The term `modern technology' in relation to irrigation usually refers to on-farm irrigation systems such as sprinkler and trickle irrigation. It can also mean the introduction of piped distributions systems for surface irrigation as well as the use of treadle pumps (a recent innovation in Africa) or the use of petrol and diesel driven pumps in areas where such technology is not normally used. Some professionals and policy-makers perceive modern technologies as an intervention that can improve crop yields and quality and, at the same time, reduce water wastage (a better term to use than irrigation efficiency which can be misleading).
Most modern technology developments have been driven by the needs of the developed world to reduce labour inputs, keep energy costs as low as possible and reduce water wastage while maintaining operational reliability. In the irrigation sector it is the large commercial agricultural enterprises that have driven such developments and the results have been impressive. Production costs have fallen and crop yields and quality have improved.
Can similar benefits be realised by smallholders in developing countries? Cornish (1998) summarises the issues. He quotes Hillel (1989) who expressed concerns about the way in which manufacturers, and farmers as customers for their products, in the developed world are fascinated by sophisticated technology and eager to have more specialised and intricate hardware to use. He states that `In the non-industrial countries, the important attributes are, low-cost, simplicity of design and operation, reliability, longevity, few manufactured parts that must be imported, easy maintenance and low energy requirements.' Hillel also suggests that generally the `labour economy is less important.' Plusquellec et al. (1988) also argued that one of the driving forces for sprinkle and trickle irrigation development has been the interest and investment on the part of private sector manufacturers of irrigation equipment. For the majority of smallholders in developing countries growing staple crops with existing surface irrigation schemes and low labour costs, returns can seldom justify the capital expenditure associated with equipment.
Keller (1990) says that modern technology can result in less water wastage because water is conveyed in pipes and irrigators can control the amount of water applied and its timing more easily which can increase productivity per unit of water. He suggests that traditional methods have limited productivity and are dependent on a farmer's willingness to invest in land preparation and coaxing water to spread evenly over the land. Buying modern irrigation equipment is trading money for labour and skill. Keller also stresses that the opportunity cost of money for smallholders is very high whilst that of labour and traditional skills is low. Farmers will make the investment in modern equipment only when the financial return is clear and relatively assured. For many poor farmers, the idea of a cash investment is inconceivable without credit and institutional support that ensures success. Very few farmers in Europe and the USA survive without subsidies and financial support from governments yet poor farmers in Africa are expected to stand on their own feet with little or no support.
Modern technologies are unlikely to be taken up by poor subsistence farmers because they are mostly concerned with food security and minimizing risk. These technologies are more likely to be adopted by farmers that have been able to diversify farming income beyond basic food crops and who are able to consider marketing produce outside the home. The issue here is how to help farmers move into the income-generating category through the development of a range of coping strategies.
How successful have these technologies been in the developing world as opposed to the more sophisticated social and economic environments of the developed world? Are the traditional technologies being ignored because it is psychologically easier to invest in sprinkler and trickle irrigation, which are perceived as `efficient and modern', whereas surface irrigation is regarded as `old and inefficient'? Most important, are the new technologies, which are supposed to improve irrigation and reduce risk, only introducing new problems that might expose farmers to a higher level of risk than before?
Some useful sources of information include Cornish (1998) who provided a thorough review of modern technologies for smallholders in developing countries. He points out that many modern technologies are not suited to smallholder irrigation. Cornish lists available technologies and identifies features making them suitable for use by smallholders. Kay (1983) provides practical details of a wide range of sprinkle irrigation equipment and Keller and Bleisner (1990) describe both sprinkle and trickle irrigation systems in detail as well as providing design examples. Kay and Brabben (2000) have recently published a review of the potential for the use of treadle pumps in Africa. Bentum and Smout (1994) produced a report, which reviews the use of buried pipelines for surface irrigation and their potential to improve water management and reduce water wastage.
Sprinkle irrigation is used on approximately 5 percent of irrigated land throughout the world, the majority of which is in developed countries. It is unlikely to replace the large areas under surface irrigation, (essentially the remaining 95 percent, except for a small amount of trickle). Sprinkle irrigation has a distinct advantage, because good water management practices are built into the technology. Sprinkle irrigation technology can provide the flexibility and simplicity required for successful operation, independent of the variable soil and topographic conditions. Pumps, pipes and on-farm equipment can all be carefully selected to produce uniform irrigation at a controlled water application rate and, provided simple operating procedures are followed, the irrigation management skills required of the operator are minimal. This puts the responsibility for successful irrigation in the hands of the designer rather than leaving it entirely to the farmer. Sprinkle can be much simpler to operate and requires fewer water management skills. However, it requires sophisticated design skills and on-farm support in terms of maintenance and the supply of spare parts.
