Effects of reclamation and deep ripping on soil bulk density and hydraulic conductivity at legacy surface mines in northeast Ohio, USA

Abstract

Surface mining and reclamation activities can substantially affect the soil physical properties that mediate water movement and root growth, impeding the re-establishment of native vegetation and ecosystem function. Deep ripping is a promising approach to mitigate compaction using long shanks dragged through the soil, but little is known about its effectiveness in fine-textured glacial parent material. In five reclaimed surface mines and four reference forests on glacial parent material, we measured soil bulk density and saturated hydraulic conductivity. Two mine sites were subsequently subjected to deep ripping in a grid pattern and soil properties were remeasured within and outside of the rips. Before ripping, near-surface bulk density was higher and saturated hydraulic conductivity was lower at the reclaimed mines than the reference forests, and mine soils deeper than 20 cm were often denser than ideal for plant growth (>1.4 g cm−3). Ripping increased variability in bulk density and saturated hydraulic conductivity, with the intersection of perpendicular rips becoming denser than pre-rip conditions in the top 5 cm. Below the surface, soils in the rips were generally less dense than pre-rip conditions, and soil piping was observed within some rips. Between the rips, bulk density decreased in the top 5 cm, but remained constant or increased relative to pre-rip conditions at greater depths. These results emphasize the importance of fine-scale, spatially explicit sampling when assessing the effects of mine reclamation and ripping. Our data support strategies of planting trees within rip intersections, though cast doubt on the potential for root expansion into areas between rips.

Keywords

• Mine reclamation
• Soil properties
• Deep ripping
• Bulk density
• Saturated hydraulic conductivity
• Root restriction