The Middlebury register. [volume] (Middlebury, Vt.) 1850-1882, 1877-07-13
Agricultural Department.
CosprorED BY ALBERT CHAPMAN
THE PHOsPHATES.

W
found in combination with lime, form
ing phosphate of lime. And Just here
1t will be we'll to consider these several
forms Of phosphate, Phosphoric acid
unites with lime in three proportions,
viz: one part acid to three parts of
lime, called the t1icalcic phosphate;
one part acid to two parts of lime, called
the 6icalcic phosphate; and one part
acid to one part lime, called the mono
calcic phosphate. The tricalcic form
contains the "insoluble" phosphoric
acid; the bicalcic form, the s'reduced"
phosphoric acid; and the monocalcic
form, the "soluble" phosphoric acid.
These different forms have different
values as plant food, owing to the de-
gree of solubility and consequent avail
ability to the roots of the plant. BY
reference to the article, "Valuation of
Manures," in the May number, ii will
be seen that these values are CONNER
cially expressed at twelve and one-half
cents per pound for the soluable phos-
phoric acid; nine cents for the reduced;
and six for the insolublc. The trical-
cic or insoluble phosphate is soluble in
100000 parts Of water. 1t is therefore
probable that portion is available to
plants In this form.
The value Of phosphate manure
depends, therefore, not only on the per-
centage, but, also, on the form in which
the phosphoric acid contained in it
exists. And the aim of the manufacturer
should be to have the larger portion of
this ingredient in the soluble form, as
1t IL for the interest of the buyer to have
1t In condition to be readily taken up
by the plants.
The usual sources Of phosphate of
lime are bones, mineral phosphates and
guanos; in all of which, and in barn
yard manures, 1t is present mostly
In the insoluble form. But 1t should
be remarked here, that this so-called in
soluble phosphoric acid Is gradually
changed to the soluble and available
form, when applied to the soil, through
the agency of the carbonic acid of de-
composing organic matter. In the case
Of finely ground bones, for example, it
Ia estimated that about so per cent. of
its phosphoric acid Is used by the crop
the first year, rs per cont. the second,
Is per cent. the third, etc. For general
use, however, the soluble form Is the
most economical; unless the farmer has
an unlimited capital, those boughten
manures which contain this plant food
In an Immediately available form are
the only ones he can afford to purchase. |
a manure which only makes partial |
return the first year Is like an invest |
ment Of money making similarly slow |
returns,-safe, perhaps, but less profit |
able than that which makes quick |
return.
The most prolific source Of phosphate |
Of lime Is bones, land the country has
been secured, from the backdoor and |
swill-tub Of the humblest cot, to render
ing establishments, battle-felds, and |
the great western prairies, for supply |
Of the raw material" Bone fertilizers |
are found in the market in several
forms, ground bone being the simplest.
Freso, raw bones contain an average of |
22.60 per cent. of phosphoric acid, or
about 80 per cent. Of phosphate of lime,
and from to per cent. Of nitrogen.
Bone-black IL also largely used as sup
ply of phosphate of lime. It is the re-
fuse of the bone charcoal used in the re-
timing process at sugar refneries, and |
and contains from 80 to 81 per cent. of
phosphoric acid, the heterogeneous por-
ton having been driven off by the
burning.
must have fine mechanical condition. |
This is always obtained in we'll manu-
featured fertilizers. Bones have other
value than for manure, however, and
before being used for this are usu-
subjected TO steaming and reducing
process to remove the fat, etc., for other |
purposes. This also helps to render |
part Of the phosphoric acid soluble. |
The residue-and the same for bone
black--is treated with sulphuric acid in |
the proportion of 69 parts of the latter
10 100 parts of tricalcic phosphate con-
tained In the bone. These are the theo-
rctically proper proportions, but in
practice less sulphoric acid is used
about one-half-On account of the ex-
pense; which accounts for the fact that
only portion Of the phosphoric acid in
the fertilizer is found in the soluble
Iorm. The sulphuric acid unites with
portion of the lime Of the tricalcic phos-
phate, leaving the remainder in combi-
nation with the phosphoric acid, soluble
and readily available for plant food.
We shall speak hereafter of the home
manufacture of superphosphatcs. The
term superphosphate of lime means the
some chemically as monocalcic phos-
phate above described, but Is applied
Unfortunately to any fertilizer the
principal Of which in value is phosphor-
ic acid.
Bones, though at first the main source,
now furnish but little of the phosphoric
acid Of fertilizers, so great has been the
demand for phosphate manures. To
supply the deficiency tho vast beds Of
mineral phosphates, so called, prove to
dQn0atfC -ol,
The chief Of them are located in Central
Russia, Western Germany, Southern
France, Canada, South Carolina, and in
the Navassa, Sombrero, Jarvis and
Baker Islands. The Navassa and South
Carolina deposits are now the main
sources Of supply. 1t has been estimate
cd that four-iifhs of the superphos.
pilates manufactured in this country are
now produced from the two last named |
sources. The Navassa contains from so |
10 Sc per cent. of phosphoric acid, the |
South Carolina from "a TO ~ per cent. |
Though so rich In this ingredient, It Is |
all In the insoluble form, and owing,
also, to the extreme hardness of the |
substance II is manipulated with diff
Guilty. Though ever so fine, sulphuric |
acid acts but slowly upon it due to its |
hardness, and, also, TO the presence of
carbonates of lime, magnesia, alumina, |
and oxide of iron. Tho entire absence |
Of nitrogen and potash from this class |
Of superphosphates makes them of value |
chiefly to use In connection with barn.
yard or other manure containing these
Indispensable ingredients Of an effective
manure. Some superphosphates are
manufactured from the real mineral
DhOsDhatas Anatite Tho above heino
The mineral remains of the deposits of
sea birds, otc. The insoluble phosphoric
acid Of the superphosphate made from
Apatite is held by Prof. Goessmann to
possess little If any appreciable value
rock containing IT, though the soluble