Automation in Irrigation Methods

In order to form one kilogram of dry matter, wheat draws out of the soil 300-400 litres of water, maize 200-300 litres and cotton 500-600 litres, with о cotton yield оf 3,5-4,0 tons per hectare, 5,000-6,000 tons of water have to be delivered to every hectare of the plantation during the vegetation period. In those areas of the USSR where cotton is grown, the summer is dry and all the water necessary for the harvest has to be delivered to the fields over а network of artificial canals and ditches. Many large hydrotechnical developments are fitted with devices for mechanizing and automating the gate controls. The operator has but to press а button on the control panel to make the water flow into the take-off canal.

The water that comes to the field must get to the roots of every plant. There are as many as 100,000 cotton shrubs, 3-5 million rice and wheat plants on а hectare of 1and. There aremachines operating on the rain principle. Water is elevated to the height of one or two meters and sprinkled over the plot. Such machines are adequate for supplying fields with small quantities of water – 300-400 cubic renters for every watering.

But what about the arid conditions of the south of the Ukraine, the Caucasus and Central Asia, where 6,000-10,000 cubic meters of water have to be delivered to every hectare of crops? In these conditions the use of sprinkling machines does not always pay.

Many scientists and specia1ists worked hard at the problem of irrigation mechanization. А new system of а combined irrigation network has been developed by scientists.

What is this system like? The combined gravity-head irrigation network consists of permanent underground delivering and watering pipelines and of movable flexible watering hoses. The pipe-lines and hoses are made of polyethylene or similar materia1. The stationary watering pipelines may be made of asbestos cement.

The underground delivering pipelines are laid along the whole length of the plot to be watered. То both sides of the pipe-line, watering pipes and movable watering hoses are provided. On а plot 2,000 meters 1ong and 1,000 meters wide it is sufficient to have two delivering mains spaced 500 meters from each other.

Flexible watering hoses are attached to water hydrants ofthe delivering pipeline. The hoses and underground watering pipelines are perforated, the holes matching the row width. The furrow method of irrigation is the most suitable one for the combined irrigation network.

Water is fed from the canal directly into the underground delivering pipe-lines via the water take-off facilities, Thenecessary head is created in the network by taking advantage of the natura1 slope of the area.

In the elevated part of the plot, where there is no adequate head in the delivering pipe-1ine yet, watering is carried out with the aid of movable flexib1e watering hoses placed on the field surface. In the 1ower part of the plot, it is sufficient to open the gates in the distributing wells to make the water rush into the underground watering pipe-1ines. Flowing out of holes in these pipe-lines, the water finds its way through а 25-30 centimeters layer of soi1, as little springs it flows into the furrows, moistens the soi1 around and reaches the roots of the plants.

The ends ofthe delivering and watering pipelines are fitted with specia1 f1ushing valves which serve to free the pipelines of si1t. When they are opened, the force of the water stream hurls the silt beyond the network.

The characteristic feature of the combined irrigation network is that it distributes water uniformly among the furrows through underground watering pipelines and flexible hoses. А turn of the gate changes the spurt simultaneously in 300-500 furrows within а few minutes. Besides, fertilizers may be supplied to plants together with water. The combined watering system makes it possible to water а 10-15 hectare plot simultaneously. The production of а ton of cotton takes 15-20 per cent less irrigation water than with conventiona1 watering methods.

А stable 15 per cent increment in cotton crop yields has been obtained on plots irrigated by the new system. And, last but not 1east, the soil is made fuller use of due to the removal of the temporary irrigation network and the efficiency of tractors is increased by 20-25 per cent.