Fertile Chernozems of Southern Russia are of great value, so it is important to study the impact of agricultural activities on the soil quality. Changes in taxonomic composition and α-diversity of microbial communities of agricultural soils occupied by pea (Pisum sativum L.) and chickpea (Cicer arietinum L.) in response of cropland management were studied. A field experiment was conducted under four different conditions: (1) control, (2) mineral fertilizers (NPK) application alone, (3) pesticides application alone, and (4) fertilization combined with pesticides. The taxonomic composition of the soil bacterial community was studied by amplification and sequencing of the 16S rRNA gene. The predominance of Actinobacteria (17.7–32.3%), Proteobacteria (17.7–28.2%), Planctomycetes (10.1–21.3%), Acidobacteria (5.3–11.1%), Chloroflexi (1.0–7.1%), Gemmatimonadetes (2.5–8.0%), Bacteroidetes (3.6–11.3%), and Verrucomicrobia (3.9–9.2%) was noted. Introduction of pesticides led to an increase in the relative abundance of Chlorobi and Gemmatimonadetes. The time of sampling was the main significant factor determining the differences in the structure of soil microbial communities. All treatments did not have a significant effect on the α-diversity of the studied soils. Thus, treatment with mineral fertilizers and pesticides does not have a significant negative effect on the bacterial community of cultivated soils.

Soils are a hotspot for the emergence and spread of antibiotic resistance. The effects of agrochemical treatments on the bacterial community of agricultural soils and the content of antibiotic-resistance genes (ARGs) were studied. Treatments included the following: control, mineral fertilizers (NPKs), pesticides, and the combined treatment of soils under soya (Glycine max), sunflower (Helianthus annuus L.), and wheat (Triticum aestivum). Bacterial community taxonomic composition was studied using 16S rRNA gene sequencing. The content of 10 ARGs and 3 integron genes (intI1, intI2, intI3) was determined using quantitative real-time PCR. The results showed that the treatments had little effect on the taxonomic composition and diversity of the soil bacterial community. The most significant factors determining differences in the microbial community were sampling time and soil physico-chemical parameters. A significant role of the bacterial community in ARG distribution in soils was demonstrated. Representatives of the Pseudomonas, Bacillus, Sphingomonas, Arthrobacter genera, and the Nocardioidaceae and Micrococcaceae families were likely ARG hosts. The presence of integron genes of all three classes was detected, the most numerous being intI3. This work provides important information on the role of agricultural soils in ARG transfer, and the findings may be useful for sustainable and safe agricultural development.

Pesticides and fertilizers used in agriculture can negatively affect the soil, increasing its toxicity. In this work, a battery of whole-cell bacterial lux-biosensors based on the E. coli MG1655 strain with various inducible promoters, as well as the natural luminous Vibrio aquamarinus VKPM B-11245 strain, were used to assess the effects of agrochemical soil treatments. The advantages of using biosensors are sensitivity, specificity, low cost of analysis, and the ability to assess the total effect of toxicants on a living cell and the type of their toxic effect. Using the V. aquamarinus VKPM B-11245 strain, the synergistic effect of combined soil treatment with pesticides and mineral fertilizers was shown, which led to an increase in the overall (integral) toxicity of soils higher than that of the individual application of substances. Several probable implementation mechanisms of agrochemical toxic effects have been discovered. DNA damage caused by both SOS response induction and alkylation, oxidative stress due to increased superoxide levels, and damage to cellular proteins and membranes are among them. Thus, the usage of biosensors makes it possible to assess the cumulative effect of various toxicants on living organisms without using expensive chemical analyses.

The article presents the results of a 3-year experiment to study the soil structure with the combined use of insecticides and a humic preparation. Crops were peas (Pisum sativum) and chickpeas (Cicer arietinum). The experiment was carried out in 2019–2021 at the experimental fields of the Federal Rostov Agrarian Scientific Center, located in the Rostov region in the south of the European part of Russia (47°21′ N, 39°52′ E). Soil was Calcic Chernozem Loamic. The studies were carried out both without fertilization and with the use of mineral fertilizers (N40P40K40). Sowings of leguminous crops were treated with a mixture of insecticides and a humic preparation in the phase of bean formation. The humic preparation BIO-Don10 was obtained according to the authors’ technology by alkaline extraction from vermicompost—a product of manure processing by compost worms of the Eisenia foetida species. The preparation contains salts of humic acids and fulvic acids in the amount of 1.9 g/L; the concentration in the mixture with the insecticide was 0.002%. An increase in the structure and water resistance coefficients was observed. A decrease in the block fraction and an increase in the total number of agronomically valuable aggregates were substantiated. It was found that in the cultivation of legumes, the application of mineral fertilizers had a negative effect on the structure of the soil, while, when using pesticides, the structure was preserved better by the end of the growing season. The revealed patterns can be associated with the activity of microorganisms participating in the hydrolysis of organic compounds that stabilize soil aggregates.

The article presents the results of a field experiment to study the effect of biological preparations on the dynamics of mobile forms of nitrogen in 2021-2023. The tests were carried out in the conditions of the Rostov region, on ordinary carbonate chernozems. The experimental design included bacterial (Planriz, Geostim) and humic (BIO-Don 10, potassium humate) preparations, as well as different nutrition levels (without fertilizers and azofoska 250 kg/ha). Mineral nitrogen is characterized by high mobility; data on hydrothermal conditions and the dynamics of ammonium and nitrate nitrogen by year and nutrition level are presented. It has been established that the use of humic preparations stimulates plant nutrition, which is expressed in negative dynamics compared to the control; this effect is enhanced by the combined use of bacterial and humic preparations. As a result, the yield increased to 28.0% compared to the control and up to 24.9% compared to the background.