- The Role of Scientists from Ukraine, Russia, and Kazakhstan

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potassium fertilizers and the interaction between potassium and nitrogen fertilizers. In this connection he published a series of works: «Chemical Determination of the Need of Soils for Potassium Fertilizers» (1933), «The Effect of K on Different Soils at Different Concentrations of H, Ca and Na (1934), «The Interdependence of the Action of Potassium and Nitrogen Fertilizers» (1935), «Changes in the Content of N, P2O5, K in the Barley Yield under the Influence of Soils and Fertilizers» (1938) and others. Studying the interaction of various types of fertilizers, A.T. Kirsanov concluded as early as 1934 that «under a severe shortage of potassium, nitrogen fertilizers not only fail to increase the yield but even ruin it». He linked the effect of fertilizers to the availability of nutrients in the soil, the ratio of ions in the soil solution, soil moisture, the level of fertility, the height of the yields of previous years, the peculiarities of agrotechnics, and other factors. A major contribution to the improvement of the methodology of agrochemical research was made by Vsevolod Mavrikievich Klechkovsky (1900-1972). Among Russian scientists of the 20th century, V.M. Klechkovsky occupies an honorable place as a leading researcher in the field of agrochemistry and radioecology, who turned his fundamental knowledge to the study of atomic structure and to the development of the methodology and application of the tracer-atom method in agrochemistry and biochemistry. In his large-scale

and thorough studies, a special place is occupied by the creation and development of radioecology and the agrochemistry of radioactive fission products. These and other multifaceted studies of radioisotopes in various branches of biological and agricultural sciences gained worldwide fame and recognition. The formation and active development of agricultural radiology began with the organization by V.M. Klechkovsky in 1947 of the Laboratory of Biophysics at the K.A. Timiryazev Moscow Agricultural Academy, where talented scientists worked—A.G. Shestakov, I.V. Gulyakin, E.V. Yudintseva and others. Already within the first five years of this laboratory's work, the basic patterns of the behavior of radionuclides in soil, the extent of their transfer from soil to plants, and the magnitude of the accumulation of radionuclides in various plant organs were uncovered. Large-scale studies were subsequently conducted to clarify the conditions promoting the entry of radionuclides into plants, as well as the factors reducing the accumulation of radionuclides in the yield of agricultural crops. The results of these experiments were of great importance and remain highly relevant to this day, especially when growing plants on agricultural land that has been subjected to radioactive contamination. A bright mark in the history of agrochemistry, in the development of the national agrochemical scientific school, was left by Nikolai Sergeevich Avdonin (1903-1979). He developed the most important scientific and practical propositions in agrochemical science. Under the direction of N.S. Avdonin, multifaceted fundamental and applied research was carried out at the Department of Agrochemistry of Lomonosov Moscow State University. In the early 1950s, very detailed studies were carried out substantiating the increased effectiveness of granulated superphosphate compared with powdered superphosphate within the soil-fertilizer-plant-microorganism system. It was established that the reduction in the retrogradation of the phosphoric acid of granulated superphosphate in the soil is associated with the activation of microbiological processes in the zone around the granules, which reduces the chemical immobilization of phosphorus. The results of this research were summarized and published by N.S. Avdonin in the books: «Granulated Fertilizers» and «The Application of Granulated Superphosphate», which became widely known both in our country and abroad.

