CHAPTER III.
ADVANTAGES OF UNDER-DRAINING.
The advantages of under-draining are many and important.
1. It entirely prevents drought.
2. It furnishes an increased supply of atmospheric fertilizers.
3. It warms the lower portions of the soil.
4. It hastens the decomposition of roots and other organic matter.
5. It accelerates the disintegration of the mineral matters in the soil.
6. It causes a more even distribution of nutritious matters among those parts of soil traversed by roots.
7. It improves the mechanical texture of the soil.
8. It causes the poisonous excrementitious matter of plants to be carried out of the reach of their roots.
9. It prevents grasses from running out.
10. It enables us to deepen the surface soil.
By removing excess of water—
11. It renders soils earlier in the spring.
12. It prevents the throwing out of grain in winter.
13. It allows us to work sooner after rains.
14. It keeps off the effects of cold weather longer in the fall.
15. It prevents the formation of acetic and other organic acids, which induce the growth of sorrel and similar weeds.
16. It hastens the decay of vegetable matter, and the finer comminution of the earthy parts of the soil.
17. It prevents, in a great measure, the evaporation of water, and the consequent abstraction of heat from the soil.
18. It admits fresh quantities of water from rains, etc., which are always more or less imbued with the fertilizing gases of the atmosphere, to be deposited among the absorbent parts of soil, and given up to the necessities of plants.
19. It prevents the formation of so hard a crust on the surface of the soil as is customary on heavy lands.
How does under-draining prevent drought?
1. Under-draining prevents drought, because it gives a better circulation of air in the soil; (it does so by making it more open). There is always the same amount of water in and about the surface of the earth. In winter, there is more in the soil than in summer, while in summer, that which has been dried out of the soil exists in the atmosphere in the form of a vapor. It is held in the vapory form by heat, which acts as braces to keep it distended. When vapor comes in contact with substances sufficiently colder than itself, it gives up its heat—thus losing its braces—contracts, and becomes liquid water.
This may be observed in hundreds of common operations.
Why is there less water in the soil in summer than in winter, and where does it exist?
What holds it in its vapory form?
How is it affected by cold substances?
Describe the deposit of moisture on the outside of a pitcher in summer.
What other instances of the same action can be named?
It is well known that a cold pitcher in summer robs the vapor in the atmosphere of its heat, and causes it to be deposited on its own surface. It looks as though the pitcher were sweating, but the water all comes from the atmosphere, not, of course, through the sides of the pitcher.
If we breathe on a knife-blade, it condenses in the same manner the moisture of the breath, and becomes covered with a film of water.
Stone houses are damp in summer, because the inner surfaces of the walls, being cooler than the atmosphere, cause its moisture to be deposited in the manner described. By leaving a space, however, between the walls and the plaster, this moisture is prevented from being troublesome.
How does this principle affect the soil?
Explain the experiment with the two boxes of soil.
Nearly every night in the summer season, the cold earth receives moisture from the atmosphere in the form of dew.
A cabbage, which at night is very cold, condenses water to the amount of a gill or more.
The same operation takes place in the soil. When the air is allowed to circulate among its lower and cooler particles, they receive moisture from the same process of condensation. Therefore, when, by the aid of under-drains, the lower soil becomes sufficiently open to admit of a circulation of air, the deposit of atmospheric moisture will keep the soil supplied with water at a point easily accessible to the roots of plants.
If we wish to satisfy ourselves that this is practically correct, we have only to prepare two boxes of finely pulverized soil, one, five or six inches deep, and the other fifteen or twenty inches deep, and place them in the sun at mid-day in summer. The thinner soil will be completely dried, while the deeper one, though it may have been perfectly dry at first, will soon accumulate a large amount of water on those particles which, being lower and more sheltered from the sun's heat than the particles of the thin soil, are made cooler.
With an open condition of subsoil, then, such as may be secured by under-draining, we entirely overcome drought.
How does under-draining supply to the soil an increased amount of atmospheric fertilizers?
How does it warm the lower parts of the soil?
2. Under-draining furnishes an increased supply of atmospheric fertilizers, because it secures a change of air in the soil. This change is produced whenever the soil becomes filled with water, and then dried; when the air above the earth is in rapid motion, and when the comparative temperature of the upper and lower soils changes. It causes new quantities of the ammonia and carbonic acid which it contains to be presented to the absorbent parts of the soil.
3. Under-draining warms the lower parts of the soil, because the deposit of moisture (1) is necessarily accompanied by an abstraction of heat from the atmospheric vapor, and because heat is withdrawn from the whole amount of air circulating through the cooler soil.
When rain falls on the parched surface soil, it robs it of a portion of its heat, which is carried down to equalize the temperature for the whole depth. The heat of the rain-water itself is given up to the soil, leaving the water from one to ten degrees cooler, when it passes out of the drains, than when received by the earth.
There is always a current of air passing from the lower to the upper end of a well constructed drain; and this air is always cooler in warm weather, when it issues from, than when it enters the drain. Its lost heat is imparted to the soil.
How does it hasten the decomposition of roots and other organic matter in the soil?
How does it accelerate the disintegration of its mineral parts?
Why is this disintegration necessary to fertility?
This heating of the lower soil renders it more favorable to vegetation, partially by expanding the spongioles at the end of the roots, thus enabling them to absorb larger quantities of nutritious matters.
