Study Of Soil Microbial Community Structure And Activity About Main Rubber Konjak In Our Country

Large-scale planting the rubber has started in China since 1951. At the beginning, the rubber plantations were reclaimed by the original forest and secondary rainforest, and the soil fertility and the structure were in a high level. But the soil fertility has declined quickly after planting the rubber a few years. In this study, the research object was the soil of the main rubber plantations of Hainan, Yunnan, and Guangdong provinces.This paper has determined the physical,chemical and microbiology indicators of the soil. Previous researches show that the soil quality assessment system generally includes soil physical, chemical and biological characteristics. But most of the studies emphasize the soil physicochemical properties to be the evaluation index of soil quality and fertility, and the biological components which really play a key role were often neglected. So it has a great potential to select some soil microbiology parameters as the evaluation index of soil quality.To compare with the soil physics and chemistry. index, the biology index of the quality and fertility of soil evaluation possessed many biological characteristics, such as sensibility, comprehensiveness, functionality and so on. Comparing the soil of rubber plantation with the soil of farmland ecosystem, its disturbance of the human activity is smaller. Thus the stability of the rubber plantation soil ecosystem must be higher than the farmland ecosystem's. Therefore, when it comes to the sensitive microbiology index, the ecosystem quality or the fertility appraisal of the rubber plantation are more meaningful than the farmland ecosystem's.According to the front literatures, this paper selected the following microbiology index: microbial biomass, biodiversity, soil respiration and derivation index, microbial community structure and function, soil enzyme and so on.Firstly, determine the main physics and chemistry index of the rubber plantation soil, which mainly covers organic matter, total nitrogen, available phosphorus, available potassium as well as pH value. And then, the microbiology index was determined. We have separately analyzed the correlations between microbiology indexes and physics and chemistry indexes.We observed whether or not it had strong correlations between the microbiology indexes and physicochemical indexes. If there were good correlations, what the level of correlative dependence is. And study from these indexes that which are the immediate influences, which are the indirect influences. By these we can draw the conclusion that which microbiology index can be used to appraise the fertility and quality of the rubber plantation soil, and the conclusion will employ certain instruction function to the rubber plantation soil's fertilization.By determining various rubber plantations soil's foundation physics and chemistry properties in the main production area, the data indicated that, rubber plantation soil's fertility is generally in a medium level, even a below level. Comparing the contents of rubber plantation soil organic matter and the total nitrogen with 1954, both of the levels have dropped. Among the various indexes of microbiology, the variation coefficient of bacterium is low, and the variation coefficient of fungus is high. The variation coefficient of microbial biomass carbon and the microbial biomass nitrogen as well as the respiratory entropy are quite high. The coefficient variation of microbial entropy, dehydrogenase,acid phosphatase and urease are little low.The change of various soil microorganisms indexes are big in different rubber production area of our country, and the level of fertility existence are different, too.By analysing the correlation between various microbiology indicators and physics and chemistry indexes, we found that only among microbial biomass carbon, microbial entropy and respiratory entropy it exist the significant level of correlation coefficient. And among other microbiology activity indexes, the correlation coefficients are low, and the level of correlations can't reach a significant level.According to the relevance among various indexes, take the microbial biomass carbon, microbial entropy and metabolism quotient as a dependent variable, take other indexes which are remarkable related to organic matter as the dependent variable, and make the multivariate linear regression analysis. We draw the multi-dimensional linear regression model and extrapolated that the predicted value of these indexes are effective, P=0<0.05 (a=0.05 is a significant level, the value of P is less than a). The fitting degree of these three linear regression models is very high.The linear regression equation of microbial biomass carbon expressed that the model which was obtained by the microbial entropy and the organic matter as well as metabolism business could explain the changeability of 98.6% microbial biomass carbon. Among these, the changeability influence quantity of the microbial entropy to the microbial biomass carbon is 0.913 unit quantity. The changeability influence quantity of the organic matter to the microbial biomass carbon is 0.395 unit quantity. And the changeability influence quantity of metabolism entropy to the microbial biomass carbon is 0.073 unit quantity.The linear regression equation of the microbial entropy expressed that the model which was obtained by the microbial biomass carbon and the organic matter was possible to explain the changeability of 98.5% microbial entropy. Among these, the microbial biomass carbon influences the microbial entropy's changeability forâ… .003 unit quantity, and organic matter influences the microbial entropy's changeability for-0.412 unit quantity.The linear regression equation of the metabolism quotient expressed that the model obtained by the microbial entropy and the microbial biomass carbon is possible to explain the changeability of 85.6% metabolism quotient. Among these, microbial entropy influences metabolism quotient's changeability for-0.480 unit quantity, and microbial biomass carbon influences metabolism business's changeability for-0.468 unit quantity.Finally, we can draw the conclusion that:the microbial biomass carbon and the microbial entropy as well as metabolism quotient can be taken as the sensitive index to appraise our country rubber plantation.