NATURAL FERTILIZERS—GUANO
“Plant-life finds a part of its sustenance provided by nature in the
atmosphere; it finds carbonic acid gas, whence it derives the carbon it
requires; but the care and ingenuity of man have to supplement these
natural resources by providing fertilizers.
“One of the chief of these fertilizers, farm manure, is furnished by
the bedding and excrement of animals. To obtain an excellent dressing
of this sort it is customary to use for bedding, as far as possible,
the straw from grain, since this, being composed of hollow stalks, is
capable of holding considerable moisture. But, as in certain cases
straw would hardly be able to absorb all the fluid matter, it is well
to make a trench in the stable and thus carry off the excess of liquid
to a reservoir outside, where another heap of straw or similar material
is in readiness to receive it. Then, at a distance from all rain-spouts
and gutters, and in the shade of trees, a substantial layer of clay is
spread on the ground, and on this is erected the pile of manure. All
around it is dug a little trench which conducts the brown liquid that
oozes from the manure, and that is known as liquid manure, into a hole
large enough to admit of the use of a bucket in drawing out the liquid.
“Liquid manure is composed of the fluid matter with which the bedding
is steeped, and it holds in solution a great part of the nutritive
constituents of the manure. Agriculture knows no richer fertilizer.
Hence care should be taken not to let it go to waste in neighboring
ditches or soak into the ground. That is why the pile is placed on a
layer of clay, which keeps the liquid manure from soaking into the
ground where it would be wasted; and it is also the reason for digging
a trench to receive this fluid matter and conduct it to the hole. When
this hole is full the liquid manure is drawn out with a bucket and
thrown back on to the dung-hill.
“Nor is that the whole of the story. A slow combustion will soon begin
throughout the pile of manure; its mass will ferment and become heated,
and as a consequence the nitrogenous constituents will decompose and
will liberate ammonia, which will escape into the air and be lost if
the fermentation is excessive. It is to avoid too rapid a heating that
the manure-pile is placed in the shade and not under the direct rays of
the sun. Moreover, the liquid manure thrown on to the heap from time to
time also moderates the fermenting process.
“Compare this careful method with the practice on most farms, where the
manure is heaped up without any precaution, without shelter from the
sun, unprotected from the drenching rains, which wash away the soluble
constituents. Think of those rivulets of liquid manure trickling away
in this direction and that, and collecting here and there in puddles of
infection. See how all the inmates of the poultry-yard scratch at the
heap, turning over and scattering its contents, and thus causing the
ammonia to escape into the atmosphere. Can such a dung-hill be as
valuable as one that is attended to properly?
“Liquid manure being the richest part of the whole pile, care should be
taken not to let escape what the bedding does not absorb. It should be
first diluted with water and then applied to the growing crops. When it
is desired for use in non-liquid form, it should be mixed with enough
earth to absorb it, and the result is an excellent fertilizer.
“In summer it is not unusual to enclose with hurdles a piece of land
soon to be cultivated, and into this enclosure a flock of sheep is
driven to pass the night under the care of the shepherd in his movable
hut, and with the protection of trusty dogs well able to cope with any
marauding wolves. The next night the flock is quartered in another
spot, and so on until the entire field has thus served, a little at a
time, as stable for the flock. The purpose of this procedure is to
utilize the excrement, both solid and liquid, left behind by the flock.
In one night a sheep can fertilize a square meter of surface. This
method of fertilizing is very effective because of the complete
absorption of the fluid matter by the soil.
“Off the coast of Peru in South America are several small islands which
form a common rendezvous for great numbers of sea-birds. Birds that
frequent the sea are all notorious for their insatiable appetite.
Constantly in search of fish, which they live on, they spend the day
exploring the surface of the waters at immense distance from land.
Nature has endowed them with prodigious flying power. To these
indefatigable rovers an aërial promenade of some hundreds of leagues
before dinner is a mere nothing. Scattered during the day in all
directions in quest of prey, they reach the islets in the evening to
spend the night, arriving in flocks so dense as to darken the sky.
Being well fed, thanks to their foraging excursions, they cover the
ground at night with a thick layer of excrement. And as this has been
going on century after century ever since the world was made, these
deposits, piled one on another, have at last become massive beds twenty
or thirty meters thick, and so hard, so compact, that to break them it
is necessary to use a pick or a petard, just as one would in quarrying
stone. Workmen operate this dung mine, and vessels from all parts of
the world fetch cargoes of this valuable material, which is called
guano. This enormous mass of dung, which has by the lapse of ages been
turned into a sort of whitish loam, gives Peru an annual revenue
amounting to sixty millions of francs.
“Guano is the strongest fertilizer known to agriculture. It is
scattered broadcast over the field when vegetation is starting, and for
the best results a rather damp time is chosen for this work in order
that the moisture may convey to the roots of the plants, by gradual
infiltration, the soluble constituents of the fertilizer. The action of
guano on vegetation is of the promptest, most powerful sort.”