The Nevada County picayune. (Prescott, Ark.) 190?-current, 1915-11-05
|. Oriqin and Function of Soil.


!. Origin ana Function of Soil
Soil is composed of finely divd ed
rock particles, called inorganic mat
ter, ard finely divided decaying vege
table matter 1t occurs in two layers
which are known as soil and sub-soil
The soil or surface layer contains
more decaying animal and vegetable
matter, and for that reason is darker
and coarser in texture.
In the course of time the finer parti
cles have washed down into the sub.
soil and have caused the layer II be
come tighter and heavier The sur
face soil furnishes the physical sup.
port for plants and the major portion
Of their plant food supply. The sub
soil provides storage place for mois
ture and furnishes some food for those
plants which are able to send their
roots into it,
Soils have their origin from rocks
Geology tells us that the surface oil
the earth was once a molten mass
which solicited to form rock Gradual.
ly the rock was broken to pieces by
various chemical and physical agen-
cies. With alternate heating and cool
ing the resultant expansion and con
traction caused assures to develop
Water getting into assures and freez.
ing caused further division. Water
running over rocks ground them down.
Wind carried the covering from rocks
and exposed them anew. The gases OF
the atmosphere produced chemical
changes which led to the breaking
down OF rock.
After rocks were broken down to
form soil, the development of plant
growth led to the introduction of or
ganic matter The leaves of plants
fell to the soil and became part of
1t. Upon the death of the plant the
roots and stem Of tho plat became q
part of the soil The decay of plants
enriched the soil by Fastening the
chemical processes as we'll as by re-
turning plant food which could be
used over again. As IN forests de-
veloped and year after year the
leaves. twiSs and dead trunks were
returned to the soil, the surface layer
became darker and loosar and more
porous than that underneath.
Geological Classification.
All soil does not now occupy it's
original position. This fact gives rise
to two general classes, first the seden-
tary or those soils which have not
been moved far from their point of
origin, and second the transported
soils which have been formed by ac-
cumulation through the effects of
wind. ice, water, or gravity. The re-
sidual forms the most important class
of sedentary soils in Arkansas This
is the main type in the western and
northwestern parts of the state. The
residual soils having been formed
practically in their present position
are old soils. without strata, and pre-
senting Heterogeneous mass of ma
terial. They have been subjected 70
teaching for long periods, and a large
part of the soluble materials have
been washed out.
All our river bottoms arc made up
of alluvial or water transported soils
A large portion of southern and south
eastern Arkansas is made up of MAJ
rine soil, or what is commonly known
as coastal plains land The sediments
which are continually being carried
away by rivers are sooner or later IL
posted in the sea.
Soil Particles.
Soil particles vary in size from
coarse gravel to the vary fncGt D2--
tlcles OF clay Between these arc
coarse, fine and very fine sand parti-
Giles and what is known as SIT One
can easily recognize the coarse and
fine grained soils by rubbing very
small amount between the fingers.
The finer q soil Is the more silt and
clay it contains. the more sticky II IA
when wet When a soil contains a
moderate amount of each Of tn sev.
eral grades OF sand, silt and clay il
usually works easily and Is called a
'oam When it contains more sand il
is called a sandy loan, or more cla,-.
clay loan. If it contains larg
amount of clay it is called clay soil
The condition of the soil afTect.n1
he ease with which it may be worlte,
Is called filth. BY good filth" l.,
meant friableness. BY poor filth" /.
meant a oloddy or compact condition
filth depends largely upon the amount
II humus or vegeta Die matter roi'
contains and upon the water contea.
Of the soil 1t the time Of working.