CHAPTER III
USES OF INORGANIC MATTER
What effect has clay besides the one already named?
How does it compare with charcoal for this purpose?
The offices performed by the inorganic constituents of the soil are many and important.
These, as well as the different conditions in which the bodies exist, are necessary to be thoroughly studied.
Those parts which constitute the larger proportion of the soil, namely the clay, sand, and limy portions, are useful for purposes which have been named in the first part of this section, while the clay has an additional effect in the absorption of ammonia.
For this purpose, it is as effectual as charcoal, the gases escaping from manures, as well as those existing in the atmosphere, and in rain-water, being arrested by clay as well as charcoal.20
What particular condition of inorganic matter is requisite for fertility?
What is the fixed rule with regard to this?
What is the condition of the alkalies in most of their combinations? Of the acids?
What is said of phosphate of lime?
The more minute ingredients of the soil—those which enter into the construction of plants—exist in conditions which are more or less favorable or injurious to vegetable growth. The principal condition necessary to fertility is capacity to be dissolved, it being (so far as we have been able to ascertain) a fixed rule, as was stated in the first section, that no mineral substance can enter into the roots of a plant except it be dissolved in water.
The alkalies potash, soda, lime, and magnesia, are in nearly all of their combinations in the soil sufficiently soluble for the purposes of growth.
The acids are, as will be recollected, sulphuric and phosphoric. These exist in the soil in combination with the alkalies, as sulphates and phosphates, which are more or less soluble under natural circumstances. Phosphoric acid in combination with lime as phosphate of lime is but slightly soluble; but, when it exists in the compound known as super-phosphate of lime, it is much more soluble, and consequently enters into the composition of plants with much greater facility. This matter will be more fully explained in the section on manures.
How may silica be rendered soluble?
What is the condition of chlorine in the soil?
Do peroxide and protoxide of iron affect plants in the same way?
How would you treat a soil containing protoxide of iron?
On what does the usefulness of all these matters in the soil depend?
The neutrals, silica, chlorine, oxide of iron, and oxide of manganese, deserve a careful examination. Silica exists in the soil usually in the form of sand, in which it is, as is well known, perfectly insoluble; and, before it can be used by plants, which often require it in large quantities, it must be made soluble, which is done by combining it with an alkali.
For instance, if the silica in the soil is insoluble, we must make an application of an alkali, such as potash, which will unite with the silica, and form the silicate of potash, which is in the exact condition to be dissolved and carried into the roots of plants.
Chlorine in the soil is probably always in an available condition.
Oxide of iron exists, as has been previously stated, usually in the form of the peroxide (or red oxide). Sometimes, however, it exists in the form of the protoxide (or black oxide), which is poisonous to plants, and renders the soil unfertile. By loosening the soil in such a manner as to admit air and water, this compound takes up more oxygen, which renders it a peroxide, and makes it available for plants. The oxide of manganese is probably of little consequence.
The usefulness of all of these matters in the soil depends on their exposure; if they are in the interior of particles, they cannot be made use of; while, if the particles are so pulverized that their constituents are exposed, they become available, because water can immediately attack to dissolve, and carry them into roots.
What is one of the chief offices of plowing and hoeing?
Is the subsoil usually different from the surface soil?
What circumstances have occasioned the difference? In what way?
This is one of the great offices of plowing and hoeing; the lumps of soil being thereby more broken up and exposed to the action of atmospheric influences, which are often necessary to produce a fertile condition of soil, while the trituration of particles reduces them in size.
SUBSOIL
May the subsoil be made to resemble the surface soil?
May all soils be brought to the highest state of fertility?
On what examination must improvement be based?
What is the difference between the soil of some parts of Massachusetts and that of the Miami valley?
The subsoil is usually of a different character from the surface soil, but this difference is more often the result of circumstances than of formation. The surface soil from having been long cultivated has been more opened to the influences of the air than is the case with the subsoil, which has never been disturbed so as to allow the same action. Again the growth of plants has supplied the surface soil with roots, which by decaying have given it organic matter, thus darkening its color, rendering it warmer, and giving greater ability to absorb heat and moisture, and to retain manures. All of these effects render the surface soil of a more fertile character than it was before vegetable growth commenced; and, where frequent cultivation and manures have been applied, a still greater benefit has resulted. In most instances the subsoil may by the same means be gradually improved in condition until it equals the surface soil in fertility. The means of producing this result, also farther accounts of its advantages, will be given under the head of Cultivation (Sect. IV.)
IMPROVEMENT
From what has now been said of the character of the soil, it must be evident that, as we know the causes of fertility and barrenness, we may by the proper means improve the character of all soils which are not now in the highest state of fertility.
