Irrigated farmingDrip irrigationSprinkler irrigationWater distribution

Mengiste, A.

English

Research Papers in Economics

MoWR/MoARD/USAID/IWMI Workshop  75 
Private –public Partnership and Technological 
Imperatives for Irrigation Development 
Alemayehu Mengiste  
Agritec System P.L.C, Addis Ababa, Ethiopia 
agrsys@ethionet.et 
 
Abstract 
In irrigated agriculture, water taken up by crops 
is partly or totally provided through human 
intervention.  Irrigation water is withdrawn 
from a water source (river, lake or aquifer) and 
led to the field through an appropriate 
conveyance infrastructure. 
 
There is a marked difference in yield response 
and water requirements between irrigated and 
non-irrigated agriculture.  Irrigated crops 
produce better yield than rain fed crops because 
of their higher water consumption even if those 
rain fed crops get optimal inputs.   
 
Experience shows that rain fed agriculture have 
been unable to meet the food requirement of the 
Ethiopian population. The present annual per 
capita consumption of cereals and pulses in the 
country is 163kg compared to UNICEF 
standard of 240kg and that of the average for 
developing countries of 230kg (2100 Calories). 
Even though considerable increase in 
production can be attained through 
intensification of the rain fed agriculture, it is 
bound to fall short of the ever increasing 
population.  
 
The terms “drip”, “trickle” and “sprinkler” 
irrigation, common in many parts of the world 
in the last 15 years have been emphasized by 
the term “micro irrigation”, “low volume 
irrigation”. Micro irrigation includes all 
methods of frequent water application, in small 
flow rates, on or below the soil surface. 
 
This is probably the promising technology 
choice in terms of water management, fertilizer 
application, crop protection & increased yield. 
Considering the need to cop up with growing 
demands, the choice of appropriate technology 
is eminent. The technology choice is mainly 
dictated by the cropping pattern, the level of 
sophistication & the operational capacity of end 
users, the optimum combination of efficiency in 
water use and cost effective operation and 
maintenance. 
 
The terms “drip”, “trickle” and “sprinkler” 
irrigation, common in many quarters in the last 
15 years have been supplanted by the term 
“micro irrigation”, recently adopted by the 
American Society of Agricultural Engineers. 
Micro irrigation includes all methods of 
frequent water application, in small flow rates, 
on or below the soil surfaces. 
 
  Regarding irrigation development areas of 
cooperation between the private and public 
sector could be mainly in a)technology choice 
and adaptation b)financing and resource 
mobilization c)rural entrepreneurship and 
private sector development. 
 
Micro irrigation systems have many potential 
advantages when compared with other 
irrigation methods. These are mainly: use of 
smaller flow rate, controlled application of 
chemicals, use of saline water, improved 
quality of crop, adaptation to any topography. 
1. Irrigation and Current Crop 
Production System of Ethiopia 
1.1. General 
In irrigated agriculture, water taken up by crops 
is partly or totally provided through human 
intervention.  Irrigation water is withdrawn 
from a water source (river, lake or aquifer) and 
led to the field through an appropriate 
conveyance infrastructure.  To satisfy their 
water requirements, irrigated crops benefit both 
from more or less unreliable natural rainfall and 
from irrigation water.  Irrigation provides a 
powerful management tool against the vagaries 
of rainfall, and makes it economically attractive 
to grow high-yielding seed varieties and to 
apply adequate plant nutrition as well as pest Private-public partnership and technological imperatives for irrigation development  
76   MoWR/MoARD/USAID/IWMI  Workshop 
control and other inputs, thus giving room for a 
boost in yields (FAO, 1996).  Irrigation is 
crucial to the country’s food supplies.  
1.2. Yield Response 
There is a marked difference in yield response 
and water requirements between irrigated and 
non-irrigated agriculture.  Irrigated crops 
produce better yield than rain fed crops because 
of their higher water consumption even if those 
rain fed crops get optimal inputs. The water 
consumption for rain fed agriculture stops at 
5,500 m
3/ha as it is impossible for ‘typical’ rain 
fed crops to consume more water. The 
corresponding yield is estimated to be 
5000kg/ha. Whereas the irrigation crops water 
consumption could go up to 6500m
3 /ha with a 
corresponding yield of over 7500kg/ha. 
1.3. Food Balance 
Experience shows that rain fed agriculture have 
been unable to meet the food requirement of the 
Ethiopian population (See table 1). The present 
annual per capita consumption of cereals and 
pulses in the country is 163kg compared to 
UNICEF standard of 240kg and that of the 
average for developing countries of 230kg 
(2100 Calories). Even though considerable 
increase in production can be attained through 
intensification of the rain fed agriculture, it is 
bound to fall short of the ever increasing 
population. Table 1 with a five years interval 
shows the required growth of irrigated 
agriculture in Ethiopia. It can be seen from the 
table that although the production from rain fed 
agriculture is expected to grow still additional 
production is required to meet the demands, 
which has to come from the irrigation sub-
sector. In order to achieve this nearly 1.5 
million hectares and nearly all of the 3.5 million 
hectares must be developed by 2020 and 2040 
respectively. 
2. Private-Public Partnership for 
Irrigation Development 
2.1. General 
In present day agricultural production system, 
irrigation is effectively used to compensate for 
permanent water deficit & to smoothen climate 
variations mainly caused 
 
