RECULTIVATION OF DEGRADED SOIL DUE TO MINING ACTIVITY WITHOUT ADDING ORGANIC LAYERS OF SOIL USING ALFALFA AND MIXTURES OF GRASS LEGUMES
Biotechnical Faculty of the University of Montenegro
The aim of this research was to examine the possibility of reparing the chemical properties of substrate and regenerating the vegetation of degraded soil due to mining activity without adding the fertile soil layer. The research was carried out in the period 2011-2013 on degraded soil of mine and thermal power plant Gacko. The experiment was placed on a landfill located in Srđevići. For these tests, grass-leguminous mixtures were used: I/G (alfalfa 70%, orchard grass 30%); II/G (alfalfa 70%, orchard grass 15%, tall oat-grass 15%); III/G (red clover 50%, italian rye-grass 50%); IV/G (alfalfa 30%, tall fescue 40%, smooth brome15%; orchard grass 15%) and alfalfa 100%. The following parameters were monitored and analyzed during the tests: mechanical soil composition, soil chemical properties, microelement content in the soil: Zn, Mn, Fe, Cu; the content of heavy metals in the soil: Pb, Ni, Cr, Cd, Hg, As, plant species presence in the mixture, soil cover with grass, yield of green mass by cuts and years, content of microelements and heavy metals in dry vegetable mass by cuts and influence of nitrate content of individual microelements and heavy metals in soil and dry mass of plants. Studies of the content of microelements and heavy metals in degraded soil showed that it contained Cd in significantly higher value than the permitted limit value. Other elements were within the limit values permitted for agricultural land. The content of Cd in 2011 was 5.1 mg kg-1 of soil, and in 2013 it was 4.5 mg kg-1 of soil. By analyzing the composition of the green matter in mixtures I/G, II/G and IV/G, it was found that orchard grass was predominantly present in relation to other constituents of the mixture. The III/G mixture was dominated by Italian rye-grass. The participation of other plant species in the mixture was extremely low. In the green mass of all mixtures, leguminous was represented in a small percentage. The largest soil cover with plants was achieved with the mixture IV/G (88.4%), which at the same time achieved the highest average yield of green mass. The determined values of the content of microelements and heavy metals in the dry mass were within the allowed limits. Nitrates influenced the reduction of Cu and Cr content in soil and Cd content in dry plant mass.
degraded soil, recultivation, alfalfa, grass-leguminous mixtures