Journal of critical reviews
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- Review Article MORPHOGENETIC CHARACTERISTICS AND BIOLOGICAL ACTIVITY OF TAKYR AND
- ACTIVITY OF TAKYR AND MEADOW SOILS OF THE REPUBLIC OF KARAKALPAKSTAN (ON THE EXAMPLE OF SOILS OF CHIMBAY DISTRICT) Ramazonov B.R.
- Accepted: 12.03.2020
- INTRODUCTION
Journal of critical reviews 243
Journal of Critical Reviews ISSN- 2394-5125 Vol 7, Issue 5, 2020
1 Tashkent Regional Chirchik State Pedagogical Institute, Tashkent, Uzbekistan. : b.ramazonov@cspi.uz Received: 14.01.2020 Revised: 11.02.2020 Accepted: 12.03.2020 Abstract This article is devoted to the problems of desertification, the problems of desertification is one of the most striking examples of complex soil degradation, which includes such unfavorable processes as erosion, deflation, salinization, salinization, re-compaction, and others. And also, the article deals with such common soils as: takyr, meadow-alluvial, salt marshes, residual-bog, takyr in combination with residual salt marshes, takyr in combination with desert sandy soils and sands, takyr-meadow, takyrno Meadow in a complex with desert meadow, meadow, bog meadow soils. In addition to the above, we are also talking about the vegetation cover, which is represented by hodgepodge, tamarix, and sometimes on saxaul on adjoined soils. 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, and a manifestation of the evolutionary process characteristic of the soil cover. These and other signs of soil and soil cover of these territories are highlighted. Keywords: Aral Sea, Amu Darya delta, mineralization, soil cover, types and degrees of salinization, absorption capacity, cations, salinization, physical clay, hydromorphic and automorphic soils, turf horizon, humus formation, fertility, land reclamation state. © 2019 by Advance Scientific Research. This is an open-access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) DOI:
http://dx.doi.org/10.31838/jcr.07.05.43
INTRODUCTION Problems of desertification are one of the most striking examples of complex soil degradation, which includes such adverse processes as erosion, deflation and salinization. Salt formation, compaction and others. The UN Convention to Combat Desertification defines desertification as “land degradation in arid, sub arid and arid sub- humid areas as a result of various factors, including climate change and human activities” (Paris Convention, 1994). Over the past decades, the need to increase the need to increase agricultural production in Central Asia in order to feed the growing population of the region has exerted increasing pressure on soil and water resources. An increased seeding coefficient and low moisture availability for plants is one of the typical soil properties in arid regions of Central Asia. Common soils in the study area are strongly altered under the influence of desertification processes, their mechanical composition, agrochemical properties, as well as changes in soils and soil cover under the influence of degradation and desertification processes. MATERIALS AND METHODS Soils such as takyr, meadow-alluvial, salt marshes, soil complexes, residual-bog, takyr in combination with residual salines, takyr in combination with desert sandy soils and sands, takyr-meadow, takyr-meadow in the Chimbay region are widespread: with desert meadow, meadow, bog meadow soils. The above mentioned soils of the Chimbay region are divided into old irrigated, newly irrigated, newly developed, conditionally irrigated, fallow and virgin. Takyr soils formed in the northern part of the region are april- covered residual-meadow and residual-bog soils that survived the stages of drying and desertification. Their modern development takes place exclusively under the influence of arid-zonal climatic factors, such as with the drying out of groundwater and the removal of the Aral Sea. The vegetation cover is sparse and is represented mainly by hodgepodge, tamarix and sometimes on saxed soils on saxaul. The morphological profile of virgin, takyr soils is characterized by the presence of a surface soil crust more or less dense, porous and fractured. When moistened, the crust melts, and becomes very poorly permeable. Under the crust lies a loose or slightly densified scaly-powdery horizon. The middle part of the profile is densified and brownish in color, with a heavy mechanical composition - lumpy - lumpy structure. In general, the described takir soils are characterized by a weak morphological formation, which is explained by their relative youth, which is also confirmed by the presence in the profile of clear signs