Improving Farm Lands

Sun (Auckland), Volume 1, Issue 86, 2 July 1927, Page 26

Improving Farm Lands

Need for Draining

Aiding Production

WELL-DRAINED soil when workable has considerably more available moisture than undrained soil in the same condition. In addition it is considerably warmer and is work, able several weeks earlier in tfte season. Thus the farmer is enabled to get a better start with his crops and is given a better chance for big returns. Few parts of New Zealand are to be found where drainage systems could not be inaugurated to advantage. The liigh initial cost, certainly, stands in the way but, undoubtedly, more attention could be paid to this important part o.f soil management.

iLL soil contains some moisture. -LjL whether it appears so or not. This water may be of two kinds, either hydrostatic (ground water) or capillary moisture. The latter fills the small pores between the particles of soil above the ground water level. The former fills all the spaces, big or little, below that level. The ground water level is, of course, constantly shifting as the seasons are wet or dry. It is that level at which water stands in a hole. For crops to thrive and prosper the ground level must be several feet below the surface and capillary action, as exerted by any porous body such as a lump of sugar or a sponge is depended upon to suck up from the ground water sufficient moisture for the use of the plants. REASONS FOR DRAINAGE

The reasons for drainage are many, but all contributary to the one great reason, the raising of a better crop. In many cases crops have been more than

doubled on land which, though tillable before, has been damp and cold at certain seasons of the year. Drainage opens up the soil by removing surplus water and allowing the air to enter and circulate all through the porous soil layers, making the ground more pliable and less likely to cake. It assists the necessary chemical actions in the soil and promotes the growth of bacteria which are necessary in order that soil materials may be developed into plant food. Air is also essential to rugged root growth. If the ground is water-soaked so that the roots are compelled to cling to the surface to breathe, then in times of drought the water level goes so far below them that capillary action cannot raise the moisture high enough for their use. if, on the other hand, the upper soil contains free air, the roots strike deep down and the comparatively little change in the water level during the course of a drought does not affect them. They have a larger area of capillary tubes to draw up their water supply. Well-drained soils are more open and less compact and therefore hold more water in suspension than undrained soils. They have a greater capillary power for the very reason that they are porous, so that long after crops in undrained soils have perished, those tiny capillary tubes in the porous soil supply water to their plants.

UNDER-DRAINAGE Two main methods or drainage **, offered the farmer, surface with ditches, or under-drainage. a ? complished preferably bv the use * the modern tile drains. Of these, tl’ latter is to be recommended. In aiding the passage of air through the it helps the chemical and bacteru; actions which occur. Fertility is added to the soil with each fall of rai for. as the rain is drawn down the soil, it is deprived of the nitrog* and carbon which it took from the air in passing. This is all lost if the water is carried away by the surface flo* Manure and other fertilisers are drawdown through the soil layers by uwater and surface washing is vented. FOUR MAIN SYSTEMS Four main systems of tile drains are recommended —the natural systen the gridiron, the single line and th?

herringbone. In the natural system single lines of tiles are laid along the lowest part of the wet marshes, no attempt being made to lay out a rystematic design. It is in many ways the most economical and frequently the most efficient. The gridiron system is used in flat fields requiring thorough covering, and is very economical. The herringbone is rather a cross between the former two. It is used in broad fields with a depression along which the main is placed. It is not so economical as the gridiron plan, but is necessary in some places. The single lire is used for inexpensive first cost systems. In every case tile main should run along the lowest ground and the laterals run parallel with each other and with the slope, unless the latte: is very steep. It is thus seen that the field will to some extent lay itself out and choose its own system. The profits of draining depend largely upon the skill and economy used in planning and executing the work. Seldom will the first crop pa; the cost of the installation of the drainage, but seldom where the requisite attention has been paid to economy has draining not more than paid for the labour and expense involved. Not only has it increased the crop, but it has made it earlier and thus of more value. —R- C.