THE RURAL WORLD.

King Country Chronicle, Volume VIII, Issue 641, 7 February 1914, Page 6

THE RURAL WORLD.

EFFECT OF DRAINING ON THE \SOIL. The moat important result is that it makes tl«e soil warmer. A wet soil is cold, chiefly because the water in it is constantly evaporating, and evaporation iB a cooling process. To illustrate this: If the bulb of one thermometer is covered with wet muslin, and the uulb of another similar thermometer is left uncovered, the wet thermometer may rpgißter ns much as 15 degrees cooler when both are swung in dry air. This h due to the cooling effect o£ the evaporation of the water. Moreover, water is a poor conductor of beat; wet soils warm in the sun slowly, because the water they contain holds down the temperature. There is usually a difference of 5 to 10 degrees between drained and undrained soil in the same field. In fact, the temperature of a soil in summer is very largely determined by the amount of water it contains; the wetter it is the colder i«" iB. Warmth is one of the chief essentials for the germination and growth of farm crops; it is the coldness of a poorly drained soil, more than the mere exceßS of water it contains, that is responsible for most of the unsatisfactory growth of crops upon it. Draining a soil allows the air to enter it more freely. If all the species between the soil grains are filled with water air cannot enter. Air is one of the most important agencies that help to make a soil productive. It changes tha rock particles of the soil into plant food and is essential to the decay of plant* in the soil, making humus. Seeds must have air or they will not jerminate. Tbe soil bacteria that make fertility cannot thrive with out air; the more thoroughly and the more deeply a soil can be aerated the richer it should be, and tbe better should plants grow upon it. The depth to whicb air penetrates tbe oil increases whan a water table is loweerd by drainage, hence a larger feeding area is presented to the roots. DRAINING A SOIL MAKES IT MORE MOIST. Although it may seem a paradox, draining a soil may make it more moist at the timeß when moisture is needed most This is a feature of drainage that many people find hard to understand yet explanation is very Bimple. Drainage lowers the water table thus increasing the volume of the soil above it in which the roots of plants can feed, for they can use only film water. The larger the area of soil above the water table the more film water there is for the paints to use. They root deeper and so are farther away from the dry surface soil. Furthermore. a soil is more mellow after being drained than before, so it can absorb and hold more water aa film water moisture, and its ability to draw up water trom the water table is in creased Unaer drainage simply carries off free or standing water, thus leaving more room for the film watnr that plants ÜBe. Hence it is that drained Boil is dryer in a wet time and more moist in a dry time than before it was drained. In humid regions under drainage may be equivalent to irrigation as a means of supplying water to the crop. Tha farmer wbo drainß his 1 and owns more suil than he did before; for until the water table was lowered he had the use only of the soil above it, tbe only part in which the roots of his plants can feed. If he lowers the wat°r table two feet he adds a layer of soil two feet thick to his property. He has two feet more of soil in which the roots of his plants may find nourishment. This is the cheapest way of increasing the size of the farm. After a soil has been drained the roots of plant 3 penetrate it deeper, earthworms burrow deeper in it, air follows these channels and the Ventilation of the soil is still further improved. A system of tile drainage is itself very effective in aerating the soil. Most of the time the tiles carry air, as well as water. When the surface air is much warmet than the soil air, as on a warm day in early spring system of tile drains may supply a alight bottom heat, or at least be the means of equalising temperature. Thus a good system of under drainage aerates the soil both from above and from below. PRACTICAL RESULTS FROM DRAINING LAND. The s practical result jf the better aeratior and increased warmth secured by draining land is that the soil becomes richer and more productive. Not only does more plant food in the soil become available, but also the manures or fertilisers that may be applied are more effective, since they too must first be treated with nature's chemicals beforp the plants can use them. The beneficial bacteria of the soil which thrive only in warmth and moisture —not wetness are encouraged to multipl®. The season is lengthened at both ends the soil can be worked earlier and later, so crops have the use of it longer. If a poorly drained field is sloping there may be a considerable loss of fretility by surface washing. After this field is drained, rain sinks into the soil more readily, as it is looser -'and dryer, and so a large part of the surfacewashing is checked. The cost of growing a crop is reduced, especially in preparing the seed bed, for a mellow, well drained soil is easier to handle, and can be brought into the right shape quicker than cloddy, poorly drained soil. Seeds germinate better, because the soil is warm and dry instead of old and wet The quality as well as the yield of the crop is often improved. This is particularly true of grass or hay; that which grows in well drained meadows or pastures is of much higher value for feeding than that which rgows in wet land, not only because the better grasses thrive in the well drained but al3o because they actually contain more nutriment. Thsee and other benefits of draining wet, shallow or bard soils may be chryetalised into one sentence: draining increases the producing

capacity of such soils and enables the man who tills them'to put his crops upon the market at a lower cost of production.