Jour of adv research in dynamical & control systems, vol. 12, special issue-06, 2020
Fig.-1. Composition of humus and nutrients in soils
Download 422.53 Kb. Pdf ko'rish
|
Ramazonov
- Bu sahifa navigatsiya:
- Fig. 3.
Fig.-1. Composition of humus and nutrients in soils Fig.-2. The composition of the water extract of soils According to the degree of mineralization, groundwater consists of weakly (1,0-3,0 g/l), medium (3,0-10,0 g/l) and highly saline (10,0-25,0 g/l) water. Studies have not established the presence of fresh (1 g/l), very highly mineralized (25-50 g/l) and saturated with salts (> 50 g/l) groundwater. The total amount of salts by dry solids is from 1,520-1,480 to 12,280-17,400 g/l. By type and degree of salinization, groundwater is classified as chloride-sulfate and sulfate-chloride types; slightly, medium and highly saline. The content of readily soluble salts of chlorine and sulfate in the upper horizons of soils varies in different limits. Gray- brown soils are very salinized, where the number of solids in the upper horizons on average ranges from 2,150 to 5,330%, in the underlying horizons it decreases to 1,160-3,715%. The number of absorbed bases in the upper horizons of gray-brown soils is 4,63-7,25 mg/equiv in 100 g of soils, in takir soils 9,52 mg/equiv, sodium, respectively 7,7-16,1% and 5,48-7,35% what to say about salinization of these soils to a large extent. In salt marshes, the total salt content is more than 3% and salt marshes that have preserved ancient genetic traits are called typical salt marshes, and salt marshes can grow here. In appearance and structure, they are divided into the following types: cortical salt marshes, slightly solonetzic, cortical-thin salt marshes and black salt marshes. Such salt marshes are widespread in the Aral Sea region and, by their mechanical composition they are light loamy and subject to very strong salinization. The change in the properties and characteristics of the soil cover of hydromorphic soils under the influence of desertification is closely related to the formation of new agro-irrigation horizons as a result of irrigation, the inclusion of water-soluble small particles and soluble substances with irrigation water, the intensification of eluvial processes as a result of strong moisture, cultivation of plants and agricultural measures. These soils are divided into newly irrigated and old irrigated meadow- alluvial soils. Newly irrigated meadow-alluvial soils differ from old-irrigated meadow-alluvial soils in terms of mechanical composition, variety of horizons, and layered soil profile. The mechanical composition of irrigated meadow-alluvial soils of the Aral Sea region consists of heavy, medium, light loamy, sandy loam, sand, and sometimes clay particles. In old irrigated meadow and alluvial soils, coarse sand particles make up 16,5-34,6%, in newly irrigated meadow and alluvial soils 23,9- 33,8% and 12,4-21,3%, silty particles, respectively, 5,0-10,0% and 4,5-7,8%, physical clay - from 24,6-45,8% to 24,0- 38,5%. The arable horizon of old irrigated meadow-alluvial soils contains 0,965-1,028% humus, the amount of mobile phosphorus on average 15,0-38,0 mg/kg, exchange potassium 84,0-239,0 mg/kg of soil. Newly irrigated meadow-alluvial soils in the arable horizon contain 0,746-1,246% humus 23,0-35,0 mg/kg of mobile phosphorus and 96,0-119,0 mg/kg of exchange potassium. As the data on the content of humus and nutrients show, these soils are low and very low provided with them. In the arable horizon of meadow-takyr soils, the amount of humus is 0,942%, total nitrogen 0,075, downward along the soil profile, the humus content decreases to 0,347%, the number of carbonates is 7,603%. In the lower part of the soil profile, there are rusty brown spots, indicating an ancient and increasing hydromorphism. These soils are mainly heavily salted, and the dry solids content in the upper horizon of residual-bog soils is 2,330-2,730%, in residual-meadow solonchak soils 2,400-5,230%, in semi-hydromorphic coastal solonchaks 5,060-5,790% is contained, the maximum the content of chlorine ion was noted in semi-hydromorphic coastal salt marshes, where its content is 2,970%. According to the chemistry of salinization of the soil, mainly chloride, chloride-sulfate and sulfate-chloride; residual-bog soils, mainly chloride-sulfate and sulfate-chloride, residual-meadow salt marshes - chloride; in semi-automorphic coastal solonchak soils, the salinity type is chloride and sulfate-chloride. Gray-brown, takyr, old and newly irrigated meadow- alluvial soils according to the type of salinity belong to the chloride, chloride-sulfate and sulfate types and according to the degree of salinity - slightly saline, highly saline and very strongly saline (table No. 2).
