Effect Of Rare Earth On Microbe Flora In Yellow Cinnamon Soil

The rare earth elements belong to B Group TuB in the periodic table of chemical elements. The rare earth elements (REE) have been applied in agriculture for more than twenty years in china. With the increasing applications of REE, people pay more and more attentions to the environmental influence of REE. In this paper, the effects of different accumulations of REE on the quantity of major groups and major physiological groups of soil microorganisms were researched and the reference data for the safe applications of REE in agriculture were offered in ecological view. The quantity of the REE seasonally used in the fields was simulated, the REE was dripped in basin earth in the lab everyday and the quantity of microorganisms in the soil was checked regularly. The accumulations of REE had obvious effected on the total number of bacteria in soil. The total number of bacteria was restrained when the REF was below 70mg/kg. The total number of bacteria tended to increase when the REE was from 80mg/kg to 150 mg/kg. The REE accumulation below 100mg/kg could stimulate the growth of actinomycetes and the ti.al population increased by 10-10%. The number of actinomycetes fluctuated in small range when the REE was accumulated above lOOmg/kg.The 50 mg/kg REF affected the germination of spores and the diameters of clones were smaller than that of the control groups. The REF stimulated the growth of fungi, the total population of fungi was larger than that of the control groups. The REF accumulation between 100mg/kg and 200 mg/kg stimulated the germination of spores of fungi.. The REE between 300 and 500 mg/kg could improve the product of soluble pigment of penicilluni purpurogenum which was harmful to the crops. With the accumulation of the REE, the ratios of number of resistant microbe to total population were higher than that of the control groups. It proved that the accumulation of the REE had affected the composition of groups of microorganisms. The REF below 60mg/kg had the most obviously inhibitory effects on ammonifiers bacteria and the population of ammonifiers bacteria was 21--.80% less than that of the control groups. The population of ammonifiers bacteria slightly increased when the REF was accumulated from 60 mg/kg to 200 mg/kg. As a whole, the REE had strong inhibitory effects on ammonifiers bacteria. The REE below 80mg/kg stimulated the growth of cellulose-decomposing bacteria, the total population of cellulose-decomposing bacteria increased doubly. When the REF were accumulated above 90 mg/kg, the total population of cellulose-decomposing bacteria descended. The REF from 2 mg/kg to 70 mg/kg stimulated nitrifying bacteria and made the population increase. The population of nitrifying bacteria slightly decreased when the REF was above 90 mg/kg, The REF also made the composition of clones of nitrifying bacteria change. When the REF over 150mg/kg, the Nitrosomonas Winogradsky becomes the dominant genus and its total population was 8 times of control. The REF inhibited the growth of azotobacter at first and then improve the growth of azotobacter . The critical point was at 70mg/kg. Below this point, the population of azotobacter decreased; above this point, the REF made the quantity of azotobacter increased rapidly and the quantity reached the peak at 110mg/kg. In the samples selected from Fei-dong sub-district, the REF below 0.27mg/kg stimulate the growth of bacteria and actinomycetes,...