Irrigation and land degradation: implications for agriculture in Turkmenistan, central Asia

Journal of Arid Environments (1997) 37: 165–179

Irrigation and land degradation: implications for agriculture in Turkmenistan, central Asia

Sarah L. O’Hara Sheffield Centre for International Drylands Research, Department of Geography, University of Sheffield, Sheffield S10 2TN, U.K. (Received 8 July 1996, accepted 27 September 1996) Agriculture in Turkmenistan is almost entirely dependent on irrigation. Expansion of the irrigation network, particularly since the late 1950s, has significantly increased the country’s agricultural output, especially of cotton. While problems of waterlogging and salinisation of Turkmenistan’s irrigation systems have been reported in the past, detailed information has only recently been readily available to western researchers. Data from the mid-1980s onwards indicates that there has been a significant increase in the area of land where the water table is less than 2 m below the surface and more and more land is becoming saline. Declining soils and water quality has significant implication for future agricultural development and could thwart Turkmenistan’s plans to diversify its agricultural base from one almost entirely dependent on cotton to one that will enable the country’s food requirements to be met. ©1997 Academic Press Limited Keywords: agriculture

Turkmenistan;

irrigation;

salinisation;

water

logging;

Introduction The concentration of salts in the surface and near-surface zones of soils is a major process of land degradation, with globally an estimated 953 million ha of land salt effected (Szabolcs, 1987). Although soils in many parts of the world are naturally saline, human-induced salinisation, often termed ‘secondary salinisation’, is widespread and in many areas, particularly dryland environments, is the focus of considerable concern. Grainger (1990), for example, believes that it is one of the main causes of desertification, while Rhoades (1990) concluded that in some countries the salt problem poses a serious threat to the national economy. Irrigation systems are particularly prone to salinisation and it is considered to be one of the main causes of falling crop yields and the loss of land from production (Thomas & Middleton, 1993). On the global scale, a FAO report stated that ‘Nearly 50 per cent of the irrigated land in arid and semi-arid regions have some degree of soil salinisation problems’ (Abrol et al., 1988) while Szabolcs (1987) estimated that about 10 million ha of irrigated land is abandoned every year because of salinisation and alkalisation. 0140–1963/97/010165 + 15 $25.00/0/ae960238

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There is a large body of literature on the causes and effects of secondary salinisation (e.g. Rhoades, 1990; Barrow, 1991; Thomas & Middleton, 1993). Common causes include inappropriate cultivation techniques and changes in vegetation type. Problems of salinisation are particularly associated with irrigation schemes and are usually a result of seepage from supply channels, over-application of water, poor drainage, poorly levelled land, the application of water with too high a salt/alkali content, and insufficient application of water to leach salts (Barrow, 1991). Both salinisation and waterlogging can be prevented through good irrigation design and practice (Barrow, 1991), but when salts do accumulate in the upper part of the soil profile it is necessary to leach them by placing more water on the land than is necessary for plant growth; excess water percolating through the soil draws salts down from the surface. However, unless this surplus water is removed from the land it will increase ground-water levels which can in turn increase waterlogging and salinisation (Johnson & Lewis, 1994). Irrigation systems are particularly vulnerable when ground-water rises to within 1·5–2·5 m of the surface and can be evaporated or transpired causing salts to accumulate. Salt accumulation has a direct impact on both soils and vegetation. In soils, salts reduce pore space and inhibit its ability to hold air and nutrients. Moreover, variations in the balance between sodium and calcium plus magnesium can effect soil structure (Barrow, 1987). Vegetation and crops grown on salt-effected soils or irrigated by saline waters generally display reduced growth and lower yields as the plant expends more energy trying to extract water from the soil and to survive under stressed conditions (Rhoades, 1990). The degree to which salt effects vegetation is dependent on the tolerance of the individual plant to salt and the stage of its growth; the most sensitive period being during the seedling stage (Rhoades, 1990). The widespread salinisation of irrigation systems in the Central Asian Republics (CARs) of the Former Soviet Union (FSU) is an oft-quoted example of how irrigation can directly and indirectly degrade land (Micklin, 1988; Smith, 1992; Glantz et al., 1993). Details of the extent and severity of the problem, however, have tended to be somewhat general as until recently relatively little information has been widely available outside the FSU. With the collapse of the Soviet Union and the emergence of newly independent sovereign states the situation has changed and areas such as the CARs, that were once difficult to access, are becoming more open to western researchers. Moreover, widespread concern regarding the rapid decline of the Aral Sea and its immense socio-economic and environmental impacts on the CARs has resulted in a considerable influx of government and non-governmental organizations. A number of large-scale, internationally sponsored projects have been established (see e.g. UNEP, 1992; World Bank, 1993; WARMAP, 1995), and the information they have collected over the last few years forms a comprehensive and easily assessable database. These data provide detailed county-level information on a range of economic, social and environmental factors. This paper focuses on problems of soil degradation, in particular waterlogging and salinisation associated with irrigation systems, in Turkmenistan, outlining the nature and extent of the problem and assessing its implication for the future economic development of this state.

