Behaviour of Major Chemical Elements in a Fire Affected Hillside from Lyulin Mountain, Bulgaria

I. ATANASSOVA, M. TEOHAROV and E. ZLATAREVA
Nikola Poushkarov Institute of Soil Science, BG – 1080 Sofia, Bulgaria

Abstract

ATANASSOVA, I., M. TEOHAROV and E. ZLATAREVA, 2011. Behaviour of major chemical elements in a fire affected hillside from Lyulin Mountain, Bulgaria. Bulg. J. Agric. Sci., 17: 348-356

We analysed the post fire effects from the late summer of 2007 on the behaviour of major chemical elements in surface soils and soil profiles (Luvisols and Gleysols) characterised as a catena sequence in a hillside of Lyulin Mountain, Bulgaria. The objectives of our study were to assess the P, N, K, Ca, Mg, Na contents in soils on the ridge and the hillside and define relationships between major chemical elements and other soil characteristics with the purpose to point at the origin and behaviour of these elements as influenced by fire. Distributions of available major chemical elements were compared to interpret processes and sources involved in element redistribution. Our key findings are the following: (1) changes concern mainly N, K, P and Mn and are related to significant increases in the upper surface (0-6 cm) layer; (2) no major changes in the exchangeable Ca and Mg contents in the surface of the burnt and unburnt control soils, as well as between the surface and the lower depths of the soil profiles were found, i.e. no additional release of bases as a result of burning was accounted for; (3) elevated concentrations of Na ions in the lower depths of the soil profiles and in the surface soils of the lower boggy parts of the hillside were related to the prevailing conditions of soil genesis. Statistical analysis including the burnt and unburnt control soils did not reveal any significant modifications in the major relationships between the measured parameters. The results show a biogenic source for the elements N, P, K, Mn, e.g. plant residues mineralization including fire induced. The elements Ca, Mg and Na did not increase in the upper layers of the burnt soils, but increased downwards the soil profile and were mainly related to the physico-chemical soil properties, such as cation exchange capacity and carbonate content and indicated a geopedogenic source.

Key words: forest fire; major chemical elements, exchangeable cations, biogenic source, geopedogenic source

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