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United States Department of Agriculture

Agricultural Research Service

Research Project: Develop Improved Plant Genetic Resources to Enhance Pasture and Rangeland Productivity in the Semiarid Regions of the Western U.S.

Location: Forage and Range Research

Title: Germination, biomass production, and root growth in range restoration grasses on Se overburden soils

Authors
item Jensen, Kevin
item Davis, Thomas
item Panter, Kip
item Larson, Steven

Submitted to: International Symposium on Poisonous Plants
Publication Type: Proceedings
Publication Acceptance Date: December 20, 2013
Publication Date: N/A

Interpretive Summary: Currently, many of the phosphate mines in Southern Idaho are experiencing Selenium (Se) poisoning of livestock and suspected wildlife. Selenium in its elemental form is not toxic, but once exposed to O2 during the mining process for selenate and selenite which are toxic to livestock. There are two protocols currently used for remediation 1) use of a cover cap over Se overburden piles, and ii) seed directly into the Se overburden with plant materials that are not Se accumulators. Species included in this study were big bluegrass, western wheatgrass (WG), mountain and smooth bromegrass, orchardgrass, prairie junegrass, pubescent WG, sheep fescue, slender WG, tufted hairgrass, Siberian WG, and Russian wildrye. The objectives of the study were to 1) identify species (above) capable of germinating in Se overburden soil (control, cap material, 16_ppm, 35_ppm, and 70-ppm), and 2) evaluate Se uptake in species grown on the soils above. With exception of the 70_ppm Se soil (9.7 seedlings per day), there were no differences in the rate of seedling emergence (11.1 to 11.4 seedling per day) between the control, cap, 16_ppm, 35_ppm soils. Depth of the dinwoody cap used in this study had little influence on plant and root biomass production and root length. However, when plants were grown directly in 36 ppm Se soil, there was a significant reduction in plant and root biomass and root length. Across all treatments, mountain and meadow brome and intermediate wheatgrass performed better than the other grasses with mountain brome being the best.

Technical Abstract: During the past 15 years, several of the historical reclaimed phosphate mines in Southeastern Idaho have experienced selenium (Se) poisoning of livestock and suspected poisoning of wildlife. Selenium in its elemental form is not toxic and not bioavailable to plants, but once exposed to O2 during the mining process, elemental Se is oxidized to selenite and then to selenate which makes the Se bioavailable for uptake by plants and subsequently toxic to livestock. The purpose of the current research is to find forages that can be used in the overburden soils that can be more effectively used to reduce the risk of poisoning of livestock and wildlife. Species included in this study were big bluegrass [Poa secunda J. Presl], western wheatgrass (WG) {Pascopyrum smithii (Rydb.) A. Love], mountain [Bromus marginatus Nees ex Steud.] and smooth [Bromus inermis Leyss.] bromegrass, orchardgrass [Dactylis glomerata L.], prairie junegrass {Koeleria macrantha (Ledeb.) Schult.], pubescent WG {Thinopyrum intermedium (Host) Barkworth & D.R. Dewey], sheep fescue [Festuca ovina L.], slender WG [Elymus trachycaulus (Link) Gould ex Shinners], tufted hairgrass [Deschampsia cespitosa (L.) P. Beauv.], Siberian WG [Agropyron fragile (Roth) P. Candargy], and Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], and western aster. The objectives of the study were to 1) identify species (above) capable of germinating in Se overburden soil (control, cap material, 16_ppm Se, 35_ppm Se, and 70_ppm Se), and 2) evaluate above and below ground production and root length as effected by exposure to seleniferous soils. Depth of the dinwoody cap used in this study had little influence on plant and root biomass production and root length. However, when plants were grown directly in 36 ppm Se soil, there was a significant reduction in plant and root biomass and root length. Across all treatments, mountain and meadow brome and intermediate wheatgrass performed better than the other grasses with mountain brome being the best.

Last Modified: 9/10/2014
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