St. Landry democrat. (Opelousas, La.) 1878-1894, 1888-11-17
CHEMICAL. ANALYSIS.
Its Unreliability When Applied to the e
amiftatson Cf SniI,


amitatiob Of scil
It is often thought that d chemica
examination of any soil will reveal tn
true value of the ingredients contained
in it. Many, consequently, have tn
idea that to analyze the soil chemical,
is sufficient to show what elements ar,
present and how much of these ele
ments can be utilized by the plant il
the process of its growth. And further
that by knowing the mineral cOnstit
uents of the matured plant and the tota
amount of these constituents extracted
BY the crop, it will be an easy step t.
ascertain what mineral fertilizers are
needed to apply to the soil to make uE
any deficiency caused by their absence
from the soil, or to make good what is
extracted by the crop.
Director II. B. Battle, of the N. c..
Z. S., says that the fallacy of this rea.
soning lies in the fact that q chemical
examination Of the soil, while it does
give the total quantity of its constitll.
ents, does not give the quantity avail
able to the plant, such as can be
utilized by the plant. This fact is all
important, foe there may be plant food
in abundance in the soil, yet in such
a form that 1t is impossible for the
plant to derive any benefit from it's
presence, though 1t may lie in intimate
contact with its numerous roots. Many
Of our ordinary teldspathic rocks con-
tain in every 100 pounds as many as 10
pounds Of potash. Yet these 10 pounds
almost equivalent to 100 pounds of
kainit-are in such an insoluble, I'M
available form, that they are absolute
ly unserviceable as plant food, unless
by some process of disintegration and
decomposition, they may become
changed to form which the plant can
take up.
The thorough chemical examination
will give the quantity of potash pres
ent, and likewise the quantity of the
other chemical elements, but the sci
ence of chemistry has not yet devised
an exact method for determining the
proportion of these constituents, which
is available to the needs of the plant.
and which can be used by it in its
growth.
But does chemical analysis of the
soil, no matter with what exactness it
is carried out, show with sufficient &C
curacy the contents of the soil? Can
we depend on its results to show with
definiteness what fertilizer to apply to
the soil to render it more productive2
For this distinct purpose the chemical
analysis, always so delicate and accu-
rate, is inadequate. A cubic foot OF
our average upland soil (from results
obtained at the station in the |
pasO, weighs 40 pounds. An
acre of this soil, 9 inches deep,
weighs 2,S35,062 pounds, or a
traction over 1,417 tons. Nine inches
are taken as an average depth reached
by plants roots; with cotton the tap
'oot grows even much lower than this.
The ordinary application of ammoni-
ated fertilizer is 200 to 800 pounds to
he acre. If this application of 800
pounds is Thoroughly mixed with the
'oil, and an average sample obtained,
hen by no chemical means, no matter
low delicate, can this ammoniated fer
1lizer be detected, and yet this appli-
alton changes the yield from an I'M
to a productive one, and
[raws the line between success and
allure. Not only can not 800 pounds
o the acre be detected by chemical
means, but it is also the case with 500
ounds, with 1000 pounds, with one
On, to the acre. We can see, there
ore, how little we can expect from a
hemical analysis of soil.-Rurai
'esg Yorker.