The Elements of Agriculture
- -
- 100%
- +
Why does a wet cloth on the head make it cooler when fanned?
How does this principle apply to the soil?
17. The evaporation of water, and the consequent abstraction of heat from the soil, is in a great measure prevented by draining the water out at the bottom of the soil, instead of leaving it to be dried off from the surface.
When water assumes the gaseous (or vapory) form, it takes up 1723 times as much heat as it contained while a liquid. A large part of this heat is derived from surrounding substances. When water is sprinkled on the floor, it cools the room; because, as it becomes a vapor, it takes heat from the room. The reason why vapor does not feel hotter than liquid water is, that, while it contains 1723 times as much heat, it is 1723 as large. Hence, a cubic inch of vapor, into which we place the bulb of a thermometer, contains no more heat than a cubic inch of water. The principle is the same in some other cases. A sponge containing a table-spoonful of water is just as wet as one twice as large and containing two spoonsful.
If a wet cloth be placed on the head, and the evaporation of its water assisted by fanning, the head becomes cooler—a portion of its heat being taken to sustain the vapory condition of the water.
The same principle holds true with the soil. When the evaporation of water is rapidly going on, by the assistance of the sun, wind, etc., a large quantity of heat is abstracted, and the soil becomes cold.
When there is no evaporation taking place, except of water which has been deposited on the lower portions of soil, and carried to the surface by capillary attraction (as is nearly true on under-drained soils), the loss of heat is compensated by that taken from the moisture in the atmosphere by the soil, in the above-named manner.
This cooling of the soil by the evaporation of water, is of very great injury to its powers of producing crops, and the fact that under-drains avoid it, is one of the best arguments in favor of their use. Some idea may, perhaps, be formed of the amount of heat taken from the soil in this way, from the fact that, in midsummer, 25 hogsheads of water may be evaporated from a single acre in twelve hours.
When rains are allowed to enter the soil, how do they benefit it?
How do under-drains prevent the formation of a crust on the surface of a soil?
18. When not saturated with water the soil admits the water of rains, etc., which bring with them fertilizing gases from the atmosphere, to be deposited among the absorbent parts of soil, and given up to the necessities of the plant. When this rain falls on lands already saturated, it cannot enter the soil, but must run off from the surface, or be removed by evaporation, either of which is injurious. The first, because fertilizing matter is washed away. The second, because the soil is deprived of necessary heat.
19. The formation of crust on the surface of the soil is due to the evaporation of water, which is drawn up from below by capillary attraction. It arises from the fact that the water in the soil is saturated with mineral substances, which it leaves at its point of evaporation at the surface. This soluble matter from below, often forms a very hard crust, which is a complete shield to prevent the admission of air with its ameliorating effects, and should, as far as possible, be avoided. Under-draining is the best means of doing this, as it is the best means of lessening the evaporation.
The foregoing are some of the more important reasons why under-draining is always beneficial. Thorough experiments have amply proved the truth of the theory.
What kinds of soil are benefited by under-draining?
The kinds of soil benefited by under-draining are nearly as unlimited as the kinds of soil in existence. It is a common opinion, among farmers, that the only soils which require draining are those which are at times covered with water, such as swamps and other low lands; but the facts stated in the early part of this chapter, show us that every kind of soil—wet, dry, compact, or light—receives benefit from the treatment. The fact that land is too dry, is as much a reason why it should be drained, as that it is too wet, as it overcomes drought as effectually as it removes the injurious effects of too much water.
All soils in which the water of heavy rains does not immediately pass down to a depth of at least thirty inches, should be under-drained, and the operation, if carried on with judgment, would invariably result in profit.
What do English farmers name as the profits of under-draining?
What stand has been taken by the English government with regard to under-draining?
Of the precise profits of under-draining this is not the place to speak: many of the agricultural papers contain numerous accounts of its success. It may be well to remark here, that many English farmers give it, as their experience, that under-drains pay for themselves every three years, or that they produce a perpetual profit of 33⅓ per cent., or their original cost. This is not the opinion of theorists and book farmers. It is the conviction of practical men, who know, from experience, that under-drains are beneficial.
The best evidence of the utility of under-draining is the position, with regard to it, which has been taken by the English national government, which affords much protection to the agricultural interests of her people—a protection which in this country is unwisely and unjustly withheld.
In England a very large sum from the public treasury has been appropriated as a fund for loans, on under-drains, which is lent to farmers for the purpose of under-draining their estates, the only security given being the increased value of the soil. The time allowed for payments is twenty years, and only five per cent. interest is charged. By the influence of this patronage, the actual wealth of the kingdom is being rapidly increased, while the farmers themselves, can raise their farms to any desired state of fertility, without immediate investment.
How does under-draining affect the healthfulness of marshy countries?
