Pocahontas star herald., 1915-11-05

The lessons on Soil aud Soil Fertility
VIII consist OF the followlng' ul or
| lEinh and Functions OF Soil. t2l How
Plants Feed and Grow. go Tillagc, go
! Drainage, tdl Organic Matter, t6l Crop
| Rotation, 90 Rarnyard Manure. tNl
| Commercial Fertilizers Extra proof
sheets for each lesson win be kept for
| thosc who may decide later to UNDER
take the course@-J. n. Miller, pirec-
tor Cooperative Extension Work.
!. Origin and Function Of Soil.
Soil is composed Of finely divided
rock particles. called inorganic mat.
ter, and finely divided decnylng vego.
table matter. II occurs In two layers
which are known as soil and subsoil
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 to 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 a 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 OF
the earth was once a molten mass
which solidifed 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 10 the soil and became a part OF
t. Upon the death OF the plant tho
roots and stem OF the plant became a
part Of the soil. The decay OF plants
| enriched the soil by Fastening the
| chemical processes as well as by re-
turning plant food which could he
used over again. As the forests de-
veloped and year after year the
leaves, twigs and dead trunks we're
returned to the SOIL the surface layer
became darker and looser and more
porous than that underneath
Geological Classification.
All soil does not now OCCUPY its
original position This fact gives rise
to two general classes, first the sedeu.
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-
emulation through the effects OF
wind ice, water, or gravity. The re-
sidual forms the most important class
| Of sCdentary 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-
sentinE a Heterogeneous mass Of ma
terial They have been subjected to
! teaching for long periods and large
part Of the soluble materials have
been washed out
All our river bottoms are made up
Of alluvial or water transported soils
A large portion Of southern and south
eastern Arkansas is made up of ma
rine soil, or what is commcLly known
as coastal plains land. The sediments
which are continually being carried
away by rivers are sooner or later de
posted in the sea.
Soil Particles.
Soil particles vary in size from
coarse gravel to the very finest par
ticles of clay. Between these are
coarse, fine and very fine sand parti.
cles and what is known as silt One
can easily recognize the coarse and
fine grained soils by rubbing a very
small amount between the fingers.
The finer soil is the more silt and
clay II contains, the more sticky II Is
when wet When a soil contains a
moderate amount Of each Of the sev.
eral grades Of sand, silt and clay It
usually works easily and Is called a
Joan. When II contains more sand Il
IS called a sandy loan, or more clay,
a clay loan. II it contains a large
amount OF clay it is called a clay soil
The condition Of the soil affecting
the ease with which It may be worked
is called tilth. By good tilth" is
meant friableness. BY poor tilth" is
meant a cloddy or compact condition.
Tilth depends largely upon the amount