AGROCHEMICAL PROPERTIES OF SOILS DISTRIBUTED IN THE DRY AREAS OF THE ARAL SEA

ABSTRACT

In this research, the amount of the main nutrient elements in the soil - nitrogen, phosphorus, potassium, and organic matter was analyzed and their importance for agriculture was evaluated. The impact of salinization and desertification processes on soil fertility and agro-ecological problems in the region are analyzed. Also, agrochemical measures aimed at reducing soil degradation and increasing productivity were proposed. The results of this research are important for the development of strategies for solving environmental problems and efficient use of land resources in the Aral Bay region, and are useful for agronomists, ecologists and political scientists.

АННОТАЦИЯ

В работе проанализировано количество основных питательных элементов в почве - азота, фосфора, калия и органических веществ и оценено их значение для сельского хозяйства. Анализируется влияние процессов засоления и опустынивания на плодородие почв и агроэкологические проблемы региона. Также были предложены агрохимические мероприятия, направленные на снижение деградации почв и повышение урожайности. Результаты данного исследования важны для разработки стратегий решения экологических проблем и эффективного использования земельных ресурсов в регионе Аральского залива, полезны агрономам, экологам и политологам.

Keywords: Residual swamps, humus, nitrogen, phosphorus, agrochemicals, state of supply, Aral Sea.

Ключевые слова: Остаточные болота, гумус, азот, фосфор, агрохимикаты, обеспеченность, Аральское море.

INTRODUCION

One of the most pressing problems today is the Aral Sea tragedy, which has a negative impact on humanity, soil cover, plant life, climate, and all living organisms. As a result of the sharp drying of the Aral Sea since 1960, various problems have arisen in the ecological, reclamation, agrochemical properties of soils, and erosion processes. As a result of the negative impact of anthropogenic factors, soil degradation has occurred and has caused severe damage to the ecosystem. It is of great importance to determine the properties of soils formed on the dried-up bottom of the Aral Sea, to prevent and mitigate degradation processes [1], to analyze changes taking place in the Aral Sea region, and to ensure the effective and rational use of land resources. 2.6 billion people in more than 100 countries suffer from the effects of soil degradation and desertification. This affects more than 33 percent of the Earth's surface. Therefore, improving the genetic and agrochemical properties of automorphic and hydromorphic soils forming on the dried-up bottom of the Aral Sea is an urgent task.

Research location and methods. The object of research was the western part of the dried-up Aral Sea bed. Residual wetland soils were selected and soil sections were laid out in the field, morphogenetic characteristics were recorded on field sheets, and soil samples for chemical analysis were taken from genetic layers.

In the process of identifying and performing soils, genetic-geographic, profile-geochemical, field-stationary, chemical and analytical methods were used [1]. Soil chemical analysis was carried out according to generally accepted methods developed at the Institute of Soil Science and Agrochemical Research and based on the manuals on soil chemical analysis by Ye.V. Arinushkina [2].

Residual wetlands - formed in the modern floodplains of the Amu Darya (living delta) and in the dried-up bottom of the Aral Sea, in areas periodically covered with water (lakes) of lowlands and shallow water-filled basins, and in later centuries, as a result of the aridification of the climate, they became a relict and are no longer found in large areas. The relief structure of the dried-up bottom of the Aral Sea has a unique appearance, and in addition to the former delta of the Amu Darya, it is noticeable in the form of a "new delta", that is, as if continuing the former "living" delta of the Amu Darya [3].

Result and discussion

Residual wetlands - formed in the modern floodplains of the Amu Darya (living delta) and in the dried-up bottom of the Aral Sea, in areas periodically covered with water (lakes) of lowlands and shallow water basins, and in later centuries, as a result of the aridification of the climate, they became a relict and did not occur in large areas. The relief structure of the dried-up bottom of the Aral Sea has a unique appearance, and in addition to the former delta of the Amu Darya, it is noticeable in the form of a "new delta", that is, in the form of a continuation of the former "living" delta of the Amu Darya [4].

Since the surface of residual wetland soils is permanently covered with vegetation, they are considered rich in humus, that is, they constantly fall down plant residues and their mineralization and decomposition are accelerated in humid conditions, providing the soils with humus on average [5].

Therefore, it was observed that the humus content in the upper layers of residual wetlands fluctuates on average in the range of 0.700-1.120%. Total nitrogen fluctuates around 0.009-0.090 percent, phosphorus 0.167-0.307 percent, and total potassium 0.474-1.440 percent. Of the mobile forms of nutrients, phosphorus is 2.8-32.7 mg/kg, and potassium is 48-513 mg/kg. The ratio of carbon to nitrogen in residual wetlands ranges from 6.2 to 9.9. Changes in the processes of humus formation have occurred in these studied soils, That is, due to the long dry climatic conditions prevailing in these areas, it was noted that humus is slowly forming in the upper layers of the soil. However, despite this, these soils are still deficient in humus. When analyzing residual wetland soils, nutrient elements fluctuate differently in the layers, the main reason for this is related to the amount of nutrient elements discharged by the Amudarya and Syrdarya waters during the rainy seasons (Table 1, Figures 1-2).

Table 1.

Amount of humus and nutrients in residual wetland soils, in % and mg/kg

The high supply of humus in soils means that the soil is fertile, as it contains sufficient nutrients that can be absorbed by plants. A good supply of humus in soils improves plant growth and development, and increases soil fertility.

Residual marshes and residual meadows formed on the soil-soil covers of the dried-up bottom of the Aral Sea, formed in the lake basins of the sea coast and in the impermeable basins of the land.

