Soil formation processes in the gangue heaps resulted in surface mining in Cluj County (Romania)

Author: Doina Clapa ^1*, Teodor Rusu ^2*, Ioan Pacurar ² and Alexandru Fira ¹

Received 27 September 2008, accepted 29 December 2008.

Abstract

The paper presents the soil formation processes that take place in the gangue heaps resulted from iron mining ore at Căpuş quarry, Cluj County, Romania. The gangue which resulted was transported and piled up into heaps, without uncovering and a selective separation of the layers, such a low- fertility material resulted. This heap was partially levelled and used in plantation of pine (Pinus sylvestris), perennial gramineae (Lolium perenne, Dactylis glomerata, Phleum pratense), locust (Robinia pseudacacia) and spruce fir (Picea abies). After 25 years of recultivating, profiles were opened under the pine and gramineae plantations and physical and chemical analyses were carried out and compared to those of the initial heap. An evolution of the main pedogenetical indices (pH, humus, total nitrogen and mobile phosphorus and potassium) was observed in both of the studied profiles. The results show that after 25 years of planting the gangue heap with the two cultures, some layers of soil were formed, which, in a certain extent, have characteristics of the pedogenetic horizons, the evolution of the entianthrosoils towards a certain soil type being evident. The soil towards which these entianthrosoils evolve is of the Regosoil type.

Key words: Mining, gangue heaps, entiantrosoil, soil formation, humus, pH.