Describe the sub-soil plow.
The best proof that the government has not acted injudiciously in this matter is, that private capitalists are fast employing their money in the same manner, and loans on under-drains are considered a very safe investment.
There is no doubt that we may soon have similar facilities for improving our farms, and when we do, we shall find that it is unnecessary to move West to find good soil. The districts nearer market, where the expense of transportation is much less, may, by the aid of under-drains, and a judicious system of cultivation, be made equally fertile.
One very important, though not strictly agricultural, effect of thorough drainage is its removal of certain local diseases, peculiar to the vicinity of marshy or low moist soils. The health-reports in several places in England, show that where fever and ague was once common, it has almost entirely disappeared since the general use of under-drains in those localities.
CHAPTER IV
SUB-SOIL PLOWINGDescribe the Mapes plow.
Why is the motion in the soil of one and a half inches sufficient?
How does the oxidation of the particles of the soil resemble the rusting of cannon balls in a pile?
The sub-soil plow is an implement differing in figure from the surface plow. It does not turn a furrow, but merely runs through the subsoil like a mole—loosening and making it finer by lifting, but allowing it to fall back and occupy its former place. It usually follows the surface plow, entering the soil to the depth of from twelve to eighteen inches below the bottom of the surface furrow.
The best pattern now made (the Mapes plow) is represented in the following figure.
Fig. 8.
The Mapes plow and its mode of action. a—Shape of the foot of the plow, b—Its effect on the soil.
The sub-soil plows first made raised the whole soil about eight inches, and required very great power in their use often six, eight, or even ten oxen. The Mapes plow, raising the soil but slightly, may be worked with much less power, and produces equally good results. It may be run to its full depth in most soils by a single yoke of oxen.
Of course a motion in the soil of but one and a half inches is very slight, but it is sufficient to move each particle from the one next to it which, in dry soils, is all that is necessary. Whoever has examined a pile of cannon-balls must have observed that at the points where they touch each other, there is a little rust. In the soil, the same is often the case. Where the particles touch each other, there is such a chemical change produced as renders them fit for the use of plants. While these particles remain in their first position, the changed portions are out of the reach of roots; but, if, by the aid of the sub-soil plow, their position is altered, these parts are exposed for the uses of plants. If we hold in the hand a ball of dry clay, and press it hard enough to produce the least motion among its particles, the whole mass becomes pulverized. On the same principle, the sub-soil plow renders the compact lower soil sufficiently fine for the requirements of fertility.
Why are the benefits of sub-soiling not permanent on wet lands?
Does sub-soiling overcome drought?
How does it deepen the surface soil?
Notwithstanding its great benefits on land, which is sufficiently dry, sub-soiling cannot be recommended for wet lands; for, in such case, the rains of a single season would often be sufficient to entirely overcome its effects by packing the subsoil down to its former hardness.
On lands not overcharged with water, it is productive of the best results, it being often sufficient to turn the balance between a gaining and a losing business in farming.
It increases nearly every effect of under-draining; especially does it overcome drought, by loosening the soil, and admitting air to circulate among the particles of the subsoil and deposit its moisture on the principle described in the chapter on under-draining.
It deepens the surface-soil, because it admits roots into the subsoil where they decay and leave carbon, while the circulation of air so affects the mineral parts, that they become of a fertilizing character. The deposit of carbon gives to the subsoil the power of absorbing, and retaining the atmospheric fertilizers, which are more freely presented, owing to the fact that the air is allowed to circulate with greater freedom. As a majority of roots decay in the surface-soil, they there deposit much mineral matter obtained from the subsoil.
Why is the retention of atmospheric manures ensured by sub-soiling?
Why are organic manures plowed deeply under the soil, less liable to evaporation than when deposited near the surface?
How does sub-soiling resemble under-draining in relation to the tillering of grasses?
When the subsoil consists of a thin layer of clay on a sandy bed, what use may be made of the sub-soil plow?
The retention of atmospheric manures is more fully ensured by the better exposure of the clayey portions of the soil.
Those manures which are artificially applied, by being plowed under to greater depths, are less liable to evaporation, as, from the greater amount of soil above them, their escape will more probably be arrested; and, from the greater prevalence of roots, they are more liable to be taken up by plants.
The subsoil often contains matters which are deficient in the surface-soil. By the use of the sub-soil plow, they are rendered available.
Sub-soiling is similar to under-draining in continuing the tillering of grasses, and in getting rid of the poisonous excrementitious matter of plants.
When the subsoil is a thin layer of clay on a sandy bed (as in some plants of Cumberland Co. Maine), the sub-soil plow, by passing through it, opens a passage for water, and often affords a sufficient drainage.
To how great a depth will the roots of plants usually occupy the soil?
What is the object of loosening the soil?
