WASTE OF MANURE.
[What are the first causes of loss of manure?
What is _evaporation_?]
The loss of manure is a subject which demands most serious attention.
Until within a few years, little was known about the true character of
manures, and consequently, of the importance of protecting them against
loss.
The first causes of waste are _evaporation_ and _leaching_.
EVAPORATION.
[Name a solid body which evaporates.
What takes place when a dead animal is exposed to the atmosphere for a
sufficient time?
What often assist the evaporation of solids?]
Evaporation is the changing of a solid or liquid body to a vapory form.
Thus common smelling salts, a solid, if left exposed, passes into the
atmosphere in the form of a gas or vapor. Water, a liquid, evaporates,
and becomes a vapor in the atmosphere. This is the case with very many
substances, and in organic nature, both solid and liquid, they are
liable to assume a gaseous form, and become mixed with the atmosphere.
They are not destroyed, but are merely changed in form.
As an instance of this action, suppose an animal to die and to decay on
the surface of the earth. After a time, the flesh will entirely
disappear, but is not lost. It no longer exists as the flesh of an
animal, but its carbon, hydrogen, oxygen, and nitrogen, still exist in
the air. They have been liberated from the attractions which held them
together, and have passed away; but (as we already know from what has
been said in a former section) they are ready to be again taken up by
plants, and pressed into the service of life.
The evaporation of liquids may take place without the aid of any thing
but heat; still, in the case of solids, it is often assisted by decay
and combustion, which break up the bonds that hold the constituents of
bodies together, and thus enable them to return to the atmosphere, from
which they were originally derived.
[What is the cause of odor?
When we perceive an odor, what is taking place?
Why do manures give off offensive odors?
How may we detect ammonia escaping from manure?]
It must be recollected that every thing, which has an _odor_ (or can be
smelled), is evaporating. The odor is caused by parts of the body
floating in the air, and acting on the nerves of the nose. This is an
invariable rule; and, when we perceive an odor, we may be sure that
parts of the material, from which it emanates, are escaping. If we
perceive the odor of an apple, it is because parts of the volatile oils
of the apple enter the nose. The same is true when we smell hartshorn,
cologne, etc.
Manures made by animals have an offensive odor, simply because volatile
parts of the manure escape into the air, and are therefore made
perceptible. All organic parts in turn become volatile, assuming a
gaseous form as they decompose.
We do not see the gases rising, but there are many ways by which we can
detect them. If we wave a feather over a manure heap, from which ammonia
is escaping, the feather having been recently dipped in manure, white
fumes will appear around the feather, being the muriate of ammonia
formed by the union of the escaping gas with the muriatic acid. Not only
ammonia, but also carbonic acid, and other gases which are useful to
vegetation escape, and are given to the winds. Indeed it may be stated
in few words that all of the organic part of _plants_ (all that was
obtained from the air, water, and ammonia), constituting more than nine
tenths of their dry weight, may be evaporated by the assistance of decay
or combustion. The organic part of _manures_ may be lost in the same
manner; and, if the process of decomposition be continued long enough,
nothing but a mass of mineral matter will remain, except perhaps a small
quantity of carbon which has not been resolved into carbonic acid.
[What remains after manure has been long exposed to
decomposition?
What gaseous compounds are formed by the decomposition of manures?]
The proportion of solid manure lost by evaporation (made by the
assistance of decay), is a very large part of the whole. Manure cannot
be kept a single day in its natural state without losing something. It
commences to give out an offensive odor immediately, and this odor is
occasioned, as was before stated, by the loss of some of its fertilizing
parts.
Animal manure contains, as will be seen by reference to p. 100, all of
the substances contained in plants, though not always in the correct
relative proportions to each other. When decomposition commences, the
carbon unites with the oxygen of the air, and passes off as carbonic
acid; the hydrogen and oxygen combine to form water (which evaporates),
and the _nitrogen is mostly resolved into ammonia, which escapes into
the atmosphere_.
[Describe fire-fanging.
What takes place when animal manure is exposed in an open barn-yard?
What does liquid manure lose by evaporation?]
