The Grenada gazette. (Grenada, Miss.) 1885-18??, 1888-11-22
CHEMICAL ANALYSIS.
Its Unreliabrity When Applied ts The IA
animation Of Soil.

As sVhctiubi'ty "h'h "pfsN -
animation Of Soil.
II is often thought that a chemical
examination Of any soil will reveal the
true value OF the ingredients contained
in il. Many, consequently, have the
idea that to analyze the soil chemically
i. sufficient to show what elements are
present and how much Of these ele-
ments can De utilized by the plant in
the process Of its growth. And further,
that by knowing the mineral constit-
uents Of the matured plant and the total
amount of these constituents extracted
by the crop, 1t will be an easy step to
ascertain what mineral fertilizers are
needed to apply to the soil to make up
any deficiency caused by their absence
from the soil, or to make good what's
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 a chemical
examination of the soil, while it does
give the total quantity Of its constitu.
ents, does not give the quantity avail
able to the plant, such as can be
utilized by the plant. This fact is all
important, for 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 its
presence, though it may lie in intimate
contact with its numerous roots. Many
of IL 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 unserviccable as plant food, unless
by some process Of disintegration and
decomposition, they may become
changed to a 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
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 a chemical analysis OF tho
soil, no matter with what exactness it
Is carried out, show with sufficient ac-
curacy the contents of the soilp Can
depend on its results to show with
aeiniteness what fertilizer to apply to
the soil to render it more productive?
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
past), weighs 10 pounds, An
acre Of this soil, 9 inches deep,
2,S35,06 pounds, or a
over l.4l7 tons. Nine inches
are taken as an average dept reached
by plants roots; with cotton the tap
root grows ever much lower than this.
The ordinary application of ammoni-
lted fertilizer is 200 to 800 pounds to
the acre. II this application of 900
IS euorUugly mixed with the
soil, and an average sample obtained,
then by no chemical means, no matter
now delicate, can this ammoniated fer
.ilizer be detected, and yet this appli-
cation changes the yield from an un-
productive to a productive one, and
1raws the line between success and
Not only can not 800 pounds
the acre be detected by chemical
means, but it is also the case with 500
pounds, with 1000 pounds, with one
.on, to the acre.. We can see, there
lore, how little we can expect from a
chemical analysis Of a soil. Rural
NeW Yorker.