4. Under-draining hastens the decomposition of roots and other organic matters in the soil, by admitting increased quantities of air, thus supplying oxygen, which is as essential in decay as it is in combustion. It also allows the resultant gases of decomposition to pass away, leaving the air around the decaying substances in a condition to continue the process.
This organic decay, besides its other benefits, produces an amount of heat perfectly perceptible to the smaller roots of plants, though not so to us.
5. Draining accelerates the disintegration of the mineral matters in the soil, by admitting water and oxygen to keep up the process. This disintegration is necessary to fertility, because the roots of plants can feed only on matters dissolved from surfaces; and the more finely we pulverize the soil, the more surface we expose. For instance, the interior of a stone can furnish no food for plants; while, if it were finely crushed, it might make a fertile soil.
Any thing, tending to open the soil to exposure, facilitates the disintegration of its particles, and thereby increases its fertility.
How does under-draining equalize the distribution of the fertilizing parts of the soil?
Why does this distribution lessen the impoverishment of the soil?
How does under-draining improve the mechanical texture of the soil?
How do drains affect the excrementitious matter of plants?
6. Draining causes a more even distribution of nutritious matters among those parts of soil traversed by roots, because it increases the ease with which water travels around, descending by its own weight, moving sideways by a desire to find its level, or carried upward by attraction to supply the evaporation at the surface. By this continued motion of the water, soluble matter of one part of the soil may be carried to some other part; and another constituent from this latter position may be carried back to the former. Thus the food of vegetables is continually circulating around among their roots, ready for absorption at any point where it is needed, while the more open character of the soil enables roots to occupy larger portions, making a more even drain on the whole, and preventing the undue impoverishment of any part.
7. Under-drains improve the mechanical texture of the soil; because, by the decomposition of its parts, as previously described (4 and 5), it is rendered of a character to be more easily worked; while smooth round particles, which have a tendency to pack, are roughened by the oxidation of their surfaces, and move less easily among each other.
8. Drains cause the excrementitious matter of plants to be carried out of the reach of their roots. Nearly all plants return to the soil those parts of their food, which are not adapted to their necessities, and usually in a form that is poisonous to plants of the same kind. In an open soil, this matter may be carried by rains to a point where roots cannot reach it, and where it may undergo such changes as will fit it to be again taken up.
Why do they prevent grasses from running out?
9. By under-draining, grasses are prevented from running out, partly by preventing the accumulation of the poisonous excrementitious matter, and partly because these grasses usually consist of tillering plants.
These plants continually reproduce themselves in sprouts from the upper parts of their roots. These sprouts become independent plants, and continue to tiller (thus keeping the land supplied with a full growth), until the roots of the stools (or clumps of tillers), come in contact with an uncongenial part of the soil, when the tillering ceases; the stools become extinct on the death of their plants, and the grasses run out.
The open and healthy condition of soil produced by draining prevents the tillering from being stopped, and thus keeps up a full growth of grass until the nutriment of the soil is exhausted.
10. Draining enables us to deepen the surface-soil, because the admission of air and the decay of roots render the condition of the subsoil such that it may be brought up and mixed with the surface-soil, without injuring its quality.
The second class of advantages of under-draining, arising in the removal of the excess of water in the soil, are quite as important as those just described.
How does the removal of water render soils earlier in spring?
Why does it prevent the throwing out of grain in winter?
Why does it enable us to work sooner after rains?
Why does it keep off the effects of cold weather longer in the fall?
11. Soils are, thereby, rendered earlier in spring, because the water, which rendered them cold, heavy, and untillable, is earlier removed, leaving them earlier in a growing condition.
12. The throwing out of grain in winter is prevented, because the water falling on the earth is immediately removed instead of remaining to throw up the soil by freezing, as it always does from the upright position taken by the particles of ice.
13. We are enabled to work sooner after rains, because the water descends, and is immediately removed instead of lying to be taken off by the slow process of evaporation, and sinking through a heavy soil.
14. The effects of cold weather are kept off longer in the fall, because the excess of water is removed, which would produce an unfertile condition on the first appearance of cold weather.
The drains also, from causes already named (3), keep the soil warmer than before being drained, thus actually lengthening the season, by making the soil warm enough for vegetable growth earlier in spring, and later in autumn.
How does it prevent lands from becoming sour?
Why does it hasten the decay of roots, and the comminution of mineral matters?
How does it prevent the abstraction of heat from the soil?
15. Lands are prevented from becoming sour by the formation of acetic acid, etc., because these acids are produced in the soil only when the decomposition of organic matter is arrested by the antiseptic (preserving) powers of water. If the water is removed, the decomposition of the organic matter assumes a healthy form, while the acids already produced are neutralized by atmospheric influences, and the soil is restored from sorrel to a condition in which it is fitted for the growth of more valuable plants.
16. The decay of roots, etc., is allowed to proceed, because the preservative influence of too much water is removed. Wood, leaves, or other vegetable matter kept continually under water, will last for ages; while, if exposed to the action of the weather, as in under-drained soils, they soon decay.
The presence of too much water, by excluding the oxygen of the air, prevents the comminution of matters necessary to fertility.
How much heat does water take up in becoming vapor?
Why does water sprinkled on a floor render it cooler?
Why is not a cubic inch of vapor warmer than a cubic inch of water?
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.