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Relevance. Cultivation of crops using No-till technology in the Stavropol Territory and other regions of our country is becoming more widespread. However, the expansion of this technology is hampered by fears that without tillage Russian soils, mostly heavy in mechanical composition, can overcompact, which will lead to a deterioration in their physical properties and, as a result, a decrease in the yield of cultivated crops.Methods. In 2013–2020 on the experimental field of the North Caucasian Federal Scientific Agrarian Canter, located in the zone of unstable moistening of the Stavropol Territory, on ordinary chernozem studies were carried out, the purpose of which was to establish the effect of long-term use of the No-till technology on the water permeability and accumulation of moisture in ordinary heavy loamy chernozem of the zone of unstable moistening of the Stavropol Territory. In the experiment, a four-field crop rotation was studied: peas — winter wheat — sunflower — corn. In one case, all crop rotation crops were cultivated according to the technology recommended by the scientific institutions of the Stavropol Territory with tillage, in the other case, according to the No-till technology, in which the soil was not cultivated for two crop rotations (8 years).Results. During two rotations of crop rotation in the No-till technology, the water resistance of soil aggregates increases and, on average, over the years of the experiments, 30.4 pcs./m2 of earthworms lived in it, which is 4.0 times more than in the soil cultivated according to the recommended technology. The water permeability of ordinary chernozem in No-till technology after eight years of research (in autumn 2020) was 7.18, and in cultivated soil —5.17 mm per minute, which is 38.9% lower. These indicators ensured the accumulation and preservation of 133 mm of productive moisture in a one and a half meter soil layer by the time of flowering of spring crops and earing of winter wheat using the No-till technology, according to the recommended technology — 101 mm.

Relevance and methods. Sowing of agricultural crops using direct seeding technology is becoming more widespread in the fields of the Stavropol Territory and other regions of our country. In the first years of the development of this technology, changes in the species composition of weed vegetation and increase the infestation of cropsare possible, in this regard, effective protection of crops from weed vegetation plays an important role in increasing the yield and economic efficiency of crop cultivation. In 2018–2020, at the experimental field of the North Caucasus Federal Scientific Agricultural Center, located in the zone of unstable moisture of the Stavropol Territory on ordinary chernozem, studies were conducted to identify the effectiveness of the use of soil herbicides in sunflower crops sown at various times (April 5–10, April 25–30 and May 15–20) using direct seeding technology. In the experiment, the sunflower was sown in the studied time with the use of only a continuous herbicide 5–7 days before sowing and with the use of the same continuous herbicide in combination with the introduction of soil herbicides after sowing. Results. On average, over the years of research, it was found that the use of a continuous herbicide is most effective 5–7 days before sowing, followed by the use of a tank mixture of soil herbicides in the post-sowing period when sowing the crop in the second decade of May. This scheme of herbicide application, combined with the postponement of the sowing period to May 15–20, reduces the number of growing weeds in crops during the growing season to 8–19 pcs./m2 and increases the yield to 2.32 t/ha.

Relevance. The rate of destruction of chernozems in the steppe zone as a result of deflation is very high. There is a threat of their loss of the humus horizon. To optimize the complex of protective measures, it is necessary to establish the regularities of the formation of wind resistance of these soils.Methods. The seasonal dynamics of the structure of the upper layer (0–5 cm) of chernozems of the steppe zone of the Lower Volga region and the Central Pre-Caucasus in the network of forest belts is studied. The aggregate composition was determined by fractionation of an air dry sample. The wind resistance of the soil was assessed by the total content of particles with a diameter of less than 1 mm.Results. It has been established that the open surface of southern carbonate chernozems is deflationary dangerous at any time of the year. Two spraying peaks were revealed — in early spring and before harvesting grain crops. In the first period, the content of particles with a diameter of less than 1 mm was 33–47%, in the second — 60–61%. Shelter forest belts reduced soil spraying in the zone of effective influence. A change in the internal structure of the deflationally dangerous fraction was detected during the year. The disintegration of large aggregates and an increase in the volume of smaller ones were observed. By the harvesting period, the number of particles with a diameter of 0.5–1.0 mm decreased by 1.7–2.6 times compared to the spring. Number of aggregates with a diameter of 0.1–0.5 mm, most strongly blown by the wind, increased by 1.3–1.8 times. The total dispersion of ordinary chernozem is almost two times lower than that of southern chernozem. However, the amount of particles with a diameter of 0.1–0.5 mm in the deflationary dangerous fraction of southern carbonate chernozem in the spring period is 37%, during the harvesting period — 50–56%. And in ordinary chernozem, already since the spring, there are more than 55% of such particles, in the future their number increases to 60%. As a result, by the harvesting period, the danger of a fraction with a diameter of less than 1 mm becomes the same for both subtypes of chernozems. This requires adjusting the complex of protective measures.