Sprinkle is potentially less wasteful of water and uses less labour than surface irrigation. It can be adapted more easily to sandy soils subject to erosion on undulating ground, which may be costly to re-grade for surface methods. There are many types of sprinkle systems available to suit a wide variety of operating conditions. The most common for smallholders is a system using portable pipes (aluminium or plastic) supplying small rotary impact sprinklers. Because of the portability of sprinkle systems they are ideal for supplementary as well as total irrigation.
At the forefront of sprinkle developments is the centre pivot machine, which can irrigate up to l00 ha at a time. These machines are very adaptable. In the United Kingdom they have been used on small and irregular shaped fields crossing field boundaries to irrigate several fields growing different crops at the same time. One machine was used to irrigate several farms where the farmers decided to cooperate. Here the farmers' role in irrigating large areas having multiple ownership and minimal inputs should not be underestimated. Libya is a well-known example of their use for irrigating large desert areas. As far as the farmers under the pivots were concerned it rained once a week as the pivot rotated. From a management point of view sprinkle irrigation provided a relatively simple system to operate and allowed farmers to do the farming. Although the skills needed to operate these machines and to maintain them must not be underestimated, they are no more than those required to keep motorcars running. In most developing countries technicians do this very successfully in the private sectors. This is not so much to advocate the widespread use of centre pivot machines for smallholders but to point out that technology can be very adaptable and can be used in innovative ways when the conditions are right.
Table 2 provides a summary of the different sprinkle systems available.
Uses small rotary impact sprinklers
Similar to portable. Lower labour input
Mobile gun systems
Large gun sprinklers that can be replaced by boom. Good for supplementary irrigation
Mobile lateral systems
Large automatic systems. Ideal for large farms with low labour availability
Fixed spray nozzles. Suitable for small gardens and orchards
Sprinkle irrigation was mainly developed for larger farms. The system is not very flexible and adaptable to the multitude of small plots usually found on small farms. In some cases there are ways around the problem, such as using the same equipment in imaginative ways as can be seen in the following section, which is based on experience gained in Zimbabwe. New ideas are being developed for equipment specifically suited for use by the small farmer both in terms of technology and cost.
Cornish (1998) lists several countries where sprinkle irrigation has been used to support smallholder development in countries outside of sub-Saharan Africa such as Jordan, Israel, Cyprus and others. The problem is that most reports do not usually answer such important questions as to who pays for the equipment, who owns and runs the schemes and just how successful they have been in meeting users aspirations.
Zimbabwe is special when it comes to irrigation equipment because it has a history of large commercial farming (200 ha and more) on which a sprinkle and trickle irrigation manufacturing, distributing and support network has grown. Zimbabwe also has a large smallholder farming community and attempts have been made to adapt these same systems to their needs. Satisfying one large farm having a single crop is rather different from satisfying 200 farmers on the same land area growing many different crops at different times. The technical problems of adaptation can be considerable. Diemer (2000) looked at a sprinkle scheme where the layout normally used for large commercial farms was transferred without change to the smallholder situation. It created endless management problems that were eventually solved by re-arranging the same equipment in a different layout. By using flexible hoses to supply water to sprinklers rather than the rigid aluminium pipe layout this system was found to be much more adaptable to the needs of smallholders.
The government irrigation design and construction service, Agritex, has been at the forefront of developing new schemes for smallholders. A recent, comprehensive study (FAO 2000) of ten smallholder schemes (six sprinkler and four surface) has highlighted some of the successes and failures. The schemes are all typical smallholder developments that were initiated and financed by a government agency to stimulate development. All have several farmers sharing the same water source and distribution system. All have been handed over to the farmers for them to operate and maintain. Two examples, a success and a failure, are highlighted in the box.
