The paper summarises contemporary research on soils that have been formed under natural conditions or have been influenced by anthropogenic activity. The need to periodically obtain new data to prepare an up-to-date soil assessment was highlighted. Brief information is presented about the district in which the studies were conducted and the distribution of the different soils. The discussion of selected scientific publications is enriched with graphical representation of location of the soil profiles, studied by the authors, or the Municipalities in the selected areas of which the soil studies were carried out. For some studies, additional calculations were made regarding the clay and humus content of soils. The conducted scientific summary found that the discussed studies confirm the influence of the specific conditions of soil formation on various soil features, related to natural processes, creation of unfavourable soil conditions, morphological changes in the soil profile or alteration in ecological state of the soils.
During the period 2020-2024, a study was conducted on the technological characteristics of the white wine grape variety Kristalen. The research was carried out at the Institute of Agriculture and Seed Science “Obraztsov Chiflik” – Rousse and the Institute of Viticulture and Enology – Pleven and covered 5 consecutive harvests. The changes in the climatic factors in the growing region were monitored each year as well as their influence on grape quality. The grapes were processed using the classical technology for white wine production under microvinification conditions. The chemical composition of the grapes was determined for each vintage as well as that of the experimental wines made. The grapes from the 2024 harvest had the best indicators, which showed the highest sugar accumulation, titratable acids content and glucoacidimetric indicator. The 2023 harvest had the lowest values of the studied components. No general trend was established regarding the analysed chemical indicators in the composition of the experimental white wines. The highest alcohol content was found in the 2021 vintage, while the highest levels of residual sugars and phenols were determined in 2023, of total and sugar-free extract - in 2024, and of titratable acids - in 2022. An organoleptic analysis was also performed of the experimental wines. The wine with the best sensory profile in terms of colour, aroma, and taste was the 2022 vintage, which was evaluated as the most harmonious and well-balanced.
Understanding how soil slope positions influence soil hydraulic and physical properties is crucial for sustainable land and water management, particularly in regions vulnerable to erosion and water scarcity. This study evaluated the effects of slope position on soil hydraulic and physical properties in northeastern Nigeria. Nine soil profile pits were made along an upper–middle–lower slope sequence, and soil samples were collected and analyzed for particle size distribution, bulk density (BD), total porosity (TP), saturated hydraulic conductivity (Ksat) and plant-available water content (AWC). Results showed that sand dominated across slope positions, with values decreasing with soil depth, while silt and clay increased downslope. BD values ranged from 1.36 -1.75 g cm⁻³, indicating moderate compaction. Soil TP (32-47%) generally increased with soil depth and was inversely related to BD. Mean Ksat ranged from 2.14 cm/hr (middle slope) to 3.09 cm/hr (upper slope), decreasing consistently with depth. Available water content varied between 0.29 and 0.37 cm³ cm⁻³, increasing with decreasing slope position. These variations suggest that upper slopes favor rapid infiltration and drainage but risk moisture deficits, while middle and lower slopes retain more water but are prone to waterlogging and reduced aeration. The findings highlight the strong topographic control on soil hydrological behavior, emphasizing the need for slope-specific management practices such as organic matter amendment on upper slopes and improved drainage on lower slopes to optimize soil moisture and prevent land degradation.
The present study evaluates the impact of organic fertilization on the biometric and productive indicators of the ‘Polka‘ raspberry cultivar under the influence of combined abiotic stress – transplant shock, drought, and extreme high temperatures (2025). The experiment was conducted at the experimental field of the Faculty of Agriculture at Trakia University, using a planting scheme of 2.20 x 0.30 m. The main objective of the research is to determine the potential of organic fertilization to mitigate the negative effects of stress and maintain the productivity of the plantation. Vegetative parameters (number, height, and diameter of shoots) and reproductive indicators (yield and fruit weight) were analyzed. The results show that the extreme conditions in 2025 severely suppressed vegetative growth in the control (unfertilized) plants, where shoot height and thickness decreased by 50.4% and 47.6%, respectively, compared to the previous year. Organic fertilization exhibited a pronounced buffering effect, maintaining a better vegetative habitus and an optimized shoot density (14.3 shoots/m). This led to a 37.16% higher yield in the fertilized variants (1154.9 g/m) and preserved the standard fruit size under drought conditions. The study proves that organic fertilization is a key factor for enhancing resilience and maintaining raspberry productivity under abiotic stress.
Grain yield formation in winter wheat is a complex process governed by the interaction of multiple yield components, whose relative contributions are difficult to quantify under multi-environment conditions due to strong interdependencies among traits. The present study aimed to identify the key determinants of grain yield and to clarify their relationships using an integrative analytical framework. A dataset comprising 36 winter wheat genotypes across four experimental locations in Bulgaria over four growing seasons was analyzed. Correlation analysis, linear mixed modelling, Random Forest, and Partial Least Squares regression were applied to assess trait contributions and address multicollinearity. Across all approaches, the number of grains per square meter consistently emerged as the dominant determinant of grain yield, showing the strongest association (r=0.92), the highest standardized effect (β=1.330), and the greatest importance in the Random Forest model (0.896). In contrast, the number of productive tillers and the number of grains per spike showed strong pairwise associations with yield but negligible or negative effects in multivariate and non-linear models, indicating predominantly indirect contributions mediated through grain number per unit area. Thousand grain weight exhibited a partially independent contribution, supported by its importance in the Random Forest model (0.090) and its strong loading on the second latent component in the Partial Least Squares analysis (0.956). These results indicate that grain yield formation is governed by a hierarchical structure dominated by grain number, while grain weight plays a complementary role. The integration of multiple analytical approaches provides a robust framework for understanding trait interactions and supports targeted trait prioritization in wheat breeding under variable environmental conditions.
