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Purpose: to develop rational combinations of species and varieties of perennial leguminous grasses, soil water and nutrient regimes, which will contribute to obtaining stable fodder yields with high levels of protein and energy content. Materials and methods. Research is being carried out on perennial leguminous grasses on the experimental field of the institute. The experiment is three-factor and includes three options for maintaining the pre-irrigation soil moisture limit (60, 70 and 80 % of the lowest moisture capacity), three options for the soil nutritional regime (NPK₁, NPK₂ and control – without fertilizers), eight types of legumes are studied according to the third factor. The generally accepted experimental methods were used when setting up experiments and conducting research. Results. In the full germination phase there were from 294 to 386 plants of grass species per 1 sq. m. Their height before harvesting varied according to the experimental variants from 0.60 to 1.01 m in the first cutting, from 0.38 to 0.94 m in the second and from 0.25 to 0.66 m in the third cutting. The grass stand total water consumption in the year of seeding was 4.2–4.7 thous. cub. m/ha, increasing in subsequent years to 4.8–5.7 thous. cub. m/ha. The soil water regime and fertilizers had a significant impact on crop yield. In control options with a pre-irrigation limit of 60 % of the lowest moisture capacity, the green mass yield in the second year was 26.6–40.9 t/ha. With improved soil nutrition and good water supply, the yield increased to 48.2–87.8 t/ha. Sainfoin and blue-hybrid and variegated alfalfa plants responded to the improved growing conditions most actively; 54–88 t/ha of green mass were gathered from these sites during the season. Conclusions. Selection of optimal combinations of soil water and nutrient regimes, as well as the new promising perennial leguminous grasses species and varieties introduction into the field feed production in the Lower Volga region will ensure high and stable yields of fodder rich in energy and nutrients.

Purpose: scientific substantiation of the use of agro-reclamation tillage practices of light chestnut heavy loamy soils in rice cultivation with periodic irrigation by sprinkling. Materials and methods. The research was conducted at the experimental site of the All-Russian Research Institute of Irrigated Agriculture in 2022–2023 with Stalingrad 1 rice crops in a two-factor experiment: factor A (soil water regime) – two options and factor B (tillage) – three options. Generally accepted methods of laying and conducting field research were used. Results. Immediately after rice sowing, the soil density in the layer of 0.0–0.6 m, varied in the range of 1.19–1.41 t/cubic m depending on the tillage practice. The minimum value of soil density in the layer of 0.0–0.6 m was formed in the A2B3 variant and amounted to 1.23 t/cubic m. The maximum soil compaction in this layer of 1.34 t/cubic m was observed in variant A1B1. During the period of full ripeness of the grain, soil compaction occurred in all tillage options. Its minimum compaction (1.34 t/cubic m), compared with the control (winter plowing), was noted with a combination of winter plowing and spring deep loosening. The minimum values of the water consumption coefficient and irrigation water loss were obtained in the A2B3 variant, and their numerical values were 851.7 and 703.6 cubic m/t, respectively. Conclusions. It was found that winter plowing to a depth of 0.25–0.27 m in combination with spring deep loosening to a depth of 0.40 m, in comparison with traditional winter plowing in one step, provides a decrease in soil density in a layer of 0.0–0.4 m by 0.10 (after sowing) and 0.12 t/cubic m (during the period of full ripeness of grain), which contributes to the yield increase to 6.95 t/ha and a reduction in irrigation water loss by 112.4 cubic m for the formation of 1 ton of grain.

Purpose: to study the features of irrigation regimes and their impact on the yield of sweet pepper based on the analysis of scientific sources of information. Discussion. Sweet pepper is a moisture-loving crop. For its normal growth and development, optimal soil moisture is required. Plants experience a special need for moisture when planting seedlings, flowering, as well as during fruit set and formation. Since sweet pepper crops are located in southern regions with a moisture deficit, irrigation acts as a guarantor of obtaining the planned yield of this crop. The main elements of the irrigation regime are irrigation, irrigation norms, the number of irrigations, the timing of their implementation to maintain a given level of soil moisture during crop cultivation. Modern irrigation regimes for sweet pepper have been developed both for conditions of full provision of water resources and for conditions of their deficiency. Under conditions of full water supply, maximum productivity and product quality indicators, more efficient use of irrigation water are ensured by drip irrigation mode with maintaining the pre-irrigation moisture threshold of the calculated soil layer at least 70–80 % of the lowest moisture capacity during the growing season. In differentiated irrigation regimes, higher values of pre-irrigation soil moisture thresholds are maintained in the first half of the growing season, when it is necessary to create favorable conditions for the rooting of seedlings, growth and development of plants. However, during this period the size of the calculated soil layer is reduced. By the stage of technical ripeness and until the end of fruit harvesting, soil moisture thresholds are reduced to 70–75 % of the lowest moisture capacity, but the moistened layer is increased. Conclusions. Optimal irrigation regimes make it possible to maintain the vital processes of plants and obtain the planned productivity even in dry conditions. The combination of irrigation modes with other elements of the technological process (mulching, fertilizing, etc.) increases the productivity of sweet pepper by 15–20 %.

