The Impact of Pre-Crops on the Formation of Water Balance in Winter Wheat Agrocenosis and Soil Moisture in the Steppe Zone

Under climate change, the issue of selection and correction of crop cultivation systems in the zone of moisture deficit and risky farming to ensure profitability of production is still topical. In particular, crop rotations are a practice aimed at increasing resistance of soil systems to abiotic and biotic stresses in the zone of moisture deficit. Therefore, the purpose of the research is to identify spatio-temporal regularities of vegetative formation of water balance in winter wheat agrocenoses depending on a pre-crop according to the unified BBCH scale. Spatio-temporal processes of vegetation and water balance formation in winter wheat agrocenosis depending on a pre-crop according to the unified BBCH scale were examined on the basis of the data of decoded satellite image series of the spacecraft Sentinel and calculation of the NDWI and the NDVI values. The research was conducted in the natural-climatic conditions of the Steppe zone of Ukraine, in the territory of Yelanets district, Mykolaiv region, during the vegetative phase of winter wheat variety Driada 1: autumn 2021 and winter, spring and the beginning of summer 2022. It was established that activeness of water balance formation in winter wheat agrocenosis with pea as a pre-crop according to seasonal-phenological stages of plant growth is 3.0-9.0 times higher than with a grain crop (spring barley) and sunflower as pre-crops. In particular, with pea as a pre-crop, the NDVI vegetation of winter wheat plants is 1.6-1.7 times more intensive, the rate of moisture supply NDWI in the plant leaf at the macro-stages BBCH 10-61 is 1.54 and 1.82 times higher, productivity is 1.43-1.56 times higher. We observed a 30.5-34.3% reduction in water consumption for the formation of a ton of winter wheat grain with pea as a pre-crop in comparison with other pre-crops that resulted in an increase in productive moisture reserves at the end of vegetation in a meter soil layer by 20%. It was established that using pea as a pre-crop has economic and environmental benefits that manifest themselves in increasing resistance of soil systems, a reduction in environmental pollution and a rise in profitability of production

Spatial Modeling of the Effects of Deflation Destruction of the Steppe Soils of Ukraine

The decrease in the agricultural efficiency is associated with the influence of wind erosion, the consequence of which is a decrease in the soil fertility. Significant effects of wind erosion are typical of the arid and semi arid zones with a small amount of precipitation, high air temperature and degree of evaporation, reinforced by strong winds and low differentiation of plant protection. It has been proven that the intensity of the effects of deflation processes depends on the physical and geographical conditions of the distribution of agricultural land, systematic soil protection activities and the availability of vegetation. It has been established that the acceleration of the deflation processes occurs in the territories with increased anthropogenic pressure, which leads to ecological disturbance of the natural balance characterizing territorial ecosystems. In the course of the studies it was found that the natural processes of wind erosion are significantly enhanced by the absence of a scientifically-based and ecological land development system of agriculture, which leads to destruction of the soil cover, reduction of soil fertility, damage to the agricultural crops and, thus, the economic damage. As a result of application of the GIS and ERS technologies, the empirical-statistical model of the possible soil loss due to wind erosion in the territory of the Steppe zone of Ukraine, it has been found that in the course of the deflation processes in the territory taken by naked fallow upon the absence of the conditions for the deflation resistance activities, the value of soil loss at the epicenter of dust storms can reach about 600 t / ha. Studies proved the importance of the deflation resistant action of the vegetation cover, which tends to an increase in the erosion dangerous (favorable) areas of agricultural land by 1.7 times, which reduces the soil loss by 5.62 times. In accordance with the intensity of the effects of the deflation processes and the increase of the soil losses, the contour and land development deflation resistance activities with elements of soil protection agriculture were proposed

Anthropogenic and Climatic Causality of Changes in the Hydrological Regime of the Dnieper River

The intensive use of water resources and the transformation of natural landscapes under the influence of human economic activity have led to changes in the natural water balance of river drainage basins. The negative processes thereof are intensified by climatic changes that have significantly disturbed the hydrological regime, determined by changes in water content and river flow dynamics. The retrospective study and prediction of the flow of the Dnieper River was carried out using multivariate statistics and adaptive methods of nonlinear time series analysis. The anomalous features were identified and the main periods of changes in the water regime of the river for 190 years (1818–2008) were determined using the standard root-mean-square deviation and wavelet analysis. As a result of non-linear prediction, it was determined that if the tendency of anthropogenic and climatic formation of the water regime of the Dnieper River sustains, there is a 90% probability of insignificant but steady trend and cyclical reduction of the average annual flow by 1.6 m3/s per year to 1120 ± 270 m3/s by 2040. The results of the detailed retrospective analysis for 190 years and the prediction of the probability of changes in the flow of the Dnieper river confirm the previous conclusions of many scientists regarding the significant transformation of the ecosystem of the transboundary river and provide new knowledge regarding the main stages of formation of the water regime and the probability of further regulation of the flow of the Dnieper river if the current conditions of the negative impact of economic activities are maintained in the transboundary basin

Geomodelling of Destruction of Soils of Ukrainian Steppe Due to Water Erosion

Spatial raster distribution models of the values of factors influencing the potential soil erosion hazard were created using GIS technologies. The erosion hazard was estimated using the modified RUSLE (Revised Universal Soil Loss Equation) model. The potential of annual soil loss of arable land was calculated. The spatial gradation of erosion violation of administrative and territorial units in the steppe zone of Ukraine was provided. About 32.7% of arable land that is subject to high erosion hazard was allocated. About 48 administrative and territorial units have a specific area less than 5% of erosion disturbed lands. They are characterized by a resistant type of agrolandscapes regarding the water-erosion processes. Most administrative and territorial units with high erosive-accumulative potential (the percentage of the area is 15% or more) are located in the western and southwestern parts of the steppe zone of Ukraine. The specific area of erosion hazardous lands reaches up to 32% in separate administrative-territorial units. The obtained results allow determining the need for a spatially discrete-distribution implementation of adaptive-landscape anti-erosion design with the elements of soil-protective agriculture