Study on Soil Fertility of a Robinia pseudoacacia Plantation in an Abandoned Iron Tailing Area in Huangshi

Soil characteristics of a Robinia pseudoacacia plantation was investigated in an abandoned iron tailing area in Huangshi City to provide guidance for soil remediation of abandoned mine lands. Soil pH, organic matter, total N, total P, total K, alkali-hydrolyzable N, available P, and available K were determined by routine method, the number of diazotrophs and the phosphate-solubilizing bacteria number were determined by dilution plate method, and activities of soil urease, phosphatase and catalase were determined by colorimetry, disodium phenyl phosphate colorimetric method and titration with potassium permanganate, respectively. The contents of soil organic matter, total N, total P were 101.5, 2.8, 1.5 g·kg^-1, and alkali-hydrolyzable N, available P, and available K were 130.7, 16.2, 201.8 mg·kg^-1 respectively in the soil of the R. pseudoacacia plantation, which were significantly greater than those of the abandoned iron tailing without vegetation, while total K was lower by 13.7% compared with the control. The number of diazotrophs and phosphate-solubilizing bacteria were 75.0×10⁵ and 85.7×10⁵ cfu·g^-1 respectively, and activities of urease, phosphatase and catalase were 2.7 g·kg^-1·d^-1, 317.6 mg·kg^-1·h^-1 and 4.6 mL·g^-1·h^-1, respectively, which were significantly greater than those of the controls. Soil structure of the abandoned iron tailing was improved and nutrient content was increased because of covering mixed substrate, which facilitated the colonization of R. pseudoacacia, and the growth of R. pseudoacacia further improved soil properties and facilitated the ecological restoration of abandoned iron tailing.