Articles | Volume 1, issue 2
Original research article
16 Sep 2015
Original research article |  | 16 Sep 2015

Soil biochemical properties in brown and gray mine soils with and without hydroseeding

C. Thomas, A. Sexstone, and J. Skousen

Abstract. Surface coal mining in the eastern USA disturbs hundreds of hectares of land every year and removes valuable and ecologically diverse eastern deciduous forests. Reclamation involves restoring the landscape to approximate original contour, replacing the topsoil, and revegetating the site with trees and herbaceous species to a designated post-mining land use. Re-establishing an ecosystem of ecological and economic value as well as restoring soil quality on disturbed sites are the goals of land reclamation, and microbial properties of mine soils can be indicators of restoration success. Reforestation plots were constructed in 2007 using weathered brown sandstone or unweathered gray sandstone as topsoil substitutes to evaluate tree growth and soil properties at Arch Coal's Birch River mine in West Virginia, USA. All plots were planted with 12 hardwood tree species and subplots were hydroseeded with a herbaceous seed mix and fertilizer. After 6 years, the average tree volume index was nearly 10 times greater for trees grown in brown (3853 cm3) compared to gray mine soils (407 cm3). Average pH of brown mine soils increased from 4.7 to 5.0, while gray mine soils declined from 7.9 to 7.0. Hydroseeding doubled tree volume index and ground cover on both mine soils. Hydroseeding doubled microbial biomass carbon (MBC) on brown mine soils (8.7 vs. 17.5 mg kg−1), but showed no effect on gray mine soils (13.3 vs. 12.8 mg kg−1). Hydroseeding also increased the ratio of MBC to soil organic C in both soils and more than tripled the ratio for potentially mineralizable nitrogen (PMN) to total N. Brown mine soils were a better growth medium than gray mine soils and hydroseeding was an important component of reclamation due to improved biochemical properties and microbial activity in mine soils.

Short summary
Surface coal mining disrupts large areas of land and eliminates valuable hardwood forests. Restoring the land to a sustainable forest ecosystem with suitable soils is the goal of reclamation. Soil microbial activity is an indicator of restoration success. We found hydroseeding with herbaceous forage species and fertilization doubled tree growth and microbial biomass carbon (an indicator of microbial activity) compared to non-hydroseed areas. Hydroseeding is an important component of reclamation.