APRII. 1, 11^98. 
726 Snpplmmt to the Tropical AgricuUuHsV' 
THE VALUE OP BONE-DUST AS A 
FEKTILIZER. 
( Communic-’ted. ) 
We have onl^ ju^t seen an article in the 
New South "Wales Agricultural Gazette on 
the above subject, ret'ening to certain ex- 
periments, the results of whicli sliould prove of 
interest to planters in this Colony who largely 
use bone-dust as a fertilizer. 
In 1889 Professor Wagner of Darmstadt car- 
ried out a series of experiments wl)ich led to 
the surprising conclusion that the phosphoric 
acid in the oidinaty raw bone-meal was so 
low in fertilizing value when compared witli the 
phosphoricacid in superphosphate or Thomas slag 
as to be almost worthless. The estimated low 
value of bone-meal was based, it is said, not 
only upon its immediate effects but also on its 
after-effects. We need not refer at length to 
the details of Wagner’s experiments, sutRce it 
to say that equal quantities of bone-meal super- 
phosphate and basic slag were used, and all 
other conditions were the same, but the results 
as regards both the immediate and after-effects 
of the bone-meal were so inadequate os to lead 
Wagner to put it down as practically worthless 
for its phosphoric acid. As a result of these ev- 
periments the Association of Bone-meal Maiu^ 
facturers of Saxony appealed to Professor Marcher, 
of Ilalle, to investigate the question thoroughly. 
Miircker’s experiments extended over 4 years (us 
against 3 of Wagner’s) and embraced different kinds 
of crops and soils, and different brands of bone- 
dust, (raw, steamed and degelatinized,) repre- 
senting the best qualities of bone-meal on the 
market. Prof. Wagner would appear to consider 
that the phosphoric in raw bone-meal, in steamed 
and glue-free bone-meal is about equal in value- 
Where equal quantities of bone-meal and super- 
phosphate were used, the results of the trial for 
early effect were as was to be expected, very 
unfavourable to bone-meal. As a result of a 
variation of the same experiment it was found 
that there is no advantage in mixing bone-dust 
witli superphosphate, ns the increase of yield is 
practically due only to the superphosphate. The 
soils in these experiments were sandy ones which 
are .regarded a.- lieing particularly benefited by the 
appliciiiion of bone-dust. The next series of ex- 
periments were conducted to lest the fact wheth.er 
bone-meal is really valuable for its after-effects, 
and, if, as it is reported to do, it permanently 
enriches the land. 
With small (piantitii'S of supeiphosphate there 
were no striking results in the .second year, as 
the greater ']).irt of the available phosphoric 
acid hud already I'cen used uj) in tlie first year. 
AVhere a larger quantity of superphosphate (but 
equal to the amount of bone-meal) was used, 
the after-effects were con.siderable, and though 
not as good as in the first year, were, never- 
theless, very much better than the after- 
effects of bone-meal. During the third year, the 
after-effects of bone-meal as com])ared with su]ter- 
pho.'-phate, were found to be still less favourable. 
Another .series of experiments went to show 
that the after-effects of bone-meal are not increased 
when used in conjunction with superphosphate. 
The result.s of the experinnnts above quoted would 
appear to warrant one conclusion, viz., that, at 
all events, for sandy soils, wdiich are exactly the 
.'oil- .'Upposed to he benefited by bone-dust, the 
action of the phosphoric acid in bone dust does not 
approach the action of the soluble phosphoricacid 
in superphosphate, whether the bone-dust is used 
alone or with suprerphosphate, whether in resptect 
to the immediate results or after-effects. 
The next series of experiments were undertaken 
on different classes of soils, relatively rich in 
prhosphoric acid, having been used in previous 
years for bone-meal experiments. The soils 
included sandy soil.«, loam, humous loam, clay 
loam, sandy loam, humous sand, &c. The 
results were again unfavourable to bone-meal 
manure. The.se experiments, as Prof. Miircker 
observes, would have an unwelcome result if it 
were not possible to treat bone-meal in a cheap) way 
so as to make it more effective, and this can be done 
by means of a small quantity of sulphuric acid 
not enough to produce superphosphate but bi- 
calcium phosphate, a form which, tliough insolu- 
ble in water, is ready available to the p)lant and 
little inferior in fertilizing value tosuperphosphate. 
This can be done by adding to every 100 lbs. of 
raw bone-meal, 20 lbs. of acid of 60 ® strength 
(Baume) or 40 lbs. to every 100 of glue-free bone- 
dust. It is advisable that the bones should not be 
in too fine a powder, but in a coarse state about 
the size of peas. The proportions given are said 
to be the most effective. 
To quote Prof. Miircker’s own words : “ One may 
twist and turn the matter as one will, whether 
used with cereals or crucifers, in sand, clay, or 
loams, rich or poor in pho.sphoric acid, in cold or 
hot years, whether in respect to its effects upon 
the first or upjon succeeding crops, the result is 
always the same, namely, the action of the phos- 
phoric acid in bone-meal, whether raw or steamed, 
or glue-free, is invariably unsatisfactory, and the 
author comes to the conclusion that it is high 
time that raw, steamed and glue-free bone-dusts 
ceased to be regarded as phosphoric fertilizers ; 
they require previous treatment justas the mineral 
phosphates do, in order to make effective fertili- 
zers of tliem, and the author believes that the 
future of the bone-meal industry lies in the 
preparation of these products which the experi- 
ments here recorded liave shown to be effecti\e.” 
'The inference to be drawn from these experi- 
ments is that the besieficial action of bone-meil— 
for that it is beneficial cannot be gainsaid — is due 
not to the phosphoric acid but to the nitrogen it 
contains. ITof. Miircker is reported to be — at the 
date of the article here summarized — engaged in a 
series of experiments, with the object of ascertain- 
ing more exactly the nature of this action. As 
far as he has gone trials have shown that the effect 
of the nitrogen in bone-meal is 70 to 80 per cent 
of that produced by nitrate of soda in sandy soil, 
and from -5o to 70 per cent in humus loam. It is 
said that an independent series of experiments 
carried out by Dr. Liechti and Dr. V’oght of the 
University of Beinin 1896, goes to substantiate the 
results of Wagner and Marcker. In the-'e trials 
it came out that the effects of Thomas phosphate 
were far superior to those of raw as well as 
degelatinized bone-meal. 
A question that suggests itself to our mind is, 
to what extent is hone-dust affected, i.e., rendered 