Chitora, Zimbabwe - a success
This is a small scheme irrigating only 9 ha with drag-hose sprinklers. It is one of the most successful farmer managed irrigation schemes in the country. In operation since 1994, it is run by young people aged 22 to 27 years who were without jobs and were dependent on their parents for everything. The parents felt they were too old to engage in irrigated agriculture and so 18 of their children accepted the offer of irrigation support from the Agritex the government irrigation development agency. Agritex provided all the inputs for the scheme including those for the first growing season. From then on the young farmers had to finance the scheme themselves. They were involved at every stage of development from planning to implementation and now have full responsibility for operation and maintenance.
The cropping programme is essentially for high value horticultural crops grown for the markets on the outskirts of Harare where there is a demand for good quality vegetables. Grain maize is not grown because farmers argue that it is cheaper to buy it elsewhere than to produce it themselves. The argument is based on the principle of opportunity cost.
Farmers income averages Z$60 000 per year compared with that of Z$16 800 for unskilled labour wages in the town. The farmers see no reason to migrate into the towns where they are well aware that their costs of living would be much higher.
The scheme is entirely farmer managed through a system of bye-laws enforced by an Irrigation Management Committee that is responsible for coordinating all scheme activities including payment of bills for electricity, maintenance work, monthly subscriptions from farmers, maintaining discipline in the scheme and reallocating plots.
The farmers continue to receive support from Agritex in the form of training and extension services. The successful performance of the scheme is reportedly a result of the farmers' sense of ownership and their belief that the scheme belongs to them. It is not possible to say what role technology played in this success. Undoubtedly water management was made easier to deal with and the availability of spare parts and technical support in Zimbabwe must add to the security of farmers using such systems.
Ngezi Mamina, Zimbabwe - a failure
This is a communal scheme built at the same time as Chitora but on a larger scale as part of an aid project associated with dam construction. It is typical of a government built and run irrigation scheme that has run into difficulties in getting farmers to `own' the scheme originally constructed for their benefit. The scheme covers 216 ha with 154 plots ranging from 0.5 to 1.5 ha. Irrigation is by sprinklers fed by gravity therefore avoiding the problems of pumping. Low value crops are grown with very few high value vegetables. Since its inception in 1994 the scheme has not run well. Farmers claimed they were never consulted about the scheme and were afraid they would lose their land. It continues to be run by the Government, which also pays for electricity, water and services. This leads to scant regard for the use of water and electricity by the farmers. Farmers are reluctant to take over the responsibility of running and maintaining the scheme themselves and complain that the infield designs are inadequate, which leads to regular disputes between the farmers and government institutions.
Except in one or two cases where there was reference to poor design of layouts and equipment, the technology used was not a major determinant in the success or failure of the schemes, although it may have played a role. Sprinklers can simplify irrigation management and although it was not discussed, the long history of sprinkle irrigation in the country is likely to have created confidence among farmers that the technology would work well and if not then it would not be difficult to get it fixed.
What is clear from the study are the complex social, economic, technical and institutional issues surrounding smallholder irrigation schemes making each one unique and demonstrating the importance of getting the mixture right. It also emphasises the point made by others that small-scale does not mean simple.
The FAO study has some general conclusions:
One interesting fact, which is not raised by other investigators, is the age profile of the farmers on the Chitora irrigation scheme. It is well recognized throughout the world that younger people tend to be more receptive to new ideas, particularly to new technology, and may also be in a position to take greater risks than their elders who have more family responsibilities. Targeting young farmers may be one strategy that is worthy of further attention.
Experience from outside the region
Mexico has a history of irrigated agriculture having over 6 million ha under irrigation. (Manuel and Maldonado 1999). Sprinkle irrigation has long been used to support smallholder irrigation development on a large scale and in particular by FIRCO (Trust Fund for Shared Risk) which is part of the Secretariat of Agriculture, Livestock, and Rural Development of the Government of Mexico.
A recent development was undertaken in a hilly region of the country. During the three years of this programme it was reported that 1 000 sprinkler irrigation modules (each of 0.1 ha) were installed in 60 communities belonging to 35 different municipalities. The reason given for using sprinklers and trickle was water scarcity and the problems related to using more traditional methods of irrigation. The cost of materials was US$500/ha. Installation costs were borne by the farmers who contributed their labour and government engineers provided technical assistance. The main crops grown included corn and beans mainly for self-consumption as both staple crops are expensive for isolated communities who are distant from markets. Farmers were reported to be seeking to change their cropping pattern to satisfy both their home needs and to grow vegetables for the city markets.
