Sprinkler irrigation

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Sprinklers are often used when flood or furrow irrigation is impractical. Sprinkler can have some advantages over other irrigation methods; for example, through nozzle size selection, sprinklers are adaptable to high or low soil permeabilities. Through uniform wetting of the surface area, seed germination is more uniform; less total water may be used, and sprinklers are effective in washing salts away from salt-sensitive crops. Additionally, the surface need not be level; a properly designed system offers a method of adequately and accurately applying water, even on sloping land with grades up to 3 percent. Sprinklers are sometimes also used for frost control.

In some situations, sprinkler systems may require less labor, whereas with systems that are highly portable, more labor may be used. In general, equipment and energy costs are higher than with flood or furrow methods.

There are different types of sprinklers, each with certain advantages

The hand set was the first type of sprinkler system developed. The main lines are either buried or portable. This system is used on many crops, and is particularly useful for germinating small-seed crops, especially if the seedbed is rough.

The permanent set type has all lines buried below the surface. In some systems the lines are suspended above the surface. Because of the high investment cost, his type of system is usually restricted to orchards, vineyards, high-value crops, or recreation facilities.

The wheel line system was designed to reduce labor by moving pipe across the field with a small gasoline engine in stead of by hand. The lateral that carries the water is mounted on wheels spaced about 6 m (20ft) apart. The lateral pipe, which also acts as the axle, is long, up to 300 meters (985 ft) in length. The sprinklers are mounted in the lateral pipe and another set is often dragged behind the line. To move to the next position, the gasoline engine turns the axle and propels the entire line across the field, saving labor and time. Under windy conditions, application uniformity is poor.

The center pivot system is another labor-saving variation of sprinkler irrigation. The system is used more often in areas where land values are low or the availability of labor low. The line, mounted on wheels driven by water pressure or electric motors, follows a circular path, pivoting around a fixed central point. One disadvantage of the system is that the circular irrigation pattern leaves the concerns in rectangular fields unirrigated.

The hose drag system is another variation for moving the sprinkler line mechanically. A factor attached to one end of the flexible line drags it form place to place. This system mainly used in orchards.