E. VELIZAROVA1, I. VELICHKOV1, V. DOICHINOVA1 and I. ATANASSOVA21 Bulgarian Academy of Sciences, Forest Research Institute, BG - 1756 Sofia, Bulgaria
VELIZAROVA, E., I. VELICHKOV, V. DOICHINOVA and I. ATANASSOVA, 2013. Exchangeable properties of forest soils under beech ecosystems in Central Balkan and Osogovo. Bulg. J. Agric. Sci., 19: 939-945
For forest soils, which are naturally acidic, there is only a limited number of reports, concerning their cation exchange capacity (CEC) controlling mechanisms and on the possible impacts of acidic deposition, climate change and increasing harvesting pressure for biofuels. Therefore, the aim of this investigation was to characterise the cation exchange capacity of forest soils (Dystric and Eutric Cambisols) under beech stands (Fagus sylvatica L.) from the Central range of the Balkan mountain and from the Osogovo Mountain. The cationexchange properties have been analyzed following the methodology of Ganev and Arsova (1980). The cation exchange capacity (T8.2) in the surface horizons of soil samples from the Balkan mountain vary within a wide range of 10.6 cmol.kg-1 to 20.9 cmol.kg-1. For the soil from the Osogovo Mountain, the total cationexchange capacity was higher ranging from 18.4 cmol.kg-1 - 34.4 cmol.kg-1. The concentrations of negatively charged strongly acid exchangeable sites (TCA) were from 6.0 to 15.5 cmol.kg-1, for the soil from the Balkan mountain, while for the Osogovo Mountain - they were about two times higher - from 12.0 cmol.kg-1 to 27.1 cmol.kg-1. A similar trend for the exchangeable aluminium (Ale) values for the surface horizons of the Balkan mountain soil (from 1.0 cmol.kg-1 to 2.5 cmol.kg-1) and of the Osogovo Mountain, soil (from 1.6 cmol.kg-1, to 5.9 cmol.kg-1) was established. The slight increase in the content of Ale in the soil from Osogovo Mountain suggests a stronger destruction of Al-bearing minerals, most probably due to isomorphic substitutions. It was found that podzolization was occurring more pronouncedly in the soils of the Balkan mountain. The base saturation (BS) in the studied soils varies from 33.0 to 75.0% of the total cation exchange capacity. For all studied sampling sites, the negative charges of soil colloids which behave as strong acids (TCA) exceed the BS values, due to the additional proportion of H+ and Al3+ acidic cations.