BENEFITS OF DRAINAGE.

King Country Chronicle, Volume VI, Issue 436, 3 February 1912, Page 6

BENEFITS OF DRAINAGE.

One of the most obvious results of drainage, from which all others benefit saccrue, is the removal of surplus water. Plants require a moist soil, but cannot grow in a saturated soil where the roots come in contact with standing water below the water table, says C. P. Nofgord in an Arkansas Bulletin. Plants obtain their moisture almost entirely from capillary water; that is, the water which is held in the small openings between soil grains as oil in a wick. Since capillary water is only available in the unsatured soil above the water table, drainage, by lowering the water table makes room for more capillary water, thus increasing the supply of water available tc plant roots, and making possible the storage of large quantities of moisture during a wet season against the time of droughts. With draiange comes also the more favourable condition for the formation of mulches and consequent prevention of waste of moisture by surface evaporation. By the downward percolation of water toward the drains, the plant food, of the fine surface soil and the manures, is carrried downward to become thoroughly incoporated in the soil, rarther than to be washed away by surface overflow. Moreover, the deepening of the soil increases its capacity for water, and prevents the overflow which washes away the saturated muddy top soil. Vegetation can use only plant food of finely-powdered soil easily soluble in water. The passages of air and heat into and through the soli, made possible by the removal of the standing water and the interchange of air through the soil between the bodies of air in the tile and the air above the soil, disintegrates the soil particles hitherto unavailable to plants, and produces that fine, crumbling, workable condition of the soil, known as fine texture, in which is found the maximum amount of soluble plant food and the most favourable conditions for plant growth. The toughest clay soils are in this way made friable, responding with increased crops. The increase of heat and air porvide favourable conditions for the increase in the numbers and activity of bacteria, the minute plants whose function it is to set free plant food and change the form of the constituents of soil into a food for plants. Moreover, the constant passage of surface water into soilc arries in chemicals which act vigorously to set free plant food bound in various chemical combinations. Since it is very difficult to heat water from above, a water coaked soil is very slow to become arm in the

spring; but vveli drained soil, like a metal, is easily and quickly heated in the spring, hence is an early soil. The groth and extensions of root systems as instruments for obtaining nourishment for the later growth of the upper part of the piant must take place during a certain definite period previous to top development. This period and consequent root development is shortened by a cold, late plant bed in the spring, but increased by a warm, early soil, hence ihe removal of water by drainage, by permitting an early rapid heating of the soil, insures a vigorous root system to supply abundant nourishment later for the growth of the top. The development of the root systems is further helped by the lowering of the water table. Lowering the water table permits a deeper root development and consequently more root surface.