ABSORBENTS.
[What substances are called absorbents?
What is the most important of these?
What substances are called charcoal in agriculture?
How is vegetable matter rendered useful as charcoal?]
Before considering farther the subject of animal excrement, it is
necessary to examine a class of manures known as _absorbents_. These
comprise all matters which have the power of absorbing, or soaking up,
as it were, the gases which arise from the evaporation of solid and
liquid manures, and retaining them until required by plants.
The most important of these is undoubtedly _carbon_ or charcoal.
CHARCOAL.
_Charcoal_, in an agricultural sense, means all forms of carbon, whether
as peat, muck, charcoal dust from the spark-catchers of locomotives,
charcoal hearths, river and swamp deposits, leaf mould, decomposed spent
tanbark or sawdust, etc. In short, if any vegetable matter is decomposed
with the partial exclusion of air (so that there shall not be oxygen
enough supplied to unite with all of the carbon), a portion of its
carbon remains in the exact condition to serve the purposes of charcoal.
[What is the first-named effect of charcoal? The second?
Third? Fourth?
Explain the first action.]
The offices performed in the soil by carbonaceous matter were fully
explained in a former section (p. 79, Sect. 2), and we will now examine
merely its action with regard to manures. When properly applied to
manures, in compost, it has the following effects:
1. It absorbs and retains the fertilizing gases evaporating from
decomposing matters.
2. It acts as a _divisor_, thereby reducing the strength (or intensity)
of powerful manures--thus rendering them less likely to injure the roots
of plants; and also increases their bulk, so as to prevent _fire
fanging_ in composts.
3. It in part prevents the leaching out of the soluble parts of the ash.
4. It keeps the compost moist.
The first-named office of charcoal, _i. e._, absorbing and retaining
gases, is one of the utmost importance. It is this quality that gives to
it so high a position in the opinion of all who have used it. As was
stated in the section on soils, carbonaceous matter seems to be capable
of absorbing every thing which may be of use to vegetation. It is a
grand purifier, and while it prevents offensive odors from escaping, it
is at the same time storing its pores with food for the nourishment of
plants.
[Explain its action as a divisor.
How does charcoal protect composts against injurious action of rains?
How does it keep them moist?]
2d. In its capacity as a _divisor_ for manures, charcoal should be
considered as excellent in all cases, especially to use with strongly
concentrated (or heating) animal manures. These, when applied in their
natural state to the soil, are very apt to injure young roots by the
violence of their action. When mixed with a divisor, such manures are
_diluted_, made less active, and consequently less injurious. In
composts, manures are liable, as has been before stated, to become
burned by the resultant heat of decomposition; this is called _fire
fanging_, and is prevented by the liberal use of divisors, because, by
increasing the bulk, the heat being diffused through a larger mass,
becomes less intense. The same principle is exhibited in the fact that
it takes more fire to boil a cauldron of water than a tea-kettle full.
3d. Charcoal has much power to arrest the passage of mineral matters in
solution; so much so, that compost heaps, well supplied with muck, are
less affected by rains than those not so supplied. All composts,
however, should be kept under cover.
4th. Charcoal keeps the compost moist from the ease with which it
absorbs water, and its ability to withstand drought.
[What source of carbon is within the reach of most farmers?
What do we mean by muck?
Of what does it consist?
How does it differ in quality?]
With these advantages before us, we must see the importance of an
understanding of the modes for obtaining charcoal. Many farmers are so
situated that they can obtain sufficient quantities of charcoal dust.
Others have not equal facilities. Nearly all, however, can obtain
_muck_, and to this we will now turn our attention.
MUCK, AND THE LIME AND SALT MIXTURE.
[What is the first step in preparing muck for decomposition?
With what proportion of the lime and salt mixture should it be
composted?
Why should this compost be made under cover?
What is this called after decomposition?
Why should we not use muck immediately after taking it from the swamp?]
By _muck_, we mean the vegetable deposits of swamps and rivers. It
consists of decayed organic substances, mixed with more or less earth.
Its principal constituent is _carbon_, in different degrees of
development, which has remained after the decomposition of vegetable
matter. Muck varies largely in its quality, according to the amount of
carbon which it contains, and the perfection of its decomposition. The
best muck is usually found in comparatively dry locations, where the
water which once caused the deposit has been removed. Muck which has
been long in this condition, is usually better decomposed than that
which is saturated with water. The muck from swamps, however, may soon
be brought to the best condition. It should be thrown out, if possible,
at least one year before it is required for use (a less time may
suffice, except in very cold climates) and left, in small heaps or
ridges, to the action of the weather, which will assist in pulverizing
it, while, from having its water removed, its decomposition goes on more
rapidly.
