Laserfiche WebLink
topsoil. The results after nine growing seasons <br />were compared to regulatory success standards <br />of plant cover, annual biomass production and <br />species diversity. Furthermore, the applicability <br />of this study relative to cost savings involving <br />topsail reapplication, is addressed. <br />MATERIALS AND METHODS <br />Study Site <br />The study was conducted at the Energy Mine <br />No. 1 of Colorado Yampa Coal Company (formerly <br />Energy Fuels Corporation) located 32 km southwest <br />of Steamboat Springs, Colorado. Elevation of <br />the study site is approximately 2,250 m and <br />the long term average annual precipitation c the <br />410 ma. Approximately <br />precipitation is received in the form of snow. <br />The area was surface mined in the early 1970 "s <br />and reclaimed in 1975. Vegetation on the site <br />prior to mining consisted of scattered mountain <br />shrub•, treated sagebrush and aspen (BBergisand <br />nd <br />Barrau 1973). The regraded spoil <br />of a mixture of shale and sandstone strata from <br />the Williams Fork Formation of the Upper <br />Cretaceous Mesa Verde Group. The soils used <br />in these studies were mapped according to standard and <br />taxonomic procedures prior to disturbance u rtnd <br />sampled for chemical and physical rertin <br />prior to mining and again following resp g <br />(Heil 1978). <br />The predisturbance soil survey revealed <br />the barrow area contained three distinct soils. <br />The horizon segregation plots were constructed <br />with a soil classified as a fine- mantmorillonitic <br />family of Typic Argiborolls. The topsoil of <br />this soil was rated "excellent" while the subsoil <br />was rated as being of "good to poor" suitability <br />(Heil 1978). Two azonal soils classified as <br />a fine - loamy, mixed family of Pachic Haplobo oils <br />and a fine - loamy, mixed family of Lithic <br />Haploborolls rated as "excellent" suitability <br />were used in the topsoil depth plots. The <br />physical and chemical properties of the topsoils, <br />subsoil and spoil materials used in this study <br />are found in Table 1, Physical and Chemical <br />Characteristics of Soil and Spoil Materials. <br />Further details of the environmental and <br />climatic conditions of the site during the first <br />two years of the study is described in Nicholas <br />(1979) and McGinnies and Nicholas (1980). <br />Plot Construction <br />The horizon segregation study plots measuring <br />23 x 61 m were established on A, A over B (A /B), <br />B and AB mix soil horizons. All treatments <br />were placed over regraded spoil material. The <br />A the surface plots <br />cm layer constructed <br />bar ow area and <br />TABLE 1.-- PHYSICAL AND CHEMICAL CHARACTERISTICS <br />OF SOIL AND SPOIL MATERIALS <br />TOPSOIL DEPTH HORIZON SEGREGATION <br />A A <br />PARAMETER <br />PH <br />EC <br />SAR <br />Sand (%) <br />Silt ( %) <br />Clay (%) <br />Texture <br />NO -N (ug /g) <br />P (ug /g) <br />K (ug /g) <br />Fe (ug /g) <br />Zn (ug /g) <br />CSC <br />0.M. ( %) <br />1/3 Bar Water ( %) <br />15 Bar Water ( %) <br />6.7 6.2 <br />0.7 0.9 <br />0.9 1.4 <br />45.5 25.5 <br />27.0 41.5 <br />27.5 33.0 <br />CL CL <br />27.7 43.0 <br />23.6 20.0 <br />273 282 <br />57.3 82.5 <br />2.3 3.6 <br />21.9 23.4 <br />5.4 5.0 <br />22.6 28.4 <br />11.5 14.3 <br />B SPOIL <br />6.1 7.4 <br />1.7 2.2 <br />1.5 0.6 <br />24.0 <br />- 47.3 <br />- 28.7 <br />CL <br />26.0 5.1 <br />6.0 4.5 <br />122 <br />61.6 38.3 <br />1.1 6.8 <br />23.7 11.3 <br />2.0 3.2 <br />- 20.2 <br />10.9 <br />reapplying the material approximately 30 cm <br />deep over the spoil. The A/B horizon plots <br />were constructed by applying ,15 cm of the B <br />from the material <br />to over depth o removed <br />of the barrow area. <br />Fifteen centimeters of the A horizon material <br />was placed over the 8 horizon to establish a <br />total treatment depth of 30 crn. The 8 horizon <br />plots were constructed be removing the thickness <br />found in the 30 to 45 cm zone of the barrow <br />area and replacing it to thickness of 30 cm <br />over the regraded spoil. The AB mixed horizons <br />were constructed by removing the undisturbed <br />15 to 30 cm zone, containing both A and 8 horizons <br />and replacing this material at a thickness of <br />30 cm. <br />The soil thickness plots, 18 x 61 m in <br />size, were constructed by removing A horizon <br />material and respreading it on regraded spoil <br />at depths of 0, 10,©0, and 46 <br />both cm. <br />the Fo <br />top all plots <br />segregation and topsoil depth plots were bladed, <br />disked and seeded. The plots were seeded with <br />a diverse seed mixture composed of 13 exotic <br />and 23 natives species. The plant species and <br />seeding rates are depicted on Table 2. All <br />of the plots were seeded in October 1976. Each <br />plot was replicated twice in a block design. <br />Data Collection and Analysis <br />Plant cover data was collected in 1979, <br />1981 and 1985 using the inclined 10 point frame <br />cover estivate technique. For all years, a <br />sufficient number of randomly located samples <br />wera taken within each plot. Each point was <br />recorded as to individual plant species, litter, <br />bareground or rock. <br />