Soil cover of the aral sea region and change of soil properties under the influence of desertification (on the example of soils of the karakalpakstan region) 625
In particular, the residual-bog soils of the Muynak massif are formed on modern sediments of the lower Amu Darya. In the Kazakdarya massif, residual-meadow solonchaks that are formed on the modern deposits of the Amu Darya and they were formed as a result of the development of marsh soils and subsequently due to salinization are very widespread. According to the mechanical composition, residual-bog soils are medium and light loamy, and in the upper layer of medium loamy soils, sand particles make up 35,3%, dust particles 25,2%, silty particles 7,4% and physical clay 42,2%; in light loamy soils, sand particles make up 33,7%, silty particles 2,3% and physical clay 27,1%. The residual meadow salt marshes in the mechanical composition contain 40,2% of sand particles, 35,2% of dust particles, 7,7% of sludge and 24,0% of physical clay. In terms of mechanical composition, moderately hydromorphic soils mainly consist of sand, where sand particles make up-42,4%, dust particles – 28,0%, silty particles–4,5%, physical clay is – 28,7%. Semi-hydromorphic coastal salt marshes contain 23,5% of sand particles, 49,3% of dust particles, silt – 4,6%, physical clay – 26,2%. In the residual wetland soils of the Aral Sea region in the upper horizon, an average of 1,400-1,540% humus, mobile phosphorus on average 14,0-26,0 mg/kg, exchange potassium 172,0-240,0 mg/kg, carbonates 9,36-10,45%, gypsum 0,013-0,218%. The arable horizon of these soils contains 0,746-1,246% of humus, mobile phosphorus on average 23,0-35,0 mg/kg, exchange potassium in the range of 96- 119 mg/kg. The research results show that the residual meadow solonchaks are low and very low provided with humus and nutrients, so the humus content in the upper soil layer is 0,834-0,850%, mobile phosphorus – 0,904-1,00 mg/kg, exchange potassium - 204-265 mg/kg, the number of carbonates is in the range – 7,565-8,237%, in the semi-hydromorphic coastal salt Jour of adv research in dynamical & control systems, vol. 12, special issue-06, 2020
626
DOI: 10.5373/JARDCS/V12SP6/SP20201072 *Corresponding Author : Bakhtiyor RamazonovichRamazonov Article History: Received: Mar 24, 2020, Accepted: June 27, 2020 marshes gypsum profile is less – 0,019-0,021%. Semi-hydromorphic coastal salt marshes of the Aral Sea zone arose under severe drought. These soils are mainly heavily salted, and the salt content by dry solids in the upper horizon of residual-bog soils is 2,330-2,730%, in residual-meadow solonchak soils 2,400-5,230%, in the floor of hydromorphic coastal solonchaks 5,060-5,790%, the maximum content of chlorine ion was observed in the semi-hydromorphic coastal salt marshes, where its content is 2,970%. According to the chemistry of salinization of the soil, mainly chloride, chloride-sulfate and sulfate- chloride; residual-bog soils, mainly chloride-sulfate and sulfate-chloride, residual-meadow salt marshes - chloride; in semi- automorphic coastal saline soils, the salinity type is chloride and sulfate-chloride. Gray-brown, takyr, old and newly irrigated meadow-alluvial soils according to the type of salinity belong to the chloride, chloride-sulfate and sulfate types and according to the degree of salinity - slightly saline, highly saline and very strongly saline. The capacity of soil absorption and the composition of absorbed cations are considered important indicators that determine the properties and condition of soils, their degree of fertility and productivity, and form a high content of the sum of absorbed magnesium and sodium cations in the soil-absorbing complex. The process of salinization occurs in saline soils; in the subsurface horizon of soils (20-30-70 cm), a brownish-brown, highly compacted horizon forms, which has a negative effect on the normal growth and development of plants. The absorption capacity and the content of absorbed cations in 100 g of soil range from 10-11 to 14- 15 mg/equiv. These indicators in the irrigated soils of the Aral Sea region are 10,85-14,71 mg/equiv in the arable horizon of the old irrigated meadow-alluvial soils and 11,20-15,52 mg/equiv in the