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REHABILITATION OF THE STERILE DUMPS RESULTING FROM SURFACE MINING OF LIGNITE

Mihail Dumıtru

Abstract

The paper presents the results of the experiments on a sterile dump resulted from surface mining of lignite in Rovinari, Gorj County, where, was been tested the effect of a variety of fertilizer as: liquid fertilizers based on humates extracted from lignite, complex mineral fertilizer (N105 P105 K105 and N150 P150 K150), farmyard manure (20, 40 and 60 t/ha), compost (20, 40 and 60 t/ha), and the mixture of the two types of organic fertilizers with mineral fertilizer. Two test plants, corn, and sunflowers have been used. All the tested fertilizers have resulted in statistically assured harvest increases in both crops. The applied treatments led to statistically assured changes in soil chemical properties (pH, contents of humus, total nitrogen, mobile phosphorus, mobile potassium, cadmium, copper, cobalt, nickel, manganese, lead and zinc). For the corn crop, the best results were obtained in the treatment fertilized with 40 t/ha compost plus 100 kg N/ha, that provided a yield about 99% higher than control. The application of 60 t/ha of compost provided a yield increase of 82% and the humates-based liquid fertilizer at the dose of 150 l/ha provided a statistically assured yield increase of 55%. Sunflower crops have provided very significant production increases in fertilized variants with at least 40 t/ha compost, and those fertilized with complex mineral fertilizers. The analysis of corn leaves to determine the nitrogen, phosphorus, potassium, calcium, magnesium, copper, zinc, iron and manganese content did not reveal statistically significant changes under the influence of applied treatments.

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