Chemical analysis will tell us the composition of a soil, and an examination, such as any farmer may make, will inform us of its deficiencies in mechanical character, and we may at once resort to the proper means to secure fertility. In some instances the soil may contain every thing that is required, but not in the necessary condition. For instance, in some parts of Massachusetts, there are nearly barren soils which show by analysis precisely the same chemical composition as the soil of the Miami valley of Ohio, one of the most fertile in the world. The cause of this great difference in their agricultural capabilities, is that the Miami soil has its particles finely pulverized; while in the Massachusetts soil the ingredients are combined within particles (such as pebbles, etc.), where they are out of the reach of roots.
Why do soils of the same degree of fineness sometimes differ in fertility?
Can soils always be rendered fertile with profit?
Can we determine the cost before commencing the work?
What must be done before a soil can be cultivated understandingly?
What must be done to keep up the quality of the soil?
In other cases, we find two soils, which are equally well pulverized, and which appear to be of the same character, having very different power to support crops. Chemical analysis will show in these instances a difference of composition.
All of these differences may be overcome by the use of the proper means. Sometimes it could be done at an expense which would be justified by the result; and, at others, it might require too large an outlay to be profitable. It becomes a question of economy, not of ability, and science is able to estimate the cost.
Soil cannot be cultivated understandingly until it has been subjected to such an examination as will tell us exactly what is necessary to render it fertile. Even after fertility is perfectly restored it requires thought and care to maintain it. The ingredients of the soil must be returned in the form of manures as largely as they are removed by the crop, or the supply will eventually become too small for the purposes of vegetation.
SECTION THIRD.
MANURES
CHAPTER I
CHARACTER AND VARIETIES OF MANURES
What must a farmer know in order to avoid failures?
Can this be learned entirely from observation?
What kind of action have manures?
Give examples of each of these.
May mechanical effects be produced by chemical action?
How does potash affect the soil?
To understand the science of manures is the most important branch of practical farming. No baker would be called a good practical baker who kept his flour exposed to the sun and rain. No shoemaker would be called a good practical shoemaker, who used morocco for the soles of his shoes, and heavy leather for the uppers. No carpenter would be called a good practical carpenter, who tried to build a house without nails, or other fastenings. So with the farmer. He cannot be called a good practical farmer if he keeps the materials, from which he is to make plants, in such a condition, that they will have their value destroyed, uses them in the wrong places, or tries to put them together without having every thing present that is necessary. Before he can avoid failures with certainty, he must know what manures are composed of, how they are to be preserved, where they are needed, and what kinds are required. True, he may from observation and experience, guess at results, but he cannot know that he is right until he has learned the facts above named. In this section of our work, we mean to convey some of the information necessary to this branch of practical farming.
We shall adopt a classification of the subject somewhat different from that found in most works on manures, but the facts are the same. The action of manures is either mechanical or chemical, or a combination of both. For instance: some kinds of manure improve the mechanical character of the soil, such as those which loosen stiff clay soils, or others which render light sandy soils compact—these are called mechanical manures. Some again furnish food for plants—these are called chemical manures.
Many mechanical manures produce their effects by means of chemical action. Thus potash combines chemically with sand in the soil. In so doing, it roughens the surfaces of the particles of sand, and renders the soil less liable to be compacted by rains. In this manner, it acts as a mechanical manure. The compound of sand and potash,21 as well as the potash alone, may enter into the composition of plants, and hence it is a chemical manure. In other words, potash belongs to both classes described above.
It is important that this distinction should be well understood by the learner, as the words "mechanical" and "chemical" in connection with manures will be made use of throughout the following pages.
What are absorbents?
What kind of manure is charcoal?
There is another class of manures which we shall call absorbents. These comprise those substances which have the power of taking up fertilizing matters, and retaining them for the use of plants. For instance, charcoal is an absorbent. As was stated in the section on soils, this substance is a retainer of all fertilizing gases and many minerals. Other matters made use of in agriculture have the same effect. These absorbents will be spoken of more fully in their proper places.
TABLE
Into what classes may manures be divided?
What are organic manures?
Inorganic? Atmospheric?
Manures may be divided into three classes, viz.: organic, inorganic, and atmospheric.
Organic manures comprise all animal and vegetable matters which are used to fertilize the soil, such as dung, muck, etc.
Inorganic manures are those which are of a purely mineral character, such as lime, ashes, etc.
Atmospheric manures consist of those organic manures which are in the form of gases in the atmosphere, and which are absorbed by rains and carried to the soil. These are of immense importance. The ammonia and carbonic acid in the air are atmospheric manures.
