Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1880-07-21
Z" soIublen and "InsoIuble ~ Phosphates.

"Soluble" and "Insoiuble - PhOsphates.
The question of cheaper fertilizers is one
of such Importance that we do not hesitate
to give to it all the space necessary for its
full discussion. The great price of highly
manufactured phosphates and the low cost
of manufactured phosphate materials
make it important that the question how
much manufacturing is really necessary and
profitable with phosphate manures should be
settled. If simple fine grinding is sufficient,
or if, where quick fertilizer is wanted, the
cheaper two-lime phosphate is really better
than the high cost one-lime variety, then the
problem of cheaper fertilizers is solved in a
satisfactory manner. DIR. Augustus Voelcker
of England, skillful agricultural chemist,
states the questions at issue plainly in the
following extract from an article from his
pen in the Journal Of the Royal Agricultural
Society.
Briefly stated, the following are my views on
the comparative efficacy of different kinds OF
phosphate materials and the economy of applying
them to the land, either in raw state or after
treatment with acid ~ Acid or soluble phos-
phate is not usefully taken up as such by plants,
and has to become insoluble in the soil before 1t
can become plant food. (2) The efficacy of insol-
ube phosphate Of lime rs a fertilizing ingredient
rises or falls with the more or less finely divided
state in which 1t occurs in various phospatc ma
terias. (3) The finer the state of division of the
particles of phosphate of lime in phosphate ma
terias, the readily it is soluble in water and
the more eilcacious are the phosphate materials
as manure. Therefore coarsely-ground coproites
and other phosphate minerals are less soluble
and less eflcacous than in a state of fine powder.
(l In porous soft bones the phosphate of lime oc-
ours In a different state Of aggregation than in
hard bones and in the former condition phosphate
is more soluble and etlicacious than in the latter
and for the same reason the phosphate of lime in
fine bone dust is more soluble in water and more
eficacious than the phosphate of lime in haf-inch
bones or coarse bone-dust. (5) In the form of
hard crystalline phosphate of lime, mineral phos-
phates-such as Norwegian, Canadian, and SPAN
ish apatite-are less soluble than in the shape of
porous phosphate materials, such as certain kinds
OF phosphate guano and semi-fossized rock
guano, for the simple reason that the particles of
phosphate of lime more finely divided and in
every case more soluble in water in the porous
materials, than in crystalline hard materials.
So far Professor Voelcker agrees entirely
with what we have said in our previous ar
ticles on this subject. lie then goes on to
state the case in favor of the use of the
highly soluble one-lime phosphate thus
"By treatment with acid, the phosphate of
lime in phosphate materials is rendered per-
fectly soluble in water, and on the applica-
tion of dissolved phosphate materials (su-
perphosphate) to the soil, the soluble phos
phate contained in the superphosphate is
precipitated and rendered insoluble by con-
tact with the soil. In this precipitated con-
dition, insoluble phosphate of lime is infin-
itely more finely divided, and in consequence
greatly more effcacious, than in the finest
state in which the raw materials used by
makers of superphosphate can be obtained
ing ain my judgment, chemical treatment
with acid is the most economical and best
plan of utilizing mineral phosphates for ag-
ricultural purposes"
1t will be observed that in the first extract
given he admits that "a highly acid phos-
phate is not usefully taken up by plants, and
has to become insoluble " Chat u.s. in pure
water, but not in the soil water) "before it
can become plant food" Therefore it is
plain that the superior value of a perfectly
soluble phosphate resides not in its useful
ness as plant food, but only in its superior
diffusibility through the soil in its soluble
state before it "reverts " to the two-lime
form. Professor Voelcker says that on this
account highly manufactured phosphate is
tl,, Of - Ia
state in which the raw materials can be OBJ
tanned by mechanical means" This is
doubtless quite true as regards immediate
results. Where the best and promptest eff
fects from a given quantity of phosphoric
acid is desired, a smaller amount of perfectly
soluble (one-lime) phosphate, il distributed
evenly over the land, will give the greatest
immediate effect. But here arise a number
of objections in the mind of the practical
farmer. The less the quantity applied the
more difficult it is to distribute it evenly, SO
that every plant, say in a wheat or turnip
field, shall get its share. Then, when this
costly high manufactured phosphate is used
in this way, it is all taken up by the first
crop. Nothing, if the end aimed at is fully
attained, will be left in the land from that
application. All will have been taken up
by the crop. One will say, that is just
what we want we do not wish to manure
for years ahead, this losing the interest on
the cost of the slowly available fertilizer
This is true reasoning on some crops, pro-
vided the excess in first cost is not greater
than the loss of interest. But when high
manufacturing doubles the cost of given
quantity of phosphoric acid we eau better
afford to buy twice as much for the same
money and wait two or three years for the
less soluble portions to become available
And in many cases we desire thus to ma
nure ahead. Especially is this true upor
grass farms. When we take up an ole
meadow for tillage we desire to get goot
crops in our rotation previous to reseeding
no doubt, but we do not wish to leave thu
new grass with no supply, or an insufficient
supply, of plant food for the ensuing years
We really want 10 leave it in as good hear
as possible. Therefore it is far better tt
use a cheap, slow fertilizer in large quantity
on the crops of the tillage than to put on
high cost quick fertilizer that will all b.
taken by the tillage crops. Or, in othe
words, it is better to put on to our corn, pc
tatoes and small grain in the usual rotation
five tons OF slow fertilizer made of fin
ground bone or phosphate rock and ashes o
potash salts than one ton of soluble fertil
izer Cat the same cost that is quick, blu
contains only fifth as much plant food
We get quite as good results with our tillag
crops, and yet have rich store left benin
for the grass. Here, in our judgment, il
where the profit comes in
A Quick Crop ON a Late Grass Seeding
4. A. 7. of Lower Cabot writes as follows
4. r L