of past hydromorphism. In some places, takir soils, regardless of their mechanical composition, are secured from the surface, which is explained by the presence of foci of deflation nearby. The humus content of these soils is different and often in the upper horizons reaches comparatively high values of 0,8-1,3%. The amount of gross nitrogen, depending on the humus content, ranges from 0,06-0,1%. The C: N ratio varies from 8 to 14, which indicates a relatively weak enrichment of humus with nitrogen. Soil carbonate, depending on the mechanical composition of the layers, ranges from 8.7 to 13,7%. The composition of carbonates is dominated by calcites. Gypsum in the soil is very small 0,1-0,4%. Ph is slightly alkaline and alkaline. The amount of absorbed bases, even in heavy mechanical composition and humus horizons, does
MORPHOGENETIC CHARACTERISTICS AND BIOLOGICAL ACTIVITY OF TAKYR AND MEADOW SOILS OF THE REPUBLIC OF KARAKALPAKSTAN (ON THE EXAMPLE OF SOILS OF CHIMBAY DISTRICT)MORPHOGENETIC CHARACTERISTICS AND BIOLOGICAL ACTIVITY OF TAKYR AND MEADOW SOILS OF THE REPUBLIC OF KARAKALPAKSTAN (ON THE EXAMPLE OF SOILS OF CHIMBAY DISTRICT)
Journal of critical reviews 244
not exceed 10-12 mg/equiv. All takyr soils are very, very strongly salines soils. Takir-meadow soils, as well as takirs, are formed in the northern part of the region. These soils are mainly located on the periphery of the irrigation zone, the influence of which caused the rise of groundwater in this territory and the evolution of takyr soils into takyr-meadow soils. According to the development conditions, takyr soils occupy an intermediate position between automorphic (takyr) and hydromorphic (meadow) soils. They develop in conditions of weakened soil moisture. In the territory of the region, groundwater lies at a depth of 2,5-4 m and creates a semi- hydromorphic regime of moistening of soil. Takyr soils that survived the hydromorphic stage in their evolutionary development and retained some of its residual morphological features now quickly acquire the properties of hydromorphic soils. Takyr-meadow soils, being transitional, combine the features of takyr and meadow soils. In the middle and lower parts of the profile, oxidation-reduction processes are activated, ocher-rust and bluish spots appear or renew, and on the surface of virgin soils, a crust with a characteristic fracture and a sub crustal horizon are still preserved. In the irrigated takyr meadow soils, the arable horizon up with a thickness of 25-30 cm is distinguished, this layer of gray or dark gray light, sometimes with a brownish tint. According to the mechanical composition of soils, different - from clay to sandy loam. Depending on the granulometric composition, the soil structure is lumpy-clumpy or lumpy-dusty. The routines of the arable horizon is usually weak; there are remains of fragrant vegetation. Below the arable horizon, layers are slightly altered by irrigation. Their humidity is slightly higher than virgin and more radicular. The lithological structure of the profile is distinguished by sharp and random layering. With heavy mechanical composition, the profile is always dense. With strong salinization of soil along the profile, especially in the zone of dispersal of capillary moisture, the accumulation of salts is morphologically expressed by white spots. Meadow alluvial soils are widespread in this region. Here to occur with the active influence of groundwater on soil formation processes. The depth of groundwater is 1-2,5 m. Their irrigation- alluvial regime with an amplitude of fluctuation of the level of 0,5- 1,0 m. The highest level location is observed during washing and vegetation irrigation. The high standing of groundwater causes waterlogging of the lower part of the profile, which leads to the development of redox processes, and as a result rusty, brown and brownish-black gleying spots form in the profile. Irrigated- meadow soils are the most common soils among the irrigated lands of the region. In addition to the existing hydrogeological conditions, their formation is greatly influenced by irrigation, which largely suppresses the role of arid-zonal factors in soil formation processes; therefore, meadow alluvial soils belong to the group of azonal soils. The morphological profile of irrigated soils is characterized by the presence of an arable horizon Ap with a thickness of 25-32 cm. It has a gray or light gray color, dry or wet, depending on the mechanical composition - lumpy-clumpy or lumpy-dusty structure, plant debris is often found. The mechanical composition - from clay and heavy loam to sandy loam and