2002-07-08_GENERAL DOCUMENTS - M2002004 (4)

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Table 18. Average moisture levels in the top 5 feet of the Falkirk trench plots at planting and at harvest from 1979 to 1982 averaged for all topsoil thicknesses 14 Table 19. Yields of small grains and corn on undisturbed and reclaimed soils at the Knife River Mine at Beulah and the Baukol- Noonan Mine at Center 15 Table 20. Available soil water at various soil depths at Carrington in 1971 between wheat planting to harvest. Wheat yield was 39 bushels per acre. Adapted from Bauer (1980) 16 Table 21. Suggested guidelines for soil replacement based upon spoil properties 19 FIGURES Figure 1. Yields of crested wheatgrass with and without 12 inches of topsoil at four sites with different SAR values (Merrill et al., 1981) 6 Figure 2. Effect of topsoil depth over sodic minespoil on stand density of crested wheatgrass (Ries et al., 1978) 6 Figure 3. Schematic diagram illustrating the construction of the subsoil wedge (Step 1) and placement of topsoil over the wedge (Step 2) in the Stanton wedge experiment 8 Figure 4. Schematic design illustrating the construction of the Zap double wedge experiment (Merrill et al., 1982b) 10 Figure 5. Average relative yields of spring wheat (1976 and 1978) and crested wheatgrass (1978, 1979, 1981) as affected by topographic location, total soil thickness and subsoil material at the Zap double wedge experiment. Average yield for each crop assigned relative yield 1.0 11 Figure 6. Cross - section of a trench in the Falkirk experiment showing the place- ment of topsoil, subsoil, and overburden materials. Subsoil was replaced in only one treatment (gls + subsoil); in the other three treatments, top- soil was replaced directly over the overburden at depths of 9, 18, and 27 inches 12 Figure 7. Yield of wheat in 1979 and 1982 as affected by microtopography (eleva- tion) of different topsoil depths in the trench filled with silty clay loam overburden 13 3