Under the direction of N.S. Avdonin, the relationship between soil properties, fertilizer application and the resistance of overwintering cultivated plants to unfavorable weather and other conditions in the winter-spring period was studied. A biochemical study of the content in overwintering plants of various fractions of carbohydrates and nitrogenous substances, the chemical composition of the ash, and a study of the activity of invertase, catalase, peroxidase and proteolytic enzymes showed that the death of these plants in winter on sod-podzolic soil occurs as a result of the negative effect on them of the unfavorable properties of the soil and of wintering conditions. The results of this research were presented in N.S. Avdonin's monograph «Questions of Farming on Acid Soils». At the Department of Agrochemistry of Moscow State University, under the direction of N.S. Avdonin, the influence of soil properties and fertilizers on the quality of plant produce was thoroughly studied. The results of the research showed that the more cultivated the soils, the better the quality of the plant produce, which was assessed according to a broad range of indicators: the content of protein substances, essential amino acids, various types of carbohydrates (glucose, sucrose, starch), vitamins (C, B1, B2), carotenes, the composition of ash substances, etc. This extensive original data was summarized and published by N.S. Avdonin in the book «Soils, Fertilizers and the Quality of Crop Produce». The development of agrochemistry was significantly influenced by the research and developments of scientists working in related fields of knowledge. In this connection, mention must be made of the prominent role of the works of V.V. Dokuchaev, A.G. Doyarenko, N.I. Vavilov, S.I. Volfkovich and V.A. Kovda. Vasily Vasilyevich Dokuchaev (1846-1903). V.V. Dokuchaev wrote that the improvement of agricultural cultivation could proceed along a correct, reliable path only through a comprehensive familiarity with soils. He studied soils with the aim of managing the processes occurring in them that determine the fertility, stability and level of yields of agricultural plants. In a number of his works on the classification and assessment of land, V.V. Dokuchaev took detailed account of the process of soil cultivation through manure application, studying the fertility of manured soils in constructing classification and assessment scales. In 1892 he wrote his famous book «Our Steppes, Then and Now» as a response to the disaster of the people—in 1891 a severe drought

struck the chernozem belt of Russia. The book analyzes the causes of the drought and sets out a plan for the transformation of nature and the reconstruction of agriculture in the chernozem belt in order to obtain high and stable yields. The system of measures developed and recommended by V.V. Dokuchaev was aimed at regulating the water economy in the steppes of Russia. He wrote that the age-old experience of local inhabitants and the scientific research carried out in the southern steppe of Russia showed that the chernozem belt was undergoing a slow, progressive desiccation. In connection with this, in the book «Our Steppes, Then and Now» V.V. Dokuchaev outlined a program of action, a system of measures to save the steppe agriculture of Russia and to eliminate the causes leading to natural disasters in the chernozem region. The main ones are: regulation of rivers; regulation of ravines and gullies; regulation of the water economy in the open steppes, on the watershed spaces; the development of standards for the ratio of areas of arable land, meadows, forests and waters; and the improvement of the system of soil cultivation in steppe farming. Everything proposed by V.V. Dokuchaev remains highly relevant today and shows that he thought in statesmanlike, strategic terms about solving the questions of national agriculture—taking into account the entire agricultural complex, applied to specific natural-geographic conditions. V.V. Dokuchaev did not limit himself to merely drawing up his plan. He achieved the organization of a special expedition, headed it, and organized a network of experimental stations, testing in practice the reality of his plan and the effectiveness of the proposed measures. The set of agronomic measures he developed was implemented in accordance with local conditions at the Kamennaya Steppe Experimental Station (now the V.V. Dokuchaev Research Institute of Agriculture of the Central Chernozem Zone), which made it possible for many years to obtain high and stable yields of grain and other crops in the chernozem steppe. V.V. Dokuchaev wrote not only of the need to create agricultural institutions for the application of the scientific propositions developed and the elaboration of the most advantageous methods for achieving success in any technical production, but also of the importance of training good agronomist specialists, for which the organization of higher agronomic educational institutes was necessary. V.V. Dokuchaev was the first to show the most important role of soil in the life of nature and man, and in his teaching it is regarded as a special natural-historical body in which, as in a mirror, the age-old interact

