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 gra.s.ses 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 gra.s.s 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 cla.s.s 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 a.s.sumes 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 a.s.sumes 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 a.s.sisted 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 a.s.sistance of the sun, wind, etc., a large quant.i.ty 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 pa.s.s 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 33-1/3 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.