Salt Tolerance of Two Saltbush Species Grown in Processed Oil Shale

Abstract

The tolerance of fourwing saltbush (A triplex canescens) and cuneate saltbush (Atriplex cuneata) to the salts in processed oil shale was studied in a greenhouse experiment over an ECe range of 4 to 38 mmho/cm. Growth responses differed, depending on the species and the particular salt or salts in the soil solution. Cuneate saltbush was more salt tolerant than fourwing saitbush, but both species survived and grew at salinities as high as 38 mmho/cm. Because of their high salt tolerance these saltbush species may be very important for use in the rehabilitation of processed oil shale disposal sites. Commercial scale surface retorting of oil shale will result in large amounts of processed shale that may be deposited in canyons as land fill. Any lessee of federal prototype oil shale lands is required to rehabilitate affected lands to a useable and productive condition. .compatible with existing adjacent undisturbed natural areas. .that will support fauna of the same kinds and in the same numbers as existing at the time the basline data were obtained. . (Federal Register 1973). Establishment of vegetation must be considered as one of the prime steps of rehabilitation. One of the major obstacles to successful plant establishment on processed oil shale is high salinity. Electrical conductivities of saturation extracts (ECe's) of several processed shale samples ranged from 9 to 26 mmho/ cm in studies of Schmehl and McCaslin (1973) and from 5 to 22 mmho/cm in our studies (Institute for Land Rehabilitation 1979). Soils are usually considered saline when ECe values reach 4 mmho/cm (Richards 1954). In addition to the total salinity, as measured by EC, the specific ion composition of the shale may have important effects on plant growth as well. The predominant soluble salts in processed oil shale are sodium sulfate and magnesium sulfate, while concentrations of chloride salts are relatively low (Schmehl and McCaslen 1973). For example, the first liter of leachate obtained from columns of paraho processed oil shale at Utah State University contained 509 milliequivalents per liter (meq/ l)Na +, 436 meq/ 1 Mg++, 882 meq/ 1 SO4'and only 14.1 meq/ 1 CL(Institute for Land Rehabilitation 1979). The leachate also contained 23.5 meq/l Ca,19.3 meq/ I K+, and 1.6 meq/l HCO3 Two plant species of interests for rehabilitating processed oil shale in Utah are fourwing saltbush (Atriplex canescens) and cuneate saltbush (Atriplex cuneata). Both species are native to the federal oil shale lease tracts, U-a and U-b, in eastern Utah (VTN Colorado, Inc. 1977). The species are noted for their salt and drought tolerance and their forage value (Blauer et al. 1976). These two species occupy different Authors are research associate and director, Institute for Land Rehabilitation, Utah State University, Logan 84322. This study was conducted as a project of the Institute for Land Rehabilitation, Utah State University, and was supported by funds from the White River Shale Project, Vernal, Utah. Manuscript received July 13, 1979. habitats and may have different soil requirements and salt