Turkmenistan Turkmenistan is the southernmost of the republics of the FSU. The country is bordered to the west by the Caspian Sea, to the south by Iran and Afghanistan, to the east by Tadjikistan and to the north and north-east by Kazakstan and Uzbekistan (Fig. 1). It covers an area of c. 480,000 km2 of which 75% comprises the Kara Kum Desert (Babaev, 1994). The country’s small population, c. 4·1 million (Ballard, 1994), is concentrated in a thin strip of land along the foothills of the Kopet Dag and in areas

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Figure 1. Turkmenistan, showing the five viloyats and the main areas of irrigation.

where the land is irrigated. The country is divided into five viloyats: Balkan, Akhal, Mary, Lebap and Dashouz (Fig. 1) which correspond to former soviet oblasts (provinces). Most of Turkmenistan comprises lowlands, mountains being confined to the southern and western parts of the country. It lies within the temperate desert zone (Babaev, 1994) and has a marked continental climate with hot, dry summers and cool, humid winters (Orlovsky, 1994). Average annual rainfall varies from 90 mm in Dashouz to nearly 400 mm in the south-west highlands of the Kopet Dag, but in much of the country rainfall is less than 200 mm year–1. Average temperatures are high, varying from 12–18°C. The coldest months are December to February with temperatures frequently falling below 0°C, and the hottest months June to August when temperatures often exceed 45°C (Orlovsky, 1994). The hydrological network is weakly developed and all major sources of water rise outside the country’s borders. The headwaters of the Amu Darya, the largest river in central Asia, is in the Pamirs to the east and the river enters and leaves Turkmenistan via Uzbekistan. It displays two periods of peak discharge, one during the spring, associated with winter rains, the other later in the summer when snow and ice melt increases flows. Other rivers, the Atrek, Murgab, and Tedjen, all rise in the mountains to the south, the former flowing into the Caspian Sea while the latter two drain into the Kara Kum Desert. Although small when compared to the Amu Darya, these rivers nevertheless prove an important source of water and have long been used by people occupying the region (Lewis, 1966). Fed by winter rains and snowmelt they only have one period of peak discharge during the spring. In addition to these rivers there are a number of smaller intermittent rivers and springs, most of which cease to flow during the summer. Despite its aridity, the area that now comprises Turkmenistan has a long history of

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agriculture and settlement (Masson, 1961; Harris et al., 1993). As agriculture is entirely dependent on irrigation, access to water is essential and control of the country’s limited water resources has long been associated with economic prosperity. Although the soils are fertile and capable of supporting a diverse range of crops, the Russians who conquered these lands in the late 1880s were more interested in the region’s ability to produce cotton, and between 1887 and 1914 the amount of land sown to cotton increased from 1000 to 62,000 ha (Table 1; Curzon, 1890; Zaharchenko, 1990). Although cotton production decreased during the Bolshevik Revolution, the Soviet administration soon made clear its intentions regarding cotton production and, in November 1920, Lenin issued an edict that the cotton industry in central Asia was to be reconstructed. As Moscow demanded increased cotton output, more and more land was given over to its production. This was achieved through increasing the actual amount of land cultivated and at the expense of other crop types, particularly grain (Table 1). The massive expansion in the area of land cultivated was made possible by increasing the country’s irrigation network, a process that started during the tsarist period. In 1891 the tsarist government developed an additional 33,000 ha of irrigated land in the Murgab Oasis while between 1884 and 1915 the amount of land irrigated in the Tedjen Oasis increased from 47,000 to 98,000 ha (Zaharchenko, 1990). The Soviet administration also gave priority to increasing the irrigation system of central Asia and in May 1918 the Council of People’s Commissars allocated 50 million roubles for the development of an additional 550,000 ha of land (Zaharchenko, 1990; Gleason, 1991), while at the first all-Turkmenian Soviet Congress held in February 1925, resolution number four called for the development of irrigation in southern Turkmenistan (Zaharchenko, 1994). But with limited indigenous water supplies it was recognised that if there was to be a substantial increase in the amount of land irrigated water would have to be transferred to the region. Using ideas originally suggested by Russian engineers, plans were made to divert water from the Amu Darya westwards across southern Turkmenistan. Construction of the Kara Kum Canal was begun in Table 1. Variations in the area of land irrigated, and sown to cotton and wheat 1884–1994

