Figure 18.— Experimental water detention terraces at the San Juan mine in New Mexico. Only the lower parts of the terraces 

 were seeded and irrigated. A section ot the irrigation pipe is shown in the foreground. The terraces not only concentrate 

 water but also reduce sheetwash erosion. July 1978. 



tion. Complete restoration per se, however, is 

 recognized as not being an achievable goal in 

 reclamation because it is technically imprac- 

 tical. The enormous complexity of dealing vi/ith 

 ecological systems can be illustrated by examin- 

 ing a soils map of a mining property (fig. 25). This 

 map shows the large number of different soils 

 that exist within a relatively small area. 



The use of original soil materials on newly 

 shaped mined lands, even if mixed during the 

 salvage process, generally has five major effects 

 on the revegetation potential, in comparison to 

 raw spoil materials. Original soil materials 

 (1) provide a seedbed with more desirable phys- 

 ical properties; (2) introduce more plant-available 

 nutrients; (3) act as a better medium to absorb 

 and hold moisture; (4) provide a source of native 

 seeds and native plants; and (5) provide bacteria, 

 algae, fungi, and other forms of soil flora and 

 fauna theoretically capable of reestablishing the 

 soil-forming process. 



TOPSOILING 



The reuse of the original soils as all or part of 

 the new growing medium in reclamation is call- 

 ed "topsoiling." The advantages of topsoiling for 

 the reestablishment of any form of vegetation 

 are now well recognized. Even thin topsoil layers 

 have proven advantageous where the spoil is 

 somewhat toxic. The optimal plant-growth rela- 

 tionship to topsoil thickness under economic 

 and supply constraints is being studied at many 

 surface coal mines (Deveraux, 1978, p. 200; and 

 Pole and others, 1979) (figs. 26 and 27). Topsoil 

 seems to be more important to long-term suc- 

 cess than various cultivational techniques which 

 are useful for improving the physical charac- 

 teristics and water-holding capacity of the grow- 

 ing medium. Spoil materials alone, however, 

 may be able to support a vegetative cover as pro- 

 ductive as that present before mining under the 



33 



