The Vermont watchman. [volume] (Montpelier, Vt.) 1883-1911, 1889-04-24
The general plan of the experiment
was as follows.

The general plan of the experiment
was as follows:
Land was in all cases selected which, in
the Judgment of its owner, was uniform in
quality, which had all been cultivated alike
and which had not been MANFRED for some
years. Only on such land could it be ex-
pected that one plot would give the same
Weld as another plot, similarly treated and
that a fertilizer would considerably increase
the yield. Over the whole experimental
field was broadcast liberal quantity of nj
trogenous matter ana potash salts-more
than sufficient for maximum crop. This
was essential in order that the yield should
be limited by the quantity of phosphoric
acid in the SOIL and not by either nitrogen or
potash. The field was then divided into
seven or more plots, which were designated
by letters A, b, G, etc, and on which the
different phosphates were applied.
The phosphates chosen for comparison
were. 0D Dissolved bone-black, containing
1858 per cent of phosphoric acid. (2) A
tinely-pulverized phosphate rock, from
Grand Cayman island in the Caribbean sea-
containing considerable iron and alumina,
with 1922 per cent of phosphoric acid. (3)
Thomas-slag, by-product of steel manutac-
ture, containing 1876 per cent of phosphoric
acid az Ground South Carolina rock,
containing 25.5 per cent of phosphoric acid.
| (5) Bolivian guano, a phosphate guano
| from the West indies furnished by the
Quinnipiac Company of New London, con-
tanning 17.2 per cent of phosphoric acid.
On the first plot a quantity of dissolved
bone-black was used, which it was believed
would insure fair yield and yet would not
| be in excess of the needs of full crop, but
rather slightly deficient. A single plot was
| given to each of the other phosphates, and
| they were used in such quantity that the
cost of each was just equal to the cost of the
| dissolved bone-black on the first plot Two
or more plots received no phosphate, and
thus served to show the natural capacity Of
the soil itself to supply phosphoric acid to
the cror.
AS summed up by the director, these con-
illusions are arrived at: The experiment
made by Mr.. Bartholomew with corn in
1887, the repetition of that experiment in
1888, his experiment with potatoes in 1888,
Mr. Yeomans experiment with corn in
1888, and perhaps Mr.. Platts experiment,
are the only ones which can fairly be re-
garded as contributions to the question of
the relative practical value of the phos-
pilates under experiment In Mr.. Barthol-
omew's experiment of 1887 Grand Cay
man phosphate and Thomas-slag pro-
duced as large crop of ears, more stover
and as large total crop as the same money
value of dissolved bone-black produced,
while ground South Carolina rock produced
less than half as much increase of crop over
land which had no phosphates. In 1888,
with no furJner auultlOn OF pnOSpnateS, the
plot which the season before had received
Grand Cayman phosphate gave three
times as much increase OF sound ears over
the no-phosphate plots as the plot
which had received dissolved bone black,
more than three times as much increase
of slower and more than three times as
much increase of total crop. The plot which
had received Thomas-slag gave a still larger
increase Of crop The plot which had ground
South Carolina rock the year before pro
duced in 1888 more than twice as much in
crease of ears and two and half times as
much increase of total crop as the dissolved
bone-black. These results are differently ex
pressed in the following statement of tota
yield OF ears and total crop for the two years
Plot Fertilizer Yield Of Ears. Total Crop
A-Dissolyed bone-black.. 1919 lbs ls4e lb
B-Grand Caymans phosphate hoo lbs 2lA lb
E-Ground South Carolina
Observation-Disclosures. lVo71albs 1875 lib
and F-No phosphate (average). s42 lbs 1893 ID
There was profit in dollars and cents il
the use of either dissolved bone-black or tn,
raw phosphates, Grand Cayman an,
Thomas-slag. But on this land, in thes,
two years, raw pbosphates paid better thai
superphosphates There was no loss, per
haps, in the use of South Carolina rock
These conclusions are confirmed by thu
following statement of yield per acre for tn,
, two years: