Peruvian Guano. 
187 
of ammonia: .The phosphates which guano contains — hone- 
earth in a finely divided state to the extent of 22 to 24 per 
cent. — as well as its soluble alkaline phosphates, are presented in 
a very valuable shape. Its alkalies, specially the potash, will 
much benefit crops on light soils, which are generally deficient 
in this element. 
As long as Peruvian guano was sold at a price which left a 
broad margin for profit, many farmers did not trouble themselves 
to enquire whether they derived the utmost advantage from its 
application, or whether they did not incur a partial waste by 
applying it to crops or upon soils for which other fertilisers were 
better suited. But a gradual rise in price compelled them to study 
greater economy in its use, and to try experiments with a view 
of ascertaining when, and in what quantities, for what crops, and 
upon what soils, it should be used. 
The successful employment of superphosphate and similar 
artificial manures, prepared more particularly for root-crops, has 
at the same time very much tended to enlarge our experience 
and knowledge on the relative merits of phosphatic and ammo- 
niacal fertilisers. The high price of guano for the moment 
aided the introduction of superphosphate, and gave greater range 
and precision to this branch of agricultural science. 
The true interests of the importers of guano and the manu- 
facturers of manures are not opposed to each other ; for Peruvian 
guano, judiciously used for special purposes, can well compete 
with other artificial manures ; and for other purposes a much 
cheaper manure may often be used with greater advantage in 
preference to guano. 
It appears desirable that Peruvian guano, as hitherto, should 
be sold genuine by the recognised agents of the sole importers ; 
and the supervision which the importers exercise in appointing 
respectable agents, and the care they take to prevent the adul- 
teration of guano, deserve all praise. If, however, it can be shown 
that the efficacy of Peruvian guano may be greatly increased by 
certain chemical and mechanical means, requiring more time and 
attention than the farmer is likely to bestow upon it ; and that the 
admixture of other fertilising matters renders guano more useful 
in many cases, it must surely be an advantage to the importers 
to give fitting opportunity for its being so treated and combined. 
If it were true that the proportion of nitrogen in the organic 
matters and of ammoniacal salts in manures solely determined 
their efficacy and value, in reference to all crops, in all climates, 
and on every description of soil, Peruvian guano, perhaps, would 
be pre-eminently the most valuable artificial manure. We know, 
however, very well that this large supply of nitrogen is, in some 
cases, of no use whatever, and in others exercises a decidedly in- 