Although there were no indications of the extent of farmer funding and involvement in the scheme, Mexico has a well-developed irrigation sector and it is likely that this scheme will build on this tradition. Whether it is ultimately successful remains to be seen.
An interesting development has been underway since 1981 using large mobile irrigation machines as part of the Taung project in South Africa. Centre pivots and linear move machines were installed with the aim of providing income and livelihoods for smallholders on farms varying in size up to 10 ha, cropping wheat, barley, corn, peanuts and cotton (Valmont personal communication). The project, which was originally installed to settle farmers in the former `homelands', so far has 73 pivots installed each irrigating 40 ha. The operation and maintenance services are all contracted out to an independent contractor whose role is to keep the irrigation system running. Government supports the farmers through a full range of extension services. The installation costs were estimated to be around US$1 000/ha. Unfortunately there is very little information available about how successful and sustainable this kind of development can be. There are worrying signs that the approach may be too `top-down.'
Trickle or drip irrigation comprises a system of pipes and emitters that can deliver small frequent irrigations to individual plants. This technology can provide farmers with a method of precise control over the timing and amount of irrigation and so they can easily meet the crop water demand without wasting water. Wastage can only occur if the system is left running for too long or there are leaks in the pipes.
Trickle irrigation is not yet widely used on a world scale, and covers less than 0.1 percent of irrigated land. Even in Israel, where much of the early research and development was done and water is very scarce, trickle has not flourished as much as might be thought. Sprinkle irrigation still provides more than 70 percent of Israel's irrigation because this is still considered to be a most efficient method of irrigation and one that is financially viable.
Claims made about crop yields and water saving need to be judged with care. Sales people often imply there is something magic about trickle irrigation when they refer to substantial increases in yield and savings in water use. There is no magic. Crops respond primarily to water and not so much to the method of application. They need the same amount of water to grow properly whether this is applied with trickle irrigation or with surface flooding methods. If the right amount of water is applied to the crop at the right time it will flourish. Similarly, water savings can only be made by reducing wastage and not by reducing the amount of water the crop needs. Ironically many farmers end up applying more water when using trickle irrigation because the system allows them to apply water more easily than with other methods.
A major technical problem with trickle irrigation is emitter and lateral blockage from sand and silt, chemical precipitation from groundwater and algae from surface water. Each of the problems takes the use of trickle into a level of technology and support that can be difficult to sustain in a developing country. However, on a small scale the farmer can simply go around and clean the system regularly, which can overcome these problems. On a larger scale this would not be practicable.
However, there are conditions that make this method of irrigation a very attractive option. It is ideally suited to areas where water is scarce or expensive, where water may be saline, where labour costs are high and where soils are poor. An important advantage is the ease with which nutrients can be applied with the irrigation water. This is much more difficult to do with other irrigation methods.
A distinct advantage of trickle for smallholders is the way in which it can be adapted to small and varied plots of land. This is how trickle is being used in India where farmers have gone from surface irrigation to trickle and have by passed sprinkle because it is considered an inflexible system for use on small plots. Local manufacture of trickle parts has encouraged Indian farmers to take up the method where they are assured of spare parts.
A further advantage of trickle is the ease with which it can be operated. It is a pipe system and so can be switched on and off easily. The potential for making timely and adequate irrigations as well as for reducing water wastage is good. The challenge is to realise that potential.
A critical issue for smallholders is the cost of trickle irrigation. It does tend to require a larger capital layout than most other methods of irrigation. The cost may well be justified by improved crop production and hence financial returns for farmers. The high initial cost as a result of the solid set nature of the system, its reliance on precision-engineered components and need for water filtration, all of which can be expensive.
Farmers solve their own problems in Ghana
A small-scale irrigation project was established on the outskirts of Khumasi for a group of women growing vegetables for the local markets. The scheme uses open irrigation channels supplying many plots, less than 0.1 ha each owned by a different person. The scheme was designed and built to supply water on a rotational basis and each woman was given an allotted time when she would receive water. The women objected to the scheme and said that the rotation was unworkable because they had lots of other household and family duties that took priority over irrigation. They solved the problem themselves by building small storage tanks on their farms. This allowed them to receive water when it was available and to irrigate their crops when it was convenient to them.