newly irrigated meadow-alluvial soils. The number of absorbed bases in the upper layer of residual-bog soils is 10,47-13,32 mg/equiv, in residual meadow solonchak soils – 30,21-38,75 mg/equiv, in moderately hydromorphic solonchak soils – 12,43-16,31 mg/equiv, in the semi-hydromorphic coastal salt marshes this indicator in the upper soil horizon is 12,28-43,23 mg/equiv. As a result of the studies, the changes occurring in the soil cover under the influence of desertification were studied, and together with these, the features of drought and desertification processes and their influence on the transformation of the soil cover were studied. As a result of climate change, drying up of the sea, lack of water resources, desertification processes in these territories are accelerating, which in turn leads to drying out of soils, including deterioration of the properties and characteristics of irrigated soils and their reclamation state. In particular, lands with a severe reclamation state in the Aral Sea region comprise 162 thousand hectares, the main reason for which is an increase in the degree of salinization of soils. Under the influence of desertification, the total area of the Aral Sea lands subject to salinization is 91,4%. This phenomenon will not make it possible in the future to increase the yield of cultivated crops.
As a result of desertification processes, 84,7% of the old irrigated meadow and alluvial soils of the Ravshan massif of the Kungirat district, 50,5% of the irrigated meadow and alluvial soils of the Saryaltin massif of the Kanlikul district, 56,7- 81,8% of old and newly irrigated meadow and alluvial soils of the massif.Khamza of the Khojeyli region, 69,7% of the old and newly irrigated meadow and alluvial soils of the Kilichboy massif of the Amudarya region, 74,2% of the newly developed and newly irrigated meadow and alluvial soils of the YangierEllikkalinsky district and 81,8% of the newly irrigated meadow and alluvial soils of the Kiyatbad massif of the Beruniy district degradation and degumification processes. In the non-irrigated territories, especially in the modern and former “living” river deltas, as a result of a sharp decrease in the groundwater level, a noticeable change in the vegetation cover and the development of xerophytes were observed. Under these conditions, soil cover development processes occur depending on the lithological and geomorphological conditions of the parent rock. Soil transformation can be represented in the following sequence: marsh → marsh-meadow → meadow takyr (gray-brown, desert-sand, salt marshes) → takyr (takyr, gray-brown, desert-sand) soils. A sharp decrease in groundwater levels, intensive development of desertification processes leads to a violation of the above scheme. Swamp soils pass into marsh-meadow soils without passing into the stage of meadow soils, semi-automorphic and automorphic
Soil cover of the aral sea region and change of soil properties under the influence of desertification (on the example of soils of the karakalpakstan region) 627
soils pass into gray-brown, takyr and desert-sand soils. In the course of its evolution, over a 60-70-year period, fundamental changes have occurred in the development of soils and soil cover of this region, associated with the widespread development and irrigation in the region. As far as we know, irrigation processes greatly alter the soil and soil cover. In the early forties, fifties, primitive takyrserozems or takir soils prevailed here, in places with spots of takyr, sand and salt marshes. The lowest parts were occupied by alluvial-meadow, swamp-meadow and swamp, gravitating to the territory of the former "living" Amu Darya delta. Most of the territory is occupied by automorphic desert soils, especially characteristic of the left bank of the lower reaches of the Amu Darya. According to Kimberg, Kochubei and Shuvalov (1964), several evolutionary genetic transformations took place over several decades of the soil, which were expressed, as a whole, in the begun tearing of natural landscapes. Since the sixties, in connection with the widespread development of irrigated agriculture, the soil and soil cover of the Konlikul region began to change significantly. Tinning processes