Drainage
a process by which wet and unhealthy soils are rendered arable and healthy.
DRAINAGE Benefits of Drainage.-1. Removal of superfluous water. Not only is the standing water at the surface carried off, but the water-table is lowered, increasing the depth of soil.
2. Improves es soil texture. Drained soils are more friable, less lumpy, offer less resistance to plant roots, and are of better texture in every way, than undrained soils. 3. Increases root pasturage. Agricultural literature is full of testimony to the benefits of deep tillage. The deeper the soil is stirred the greater its productiveness.
4. Increases soil fertility. It prevents loss of fertility by water passing over the surface. It adds to the fertility by sending summer showers down through the soil, instead of over them, enabling the crop to use the nitric acid and ammonia brought down. It increases the effect of manures by bringing them more quickly into solution and into more intimate contact with plant roots.
5. Makes tillage easier. Waste land is reduced, and the better texture of soil, its finer tilth and greater friability decrease draft and increase the effectiveness of tillage implements.
6. Lengthens the growing season for crops. Frost comes out earlier in the spring and the land becomes earlier warmed. Evaporation lowers temperature, but drainage removes water without evaporation. 7. Assists disintegration. Frosts penetrate deeper in winter in drained soils, assisting in unlocking the stores of mineral plant food. 8. Favors nitrification and bacterial action. Plants are largely dependent on the soil for their supply of nitrogen. This decomposition of organic matter in the decomposition of nitrogen . This change is brought about by the action of ferments or bacteria which thrive only under certain conditions of temperature and moisture. Drainage supplies the most favorable condition for their development.
9. Prevents heaving. The effect of stool-ice in throwing out young plants in winter is often to diminish seriously and even destroy the crop. Drainage dries up the surface soil and prevents the formation of stool-ice.
10. Lessens washing and diminishes violence of floods. By increasing the absorptive power of the soil less water is left to pass over the surface in a rainy season.
11. Improves the quantity and quality of crops. That the yield of crops is much greater on drained soils hardly needs to be substantiated. Rust, mildew, blight, etc., are much less prevalent in crops on drained soils.
DRAINAGE 12. Diminishes the effect of drought.
By making the season earlier tillage can begin sooner and save moisture from wasting. 13. Healthfulness improved. So well known is this fact that large towns have undertaken the drainage of adjacent swamps to render the region more healthful.
Kinds of Drains. - Cobble-stone or socalled blind drains are undoubtedly the most ancient covered drains ever made.
They are trenches partly filled with boulnearby and covered over with the earth thrown out.
Cobble duct. Two rows of boulders are laid in the bottom of the trench three or four inches apart, a third row is laid between on top, and these are covered with smaller stones and finally covered with the earth thrown out.
Brush drains are made by filling a trench with wide bottom full of brush laid in with stem ends downstream, , covering with sod, leaves or straw, and filling in. They are prone to cave in as the brush settles and decays , and are treacherous to animals.
French brush differ from common brush drains in having stakes driven X-wise in the bottom of the trench to raise the brush a few inches.
Box drains consist of two boards nailed together forming a V, laid in the bottom of trench with the apex up, and covered; or, of three boards , two set on edge three or four inches apart, with the third placed in the trench open side down.
Plug drains are made by means of a plug, five or six feet long, consisting of four or five sections of wood with uniform elliptical cross sections, three or four inches in diameter , linked together by a short chain and bar for drawing the plug along the trench. Beginning at the upper end of the drain the plug is laid chain end downstream, in the bottom of the trench. A few inches of earth over the plug; it is then drawn on by means of bar and chain, two-thirds ered again, etc. chain, two-thirds of its length, and cov- Mole drains are made with a mole plow, an implement constructed to draw an iron plug through the ground about three feet below the surface. This plow is usually drawn by a capstan with horses or oxen on the sweep.
Tile Drainage. - Drain tiles were in use at a very early date, probably during the Roman period.
At first three bricks of common or special shape were used for the conduit, the conduit, consisting of two set up inches apart, with a third across the top. Later a single brick con DRAKE was molded into the shape of the three V-shaped tiles with broad soles on which as above laid.
These were superseded by to admit the water. Plain cylindrical to rest, and perforations along the back tiles are now generally used.
Outlets. One of the weakest parts of a drain is the point of discharge. For this reason it is best not to have a seprather to collect all into a system with a arate outlet for each line of tiles, but single outlet.
Minors or Laterals. The smaller subsidiary lines are so called in distinction from the main drain, which follows the lower part of the field and receives the discharge from the smaller drains. should be carefully studied, surveyed and Before construction, a drainage system mapped out, both for greater accuracy of work and for location of drains afterperfected, which have demonstrated their ward.
Steam-power ditchers have been practicability where land is free from obstructions and the structions and the grade fairly even.