The present study describes signature lipid biomarkers in reclaimed mine soils (RMSs), an unreclaimed spoil and a natural soil (Vertisol) for a major coal mine basin in Eastern Europe. Alkanes, fatty acids and fatty alcohols, as well as coal biomarkers were abundant in the mine soils and the unreclaimed spoil. The alkanes distribution in the RMSs was bimodal with maxima at C₁₈ and C₂₉/C₃₁ and points at two origins for the alkanes, terrigenous plants, including soil borne and from the coal source. Fatty acid carbon preference indices (CPI_even/odd = 10.4 and 8.1 for the mine soils under pine and grass vegetation) reflect the increasing role of terrestrial vegetation in the formation of organic matter. The higher concentrations of the long-chain alkanes, fatty acids and alcohols are speculated as the reason for the severe and extreme water repellency observed with the Vertisol and the unreclaimed spoil. The presence of terrigenous steroid and triterpenoid markers in the RMSs is an indication of the ongoing soil formation processes. The analysis of lipid extracts allowed for the assessment of sensitive molecular indicators of biogenic terrigenous and coal origin and the degree of soil recovery following >20 years of spoils reclamation.

The present paper focused on content, quality and composition of soil organic matter in different pedoclimatic zones of Bulgaria. The country has temperate continental climate with Mediterranean influence. There are six combinations of soil temperature and moisture regimes over the territory of Bulgaria, such as Thermic-Xeric, Mesic-Xeric, Mesic-Ustic, Mesic-Udic, Cryic-Udic and Pergelic – Udic. Typical soil types for Bulgaria are Chernozems, Luvisols. Vertisols, Cambisols, Phaeozems, Leptosols, Regosols, Planosols, Umbrisols and etc. Fifteen soil profiles were studied which are representative for the area. The content and composition of organic matter were determined according to the method of Kononova-Belchikova. The purpose of this study is to determine the influence of pedoclimatic conditions over soil organic matter content and composition of various areas with different soil cover, vegetation, management and etc. Grouping soil types in different soil temperature and moisture regimes shows that there are similarities in soil carbon content and composition. Soils developed under cooler and moister conditions accumulate more organic carbon. In such areas the content of organic carbon can reach about 255 t.ha-1 in a surface horizon and the type of humus is predominantly Fulvic. Respectively, soils developed under dry and warmer conditions have lower organic carbon content and the type of humus is usually Humic.

The paper deals with of the relations between the forest ecosystem, calcareous rocks and content and composition of soil organic matter in the Golo Bardo area in West Bulgaria. In that area Rendzinas are used mainly for forestry, viticulture and pastures. A specific study based on the accumulation of soil organic matter according to the data on the composition of the soil organic acids. The research on the soil organic matter composition provided information on the course of the humification processes in studied soils. Soil organic matter accumulation in Rendzinas depends on different factors, such as land use and climatic conditions. Soil has rapid transformations of organic residues and strongly decomposed plant tissue predominates. There are often signs of active work of the soil mesofauna. Studied soils have good reserves of organic carbon high degree of humification. The organic carbon content varies in a wide range from 0.8 to 7.2 %. The humic acids prevail over fulvic acids, and the degree of humification is higher in deeper horizons. According to the C/N ratio the humus type is Mull in almost all horizons. Studied soils are biologically active that have favorable impact over the soil structure and vegetation. Rendzinas have high potential of organic carbon sequestration.

The aim of the present study is a spatial analysis and assessment of the main physicochemical properties of the soils in Botevgrad Valley. The soil samples were taken along a pre-selected grid to cover the areas selected for research as uniformly as possible. The data were interpolated using the geostatistical methods of kriging and variogram analysis. The soils have relatively favourable physicochemical properties, such as the cation sorption capacity with values from 10.80 to 24.50 mequ/100 g of soil. The basic cations, such as calcium and magnesium, dominate anywhere, and those with acidic functions, such as exchangeable aluminium and hydrogen, have minimal values. The base saturation is almost above 50%, and the soils are defined as Eutric. Soil reaction also varies from strongly acidic to slightly alkaline.

The paper deals with spatial analysis that evaluates the main agrochemical properties of the Botevgrad valley. The soil samples were taken along a pre-selected grid so as to cover the areas selected for research. The interpolation of the data was done according to geostatistical interpolation method and the output value is using Inverse Distance Weighting (IDW). Spatial distribution is a valuable tool for determining nutrient availability and nutrient management practices to optimize crop production and minimizing environmental impacts. As a general guideline, total nitrogen content in soil is commonly found in the range of 0.1% to 0.2% on a weight basis. Soils with higher organic matter content often have higher total nitrogen levels because organic matter is a significant source of nitrogen. It’s important to note that the optimal levels of available potassium and phosphorus can vary depending on the specific soil type.