| This paper studied that in broadleaf forest on the limestone mountain of d ifferent closing years, soil microbes and their enzymes. In this paper, experiments in Qingyang County of Chizhou City in Anhui Province which divided the mountains into unclosing forests, closing 5 years,10 years,20 years and 30 years forests, were done to get soil samples and laboratory culture and analysis, the following conclusions:(1) By the physical properties experiments of soil samples found:soil structure destruction rate was 11.77% in closed forest, compared with the rate of 19.91% in unclosed forest which was 8.14% lower. With the increase of closing years, soil water content increased in broadleaf forest and water retention enhanced.This suggests that soil physical properties was significantly improved after closing, because of the decomposition of soil microorganisms, soil aeration enhanced and water holding was more favorable which conducived to the growth of plant roots.(2) By the chemical properties experiments of soil samples, the data show that:in broadleaf forest of closing 20years, at the depth of 0-0cm, organic matter, total N of soil was 25.43g/kg and 0.27g/kg higher than that in unclosing forest, available N、available P、available K ratio increased 139.18mg/kg、14.04mg/kg、14.28mg/kg than unclosing forest. This suggests that with the increase of closing years, coordination of water supply, soil chemical properties and soil fertility were improved which provided adequate nutrients to plant growth.(3) By microbial culture experiments in the laboratory, we found:The number of soil microorganisms in closing forest was higher than that in unclosing forest. Analysis of variance showed that the number of bacteria in the depth of 10-20 cm in closing forest was significantly higher than unclosing forest(p<0.05), in the depth of 20-30 cm in closing year of 30 was significantly higher than unclosing forest (p<0.05), other letters there was no significant difference (p> 0.05) between closing forests. This indicates that: closing measures can significantly increase the number of microorganisms in the soil which can help microbial growth and reproduction.(4) Through soil microbial biomass C, N experiments in the laboratory, we found: microbial biomass C in the depth of 0-10 cm in the closing year of 30, ranked the highest; microbial biomass N in the depth of 0-10 cm in the closing year of 30, ranked the highest; the content of microbial biomass C was higher in closing forest while the content of microbial biomass N was higher in unclosing forest; the content of microbial biomass C was highest in the depth of 0-10 cm in soil. This indicates that:the longer theyear of closing, the higher soil microbial biomass C, N content which can help the growth of microorganisms and the vertical distribution of soil microbial biomass presents certain regularity which decreased by the increase of soil depth.(5) In this paper, five kinds of microbial enzymes were done experiments of activity and we found that:with increase of closing year, soil enzyme activity was gradually increased, while soil enzyme activity gatherd more on the surface of the soil in closing forest and decreased by the increase of soil depth. Correlation analysis showed that in addition to the microbial and urease were not significant correlation, but with other enzymes showed a significant or very significant correlation; soil bacteria, fungi, actinomycetes, nitrogen and microbial catalase, dehydrogenase, sucrase, polyphenol oxidase activity were significant or very significant positive correlation; microbial carbon and catalase, dehydrogenase, invertase, polyphenol oxidase showed a significant negative correlation (p<0.05). This indicated that:soil microbial and activity influenced each other, and number of soil microorganisms and microbial biomass can indicate the soil enzyme activity at a certain degree. |
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