If manure is thrown into heaps, it often ferments so rapidly as to
produce sufficient heat to set fire to some parts of the manure, and
cause it to be thrown off with greater rapidity. This may be observed in
nearly all heaps of animal excrement. When they have lain for some time
in mild weather, gray streaks of _ashes_ are often to be seen in the
centre of the pile. The organic part of the manure having been _burned_
away, nothing but the ash remains,--this is called _fire-fanging_.
Manures kept in cellars without being mixed with refuse matter are
subject to the same losses.
When kept in the yard, they are still liable to be lost by evaporation.
They are here often saturated with water, and this water in its
evaporation carries away the ammonia, and carbonic acid which it has
obtained from the rotting mass. The evaporation of the water is rapidly
carried on, on account of the great extent of surface. The whole mass is
spongy, and soaks the liquids up from below (through hollow straws,
etc.), to be evaporated at the surface on the same principle as causes
the wick of a lamp to draw up the oil to supply fuel for the flame.
LIQUID MANURE containing large quantities of nitrogen, and forming much
ammonia, is also liable to lose all of its organic part from evaporation
(and fermentation), so that it is rendered as much less valuable as is
the solid dung.[X]
[When does the waste of exposed manure commence?
What does economy of manure require?
What is the effect of leaching?
Give an illustration of leaching.]
From these remarks, it may be justly inferred that a very large portion
of the _value_ of solid and liquid manure as ordinarily kept is lost by
evaporation in a sufficient length of time, depending on circumstances,
whether it be three months or several years. The wasting commences as
soon as the manure is dropped, and continues, except in very cold
weather, until the destruction is complete. Hence we see that true
economy requires that the manures of the stable, stye, and
poultry-house, should be protected from evaporation (as will be
hereafter described), as soon as possible after they are made.
LEACHING.
The subject of _leaching_ is as important in considering the _inorganic_
parts of manures as evaporation is to the organic, while leaching also
affects the organic gases, they being absorbed by water in a great
degree.
A good illustration of leaching is found in the manufacture of potash.
When water is poured over wood-ashes, it dissolves their potash which
it carries through in solution, making ley. If ley is boiled to dryness,
it leaves the potash in a solid form, proving that this substance had
been dissolved by the water and removed from the insoluble parts of the
ashes.
[How does water affect decomposing manures?
Does continued decomposition continue to prepare material to be leached
away?
How far from the surface of the soil may organic constituents be carried
by water?]
In the same way water in passing through manures takes up the soluble
portions of the ash as fast as liberated by decomposition, and carries
them into the soil below; or, if the water runs off from the surface,
they accompany it. In either case they are lost to the manure. There is
but a small quantity of ash exposed for leaching in recent manures; but,
as the decomposition of the organic part proceeds, it continues to
develope it more and more (in the same manner as burning would do, only
slower), thus preparing fresh supplies to be carried off with each
shower. In this way, while manures are largely injured by evaporation,
the soluble inorganic parts are removed by water until but a small
remnant of its original fertilizing properties remains.
[What arrests their farther progress?
What would be the effect of allowing these matters to filter downwards?
What does evaporation remove from manure? Leaching?]
It is a singular fact concerning leaching, that water is able to carry
no part of the organic constituents of vegetables more than about
thirty-four inches below the surface in a fertile soil. They would
probably be carried to an unlimited distance in pure sand, as it
contains nothing which is capable of arresting them; but, in most soils,
the clay and carbon which they contain retain all of the ammonia; also
nearly all of the matters which go to form the inorganic constituents of
plants within about the above named distance from the surface of the
soil. If such were not the case, the fertility of the earth must soon be
destroyed, as all of those elements which the soil must supply to
growing plants would be carried down out of the reach of roots, and
leave the world a barren waste, its surface having lost its elements of
fertility, while the downward filtration of these would render the water
of wells unfit for our use. Now, however, they are all retained near the
surface of the soil, and the water issues from springs comparatively
pure.
EVAPORATION removes from manure--
Carbon, in the form of carbonic acid.
Hydrogen and oxygen, in the form of water.
Nitrogen, in the form of ammonia.
LEACHING removes from manure--
The soluble and most valuable parts of the ash in solution in
water, besides carrying away some of the named above forms of
organic matter.
FOOTNOTES:
[X] It should be recollected that every bent straw may act as a syphon,
and occasion much loss of liquid manure.