have intensified, which have now led to the widespread development of hydromorphic meadow, alluvial soils of different irrigation durations. The soils of the irrigation zone of the Konlikul district of Karakalpakstan are located in the northern sub-province of the subtropical desert zone of the modern Amu Darya delta. A characteristic feature of these soils is the complex layering of the lithological structure, composed of layered alluvial deposits, which largely determines the basic properties of the studied soils. In addition, the soils of this region differ in the age of development, cultivation, the degree of salinization and the availability of humus and nutrients. Such soils are widespread in the territory of the region: irrigated takir-meadow, takir- meadow virgin, irrigated meadow, formerly irrigated meadow, virgin meadow and salt marshes. But, despite this, in the late 50-60s, the water flow of the Amu Darya and Syr Darya sharply decreased; this led to significant changes in the natural and ecological situation of the Aral Sea region. With the drainage of the Aral Sea, the process of global desertification and changes in the conditions of soil formation began here. A decisive role in soil-forming processes began to play an arid-zonal factor, which caused a sharp transition of hydromorphic soils to automorphic desert ones. It is such a quick transition, when the level of groundwater has significantly decreased over the course of several years and the desiccation of soils has occurred, predetermined the uniqueness of their evolution at the first stage of aridization. As a result of the development of evolutionary processes, evolutionary soils fell out of the evolutionary chain and the transition from meadow to marsh soils, characteristic of the ancient delta plains of the lower reaches, was erased. The soil genesis at this stage, with the exception of salt marshes, is almost completely determined by the traits inherited from previous, initial soil formation processes. Therefore, the soils of the first stage - the drying stage, which lasts 25-30 years, belong to the residual meadow and residual meadow tugai. And together, with these soils, salt marshes are formed, which also have residual signs of the initial floodplain-alluvial soils. Section 21. The drained bottom of the Aral Sea. Smooth and hilly plain, only occasionally small sand dunes. The tops of the hillocks are crowned with Kandym, Circassia Saxaul. Sandy sedge is rarefied in depressions; occasionally, a withers and a boyal. 0-1
cm. Pale gray, loose, Aeolian, coarse, variegated sand. 2-10 cm. Sand, slightly compacted, weakly layered with a fairly large number of sedge roots; 10-32 cm. The same color, sandy loam with sparse roots, insect passages and weak vertical cracks; 32-50 cm. The same color, sandy loam with rare blurry dirty-white spots of lime, near which a heterogeneous lumpiness is noticeable, rare roots and vertical cracks are found; 50-100 cm. Pale gray, Aeolian sand, without neoplasms, slightly compacted, holds the wall well; 100-135 cm. Sandy, slightly gravelly, yellow-gray, whitish, a lot of carbonate, in the form of dirty white spots; 135-200 cm. Loam coarse sandy, whitish-fawn, starting from 170 cm reddish- yellow, dense gypsum. There is a semi-rolled pebble and lumps of nodule sandstone with gypsum and nodules of loam and clay of brown-red color; 200-280 cm. Coarse sand, up to 240 cm rusty gray, lower gray with the inclusion of small jackdaws, lumps of nodule sandstone with gypsum and nodules of loam and clay of brown-red color. Compacted sand; 280- 400 cm. Dry gypsum clay, lying in separate rounded sections, between which there is coarse sand, a sharply limited layer of fine and medium ash gray cross-bedded sand, strongly cemented by gypsum, includes a lens of large nodules of reddish clay, rare weak rusty spots; 400-480 cm. Wet, dense, ocher-yellow sandstone. The described section represents a desert sandy soil. Starting from the top and to the horizon of 130 cm, the parent soil proper is aeolian sand, which in turn buries tertiary sandstone at a depth of 400 cm. The desert sandy soil represented by this section seems to correspond most of all to the loose-sandy gray soil of A.N. Rozanov.
