Amendment of Mine Spoil to Increase the Number and Activity of Microorganisms
1984
Lindemann, W. C. | Lindsey, D. L. | Fresquez, P. R.
If mine spoil areas are not topsoiled in spoil reclamation, microbial numbers and activities may need stimulation. The objectives of this study were to determine the effect of spoil amendment on microbial parameters and mycorrhizal infection of grass species in the field. Spoil on the San Juan coal mine near Farmington, New Mexico was amended with hay, sludge, or topsoil inoculum, or was covered with 30 cm of topsoil as normally practiced. Microbial parameters measured in both the rhizosphere and nonrhizosphere included numbers of bacteria, Streptomyces, ammonium oxidizers, Azotobacter, dehydrogenase enzyme activity and fungal genera distribution. Mycorrhizal inoculum (roots and soil containing Glomus mosseae and G. fasciculatum) was also applied and plants were examined for percentage mycorrhizal roots. The addition of either sludge or hay or topsoiling increased the number of microorganisms, enzyme activity and fungal genera distribution in nonrhizosphere spoil. Topsoil added as an inoculum had little or no effect on these biological factors. Only the number of Azotobacter was significantly increased in the rhizosphere by spoil amendment. Providing an available carbon source was more critical in stimulating an active and varied microflora than was a topsoil inoculum. Mycorrhizal infection was poor in all treatments. Amendments had no or little effect on percentage mycorrhizal roots. Covering the spoil with 30 cm of topsoil provided the greatest amount of mycorrhizal infection.
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