   
 
Table 1. Required food crop production & irrigation land 
Year 1995  2000  2005  2010  2015  2020 
Population (‘000)  53,277  60,965    70,297   82,689  96,806  113,234 
Annual Per Capita             
Food Consumption(KG)  150  160  170  180  190  200 
Total Requirement             
of Cereals (MT)  7.99  9.7544  11.95  14.88  18.39  22.64 
Production from rain fed             
Cultivation(MT) 7.491  7.99  8.49  8.99  9.99  10.99 
Balance Production from           
irrig. Agriculture(MT)  0.50  1.7644  3.46  5.89  8.40  11.65 
Production  rate for             
irrig. Agriculture(t/Ha)  6.5  7  7.25  7.5  7.75  8 
Required area under             
irrig Agriculture (Mha)  0.07  0.25  0.47  0.78  1.08  1.45 
Source: - The 1984 population & Housing Census of Ethiopia; Analytical Report at National level, Addis 
Ababa, Dec.1991 
    Alemayehu  Mengiste 
MoWR/MoARD/USAID/IWMI Workshop  77 
due to precipitation. Irrigated agriculture in 
Ethiopia from the point of view of technology 
can be categorized into traditional, modern-
community owned, modern- private, and 
modern-public. The traditional farms are mainly 
characterized by enormous water loss, 
uncontrolled water application, backward crop 
husbandry, etc. However, the modern ones are 
better in relative terms but still having less than 
45 % irrigation efficiency, particularly those 
that are under surface irrigation. Today there 
are very few but not exceeding an aggregate of 
some 3000ha under low volume (drip & 
sprinkler) modern irrigation systems. This is 
probably the promising technology choice in 
terms of water management, fertilizer 
application, crop protection & increased yield. 
Considering the need to cop up with growing 
demands, the choice of appropriate technology 
is eminent. The technology choice is mainly 
dictated by the cropping pattern, the level of 
sophistication & the operational capacity of end 
users, the optimum combination of efficiency in 
water use and cost effective operation and 
maintenance. 
2.2. Technological Choice and Research 
Apart from the formal higher learning 
institutions of the country, to date there is no 
center for irrigation technology choice & 
adaptation. This has immensely contributed to 
the stagnation of the backward irrigation 
technology we are utilizing. Therefore the 
establishment of a center for technology choice 
& adaptation is fundamental to the growth of 
irrigation development in the county. 
Adaptation of best practices from elsewhere in 
the country or from abroad could not be 
conducted using original scientific research, 
which is time taking & expensive but by 
employing adoptive research. 
 
The utilization of new technologies & farming 
practices of irrigation development would 
greatly benefit from adoptive research. It can 
also stimulate sustained growth & spread of & 
improved technologies. As water is becoming 
more critical for agricultural production, it has 
also more competing use & therefore efficiency 
of water use will be of prime concern as 
irrigation development widens.  
2.3. Financing Irrigation Schemes and 
Resource Mobilization 
The issue of financing is critical particularly 
when irrigation development is considered, 
since irrigation is finance intensive based on the 
technology chosen & the scale of intervention. 
The shining success in terms of food self 
sufficiency of India & China, the two mostly 
populated nations of our world, stems mainly 
from their use of appropriate planning & 
implementation together with suitable 
technology of irrigation including massive 
mobilization of their people and indigenous 
resources (both finance & human resource).  
2.4. Rural Entrepreneurship and Private 
Sector   
The rural economy needs to be diversified from 
the mono tuned crop-livestock production 
system into other economic activities that are 
either agricultural based or in trade, service & 
rural industry. The introduction of irrigation 
yields the opportunity for diversified business 
activities. As income increases due to surplus 
production of irrigation, there will be increased 
demand for non - farm products & services. 
Hence, the private sector will be involved to 
handle these business activities.  As these 
activities require financial & institutional 
support, the role of the government will be to 
enhance the rural business areas, facilitate or 
avail capital in a form of credit or incentive & 
guide in running the businesses and in general 
develop rural entrepreneurship & private sector 
participation. 
3. Technological Imperatives for 
Irrigation Development  
3.1. General  
The terms “drip”, “trickle” and “sprinkler” 
irrigation, common in many quarters in the last 
15 years have been supplanted by the term “low 
volume irrigation” or “micro irrigation” as 
recently adopted by the American Society of   
Agricultural Engineers. Low volume irrigation 
includes all methods of frequent water 
application, in small flow rates, on or below the 
soil surface. Ideally, the volume of water is Private-public partnership and technological imperatives for irrigation development  
78   MoWR/MoARD/USAID/IWMI  Workshop 
applied directly to the root zone in quantities 
that approach the consumptive use of the plants.  
3.2. Components of a micro Irrigation 
System  
In micro or low volume irrigation systems, 
water is distributed using an extensive hydraulic 
pipe network that conveys water from its source 
to the plant. Outflow from the irrigation system 
occurs through emitters placed along the water 
delivery (lateral) pipes in the form of droplets, 
tiny streams or miniature sprays. The emitters 
can be placed either on or below the soil 
surface.  
 