sand. The humus- accumulative horizon in old-irrigated meadow soils reaches a thickness of 50-60 cm. In newly irrigated soils, it is limited and only occasionally go beyond the arable horizon. It has a gray color, in places with a brownish tint, radicular. Depending on the granulometric composition of soils and the content of organic matter, it can be structured or structureless. Water-soluble salts often accumulate in the arable layer. Salt marshes are distributed mainly in the northern part of the region, characteristic of all salt marshes is a high accumulation of salts in the upper horizon, which personifies the essence of the salt marsh. In this horizon, salts are usually >3%. Along with salt marshes, virgin soils are very widespread in the region. Not having morphological traits of salt marshes, but containing salts in the upper horizon >3%. Salt marshes have a swimming surface - the appearance of soiled soil, sometimes with salt fading and plant litter. Old soils, but not irrigated lands, are often represented by such soils. Among salt marshes, residual and typical are distinguished. Residual salines are mainly formed near takir soils, where a relatively deep groundwater table of 3-5 meters or more, with a sharply layered profile of soil in terms of mechanical composition, helps to weaken or break the capillary connection of mineralized groundwater to surface horizons. In such conditions, the development of the saline process either weakens or is excluded. Such salt marshes are residual and represent modern automorphic and semi-automorphic soils. The amount of salts in them practically does not change over time, only some of their seasonal migration along the profile occurs. Among the residual salt marshes, puffy, cortical-puffy and cortical are distinguished. In the upper horizon, the maximum amount of salts is concentrated, reaching 12% or more. According to the mechanical composition, the profile of soils varies from loam to sandy loam. The amount of humus in the upper horizons of these salt marshes, depending on the mechanical composition, ranges from 0,5-0,7 to 1,0-1,7%. Down the profile, its content decreases to 0,3-0,7%. Humus is poorly enriched with nitrogen, as indicated by the wide ratio of carbon to nitrogen. The nitrogen content is low, reaching up to 0,1%. Soil carbonate in the profile of 6,0-10,7%. Calcites predominate in the composition of carbonates; in very highly saline soils, the proportion of magnesium increases. Gypsum in the profile is small up to 1%, only in the upper saline horizons its content sometimes reaches 4-7%. Residual salt marshes constitute a significant share of the reserve lands. Difficulties in the development of these lands are the need for large amounts of reclamation work. More than 2% of the district’s land is unsuitable for irrigation, but can be used as pasture. These include complexes of salt marshes with desert sandy soils and sands and sand massifs. The increase in the area of irrigated lands in the last 40-50 years was mainly due to the development of virgin-fallow meadow soils, as well as takyr and takir-meadow and saline residual, which evolved into meadow soils some time later. Now irrigated meadow soils in the region occupy about 45-50% of the area, and takyrno- meadow soils about 2-5%. Soil complexes are distinguished in cases when various soils develop in close contact and, due to their fine contouring, cannot be isolated separately at a given potato base scale. Their formation is primarily determined by the relief. Complexes of takyr soils with fine-clumpy sands and desert sandy soils developed from them were formed as a result of the partial destruction of the alluvial-delta plain by the wind, redeposition of sand and the formation of complex erosion-accumulative landforms. This happened during the global drying of the delta. Deserted sandy soils are formed on the sandy substrate of tuberous formations, overgrown with saxaul, dzhuzgun and sand sediment, and takyr in loamy surfaces. Takir soils are sandy, are at the formation stage. The mechanical composition of takyr soils is light loam and sandy loam. As a result of the general rise in groundwater caused by the expansion of irrigated land and increased water discharge, along the northern periphery of the oasis, takyr soils, including those included in complexes, evolved not only in takyr-meadow, but in certain conditions, salt marshes. Thus, takyrno-sandy complexes were transformed into saliney- sandy, they are formed among takyrn-meadow soils. Groundwater under salt marshes lies at a depth of about 2.5 m, and under sand formations - below 4 m.