ions between dead and living nature, including the activity of man, are reflected. For this reason both Russian and foreign scientists call him one of the founders of the modern doctrine of the biosphere. V.V. Dokuchaev advocated the development of national zonal agronomy and opposed the blind use of the achievements of the agronomy of Western European countries. Questions of agrochemistry are also covered in the works of the renowned scientist N.I. Vavilov. Nikolai Ivanovich Vavilov (1887-1943)—an outstanding crop scientist, geneticist, plant breeder, geographer, educator and organizer of agricultural science, the founder of the doctrine of the biological foundations of plant breeding. Already in N.I. Vavilov's first works on the chemical protection of plants, and in his subsequent research on the effect of various fertilizers on plant immunity, a direct connection with agrochemistry is evident. On the basis of a series of field and vegetation experiments on the effect of nitrogen and potassium fertilizers on the immune system of plants, N.I. Vavilov concluded that the variability of immunity depending on environmental conditions—a very complex question. He confirmed this conclusion when studying the effect on plant immunity of macro- and micronutrients on new varieties of wheat and oats differing in resistance to brown and yellow rust. Among the factors capable of altering plant immunity, he included such an important agrochemical indicator as soil acidity. N.I. Vavilov always followed D.N. Pryanishnikov's doctrine of agrochemistry as the plant-soil-fertilizer system, and emphasized the great importance of mineral fertilizers for the country's agriculture. Therefore Nikolai Ivanovich received with particular satisfaction the discovery of large deposits of potassium and phosphoric-acid salts at Solikamsk and in the Khibiny Mountains. He wrote that this posed the problem of the chemicalization of agriculture in a new way—from the academic study of the mineral fertilizer industry, in the actual absence thereof, the country proceeded in practice to its wide-scale use. In N.I. Vavilov's opinion, the expansion of mineral fertilizer production—one of the essential conditions for the further advancement of agriculture. On the basis of the results of research on the effectiveness of mineral and organic fertilizers, as well as of soil liming, on the fields of collective and state farms of Leningrad Province, he identified the regions of the most effective application of fertilizers in crop rot

ations, combined with other agrotechnical methods. Therefore, in his article «Problems of Northern Agriculture» (1931), N.I. Vavilov wrote that the main condition in this respect is the chemical amelioration of soil and the application of organic and mineral fertilizers, drawing attention at the same time to the underestimation of manure in the agriculture of our country. Nikolai Ivanovich called for a differentiated approach to the application of fertilizers and warned against the stereotyped application of any measures. N.I. Vavilov noted that the chemicalization of agriculture in the country required a huge amount of systematic research work, which could be handled only by a well-organized team of agrochemists. To achieve success on any questions of agronomic science, he called for the cooperation of the efforts of scientists of various specialties with one another—plant breeders, biochemists, plant physiologists, phytopathologists. An important role in the history of the development of agrochemistry, in particular in the technology of mineral fertilizer production, was played by Semyon Isaakovich Volfkovich (1896-1980), an outstanding chemist. His multifaceted work on the technology of mineral fertilizer production exerted a substantial influence on the development of the chemical fertilizer industry. He directed research on the processing of Khibiny apatite-nepheline ores into concentrated fertilizers, fluorine salts and rare-earth metal compounds; he took part in the commissioning of the first ammonia synthesis shop and in the development of the process for obtaining and conditioning ammonium nitrate. S.I. Volfkovich initiated research into the process of urea synthesis and was an active promoter of its application. Subsequently, ammonium nitrate and urea became the principal high-quality and effective nitrogen fertilizers in domestic agriculture. Later, Semyon Isaakovich, together with his colleagues, proposed a method for producing phosphates and polyphosphates of urea and the triple fertilizer—carboammophoska. After the discovery of the huge Verkhnekamsk deposit of potassium salts, he and his colleagues proposed a technological scheme for processing sylvinites, as well as a method for the chemical processing of carnallites to obtain potassium-nitrogen and magnesium fertilizers.

