CC BY
3
UDK 911,5 511. 4 (575)
Jurakulov Kh.J. professor
Department of Hydrometeorology Samarkand State University Uzbekistan, Samarkand
WAYS OF RATIONAL USE OF NATURAL PLAIN LANDSCAPES
Annotation. The study of the landscapes of the Zarafshan Mountains and adjacent plains showed that the natural conditions of the study area are very diverse. Landscape complexes located in different parts of the region differ not only in terms of nature, but also in terms of economic purpose.
Key words: landscape complexes, azonal landscapes, semi deserts, dry steppe, pastures, black saxaul, richter's Circassian, chogon, teresken, izen.
The study of landscapes of Zarafshan mountains and adjacent plains showed that the natural conditions of the studied area are the most diverse. Landscape complexes, located in different parts of the area, differ not only in terms of nature, but also on the economic purpose. These differences are based primarily on the fact that the landscapes of the study area developed under different terrain conditions, both flat and mountainous.
The development of landscapes of the described area, located at different absolute altitudes. This creates different natural zones, such as semi-desert and arid-steppe. In each zone there are landscapes with different economic value. In addition, there are azonal landscapes in plains landscapes, which differ in their moisture conditions. Azonal landscapes differ from other landscapes in their economic value.
Semi-desert landscapes of the plains are located within the Karnab and Jam-Ulus foothill plains at an altitude of 225-280 m above sea level. The main territory of these landscapes is used as year-round pastures. Within the characterized landscapes, ephemeral wormwood and mugwortphytocenoses are developed. Ephemeral Artemisia-junta phytocenoses are the most valuable fodder for Karakul sheep throughout almost the whole year. The basis of the forage balance of the pasture area includes ephemera in spring and summer, and wormwood and ambergrass in autumn and winter. Ephemerals constitute a good understory fodder during early spring grazing, since they are, points out, most supplied with nutrients and less supplied in autumn and winter. This is evidenced by the data given in Table 1._
№ Nutrients Spring Winter
1 Proteins 19,00 5,11
2 Squirrels 13,06 4,31
3 Fats 2,80 1,73
4 Fiber 27,12 40,73
5 Potassium 1,64 0,64
6 Calcium 0,19 0,82
7 Phosphorus 0,39 0,10
He believes that the nutritive value of forage for a given pasture is estimated at 50 fodder units in spring, 30 in autumn and 40 in winter; the nutritive value of ephemerals is estimated at 80 fodder units in spring and 57 in summer. However, the low productivity of natural pastures and large variations in grass yields by year and season depending on weather conditions often create a very tense fodder balance in Karakuli farming and cause low productivity and large wastes of Karakuli herds.
Studies by the staff of the Karnabe Research Institute of Karakul Sheep Breeding have shown that it is possible to significantly increase the productivity of natural pastures in a relatively short time at low cost by sowing fodder plants and such crops as saxaul, raisin, chogon, cherkez, teresken and others. Black saxaul deserves special attention.
Employees of the institute conducted experiments in the Karnabskaya Plain to create forest belts from black saxaul. They showed that forest strips reaching 3.5-4 m in height in 8 years contribute to an increase in relative air humidity, and a soft and stable microclimate is created in the strip zone, favorable for growth and development of wormwood-ephemeral vegetation. Yield of fodder on pasture on the leeward side of saxaul strip at a distance of 100 m from it increases by 25%. Even in a low-yielding year, the fodder mass of ephemerals turned out to be 14-18% higher than in the open pasture. Sheep eagerly eat black saxaul all year round, and on days of strong winds and bad weather, the strips serve as a place of shelter for sheep.
Long-term studies of the staff of the Scientific-Research Institute of Karakul Wildlife and Desert Ecology of Uzbekistan have shown that artificial pastures created from a mixture of different species and life forms of natural plants (black saxaul, rhizobium cherkez, chogon, teresken, izen and others) have high and stable forage yields, providing a full-grown year-round grazing, feeding and keeping sheep. Yields of artificial pastures in wormwood-ephemera semi-desert are 14-20 cwt/ha of air-dry mass. Part of the landscapes within the semi-desert zone (Ulus foothill-desert plain) is used for bogara. In terms of precipitation availability this area is included in the zone of semi-sufficient bogara, where 320-372 mm of precipitation falls. Atmospheric precipitation varies greatly from year to year. In this connection grain crops yield is unstable and fluctuates from 2 to 5 c/ha. Therefore, for rational use of rainfed lands it is advisable to create forest shelter belts. Protective effect of forest belts on rainfed lands consists in the fact that in winter time of the year forest plantations weaken wind speed, favoring preservation of snow cover. In summer, forest belts weaken the speed of the wind "afghans" blowing from the south, thereby contributing to the accumulation of moisture in the soil. As a result, the most
favorable conditions for growth and development of grain crops are created, and thereby forest plantations contribute to increased grain crop yields. According to the Institute of Grain of Uzbekistan, forest strips on rainfed areas in some years increase yields by 3-4 cwt/ha.
