Bacterial diversity and functions in soils amended with biochar and organic fertilizers

dc.contributor.advisor Thomas, Torsten en_US Ye, Jun en_US 2022-03-22T13:26:47Z 2022-03-22T13:26:47Z 2016 en_US
dc.description.abstract Organic farming relies on the activities of bacterial communities for optimal soil productivity. Understanding the responses of bacterial communities to different soil amendments, including organic fertilizers and biochars, can provide information for soil management. This thesis firstly describes the bacterial diversity and functions that are central to soil processes of organic soils and their responses to fertilizers with different C/N ratios. Secondly, this thesis analyzes the effect of a mineral-enhanced biochar (MEB) on the bacterial community of organically amended soil. Finally, the thesis investigates the direct interactions between biochar and bacteria that underpin metabolic processes in the soil. Bacterial taxa that are resilient to different fertilizers were identified and defined as the core community of organic soil. The phyla Bacteroidetes and Planctomycetes, the family Cytophagaceae and the class Acidobacteria-5 were thus found in organic soil regardless of the type of fertilizer being applied. These core bacterial taxa were further linked to the functional potential of organic soil. The C/N ratio of fertilizer was also found to have a positive correlation with microbial N assimilation in organic soil. MEB was applied in combination with compost to soil and this resulted in synergistic effects on soil properties. Specifically, the soil nitrate content was increased, which correlated with an enrichment of bacterial nitrifiers due to the MEB addition. As a consequence, plants produced larger leaves, which demonstrates that MEB could be used to manipulate specific agricultural outcomes in organic farming. To understand the detailed mechanism that supports the beneficial effects of biochar and MEB, a novel method was developed to visualize the in situ interactions between bacteria and surfaces on a single-cell level. Distinct bacterial communities were found to exist on the surface of biochar and MEBs compared to surrounding soils and surface-associated bacteria were found to have the capacities to fix carbon dioxide using chemolithotrophic processes. This provides a bacterial mechanism on how biochar and MEBs can drive carbon sequestration into the soil environment. Together, the discoveries and models presented in this thesis provide new insights into the functions of soil microbiomes in organically amended soil. en_US
dc.language English
dc.language.iso EN en_US
dc.publisher UNSW, Sydney en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri en_US
dc.subject.other Scanning electron microscopy en_US
dc.subject.other Biochar en_US
dc.subject.other Biochar-mineral complex en_US
dc.subject.other in situ hybridization en_US
dc.subject.other organic farming en_US
dc.subject.other C/N en_US
dc.subject.other 16S rRNA en_US
dc.subject.other Metagenomics en_US
dc.title Bacterial diversity and functions in soils amended with biochar and organic fertilizers en_US
dc.type Thesis en_US
dcterms.accessRights open access
dcterms.rightsHolder Ye, Jun
dspace.entity.type Publication en_US
unsw.relation.faculty Science
unsw.relation.originalPublicationAffiliation Ye, Jun, Centre for Marine Biofouling & Bioinnovation, Faculty of Science, UNSW en_US
unsw.relation.originalPublicationAffiliation Thomas, Torsten, Centre for Marine Biofouling & Bioinnovation, Faculty of Science, UNSW en_US Centre for Marine Science and Innovation *
unsw.thesis.degreetype PhD Doctorate en_US
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