| Presently there is little research on the effect of water and soil conservation using microbiological methods at home and abroad,so in this experiment the research on the effect of different water and soil conservation measures in different seasons on microbial diversity and their number was used to estimate the soil conditions under different water and soil conservation measures and thus the effect of the water and soil conservation measures was reflected from the aspect of microbes and the measures fit for popularization were selected,which could provide some theoretical basis for the further research and popularization of water and soil conservation measures and green bio-fertilizer and fertilizer management method.Besides,it could also provide some data for reference for the scientific management of wood soil,orchard soil and tea garden soil in the hilly area.In this thesis,selected the microbial extraction method which used in the methods of traditional culture by orthogonal experiment at first,and then combined physiology and molecular biology to research the effect of the six water and soil conservation measures(the district with grass covered in the whole orchard,up and down slope cleaning tillage district,terrace ? district,terrace ? district,terrace cleaning tillage district,strip covering and mulching)in different seasons on the number of soil microbes and their diversity and the results were as follows:(1)The methods of traditional culture:it was adopted to research the effect of different water and soil conservation measures in different seasons on the number of the top three soil microbes.Through the experiment,the bacteria extraction conditions was as follows:scillation speed of 150 r/min,oscillation time of 30 min,sodium cholate with the concentration of 1.0%.The actinomycetes extraction conditions was as follows:scillation speed of 200 r/min,oscillation time of 30 min,sodium pyrophosphate with the concentration of 0.2%.The fungi extraction conditions was as follows:scillation speed of 200 r/min,oscillation time of 30 min,sodium cholate with the concentration of 1.0%.It was showed that on the whole,tthe number of bacteria and actinomycetes was:summer>autumn>spring>winter,and the number of fungi was:spring>winter>autumn>summer.The number of microbes changed with the change of seasons.The change of the number of bacteria and actinomycetes was consistent with that of the temperature while fungi was quite the opposite.The change of the number of bacteria,actinomycetes and fungi and the change of the ratio of fungi to bacteria in different districts were consistent and the order by microbial number was:terrace ? district>terrace ? district>strip covering and mulching district>the district with grass covered in the whole orchard>up and down slope cleaning tillage district>terrace cleaning tillage district.It was showed that both the number of microbes and the system stability in terrace ? district were higher than those in the other districts.(2)The method of physiology(Biolog eco):it was adopted to the research on the effect of different water and soil conservation measures in different seasons on microbial functional diversity.The detailed results were as follows:? As for the microbes from various districts in various months,within 7 days all the average color change rates increased and the increase rate was fast at first and slow later.On the whole,the trend of AWCD(Average Well colour Development)value was:terrace ? district>terrace ? district>strip covering and mulching district>the district with grass covered in the whole orchard>terrace cleaning tillage district>up and down slope cleaning tillage district,summer>autumn>spring>winter.It was showed that the physiological activity and the metabolic capacity of soil microbes presented the rule above and had close relationship with the change of temperature.The utilization efficiency of the top six carbon sources in various districts in various months also represented this rule and the ability of microbes to utilize carbon sources in different seasons was:summer>autumn,autumn>spring,spring>winter.The utilization efficiency of carbohydrate and polymer in various areas was the highest in April while the utilization efficiency of carbohydrate and amino acid in various areas was the highest in January,July and October.The utilization efficiency of aromatic compound was the lowest.The utilization efficiency of polymer and aromatic compound in various areas was the lowest in January and April.The utilization efficiency of Carboxylic acids and aromatic compound in various areas was the lowest in July and October.? Through the comprehensive analysis on various indices in different districts and different seasons,it was known that:Mclntosh index,namely the homogeneity of communities in an area,was obviously different in different areas and the homogeneity of communities in terrace ? district was the best while it was the worst in up and down slope cleaning tillage district.Shannon index,namely the diversity of communities in an area,was also obviously different in different areas and the order was:terrace ? district>terrace ? district>strip covering and mulching district>the district with grass covered in the whole orchard>terrace cleaning tillage district>up and down slope cleaning tillage district.Simpson index,namely the dominance of communities in an area,had no evident difference in different areas and different months.? Through the analysis on the main components of Biolog,it was further known that the species of carbon sources utilized by microbes and the utilization efficiency in various districts was:July(summer)>October(autumn)>April(spring)>January(winter).In July,the distribution of various carbon sources was comparatively concentrated compared with that in the other months,which showed that the utilization efficiency of various carbon sources was better in various districts in July(summer),while the utilization efficiency of various carbon sources was worse in various districts in January(winter).Through analysis on the carbon sources which had greater contribution to the two main components in every month,it was known that there were differences in the utilization of carbon sources by soil microbial communities in the districts with different measures in different seasons.The comprehensive analysis was showed that dfferent water and soil conservation measures in different seasons had a great impact on soil microbial functional diversity.