CHAPTER II
EXCREMENTS OF ANIMALS
Of what is animal excrement composed?
Explain the composition of the food of animals.
What does hay contain?
To what does Liebig compare the consumption of food by animals, and why?
The first organic manure which we shall examine, is animal excrement.
This is composed of those matters which have been eaten by the animal as food, and have been thrown off as solid or liquid manure. In order that we may know of what they consist, we must refer to the composition of food and examine the process of digestion.
The food of animals, we have seen to consist of both organic and inorganic matter. The organic part may be divided into two classes, i. e., that portion which contains nitrogen—such as gluten, albumen, etc., and that which does not contain nitrogen—such as starch, sugar, oil, etc.
The inorganic part of food may also be divided into soluble matter and insoluble matter.
DIGESTION AND ITS PRODUCTS
Of what does that part of dung consist which resembles soot?
What else does the dung contain?
In what manner does the digested part of food escape from the body?
Let us now suppose that we have a full-grown ox, which is not increasing in any of his parts, but only consumes food to keep up his respiration, and to supply the natural wastes of his body. To this ox we will feed a ton of hay which contains organic matter, with and without nitrogen, and soluble and insoluble inorganic substances. Now let us try to follow it through its changes in the animal, and observe its destination. Liebig compares the consumption of food by animals to the imperfect burning of wood in a stove, where a portion of the fuel is resolved into gases and ashes (that is, it is completely burned), and another portion, which is not thoroughly burned, passes off as soot. In the animal action in question, the food undergoes changes which are similar to this burning of wood. A part of the food is digested and taken up by the blood, while another portion remains undigested, and passes the bowels as solid dung—corresponding to soot. This part of the dung then, we see is merely so much of the food as passes through the system without being materially changed. Its nature is easily understood. It contains organic and inorganic matter in nearly the same condition as they existed in the hay. They have been rendered finer and softer, but their chemical character is not materially altered. The dung also contains small quantities of nitrogenous matter, which leaked out, as it were, from the stomach and intestines. The digested food, however, undergoes further changes which affect its character, and it escapes from the body in three ways—i. e., through the lungs, through the bladder, and through the bowels. It will be recollected from the first section of this book, p. 22, that the carbon in the blood of animals, unites with the oxygen of the air drawn into the lungs, and is thrown off in the breath as carbonic acid. The hydrogen and oxygen unite to form a part of the water which constitutes the moisture of the breath.
Explain the escape of carbon, hydrogen and oxygen.
What becomes of the nitrogenous parts?
How is the soluble ash of the digested food parted with?
The insoluble?
If any portions of the food are not returned in the dung, how are they disposed of?
That portion of the organic part of the hay which has been taken up by the blood of the ox, and which does not contain nitrogen (corresponding to the first class of proximates, as described in Sect. I), is emitted through the lungs. It consists, as will be recollected, of carbon, hydrogen and oxygen, and these assume, in respiration, the form of carbonic acid and water.
The organic matter of the digested hay, in the blood, which contains nitrogen (corresponding to the second class of proximates, described in Sect. I), goes to the bladder, where it assumes the form of urea—a constituent of urine or liquid manure.
We have now disposed of the imperfectly digested food (dung), and of the organic matter which was taken up by the blood. All that remains to be examined is the inorganic or mineral matter in the blood, which would have become ashes, if the hay had been burned. The soluble part of this inorganic matter passes into the bladder, and forms the inorganic part of urine. The insoluble part passes the bowels, in connection with the dung.
How is their place supplied?
Is food put out of existence when it is fed to animals?
What does the solid dung contain? Liquid manure? The breath?
If any of the food taken up by the blood is not returned as above stated, it goes to form fat, muscle, hair, bones, or some other part of the animal, and as he is not growing (not increasing in weight) an equivalent amount of the body of the animal goes to the manure to take the place of the part retained.22
We now have our subject in a form to be readily understood. We learn that when food is given to animals it is not put out of existence, but is merely changed in form; and that in the impurities of the breath, we have a large portion of those parts of the food which plants obtain from air and from water; while the solid and liquid excrements contain all that was taken by the plants from the soil and manures.
The Solid Dung contains the undigested parts of the food, the insoluble parts of the ash, and the nitrogenous matters which have escaped from the digestive organs.
"Liquid Manure" the nitrogenous or second class of proximates of the digested food, and the soluble parts of the ash.
The Breath contains the first class of proximates, those which contain carbon, hydrogen and oxygen, but no nitrogen.23
CHAPTER III
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.24
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.