Environmental Engineering Reference
In-Depth Information
Subsurface and surface irrigation
In subsurface irrigation, water is supplied from beneath the soil surface
directly to the roots. Perforated plastic tubes called drip lines are most
commonly used in this type of irrigation. Such systems make very effi-
cient use of water, but over a period of time the small openings in the drip
lines tend to clog with debris, calcium deposits or slime. Subsurface
irrigation is most often used on sod farms, where turf-grass is stripped
several times a year and drip lines can easily be serviced or replaced.
In surface irrigation, water usually originates from irrigation ditches
and flows across the turf-grass area as a result of gravity and the natural
slope. It is advisable only for small areas where water is plentiful and
inexpensive.
Irrigation Systems
Portable irrigation systems
Portable irrigation systems are those that can be moved from one turf
area to another. They are used on many turfs, especially relatively small
ones, but cannot be considered as efficient as installed systems. Portable
systems usually consist of above-ground sprinkler heads attached to
flexible and portable hoses.
Installed irrigation systems
Installed irrigation systems are those in which the system that delivers
water to the sprinkler heads is fixed in place, usually underground.
Besides sprinkler heads, they include pipes, control systems, valves
and, if the system is independent, water pumps. Piping is the basis of a
turf-grass irrigation system. Pipes transport water from the water source
to the sprinkler head where it is dispersed onto the turf. Proper function
of an irrigation system therefore depends on the type, size and condition
of pipes. Pipes can be metal, but today nearly all pipes used for irrigation
are plastic. They are sufficiently strong, lightweight, relatively inexpen-
sive and resistant to corrosion and rust.
A control system coordinates operation of the entire irrigation sys-
tem. In manual systems, someone must turn the control valves by hand.
An automated system typically includes controllers, which integrate a
clock, a timer, and a series of terminals called stations. A programmable
controller allows the turf manager to specify the times and locations at
which turf will be irrigated. A signal from the controller activates each