Crop rotation systems are of great importance for moisture conservation in rainfed soils. Here it is recommended to create a five-field row crop rotation. Alfalfa for hay and cucurbits (watermelons) can be grown in tilled crops. Yield of cucurbitaceous crops is 80-100 cwt/ha. It should be noted that the territory of Ulus landscape is the most promising area for irrigated land development. The Yangiaryk diversion canal is laid here for further land development. In addition, within the studied landscapes of semi-desert zone, there are interstitial pressure waters (Nagornaya) with a temperature of 45 °, currently used to treat patients with rheumatism, osteochondrosis. It should be noted that the population's need for treatment with this water is huge. Therefore, to use these interstitial waters for treatment of patients it is necessary to expand the hospital area and increase the number of beds. To improve the recreation of patients, it is necessary to expand the area of green spaces around the hospital.
Dry-steppe landscapes cover the territory of the foothill plain, located in the foothills of Zirabulak-Ziadi, Karatepin and Chakylkalyan mountains at an altitude of 285-700 m. It should be noted that the main part of these landscapes is used as pastures. This is particularly characteristic of landscapes located on the foothill plains of the Zirabulak-Ziadi Mountains and the northern and southern slopes of the Karatepe Mountains. The surface structure of piedmont plains located around the Zirabulak-Ziadi mountains is characterized by dissected relief. Outcrops of bedrock with light coarse-skeleton sierozem are observed here. Vegetation cover is represented by ephemerals, wormwood, and kozikulak. The landscape is used as spring, autumn and winter pastures.
As is known, in the foothills there is usually an acute shortage in fall and winter pastures. Spring plants like rang, congurbash and other ephemeroids and ephemera are predominantly developed. The topsoil is firmly bound by the strong turf of rang and congurbash. Strong sod is one of the reasons why shrubs and semi-shrubs die out in the foothills. Artemisia, a valuable winter fodder, has survived in only a few places. Thus, spring and summer pastures are abundant in the foothills, lacking in fall and winter pastures.
Having studied the peculiarities of foothill landscapes, the researchers of the Scientific-Research Institute of Karakul Sheep Breeding and Desert Ecology of Uzbekistan (Golovchenko, 3;) suggested creating here powerful forage grounds for the autumn-winter season. For this purpose, it is necessary to sow seeds of semishrubs and shrubs consisting of wormwood, izeny, keireuk and kandym. In 2-3 years the yield of fodder crops will increase 2-3 times. This means that the number of sheep per every 100 hectares of pasture land will increase several times (Gaevskaya, 2).
It should be noted that some landscapes of foothill plains are subject to irrigation. Such landscapes are found in the Pridargomskaya foothill plain, located on the northern slope of the Karatepe Mountains. The slopes from the foot of the mountains to the valleys ensure good surface runoff. When irrigating the lands, the hydrogeological and meliorative conditions will be favorable everywhere due to the great depth of groundwater. Some parts of landscapes of foothill plains suitable for irrigation are currently in a neglected condition. In order to raise productivity of these landscapes, it is necessary to start struggle against surface and gully erosion. For this purpose, the following is recommended: against surface linear or planar erosion on soils with thick low-grained layer it is necessary to carry out deep plowing (up to 35-40 cm), contributing to cessation of surface runoff of atmospheric precipitation. Within this landscape, gullies are widely developed, especially near the Dargom canal. To stop the development of ravines, it is recommended to create forest strips, and fast-acting ravines should be secured with engineering structures.
It should be noted that part of the landscapes of the foothill plains is used for bogara. Such landscapes are particularly well developed within the western and southern extremities of the Karatepe Mountains. The typical sierozem soils available here have a rather thick transverse horizon with humus content of 2.2%, phosphorus 0.16-0.17%. These soils are quite fertile by their physical and chemical composition and can be used for various agricultural crops. Currently they are used for bogara. The main activities here should be directed to the conservation of moisture. For this purpose it is necessary to plow in autumn. Autumn plowing preserves more moisture, the physical properties of the upper horizons are improved, more nutrients are accumulated and so on. This landscape is suitable for irrigation and for this purpose the Yangiaryk canal - the outflow of the Zarafshan River - is laid.
