Free trader-journal and Ottawa fair dealer. (Ottawa, Ill.) 1920-1927, 1922-07-29
SURVEY OF ILLINOIS
SOIL PROVING AN.
IMPORTANT TASK
MAPPING AND ANALYZlNG SAM.
PIES OF VARIOUS SOILS OF
STATE AN INTRICATE AN D
SCIENTIFIC UNDERTAKING.

The University Of Illinois soil sur.
vey work which has attracted wide In
terest. Is as Intricate and eXacting
as II is scientific and important" says
an official statement, today from the
university describing the work
"ln conducting the soil survey, the
county constitutes the unit OF work.
ing area" the statement said. "ln
order that the survey be thoroly trust.
worthy II Is necessary that careful,
well trained men be employed to do
the mapping. The work is prosecuted
TO the best advantage by working IN
parties OF from two to four. Only
such men are placed I'm charge of
these parties as are thoroly expert
enced I'm the work.
THE men must be able to keep
their location exactly and to recog.
nize the different soil types, with their
principle variations and limits, and
they must show these upon the maps
correctly. A definite system is EN-.
ployed in checking up this work. As
an illustration, one man will survey
and map strip 80 rods wide and
any convenient length, while his as.
sociate will work Independently on
another strip adjoining his area. and
II the work Is correctly done the soil
type boundaries will match up on the
line between the two strips.
Accurate Maps Needed.
IAN accurate base map for field use
is absolutely necessary for soil map.
ping The base maps are prepared
nr e.. hn nil
the official data of the original or
subsequent land survey being used
as basis in their construction. Each
surveyor Is provided with one of these
base maps, which he carries with him
in the field; and the soil type boun.
daries, together with the streams,
roads, railroads, canals, and town
sites are placed in their proper loca.
tons upon the map while the mapper
is on the area. Each section, or
square mile, is divided into 40 acre
plots on the map, and the surveyor
must inspect every 10 acres and de.
termine the type or types of soil
thereon. The different types are indi.
Gated on the map by different colors
"A small auger 40 inches long
forms for each man an invaluable
tool with which he can quickly secure
samples of the different strata for in.
specton An extension for making
the auger 80 inches long Is taken by
each party, so that any peculiarly o.
the deeper subsOil may be studied
Each man carries a compass to aid
in keeping directions. Distances along
road are measured by a speedometer
or by some other measuring device,
while distances in the field away from
the roads are determined by pacing
an art in which the men become eX-
pert by practice The soil boundaries
can thus be located with as high
degree of accuracy as can be indicated
by pencil on the scale OF ole inch
TO the mile
Samples Analysed.
after all the soil types of a county
have been located and mapped, sam
pies representative of the different,
types are collected for chemical an.
alysis. For this purpose usually three
strata are sampled namely. the sur
face 90 to 6 2-3 inches. the subsur-
face GO to 40 inches). These strata
correspond approximately. in the com.
mon kinds Of soil, to 100000 pounds
of dry soil an acre in the surface
layer. and to two times and three
times this quantity in the subsurface
of the subsoil, respectively. This, of
course, purely arbitrary division,
very useful in arriving at a knowl.
edge of the quantity and the distribu-
ton of plant food in the soil but II
should be noted that these strata do
not necessarily coincide with the nat
ural strata as they actually exist in
the soil, and which are referred to in
describing the soil types.
by this system of samplng there
is represented separately three zones
for plant feeding. The surface layer
includes at least as much soil as is
ordinarily turned with the pillow. This
is the part with which the farm man.
ure, limestone, posphate, or other
fertilizer applied in soil Improvement
is incorporated, and which must be |
depended upon in large part to furnish |
the necessary plant food for the pro-
duction of crops. rich subsoil has |
little or no value if it lies beneath a |
wornout surface, but if the fertility of |
the surface Is maintained at a high |
point, then the strong vigorous plants
will have power to secure more plant |
food from the subsurface and the sub
soil"
ADDITIONAL BRIEFS