Soils development in opencast coal mine spoils reclaimed for 1-13 years in the West-Northern Loess Plateau of China

Soil development is the key process of mine spoil reclamation. To investigate the effects of different plant species and reclamation time on the soil development, 9 plots in the reclaimed spoils of Pingshuo opencast coal mine in Shanxi, China were established and the physical, chemical and microbiological properties of the soils were analyzed. The results showed that, soil bulk density and field capacity in plots with longer reclamation time were statistically different from plots with younger vegetation in both the 0 -20 cm and 20-40 cm soil layers. Accordingly, values of organic matter and available nitrogen levels showed a significant increase in both 0-20 cm and 20-40 cm depth with reclamation time increasing and the top layer marked higher value except for some individual data. The organic matter in plot 8 in 0 -20 cm depth with 13-year old vegetation reached 9.45 g kg(-1), about 2.5-, 2.0- and 3.1-fold higher than the plots of 1-, 3- and 4-year old vegetation respectively. Total microbial amount showed a positive correlation with contents of organic matter which reached 1436.72 x 105 g(-1) in plot 8 with 13-years old vegetation, about 11.3-fold greater than plot 1 of 1-yr old vegetation. Plots planted with sea buckthorn (Hippophae rhamnoides ssp. sinensis) singly or mixed with other species tend to develop better soil aggregation and microbiological properties than other plots, which may be due to its particular biological characteristics, developed root system and high growth rate in the first 4-6 year and 8-10 year, indicating that sea buckthorn may be a good species choice for activating soil development in the early stage of reclamation. (C) 2012 Published by Elsevier Masson SAS.