As a result of global climate change, the disturbance of the natural balance for a long time and, first of all, the redistribution of water reserves, the intensification of the drought of the coastal area under the influence of the drying of the Aral Sea, caused a noticeable change in the soil cover. These changes led to a sharp decrease in groundwater in the territories of the former "living" Amu Darya delta, an increase in their mineralization, a decrease in vegetation cover, a manifestation of the evolutionary process characteristic of the soil cover; as a result of the transition of most of the hydromorphic soils of the territory of the ancient and former “living” Amu Darya delta to automorphic, previously widespread soil subtypes such as meadow-bog, silt-bog, peat-bog, residual-tugai, as a result of a sharp decrease in groundwater, they turned into residual - marshy, residual-solonchak, meadow-takyr, gray-brown or sandy-desert subtypes and soil types; the decrease in the intensity of land irrigation and their agricultural use in the territory was the result of a violation of the ratio between salts and water, Jour of adv research in dynamical & control systems, vol. 12, special issue-06, 2020
628
DOI: 10.5373/JARDCS/V12SP6/SP20201072 *Corresponding Author : Bakhtiyor RamazonovichRamazonov Article History: Received: Mar 24, 2020, Accepted: June 27, 2020 salinization of soils, and a decrease in soil fertility and crop yields. Under the influence of such negative phenomena, the soils of the previously hydromorphic regime, non-irrigated coastal areas, switched to semi-automorphic and automorphic regimes, therefore, intensified salinization, degradation, and dehumification processes are observed in them; Currently, the soils spread in the Republic of Karakalpakstan are saline to varying degrees. In 1995, territories with a difficult reclamation state of irrigated soils of key sites were noted in the Aral Sea regions, then in 2016 they were joined by the Chimbay, Takhtakupyr, Shumanay, Nukus and Khojeyli districts. The reclamation state of the irrigated lands of these areas is complex, land areas are subject to degradation and desertification. The absorption capacity and composition of the absorbed soil cations are important indicators that determine the properties and characteristics of soils, their degree of fertility and productivity. In the absorbing complex of irrigated soils, the largest share of magnesium and sodium is 4,41-46,70% and 5,62-10,74%, and these soils are brackish, salinity type is sulfate-chloride, chloride; medium and severe saline; in gray- brown and takir soils, the amount of magnesium is 23,1-27,1% and sodium 7,5-16,1%; in residual bog soils, respectively 34,75-56,35% and 12,75-13,49%; on very strongly saline and saline soils of the farms of Tulkun, Amudarya district, Sarialtin Kanlikul and named after Yu.Akhunbabaev of the Kungirat region, there is a large number of reserves of readily soluble salts, which in the upper 0-2 meter layer range from 525,0-570,7 tons to 812,1 -973,6 tons, of which 308,7-582,5 tons are in the upper 0-1 meter layer; it was found that 84,7% of newly irrigated meadow and alluvial soils of the Ravshan massif, 50,5% of newly irrigated meadow and alluvial soils of the Saryaltin massif, 56,7-81,8% of old and newly irrigated soils of the Khamza massif are found to be subject to degradation and degumification. It is also noted that in the Muynak region on hydromorphic salt marshes, salts are found on the surface in the form of a crust, and the soils themselves are saline to a very and very strong degree; Based on the results of the analyzes, soil maps and agrochemical cartograms of the supply of soils with nutrients for selected key areas on a scale of 1:10000 were compiled, and based on them, recommendations were given for restoring and improving soil fertility, the rational use of fertilizers, and also the location of crops taking into account soil properties ; the information obtained on the transformation and change in the properties of the soil cover of the territory as a result of climate change and the drying of the Aral Sea will enrich soil science, and can serve as the basis for land monitoring of the republic. With the desiccation of the Aral Sea and desertification of the delta, its biogeocenoses sharply declined and its tugai vegetation dried up. Reed is modified into molding forms and perishes. Most of the territory of the Aral Sea is used as pastures, often unproductive. In the future, with the broad development of the processes of desertification and degradation, the quality of pastures will further decrease. Proceeding from this, it is necessary to resort to periodic flooding of pasture and hayfields, which simultaneously with increasing their productivity somewhat suspend the desertification of individual territories. It should also be noted for a good