About the transformation and degradation mineral component Estonian soil in pedogenesis.
The general direction of the development of soils is determined mainly by the natural factors and their mutation. The precipitation level in Estonia (752 mm) surpasses the level of evaporation (462 mm), the average temperature is 5.0 °C.
The peculiarity of the Estonian soil’s parent rock is that the amount of carbonate stone and their decomposition product in them differs greatly (0…100%). The same goes for the parts of clay.
The age of the soils is very different. In South-East Estonian Uplands 10…13 thousand years, in Coastal regions less than 1 thousand years.
In the transformation of the mineral parts of the soil the leading part is played by car-bonate leaching, lessivage, podzolization and gleying. The changes caused by them can be seen in the morphological profile of the soil, in the vertical differentiation of the soil’s granulometrical and chemical composition (Table 6).
In the stage of carbonate leaching, the amount of calcium and magnesium decreases in the soil. But the amount of clay and the elements which are not yet the subjects to the irriga-tion (Si, Fe, Al) increases. Argillization is connected mostly with the decomposition of the carbonate particulars of sand and silt and with the riddance of aluminosilicate clay parts which are contained in carbonate rock (connected with the leaching of carbonates) and with the accumulation in the soil.
In noncarbonate soils the decomposition of aluminosilicate minerals and the improver-ishment from clay parts and ash elements take place.
Estonian automorphic and half hydromorphic soils are all denudational. Such conclusion comes from the soil’s characteristics and from the amount of the dissolved ingredients in the water of the rivers flowing into the sea (Tables 7, 8, 9).
Chemical denudation is a continuos process with growing intensiveness, nowadays in South-Estonia 20…30 mm during one thousand years. In North-Estonia more than 30 mm (Migratsii…, 1974). The mineral part of the soil degrades, which is expressed by the increase of the eluviahorizon’s forming level and by the increase of the horizon’s thickness in compen-sation for (at the cost of) the illuvial horizon.
In order to maintain and increase the potential fertility of soils it is needful to compen-sate among other things also the loss which is connected with the chemical denudation, i.e. the degradation of the mineral part of the soil in its natural evolution process.