The groups are:
• Flood irrigation systems by which
water that flows under gravitation
is applied to the farm lands. This
includes basin, border, furrow and
short furrow.
• Mobile irrigation systems which
move over the farm land under its
own power while it irrigates. This
include centre pivot, linear and
travelling gun.
• Static systems include all systems
that remain stationary while water
is applied. We distinguish between
two types:
- Sprinkler by which water is
supplied above ground by means of
sprinklers or sprayers. This
includes permanent or portable
like quick-coupling, drag-line, hopalong, big gun, sideroll and
boom irrigation systems.
- Micro which includes microsprayers, mini-sprinklers and drip
irrigation systems.
Water
The amount of available water, the
quality of the water and the cost
thereof may influence the choice of
an irrigation system. If the amount
of available water is a limiting
factor on the area to be irrigated, it
might be more profitable to select a
micro irrigation system, with a high
water
use
efficiency.
Where
irrigation contains harmful chemical
substances that could burn the
leaves of the plant or influence the
quality of the product, overhead
irrigation systems that wet the
foliage should be avoided.
Soil
For micro irrigation of soils with a
very high sand fraction, micro
sprayers would be preferable to
drippers. However, if the soil has a
very high clay fraction and a low
infiltration rate, a dragline system
might be more suitable than a
centre pivot is and an overhead
system is to be installed.
Topography
Topography plays an important
where systems such as linear
flood
irrigation
systems
concerned and may dictate
choice of a system.
role
and
are
the
Climate
In very hot climatic conditions,
water applied by sprinkler irrigation
that wets the leaves of plants may
burn the leaves. Under such
conditions it would be better to use
a micro system or a flood irrigation
system.
Energy Costs
Energy requirements and therefore
operating costs of some systems
such as the big gun, travelling gun
and the high-pressure travelling
boom are considerably higher than
for low-pressure systems such as,
for e.g., drip irrigation, and should
therefore be take into consideration
with system selection.
Crop
The crop to be irrigated will highly
influence the choice of an irrigation
system. It would be ineffective to
irrigate wheat with a drip system
which is only suitable for row crops.
It would also be difficult to move
portable pipes of a quick coupling
system in an orchid.
Labour
A shortage of labour may force the
farmer to use self propelled or
permanent systems rather than
movable systems.
Capital Cost
Micro
irrigation
systems
are
generally more expensive than for
instance portable systems. The
farmer may for economic reasons
rather select the cheaper portable
system, even though it might not
be the ideal system for the
application.
Personal Considerations
Although each system has its own
field of application, the final choice
rests with the user of the system,
the farmer. Each farmer has his
own personal preferences that are
influenced by various factors, for
instance whether the system is
adaptable to his current farming
practice, the level of training of his
labourers, whether or not the
system can be adapted for other
uses and the reliability of the
supplier.
CONCLUSION
The success or failure of an
irrigation system depends to a large
extent
on
careful
selection,
thorough planning, accurate design
and effective management.