Year

Area irrigated (ha ×103)

Area sown to cotton (ha ×103)

Area sown to grain (ha ×103)

1884 1914 1917 1922 1940 1950 1958 1965 1970 1980 1988 1994

63·5 168·0 104·9 220·0 360·0 348·81 393·63 521·44 668·06 964·01 1318·37 1453·96

1·0 62·0 1·52 10·0 150·0 153·0 222·0 257·0 397·0 508·0 636·0 579·0

– – 77·6 121·0 183·0 128·0 71·0* 133·0 84·0 132·0 164·0† 457·3

*Figure for 1960; †figure for 1986. Source: Curson, 1890; Bestnik, 1923; Zaharchenko, 1990, Craumer, 1992; WARMAP, 1995.

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1954 and completed in 1986 (Shabad, 1987). Today it transfers 12 km3 of water along its 1400 km length allowing an additional 716,000 ha of land to be cultivated (Giles, 1994).

The irrigation network in Turkmenistan Over the tsarist and Soviet periods the area of land irrigated in Turkmenistan increased from 63,500 to 1·45 million ha (Table 1). The most significant growth period occurred after 1958 and was largely due to the construction of the Kara Kum Canal (Table 1). The main source of water for irrigation is the Amu Darya, and c. 1·35 million ha of land is supplied with water from this river, the balance coming from rivers that rise in the Kopet Dag with lesser amounts of ground-water also used. Irrigation is largely confined to the eastern part of the country and along a thin tract of land adjacent to the Kara Kum Canal (Fig. 1). In the westernmost viloyat of Balkan, for example, only c. 42,500 ha of land are irrigated (Table 2). In Turkmenistan as a whole water is distributed by an extensive network of canals totalling more than 30,000 km in length, the majority of which are both open and unlined. Only 14·7% of all irrigation canals are lined although in Dashouz and Lebap the figure is 0·6 and 1·2%, respectively, while in Akhal it is 37% (Table 2; Zaharchenko, 1990). Actual water losses from canals varies across the country and depends in part on the type of material in which they are incised. Figures for part of the Kara Kum Canal, for example, indicate that losses range between 80 and > 360 1 s–1 km–1 (Saparov et al., 1970). Government figures indicate that losses from the conveyance system amounts to 6·3 km3 per annum, or 28% of the total amount of water used for irrigation. Although this figure appears quite high, when compared with other countries where agriculture is largely dependent on irrigation, it is evident that losses are relatively small. Thus while the conveyance system in Turkmenistan has an average efficiency of 72%, in India efficiencies vary from 50 to 70%, in Egypt it is about 66%, while in Turkey some conveyance systems are only 26% efficient (Bos, 1976). Ninety-nine percent of the land is irrigated from the surface with furrow irrigation predominating (WARMAP, 1995). Drip irrigation has only recently been introduced, mainly on small experimental farms close to the capital, Ashgabad. Like the conveyance system, considerable amounts of water are lost to evaporation and seepage and account for 5·7 km3 of water per annum with the average efficiency for the country being 67%. Total efficiency of the country’s irrigation system is approximately 45%, although it is worth noting that the amount of water required to produce one tonne of cotton is almost three times greater in Turkmenistan than for Israel (O’Hara, unpub.). The level of in-field drainage to remove excess water is relatively low. Only 58·4% of irrigated land in Turkmenistan is drained, although there is considerable variation between viloyats. In Balkan for example the figure is as low as 8·9% while in Lebap it stands at over 81% (Table 2). The low level of drainage in Balkan is interesting as much of this land has only recently been cultivated. This suggests that recent extensions to the irrigation system have been made without the emplacement of drainage. About 20% of drains are closed, which although less efficient than open drains take up less land, and when functioning correctly require considerably less maintenance. Giles (1994), however, reported that none of the closed drainage systems he inspected in 1994 were operational and that the installation of new closed drains had been stopped. The failure of these closed systems suggests that an additional c. 167,000 ha of land are without effective drainage and that almost 54% of the irrigation system in Turkmenistan could be prone to rising ground-water levels.

