JttlV 1, 1902.] 1?HE TnOPlCAt AGRICULTURIST. 
THE PURCHASE OP ARTIFICIAL 
MANURE. 
The following is the first portion of a paper which 
appeared in the Journal of the Board oj Aririculture 
for March 1902 :— 
There are three substances, and only three, that 
are valued in artificial manures, namely, nitrogen, 
phosphates, and potash. According, therefore, to 
the greater or less quantity of one or other of these 
substances the value of the manure will rise or fall. 
Some manures contnin only one of these substances 
— for instance, nitrate of soda and sulphate of am- 
monia contain only nitrogen ; super-phosphate, pre- 
cipitated phosphate, and basic slag contain only 
phosphate ; and kainit, sulphate of potash, and 
muriate of potash contain only potash — while other 
manures hold two substances of value, as in the 
case of bones, which furnish both nitrogen and 
phosphates, or saltpetre (very seldom used, however, 
as a manure), which supplies both nitrogen and 
potash. Only one class of so-called artificial manure, 
nsmely, Peiuvian or other similar guano, contaiua 
an important amount of all three substances. 
NITROGEN. 
In price lists nitrogen is frequently expressed as 
ammonia. The relationship between the two subs- 
tances is, however, a very simple one, and need 
occasion no difficulty or uncertainty : 17 lb. of am- 
monia always contain exactly 14 lb. of nitrogen, or 
what is the same thing from the farraers's point of 
view, 14 lb. of nitrogen are the equivalent of 17 lb. 
of ammonia. If, therefore, a sample of, say ' corn 
manure ' is offered as containing 4 5 per cent, of 
ammonia, this is the same as faying that it con- 
tains 3'7 per cent, of nitrogen. Sometimes, though 
not often, the figure is made to look more attrac- 
tive by being stated as sulphate of ammonia ; but 
this also need cause no difficulty, if it be remem- 
bered that 661b. of this substance are equivalent to 
no more than 14 lb. of nitrogen and 17 lb. of ammo- 
nia. If, therefore, we take the above eximple, the 
figures mf an one and the same thing, whether they 
are stated as 3'7 per cent, of nitrogen, or 4.5 per 
cent, of ammonia, or 17 4 per cent of sulphate of 
ammonia. But a manure merchant who failed to 
effect many sales for a fertilizer of ever so high- 
Boundirg a name on a statement of I per cent, of 
nitrogen 1'2 par cent of ammonia might be more 
successful with a certain class of buyer if he entered 
the nitrogen as equal to 4 7 per cent, of sulphate 
of ammonia, and yet the figures all represent 
the same fact. Under the fertilizers and Feeding 
Stuffs Act, 1893, the invoice must contain the mini- 
mum guarantee of nitrogen, stated as such. 
PHOSPHATES. 
Phosphates or phosbhate of lime may also be en- 
tered in an ana'ysis or price list in several ways, 
but as a rule this ingredient is either stated as 
above or as phosphoric acid. In an invoice, how- 
ever, the statement must be made as soluble or in- 
soluble phosphates, as the case may be. 
The relationship between phosphates or phosphate 
of lime, whether soluble or insoluble, and phosphoric 
acid is quite as simple as that between nitrogen 
and ammonia : 142 lb. of phosphoric acid always 
form 3101b. of phosphate of lime, so that to con- 
vert the former into the latter one may multiply 
by 2-2 which, though giving an answer slightly above 
the truth, is quite accurate enough for all ordinary 
purposes. 
It, therefore, the analysis of a manure is returned 
as 12 per cent, of pho«phoiio acid, it is equivalent 
to saying that it contains fully 26 per cent, of 
phosphates. Similarly 30 per cent, of phosphates is 
equal to nearly 14 per cent, of phosphoric acid. 
POTASH. 
Potash usually exists in manures iu the two forms 
of sulphate of potash and muriate or chloride of 
potasl). It takes 9i'2 lb- o£ pure potash to form 174 2 
lb of sulphate of potash, wherea? the name amount 
of potash will form only U9-2 lb. of the muriate or 
chloride. In the former case, therefore," to convert 
cotash into terms of sulphate of potash 'we multiply 
by 1-8.5, whereas in the latter cafo we ninltiply 
by 1-58. If, therefore, an arjaiysis of, say, kainit is 
stated as 12-5 per cent, potash, that i.s equivalent 
to say that it holds over t?3 per cent, of sulphate of 
potash: while muriate of potash gu nantecd to con- 
tain .36 8 per cent, of potash is of about 90 per 
c?nt, purity. ^ 
Just as a buyer m-y sometimes be led into pur- 
chasing a manure through it^ nitrogen being expressed 
as sulphate of ammonia, so may the contents of 
potash be made to look more attractive by being stated 
as sulphate of potash. In an invoice, however the 
potash mu.st be elated as such. ' 
The rules for approximately conveiting the various 
terms into their equivalents may be thus summarised;— 
To convert Nitrrgen into terms of Ammonia multi- 
ply by 1-2. 
To convert Nitrogen into terms of Sulphate of Am- 
monia multiply by 4-7. 
To convert Phosphoric 4cid into terms of Phosphates 
multiply by 2'2. 
To convert Potash into terms of Sulphoric of Potash 
multiply by 185. 
To convert Potash into terms of Muriate of Potash 
multiply by 1-58. 
Nitrogen and phosphates, and, to a less extent, 
potash, vary in effectiveness, and therefore, in value 
according to their source or origin. Nitro-'en is 
never so effective as when in the form of nitrate of 
soda. [See ' Note added ' Ed.l It is not quite so 
active, and for some purposes not so valuable, when 
in the form of sulphate of ammonia, though under 
certain circumsttnces this somewhat slower action 
may be regarded as an advantage. Nitrogen in what 
is called the organic form is in its least active con- 
dition, though here again the rapidity and effective- 
ness of action vary greatly. Nitrogen is in the 
organic form in blood meal, fish meal, bones, shoddy 
etc., and yet, as a i=ource of plant food, blood meal ig' 
more active than these other substances. It is claimed 
as an advantage for slow-acting manures that they hst 
longer, which is true ; but one applies manures not 
to last, but to act. It is only where it is convenient 
to apply manure at somewhat long intervals, as in 
the treatment of orchards, that the more inert 
manures are worthy of much consider.'ition. 
As regards phosphatic mannrep, it may be said that 
while soluble phosphates are all alike active there is 
considerable difference in the value of insoluble phos- 
phates. The insoluble phosphate of bone meal, for 
instance, is less effective, and for most purposes 
less valuable, than the insoluble phosphate of basic 
slag, precipitated phosphate, or even dissolved bones 
Some of the insoluble phosphate of the last manure 
has once been soluble, and has ' reverted,' and such 
phosphate is not much less effective than soluble 
chosphate. But raw bones as a manure have been 
longer known to British farmers than other forms 
of phosphate, and for this reason their price has 
kept relatively high. 
[Note Added.] 
With regard to the statements above relative t" 
the superiority of nitrate of soda, as a source of 
nitrogen, to sulphate of ammonia, it must be re- 
membered that the conditions which obtain in tem- 
perate regions are referred to. Experiments in Bar- 
bados have shown that sulphate of ammonia produces 
better results in sugar-cane cultivation than nitrate 
of soda. Sulphate of ammonia is changed by nitri- 
ficition in the sjil, into nitrate of calcium. Nitri- 
fication is very active in tropical soils, and this 
fact, together with the liability to loss by leachincr 
in the case of nitrate of soda, mxy explain the 
superiority of sulphate of ammonia in certain tropical 
la.uas,— Agricultural ^'ellJS. *^ 