How are these various effects better produced in deep than in shallow soils?
If plants will grow better on a soil six inches deep than on one of three inches, there is no reason why they should not be benefited in proportion, by disturbing the soil to the whole depth to which roots will travel—which is usually more than two feet. The minute rootlets of corn and most other plants, will, if allowed by cultivation, occupy the soil to the depth or thirty-four inches, having a fibre in nearly every cubic inch of the soil for the whole distance. There are very few cultivated plants whose roots would not travel to a depth of thirty inches or more. Even the onion sends its roots to the depth of eighteen inches when the soil is well cultivated.
The object of loosening the soil is to admit roots to a sufficient depth to hold the plant in its position—to obtain the nutriment necessary to its growth—to receive moisture from the lower portions of the soil—and, if it be a bulb, tuber, or tap, to assume the form requisite for its largest development.
It must be evident that roots, penetrating the soil to a depth of two feet, anchor the plant with greater stability than those which are spread more thinly near the surface.
The roots of plants traversing the soil to such great distances, and being located in nearly every part, absorb mineral and other food, in solution in water, only through the spongioles at their ends. Consequently, by having these ends in every part of the soil, it is all brought under contribution, and the amount supplied is greater, while the demand on any particular part may be less than when the whole requirements of plants have to be supplied from a depth of a few inches.
May garden soils be profitably imitated in field culture?
The ability of roots, to assume a natural shape in the soil, and grow to their largest sizes, must depend on the condition of the soil. If it is finely pulverized to the whole depth to which they ought to go, they will be fully developed; while, if the soil be too hard for penetration, they will be deformed or small. Thus a carrot may grow to the length of two and a half feet, and be of perfect shape, while, if it meet in its course at a depth of eight or ten inches a cold, hard subsoil, its growth must be arrested, or its form injured.
Roots are turned aside by a hard sub-soil, as they would be if received by the surface of a plate of glass.
Add to this the fact that cold, impenetrable subsoils are chemically uncongenial to vegetation, and we have sufficient evidence of the importance, and in many cases the absolute necessity of sub-soiling and under-draining.
It is unnecessary to urge the fact that a garden soil of two feet is more productive than a field soil of six inches; and it is certain that proper attention to these two modes of cultivation will in a majority of cases make a garden of the field—more than doubling its value in ease of working, increased produce, certain security against drought, and more even distribution of the demands on the soil—while the outlay will be immediately repaid by an increase of crops.
Is the use of the sub-soil plow increasing?
Will its use ever injure crops?
The subsoil will be much improved in its character the first year, and a continual advancement renders it in time equal to the original surface-soil, and extending to a depth of two feet or more.
The sub-soil plow is coming rapidly into use. There are now in New Jersey more foundries casting sub-soil plows than there were sub-soil plows in the State six years ago. The implement has there, as well as in many other places, ceased to be a curiosity; and the man who now objects to its use, is classed with him who shells his corn on a shovel over a half-bushel, instead of employing an improved machine, which will enable him to do more in a day than he can do in the "good old way" in a week.
Had we space, we might give many instances of the success of sub-soiling, but the agricultural papers of the present day (at least one of which every farmer should take) have so repeatedly published its advantages, that we will not do so.
In no case will its use be found any thing but satisfactory, except in occasional instances where there is some chemical difficulty in the subsoil, which an analysis will tell us how to overcome.
As was before stated, its use on wet lands is not advisable until they have been under-drained, as excess of water prevents its effects from being permanent.
CHAPTER V
PLOWING AND OTHER MODES OF PULVERIZING THE SOILMay the satisfaction attending labor be increased by an understanding of the natural laws which regulate our operations?
On what depends the kind of plow to be used?
The advantages of pulverizing the soil, and the reasons why it is necessary, are now too well known to need remark. Few farmers, when they plow, dig, or harrow, are enabled to give substantial reasons for so doing. If they will reflect on what has been said in the previous chapters, concerning the supply of mineral food to the plant by the soil, and the effect of air and moisture about roots, they will find more satisfaction in their labor than it can afford when applied without thought.
PLOWINGWhat is a general rule with regard to this?
Should deep plowing be immediately adopted? Why?
Why is this course of treatment advisable for garden culture?
The kind of plow used in cultivating the surface-soil must be decided by the kind of soil. This question the practical, observing farmer will be able to solve.
As a general rule, it may be stated that the plow which runs the deepest, with the same amount of force, is the best.
We might enter more fully into this matter but for want of space.
The advantages of deep plowing cannot be too strongly urged.
The statement that the deeper and the finer the soil is rendered, the more productive it will become, is in every respect true, and which no single instance will contradict.