Emitters can vary from sophisticated, constant-
flow-rate at variable pressure types of devices 
(pressure compensating emitters) to very small, 
simple orifices. A large number of different 
types of emitters have been developed in 
attempts to find a perfect one. The main 
objective is to assure uniformity of water 
distribution. It is essential that the discharge 
from the emitter be uniform and that it not 
change significantly with small pressure 
variations in the system. At the same time the 
emitter should be constructed in such a way that 
it does not clog very easily (figure 1). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1. Plastro emitters (PC and PCND 
types) 
3.3. Wetting Patterns under Micro 
Irrigation  
Due to the manner in which water is applied in 
a micro irrigation system, only a portion of the 
soil surface and root zone of the total field is 
wetted. Water flowing from the emitter is 
distributed in the soil by gravity and capillary 
forces creating the contour lines. The exact 
shape of the wetted volume and moisture 
distribution will depend on the soil texture, 
initial soil moisture, and to some degree, on the 
rate of water application (figure 2) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 2. Typical wetting pattern of drip 
irrigation system 
4. Consideration for Selecting the 
Most Appropriate Irrigation 
Application 
4.1. General  
Micro irrigation systems have many potential 
advantages when compared with other 
irrigation methods. Most of them are related to 
the low rates of water application.  
 
Irrigation water requirements can be smaller 
with micro irrigation when compared with other 
irrigation methods. This is due to irrigation of a 
smaller portion of the soil volume, decreased 
evaporation from the soil surface, and the 
reduction or elimination of the runoff. 
4.2. Smaller Flow Rates 
Since the rate of water application in micro 
irrigation systems is significantly lower than in 
other systems, smaller sources of water can be 
used for irrigation of the same acreage. The    Alemayehu  Mengiste 
MoWR/MoARD/USAID/IWMI Workshop  79 
delivery pipes, the pump, and other components 
of the system can be smaller and therefore more 
economical.   
4.3. Application of Chemicals 
Micro irrigation system allow for a high level of 
control of chemical applications. The plants can 
be supplied with the exact amount of fertilizer 
required at a given time. Since they are applied 
directly to the root zone a reduction in the total 
amount of fertilizer used is possible.  
 
Other chemicals, such as herbicides, 
insecticides, fungicides, nematicides, growth 
regulators and carbon dioxide can be efficiently 
applied through micro irrigation systems to 
improve crop production. 
4.4. Water Sources with High Salt 
Content 
A significant advantage of micro irrigation is 
that water with relatively high salt content can 
be used by the system. For optimum plant 
growth a certain range of total water potential in 
the root zone must be maintained. The potential 
defines how difficult it is for a plant to extract 
water from the soil. Large negative numbers are 
characteristic of very dry soils with low total 
water potentials while potentials near zero 
reflect soils near saturation.  
4.5. Improved Quality of the Crop 
Micro irrigated plants are supplied very 
frequently with small amounts of water and the 
stress due to the moisture fluctuation in the root 
zone is reduced to the minimum, often resulting 
in larger and better quality yield. In arid 
climates, or during dry seasons, the harvest ting 
can be controlled by proper water management.  
4.6. Adaptation to Any Topography 
Micro irrigation systems can operate efficiently 
on hilly terrain if appropriately designed and 
managed. Well managed micro irrigation 
system will not create runoff even on hilly 
terrain. 
4.7. Additional Advantages of Micro – 
Irrigation Systems  
During dry seasons or in arid climates disease 
and insect damage can be reduced in micro 
irrigation system since the foliage of the plant is 
not wetted. With a small portion of soil surface 
being watered, field operations can be 
continued during irrigation. The water 
distribution is not affected by the wind for drip 
irrigation. However, wind can have some effect 
on jet spray patterns. 
References 
Alemayehu Mengiste, 2005. Symposium on 
modern irrigation technologies. Organized 
by Agritech Systems, Concert Engineering 
and Plastro Irrigation, Ghion Hotel, Addis 
Ababa. 
Nir Aloni, 2005. Symposium on modern 
irrigation technologies. Organized by 
Agritech Systems, Concert Engineering and 
Plastro Irrigation, Ghion Hotel, Addis 
Ababa. 
Ethiopian Economic Association, 2003. Report 
on the Ethiopian Economy. Volume III. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Ethiopian Economic Association,

Symposium on modern irrigation technologies. Organized by Agritech Systems, Concert Engineering and Plastro Irrigation, Ghion Hotel, Addis Ababa.

Private-public partnership and technological imperatives for irrigation development

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Private-public partnership and technological imperatives for irrigation development

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