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Effects Of Biochar On Soil Enzyme Activities And Bacterial Diversities In Semi-arid Region

Posted on:2020-08-01Degree:MasterType:Thesis
Country:ChinaCandidate:Y WangFull Text:PDF
GTID:2370330596972672Subject:Environmental Science
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Soil erosion in the semi-arid region of the Loess Plateau is serious.Problems such as soil water shortage,low soil fertility,and serious soil erosion have led to the fragile ecological environment of the area,which has also restricted the development of agriculture.As an effective way to increase moisture holding capacity,enhance soil fertility and improve soil quality,biochar can be used to alleviate the drought and infertility in semi-arid areas.With surface soils of Guyuan Ecological Experiment Station in Semi-arid Region restored by biochar for 4 years being the research objects,the long-term response of two types of biochar?locust tree bark biochar?sawdust biochar?at three different mass percentages?1%,3%and 5%?on soil physical and chemical properties,enzyme activities?urease,Invertase,alkaline phosphatase?and microbial biomass were analyzed.Meanwhile,soil bacterial community diversity and community were investigated by using Miseq high-throughput sequencing technology,the relationship between physicochemical factors and soil enzyme activities,bacterial community structure were discussed by using redundant analysis.The main results are as follows:?1?In 0-20cm soil layer,the content of soil organic carbon,available phosphorus and ammonium nitrogen increased significantly by 42.16%-237.69%?22.21%-331.60%and103%-497%respectively after the application of biochar for 4 years.The content of total soil nitrogen increased by 0.82%-50.34%.There is no obvious effect on the content of nitrate nitrogen,but 3%mass percentage of biochar has the greatest impact on nitrate nitrogen content.The content of organic carbon and total nitrogen increased with the increase of the dosage of biochar.In general,the positive effect of locust tree bark biochar on soil physicochemical properties is better than sawdust biochar,and the best application mass percentages is 5%.?2?There are differences in the effect of biochar application on soil enzyme activity and microbial biomass for 4 years,but it has not reached a significant level.Soil urease activity and soil microbial biomass carbon content discreased with two types of biochar addition,and alkaline phosphatase activity and microbial biomass nitrogen content increased by 0-28.63%and 33.74%-135.76%,respectively.Invertase activity was related to the type of biochar,the positive effect of sawdust biocharon soil enzyme activity is better than locust tree bark biochar.Soil urease,sucrase,alkaline phosphatase activity,microbial biomass carbon and microbial biomass nitrogen decreased with soil depth.The correlation between physicochemical factors and soil enzyme activity,microbial biomass in different soil layers was not completely consistent.Urease was significantly correlated with available phosphorus,organic carbon and total nitrogen.Microbial biomass nitrogen was significantly correlated with available phosphorus,and sucrase was significantly correlated with nitrate nitrogen.?3?The diversity of soil bacterial community was increased with biochar addition,and the diversities were higher in the sawdust biochar treatment than in the locust tree bark biochar treatment.Further,3%sawdust biochar addition had the best effect on bacterial community diversities,and its Shannon index was 6.22.The dominant taxa at phyla level were Actinobacteria,Proteobacteria,Chloroflexi,Acidobacteria and Saccharibacteria,with relative abundance of 76.80%85.31%.The dominant taxa at class level were Actinobacteria,Alphaproteobacteria,Acidobacteria,with relative abundance of48.13%57.08%.At genus level,the relative abundance of the Bacillus,Nitrospira increased,while the relative abundance of the Pedomicrobium,Rhizobium decreased after being added biochar.Hierarchical clustering and redundancy analysis?RDA?indicated that the application of biochar greatly affected the bacteria community structures.The microbial biomass carbon,water content,ammonium nitrogen?NH4+-N?,organic carbon contents had great influence on the variations of bacterial community structure.The heatmap of the correlation between taxa of dominant bacteria and environmental factors further indicated that NH4+-N concentration was significantly correlated with Actinobacteria and Chloroflexi.Therefore,the change of NH4+-N caused by biochar addition was the key factor leading to the variations of soil bacterial communities.
Keywords/Search Tags:Biochar, Physical and chemical properties, Enzyme activity, soil bacteria, diversity
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