Soil respread depths: Do we know enough to implement change?

Abstract

Current North Dakota soil respread regulations are based on research conducted in the mid 1980's. Regulations include a buffer that was added to the respread depths suggested by research to account for the unknown behavior of reclaimed sites over time as spoil weathers and plant communities mature. These unknowns have since been largely addressed by long-term studies of reclaimed sites. Studies have also shown that season of growth (C 3 vs. C 4) and origin (native vs. introduced) do not change the response of perennial grasses to soil respread depth. Therefore, respread recommendations may now be based on the results of research that include introduced species, and possibly without the addition of a buffer. After a review of literature it appears that respread depths may be reduced. A reduction in soil respread depths would result in less soil salvaged, stockpiled and respread, thus reducing reclamation costs for the mine without negatively effecting reclamation success. However, before changes to respread requirements are made, we must be confident this will not have a negative impact on the revegetation success of a site or of its capability to support other land uses in the future. Therefore, before ND mines can put into practice the recommendations of past research, issues regarding the effects on annual cropland, woody species and the behavior of sodium in the reclaimed soil profile must be resolved.