Reclamation and Fertilization of Coal Mine Soils in the Southwestern Desert

Abstract

A 5 -year experiment was conducted from 1978 through 1982 on the Black Mesa Coal Mine, Kayenta, Arizona, to study plant species best suited for coal mine reclamation and the effects of fertilizer on selected species. Five plant species were broadcast seeded on coal mine soil (spoils) and unmined soil. Prior to planting, 560 kg /ha of 16-20-0 fertilizer were applied on one -half of each site while the other half received no fertilizer. Immediately after planting, sprinkler irrigation water was applied on all plots, as needed, for the first two years. After two years, fertilizer and irrigation were discontinued on both soil materials and all plant species received only natural rainfall for the following three years. Coal mine soil contained more total soluble salts, nitrogen, potassium, sodium, and organic matter than did unmined soil; however, unmined soil had a higher pH and contained more phosphorous than did coal mine soil. Plant growth measurements were recorded for each plant species in October of each year. In general, plants grew better and produced more forage in unmined soil than they did in coal mine soil. All plant species grew better, yielded more forage, and produced a more satisfactory ground cover when they were fertilized than they did when they were not fertilized. Plant species differed greatly in general growth, forage yield, and percent ground cover within soil materials and within fertilizer treatments. Crested wheatgrass (Agropyron cristaturn L.), western wheatgrass (Agropyron smithii Rydb.), and vernal alfalfa (Medicago sativa L.) grew better, yielded more forage, and produced a more complete ground cover than did Indian ricegrass (Oryzopsis hymenoides Ricker) or fourwing saltbrush (Atriplex canescens Pursh). In general, the reclamation of unmined soil with fertilizer and a combination of natural rainfall and sprinkler irrigation during the first two years and with perennial grasses was more successful than the reclamation of coal mine soil with no fertilizer and with legumes or shrubs in the semiarid environment in the southwestern United States.