The extensive theoretical and production-oriented research of S.I. Volfkovich, his students and colleagues, served as the basis for the creation and development of the industry for the production of defluorinated phosphates, ammonium and sodium phosphates, mono- and dicalcium phosphates and others, which became widely used as feed additives for livestock farming. S.I. Volfkovich assigned agrochemistry an important place among other branches of knowledge and noted that, by combining its efforts with biology and physics, it (agrochemistry) would make it possible to reveal the essence of the laws governing the development of organisms. For this reason such related, «hybrid» sciences as biochemistry, agrochemistry, soil chemistry, the biochemistry of microorganisms, biogeochemistry, and the chemistry of food and feed products, etc., are called upon to solve the most important theoretical and practical problems of studying the cycling of nutrient elements in nature and the processes of growth and fruiting of plants, animals and microorganisms, with the aim of actively influencing their course in the desired directions and with the desired intensity. As early as 1962 S.I. Volfkovich called not only for an increase in the pace of mineral fertilizer production, but also identified the main directions in the development of their range and the improvement of their quality: a substantial increase in the concentration of nutrients in fertilizers; a greater output of fertilizers in the form of bulk blends and complex fertilizers, including both macro- and micronutrients; the expansion of the production of boron, copper and manganese fertilizers and the organization of the production of molybdenum, cobalt, zinc, iodine and other micronutrient fertilizers; the release of part of the nitrogen and complex fertilizers in liquid form; the release of part of the chlorine-free potassium fertilizers; and the organization of the production of slowly soluble (long-acting) nitrogen fertilizers and complex fertilizers based on the products of urea polymerization with various substances, etc. A considerable part of these directions was implemented in practice in the production of mineral fertilizers. In the second half of the 20th century, the ecological direction of research in agrochemistry developed. A substantial influence in this direction was exerted by the works of Professor Viktor Abramovich Kovda of Moscow University (1904-1991), who, through his classic works on the connection between agrochemistry and geochemistry, created a new direction of research—the agrogeochemical direction. A characteristic feature of V.A. Kovda's works consists in the fact that he considers

the global, fundamental problems of the soil cover, its biospheric and geochemical functions, from the standpoint of ensuring the survival of humanity on the planet, while solving pressing practical problems. He completed and published a number of important scientific works containing new fundamental propositions of agrochemistry. In the work «Fundamentals of the Doctrine of Soils» (1973), V.A. Kovda writes that cultivated (artificial) biogeocenoses (i.e. agrogeocenoses), directed by the mind and labor of man, produce essential organic products of food and industrial significance. Man obtains the maximum sustainable biological output from biogeocenoses only when he acts correctly on the links of this complex system... However, culture ecosystems can be effectively managed only when the mechanism, the essence and the history of the relationships between soil, organisms and environmental conditions are correctly understood. Soil fertility—the main condition for human life on Earth. The optimization of the chemical composition of soils by means of agrochemical measures not only increases soil fertility but also prevents the occurrence of many endemic diseases in humans and animals. The universal and most important result of the biological cycling of substances and the biogenic transformation of rocks, and the synthesis and mineralization of organic substances, was the widespread separation on land of the humus horizon. It is precisely this thin envelope, the energetically and biologically most active part of the soil cover, that determines the level and potential possibilities of its fertility. From the standpoint of agronomic practice and the physiology of plant nutrition, organic matter performs a multifaceted function in agro-biogeosystems: as a peculiar form of complex fertilizer; as humic substances forming an agronomically valuable, water-resistant soil structure that promotes the creation of favorable water-air properties for plants. Emphasizing the importance of humic substances in farming practice, V.A. Kovda draws attention to the need to use a set of measures for preserving and reproducing humus in the soil: the systematic application of organic fertilizers; a system of correct crop rotations; correct grass sowing, in particular the regular cultivation in crop rotations of legume grasses or legume-cereal grass mixtures; the periodic application of green manure;

