The Vermont watchman. [volume] (Montpelier, Vt.) 1883-1911, 1886-04-28
An Experiment with Phosphate Rock.

color, was about as heavy as the same
bulk of plaster, and had an odor like
superphosphate, though milder. Some
of this | treated with sulphuric acid,
and that used beside Soluble Pacific
Guano on potatoes gave equally good
results. applied it raw on green
sward and under several different hoed
crops, but saw no effect whatever from
any of the raw applications. 1t is very
largely used as the basis of superphos-
pilates by nearly all manufacturers of
commercial fertilizers, but from my
very limited experience with it | con-
clude that its action when applied raw
is much too slow to be satisfactory.
o. MCFADDEN.
West Dresden, Maine.
The above note appears in the Man
chester On. H. Mirror and Farmer.
We reprint it because we wish to col
lect all the information we can on this
subject. The writer, Judge McFadden,
is man of intelligence and enterprise,
whom we are glad to welcome in the
field of agricultural experimentation.
We are rather surprised to learn that
he got as good results from his plain
homemade superphosphate as from the
Soluble Pacific Guano, the analyses of
which in the experiment station reports
show it to be complete fertilizer with
fair percentage of nitrogen and pot
ash, in addition to its phosphoric acid.
The fact that he did so indicates that
his soil is in too good order for reliable
experimentation as it must have been
able to supply from its own resources
the fertilizing material which was lack
ing in plain superphosphate.
On his other crops he says the re-
suits, when using the unacidified phos-
phate rock, were practically null. This
was perhaps what was to be expected
in using the ordinary ground phosphate
rock in small quantity in place of an
acidified and complete fertilizer. Even
when the phosphate rock is used in the
form of floats " (Which is probably
ten times finer than the ordinary ground
rock and this, too, in combination with
due proportion of nitrogen and pot
ash, we have found it quite slow to act
in dry season, like the early part of
the last, in comparison with an acidi-
fed fertilizer On greensward we have
never got satisfactory results, even from
acidified fertilizers sown on old sod,
though they help new seedlings wonder
fully when well narrowed in before SOW
ing the seed.
In making these experiments we must
always remember to compare equals
with equals, and not with unequals. A
plain superphosphate is not fairly COM
parable with complete fertilizer, nor
is undissolved phosphate rock fairly
comparable with that which has been
dissolved in acid, when the same guam
tity of each is applied in the same way.
We must have regard to all the condi-
tons in order to get correct answers
to the questions we put to the land.
When we put the question whether I'M
acidified (so-called " insoluble y phos-
phatic material can be advantageously
used as fertilizer, we must never forget
that it is much more slowly soluble,
and that consequently we must expect
only part of it to become available
the first season. But for this very
reason it may be expected to be much
more lasting in its effect than an acidi
fed phosphate, which costs more than
treble the money for the same weight
of phosphoric acid. The whole point
of this part of the question is whether
two hundred pounds of fine phosphate
rock (loats) which costs less than one
hundred pounds of plain acid phos-
phate, while it contains nearly four
times as much phosphoric acid, may
not be profitably used without expect
ing that more than third of it will be-
come available the first year, leaving
two-thirds to be taken by subsequent
crops This is the way we all do with
our stable manure, and there is much
reason to hope that by using an equal
moneys worth of floats in place of
plain acid phosphate we may get as
good results the first season, and still
have large quantity of phosphoric
acid left in the soil, which will become
available in subsequent seasons. Here
is where the profit comes in, and this
is what makes it worth while to get at
the facts. OF course, as long as fertil-
izer-makers can get well paid for acidi-
fled phosphates they are not going to
advise us to use them merely ground.
On the contrary, they will naturally do
all they can to discourage such expert
ments.
The Ben Davis Apple.
Our valued friend and correspondent.
! oc