Article Info Received : 13.05.2016 Accepted : 02.08.2016 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, MesicXeric, 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 present study describes signature lipid biomarkers in reclaimed mine soils, 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 reclaimed mine soils was bimodal with maxima at C 18 and C 29 \C 31 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 reclaimed mine soils 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.

Article InfoThe 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 paper deals with Botegrad valley soil cover, properties, conditions and vegetation. The soil cover in the Botevgrad region is characterized by considerable diversity in the ravine valleys of the Bebresh River and its tributaries. Alluvial and Diluvial soils occur in the middle of the region in lowest parts. Gray forest soils developed in the Pre-Balkans and the northern slopes of the Balkan Mountains and Light Gray forest soils (Pseudopozolic soils) are spread there too. The most fertile soils are Dark gray forest soils but only in limited area. Shallow soils (Lithosols), are widely spread over reddish-brown quaternary materials, characterized by the presence of many skeletal particles. The soil cover on the slopes is eroded, cut by deep ditches, ravines and valleys. Main part of the land in the valley is cultivated. Arable lands for cultivation and pastures are about 68.4%, other 22% are used for mainly for forestry. Settlements, industrial zones and other infrastructure occupy 9% of the valley.

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