The cost of a trickle system is determined by crop type, row spacing and the total field area irrigated. System costs can range from US$1 000-3 000 per ha (Cornish 1998). In addition the systems require skilled management for effective operation and maintenance - filters require regular cleaning, systems may require periodic flushing to prevent build-up of slime. Equipment must be regularly inspected to identify and replace damaged components. The combination of high cost and demanding technical management means that conventional trickle technologies are normally considered to be inappropriate for resource poor, smallholder farmers.
Little has been reported on the use of trickle irrigation in sub-Saharan Africa. There is, however, a growing experience of its use in similar developing countries. In India, trickle irrigation has been introduced for high value crops (vegetables, flowers, spices) in some of the more arid parts of the country where water is scarce. In 1993 it was reported (Singh et al) that over 50 000 ha were being irrigated by trickle irrigation, this has now risen to over 225 000 ha. This substantial increase in the use of trickle methods is not so much a result of market demand but the low-cost of the systems, which are heavily subsidised by the Indian Government. Over the past ten years more than 100 companies have been set up to produce trickle equipment. Claims of water savings as high as 30-60 percent and yield increases of 20-40 percent have been made. Success was, however, masked by heavy subsidies. Even with subsidies the systems were too expensive for most small farmers. Trickle systems were also thought to be too complicated to operate and maintain and not easily divisible to fit small plots (Polak and Sivanappan 1998).
Most smallholders in sub-Saharan Africa use surface irrigation methods and distribute water using open channels. When several smallholders use the same water source and distribution system then there are greater risks of failure. The result all too often is poor water distribution and unreliable and inadequate water supplies to the field.
Most smallholder irrigation schemes use open channels to supply water because they are considered cheap and simple to use. In reality, from a management point of view, this type of irrigation is the most complex and inflexible of supply systems. Open channels can only be used for fixed schedules, flows are often unreliable and inadequate and distribution between the various canals is often difficult to manage. Even the choice of gates (weirs and sluices) for discharge and water level control can exacerbate the problems leading to the classic "top-end versus tail-end" problems of water distribution along canals.
Canal management can be simplified through use of relatively simple technologies, such as fixed regulators (e.g. solid weirs), or by building small storage reservoirs along the canals or replacing canals with pipes.
Constructing small storage reservoirs along canal system or on farms means farmers can take water as and when they need it and suppliers can supply as and when it is convenient to them. The reservoirs work in very much the same way as domestic water storage. The simplest example of this is water storage in dams, where water is held back in times of flood for use in the drier seasons. Storing water underground is much the same idea. The ground conveniently holds the water so that it is available for pumping when the farmer chooses to irrigate.
Storage in the supply system itself has been widely exploited in the Sudan and in schemes in northern Nigeria. This is usually storage over a short period of 24 hours. Although it adds to the cost of a scheme the benefits in terms of reduced water wastage can be significant.
Burying pipelines to replace canals offers an opportunity to simplify water management and reduce wastage (Bentum and Smout 1994). They use examples in Bangladesh for much of their conclusions on the benefits of pipe systems. Similar benefits were reported in India (Campbell 1984) and in Sri Lanka (Merriam 1987). Merriam has always argued that buried pipe distribution systems for surface irrigation represent an intermediate solution between lower cost earthen channels and the more expensive sprinkle and trickle systems.
Pipe systems are generally thought to be expensive. This term is relative in terms of the savings made in land and water. The simplification of management practices the additional cost may well be justified. However, there is little evidence of these systems being used in sub-Saharan Africa.
Modern technologies undoubtedly have the potential to raise the productivity of water and labour. Technically, they are best suited to conditions where water is scarce and the opportunity costs of labour are high. Modern technologies have yet to be seriously tested and evaluated in the region. There is also concern that their introduction into developing countries is driven more by commercial interests rather than need. This can lead to inappropriate use.
Experiences in Zimbabwe are of particular interest. Success in this country is clearly linked to the long history of sprinkle irrigation and support throughout the country by the private sector. The success of the small Chitora scheme, Zimbabwe, may be due in part to young people who are willing to accept new methods of working. This may be an important point to be borne in mind by developers when persuading farmers to change or take up modern systems.
What is clear is that modern systems are only accessible to farmers who can afford to buy them and who are growing cash crops such as vegetables, fruits and flowers providing sufficient returns to pay for the investment. Farmers will make the investment in modern equipment only when the financial return is clear and relatively assured. Modern systems have little to offer poor subsistence farmers and so are unlikely to be taken up by them.