liming, which enriches the soil with calcium compounds and activates the processes of synthesis of humic acid compounds, etc. V.A. Kovda noted that the time is coming for the real possibility of the gradual and increasingly rational management of the supersystem nature-society within the framework of the entire planet. And these circumstances compel us to consider with particular care the problems of one of the most important components of nature—the soil cover, in the light of its improvement, rational use and protection, since the normal functioning of the biosphere as a whole is linked to its existence and normal functioning. The natural fertility of soils, without the addition of mineral and organic fertilizers, cannot ensure the sustainable production of grain-crop yields exceeding 25-30 centners per hectare (c/ha), even on the best soils. Without the application of fertilizers on podzolic, gray forest and drained bog soils, yields will not exceed 8-12 c/ha; on irrigated sierozems, chernozems or chestnut soils—25-30, and more often 15-20 c/ha. To obtain grain yields on the order of 50-60 and especially 70-100 c/ha, a favorable biochemical soil background is needed, along with a high provision of the soil with energy (humus content of 5-6%), moisture, mineral nutrition elements and carbon dioxide. Viktor Abramovich associated the successes of future agriculture with the wide application of mineral fertilizers, noting that industrial fertilizers remain and will remain in the foreseeable future one of the main levers for increasing the productivity of agricultural production. At present there is no reasonable alternative to their application. He wrote: «One of the tasks of modern agrochemistry is the comprehensive increase in the effectiveness of mineral fertilizers together with the study of the ecological consequences of the intensive chemicalization of agriculture... In developed countries, where highly productive agricultural production is based on the intensive application of fertilizers, the latter become an ecological factor that intensifies, through soil-ground waters, plants and soil microorganisms, the cycling of biophilic elements». Undoubtedly, our contemporaries and descendants must remember and be grateful to the many well-known scientists who actively developed the fundamental propositions and methodology of agrochemical science in the 20th century. To the names of researchers already mentioned earlier must be added the names of other scientists of the CIS countries.

Highly authoritative and well known in Ukraine was Pyotr Antipovich Vlasyuk (1905-1980)—Honored Scientist of the Ukrainian SSR, academician of the All-Union Academy of Agricultural Sciences (VASKhNIL) and of the Academy of Sciences of the Ukrainian SSR. His creative activity was distinguished by the multifaceted nature of his research: the physiology of plant nutrition, soil science and geochemistry. Many of his works were carried out in the direction of clarifying the essence of the influence of organic substances, biogenic macro- and micronutrients, and physiologically active substances on the growth and development of plants. In studying plant nutrition, he was the first in Ukraine to apply the tracer-atom method, which enabled him to reveal the physiological features of the participation of phosphorus compounds in the synthesis of carbohydrates in various organs of sugar beet, as well as the role of sulfur in the biosynthesis of amino acids and proteins. P.A. Vlasyuk paid much attention to clarifying the biological role of manganese, molybdenum, boron and zinc in the vital activity of plants. This research was carried out from various perspectives: as biogenic elements in plant nutrition, as components of enzyme systems, and as activators and inhibitors (depending on concentration) of the processes of plant growth and development. Alexander Ivanovich Dushechkin (1874-1956)—Honored Scientist of the Ukrainian SSR, founder of the Ukrainian scientific agrochemical school. He devoted much attention to studying the dynamics of changes in the forms of nitrogen in soil depending on fertilizer application and other factors; the forms and dynamics of phosphorus in soil and the ways of increasing the effectiveness of phosphorus fertilizers; the entry of nutrients into plants; rational methods of fertilizer application; the most effective use of local fertilizers; and other pressing problems of agrochemistry. Ivan Georgievich Rozhdestvensky (1901-1977). He made a great contribution to the development of agrochemical science and to the development of fertilizer systems in sugar-beet crop rotations. He substantiated the conditions for the effective use of potassium salts and various forms of nitrogen and phosphorus fertilizers depending on soil-climatic conditions, and the advisability of combining chlorides and sulfates of potassium, sodium, magnesium and calcium, ensuring an increase in yield and an improvement in the quality of sugar beet. He carried out important research on the application of concentrated fertilizers and bulk blends to sugar beet.