The specific features in accumulation and distribution of organic carbon and nitrogen in the aggregates of typical, ordinary, and southern chernozems (Protocalcic Chernozems, Endocalcic Chernozems, and Pantocalcic Chernozems, respectively) during the transition from conventional farming to a no-till system are evaluated. For this purpose, the contents of organic carbon and nitrogen were determined in different aggregate size fractions (>10, 10–2, 2–1, 1–0.25, and

The existing technology of soybean cultivation with mandatory tillage is quite expensive, when up to 30 % or more of the total costs are spent on preparing the soil for sowing, and most of them are spent on fuel and lubricants, which are becoming more expensive every year. The purpose of the research is to determine the effect of the technology recommended by scientific institutions and the technology of soybean cultivation without tillage with the introduction of various doses of mineral fertilizers on its yield and agrophysical properties of ordinary chernozem in the zone of unstable moisture in the Central Ciscaucasia. The influence of soybean cultivation technology without tillage, depending on the doses of mineral fertilizers, on its growth, development, yield and agrophysical, chemical and biological properties of ordinary chernozem has been studied, and an economic assessment of the studied agricultural practices has been given. Cultivation technologies and applied fertilizers did not significantly affect the quality of soybean seeds. The oil content in soybean seeds for both technologies and all doses of fertilizer application on average over the years of research was in the range of 19,8–20,3 %, protein for the same variants of the experiment contained 41,3–41,7 %, and all differences in these indicators were not statistically significant. When cultivating soybeans using No-till technology the cost of purchasing and applying a continuous herbicide increases by 1280 rubles/ha or by 49,4 % in relation to the recommended technology. However, the recommended technology significantly increases production costs for the purchase of fuel and lubricants – by 3,276 rubles/ha or 232,0 %, the wage fund by 824 rubles/ha or 93,4 %, depreciation and repair of equipment by 891 rubles/ha or 47,0 %. Thus, the biggest economic efficiency has been obtained when using the technology of soybean cultivation without tillage and without applying mineral fertilizers.

The application of direct seeding technology on typical and ordinary chernozems in the European territory for four years has resulted in a significant increase in the content of soil organic matter in regions with sufficient moisture supply and some tendency of its in regions with insufficient moisture supply (Stavropol region). A tendency for an increase in the available phosphorus and exchangeable potassium contents has also been observed. The yield of crops and profitability of production in the course of long-term (> 7 yr) application of direct seeding are approximately 30% higher than in the case of traditional technologies. Application rates of glyphosate-containing herbicides to control weeds can be significantly reduced in the case of using cover crops, modern biochemical methods, and strict compliance with the technology of herbicide application. Taken together, these measures ensure an increase in the number and species diversity of microorganisms that can suppress pathogenic microflora significantly reducing the damage to plants from diseases and pests.

This article presents the results of research on the impact of no-till technology on the natural bulk density and macro- and microaggregate composition of the topsoil (0–20 cm) in different subtypes of chernozems before sowing and during the growing season. Haplic Chernozems (Loamic, Aric, Pachic) and Haplic Chernozems (Loamic, Aric) were studied. For all chernozems, improvement of physical properties was recorded when no-till was introduced in comparison with the control. Four and six years of crop growing without tillage did not cause any compaction of Haplic Chernozems (typical and ordinary subtypes). On the plots with direct sowing, the microaggregate composition of typical chernozems was characterized by a higher proportion of coarse fractions (>50 µm) in comparison with the control. Probably, this indicates the development of microaggregation similar to that under natural cenoses, which are characterized by a relatively high content of the fraction 50–250 µm, upon the transition to no-till. In all subtypes of chernozems under no-till, the water stability of aggregates increased. The share of agronomically valuable aggregates in typical chernozem also increased, which may be associated with an increase in the input of water-soluble organic matter into the soil during no-till, because this technology excludes translocation of plant residues into the soil. In southern chernozems, this effect was manifested only for fractions >7 mm, while water stability of finer aggregates was mainly due to the calcium content regardless of the type of tillage.

The functional role of nitrogen in the formation of crop yield on chernozems under conditions of traditional and direct seeding (DS) cropping systems is considered. In the course of long-term experimental studies of DS cropping system on chernozems, considerable experience has been gained and has found efficient practical application. It is shown that the effect of nitrogen as the most important element in the composition of humic substances influencing the fertility of chernozems depends on the variability of environmental factors, the forms and rates of nitrogen fertilizers, the rotation systems, and the soil treatment technologies. The DS cropping system has been tested for 4–10 years on experimental fields of the Stavropol Agricultural Research Institute and in a number of farms in Stavropol region. The obtained data on the yields of cereal crops and the application of fertilizers attest to the importance of the formation of a mulching layer of plant residues on the surface of ordinary and southern chernozems in the DS systems. This layer contributes to a gradual accumulation of nitrogen, protects the soil from erosion, and increases the number and mass of earthworms. Nitrogen in the DS cropping systems on chernozems in Russia is characterized by the high mobility and the capacity for considerable transformation. In this context, further investigations and special experiments are necessary to gain better knowledge of the behavior of nitrogen in different cropping systems. In particular, the relationships between nitrogen fluxes, agrophysical soil properties (aggregate-size distribution at the macro and micro levels), and specificity of the organic matter in different subtypes of chernozems under different cultivation technologies have to be clarified. In general, the role of DS cropping systems in farming practices has become more significant in the recent years; application of the DS cropping system is considered a positive factor in maintaining and restoring soil fertility.

