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The Effects Of Soil Organic Carbon(SOC) And Its Compositions On Soil Bacteria And Micro-Ecological Properties

Posted on:2016-03-17Degree:MasterType:Thesis
Country:ChinaCandidate:H X WanFull Text:PDF
GTID:2370330473466888Subject:Plant pathology
Abstract/Summary:PDF Full Text Request
Soil as the material basis for the plant growth and development,the soil health is one of the important basis of plant healthy growth,and higher enzyme activity and soil microbial diversity are important basis of soil health.Cultivation and management measures unreasonable about tobacco results in rampant of plant diseases and insect pests,decline soil available of fertility,reducing disease-resistance,decline tobacco yield,reducing quality and sustainable production ability and many other problems.All of this has become a prominent problem about tobacco leaf production in China.Therefore,to find a new technology and new method which is not depend on the chemical control and crop rotation to control soil-borne diseases of tobacco,and looking for influence machine of soil microecological balance is imminent.This experiment analyzed the change of the content of soil total organic carbon and its components,and the change of microbe quantity about previous soybean,sweet potato,pepper,and 2 years,3 years,4 years,5 years,7 years of continuous cropping eight samples in Henan Yiyang tobacco field.Determined the components of organic carbon of different continuous cropping years,based on which to design the different influence of the components of organic carbon,such as total organic carbon(TOC),dissolved organic carbon(DOC),salt dissolved organic carbon(SDOC),soil microbial biomass carbon(SMBC),light group of organic carbon(LFOC)and particulate organic carbon(POC)on the growth of different soil bacteria in vitro culture.And then based on the test results of two previous analysis,the activity of DOC is highest,respectively designed Low,medium and high content of DOC,and analysis soil enzyme activity,microbial diversity and SMBC in different culture time.Preliminary clear the mechanism of the influence of SOC to soil health,in the end using pot experiment method preliminary demonstrated DOC and POC effects on tobacco.The main results were as follows:(1)The trend of soil organic carbon components of continuous cropping years: previous soybean > previous sweet potato > previous pepper > 2 years continuous cropping > 3 years continuous cropping > 4 years continuous cropping > 5 years continuous cropping >7 years continuous cropping.The content of TOC,POC,LFOC,DOC and SDOC each between 15.86-10.17g/kg?10.6-5.21 g/kg?10.51-4.71 g/kg?1.26-0.4 g/kg?1.2-0.48 g/kg,as the extension of continuous cropping years showed a trend of decline.POC/TOC,LFOC/TOC,DOC/TOC and SDOC/TOC between 66.83-41.98?66.27-44.3?8.54-3.93?7.57-4.43(%),POC/TOC,LFOC/TOC are higher than DOC/TOC,SDOC/TOC.TOC and DOC,POC and LFOC,DOC and DSOC had a highly positive correlation,the correlation coefficient(R)were greater than 0.900(table 2),correlation coefficient R between TOC and DOC was maximum,TOC and DOC compared to other components of SOC had the closest relationship.Results showed that the organic carbon and its components were contained in each other,promoted each other,and under certain conditions can be converted to one another.(2)The number of bacteria and SMBC along with the extension of continuous cropping had a declining trend,were extremely significant differences between each data of 8 soil samples;From the correlation analysis of SMOC,bacteria number,and other organic carbon components can be derived,DOC,TOC and SMBC,bacteria reached extremely significant correlation,SDOC and SMBC reached extremely significant correlation,SDOC and bacteria number reached significant correlation.The correlation of POC,LFOC and SMBC and bacteria number are less than TOC and DOC,SDOC.The results suggested that: though the quantity of DOC was little,the impact on bacterial diversity was higher than POC and LFOC.(3)From the test that the different influence of the components of organic carbon on the growth of different soil bacteria in vitro culture,can be concluded that adding different organic carbon composition and quantity,bacteria developed at different rates.DOC had the greater influence on the bacterial growth,prophase of cultivation increased rapidly and anaphasis relatively slow;secondly is POC,bacterial growth was relatively lagging than DOC,and LFOC had the least influence on the bacterial growth.This may be due to the DOC solubles in water,was easily absorbed,utilized and transformed by bacteria and plants than POC ? LFOC.But Ralstonia solanacearum and gram-negative bacteria significantly increased in high concentrations of POC.In addition,bacteria growed faster in the rich medium than the poor medium,the ratio of R.solanacearum to mixed bacteria declined over time.(4)In the soil environment,the amount of DOC had a different influence on soil bacteria,SMOC and enzyme activity.Total bacteria,R.solanacearum quantity and SMOC increased over time and with the increase of DOC.Total bacteria,SMOC,invertase activity,amylase activity and cellulose activity were showed a high positive linear correlation,and invertase activity had the closed relationship with total bacteria and SMOC of the three enzyme.Results showed that microorganism amount,SMOC and enzyme activity promoted and depended on each other.(5)The pot experiment showed that DOC can obviously promoted the growth of tobacco than POC,the more DOC or POC increased,the better tobacco growed than CK.
Keywords/Search Tags:tobacco, cultivation and management, soil health, soil organic carbon and its components, soil microbial diversity, soil enzyme activity
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