On the basis of field route researches, natural-caused and anthropogenic factors of the soil cover transformation of the Caspian Sea northern coast are defined; the features of the morphological and chemical properties of soils are revealed, and the degree of their degradation is determined. A map of soil degradation at a scale of 1:100 000 was created. Geoinformation technologies and remote sensing materials were used to compile the map.

The correct natural agricultural zoning of the territory is one of the foundations promoting the improvement of the use of land resources, and therefore the general subsidence of agriculture. The scientifically grounded natural agricultural zoning can serve as a basis for the proper allocation of the branches of the farming, for the implementation of specialization, for the development and introduction of rational crop rotations and appropriate agricultural crops, for the application of advanced agricultural-technical, anti-corrosive and agro-meliorative techniques. The article deals with the issues of natural agricultural zoning of the territory of the Ararat soil district of the Republic of Armenia. The characteristics of soil fertility with the goal of the most rational study of lands in the agricultural production is given based on the existing materials on the study of the soil cover, the results of new studies and details of the natural agricultural zoning of the land fund of the given district. On the basis of comprehensive analysis and of existing materials on climate, relief, exposure, soil-forming rocks, soils and other economic and production factors, a scheme of natural-soil zoning and agro-production grouping of soils of the Ararat soil district of the RA has been developed, and the characteristics of fertility of the identified natural-soil regions and groups of soil, as well as the main ways on the increase of the productivity and fertility of lands has been presented. It is established that they can be used during the planning of agricultural and zootechnical, meliorative, agro-meliorative and soil protection arrangements envisaged for the improvement of the use and increase of productivity of the land fund of the republic.

An impact of microrelief on salinization process in the soils of the Ujar Support Point was studied and a salinisation map of the same zone was compiled in the article. The researches show that the salts quantity in microhollows is more than in the areas. The soils are salinized to an average, strong and verystrong degree in the zone. But the unsalinized and weak salinized soils spread in the plane areas.

Complex melioration of meadow solonchaks in the Almaty region's saline belt was carried out by regulating the water-salt regime, the level of groundwater and their mineralization under conditions of deep (2,4-2,8 m) horizontal drainage, by washing, cultivating crops and conducting water desalination. Changes in meadow solonchaks during their long-term melioration are considered in the article.

The article presents the results of the study of the soil and vegetation cover of the territory adjacent to the production complex of the zinc plant. Studies have shown the negative impact of plant emissions on soil and plants. So, over a considerable area, the surface of the chernozem soil is devoid of vegetation, subjected to erosion processes in the form of deep debris, irrigation ditches and continuous washing of soil into the Tikhaya River. The preserved arboreal and shrubby plants outside the plant are covered with brown-brown burn marks, sometimes they fell out. The main plant emissions that pollute the soil, plants and affect the biota are heavy metals. Priority pollutants are zinc, lead, copper and cadmium. Thus, the gross forms of these elements in the soil exceed the maximum permissible concentration in hundreds of times, mobile in 6-7 times.

For 53 years of using irrigated light chestnut soil without fertilizers, the content of mobile phosphorus and exchange potassium decreased in the 0-20 cm soil layer by 22-30 % and 4-8 %, respectively. When using the mineral fertilizer system, the content of mobile phosphorus increased by 121-145 % (24-34 mg/kg soil), exchangeable potassium - by 15-29 %. The maximum accumulation of mobile phosphorus and exchangeable potassium was noted in variants of joint application of mineral fertilizers and manure - 240-278 and 27-43 %, respectively. The nitrogen content of nitrates in the soil was determined to a greater extent by the hydrothermal state of the agrosystem than by fertilization.

The calculation of the recoupment of organic and mineral fertilizers and their amount (NPK) per kg of active substance relative to the yield of spring wheat according to the statistical materials of the time series for 1964-2016 is considered. With the joint use of fertilizers, their organic counterparts have a payback of 13.33-18.75 kg of grain, mineral - 10.62-15.38 kg, and the sum of NPK - 5.34-7.02 kg of grain per 1 kg active substance.

The paper presents a comparative analysis of the application of different types of mineral fertilizers in cultivation of winter barley on ordinary grey soil, grown in conditions of low concentration of nitrogen. The use of mineral fertilizers improves soil nutrition regime, has a positive effect on growth, development (r = 0.948), and winter barley yield and provides conventionally net income. The application of phosphorus fertilizers containing sulfur improves plants growth and development (r = 0.943), increases productivity of winter barley.

In the paper, topical issues related to the study of the nature of the alkalinity of the rice fields of the Akdalinsky irrigation array are considered. Carbonate, borate, organic alkalinity and their dynamics during the growing season of rice during drip irrigation and irrigation by the method of constant flooding were analyzed.

The results of two years of research have shown that the application of nitrogen fertilizers in top dressing against the background of different availability of soils with mobile phosphorus had a significant effect on the change in crop structure and on the yield of sweet sorghum. It is shown that the yield of grain in varieties of sweet sorghum increased on fertilized variants from 13.6 to 42.9 %.The highest grain yields (39.7 c/ha in the Kazakhstanskoye grade 16 and 45.6 c/ha in the Kazakhstan 20 grade) were obtained on backgrounds with increased soil availability by mobile phosphorus. The excess over the control variant was: on the height of the plants - 14.7 17.1 % for the variety Kazakhstan 16 and 10.9-12.4 % for the grade Kazakhstan 20; for raw biomass, respectively, 14.3-24.8 % and 15.0-23.7 %, and by weight of 1000 grains, respectively, 22.8-29.3 % and 12.3-28.8 %.The results obtained two years of research showed that the application of nitrogen fertilizers in the fertilizer on the background of various security of soil phosphorus had a significant effect on the change in the structure of crops and grain yield of sweet sorghum.