Guano is the excrement of birds feeding on fish
in almost rainless zones, deposited on desert
islands in the course of thousands of years. In
the same year nitrate of soda and other portable
manure was also imported from South America.
Chemists analysed guano, and found it richer in
ammonia, the principal element in fertilising
corn crops, than any other known substance.
But, although farmers had not then reached
their present state of confidence in chemists,
they were rapidly converted, in spite of the
patriotic speeches of haters of innovation, by
the sight of great crops grown with the help of
guano by the side of poor crops grown without.

In 1839, Professor Liebig had suggested the
application of sulphuric acid to bones for the
purpose of producing "super-phosphate of lime,"
the leading element in root crops. His suggestion
was first applied on a commercial scale by
a young Hertfordshire squire, whose favourite
pursuit had been chemistry even when an
undergraduate at Oxford. His agricultural
connexions and position, as one of the council
of the Royal Agricultural Society, brought into
notice "Lawe's super-phosphate" as a portable
manure which crops could absorb more quickly
than even bone-dust. Super-phosphate of lime
supplied a want long felt by the root-grower of
a portable manure which could be applied when
and where required to fertilise the plant at a
critical time, and push forward its leaves beyond
chance of injury from the "destructive fly."
Stimulated by the steady demand, bones were
imported from every country in the world,
especially from the plains of South America, where
at that time beasts were slaughtered for their
hides and tallow only. Next, the geologist came
to the assistance of the agricultural chemists,
and fossils, coprolites, and appatite were found,
when ground and submitted to the action of
sulphuric acid, to yield a less soluble but still
useful phosphate of lime.

The introduction of these two eminently
portable manures, the one ammoniacal, the other
phosphatic, producing evident and extraordinary
effects, created a new class of manufacturers, who,
by the manipulation of bones, flesh, blood, and
other waste material containing nitrogen and
the phosphates, with an admixture of guano,
produced ammoniacal and phosphatic manures
of more or less value for each description of crop,
corn, roots, clover, beans or grass. Amongst
these manufacturers were many able and honest
men, who maintain their position to this day.
But there were also a crowd of impostors, who
palmed upon the credulous farmers, at an
apparently low price, worthless stuff bearing in
colour and smell a very close resemblance to
really valuable manures. And it was in this
way that farmers first began to consult the
chemist, and place confidence in the inquiries of
science. What farmers had to learn is very
neatly explained in the following passage from
Gibson's Hand Book of Agricultural Chemistry:
"In applying manures, we not only put back
into the soil the fertility that has been taken
away in crops, but we add new material, and
by altering its constitution add to its
productiveness. It often happens that, soils possessing
most of the character of fertility are defective
in one or two essential constituents; by adding
these, the quality of the land is greatly
improved. Few soils are equally fitted to grow
every kind of crop. For instance, clay soils,
which will produce five crops of corn with
little or no manure, do not yield the best
crops of turnips. Turnips will flourish where
corn fails, while lime soils are particularly
favourable to clover, pease, and other
leguminous plants. A complete soil, on the
contrary, will produce with almost equal luxuriance
every kind of crop."

In theory, any soil may be rendered perfect
and complete; in practice, the improvement
must be limited by the cost, especially of carriage.
It would require on some soils forty shillings of
special manure to grow twenty shillings of
produce.

In the transition stage of British agriculture,
say between 1844 and 1855, there was an
axiom, which, from the mouth of a squire
of the old school, addressing, say, a party
of Northamptonshire farmers, never failed to
bring down repeated rounds of applause:
"Nothing like muck." Of course this axiom
was accompanied by contemptuous reference to
guano and other foreign rubbish. It was
reserved for the chemists to show the true value,
the true mode of manufacturing, preserving,
and applying the invaluable home-made manure.
If the Royal Agricultural Society had done
nothing else than give the world the benefit of
the experiments of their chemists, Professors
Way and Voelcker, the vast cost of its maintenance
would have been amply repaid.

Dr. Voelcker states broadly that no amount
of artificial manure, however skilfully mixed
and prepared, can ever imitate or supersede the
use of farm-yard dung. But artificial manures
will often supply, within the short time required
for starting and maturing a crop, a want which
no quantity of farm-yard manure could supply in
the time. For example, the essential of a good
corn crop is ammonia or nitrogen, of a root
crop phosphate of lime; both these constituents
are found in well-rotted farm-yard manure. But
to get one pound of ammonia we must take
one hundred and thirty-seven pounds, and to
get a pound of phosphate of lime one hundred
pounds of well-made dung, while we can get
both in about twenty pounds of artificial
manure. What are called exhaustive crops are
those which draw the greater part of their
nutriment from the surface—for instance, flax; but
the chemist has taught the farmer that after a
crop of flax an excellent crop of wheat may be
grown by a top dressing of guano, which
supports and stimulates the young wheat crop
until it has had time to send down its rootlets,
and drink up the ample stores of fertility available
in well-cultivated soil.

The advantages, then, that have been derived
from the discovery and invention of what, for