Nikolai Konstantinovich Krupsky was a prominent figure among Ukrainian scientists. He devoted much attention to the development of fundamental agrochemical research. Under his leadership, studies were carried out to clarify the nature of soil acidity, which made it possible to develop a new direction in soil liming. He was the first to propose the use of electrometric methods for determining ions in soils, which found wide application in scientific research on agrochemistry and soil science. Under the leadership of N.K. Krupsky, fundamental studies were carried out on the agrochemical indicators of soil fertility in Ukraine and their changes under the influence of fertilizers and agricultural technique. Yuri Konstantinovich Kudzin (1907-1978). The main direction of his research was the development of the agrochemical basis of a fertilizer system for crop rotation crops under long-term application. He established that with long-term systematic application the effectiveness of superphosphate decreases, the positive effect of nitrogen and potassium fertilizers increases, and a need for zinc arises. He was the first to study the effect of long-term fertilizer application on biological processes in chernozem soils. Over the past decades, a great contribution to the development of agrochemical science was made by Ukrainian scientists N.M. Gorodny, B.S. Nosko, A.G. Serdyuk, S.A. Balyuk and others. In the Republic of Belarus, a great contribution to the development of agrochemical science was made by Tamara Nikandrovna Kulakovskaya (1919-1986) — academician of VASKhNIL, corresponding member of the Academy of Sciences of the BSSR. She carried out thorough research on improving the methodology for developing the fundamental principles of agrochemistry and the practice of effective use of organic and mineral fertilizers. She devoted much attention to a comprehensive assessment of the state of soil fertility, the study of nutrient balance dynamics in Belarusian agriculture, and the improvement of methods for forecasting agricultural crop yields. The study of the relationship between the magnitude of agricultural crop yields and soil properties led to the need to develop optimal soil fertility indicators for agroecosystems. Differentiation of fertilizer doses taking into account the biological requirements of crops, soil fertility and agricultural technique allowed T.N. Kulakovskaya to scientifically substantiate and develop methods for determining fertilizer doses for the planned yield.

T.N. Kulakovskaya not only carried out extensive agrochemical research, but also performed a great deal of scientific and organizational work, serving as director of the Institute of Soil Science and Agrochemistry. It is hard to overstate the significance and productivity of the fundamental agrochemical research of Sergei Nesterovich Ivanov, a corresponding member of the Academy of Sciences of the BSSR. Developing K.K. Gedroits' teaching on the soil absorbing complex, he studied the dependence of soils' absorption capacity on the reaction of the medium and on the type and concentration of cations. He devoted much attention to improving the methods of agrochemical research. Under his leadership, methods were developed for studying potassium nutrition in plants using radiolabeled ⁴²K and ⁸⁶Rb as potassium tracers, which made it possible to begin studying the processes of plant nutrition and the uptake of nutrients from fertilizers and soil by plants under the combined action of nitrogen (¹⁵N), phosphorus (³²P) and potassium (⁸⁶Rb) at a higher theoretical level. Robert Tenisovich Vildflush (1906-1972) left a notable mark on the history of the development of agrochemical research in Belarus. His research was distinguished by its versatility: liming of soils, the use of magnesium-containing lime fertilizers, biochemical questions of plant nutrition, the influence of the Ca to Mg ratio on nitrogen metabolism in plants, and others. Under the leadership of R.T. Vildflush, fundamental research was carried out for the first time in Belarus on developing the physiological basis and practical aspects of localized and other methods of fertilizer application. He also devoted attention to developing methods for the effective use of micronutrient fertilizers in the cultivation of legume crops (clover, alfalfa, forage beans, sweet clover). For a long period (1973-1991) the Department of Agrochemistry at the Belarusian Agricultural Academy was headed by Alexander Arsenyevich Kalikinsky (1915-1993). He devoted much attention to research on the effectiveness of localized fertilizer application on sod-podzolic soils of various particle-size composition and degree of cultivation. He established that the best effect from localized fertilizer application is obtained on loamy soils, while on sandy soils this method shows a weaker effect (this method is less effective). A.A. Kalikinsky summarized the results of this research in his doctoral dissertation. On his initiative, long-term stationary experiments were established, in which the effectiv

