English

Abstract

A study was conducted to examine the impacts of land reclamation and management practices on the saturated infiltration rates (Ks) and bulk densities (BD) of soils in reclaimed surface coal mines of Wyoming. The use of direct- hauled topsoil vs. stockpiled topsoil, hay mulch vs. stubble mulch, grazing vs. no- grazing, and standard seed mixes (grass seeding) vs. shrub mosaic seed mixes as surface coal mineland reclamation practices were studied in five coal mines of the Powder River Basin, the Green River Coal Region and the Hanna Coal Field in Wyoming. Results from the reclaimed sites with the above listed management practices were compared to each other and with representative soils from adjacent native undisturbed sites. In all the study sites, native undisturbed soils had the lowest BD and the highest Ks compared to reclaimed soils. At Jim Bridger mine, results indicated no differences in BD and Ks between stockpiled and directly hauled soils. At the Belle Ayre mine, there was no significant difference in Ks between reclaimed soils and native undisturbed soil. At Seminoe mine, reclaimed stubble mulched soil had greater Ks (9.208 mm/min) than native undisturbed soil Ks (6.042 mm/min). At Jacob's Ranch, ungrazed soils had greater Ks (6.958 mm/min) than grazed soils Ks (3.350 mm/min) and native undisturbed soils (3.833 mm/min). BD at 0-5 cm for grazed soils was also greater (1.462 g/cm 3 ) than for ungrazed soils (1.255 g/cm 3 ) . Native undisturbed soils had the lowest BD (1.116 g/cm 3 ) averaged over all depths. Although native undisturbed BDs were generally lower, their Ks were not always greater. These results suggest that removal and manipulation of soil during mining accompanied by heavy machinery traffic over reapplied topsoil during reclamation may cause some degree of soil compaction relative to undisturbed sites. However, it can be concluded that land reclamation and management measures taken during and after mining may help to improve infiltration rates.