42,445 363,399 429,611 258,472 360,034 1,453,961

Balkan Akhal Mary Labap Dashouz Total

1021·7 8884·5 7546·7 4876·1 8039·6 30,378·6

Length of canal network (km) 380·0 3267·1 717·7 77·0 48·2 4490·8

Canal network lined (km)

Source: Giles, 1994; Rothwell, 1994, Zaharchenko, 1994.

Area of land irrigated (ha)

Viloyat 37·3 37·0 9·6 1·2 0·6 14·78

3793 179,604 233,897 209,526 222,916 849,736

Percent of network lined Area drained (ha)

Table 2. Details of Turkmensistan’ irrigation network

8·9 49·4 54·4 81·1 61·9 58·4

Percent of land drained

3793 50,076 49,623 3976·8 23,777 167,037

Area with closed drainage

170 S. L. O’HARA

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Quality of irrigation water

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In general, water used for irrigation rarely has salinity levels in excess of 2 g 1–1, although the actual salt content does vary between years (Fig. 2). So, for example, in 1990 when flows in the Amu Darya were high, 96% of all land was irrigated with water containing less than 1 g 1–1 of salt. In 1992, however, the figure fell to 50% and it was necessary to irrigate a small amount of land with water containing more than 2 g of salt per litre (Ministry of Amelioration and Water Supply, 1988–1993). Variations in the quality of irrigation water occur across the country. In Mary, for example, water is much more likely to have a salt content of 1–2 g 1–1 compared with Akhal and Lebap where the quality is generally better. Salinities may reflect the distance that water is transferred from source as well as the nature of the canals forming the distribution system. In Labap, for example, water is drawn directly from the Amu Darya, while in Mary and Akhal water is transferred over a considerable

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distance along the Kara Kum Canal. However, despite being closer to the main source, water used to irrigate the lands in Mary are more saline. Higher salinities could be due to the material in which canals are constructed being more saline or due to greater evaporation from the canals and the concentration of salts. Problems of waterlogging High ground-water levels pose a serious threat to agricultural lands and as noted are considered to be a major cause of salinisation. Figure 3 shows ground-water level by viloyat for Turkmenistan for the period 1986 to 1992. It is evident from these data that

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Figure 3. Variations in ground-water levels (m below surface) in irrigated areas by viloyat and for Turkmenistan as a whole, 1986–1992 Source: Ministry of Amelioration and Water Supply, Government of Turkmenistan (1988–1993).

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most of the country’s irrigated land experienced increasing ground-water levels over this period. The amount of land where ground-water levels were less than 2 m below the surface increased by over 285,000 ha while the percentage of total agricultural land in this category rose from 41·4 to 52·7%. The data for individual viloyat show that although all parts of the country have seen increases in ground-water levels, the amount of land affected differs considerably. In Akhal, for example, an additional 22,370 ha of land had ground-water levels less than 2 m below the surface while in Lebap the figure rose by nearly 121,500 ha. The data from individual viloyats reveals that the percentage of cultivated land with ground-water tables less than 2 m increased from between c. 7 to over 41%. The most severely effected area is Lebap (Fig. 3). The amount of land with water tables greater than 4 m below the surface also rose during the 7-year period by 13,600 ha. However, most of this increase is accounted for by the expansion of the irrigation network in Balkan with the addition of an extra 13,000 ha of land in 1992. In those viloyats where ground-water levels of less than 4 m are found, a general decline in the areas of land was noted. The combined total of water losses in the conveyance and in-field systems is c. 12·4 km3 , almost half the total water used by the country. Most of this water is lost through seepage and has resulted in large areas of land adjacent to canals being waterlogged. Losses from the Kara Kum Canal are particularly high and a vivid impression of its effect can be gained from the air where one can clearly observe numerous depressions filled with seepage water easily identified by prolific weed growth. Some of these water bodies cover an extremely large area and have resulted in significant amounts of agricultural land being lost. Data on ground-water salinity levels for 1992 are shown in Table 3.. Less than 10% of the country’s ground-water has a salinity level less than 1 g l–1, equivalent to the highest quality irrigation water in Turkmenistan (Giles, 1994). Overall, most groundwater has salinity levels between 1 and 3 g l–1 with approximately 15% registering values between 3 and 5 l m–1 1 and nearly 27% having salinities > 5 g m–1. Groundwater is most saline in the Akhal viloyat with 37% having more than 10 grams of salt per litre, while Labap and Dashouz have ground-waters with generally low saline levels (Table 3). Soil salinity Turkmenistan’s Ministry of Amelioration and Water Supply are charged with collecting information on soil salinity levels. A four-fold classification is used Table 3. Ground-water salinity (g l–1) in irrigated areas by viloyat and for Turkmenstan as a whole, 1992