After the muck has remained in this condition a sufficient length of
time, it may be removed to the barn-yard and composted with the lime and
salt mixture (described on page 115) in the proportion of one cord of
muck to four bushels of the mixture. This compost ought to be made under
cover, lest the rain leach out the constituents of the mixture, and thus
occasion loss; at the end of a month or more, the muck in the compost
will have been reduced to a fine pulverulent mass, nearly equal to
charcoal dust for application to animal excrement. When in this
condition it is called _prepared_ muck, by which name it will be
designated in the following pages.
Muck should not be used immediately after being taken from the swamp, as
it is then almost always _sour_, and is liable to produce sorrel. Its
_sourness_ is due to _acids_ which it contains, and these must be
rectified by the application of an alkali, or by long exposure to the
weather, before the muck is suitable for use.
LIME AND SALT MIXTURE.
[What proportions of lime and salt are required for the
decomposing mixture?
Explain the process of making it.
Why should it be made under cover?]
The lime and salt mixture, used in the decomposition of muck, is made in
the following manner:
RECIPE.--Take _three_ bushels of shell lime, _hot from the kiln_, or as
fresh as possible, and slake it with water in which _one_ bushel of salt
has been dissolved.
Care must be taken to use only so much water as is necessary to dissolve
the salt, as it is difficult to induce the lime to absorb a larger
quantity.
In dissolving the salt, it is well to hang it in a basket in the upper
part of the water, as the salt water will immediately settle towards the
bottom (being heavier), and allow the freshest water to be nearest to
the salt. In this way, the salt may be all dissolved, and thus make the
brine used to slake the lime. It may be necessary to apply the brine at
intervals of a day or two, and to stir the mass often, as the amount of
water is too great to be readily absorbed.
This mixture should be made under cover, as, if exposed, it would obtain
moisture from rain or dew, which would prevent the use of all the
brine. Another objection to its exposure to the weather is its great
liability to be washed away by rains. It should be at least ten days old
before being used, and would probably be improved by an age of three or
four months, as the chemical changes it undergoes will require some time
to be completed.
[Explain the character of this mixture as represented in the
diagram. (Black board.)]
The character of this mixture may be best described by the following
diagram:--
We have originally--
+----------------------------------+
| |
Lime-+ Salt
| consisting of
| +---Chlorine } Chloride
| | and } of
| | +-Sodium. } Sodium.
| | | --Carbonic acid
| | | and
| | | --Oxygen in the air.
+-Chloride of lime.-+ |
+-Carbonate of Soda.
[Y]
The lime unites with the chlorine of the salt and forms _chloride of
lime_.
The sodium, after being freed from the chlorine, unites with the oxygen
of the air and forms soda, which, combining with the carbonic acid of
the atmosphere, forms carbonate of soda.
Chloride of lime and carbonate of soda are better agents in the
decomposition of muck than pure salt and lime; and, as these compounds
are the result of the mixture, much benefit ensues from the operation.
When _shell_ lime cannot be obtained, Thomaston, or any other very pure
lime, will answer, though care must be taken that it do not contain much
magnesia.
LIME.
[What effect has lime on muck?
On what does the energy of this effect depend?
Why should a compost of muck and lime be protected from rain?]
Muck may be decomposed by the aid of other materials. _Lime_ is very
efficient, though not as much so as when combined with salt. The action
of lime, when applied to the muck, depends very much on its condition.
Air-slaked lime (carbonate of lime), and hydrate of lime, slaked with
water, have but a limited effect compared with lime freshly burned and
applied in a caustic (or pure) form. When so used, however, the compost
should not be exposed to rains, as this would have a tendency to make
_mortar_ which would harden it.
POTASH.
[Is potash valuable for this use?
From what sources may potash be obtained?
In what proportion should ashes be applied to muck? Sparlings?]
_Potash_ is a very active agent in decomposing vegetable matter, and may
be used with great advantage, especially where an analysis of the soil
which is to be manured shows a deficiency of potash.
_Unleached_ wood ashes are generally the best source from which to
obtain this, and from five to twenty-five bushels of these mixed with
one cord of muck will produce the desired result.[Z]
The sparlings (or refuse) of potash warehouses may often be purchased at
sufficiently low rates to be used for this purpose, and answer an
excellent end. They may be applied at the rate of from twenty to one
hundred pounds to each cord of muck.
* * * * *
By any of the foregoing methods, muck may be _prepared_ for use in
composting.
FOOTNOTES:
[Y] There is, undoubtedly, some of this lime which does not unite with
the chlorine; this, however, is still as valuable as any lime.
[Z] _Leached_ ashes will not supply the place of these, as the leaching
has deprived them of their potash.