2.1 Soil sampling
On August 16, 2020, soil was collected from a tailing slope of an
opencast coal mining area in Datan located in the Qilian Mountain (SE
Gansu province) (36°50′54″ N, 102°48′05″ E, 2650-2660 m), China. The
land use type around the sampling area is mainly natural grassland. The
area has a typical semiarid and cold temperate climate, with mean
temperature of about 16 °C and mean precipitation of about 375 mm in the
growing season (June to September). The soil types is Inceptisol under
the USDA Soil
Taxonomy system which characterized by nutrient impoverishment, sandy to
sandy loam texture, visible soil horizons and heavy metals content do
not exceed the standard. Five plots, 20×20 m2, were
randomly located in a tailing slope of an opencast coal mining area, in
which five soil samples(0-30 cm) were collected for each sample plot,
for a total of 25 soil samples. All soil samples were thoroughly
homogenized into one composite sample and sieved through a 4 mm sieve to
discard coarse fragments prior to incubation experiments. Mine soil
properties are shown in Table 1.