Text 10

Irrigation (hydroamelioration)

Irrigation Systems in Cotton, Rice, Vegetable and Fruit-Growing Areas

The purpose of hydromelioration is to create favourable conditions for plant-growing and raise soil fertility in arid regions. Irrigation makes for considerably higher yields in areas where total precipitation is insufficient.

An irrigation system, regularly servicing big areas, con­sists of the following sections:

1. head water intake unit with a regulating installation in the river's bed;

1. irrigation canals (permanent and temporary);

2. distribution system (sometimes also a drainage system);

3. hydrotechnical installations on the canals and network;

4. service and dwelling houses.

Text 11 watering techniquecs and methods

The cutting of canals makes for the regular and correct watering of large areas of land. Three methods of watering have received the widest recognition: gravity-flow surface irrigation, subsoil irrigation and sprin­kling.

Most widespread today is the first method. Gravity-flow surface irrigation is effected in three ways depending on the structure of the soil, on the cultivated crops and requirements of agronomy:

1. furrow irrigation;

1. border flooding;

2. flooding.

Under the furrow method the water from the canals, furrows or pipelines flows in strips over the surface, or is fed into the irrigation furrow. Furrow irrigation is used for all the widespaced-row crops (cotton, maize, potatoes, sugar-beet, etc.).

The border flooding method is used for narrow-row crops (various grasses, grains, etc.). The flooding method is used chiefly for rice-growing and for leaching out saline soils.

Under the subsoil method, the water is fed from pipes or artificial mole-passages running underground. Subsoil irrigation has a great future. It is most effectively used on vine­yards, in berry gardens and vegetable farming.

In sprinkling or overhead irrigation the water is pulverized over the field in the form of artificial rain.

This method has found particularly broad application because of its high degree of mechanization and the possibil­ity of using it on abrupt slopes.

Of course in many cases dry farming can be combined with sprinkling.

Text 12 land reclamation

Great stress has also been laid on land reclamation. There exist different ways of land reclamation.

On marshland drainage is made use of. In result of this crop land and meadow land are reclaimed from what was formerly waste land. The retirement of water is carried out by means of a system of ditches, principally tile ditches (that is ditches faced with tile) and mole drainage (or under­ground drainage).

Combating erosion constitutes the next division of land reclamation. On broken country erosion may be due in the place to gullying (the formation of gullies) which must be closed essentially by planting shrubs or- afforestation, or by level terracing with grass or bushes grown on the level-ter­race ground. This is known as gully detention. To prevent the water of heavy rains from forming new gullies grassed waterways or diversion ditches are foreseen, where the grass prevents washing of soil.

On silt-loam, sandy and other soils, including even black-earth (chernozem), scorching winds blowing away the top­most layer of the soil are a real scourge.

To fight the carrying away of fine earth as a result of sand-blows, shelter-belts (or windbreaks) constitute the chief means, while rolling the soil is likewise a most useful practice.