The published works of the Aral Caspian Sea comprehensive investigation team are devoted to analyzing the soil improvement conditions of the lower reaches of the Amu Darya River, one of the oldest irrigation oases in Central Asia, which is the ancient cradle of Central Asian culture. The vast plains of the region are currently only partially used for irrigation. It is entirely possible to double or triple the existing irrigation area, so as to revive the largest irrigation area in ancient khwarazmo, which was damaged by the invasion of Genghis Khan. For many years, research has been carried out in this area to develop a detailed irrigation scheme. The author of this book, together with VA akovda, a communication academician of the Soviet Academy of Sciences, has led the activities of the Aral Caspian Sea comprehensive investigation team for many years, including the study of soil improvement in the lower reaches of the Amu Darya River. The main problem raised by the author is to analyze the law of salt mass migration in soil, soil layer and groundwater in the ancient delta of Amu Darya River under the influence of natural process and long-term irrigation. In this field, the Soviet Union's soil improvement science revealed many very important and profound processes, which explained the causes of secondary salinization of newly irrigated and formerly fertile land, and formulated the main ways to eliminate these phenomena. However, the migration process of salt quality in the irrigated oasis depends on so many factors that for each new irrigation object, it is necessary to study the characteristics of the local natural environment, and on this basis, select the most favorable and reliable design scheme for regulating the water and salt status of the irrigated land. We have to do the same when we formulate a plan to eliminate the salinization and swamping of the existing irrigated oasis soil. In the lower reaches of the Amu Darya River, the migration law of salt quality is extremely complicated due to a series of factors, such as the vast area of the ancient Delta, the different formation times of the Delta, the strong cutting of the dried ancient river bed, the significant soil layer bedding, the different times of irrigation culture and irrigation system, the repeated diversion of the main river channel of the Amu Darya River, and the recurrence of flood conditions on the formed Delta. Therefore, it is of great significance for the irrigation practice in the lower reaches of Amu Darya River to find out the general law of water and salt mass transfer under these conditions. The analysis of the general law of salt migration with groundwater and its interaction with soil and soil layer is based on the position that the main source of salt accumulated in modern and ancient deltas is the fresh water of Amu Darya River itself. In this regard, the book develops the author's view on the river origin of soil and water salinity in the Volga River Delta, as well as the views of F. n. Kunin and va. a. kovda. They regard the salinization of groundwater, soil and soil layers, especially in the Karakum Desert, as the result of the salt carried by Amu Darya River and other rivers. Some of the arguments set forth in the book, such as the possibility that salt in dry saline soil may rise from deep groundwater through membrane capillary action, are of a discussive nature; For a series of problems, especially the capillary movement of water in layered soil, only preliminary exploration materials have been obtained. The author hopes that the publication of this book will lead to the discussion of controversial issues, promote the further study of the problem of insufficient research, and help to solve the practical problem of regulating the soil water and salt status in the oasis more correctly. According to the instructions of the 20th National Congress of the Communist Party of the Soviet Union and the resolutions of the party and government on the development of cotton planting in Turkmenistan, the Uzbek Soviet Socialist Republic and the Karakal Park Soviet Socialist Autonomous Republic, the soil improvement of irrigated land in the lower reaches of the Amu Darya River has achieved some positive results so far. The water volume per unit irrigation area taken by the irrigation system from the Amu Darya River has been significantly reduced. New catchways have been built to remove excess groundwater, and the work of the old catchway network has been improved. The discharge of groundwater and salinity have increased significantly with the discharge of irrigated plots. The implementation of the instructions of the 21st National Congress of the Communist Party of the Soviet Union on the development of cotton planting industry will require the expansion of irrigation area and improvement of soil improvement in the lower reaches of the Amu Darya River. In this work, in addition to the author's personal observation and research, the research results of multiple teams of the Aral Caspian Sea comprehensive investigation team studying the region from 1951 to 1953 are also used and integrated from the above perspective. The book makes extensive use of the research results of fixed-point soil improvement conducted by Peter M. zemsky and his colleagues, ye de sergeeva, Le M. Zhukova, and Yu P. velecenko from 1951 to 1953. The materials provided by the water economy and hydraulic technology team of the investigation team led by S. Le Mirkin, N. N. favohne and A. de savarenski, under the general guidance of A. N. Kosjakov, academician of the communications Academy of the Soviet Academy of Sciences, enable the author to more accurately consider the characteristics of irrigation channels and the dynamic impact of irrigation on the overall salt status of the oasis. Le a. rastochina, T. v. zamolina, en n. ostrovnaya, VA a. timoshina, Le v. levonovsky, ye a. Kalinsky, VA I. astrahansev, and Si I. rebkin participated in these efforts. Some of the materials of the hydrological team of the laboratory of Limnology of the Soviet Academy of Sciences were used, which studied the hydrology of the modern Delta (G. f. lopagin and L. F. Flynn). The soil plant team (including en en balitsevic, F. v. yegorov and le yerodin) clarified the main characteristics of soil water and salt status in the modern Delta. The team of hydrochemistry Institute (led by G. v. Lazarev) provided valuable data of Amu Darya River culture; For the hydrochemistry of groundwater and salt lakes, some analytical materials from the physical chemistry team of the Institute of general and inorganic chemistry (EN Pu luzina, ye Fu lukiyanova) were used. When analyzing the problem of salt brought by flowing water from Delta lakes and irrigated oases, the materials of the hydrodynamic team of the Institute of mechanics of the Academy of Sciences of the Soviet Union (PIA konina, Al shikirich) provided valuable help. The team studied the problem of leaching salt from the Uzbek riverbed. When analyzing the origin of the dry saline soil in the ancient Delta, the archaeological data of the khwarazmo expedition (S. P. tolstov, B. F. andrianov) and the geomorphological and paleontological teams (A. S. Casey, A. g. eberzin) were used. Hydrogeological teams (K. F. Filatov and M. f. grobkov) provided a series of materials in hydrogeological mapping and analysis of the impact of irrigation channels on groundwater conditions and mineralization.