After the Aral Sea dried up, a huge mass of plant residues accumulated both above and below the ground, which led to a radical change in the soil-soil cover of the lower reaches of the Amu Darya. Due to the intensification of the salinization process, the area of ​​salt marshes increased sharply to 500 thousand hectares, and by the mid-1950s it amounted to 85 thousand hectares. This includes residual swamp, residual grassland, and residual grassland-bush soils [6, 7, 8].

Figure 1. Exchangeable potassium supply of residual wetland soils

Chemical analysis of mobile phosphorus in the soils of the dried-up Aral Sea bottom using the Machigin method in laboratory conditions. Mobile phosphorus was studied in soil samples formed in 3 periods [9, 10].

Figure 2. Quantitative indicators of exchangeable phosphorus content of residual wetland soils, in mg/kg

As a result of the negative impact of anthropogenic factors, soil degradation has occurred and caused severe damage to the ecosystem. In recent years, the drying up of the Aral Sea has led to the disappearance of large parts of hydromorphic soils, automorphic soils. When studying the morphogenetic characteristics of soils developing at an earlier stage in the areas where these soils were formed, it was found that the soil profile retained signs of previous hydromorphism, such as rust spots, signs of bluish waterlogging, erosion of clay particles to the lower parts of the soil, and erosion of gypsum and carbonates [11]. Periodic studies of soil cover show that the quality of soils has improved in recent years in all regions of the Aral Sea. The intensification of these processes is associated with soil salinization, increased groundwater levels, wind erosion, and the development of desertification, which together lead to soil degradation. As a result of the onset of desertification and degradation processes in the region, the process of soil formation has changed in many soil groups. For example, previously widespread swamp-meadow, moor-swamp, peat-swamp, remnant-grove, swamp and other soil groups are now experiencing intensive processes of automorphic and semi-automorphic soil development [12, 13].

Conclusion

The relict wetland soils studied on the dried-up bottom of the Aral Sea have a diverse agrochemical composition, are characterized by the layering of the soil profile and its unique structural structures. This process is evidence of the uniform introduction of various nutrients and colloidal particles from the Amudarya and Syrdarya rivers over the centuries.

References:

1. Agrochemical methods for studying soils and plants.  OzPITI. Tashkent, 2007. 14-18 pp.
2. E.V. Arinushkina. Guide to chemical analysis of soils. Moscow. 1977. –p. 277-310.
3. A.J.Ismonov., N.Kalandarov, U.Mamazhanova, G.N.Kattaeva, A.T.Dusaliev. Protection and rational use of soils in the Aral water area // Regional Department of the Academy of Sciences of the Republic of Uzbekistan. Khorezm Mamun Academy. Bulletin of the Khorezm Mamun Academy. No. 6/1. 2022. 12-15 pages. Khiva. - http://mamun.uz/uz/page/56.
4. K.Idrisov, A.Ismonov, S.Pirmonova, O.Mamajonova Determination of mobile phosphorus in the soils of the dried-up bottom of the Aral Sea // Journal of Science and Education in Karakalpakstan. (27) - Nukus, - No. 3/2. – P. 7-10.
5. M.E. Saidova Modern approaches to diagnosing the ecological and biological state of irrigated meadow alluvial soils of the Aral Sea region // Abstract of doctoral dissertation. – Tashkent, 2019. – P. 7-20.
6. G.N.Kattayeva, A.J.Ismonov, O.Kh.Mamazhanova, A.T. Dosaliyev Indicators of phosphorus and potassium supply of soils of the dried-up bottom of the Aral Sea // Scientific Journal of Soil Science and Agrochemistry, -Tashkent, 2022. - No. 4. – P. 26-29.
7. T.K.Tomina, A.S.Khaibullin, N.Zh.Azhikina Current state of the soil cover of the dried bottom of the Aral Sea in the eastern part of the Kazakhstan Aral Sea // Soil Science and Agrochemistry. – 2008. – No. 1. – P. 118 126.
8. A.J.Ismonov, O‘.Mamajanova, G.Kattayeva, Raxmonov Z. The role of fluvial sediments in the formation of the Аral sea dried bottom soils. International Science and Innovation journal, in volume 3, issue 6 of International Science journal. Pp.36-41.  2023. ID: 7475/А3.
9. Ismonov A.J., Dusaliyev A.T, Mamajanova U.X. Оrigin, geology, lithology and relief of the Аral sea. ACADEMICIA: an International Multidisciplinary Research Journal. Vol.13, Issue 3, March 2023. рр-22-27, https://saarj.com
10. G. Kattaeva, A. Ismonov. Salt marshes formed on the dried bottom of the Aral Sea // Journal of Scientific Review. (biological sciences). Moscow. 2022, No. 4, pp. 112-117.
11. А.J.Ismonov, А.T.Dusaliyev, N.N.Kalandarov, U.Х.Mamajanova, G.N.Kattayeva //Рrofile of desert sandy soils formed in the Аral sea dried-up seabed // E3S Web Conf. Volume 486, pp.1-5. 2024. 07. 02. IX International Conference on Advanced Agrotechnologys, Environmental Engineering and Sustainable Development (AGRITECH-IX 2023) https: //doi.org/10.105/e3sconf/202448604010
12. R.K.Qo‘ziyev, L.A.G‘afurova, T.A.Abdraxmonov Land Resources and Food Security Central Asia and the Kavkaz. ECFS/ FAO Rim, 2016. – S. 75-129.