09.04.2018 Views

Horticulture Principles and Practices

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Overhead Sprinkler Irrigation<br />

Water is usually moved under high pressure through a simple or more elaborate network<br />

of pipes. For home gardens <strong>and</strong> l<strong>and</strong>scapes, the pressure used is from the municipal water<br />

source. Municipal water is delivered at very high pressure (more than 80 psi), which can<br />

damage equipment unless it is reduced by installing pressure-reducing valves. A network<br />

of pipes is installed underground <strong>and</strong> fitted with pop-up sprinkler heads to deliver a spray<br />

of water to the area.<br />

Some overhead irrigation systems are designed to be mobile. They are used temporaily<br />

in a location <strong>and</strong> then moved to another area or removed for storage. It may be<br />

as simple as a garden hose sprinkler. There are different designs of this kind of sprinkler,<br />

which is easy to use <strong>and</strong> adapted to irrigating lawns, vegetable gardens, <strong>and</strong> flower beds.<br />

Their use is limited by the length of the hose to which the sprinkler is attached. For irrigating<br />

a large area, a drum-mounted hose (Figure 4–16) may be used. A disadvantage of<br />

this system is that it must be set up for use <strong>and</strong> then removed afterward or moved<br />

periodically until the area is completely irrigated. Certain models allow the sprinkler to<br />

move (moving sprinklers) automatically across the l<strong>and</strong>scape, thus eliminating the need<br />

for human intervention. A perforated hose (porous hose) may also be used to distribute<br />

water to plants in the l<strong>and</strong>scape.<br />

Watering Cans are used for watering flower beds in the absence of sprinkler systems.<br />

Sprinkler irrigation is a method of mimicking the rain by supplying moisture from<br />

above. The equipment may be as simple as a lawn or garden sprinkler or as elaborate as a<br />

large, self-propelled center pivot system used on large commercial farms (Figure 4-16).<br />

The sprinkler system may consist of portable or fixed pipes. Water is distributed through<br />

a network of pipelines under high pressure. Equipment costs can be high. Sprinklers are<br />

desirable where soils have high infiltration rates or uneven surfaces. Sprinklers are also<br />

used where irrigation is not the primary source of moisture for crop growth. In this case,<br />

a portable system may be transported to the area when needed. Center pivot systems that<br />

are equipped with LEPA heads have high water application efficiency <strong>and</strong> also multiple<br />

modes of operation (bubble, sprays, chemigation).<br />

(a)<br />

(b)<br />

(c)<br />

FIGURE 4–16 (a) A center pivot irrigation system. (b) Common lawn oscillating sprinkler. (c) Portable pipes sprinkler system.<br />

(Source: For (a) <strong>and</strong> (c) USDA, (b) George Acquaah)<br />

4.8 Soil Water 133

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!