Ground-water quality (g l–1) Viloyat Balkan Akhal Mary Lepab Dashouz Total

<1

1–3

3–5

5–10

10–25

>25

Total

3090 31,441 12,212 63,475 32,255 142,473

12,806 117,299 230,016 155,375 174,750 690,246

13,568 45,581 90,150 24,805 53,578 227,682

10,373 33,978 59,849 10,685 49,250 164,135

1529 89,373 34,697 3797 32,619 162,015

1079 45,727 2687 335 17,582 67,410

42,445 363,399 429,611 258,472 360,034 1,453,961

Source: Ministry of Amelioration and Water Supply, Government of Turmenistan; Giles, 1994.

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delimiting soil salinity as non-saline, weak, medium, strong and very strong dependent on the percentage of toxic salt in dry soils (Fig. 4). Soil salinity data for the period 1987 to 1992 for the five viloyats and Turkmenistan as a whole are shown Fig. 4. These data indicate that the amount of salt within the upper metre of soil has increased markedly over the 6-year period. The total amount of soils that suffered from strong to very strong salinities increased by nearly 80,000 ha accounting for over 15% of the total agricultural land in 1992. Over the same period the area of land where soils were nonsaline decreased from 10·5 to 4·7% of the total land area cultivated (Fig. 4). Two viloyats, Balkan and Dashouz, have particularly saline soils. In the former there does appear to have been a significant drop in the amount of land that is strongly saline, from 40% in 1990 to less than 20% in 1992, but this merely reflects the recent

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Figure 4. Soil salinity (dsm ) in irrigated areas by viloyat and for Turkmenistan as a whole, 1987–1992. Source: Ministry of Amelioration and Water Supply, Government of Turkmenistan (1988–1993); Giles, (1994).

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expansion of agriculture in the region. Given that the south-western part of Balkan viloyat is underlain by late Quaternary sediments deposited when the Caspian Sea covered this region, it is likely that these newly farmed soils could become saline within a very short period of time due to incipient sediment salinity. Certainly the increase in weak and medium saline soils in the region between 1990 and 1992 suggest that this process is already underway. There are no non-saline soils in the Dashouz viloyat and the amount of weakly saline soils decreased by over 45,000 ha between 1987 and 1992. Over the same time interval the level of soils classified as strongly saline increased from 16·2% to 25·7% with an additional 30,000 ha of land falling into this category. One viloyat, Lebap, does show an interesting difference to other areas with the amount of land having strong and very strong saline soils falling from 29,700 to just over 15,000 ha. Over the same period, however, the amount of non-saline soils declined from c. 28,000 to 8000 ha. While these data indicate an overall reduction in the amount of highly saline soils it is possible that soils are becoming too saline and are no longer suitable for agriculture. The viloyat with the most non-saline soils is Mary which in 1992 stood at over 47,000 ha, but even here despite a slight increase in the area of soil classified as non-saline the actual percentage of the total amount of land cultivated in the region fell from 12 to 11%.