Azonal landscapes. Are located within the first, second, third and partially the fourth above floodplain terraces of the left bank of the river Zarafshan and the right bank of the river Kashkadarya from 225 to 700 m absolute height. At present, the described landscapes are fully developed and used for irrigated agriculture.
Landscapes of terraces of Zarafshan and Kashkadarya valleys as a result of centuries of human economic activity are strongly changed and transformed into oasis landscapes. Artificial irrigation of the landscape has been carried out for more than 3,000 years. The centuries-old artificial irrigation in the Zarafshan valley has led to the formation of a new quite powerful (1-2 m) agro-irrigation horizon. The waters of the Zarafshan river contain a lot of nutrients, both in solid and soluble forms. According to V.A. Molodtsov's calculations, from 10.8 to 17.9 g of suspended solids are brought to 1 ha of irrigated field, which is an annual gain of 0.8-1.3 mm in irrigation sediments. It should be noted that the landscapes located on the first, second, third and fourth above floodplain terraces are drained, with irrigated loamy and sandy loam meadow and meadow-
marsh soils. These soils contain 1.4%-2.5% humus, 0.072-0.15% nitrogen, 0.110.13% phosphorus, 5.58-6.08 mg absorbed potassium and 2.46-2.63 mg magnesium (per 100 g of soil) in the arable horizon. Therefore, the landscapes of these lands have an important economic value, the main massifs of cotton and other agricultural crops are located on them.
Landscapes do not require special hydraulic reclamation. However, not all farms have introduced crop rotation, in most cases, cotton is planted continuously for a long time, which leads to soil impoverishment, disturbance of structure, manifestation of diseases and pests of crops. Introduction of cotton-corn-alfalfa crop rotation will help to eliminate these phenomena, replenish soils with nutrients, make it possible to raise the cotton yield and fully provide livestock with fodder.
It should be noted that downstream of the Zarafshan river within the landscapes of terraced plains begins to increase soil salinization and in the area of Kattakurgan. Salinization has sulfate-chloride character. The main reason of salinization of soils is close groundwater occurrence. In order to increase the depth of groundwater occurrence it is necessary to build a collector-drainage network. To provide water for irrigated lands in the lower part of Zarafshan valley (Kattakurgan, Narpai districts) the Kattakurgan water reservoir with volume of 840mln m3 of water was constructed here.
Forests and bushes cover the landscapes located in the floodplain of the Zarafshan river. These landscapes are mainly occupied by riparian forests. The type of tugay vegetation combines not only woody, but also herbaceous and shrub communities of river valleys, closely linked in their origin with the development of ecological conditions of these valleys. Genetically related and ecologically close communities of riparian type differ in structure and features of edificators. This allows us to divide them into three groups of formations, such as tree-shrub riparian, shrub-tugay and herb-tugay. All these three species developed within the floodplains of the Zarafshan river valley have been sharply reduced in recent years.
Land previously occupied by tugai, are developed for agricultural crops and allocated for the construction of houses. In this regard, in recent years, the area occupied by tugai landscapes is sharply reduced. Following the reduction of the area of tugai forests, the number of Zarafshan pheasant decreases. In order to preserve the number of pheasants in the Zarafshan river valley the Zarafshan reserve was established in 1979. However, the area of this reserve is too small. In the future it is necessary to expand the area of tugai landscapes. In addition, tugai landscapes are a great place for recreation. Shady places and river water make it possible to use the riparian landscape for the organization of recreation areas. On the use of riparian landscapes as recreation areas, some work has been done. Near Chupanata and Akdarya bridge on floodplains of the river Zarafshan built two artificial lakes - "Light Lake" and "Seven Lakes", where the population of the city of Samarkand on Sundays spend their time (Jurakulov X. et al. 2022)
References:
1. JurakulovKh.: "Regularities of differentiation of landscapes of Zarafshan mountains and adjacent plains" Samarkand 2022
2. Gaevskaya L.S. "Pastures of deserts and semi-deserts of Uzbekistan", Tashkent: Fan, 1975;
3. Golovchenko S.G. "Foraging in the foothills". - Tashkent, 1962, p.168.
