Role of Chelating Processes in Formation of Buffer Systems under Organo-mineral Melioration of Cu and Zn Polluted Acid Soils (II)

T. RAYCHEV1, A. ARSOVA1, S. POPANDOVA1, G. JOZEFACIUK2, Z. SOKOLOWSKA2 and M. HAJNOS2
1 N. Poushkarov Institute of Soil Science, BG-1080 Sofia, Bulgaria
2 Institute of Agrophysics, Polish Academy of Sciences, Doswiadczalna 4, P.O. Box 201, 20-290 Lublin 27, Poland

Abstract

RAYCHEV, T., A. ARSOVA, S. POPANDOVA, G. JOZEFACIUK, Z. SOKOLOWSKA and M. HAJNOS, 2001. Role of chelating processes in formation of buffer systems under organo-mineral melioration of Cu and Zn polluted acid soils (II). Bulg. J. Agric. Sci., 7: 167-174

The present study performs a general discussion on the role of chelating processes in formation of buffer systems under an organo-mineral melioration of heavy metal polluted acid soils. Results obtained during pot experiments with alfalfa under different rates of waste carbonate deposit and coal powder applied in Cu, Zn and Cu + Zn polluted soils are discussed. The practical interest is to optimize the ratios between the organo-mineral soil components for plant growth. This aim provides some general formulas presented in the study, which are useful for organo-mineral liming heavy metal polluted acid soils.
The intra-molecular rearrangement between coordination and valent bounds of the internal cation and ligands in anionic part of the complex heteropolar salts appears to be one of the dominant mechanism involved in pH-buffering reactions of humic compounds. This mechanism is limited by the respective coordination capacity of the organic compounds and is manifested at ratios of the amendments (carbonate deposit : coal powder) between 1: 4 and 1: 16. At ratio ³ 1: 12 the depressive effect on the testing plant yield was observed. This was interpreted as due to binding of part of the nutrients by the excess of acidic groups of the humic compounds added.

Key words: acid soils, chelating processes, copper and zinc pollution, organo-mineral liming, alfalfa yield