The Soils of Serbia

Pedological research in Serbia began in the middle of nineteenth century in the Principality of Serbia and continued in the Kingdom of Yugoslavia, the Socialist Federal Republic of Yugoslavia (SFRY), and the Republic of Serbia. From 1960 to 1985, detailed research was undertaken in different soil types and on improving their classification. The Classification of Yugoslav Soils (Škorić et al., 1985) is the official soil classification which is used today in the Republic of Serbia.

The soil cover of Serbia is not high in terms of surface area, but it is significant due to the large number of systematic units which originated as a consequence of the diversity of the conditions for the formation and pedogenesis of certain soil types. The soils of Serbia are extremely heterogeneous as a result of the varied geological substrates, climate, vegetation, soil flora and fauna. Soils are divided into eight fertility classes, reflecting their relative suitability for agricultural production, with classes 1–4 representing higher quality soils. However, about 45% of the total land area belongs to soil classes 4–8, which are not suitable for tillage and profitable crop production, and this land is used for semi subsistence vegetable or fruit production or as meadows. 

A mild temperate (mesothermal) climate (i.e. Köppen’s ‘C climate’) dominates in Serbia. However, on high mountains (i.e. at altitudes above 1,500 m), the climate is ‘boreal’ or microthermal (i.e. Köppen’s ‘D climate’), while the Tundra climate (Köppen’s ‘ET climate’) is only sporadically represented, occurring in regions above 2,000 m. The Dinaric Mountains form a topographic barrier that affects the precipitation pattern of the Balkan Peninsula with the west-facing side of the Dinarides receiving large amounts of rainfall. A semi arid season lasting from July to October is characteristic for the Pannonian region, while in eastern lowland regions (the Danube and Timok river valleys), seasonal drought is more severe, with the dry period lasting from July to September. 

Zonal vegetation in Serbia reflects regional climatic conditions. The lowland zone, with a (semi-)arid climate, is covered either by steppe fragments, steppe forests, or riparian forests along large rivers. Colline (hilly) and low-mountain regions (at an altitude of between 300 and 500 m) are more humid, but also very dry, especially in eastern Serbia. This climate zone is covered by xeric oak forests. Mesic beech forests cover mountain regions (between 500 and 1,000 m a.s.l.), which are characterized by humid periods during each season. Coniferous forests dominate in the altimontane habitats (between 1,000 and 1,500 m) with a microthermal boreal climate. Finally, herbaceous vegetation dominates within the (sub)alpine zone with a tundra climate. Azonal vegetation is determined primarily by specific soil and hydrological conditions (waterlogged habitats, halomorphic soils, sand dunes, etc.).

The territory of the Republic of Serbia comprises various geological units of composite structures and complex composition. Precambrian and Palaeozoic metamorphic rocks form the basement overlaid by marine Mesozoic sediment formations and Ophiolite melange. They are further overlaid by sediments of the Pannonian Sea and Neogene lakes, which are then covered by unconsolidated Quaternary deposits of various geomorphological origins. They are also intruded by various igneous rocks and volcanic tephra, rich in pyroclastics. The lithological map comprises 28 mapping units of the parent material types with an approximately equal proportion of hard and soft unconsolidated rocks. The mineralogical composition of the soils comprises quartz, mica, feldspars, calcite, dolomite, and chlorite. In the clay fraction, illite, smectites, and kaolinite are found in association with chlorite, vermiculite and mixed-layer-silicates. The temperate climate and low precipitation are advantageous for the biogeochemical weathering of primary minerals to clay minerals: illite, smectite, and vermiculite during bisiallitisation processes.

The Classification of Yugoslav Soils (Škorić et al., 1985) is the official soil classification which is used today in the Republic of Serbia. It has six categories of taxons (orders, classes, types, subtypes, varieties, and forms) connected hierarchically and based on logical principles. According to this Classification, soils in Serbia are divided into four orders depending on the character of soil wetting and the composition of the water which wets the soil: 1) Automorphic soils; 2) Hydromorphic soils; 3) Halomorphic soils; and 4) Subaqueous (subhydric) soils.

Automorphic soils are characterized by wetting through precipitation only with no additional wetting. Water percolates through the soil profile freely without any prolonged retention on the impermeable horizon. These soils predominate in Serbia, covering approximately 66,323.58 km² or 74.9% of the land area and this order is divided into six classes according to the degree of profile development.

Soils of this order are characterized by temporary or permanent excessive wetting in part of or through the entirety of the profile. The genesis and properties of hydromorphic soils mainly depend on the hydrologic regime which includes: sources of water and the manner of excessive wetting; the zone in the profile affected by this wetting; and the duration of the excessive wetting. Soils of this order cover approximately 20,897.15 km² or 23.7% of the land mass of Serbia. 

Halomorphic soils cover approximately 1,140.29 km² or 1.3% of the land mass of Serbia and this order is divided into two classes. Subaquatic soils occupy very small areas and have no economic significance. Only when dried out they can be used for plant cultivation, at which point these soils, in the new conditions, change drastically and lose their previous characteristics.

Every year a proportion of the agricultural land in Serbia undergoes a change in use. In the second half of the twentieth century, Serbia lost approximately 220,000 ha of agricultural land irrecoverably to the construction of industrial, mining, energy, and traffic infrastructure. Projections based on existing data on the annual reduction in the amount of fertile land suggest that the loss on this basis could amount to as much as 180,000 ha over the next 30 years. 

A significant proportion of the land area of the Republic of Serbia occupied by the areas prone to erosion, landslides, surface exploitation of mineral resources, and dump sites can be classified as degraded. The basic natural processes of soil degradation are water and wind erosion; the loss of organic material, compaction due to an increase in volumetric weight and a decrease in soil porosity; salinization through the accumulation of soluble salts in soil; landslides, i.e., the moderately fast or fast movement of a mass of soil and rock down slopes, etc. However, various human activities connected to the exploitation of natural resources from the land result in its immediate loss as well as pollution, such as mineral extraction activities, industry, borrow pits for industrial requirements, and the exploitation of gravel and sand at the edge of rivers.