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Irrigation and drainage
Evolution of irrigation development
Zambia’s irrigation potential is 2.75 million ha based on water availability and soil irrigability. From this potential, it is believed that 523 000 ha can be economically developed. However, the fact that different but not documented figures of the potential are quoted by other authors indicates the need for a systematic assessment to determine the correctness of the findings.
The following categories of irrigated farming are found in the country:
- Informal irrigation by small-scale farmers;
- Smallholder irrigation schemes;
- Former quasi-government schemes;
- Private or commercial irrigation schemes;
Since time immemorial, small-scale farmers all over the country have practised informal irrigation in their gardens, i.e. they applied water in an undocumented, casual, artificial way using buckets, watering cans and hosepipes to grow vegetables, rice, bananas and some local sugar cane varieties along streams, rivers and in dambos. This form of irrigation is usually not capital intensive, is farmer-operated and is often spontaneous in origin, responding to the needs felt by individual farmers. Drought occurrences, for example, directly prompt the genesis of such irrigation developments. Areas irrigated in this manner are usually small in size ranging from 100 - 200 m2. However, the introduction of treadle pumps has improved the efficiency of watering these gardens and farmers are now able to irrigate with one treadle pump areas ranging from 1 000 - 2 500 m2.
In the late 1960s to early 1970s, the Government developed and managed smallholder irrigation schemes through the then Projects Division of the then Ministry of Rural Development. These schemes included:
- the Buleya Malima (62 ha furrow irrigation), Nkadabwe (12 ha), Chiyabi (12 ha) and Siatwiinda (12 ha) schemes in the Gwembe valley;
- the Chapula (272 ha) horticultural scheme in the Copperbelt;
- the Luapula and Eastern provinces vegetable schemes;
- the Ikelenge pineapple scheme in Northwestern province;
- the Mulumbi and Lukulu North (6 000 ha) projects in Mansa and Kasama;
The primary objectives for the construction of such irrigation schemes were:
- Compensation for the land that local farmers lost, since they were displaced because of national projects such as the construction of the Lake Kariba dam in the Gwembe valley;
- Production of crops that would meet local community requirements, particularly for hunger relief during drought periods;
- Introduction and promotion of irrigated agriculture.
Most of these irrigation schemes have not performed well due to a top-down management approach, which did not empower farmers to operate and maintain them by themselves. Some of these irrigation schemes are in a collapsed state while others were not completed at construction stage. The Government’s current policy is to rehabilitate or complete construction of these schemes and then transfer the management responsibility for operation and maintenance of the systems to its beneficiaries.
Other irrigation schemes that followed the ones described above are parastatal schemes, which were initiated by the Government for the sole purpose of producing specific crops for throughput to their industries. Such crops included coffee (Kateshi and Ngoli irrigation schemes), bananas (Munushi and Chiawa schemes) and tea (Kawambwa scheme). These schemes range from medium- to large-scale irrigation schemes and include the Nakambala Sugar Estate developed by Tate and Lyle, which is now managed by the Illovo sugar group, a South African company.
The irrigation farms of the private and commercial sector cover some 37 015 ha in the large-scale irrigation schemes category. These have been developed purely on economic lines and grow high value commercial crops for export and local consumption. One single large scheme of its kind in this category is Nakambala Sugar Estate plc, which covers 11 349 ha. It has an out-grower scheme which includes the Kaleya smallholder scheme (2 383 ha), Garner (440 ha), Ceres (545 ha), Kapinga (81 ha), Syringa (80 ha), Mapula (235 ha), Anchor (33 ha) and Nanga Farms plc (1 272 ha). All these schemes grow sugar cane, which has satisfied local demand and some is exported. Other schemes producing sugar cane on a 2 000 ha land include the Nampundwe and the Northern Province sugar estates.
Until recently the majority of Zambians shunned irrigation with a view that it entailed huge investments requiring pump sets and pipe network. However, frequent and disastrous droughts, which led to the failure of rainfed crops, forced farmers to go into some form of irrigation using available surface water resources.
Currently 155 912 ha of land are irrigated in Zambia, which is about 30 percent of the economical irrigation potential (Table 4). It can be broken down as follows according to the technology used (Figure 3):
- 32 189 ha is under surface irrigation; sugar cane covers more than 50 percent of this area;
- 17 570 ha is irrigated by sprinklers; wheat accounts for 68 percent of this area;
- Drip irrigation covers some 5 628 ha; coffee production accounts for 92 percent of this area;
- Small-scale farmers are growing vegetables in dambos over an area of 100 000 ha, which are equipped with small drains, impoundment furrows and shallow wells for irrigating a wide range of vegetables in the dry season (May-October);
- Some of the small-scale farmers use treadle pumps to irrigate areas of about 525 ha; it is estimated that more than 3 000 treadle pumps are in use.