The state of the land A 1992 survey of the reclamation status of land under irrigation in Turkmenistan indicated that only 15·9% of the total land area was classified as good for agricultural use, with 39·6% deemed satisfactory, while 44·5% of land was considered to be unsatisfactory because of the effects of high water tables and/or high soil salinity (Giles, 1994). The figures represented here, however, do not include the amount of land that is lost to agriculture. According to Zaharchenko (1990) the amount of land being lost or affected by seepage and salinisation has increased from 11,000 ha in 1959 to over 46,000 ha per annum by 1970, a figure that has remained at this level until at least the late 1980s. It is worth noting that there are significant differences in reported ground-water and soil salinity levels for the periods before and after independence. During 1989 and 1990, for example there is an apparent decrease in ground-water levels when compared to the previous 3 years. The figures for 1991 and 1992, however, indicated a marked increase in ground-water levels. A similar trend is noted for soil salinities. While ground-water levels and soil salinities may have varied over this period it is possible that changes in the reporting procedure account for this apparent improvement in land conditions. Indeed, the 12th and final 5-year plan (1986–1990) called for improvements in irrigation systems and better use of available water resources (Micklin, 1987). The improved state of the soil could be due to better land management practices immediately prior to the break-up of the Soviet Union with a subsequent decline, or could be the result of a degree of flexibility in the reporting of information.

Implications for agriculture Agriculture is a vital component of Turkmenistan’s economy, currently employing more than 40% of the country’s workforce (Ballard, 1994). The Soviet policy of ‘cotton at any price’ which turned the region into a series of huge cotton plantations meant that at independence the country was unable to meet its food requirements. In 1994 the Halk Maslahey, Turkmenistan’s people’s council, approved the ambitious

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‘Ten Years of Prosperity’ plan which as one of its aims set targets for increased agricultural output. To achieve food self sufficiency by the year 2002, it is intended to increase the output of grain by 340%, vegetables by 195%, and dairy and meat production by 290%. Moreover, the plan calls for a 65% increase in cotton production. Under a ‘business as usual’ scenario these targets can not be met (O’Hara, unpub.), but with an increase in crop yields and more efficient irrigation it is possible that the required level of production could be attained, although it is unlikely to be within the time frame of the plan. A major factor determining Turkmenistan’s agriculture in the future will be the extent to which soils suffer from waterlogging and salinisation. These factors will not only influence yields, but also the type of crops that can be grown. The effect of soil salinities on a range of crops currently grown in Turkmenistan are shown in Table 4. The most salt tolerant are winter barley, cotton and winter wheat; rice, squash, tomatoes and alfalfa can tolerate weak to moderate levels of salinity while other crop types such as carrots, potatoes, and most fruits are extremely sensitive to salt. Given present levels of salinity, many parts of the country will be limited to growing crops more tolerant to salt, and even then yields will not be the maximum possible. Moreover, land suitable for growing fruit and vegetable is limited and according to the data presented here is declining rapidly. It will be necessary to use more saline lands if production is to increase, but as this will result in lower yields, more and more land will have to be cultivated. While Turkmenistan has a vast area of land suitable for cultivation it does not have sufficient water to irrigate these lands (O’Hara, unpub.) which will limit any future expansion of the country’s agricultural system. Yields can be improved by leaching soils, although again this will require more water. Moreover,

Table 4. Variations in yield with soils of different salinities for selected crops grown in Turkmenistan

Nonsaline

Weak

Moderate

Strong– very strong

2 Ece 4 Ece 6 Ece 8 Ece 12 Ece 16 Ece ds m-1 ds m-1 ds m-1 ds m-1 ds m-1 ds m-1 Winter barley (Hordeum vulgare) Cotton (Gossypium hirsutum) Winter wheat (Tritcum aestivum) Rice (Oriza sativa) Maize (Zea mays) Squash (Cucurbita pepo melopepo) Tomatoes (Lycopersicum esculenthum) Potatoes (Solanum tuberosum) Pepper (Capsicum annuum) Carrot (Daucus carota) Turnip (Brassica rapa) Alfalfa (Medicago sativa) Apricot (Prunus armenica) Grapes (Vitus sp.) Plum, prune (Prunus domestica) Source: FAO (1992).

