SOIL DEVELOPMENT IN TWO OHIO MINESOILS UNDER CONTINUOUS GRASS COVER FOR TWENTY-FIVE YEARS FOLLOWING RECLAMATION

摘要

During 2001, two Ohio surface mined sites were re-examined to assess soil development in Bethesda and Fairpoint minesoils that have been in continuous, tall cool-season grass cover, principally tall fescue (Festuca arundinacea Shreb.), since reclamation in 1975-76.11581158 Topgrowth was cut and removed from 1979- 94 while being utilized for forage research. Bethesda (loamy-skeletal, mixed, acid, mesic, Typic Udorthent) and Fairpoint (loamy-skeletal, mixed, nonacid, mesic, Typic Udorthent) have each been mapped on more than 60,000 hectares of minespoils in Ohio and neighboring states. Five years after reclamation (1981), morphological descriptions and physical and chemical characterization of samples collected from pits showed negligible evidence of pedogenesis. Twenty-five years after reclamation, morphological descriptions and physical and chemical analyses of samples were again obtained at these sites. During the 20 year interval from 1981 to 2001, organic carbon content has increased >= 2.6 dollars-fold in the surface 9 to 11 cm, soil structure now extends 23 to 27 cm below the Ap horizon into the spoil, soil consistence has become more friable, rooting depths have increased, the release and oxidation of Fe has yielded higher chroma colors in the uppermost portion of the spoil, significant quantities of extractable Na and K have been released by mineral weathering, and calcite has been removed from the Fairpoint minesoil by dissolution. These changes indicate that significant soil development has occurred during this 20 year period. Whereas the minesoils were described in 1981 with only A and C horizons, the uppermost portion of the spoil in 2001 was described as a Bw horizon in Bethesda and as a CB horizon in Fairpoint. Because both the Bw and CB horizons qualify as cambic horizons, both the Bethesda and Fairpoint minesoils now classify as Dystric Eutrudept and Typic Eutrudept, respectively.