Effect Of Sewage Sludge Compost On Physio-chemical And Bioloical Charateristics Of Imazethapyr-contaminated Soil

Application of organic fertilizer can alter physic-chemical characteristics and especially structure of microbial community of soil,thereby accelerating the degradation of imazethapyr and promoting the remediation of the contaminated soil.However,the lack of knowledge in the physic-chemical characteristics and microbial community structure in soil influenced by application of organic fertilizer,especially sewage sludge compost,usually impede the development of bio-remediation technique.In the present research,a pot experiment was conducted to investigate the impact of application of sewage sludge compost(0%,2%,4%,8%)on the physic-chemical characteristics and microbial community structure in imazethapyr-contaminated soil,to provide theoretical and technical support for agricultural utilization of sewage sludge compost and bio-remediation of contaminated soil.The main results are as follows:1.With the increase of application rate of sewage sludge compost,pH value,total nitrogen,nitrate nitrogen,total phosphorus,available phosphorus,total potassium,available potassium and organic matter content increased,and the degrading rate of imazethapyr also increased,indicating that application of sewage sludge compost is beneficial to soil fertility and bio-remediation of contaminated soil.2.Soil enzyme activity increased with the increase of sludge compost application rate.Soil microbial biomass carbon and nitrogen was the highest with the compost application rate of 4%,and decreased with the further increase of the fertilizer.3.The soil enzyme activities and physicochemical factors and imazethapyr degradation rate by correlation analysis,results showed that,enzyme activities and physicochemical factors and imazethapyr degradation rate showed a good correlation,it showed that the enzyme activity can express not only the soil fertility status also characterize soil pollution.4.Contents of heavy metals in 4 soils and in crop seeds also increased with the increase of fertilizer,but are in a safe range,when the quantity of fertilizer was 8%when the Cd content in the soil exceed the standard,while Cd and Pd exceed the standard of grain crops,but according to the single factor pollution evaluation of heavy metals,heavy metals,the rate of increase is not great,this application shows that,a quarter of the tested sludge compost will not affect the soil and soybean safety quality edible,but long-term application of sewage sludge compost will cause the soil heavy metal accumulation remains to be further studied.5.Using PCR-DGGE technology of sludge compost effects of pollution,the results show that soil microbial diversity,richness of microbial communities in soil composting of sewage sludge and diversity index were higher than that of control soil,with the increase of soil microbial richness and diversity index increased first and then reduce the phenomenon of sewage sludge compost fertilizer.When the dosage was 4%,the bacterial richness and diversity index reached the highest,with the further increase of compost decreased.6.Sludge compost application changes the pollution soil microbial community structure,soil in this experiment detected in four bacteria were Gram negative bacteria,Actinobacteri,Bacteroidetes and Unclassified bacteria.Bacteroides were distributed in all samples,can be seen as the native soil bacterium.Actinomycetes only in the compost treated soils was detected,showed that the application of sludge compost changed the soil bacterial community composition.The sequencing results showed:fungi Ascomycetes as the major fungal taxa,Basidiomycetes times,they were in all the soil samples,generally speaking,fertilization did not change the soil fungal population types,only to change the distribution of fungi in soil.