Environmental Rehabilitation of Mining Dumps

Mining exploitations, especially the surface ones, severely degrade the environment by removing large areas from agricultural and forestry use, micromorphological changes, hydrogeological and hydrographic changes, air, water and soil pollution, flora and fauna losses, microclimate changes, historical and archaeological sites damages, displacements of settlements and transport routes. Results obtained following the agrochemical experiments show that increasing the doses of fertilizers had positive effect on yields of all the tested crops.This paper presents several experimental fertilizers: four liquid fertilizers associating humic substances extracted from lignite with a complex matrix containing macronutrients (nitrogen, phosphorus, and potassium) and trace elements (copper, zinc, iron, manganous, boron); two types of organo-mineral fertilizers with macronutrients on a lignite carrier; two types of organic fertilizers (containing cattle manure or compost obtained from cattle manure, lignite powder and potassium humates). These experimental fertilizers were tested - alone or associated with mineral fertilizers - on maize, sunflower and peas crops.In all three experimental years, and for all three crops, the best yields were obtained for the variants fertilized with 40 t/ha compost + N100P80K80. Thus, a 364% average yield increases were recorded for maize, 310% for sunflower and 156% for peas crop, compared to the control plot (unfertilized). For maize crop, the following yield increases have been recorded, comparing to the control plot: 165% for mineral fertilization (N100P80K80); 253% for the variant with 40 t/ha cattle manure; 277% for the variant with 40 t/ha cattle manure + N100P80K80; while the variant with 40 t/ha compost led to a 256% yield increase. Regarding the variants with organo-mineral fertilizers, yield increases between 196% and 229% were obtained, as compared to the control plot. Liquid fertilizers with humic substances extracted from lignite highlighted very significant yield increases (135-158%). Similar observations were recorded for sunflower and peas crops.