(3)Biochemical method(PLFA):Through the research on the content and species of the characteristic fatty acid by the method of PLFA,the effect of different water and soil conservation measures in different seasons on the diversity of the structures of microbes was researched and the detailed results were as follows:? According to the categories of microbes and their content,fatty acid content in various months had the follow-ing sequence:the characteristic fatty acid content of bacteria and actinomycetes:July(summer)>April(spring)>October(autumn)>January(winter);the characteristic fatty acid content of fungi:April(spring)>January(winter)>October(autumn)>July(summer),which was the same with the result by the traditional culture method.lt could be seen that seasons had the same effect on bacteria and actino-mycetes while the effect of seasons on fungi was obviously different from that on bacteria and actinomycetes.Through analysis on the change charts of the content of fatty acid in various months,it was known that the order of the content of fatty acid was:terrace ? district>terrace ? district>strip covering and mulching district>the district with grass covered in the whole orchard>terrace cleaning tillage district>up and down slope cleaning tillage district,and according to the classifications of microbes(bacteria,actinomycetes,fungi),the order of PLFAs was::terrace ? district>terrace I district>strip cover-ing and mulching district>the district with grass covered in the whole orchard>terrace cleaning tillage district>up and down slope cleaning tillage district,namely,bacteria,fungi and actinomycetes had the same order.Besideas in July the content of the characteristic fatty acid of actinomycetes was higher than that of fungi;in the other months the content of the characteristic fatty acid was:bacteria>fungi>actinomycetes.? Through comprehensive analysis on the diversity index of PFLA in various districts and various months,it was showed that the order of Shannon index in various districts was:July(summer)>October(autumn)>April(spring)>January(winter)and terrace ? district>terrace ? district>the district with grass covered in the whole orchard>strip covering and mulching district>terrace cleaning tillage district>up and down slope cleaning tillage district It was showed that the climate in the corresponding seasons had certain effect on the diversity of the microbial structures.Different water and soil conservation measures in the same season had greater effect on the diversity of the microbial structures.? Through analysis on the main components of PLFA in various months,it was known that:bacteria had greater effect on the two main components.Besides,actinomycetes had greater effect on the main component 1 in January while fungi had greater effect on it in April and October and actinomycetes and fungi had greater effect on it in July.lt was showed that various microbes were active in July.Bacteria and fungi had greater effect on the main component 2.It was showed that the two.principal components were the representative factors of the correspond-ing characteristical fatty acids respectively.And thus it was known that bacteria had greater effect on the two components and fungi came next.The effect of fungi exceeded actinomycetes which accorded with the following objective condition:red soil is suitable for the growth of fungi.(4)Through comprehensive analysis on Biolog and PLFA cluster analysis,it was known that the results of cluster analysis by the two methods were basically consistent and both the results showed that the difference between the district with grass and the cleaning tillage district was obvious and the difference between terrace district and up and down slope district was obvious.The difference between terrace district and the cleaning tillage district was the most obvious.The detailed classification was:terrace ? district and terrace ? district could be classified as a category;strip covering and mulching district and the district with grass covered in the whole orchard could be classified as a category;terrace cleaning tillage district and up and down slope cleaning tillage district could be classified as a category.Sometimes,both terrace ? district and up and down slope cleaning tillage district could be classified separately.In conclusion,the methods of traditional culture,physiology and molecular biology comprehensively showed that different water and soil conservation measures had great effect on the number and the diversity of microbes and the research results by these three methods were basically consistent in different seasons.Through comparison with the relevant documents referring to the research of the physicochemical property of water ans soil conserva-tion,the result of this research was generally consistent with the result of the research on physicochemical property and they both represented the following results:up and down slope cleaning tillage district was the worst in every aspect;terrace ? district was superior to the other districts in various aspects;from the aspect of biochemistry,the research showed that the effect of water and soil conservation in terrace ? district was the best among all the districts. |
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