Reclamation of Abandoned Bentonite Mines in Wyoming with Woodwaste and Calcium Amendments to Mitigate Sodic Soils

Abstract

Abstract:The Wyoming Abandoned Mine Land Program has reclaimed 8635 acres of abandoned bentonite surface mines since 1985.Available minesoils were high sodium, heavy clay residual overburden materials with Exchangeable Sodium Percentages as high as 81.An amendment program to mitigate the clay and sodic problems was developed that included sawmill residues such as chips, bark and sawdust in combination with calcium compounds such as calcium chloride, gypsum and phosphogypsum or calcium compounds alone. The cost of the amendments varied depending upon sodium levels and the amendment or combinations used. Mean cost per acre for reclamation was $4879. 42 and . the combined amendments were 21.3% of the total reclamation cost. Reclamation completing its fifth growing season and subjected to livestock grazing during this period shows good visual performance. Additional