experience of creating the juniper reeds in Muynak. At the stage of desertification, the soil will acquire the characteristics of one of the zonal soils-takyr, desert sandy or residual solonchaks. Differences in soil processes in the prognostic stage are smoothed out, but facies differences that predetermine salinity, deflation, the degree of profile differentiation to genetic horizons, and fertility indicators of soils acquire great importance. In extra arid conditions, there is a further convergence of soils, and the main indicators on which their division was-the content of humus, the level of provision of gross and mobile forms of nutrients is leveled. The level of facies and lithologic properties or differences in the mechanical composition come to the fore. According to V.Y. Sektimenko and other scientists, based on the study of soil cover, the main variety of soils in the lower part of the Amudarya delta can be represented by the following list: I-hydromorphic: 1-meadow-residual-bog, 2-solonchaks typical, 3-solonchaks bog, 4-solonchak-meadow; II- transitional: 1-residual-bog, (a-drying, b-dried, in-desiccated), 2-residual-meadow (a-drying, b-dried, in-desiccated), 3- residual-meadow tugai (a-drying, bdried, in-desiccated), 4-meadow-takyr, 5- solonchaksresidual-bog, 6-solonchaks- residual-meadow. III-automorphic: 1-takyr, 2-desert sandy (a - on alluvial deposits, b–on tertiary sandstones), 3-solonchaks residual. IV-irrigated: 1-meadow, 2-meadow-takyr. The systematic list reflects both the classificationtaxonomic levels of genetic groups of soils in accordance with the “Classification and diagnostics of soils” (1977), and the same indicators according to the classification of B.V. Gorbunov and N.V. Kimberg [6]. In addition, the list includes classification- taxonomic levels for residual-bog, residual-meadow, residual-meadow tugai soils, as well as solonchaks-residual meadow and residual-marshy [24] which are revealed in the delta for the first time. The aforementioned soils represent one of the stages of drying of bog soils formed in these territories during the past alluvial-flood regime of humidification, which is also reflected in the residual signs of the marsh process along their profile. Therefore, these meadow soils are referred to meadow residual-bog soils, which, with further drying of the delta, can go to meadow-takyr or residualmeadow through a stage of intensive salinization. Meadow residual-bog soils occupy the youngest surfaces in the lower part of the Amu Darya delta and are mainly confined to territories that, as a result of local support of river and waste waters, maintain a close groundwater level, most often within three meters. The profile of soil data is characterized by the presence of gley horizons in both the upper and lower layers. In the absence of flooding, there is an effusion and dissociative-effluent water regimes that, with mineralized groundwater, contribute to the formation of a salt profile in the type of solonchaks. With meadow soil formation, a special composition of vegetation develops. In meadow residual-bog soils, first of all, reeds grow, which, with increasing drying, turns into a creeping shape, in the form of separate plants up to 10–15 cm in height. Meadow communities from tamarisk, reed, and chingil come to replace marsh vegetation. From leguminous plants there is licorice, and also a camel thorn. With increasing of soil salinity, meadow vegetation dies off, giving way to halophytes – Kareliania, parselystnik, Kermek, some solyanka. Meadow residual-bog soils are formed mainly on sediments of the lake facies of
Soil cover of the aral sea region and change of soil properties under the influence of desertification (on the example of soils of the karakalpakstan region) 629
sedimentation. In the desert zone, bog solonchaks are widespread, it is a subtype of solonchaks combining salt accumulation with swamping. These solonchaks are called in various places by blinders, salty mud. An indispensable condition for their development are constantly close, highly mineralized, drainless groundwater, which together with capillary removal of salts to the surface of the soil creates conditions for anaerobiosis in it. This affects the strong gleying of the entire profile. Solonchaks of the described subtype are developed on the coasts of saline lakes, as well as in closed depressions of modern alluvial plains. The profile of the bog solonchaks of the desert zone is given in the example of the sample cut No. 27. Sample cut 27, 2017 August 23. B.R. Ramazonov, A.J. Ismanov [16]. Muynak district, from the road 350 meters to the north-west. The surface is devoid of vegetation and covered with a rough dark crust with white spots. 0–1 cm. Earth-salt, durable moist crust. 1–6 cm. Rick, moist, saturated with salts. 