Climate Change Adaptation - Climate Resilient Agriculture for Ensuring Food Security - page 241

Table 12.4 Response of different crops to sprinkler
irrigation systems (INCID 1998 )
Crops

and may also be costly. Mechanized sprinkler
irrigation systems have a relatively high energy
demand (Savva and Frenken 2002 ).

Water saving %

Yield increase %

Barley 56 16

Cabbage 40 3

Caulifl ower 35 12

12.3.4 Drip Irrigation

Chilies 33 24

Cotton 36 50

Drip irrigation is based on the constant applica-
tion of a specifi c and focused quantity of water to
soil in the region of feeder roots of crops. The
system uses pipes, valves, and small drippers or
emitters transporting water from the sources (i.e.,
wells, tanks, and or reservoirs) to the root area
and applying it under particular quantity and
pressure specifi cations. The system should
maintain adequate levels of soil moisture in the
rooting areas, fostering the best use of available
nutrients and a suitable environment for healthy
plant roots systems. Managing the exact (or
almost) moisture requirement for each plant, the
system signifi cantly reduces water wastage and
promotes effi cient use. Compared to surface irri-
gation, which can provide 60 % water-use effi -
ciency and sprinkler systems which can provide
75 % effi ciency, drip irrigation can provide as
much as 90 % water-use effi ciency (FAO 2002 ).
In recent times, drip irrigation technology has
received particular attention from farmers, as
water needs for agricultural uses have increased
and available resources have diminished. In par-
ticular, drip irrigation has been applied in arid
and semiarid zones as well as in areas with irreg-
ular fl ows of water (or in zones with underground
water resources that rely on seasonal patterns
such as river fl ow or rainfall).
Drip irrigation zones can be identifi ed based
on factors such as topography, fi eld length, soil
texture, optimal tape run length, and fi lter capac-
ity. Many irrigation system suppliers use com-
puter programs to analyze these factors and
design drip systems. Once the zones are assigned
and the drip system is designed, it is possible to
schedule irrigations to meet the unique needs of
the crop in each zone. Recent automatic systems
technology has been particularly useful to help
control fl ows and pressure and to identify poten-
tial leaks, thereby reducing labor requirements.
System design must take into account the effect

Groundnut 20 40

Maize 41 36

Onion 33 23

Potato 46 4

Wheat 35 24

types of soil, except heavy clay. Sprinkler sys-
tems can be installed as either permanent or
mobile fi xtures. Sprinklers provide a more even
application of water to agricultural land, promot-
ing steady crop growth. Likewise, soluble fertil-
izers can be channeled through the system for
easy and even application. The risk of soil ero-
sion can be reduced because the sprinkler system
limits soil disturbance, which can occur when
using irrigation by gravity. In addition, sprinkler
irrigation can provide additional protection for
plants against freezing at low temperatures.
Secondary benefi ts from improved crop produc-
tivity include income generation, employment
opportunities, and food security.

12.3.3.2 Disadvantages
The main disadvantages associated with sprin-
kler systems are related to climatic conditions,
water resources, and cost. Even moderate winds
can seriously reduce the effectiveness of sprin-
kler systems by altering the distribution pattern
of the water droplets. Likewise, when operating
under high temperatures, water can evaporate at a
fast rate, reducing the effectiveness of the irriga-
tion. Although sprinkler irrigation can help farm-
ers to use water resources more effi ciently, this
technology relies on a clean source of water and
therefore may not be suited to areas where rain-
fall is becoming less predictable. Implementation
costs are higher than that of gravity-fed irrigation
systems, and large labor force is needed to move
pipes and sprinklers in a nonpermanent system.
In some places, such labor may not be available