EARLY STAGES OF LIGNITE MINE SOIL GENESIS - CHANGES IN BIOCHEMICAL-PROPERTIES

The evolution of N and P forms, C and phosphatase activity was studied in mine soils from a lignite mine in Galicia (N.W. Spain) from 1 to 3 yr after seeding. Total C and N contents, humus-associated N and humin N increased with soil age. Acid hydrolysis indicated an accumulation of amino acid N and unknown N fractions. All organic P fractions increased slightly. As the soil aged, the behaviour of phosphatase activity changed considerably as regards pH-dependence and kinetic and thermodynamic parameters. The data show that considerable humification took place in the 3 yr of pedogenesis, with some of the biochemical properties of the mine soils becoming similar to those found in the native soils of the area. Possible reasons for this rapid evolution are the characteristics of the parent material, intense rhizosphere activity and the climatic conditions of the area.