6–40 cm. Light-brownish, gray and rusty patches, weakly dense, wet loam. 40–92 cm. Clay of the same color, but with 75–78 cm intensely blue with bright rusty spots, reed residues and a mass of large particles of gypsum. 92–150 cm. The whitish gray, moist, medium sand with large rusty and bluish spots, there are small seashells–Cardium edula. From 150 cm begins salty groundwater. Bog solonchaks are allocated in a large amount of salt accumulation, usually by the chloride character of salinity and increased carbonate content. Residual saline solonchaks of the desert zone–in which the solonchak process has stopped, salt accumulations are relict in character and with them signs of a transition to some sort of, depending on lithology, automorphic soil: takyr or desert sand.As a result of global climate change, the disturbance of the natural balance for a long time and, first of all, the redistribution of water reserves, the intensification of the drought of the coastal area under the influence of the drying of the Aral Sea, caused a noticeable change in the soil cover. These changes led to a sharp decrease in groundwater in the territories of the former "living" Amu Darya delta, an increase in their mineralization, a decrease in vegetation cover, a manifestation of the evolutionary process characteristic of the soil cover; as a result of the transition of most of the hydromorphic soils of the territory of the ancient and former “living” Amu Darya delta to automorphic, previously widespread soil subtypes such as meadow-bog, silt-bog, peat-bog, residual-tugai, as a result of a sharp decrease in groundwater, they turned into residual - marshy, residual-solonchak, meadow-takyr, gray-brown or sandy-desert subtypes and soil types; the decrease in the intensity of land irrigation and their agricultural use in the territory was the result of a violation of the ratio between salts and water, salinization of soils, and a decrease in soil fertility and crop yields. Under the influence of such negative phenomena, the soils of the previously hydromorphic regime, non-irrigated coastal areas, switched to semi-automorphic and automorphic regimes, therefore, intensified salinization, degradation, and dehumification processes are observed in them; Currently, the soils spread in the Republic of Karakalpakstan are saline to varying degrees. In 1995, territories with a difficult reclamation state of irrigated soils of key sites were noted in the Aral Sea regions, then in 2016 they were joined by the Chimbay, Takhtakupyr, Shumanay, Nukus and Khojeyli districts. The reclamation state of the irrigated lands of these areas is complex, land areas are subject to degradation and desertification; The absorption capacity and composition of the absorbed soil cations are important indicators that determine the properties and characteristics of soils, their degree of fertility and productivity. In the absorbing complex of irrigated soils, the largest share of magnesium and sodium is 40,41-46,70% and 5,62-10,74%, and these soils are brackish, salinity type is sulfate-chloride, chloride; medium and severe saline; in gray- brown and takir soils, the amount of magnesium is 23,1-27,1% and sodium 7,5-16,1%; in residual bog soils, respectively 34,75-56,35% and 12,75-13,49%; on very strongly saline and saline soils of the farms of Tulkun, Amudarya district, Sarialtin, Kanlikul and named after Yu.Akhunbabaev of the Kungirat region, there is a large number of reserves of readily soluble salts, which in the upper 0-2 meter layer range from 525,0-570,7 tons to 812,1 -973,6 tons, of which 308,7-582,5 tons are in the upper 0-1 meter layer; it was found that 84,7% of newly irrigated meadow and alluvial soils of the Ravshan massif, 50,5% of newly irrigated meadow and alluvial soils of the Saryaltin massif, 56,7-81,8% of old and newly irrigated soils of the Khamza massif are found to be subject to degradation and degumification. It is also noted that in the Muynak region on hydromorphic salt marshes, salts are found on the surface in the form of a crust, and the soils themselves are saline to a very and very strong degree; Based on the results of the analyzes, soil maps and agrochemical cartograms of the supply of soils with nutrients for selected key areas on a scale of 1: 10,000 were compiled, and based on them, recommendations were given for restoring and improving International Journal of Psychosocial Rehabilitation, Vol. 24, Issue 04, 2020 ISSN: 1475-7192 Received: 22 Sep 2019 | Revised: 13 Oct 2019 | Accepted: 15 Jan 2020 4145 soil fertility, the rational use of fertilizers, and also the location of crops taking into account soil properties ; the information obtained on the transformation and change in the properties of the soil cover of the territory as a result of climate change and the drying of the Aral Sea will enrich soil science, and can serve as the basis for land monitoring of the republic [19]. The study of the quantitative