The Anderson intelligencer. [volume] (Anderson Court House, S.C.) 1860-1914, 1881-02-24

4
Phosphoric acid. ....... g
Loss during analysis, &c. 5.4
100
Having already commented on the
functions of alumina and organic matter
in the soil, we proceed now to notice
other points.
Scarcely any TWO soils will show iden-
tity of composition; nor do we mean
to say that all fertile soils conform to the
standard above given. But d soil to be
fertile, must contain, not necessarily in
the same proportions, but to sufficient
extent and in available forms, all the
constituents given in our table. For all
pllols lake up from the soil, but in diff
fereI6 proportions. potash, soda, lime,
magnesia, oxide iron, oxide manganese
sometimes, silica, chlorine, sulphuric and
phosph, ic acids. Every soil, then, to
be productive, must contain all these
substances. Those constituents which
exist in the soil in small quantities are
exactly those which demand the special
notice and care Of the farmer. This is
so because they are most liable 10 ex-
haustion for the double reason: ~ Be-
cause they are found to so small an
extent in the soil, and (2), because upon
them the growing plant makes its heav-
lest uemunds. Let us look at this matter
a little more in detail. The amount of
phosphoric acid is given as 0.4 per cent.
or four-tcnths of pound in 100 pounds
dry soil, and very few soils contain even
so much as this: Is not this too small
an amount of phosphoric acid to arrest
serious attentions We reply by saying
that the amount of phosphoric acid ia
the soil is exceedingly small, but at the
same time enormously large. Relatively
small, absolutely large. The soil of an
acre II inches deep will weigh, in round
numbers, 100000 pounds, and will
contain at the rate Of for-.tenths, of q
pound of phosrhoric acid in 100 pounds
soil-0.4 per cent.-16,000 pounds or
tons of phosphoi,c acid. 10 add this
much phosphoric acid to the soil would
demand per acre little more than IL
tons of pure bone phosphate A soil,
then, containing no phosphoric acid, Is
agriculturally worthless. To attempt to
supply four-tenths of one per cent. Of
phosphoric acid to such soil would cost
more money than the value of Tie heav.
lest yield at the highest prices Of white
Burley tobacco in the limestone regions
of Kentucky. A soil containing no pot
ash, no soda, no chlorine, no lime, no
sulphuric acid, no phosphoric acid, all
of which added together make only (see
table, seven per cent. OF the weight of the
soil, is no soil at all it is simply des-
! ert.
But, as we have remarked, the plant
makes its heaviest demands on those
constituents of the soil, which constitute
such a small part of its weight. For
instance, the ash of the grain of wheat
| fol Df ,k1
in other words, wheat and the cereals
generally take up from the soil about as
much of phosphoric acid as of all the
other substances furnished by the soil
put together. So. also, more than half
the weigi Isl per cent Of the ash of
potatoes ia potash; nearly two-thirds (64
per cen..) 1t tobacco ash is made up of
potash and lime. We might continue
the illustration to any extent, showing
that plants make upon the soil the heav-
lest demands for those substances which
1T contains in the smallest proportions.
Hence the intelligent farmer seeks to
add these substances to The soil by the ap-
plication of various fertilizers, particular
ly commercial fertilizers; and sims. by
deep plowing and fallow crops, to hasten
the disintegfation of mineral masses, end
bring their soluble constituents to the
surface for admixture with the soil prop.
| er.
In the light of these facts, we see the
philosophy of rotation of crops. If q
soil be cultivated for succession of sea-
sons in the cereals, there will be an ex-
haustion, greater or less, of phosphoric
acid; and the constant cultivation of
tobacco on the same land will cause q
deficiency Of potash and lime in the soil.
Uhnf d. 81,
sort of crops rhould follow each other in
I0tfiti0nf %i,Jsc that make demands as
different rs possible upon the soil, 80
subjected &c special strain year after
year. For instance. tobacco will take up
potash and limo largely and very little
phosphoric acid. Let it be followed by
wheat, which will demand phosphoric
acid largely and very little potash and
lime. BY the time the land is again
planted in tobacco, the special exhaus-
tiOn of potash and lime caused by the
frat tobacco crop has been repaired By
the disintegration Of the purely mineral
matter of the soil, or by the addition of
lime and potash in the form of manure.
or as is usually the case, by the combina.
tion of these processes.
We see also why soil, if let alone.
i always reverts to its natural condition.
Let us consider two areas: One naiu-
rally poor, has been so fertilized that it
produces five barrels of corn to the acre !;
the other, naturally rich, has been so
exhausted by constant cultivation, that,
though once producing ten, it also now
produces only FIVE barrels. The produc-
tive capacity Of each is now the same
are the two tracts of equal value? BY
no means. The tract originally poor, If
let alone, will fall back to its original
barrennesS; the tract, naturally rich, if
let alone, will regain its original fertility.
The former has to be constantly nursed
and doctored that it may hold its own the
latter, without assistance except from the
recuperating powers of nature, will
become rich again. Why so? A soil is
only disintegrated rock mixed with vari-
able amounts of organic matter. This
rock underlying the soil is always break
lug down. It Is reduced by the plow, by
the roots ofplants, by the solvent power
ofwater, by the disruptive effect of'freez-
ing water, by alterations of heat and
cold, and by the chemical action of the
atmosphere. The composition of the soil