378 
THE TROPICAL AGRICULTURIST. [December r, 1887. 
THE STEANGB DIFFEEENOES IN THE ACTION 
OF INSOLUBLE PHOSPHATES 
EXPLAINED. 
The following extracts are the reports of thoroughly 
reliable scientific chemists, made by them after long 
laborious and exhaustive research. And strange to 
say most of the tests and experiments were for 
differ ent purposes and to prove entirely different 
views. And yet when taken together, grouped and 
classified, they all lead to one conclusion, namely, 
that phosphoric acid in conjunction with alumina 
is the most advantageous combination for plant 
food. 
First, in the published reports of the Agricultural 
Experiment Station of Virginia, published in Rich- 
mond in 1885, on page 11 we find the following 
remarks :— I could name many farmers in "Virginia 
who, having used phosphates both raw and reverted 
(in natural guano), have found them absolutely 
without effect. It chances that I have no report of 
anyone who has used acid phosphate without resulting 
benefit. In my own experiences, I have had striking 
results from the use of phosphatic guano and from 
acid phosphate mixed with kainit, but raw phosphate 
has done no manner of good on my land as far 
as I can discern. My land seems to lack the 
power of dissolving the so-called insoluble 
phosphate, (or of helping the plants to do so, 
which is probably nearer the correct theory) con- 
tained in the raw Charleston rock. On the con- 
trary, there are many soils on which it is found 
most beneficial and economical to apply the phos- 
phate in this shape, sometimes with the addition 
of potash, sometimes without. " Give it time, " say 
the able writers and farmers referred to, " and the 
insoluble phosphate will be brought into the con- 
dition of available." 
" Sow it in the spring upon your corn land ; it 
will increase the crop of corn, and by. the fall will 
be in just the condition to benefit the wheat, or 
to grow a crop of clover to be followed by wheat. 
Why spend your money for acid phosphate? You 
are buying and that too at an increased price, an 
additional 50 per cent of sulphuric acid and water 
which the land does not want — nay, which maDy 
hold to be positively injurious. Reflect that 400 pounds 
of raw phosphate contains as much phosphoric acid 
as 600 pounds of dissolved. 
The same authority quotes from the Journal cle 
I ' Agriculture, published in France, a statement 
made by M. Deherain, professor at the National 
School of Agriculture of Grignon, concerning experi- 
ments in the use of superphosphates continued 
during four years. He concludes " that superphosphates 
exercise no beneficial effect upon the soil of Grignon." 
"Why is this? Why do soils apparently very 
similar give such different results from the applic- 
ation of the same fertilizer ? 
On page 12 of the same work quoting still Deherain, 
he says ■ — " In calculating the effect to be produced 
by this fertilizer it is not sufficient to determine the 
total quantity of phosphoric acid contained in the 
soil ; we must go further and see with what basis 
the phosphoric acid is united. 
Again, "But in all probability there are in certain 
soils peculiarities which hinder the action of fertilizers ; 
or else the absence of some principle necessary to 
enable the acids of the soil or the peculiar acids of 
the plant to act upon the fertilizer and render it 
available. 
M. de la Morvonnais says that it has been found 
in Brittany that phosphates, particularly fossil phos- 
phates, do not act well on soils that have been recently 
limed. His theory is that lime neutralizes the acids 
of the soil necessary to dissolve the phosphates and 
eo hinders the action. 
Georgia report 1885 page 30 says :— " The use of floats 
was attended by actual money loss." 
It is generally understood that ground apatite, a 
crystallized phosphate of lime, is no better in the 
noil than so much sand ; and ground Charleston rock 
(another phdsphate of lime), in a very insoluble condi- 
tion alto dues but little good. 
These known facts demonstrate that insoluble phos- 
phate of lime has little or no effect as plant food. 
On the other hand, the Royal Agricultural Society's 
Journal, vol. 22, part 1st, pages 250 and 251, shows 
that insoluble phosphate of alumina gave better re- 
sults than dissolved phosphates, ground coprolites, or 
bone meal. 
Dr. Cook, of New Jersey, says in five cases out 
of eight " the yields of soluble phosphoric acid were 
surpassed by those from insoluble forms of phosphoric 
acid used under corresponding conditions." One of 
the abovementioned forms of insoluble phosphoric acid 
was phosphoral — an insoluble phosphate of alumina. 
Professor Dunkelberg of Bonn University, in his long 
report to the German ministry, claims that iron and 
alumina phosphates are more certain in their action, 
and altogether preferable to the phosphates soluble 
in water. 
Professor Maercker says in his summary of the 
results of a large number of experiments with different 
crops, on various soils, using different fertilizers, that 
in all instances but one the phosphate of alumina 
made a greater increase than any of the others. 
Hoff meister's paper says phosphate of alumina gave 
larger increase than any other, and argues that soluble 
phosphoric acid becomes phosphate of iron and alumina 
in the soil, because iron and alumina are always 
present there. 
Next, Stillwell & Gladding's experiments show that 
soluble phosphoric acid becomes immediately insoluble 
in the soil. Thenard and Deherain claim the same, 
and this point is now cenceded by all agricultural 
chemists- 
Also Hoffmeister's paper, page 813, states that 
phosphoric acid when applied to the soil in a soluble 
form always becomes reversed to alumina and iron 
bases, because iron and alumina are always present 
in the soil. 
And Muldner, in " Ohemie der Akerkrume," vol. I, 
page 485, claims that the use of alumina in the soil 
is to retain the phosphoric acid for the use of plants. 
Baron Von Liebig proved long ago that plants had 
the power to dissolve the phosphoric acid from its 
mineral salts by the aid of the acids contained in 
their roots. 
And again, Drs. Peterson and Voelcker say that 
it is demonstrated that plants do absorb the phos- 
phoric acid when in conjunction with alumina and iron. 
Therefore it follows that the insoluble phosphates 
of lime must be made into soluble phosphates, so 
that their phosphoric acid may be made into a con- 
dition to revert to the alumina, from which base 
the plant has the power to absorb it. 
There is, however, one class of phosphates of lime 
that do some good in an insoluble condition, because 
the phosphoric acid is in loose combinations, so much 
so that the action of the acids in the soil is suffi- 
cient to make it so soluble that it can change its 
base and revert to the alumina that is always present 
there. This class is what is called the natural phos- 
patic guanos of the West Indies, such as Mona, 
Orchilla, Aves, etc. 
The phosphates of alumina that have proved suc- 
cessful by experiments on the land are Redonda 
(tested by the Royal Agricultural Society) and Phos- 
phoral (tested by New Jersey Experimental Station), 
and lastly the Combination Natural Phosphatic Guano 
from the Cayman Islands, this is a phosphate of 
alumina, iron and lime, the phosphoric acid being 
lightly combined. This has been well tested in Vir- 
ginia and North Carolina by the Carib Guano Com- 
pany, of Baltimore, and in Long Island, New York 
and New Jersey by the Grand Caymans Phosphate 
Company, of Kingston, Jamaica, where great results 
have been obtained from the use of their guano 
when even only partially ground. 
In conclusion, therefore, it follows that phosphate of 
alumina in easy combination is the exact form to 
make the best plant food, whereas phosphate of lime 
must be made soluble that the phosphoric acid may 
revert to the alumina always present in the soil.— 
Causality.— Oil, Paint, and Drug Reporter. 