distribution of microorganisms in the studied soils showed the dependence of the number of different physiological groups within the same soil type on the content of organic matter (humus), the degree of salinity, and the type of vegetation. Changes in soil conditions significantly affect the generic and species composition of microorganisms, but do not affect the presence of a particular physiological group. The total number of ammonifiers - bacteria, fungi, actinomycetes in soils -the arable layer is relatively low 80-312 thousand/ha. The largest number of ammonifiers is found in slightly and medium saline soils and in soils with a high content of humus. Such specificity is also observed in the increase in the number in the soils of spore bacteria. However, their number was several times less than 10- 31 thousand/g than ammonifiers. In the species composition of spore bacteria on weakly and medium saline soils,
Jour of adv research in dynamical & control systems, vol. 12, special issue-06, 2020
630
DOI: 10.5373/JARDCS/V12SP6/SP20201072 *Corresponding Author : Bakhtiyor RamazonovichRamazonov Article History: Received: Mar 24, 2020, Accepted: June 27, 2020 megaterium, Bac subtilius prevail on highly saline Bac mycoides, Bac cereus, and Bac Virgulis. In cultivated soils, the relative content of Bac megaterium, Bac idosus and Bac mycoides increases in large quantities in soils rich in organic matter, and with an increase in its content, the growth of these bacteria increases. Oligonitrophilic microorganisms are widespread in the studied soils[20]. Evolution of soils of the Aral Sea area under the influence of anthropogenic desertification. The ability of oligonitrophils to develop at a very low nitrogen level in the substrate provides the possibility of their development under adverse conditions for other microorganisms. Oligonitrophils are involved in the completion of mineralization processes and have nitrogen-fixing ability. Oligonitrophilic microorganisms develop better on weakly and moderately saline soils. Free-flowing nitrogen-fixing bacteria (azotobacter) were not found on saline’s (virgin lands) and in soils under a rice field, and in other soils their number was in the range of 10-80 thousand/g. the soil. Higher numbers of azotobacter occur in slightly saline soils, and low in highly saline soils. Denitrifying bacteria are present in all soils and their content is relatively small and close to 70-110 thousand/g. The number of fungi compared with other microorganisms is low. 8-20 thousand/g. A higher content of mushrooms is observed in soils under cotton, alfalfa and corn. In slightly saline soils, Aspergillus, Penisillum are richly represented, and Mucor Micoida, Trichoderma lignorum are widespread in smaller quantities. The species composition of the Penisillum genus is especially widespread and diverse. Actinomycetes have an extensive distribution area and make up an important part of the soil microflora of the study area. The number of actinomycetes is significantly higher in soils under cotton, wheat, corn, alfalfa and reaches up to the limit of 2000-2500 thousand/g than under rice 213 thousand/g. Under cotton and wheat, a predominance of actinomycetes from the section Cinerus, Roseus was revealed. The high content of actinomycetes in the microbial associations indicates that the mineralization of organic matter is intensive in these soils. Actinomycetes isolated from soils under cotton and alfalfa has high antibiotic activity. In medium and slightly saline soils, gray and brown-brown actinomycetes are widespread. In slightly saline soils, the number of actinomycetes with white aerial mycelium is insignificant. A study of the antagonistic properties of selected actinomycetes with respect to the main pathogens of cotton diseases – Dahliae, X.malvaceurum, R.Solari showed that the greatest number of antagonists was detected in soils under alfalfa 27–33%, under cotton 23–30% and corn 23–27%, slightly less under wheat 16-21% and in virgin soils 8-15%. The smallest number of antagonists is noted in the soil under rice. Among the selected actinomycetes, 12% were antagonists. Also, nematodes, footstails, soil mites and earthworms are common in these soils. Nematodes eat various food-bacteria, mycelium of fungi, plant debris, and some suck the contents of soil mite eggs, many feeds on soil unicellular algae. In the soils of the study area, especially in the newly developed number of nematodes, which indicates a wide variety of them. These nematodes belong to Chromoderida, Enoplida, Rhabditida, Tilenehida. In cotton agrocenoses, the gross composition and the number of nematodes is sharply reduced. Here mainly zoophagous that are not involved in the decomposition of plant debris are found. Nematodes dominate in slightly saline soils [ 3]. Download 422.53 Kb. Do'stlaringiz bilan baham: |
ma'muriyatiga murojaat qiling