Americus times-recorder. [volume] (Americus, Ga.) 1891-current, 1903-03-03
FROM THE
STATE CHEMIST
A Treatise on Agricultural
Chemistry.
THE VALUE OF PHosPHoRIc ACID

Az q Constituent of Plant Food 1t Is
Most Important-In Same Class with
Nitrogen and Potash-InterestIng to
Farmers.
Continuing the letters of the State
Chemist TO Georgia Farmers).
In letter No. 4, bulletin No. 3S.
alluded to the Importance of phospho-
ric acid as a constituent of plant food.
It is in the same class with nitrogen
and potash, they being the elements
found only in small quantity in most
cultivated soils, all the other elements
necessary to plant life being usually
present in profusion. Phosphoric
acid, then, must be added to the soil
if we expect large yields. The vari-
Gus sources of phosphoric acid, then,
are of interest.
Bones were the first and earliest
form in which phosphoric acid was
applied to the soil. Bones are a COM
bination of organic and inorganic
matter. The organic matter in bone
Gus matter; the inorganic matter IL
chiefly phosphate of lime. This dual
| composition of bone can be demon
strated very graphically by taking
| the leg bone of an animal and soak
| ing it for quite a while in weak mu-
Ratio acid. The acid will dissolve
away the phosphate of lime, which
| x<i1 toll 49,
| bone, and leave behind the glutinous
flexible animal matter of the bone
which will still retain the shape OF
! the original bone. You can now take
this soft organic matter and tie il
into a knot, without breaking It, This
soft animal matter of the bone is rich
in nitrogen, so that a bone fertilizer
| is double manure, both phosphate
and heterogeneous. Bones vary a good
deal in composition, according to the
nature and age of the animal; there
Is not so much phosphate in the bones
OF young animal as those of an ole
| one. Even in the same animal, the
hard thigh bones Of an OK, for in
stance, will contain more phosphate
OF lime than softer bones from othe1
| parts OF the animal Bones to be O
value should of course be ground, an(
the finer the grinding the better. 4
coarsely crushed or ground raw bone
which has not been treated to remov,
any of its original fatty matter, will
decay with comparative slowness IL
the soil, and consequently but littl
effect might be perceived from 1t
application the first season.
A good raw bone Will contain on al
average p per cent. phosphoric acit
and 4 per cent. of nitrogen. Such
bone is quite difficult to grind fine
and On its fneness depends In larg
measure its value as a fertilizer. Blu
by boiling and steaming, much of tn
fat is removed, which has no value a
a manure; some of the nitrogen /
also removed in the form Of glue an
gelatine by the boiling and steamin
process. This treatment however er
ables the bone to be ground niue
finer than the raw bone, and where tn
process has been carried out yer
thoroughly, as in the manufacture @
glue, the resulting ground bone ma
contain as high as 30 per cent. c
phosphoric acid, but the nitrogen /
this case will be reduced to less tina
2 per cent. Actual experiments hav
shown that all the phosphoric aci
from a finely ground steamed bon
may become available in one to tw
seasons in the soil, while that from
coarse ground raw bone would not BIZ
come fully available In three or fou
seasons.
The Mineral or Rock Phosphates.
If bones were the only source c