About 100 000 ha of non-equipped lowland areas are cultivated particularly in the rainy season in the interfluves. Around 10 ha around Lake Kariba is used for flood recession cropping (Table 4 and Figure 4).
Improved water management under rainfed agriculture has been advocated to realize the best possible water supply for the crops. This has been achieved through advocacy programmes for adopting conservation farming using micro-basins of sizes of 35 cm x 15 cm x 15 cm prepared by hand hoes. When it rains, they act as water harvesting basins that store water for much longer. This method has proved to yield 3 tonnes/ha of maize compared to 1.5 tonnes/ha using conventional methods. This performance has led to an accelerated adoption of this farming system. There are currently an estimated 200 000 ha under conservation and/or water harvesting farming by small-scale farmers. Although quite rare, supplementary irrigation is mainly practised by commercial farmers on fields that are planted with rainfed soybean in rotation with irrigated wheat. A few commercial farmers supplement cotton with irrigation before the onset of the rains in November.
Zambia’s irrigated areas equipped for full control irrigation can be broken down by size as follows (Figure 5):
- Small-scale and informal irrigation covers 11 000 ha (20 percent of total area) and is characterized by vegetables growing mainly on dambos and riverbanks. Shallow wells are dug and small drains where it is too wet to grow crops. Farmers use either treadle pumps or buckets tied to a rope for lifting water from these shallow wells or rivers.
- Medium-scale irrigation schemes cover 7 372 ha (13 percent) and commonly use motorized pumps (diesel or petrol).
- Large-scale commercial irrigation schemes cover 37 015 ha (67 percent) and use electrically driven pumps to lift water and irrigate large areas. Commercial crops like sugar cane, wheat and coffee are commonly irrigated in these schemes.
About 88 percent of the area equipped for full or partial control irrigation draws its water from surface water and 12 percent from groundwater (Figure 6).
Role of irrigation in agricultural production, the economy and society
Irrigated agriculture has been shown to yield two- to four-fold compared to rainfed agriculture. For example rainfed wheat yields between 1.5 and 2 tonnes/ha compared to the national figure of 6 tonnes/ha for irrigated wheat. Similarly rainfed maize yields 1.5 tonnes/ha using conventional methods compared to 3 tonnes/ha under conservation farming and/or water harvesting conditions and 9 tonnes/ha under irrigation. The main irrigated crops are sugar cane, wheat and rice (Table 4 and Figure 7). Other irrigated crops include coffee, bananas, vegetables, citrus fruits, maize and tea. Cotton irrigation has virtually collapsed in the country due to commercial farmers opting for high-value irrigated crops like paprika.
Urban and peri-urban irrigation in Zambia has become increasingly important since 1992. This period coincides with the advent of the most severe drought experienced in southern Africa and the transition from a command economy to a market economy wherein all subsidies on agricultural inputs were removed and the Government’s role in marketing produce completely ceased. The combination of these events led to the failure of most urban and peri-urban people to practise rainfed farming in their remote fields away from town. Furthermore, the privatization of most companies led to massive job losses in towns. To cope with the cost of living, most people started growing irrigated vegetables and fruit trees in backyard gardens and on their smallholdings. Women marketers buy the vegetables and fruits harvested from these gardens. They sell them in urban markets and along streets and shop corridors. This kind of business acts as a socio-economic safety net since it provides women with an opportunity to generate income at the household level. The producers create employment particularly for young people who work in the gardens as well as market the produce. There are, for example, approximately 2 000 ha of such irrigated gardens around Lusaka town.
In smallholder irrigation, the installation of small drains, furrows and micro-basins are activities that men are heavily involved in. Women are mainly in charge of watering the crops as well as weeding or cleaning the conveyance canals. Mainly women and youths operate the treadle pumps. In pressurized systems, men do the changing of lateral lines and operation of the pumps.
The costs of operation and maintenance of irrigation schemes have not been well documented. However, at Buleya Malima, a surface irrigation scheme using furrow and basin systems, each scheme-member irrigating 0.25 ha paid US$58/year as fee. There are 130 farmers in this scheme, which includes a 3.5 ha orchard whose proceeds go towards operation and maintenance.