Purpose: to determine and scientifically substantiate the optimal combinations of regimes for regulating soil moisture by irrigation and the use of biological plant protecting agents at various stages of their growth and development, ensuring the minimization of anthropogenic impact on the environment. Materials and methods. The studies were conducted in 2021–2022 on the experimental site of the All-Russian Research Institute of Irrigated Agriculture near the village Vodny, Sovetsky district of Volgograd, in plantings of the Gulliver potato variety in a two-factor field experiment. Factor A: A₁ – the moisture content of the soil layer 0.4 m deep throughout the entire potato growing season was maintained at a level not lower than 70 % of the minimum moisture capacity; A₂ – the same, only at 80 % of the minimum moisture capacity. Factor B: B₁ – biological system of potato plant protection; B₂ – integrated protection system; B₃ – chemical protection system (control). The experiment was carried out on light chestnut, heavy loamy, low-humic, non-saline soils. In terms of precipitation, the years of research are characterized as: 2021 – average wet, 2022 – average. Results. In the first option of the irrigation regime, the irrigation rate of 2720 and 3060 cubic m/ha was provided with eight and nine irrigations. The second irrigation regime was maintained with almost twice as many irrigations – up to 15–17, but at the same time the watering rate decreased to 230 cubic m/ha, and the irrigation rate increased to 3450–3910 cubic m/ha. In the option of the moisture regime of 80 % of the minimum moisture capacity in a horizon of 0.4 m, in conjunction with a plant protection system based on the use of biological preparations, the largest green matter of 385 g/plant, which is 98 g/plant more control one was obtained. The maximum mass of tubers in the nest was also obtained in this combinable option; it was 660 g/plant, which is 30 % higher than the option with chemical protection. Conclusions: on low-fertility light chestnut soils of the Lower Volga region, potatoes are best cultivated at a moisture regime in which humidity does not fall below 80 % of the minimum moisture capacity in a soil horizon of 0.4 m, in conjunction with a plant protection system based on the use of biological preparations, which provides favorable conditions for obtaining a tuber yield of 32.4 t/ha.

Longer term monitoring of soil water content at a catchment scale is a key to understanding its dynamics, which can assist stakeholders in decision making processes, such as land use change or irrigation programs. Soil water monitoring in agriculturally dominated catchments can help in developing soil water retention measurements, for assessment of land use change, or adaptation of specific land management systems to climate change. The present study was carried out in the Pannonian region (Upper-Balaton, Hungary) on Cambisols and Calcisols between 2015 and 2021. Soil water content (SWC) dynamics were investigated under different land use types (vineyard, grassland, and forest) at three depths (15, 40, and 70 cm). The meteorological data show a continuous decrease in cumulative precipitation over time during the study with an average of 26% decrease observed between 2016 and 2020, while average air temperatures were similar for all the studied years. Corresponding to the lower precipitation amounts, a clear decrease in the average SWC was observed at all the land use sites, with 13.4%, 37.7%, and 29.3% lower average SWC for the grassland, forest, and vineyard sites, respectively, from 2016 to 2020 (measured at the 15 cm depth of the soil). Significant differences in SWC were observed between the annual and seasonal numbers within a given land use (p < 0.05). The lowest average SWC was observed at the grassland (11.7%) and the highest at the vineyard (28.3%). The data showed an increasing average soil temperature, with an average 6.3% higher value in 2020 compared to 2016. The grassland showed the highest (11.3 °C) and the forest soil the lowest (9.7 °C) average soil temperatures during the monitoring period. The grassland had the highest number of days with the SWC below the wilting point, while the forest had the highest number of days with the SWC optimal for the plants.

The aim of this study was to assess the impact of different vegetation on the distribution of rainfall (due to throughfall and stemflow), water regime, and Al and SO4 2- leaching from forest soils. The water flow and Al and SO4 2- transport were modeled using HYDRUS-1D. The study was performed at two elevation transects on the Paličník and Smědava Mountain in Jizera mountains. Podzols and Cambisols were prevailing soil units in this area. It was shown that the effect of the precipitation redistribution on water regime was considerable in the beech forest, while it was almost negligible in the spruce forest. Redistribution of precipitation under trees caused runoff (in one case), increased water discharge through the soil profile bottom, reduction of water storage in the soil, and thus reduction of root water uptake. Simulated Al leaching from the soil profile was determined mainly by the initial Al content in the soil profile bottom. Leaching of SO4 2- was mainly determined by its initial content in the soil and to a lesser extent by redistributed precipitation and SO4 2- deposition.