tho outer surface Of the earth is
generally covered with loose or soft
matter, in coMtradistinction to solid,
as rocks. This sand, clay, etc., is
formed from rocks, either by disinte-
grafton, decomposition or by having
been crushed, ground or abraidcd by
some natural cause. 70 the extreme
outer or upper crust Of this coating,
constituting thickness generally of
from one to several inches, we apply
the term soil. 10 tho next inner crust
Of ono to several feet we apply another
term, subsoil. Still another term may
be applied to the layer under the sub
soil, Of from fifty to one hundred feet
thick. This is substratum, and this,
like the subsoil, has very important
bearing on the character and availabili-
ty of the soil.
If the subsoil is too porous valuable
ingredients may sink into 1t and be
lost to plants. If it is pure or pipe
clay, it will be too stiff and impervi, us
to water, and will keep the soil from
draining in Il natural way and throw
ing oil its supcrfluous water. Since it
i Il ilicult to undcrdraw such soils
properly, they arc generally of little
value, save when sufficiently rolling
to afford lateral drainage.
If the substratum, or rock, be strait
fed horiz ntally, and this rock is Of
such character as to be impcrvious to
water and to afford no seams through
which the same can sink, and especial
~ If this rock comes near the suriucc,
this Substratum will always act as a
barrier against perfect and successful
drainage. If, on the contrary, the
substratum is of porous earth or rock
h""in" considerable inrlnatinu or din.
seams through which water can pr:cu-
late, then such snbstrntum answers
the purpose OF perfect understandings
and the lands Supcrilnposcd on them
arc available for Improvement at no
cost ior drainage purposes. Such
natural undcr-dlnila"c is supplied to
many OF our best farming lands.
AS remarked before, all snils are
formed from rock. and all par;nkc of
the nature Of the rock from which they
are formed. AS there ARE no great
number of different rLcks, il we
know from what kind Of rock pur-
;icular soil is formed we cam readily
presume what may he its principal
constituents. But soils arc either soils
OF subsidcnce or soils Of transport
BY soils Of subsidcncc we mean the
dccomposcd or disintcgrated portions
OF rocks, occupying and resting in the
same spot once occupied by tie rock
from which they were made, which
will always partake Of the nature Of
tho elements contained in the bed
rock, though by chemical action new
elements may be generated in the pro-
cess OF decomposition.
By soils OF transport W. mean such
as have been moved tro,h other places
by action of water, winds or giucicrs.
Such soils are likely 10 he more varied
in their elements than soils Of subsi-
dcnce. One particular class of sui!s
OF transport, OF more recent origin.
nre what we call creek and river bot
toms-the level margins of such
streams formed by their overflow and
the breaking down of adjacent hills.
There is yet special soil of TRANSPORT,
as it were, outside Of the general line
OF soils of transport. We refer to
1trap soils" AS these arc the result
OF volcanic action, whose surfaces arc
generally formed by subsistence or the
action OF water after such action, they
may be termed soils OF upheavul or
special transport. They are, in certain
cases, spread on rocks Of different
characters from those from which they
are formed.
hen we use tho term soil, in an
agricultural sense, we refer to the
thin, outer or top layer Of the carth':,
crust already mentioned. or the
mineral part Of this, silica or sand is
most abundant. Alumina (clay) and
lilhc are generally next most abund-
ant. Other elements such as iron.
magncsia. potash, soda, chlorine, am
monia. phosphoric, sllph,lric and car
bonic ids, all or n pat arc found In
soils, AMI most important ofull huD,ux,
brown substance formed by the com
bination OF earth with dccomposcd
vegetable and animal matter il the
soil.
Unm"s is the most important factor
III the soil. In tact, without il there
is no soil. as it is that which receives
and retains all plant iood--supplvinn
it ~ The shape of daily rations to the
plant. XHmHS is sometimes STYLED the
body of lie soil; it may more appr =
priatrly he called the life of tho soil.
since through its agency alone the soil
imrarts lie to plants.
a few words as to the foregoing
clements. Silica generally constitutes
from toriy-!ivc to ninety per cent. of
all soils. In "a soluble form il is taken
up by plants and is Il most essential
element in the stalking principle of
oil lnt. Il