RESUMO
The main aim of these studies was to determine the potential for carbon sequestration in brown coal open-cast mine by phytoremediation using scots pine (Pinus sylvestris L.) and giant miscanthus (Miscanthus x giganteus) plants. This paper presents relationships between soil organic carbon (SOC) sequestration and carbon phytosequestration in waste dump associated with open-cast lignite mine in Central Poland. The research is the continuation of previously carried out experiments, but was conducted in field conditions. In reclamation of post-mining landscapes, during field experiment, an effect of sewage sludge, compost and lake chalk amendments and in combination of plants was investigated. The impact of soil amendments on carbon stock, CO2 emission reduction, plant biomass production and carbon content in shoots and roots was studied. The highest SOC stock was found in soil treated with sewage sludge (33 Mg*ha-1) and compost (45 Mg*ha-1) stabilized by lake chalk. These fertilizer combinations also contributed the most in relation to CO2 emission reduction through SOC stock (83 Mg*ha-1 and 127 Mg*ha-1 respectively). In addition, greater amounts (60-100%) of soil organic matter was converted into humic acids fraction. This phenomenon could be the initial stage of the progressive process of organic matter deposition and carbon sequestration in post-mining area. Carbon phytosequestration was determined through carbon bound in plant tissues. The highest carbon content (60%) in both plant species was recorded in treatments with sewage sludge and compost with lake chalk. Stabilization of compost by lake chalk application was good method to improve the efficiency of carbon sequestration in soil and carbon phytosequestration. Improving the efficiency of these two processes, through skillfully selected soil additives and plant species, may be used on a larger scale in the future as an alternative to the storage of carbon dioxide, especially in degraded areas.