The research was carried out at the experimental field of the North Caucasus Federal Research Center. In the field, years of experience, founded in 2012, in crop rotation of soybean-winter wheat-sunflower-corn all crops cultivated on the recommended scientific institutions technology soil treatment, and these same crops in the same crop turnover has grown by No-till technology. The recommended technology of maize cultivation consisted of soil double tillage by the heavy disk tools to the depth of 0.120-0.140 m immediately after harvesting the previous sunflower, winter plowing at 0.200-0.220 m, early spring harrowing, pre-sowing cultivation and sowing with an Optima seeder. In the No-till technology, the soil was not treated and ten days before corn sowing, the plots were sprayed with a continuous herbicide Rap 600 at a dose of 2 l/ha. The research showed that better accumulation and conservation of moisture can be provided during the flowering of maize with the content in the soil layer of 1.5 m at the depth of 34 mm, or 18.1% more moisture than usage of the technology with tillage which is recommended by scientific institutions. It contributes to a significant increase of 0.42 t/ha, or 12.0% in crop yield by using this technology.

Intensification of agriculture leads to development and implementation of new soil conservation technologies that reduce degradation processes, as well as the development of methods for monitoring and controlling these technologies. Spectral indexes method as one of the methods of remote sensing is one of the most modern methods for solving this problem. This research was conducted on three production fields located in the territory of the Budenovsky district of the Stavropol territory, where plowing with the layer turnover and no-till technology were used. Aim of this research is analysis of the possibility of using 8 spectral indices to identify different types of soil cultivation. The study found that the most informative differences between tillage systems are provided by NDTI, STI and NDI7, which use the SWIR 2 spectral range for calculations. In addition, the classification of objects based on these indexes by the K-means method gives the highest accuracy.

The paper discusses the impact of direct seeding technology on volumetric weight of arable layer, content (%) of air-dry and water-resistant aggregates (mm), as well as agronomically valuable aggregates during dry sifting The fact of using the direct seeding technology for four years in grain crop rotation did not lead to an increase in volumetric weight of an arable horizon. This increases the content of dry agronomically valuable aggregates and the coefficient of structure increases. The direct sowing positively affects the water-resistant structure of typical chernozem, increasing the content of water-resistant aggregates in dry fraction > 10 mm from 68.7% (plowing option) to 80.7%.

The variability of morphometric indicators of typical chernozems is considered based on long-term field experiment in a grain 4-field crop rotation (winter wheat, corn, barley, peas) to assess the impact of plowing as a traditional farming system that uses soil treatment and no-till, in which plowing is not used. On the example of four experimental fields (each with an area of 2.4 hectares), the variation of indicators associated with the features of the soil cover structure and the applied farming systems was revealed. The tillage leads to an increase in the thickness of the soil profile leached from carbonates, and direct sowing leads to its decrease. The highest variability degree is found in the boiling depth of soil. It is shown that the tillage leads to the homogenization of the soils surface layer and the transformation of the soil cover structure, as a kind of ”insurance system " against weather risks reducing its effectiveness. The direct sowing usage leads to the restoration of degraded properties and natural of soils heterogeneity in the soil cover structures, which can be considered as a process aimed at ecological improvement of both specifiс soil sites and the soil cover structures. The mutual influence of the soil cover structure and agricultural systems can be traced in time and space. The soil structure and the cultivated crops yield related to the sustainability of agrosystems to adverse climatic conditions and other risk. For these it is necessary monitoring soil as the basis for the qualitative assessment of soil and selection of the most optimal directions of agriculture development, a new technologies development in the production of agricultural products.

The influence of different systems of soil cultivation is considered - traditional (recommended) technology and direct sowing, which is increasingly used under dry conditions of the region. The rehabilitation of the degraded southern chernozems and dark chestnut soils structure during 13 and 7 years of direct sowing, respectively, has not been established. It takes much longer to rehabilitation the aggregate state of soils, which is currently in a critical condition of the content of aggregates> 10 mm in size and the sum of agronomically valuable aggregates. The soils under 60-year treeline, as a control, showed a satisfactory range of aggregates, which indicates a high degree of soil degradation in the past and a long period of their recovery time. The effectiveness of direct sowing usage in the cultivation of a wider range of grain and row crops (winter wheat, sunflower, peas, chickpeas, rapeseed, buckwheat, corn) is due to the peculiarities of agricultural technologies. Abandoning of naked fallows and soil treatments with the simultaneous use of plant residues and cover crops on the soil surface between the harvest and sowing of winter crops provides an anti-erosion effect and, as a consequence, a decrease in physical evaporation, an increase in moisture and biota reserves, an increase in microbiological processes, which are noted in the form trends in improving the agrochemical and agrophysical properties of soils.