-iveness of fertilizer application methods in field and forage crop rotations depending on the fertility level of sod-podzolic soils. Over the past decades, a great contribution to the development of agrochemistry in the Republic of Belarus was made by academicians I.M. Bogdevich, V.V. Lapa, A.R. Tsyganov, as well as by professors I.R. Vildflush, T.F. Persikova and others. Much attention to the development of agrochemistry was devoted by scientists of the Republic of Kazakhstan, especially in the southern part of the country under conditions of irrigated agriculture. Among them, Kenzhes Imangazievich Imangaziev is well known. He established a number of important patterns in the action of fertilizers (on different soil types): the effectiveness of phosphorus fertilizers increases from sierozems to mountain chestnut soils, while that of nitrogen fertilizers, conversely, increases from chestnut soils to sierozems. On meadow soils, a weak responsiveness of sugar beet to nitrogen fertilizers was noted. On this crop, a high effectiveness of mineral fertilizers under irrigation conditions was established. When cultivating sugar beet after grasses, the need for phosphorus and potassium fertilizers increases, while that for nitrogen fertilizers decreases. High effectiveness was established for stubble green manure — chickling vetch, peas, and common vetch — when sown after the harvest of winter wheat. Based on experimental data, K.I. Imangaziev developed a fertilizer system for the sugar-beet crop rotation. Important agrochemical research under the conditions of Kazakhstan was carried out by Anna Terentyevna Ponomaryova. Her research was aimed at increasing the effectiveness of fertilizers taking into account the biological properties of the crop and soil fertility, in particular the content of mobile forms of nitrogen, phosphorus and potassium in the soil. She devoted much attention to studying the phosphate regime of soils under the conditions of southern Kazakhstan. This allowed her to establish a complex relationship between the yield of agricultural crops, the level of soil fertility, and the fertilizer dose. In doing so, a certain correlation was noted between the effectiveness of phosphorus fertilizers and the content of mobile phosphorus in the soil. Taking this into account, A.T. Ponomaryova developed phosphorus fertilizer doses for the main crops, determined the phosphorus balance in the agriculture of Kazakhstan, and the republic's requirement for phosphorus fertilizers. Under the irrigated conditions of Southern Kazakhstan, the work of Bayan Sapargaliyevich Basibekov plays a certain role in the development of agrochemical research. Based on research carried out in long-term stationary experiments, he showed that the application of a complete

