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that the best indicator regarding the revegetation potential should be individual plant <br />species response. Therefore, in the following discussion, plant species response as <br />defined by the two target plant species which are most valuable to the landowner in the <br />postmining situation are addressed. The two target species are Alfalfa and Smooth <br />Bromegrass as these two plants hold the most economic value to the landowner in the <br />post- mining situation. <br />Working at the Energy Mine, near Oak Creek, CO, Crofts and others 1987, compared <br />plant growth on four different soil horizon treatments (topsoil, subsoil, topsoil over <br />subsoil and topsoil /subsoil mixed) as well as 0 cm, 10 cm, 20 cm, 30 cm and 46 cm <br />depths of respread topsoil on plots constructed in 1976 and monitored in 1985. See <br />Appendix 2.05.4(2)(d) -2. Total plant cover nine years after plot establishment averaged <br />85.3 percent total on the A/B plots and 82.3 percent on the AB mixed plots. There was <br />no statistical difference in total plant cover when the topsoil over subsoil plots were <br />compared to the mixed topsoil - subsoil plots. With respect to individual plant cover, <br />Alfalfa cover was highest on the mixed topsoil- subsoil plots, 65.3 percent when <br />compared to the topsoil over subsoil plots, 54.3 percent. Smooth Bromegrass cover <br />highest on the topsoil over subsoil plots, 5.3 percent as compared to the 3.2 percent <br />associated with the mixed topsoil- subsoil plots. Mean cover of individual species was <br />not subjected to statistical analysis. <br />Total forage production on the topsoil over subsoil plots averaged 4,840 kg /ha as <br />compared to 4,552 kg /ha for the mixed topsoil- subsoil plots. There was no statistical <br />difference in total forage production when the topsoil over subsoil plots were compared <br />to the mixed topsoil - subsoil plots. Given the higher cover of Alfalfa associated with the <br />mixed topsoil - subsoil plots as compared to the topsoil over subsoil plots, the data from <br />this study clearly do not support the contention found in the DRMS regulations that <br />segregation of topsoil and subsoil might be necessary for successful reclamation <br />involving Alfalfa and Smooth Bromegrass. <br />In topsoil segregation and depth studies established in North Dakota in 1974 and <br />monitored from 1976 through 1979, Powers and others (1981) reported on the <br />productivity of Alfalfa planted on plots with subsoil thickness ranging from 0 to 190 cm <br />Section 2.05.4(2)(d) Page 15 January 2012 <br />