MORPHOGENETIC CHARACTERISTICS AND BIOLOGICAL ACTIVITY OF TAKYR AND MEADOW SOILS OF THE REPUBLIC OF KARAKALPAKSTAN (ON THE EXAMPLE OF SOILS OF CHIMBAY DISTRICT)MORPHOGENETIC CHARACTERISTICS AND BIOLOGICAL ACTIVITY OF TAKYR AND MEADOW SOILS OF THE REPUBLIC OF KARAKALPAKSTAN (ON THE EXAMPLE OF SOILS OF CHIMBAY DISTRICT)
Journal of critical reviews 245
The lithological profile of soils in saline-sand complexes is represented by sandy loams and alluvial sands redeposited by the wind. As a result of saline soil formation, sandy loamy soils in depressions acquired a saline crust saturated with salts. Their profile is also very salted. In the lower part of it there are rusty and bluish spots of gleying. Salt marshes and rarely tamarisks grow on salt marshes. On the elevated elements of the relief, the sand sediment fragmentarily forms a loose turf (Hell) with a thickness of 18-22 cm, which is covered from above with loose sand (1,5-2 cm). Under it, in horizon B, in places there is a slight compaction and high radicularity, which speaks of the appearance of signs of desert soil formation. Humus in horizons A and B of sandy soils 0,3-0,6%, nitrogen 0,03-0,09%, carbonates 6-7%, soil reaction alkaline pH = 7,8-8,0. Takyr-meadow and takyr soils are the main suitable reserve irrigation land fund. After the application of high agricultural technology, these soils are quickly cultivated and provide high crop yields. The exception is a complex of takyr soils with desert sandy soils and sands. The transformation of hydrogeological conditions in a significant part of the region towards an increase in groundwater levels and increased soil moisture profile due to increased water supply and widespread irrigation of virgin-fallow lands, on the one hand, and territorial changes in the area, as well as lowering the capacity of collector-drainage networks, have led to over the years, to significant changes in quantitative and qualitative indicators of land and soil resources of the Chimbay district. Takyr residual-bog soils - the possibility of a drastic change in the regime of soil moisture in alluvial regions, especially delta regions, determines various patterns of soil cover evolution. If, during the smooth drying of the alluvial region, fresh various river deposits in the presence of a marsh stage will necessarily pass through the meadow, and then desertification will occur, then due to hydrological “cataclysms” in the form of rapid siltation of the initial head of the duct feeding the flood basin, one of the hydromorphic stages of soil development the cover may fall and, for example, bog soils, bypassing the meadow stage, may undergo desertification. Thus, bog soils can occupy a similar meadow place in the evolutionary series: fresh river sediments - bog floodplain- alluvial soils-bog alluvial soils - bog-takir soils - takir soils. On the northern and eastern outskirts of the Amu Darya delta, peculiar surfaces formed that struck by a combination of seemingly contradictory natural elements: takyr peel and reeds or takyr peel and peat-like plant mass. The dry stalks of reeds, forming a similarity of hummocks on the smooth surface of takyr soils, and the dark spots of peat-like weakly decomposed plant residues, clearly visible on the light gray-gray background of the takyr surface, indicate that wet conditions existed earlier, there was a swamp, reed grew, peat was formed and that the change of these wet conditions to dry occurred very sharply. The presence of the reeds and peat residues in the surface horizon of takyr soils allows us to conclude that a link, meadow soils, takyr soils developed from marsh soils from a chain of successive soils of similar sites.
The study of the irrigated soils of the Aral Sea region, the study of their agrochemical, physico-chemical, biological and other properties, land reclamation, soil evolution, their humus state, soil quality assessment, conservation, restoration and improvement of their fertility were carried out by many domestic and foreign scientists. Such as V.V.Bartold, N.G.Stoletov, N.A.Dimo, B.B.Polynov, B.V.Fedorov, L.T.Tursunov, V.G.Popov, A.Z.Genusov, N.V.Kimberg, R.K.Kuziev, I.T.Turapov, M.M.Tashkuziev, S.Abdullaev, R.Kurvantaev, V.E.Sektimenko, N.Yu.Abdurakhmonov, A.Zh.Ismonov, A.U.Akhmedov, H.K.Namozov, L.L.Suishov, G.V.Stulina, K.Yansgiya, F.A.Shinner, R.Niederbacher, R.Barta, M.Seto etc. However, information about The changes that have occurred in the soil cover of the Aral Sea region, under the influence of desertification, are currently insufficient. Scientific studies to determine changes in soil properties due to drought and desertification processes resulting from global climate change and the drying up of the sea, as well as to prevent or mitigate the negative processes occurring in the soil cover, have not been carried out adequately. The main goal of our research is to establish the transformation of the soil cover of the Aral Sea region under conditions of global climate change, to determine changes in the properties and characteristics of common soils, as well as to develop a set of measures aimed at eliminating the negative processes occurring in them.
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