100 100 100 100 96 100

100 100 100 88 72 100

100 100 100 63 48 87

100 94 86 38 24 68

80 71 57 0 0 29

60 47 29 0 0 0

100 96 93 86 90 100 90 95 91

86 72 65 58 72 86 43 76 55

67 48 37 30 54 71 0 57 20

48 24 8 1 36 57 0 38 0

10 0 0 0 0 29 0 0 0

0 0 0 0 0 0 0 0 0

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with large areas of land undrained or with drainage that does not function there is a danger of ground-water levels increasing and more land being lost to waterlogging and salinisation. The trend towards higher ground-water levels and more saline soils over the late 1980s early 1990s does not bode well for Turkmenistan. It if continues the country will be unable to grow certain important basic food products, and will be limited to growing crops such as wheat, barley and cotton. But even these crops will suffer from salt effects and have reduced yields. The other factor that must be considered is the quality of irrigation water. Although many crops are tolerant to waters with low salinities (Table 5), others are not. Again fruit and vegetables are particularly sensitive to salt content and show a reduced yield when water contains more than 1 g l–1 of salt. Although irrigation water for most of Turkmenistan is of a relatively good quality, salt content does vary from year to year and will have the effect of changing crop yield. This could cause problems in determining total output for the country on a short-term basis. Furthermore, should there be increased use of water upstream of Turkmenistan, water quality could decline in the future and have important implications for Turkmenistan’s agricultural potential. Unless measures are taken to improve the condition of Turkmenistan’s soils, the potential for increased agricultural output will be limited. The country is far from being self-sufficient in respect to food and is already falling behind on the targets set by the ‘Ten years of prosperity’ plan (O’Hara, unpub.). Indeed there has been a noticeable decrease in crop yields during the first years of independence and while these may reflect reduced availability of agricultural inputs such as fertilisers and pesticides (Pickles et al., 1995) it could also be a result of increased land degradation. Improved irrigation efficiencies and better drainage would not only improve soils but also allow more land to be cultivated. The costs will, however, be substantial and recent estimates suggest that rehabilitation of the country’s irrigation system will be, at Table 5. Variations in yields with irrigation water of different salinity for selected crops grown in Turkmenhistan

0·5 1 1·5 2 3 4 mg l–1 mg l–1 mg l–1 mg l–1 mg l–1 mg l–1 Winter barley (Hordeum vulgare) Cotton (Gossypium hirsutum) Winter wheat (Tritcum aestivum) Rice (Oriza sativa) Maize (Zea mays) Squash (Cucurbita pepo melopepo) Tomatoes (Lycopersicum esculenthum) Potatoes (Solanum tuberosum) Pepper (Capsicum annuum) Carrot (Daucus carota) Turnip (Brassica rapa) Alfalfa (Medicago sativa) Apricot (Prunus armenica) Grapes (Vitus sp.) Plum, prune (Prunus domestica) Source: FAO (1992).

100 100 100 100 100 100

100 100 100 100 92 100

100 100 100 94 78 100

100 100 100 80 64 100

100 100 92 52 36 77

93 91 75 24 8 54

100 100 100 98 98 100 100 100 100

100 92 88 82 87 97 83 92 85

90 78 72 65 76 88 54 81 64

79 64 56 48 66 79 25 69 43

55 36 23 15 45 61 0 47 0

32 8 0 0 24 43 0 24 0

178

S. L. O’HARA

a minimum, $800 ha–1 at todays prices (Rothwell, 1994) meaning that the country would have to spend at least $US 1·2 billion. Given that the country has a GDP of about $US 3 billion, the cost of improving irrigation will place a huge strain on the country’s economic resources. An additional problem is also apparent; the decline of the Aral Sea has resulted in vast tracts of the former seabed being exposed. These sediments are enriched with salts, fertilisers and pesticides making a highly potent cocktail hazardous to both humans and the environment. The fine sediments are highly erodible and susceptible to wind erosion, and Micklin (1988) estimated that annually 43 million tonnes of salt are removed from the Aral Sea basin and deposited over an area of 1·5 to 2 million km2, causing considerable damage to farmland. Agricultural regions such as Dashouz lying close to the former shores of the Aral Sea will be particularly affected by salts from this source.

Conclusion The direct and indirect impacts of irrigation on agriculture in Turkmenistan have been immense. On one hand it has allowed large areas of desert to be cultivated and increased agricultural output, albeit of a limited number of crops. On the other hand irrigation systems are poorly designed and inefficient resulting in large tracts of land being salinised and/or waterlogged. The implications for crop production are significant, as yields are not only low but declining. Moreover, with increased tension over water at both a national and international level (Smith, 1992), there is little chance of Turkmenistan developing new agricultural lands. Turkmenistan’s agricultural future does not look promising and unless immediate action is taken, the situation will only get worse. Research for this project was undertaken as part of an ESRC Research FellowshipH53627502095. I wish to thank Chris Knee and Charlotte Grey of Landell Mills for providing access to a series of reports commisioned under the EU TACIS programme, Wierner Schmidt, EU-TACIS office Brussels, for permission to use data collected under the programme and Jaap Sprey at the EU TACIS office in Ashgabad.

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