The Elements of 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 (#x3_x_3_i171), 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 (#x4_x_4_i198)) 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—

[Y] There is, undoubtedly, some of this lime which does not unite with the chlorine; this, however, is still as valuable as any lime.

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.