It must not be inferred from this, that we would advise a farmer, who has always plowed his soil to the depth of only six inches, to double the depth at once. Such a practice in some soils would be highly injurious, as it would completely bury the more fertile and better cultivated soil, and bring to the top one which contains no organic matter, and has never been subject to atmospheric influences. This would, perhaps, be so little fitted for vegetation that it would scarcely sustain plants until their roots could reach the more fertile parts below. Such treatment of the soil (turning it upside down) is excellent in garden culture, where the great amount of manures applied is sufficient to overcome the temporary barrenness of the soil, but it is not to be recommended for all field cultivation, where much less manure is employed.
How should field plowing be conducted?
How does such treatment affect soils previously limed?
How may it sometimes improve sandy or clay soils?
The course to be pursued in such cases is to plow one inch deeper each year. By this means the soil maybe gradually deepened to any desired extent. The amount of uncongenial soil which will thus be brought up, is slight, and will not interfere at all with the fertility of the soil, while the elevated portion will become, in one year, so altered by exposure, that it will equal the rest of the soil in fertility.
Often where lime has been used in excess, it has sunk to the subsoil, where it remains inactive. The slight deepening of the surface plowing would mix this lime with the surface-soil, and render it again useful.
When the soil is light and sandy, resting on a heavy clay subsoil, or clay on sand, the bringing up of the mass from below will improve the texture of the soil.
As an instance of the success of deep plowing, we call to mind the case of a farmer in New Jersey, who had a field which had yielded about twenty-five bushels of corn per acre. It had been cultivated at ordinary depths. After laying it out in eight step lands (24 feet), he plowed it at all depths from five to ten inches, on the different lands, and sowed oats evenly over the whole field. The crop on the five inch soil was very poor, on the six inch rather better, on the seven inch better still, and on the ten inch soil it was as fine as ever grew in New Jersey; it had stiff straw and broad leaves, while the grain was also much better than on the remainder of the field.
What kind of soils are benefited by fall plowing?
There is an old anecdote of a man who died, leaving his sons with the information that he had buried a pot of gold for them, somewhere on the farm. They commenced digging for the gold, and dug over the whole farm to a great depth without finding the gold. The digging, however, so enriched the soil that they were fully compensated for their disappointment, and became wealthy from the increased produce of their farm.
Farmers will find, on experiment, that they have gold buried in their soil, if they will but dig deep enough to obtain it. The law gives a man the ownership of the soil for an indefinite distance from the surface, but few seem to realize that there is another farm below the one they are cultivating, which is quite as valuable as the one on the surface, if it were but properly worked.
Fall plowing, especially for heavy lands, is a very good means of securing the action of the frosts of winter to pulverize the soil. If it be a stiff clay, it may be well to throw the soil up into ridges (by ridging and back furrowing), so as to expose the largest possible amount of surface to the freezing and thawing of winter. Sandy soils should not be plowed in the fall, as it renders them too light.
DIGGING MACHINESWhat is the digging machine?
A recent invention has been made in England, known as the digging machine or rotary spade, which—although from having too much gearing between the power and the part performing the labor, it is not adapted to general use—has given such promise of future success, that Mr. Mechi (an agricultural writer of the highest standing) has said that "the plow is doomed." This can hardly be true, for the varied uses to which it may be applied, will guarantee its continuance in the favor of the farmer.
Already, in this country, Messrs. Gibbs & Mapes, have invented a digging machine of very simple construction, which seems calculated to serve an excellent purpose, even in the hands of the farmer of limited means.
Its friends assert that, with one pair of oxen, it will dig perfectly three feet wide, and for a depth of fifteen inches. An experiment with an unperfected machine, in the presence of the writer, seemed to justify their hopes.
This machine thoroughly pulverizes the soil to a considerable depth, and for smooth land must prove far superior to the plow.
THE HARROW AND CULTIVATORWhy is the harrow a defective implement?
Why is the cultivator superior to the harrow?
The harrow, an implement largely used in all parts of the world, to pulverize the soil, and break clods, has become so firmly rooted in the affections of farmers, that it must be a very long time before they can be convinced that it is not the best implement for the use to which it is devoted. It is true that it pulverizes the soil for a depth of two or three inches, and thus much improves its appearance, benefiting it, without doubt, for the earliest stages of the growth of plants. Its action, however, is very defective, because, from the wedge shape of its teeth, it continually acts to pack the soil; thus—although favorable for the germination of the seed—it is not calculated to benefit the plant during the later stages of its growth, when the roots require the soil to be pulverized to a considerable depth.
The cultivator may be considered an improved harrow. The principal difference between them being, that while the teeth of the harrow are pointed at the lower end, those of the cultivator are shaped like a small double plow, being large at the bottom and growing smaller towards the top. They lift the earth up, instead of pressing it downwards, thus loosening instead of compacting the soil.