complete (NPK) mineral fertilizer in the crop rotation ensures an increase in both the potential and effective fertility of irrigated light chestnut soil, and, on this basis, the production of high and stable yields of crops in the sugar-beet crop rotation: alfalfa hay, sugar beet roots, and winter wheat grain. Based on experimental data, B.S. Basibekov calculated that, under the conditions of Southern Kazakhstan, with irrigation of light chestnut soils, in order to obtain high yields of crops with good product quality and to maintain a non-deficit balance of humus and phosphorus, the removal of nitrogen over a crop-rotation cycle should be compensated at 60%, and phosphorus depending on the soil's supply of mobile phosphorus: at a low level — 120%, medium — 100%, high — 60%. Where these soils have a high potassium supply, its removal by the harvest should be compensated at 25%. Over the past decades, scientists of the Republic of Kazakhstan have made a great contribution to the development of agrochemical science. Among them are R.E. Yeleshev, V.G. Chernenok, S.B. Ramazanova, A.S. Saparov, S.Z. Yelubayev and others. Among the agrochemist scientists of Moldova who made a significant contribution to the development of the science in the twentieth century, the following deserve mention: Pyotr Andrianovich Kurchatov (1898-1955). He developed theoretical principles and practical methods for managing soil fertility, increasing crop yields and product quality. Konstantin Lukyanovich Zagorcha. He devoted much attention to research on plant nutrition and the role of fertilizers in obtaining high yields and quality of agricultural crops, and to developing methods for increasing fertility and improving the physicochemical, physical and biological properties of chernozem soils. Stepan Grigoryevich Bondarenko. His contribution lies in the development and use, in agrochemistry and viticulture, of mathematical methods and computer technology, a systems approach, and methods for calculating the energy intensity of grape-production technologies. Mikhail Aleksandrovich Tsurkan devoted his creative career to developing fertilizer systems, particularly the agrochemical and technological aspects of applying organic fertilizers, and their effects on the restoration of soil fertility, increased crop productivity, improved product quality, and the solution of environmental problems. Among the agrochemist scientists of Moldova, a prominent place is occupied by Simon Ivanovich Toma, Serafim Vasilyevich Andriesh, Pyotr Vasilyevich Kordunyanu, and Porfiry Nikolayevich Kordunyanu.

Scientists — agrochemists of the Baltic republics carried out important agrochemical research. In Lithuania: K.I. Plesyavichyus, P.K. Vasinauskas, A.I. Zalins, Ya.B. Adomavichute, and others; in Latvia: P.D. Barbanis, G.Ya. Rinkis, V.F. Nollendorf and others. In Estonia: O.G. Hallik, H.A. Kyarblane, R.I. Toomre. Among the Transcaucasian republics in the twentieth century, particularly active and versatile agrochemical research was conducted in the Republic of Azerbaijan. Thus academician D.A. Aliyev devoted much attention to the development of the theory of plant nutrition, photosynthesis, metabolism, and the formation of high productivity in cultivated plants. Z.R. Movsumov devoted his research to the practice of nitrogen agrochemistry; R.K. Guseynov and M.I. Dzhafarov to improving methods for studying the phosphate regime of soils and studying the effectiveness of phosphorus fertilizers; T.A. Aliyev and H.O. Gyulakhmedov to the agrochemistry of the potassium regime of soils and the effectiveness of potassium fertilizers. A.N. Gyulakhmedov, N.A. Agayev, and B.K. Shakuri devoted their research to the state of the micronutrient regime in soils and the effectiveness of micronutrient fertilizers, while F.G. Akhundov and P.B. Zamanov worked on fertilizer systems for cotton and vegetable crops. Among Armenian scientists of the twentieth century, active agrochemical research was conducted by G.Sh. Aslanyan, B.N. Astvatsatryan, N.O. Avakyan, Ya.S. Harutyunyan, and G.B. Babayan. In the development of agrochemical science in Georgia, a great contribution was made by Sh.R. Tsintsadze, G.N. Urushadze, I.D. Gamkrelidze, I.A. Nakaidze, M.L. Baziava, O.G. Oniani, I.F. Sarishnili, O.Yu. Zardalishnili, V.P. Tsanava, G.N. Margvelashvili and others. Among the republics of Central Asia, a special place in the development of agrochemical research is occupied by Uzbekistan. In this connection, the works of I.I. Madraimov, B.I. Machigin, N.N. Zelenin, G.I. Yarovenko, P.V. Protasov, B.M. Isayev, T.P. Kirakhunov, and D.S. Sattarov are of interest. The establishment of agrochemistry in Tajikistan is associated with the names of I.N. Antipov-Karatayev, I.M. Lipkind, and A.M. Meshcheryakov. A special role in the development of agrochemistry in this country was played by the research of Kh.D. Dzhumankulov. A certain contribution to the development of agrochemistry in Turkmenistan was made by K.I. Semergey, A.S. Ibragimov, G.A. Dyuzhev, and in Kyrgyzstan — by N.G. Korneva.