Basins: Water is
ponded on a flat or slightly graded field with bermed boundaries. Water is
introduced onto the field surface in amounts equal to the water requirement
and allowed to infiltrate into the root zone.
Borders: Water
is spread in sheet flow over a field from a head ditch or field ditches in
a controlled flooding situation. Fields are either level or graded with either
ditches or berms separating field units.
Bubbler: An irrigation
system that falls into the trickle category in which water is applied to the
soil surface as a small stream or fountain. Discharge rates are generally
greater than those for drip, but less than 60 gal/hr.
Crown Flooding:
A field with raised beds is flooded up to near the bed crowns. The water is
held for a period of time to allow for infiltration before it is allowed to
drain.
Drip: A category
of trickle irrigation in which water is applied to the soil surface in discrete
or continuous drops, or tiny streams through emitters. The terms drip and
trickle irrigation are often used interchangeably. However, the American Society
of Agricultural Engineers Practice ASAE EP405 makes the distinction that trickle
irrigation includes systems with higher discharge rates than most drip systems.
To be classified as drip irrigation, point source emitters should have discharge
rates less than 3 gal/hr and line source emitters less than 1 gal/hr/ft of
lateral.
Furrows: Gravity is used as the driving force which pushes water down shallow, closely spaced ditches to spread water over a field surface. Fields are generally sloped and open at the bottom end, allowing runoff to occur. This type of system is generally used in heavy soils with deep soil profiles above water tables such that water table control is not a factor in supplying water to the crop root zone.
Seepage: A local
term for subirrigation that depends on water table control to supply crop
water needs from below the root zone.
Spray: An irrigation
method that falls into the trickle category, characterized by the application
of water to the soil surface as a small spray or mist. Discharge rates are
generally less than 30 gal/hr.
Sprinkler: A pressurized
system where water is distributed through pipes to the field and applied through
a variety of outlet sprinkler heads or nozzles. Pressure is used to spread
water droplets above the crop canopy to simulate a rainfall with potentially
ideal intensities and durations for crop needs.
Subirrigation: A
water table control system that uses the raising of the water table to add
water to the root zone. Water is introduced into parallel open ditches and
flows under the root zone through the soil profile to raise the water table
to a level that allows for sufficient wetting of the root zone from the water
table aquifer below. Closely spaced tile, perforated pipe, or mole drains
that run perpendicular to the field ditches are often used to aid in the lateral
spreading of water beneath the root zone.
Subsurface: A low
pressure system that falls into the trickle category with the defining characteristic
being that the laterals, emitters and line source tubes are buried beneath
the soil surface, thereby applying water directly to the root zone. Discharge
rates are of the same magnitude as drip rates.
Trickle: A low pressure system where water is distributed through closed pipelines. Water is applied directly, or very near to the soil surface, either above or below the ground surface, in discrete drops, continuous drops, small streams, or spray. Flows and pressures are typically low. A wide variety of emitters are available to dissipate pressures at points, allowing water applications to the soil in small amounts with little force. The trickle irrigation category includes methods such as drip, subsurface, bubbler, and spray irrigation.
