The Elements of Agriculture A Book for Young Farmers, with Questions Prepared for the Use of Schools, George E. Waring [read aloud books TXT] 📗

CHAPTER II (UNDER-DRAINING) Pg 194

 

It is about one half or three quarters of an inch thick, and is so porous that water passes directly through it. It has a flat bottom on which to stand, and this enables it to retain its position, while making the drain, better than would be done by the round pipe. The orifice through which the water passes is egg-shaped, having its smallest curve at the bottom. This shape is the one most easily kept clear, as any particles of dirt which get into the drain must fall immediately to the point where even the smallest stream of water runs, and are thus removed. An orifice of about two inches is sufficient for the smaller drains, while the main drains require larger tiles.

These tiles are laid, so that their ends will touch each other, on the bottoms of the trenches, and are kept in position by having the earth tightly packed around them. Care must be taken that no space is left between the ends of the tiles, as dirt would be liable to get in and choke the drain. It is advisable to place a sod--grass side down--over each joint, before filling the trench, as this more effectually protects them against the entrance of dirt. There is no danger of keeping the water out by this operation, as it will readily pass through any part of the tiles.

In digging the trenches it is not necessary (except in very stony ground) to dig out a place wide enough for a man to stand in, as there are tools made expressly for the purpose, by which a trench may be dug six or seven inches wide, and to any required depth. One set of these implements consists of a long narrow spade and a hoe to correspond, such as are represented in the accompanying figure.

SECTION 4 (MECHANICAL CULTIVATION) CHAPTER II (UNDER-DRAINING) Pg 195

 

[Illustration: Fig. 5.

Upton tool.

Spade and hoe.]

With these tools, and a long light crowbar, for hard soils, trenches may be dug much more cheaply than with the common spade and pickaxe. Where there are large boulders in the soil, these draining tools may dig under them so that they will not have to be removed.

When the trenches are dug to a sufficient depth, the bottoms must be made perfectly smooth, with the required descent (from six inches to a few feet in one hundred feet). Then the tiles may be laid in, so that their ends will correspond, be packed down, and the trenches filled up. Such a drain, if properly constructed, may last for ages. Unlike the stone drain, it is not liable to be frequented by rats, nor choked up by the soil working into it.

The position of the tile may be best represented by a figure, also the mode of constructing stone drains.

[Why are small stones better than large stones in the construction of drains?

On what must the depth of under-drains depend?]

It will be seen that the tile drain is made with much less labor than the stone drain, as it requires less digging, while the breaking up of the stone for the stone drain will be nearly, or quite as expensive as the tiles.

SECTION 4 (MECHANICAL CULTIVATION) CHAPTER II (UNDER-DRAINING) Pg 196

 

Drains made with large stones are not nearly so good as with small ones, because they are more liable to be choked up by animals working in them.[AK]

[Illustration: Fig. 6.

a--Tile drain trench. b--Stone drain trench. c--Sod laid on the stone.]

[Describe the principle which regulates these relative depths and distances. (Blackboard.)

Which is usually the cheaper plan of constructing drains?]

The depth of the drains must depend on the distances at which they are placed. If but twenty feet apart, they need be but three feet deep; while, if they are eighty feet apart, they must be five feet deep, to produce the same effect. The reason for this is, that the water in the drained soil is not level, but is higher midway between the drains, than at any other point. It is necessary that this highest point should be sufficiently far from the surface not to interfere with the roots of plants, consequently, as the water line between two drains is curved, the most distant drains must be the deepest. This will be understood by referring to the following diagram.

[Illustration: Fig. 7.

aa--5 feet drains, 80 ft. apart. bb--3 feet drains, 20 ft. apart.]

The curved line represents the position of the water.

In most soils it will be easier to dig one trench five feet deep, than four trenches three feet deep, and the deep trenches will be equally beneficial; but where the soil is very hard below a depth of three feet, the shallow trenches will be the cheapest, and in such soils they will often be better, as the hard mass might not allow the water to pass down to enter the deeper drains.

By following out these instructions, land may be cheaply, thoroughly, and permanently drained.

FOOTNOTES Pg 197

[AK] It is probable that a composition of hydraulic cement and some soluble material will be invented, by which a continuous pipe may be laid in the bottoms of trenches, becoming porous as the soluble material is removed by water.

SECTION 4 (MECHANICAL CULTIVATION) CHAPTER III (ADVANTAGES OF UNDER-DRAINING) Pg 197

The advantages of under-draining are many and important.

It entirely prevents drought. It furnishes an increased supply of atmospheric fertilizers. It warms the lower portions of the soil. It hastens the decomposition of roots and other organic matter. It accelerates the disintegration of the mineral matters in the soil. It causes a more even distribution of nutritious matters among those parts of soil traversed by roots. It improves the mechanical texture of the soil. It causes the poisonous excrementitious matter of plants to be carried out of the reach of their roots. It prevents grasses from running out. It enables us to deepen the surface soil.

By removing excess of water--

It renders soils earlier in the spring. It prevents the throwing out of grain in winter. It allows us to work sooner after rains. It keeps off the effects of cold weather longer in the fall. It prevents the formation of acetic and other organic acids, which induce the growth of sorrel and similar weeds. It hastens the decay of vegetable matter, and the finer comminution of the earthy parts of the soil. It prevents, in a great measure, the evaporation of water, and the consequent abstraction of heat from the soil. 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.

 

SECTION 4 (MECHANICAL CULTIVATION) CHAPTER III (ADVANTAGES OF UNDER-DRAINING) Pg 198

 

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?]

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.