Pure culture and pot culture experiments were carried out to study the effect of lanthanum (La) on bacteria, actinomyces and fungus, and some microbial physiological groups , nitrifier, azotobacter and phos- phobacteria, in a red soil taken form the Ecological Experimental Station of Red Soil, the Chinese Academy of Sciences, Jiangxi Province. LaCl3 was added into media at levels of 0, 25, 50, 100, 150, 200, 250 and 500 mg L-1 in the pure culture experiment, and into soil samples in porcelain pots before rice growing at levels of 0, 6, 30, 150, 300, 600 and 900 mg kg-1 dry soil in the pot culture experiment. The populations of the three soil microbes in the pure culture experiment decreased with the addition level of La, indicating that La was toxic to the soil microbes in pure culture, and the sensitivity of the 3 major microbial types to La was in a decreasing order of actinomyces > bacteria > fungus. In the pot experiment, La had slightly stimulative effect on soil bacteria and actinomyces when applied at low concentrations while had inhibitory effect on soil bacteria, actinomyces and fungus at high concentrations. When the concentration of La was low, soil azotobacter was stimulated slightly while soil nitrifier was stimulated strongly and the maximum increase was up to 50%. When the concentration of La was high, both soil azotobacter and nitrifier were inhibited, and the inhibition of La to the nitrifier increased with La concentration. La added at all the levels had stimulative effect on soil inorganic and organic phosphobatteria. Among the 4 physiological groups, soil nitrifier was most sensitive to La, so , it might be reasonable to assume that soil nitrifier was a sensitive indicator for evaluating the biological and environmental effects of rare earths.
展开▼
机译：Pure culture and pot culture experiments were carried out to study theeffect of lanthanum (La) on bacteria, actinomyces and fungus, and somemicrobial physiological groups, nitrifier, azotobacter andphosphobacteria, in a red soil taken form the Ecological ExperimentalStation of Red Soil, the Chinese Academy of Sciences, Jiangxi Province.LaCl{3 was added into media at levels of 0, 25, 50, 100, 150,200, 250 and 500 mg L-1 in the pure culture experiment, and intosoil samples in porcelain pots before rice growing at levels of 0, 6,30, 150, 300, 600 and 900 mg kg-1 dry soil in the pot cultureexperiment. Thepopulations of the three soil microbes in the pure culture experimentdecreased with the addition level of La, indicating that La was toxicto the soil microbes in pure culture, and the sensitivity of the 3major microbial types to La was in a decreasing order ofactinomyces > bacteria > fungus. In the pot experiment, Lahad slightly stimulative effect on soil bacteria and actinomyces whenapplied at low concentrations while had inhibitory effect on soilbacteria, actinomyces and fungus at high concentrations. When theconcentration of La was low, soil azotobacter was stimulated slightlywhile soil nitrifier was stimulated strongly and the maximum increasewas up to 50%. When the concentration of La was high, both soilazotobacter and nitrifier were inhibited, and the inhibition of La tothe nitrifier increased with La concentration. La added at all thelevels had stimulative effect on soil inorganic and organicphosphobacteria. Among the 4 physiological groups, soil nitrifier wasmost sensitive to La, so, it might be reasonable to assume that soilnitrifier was a sensitive indicator for evaluating the biological andenvironmental effects of rare earths.
展开▼
