Biochar as a soil amendment and habitat for microorganisms

[Truncated] This research sought to determine the role of biochar as a soil amendment and potential habitat for soil microorganisms, incorporating the use of high resolution microscopy techniques and determining the subsequent interaction of biochars with several soils, soil amendments (organic matter and P fertiliser) and their effects on soil microbial properties and plant growth. Biochar as a habitat has been suggested as one of the mechanisms which may help promote the microbial status of soil, including activity of arbuscular mycorrhizas. Procedures for observation and quantification of the habitat preferences on biochar were based on use of various microscopy imaging techniques (Chapter 3). Micrographs obtained from scannning electron microscopy (SEM) were used to characterise morphological characteristics of biochars. Woody biochars are potential habitat for soil microorganisms due to their high porosity and wide range of pore size based on pore distribution in microscopic images. SEM observations demonstrated differences in pore and surface properties of the biochar. Biochar particles were compared in soilless media and after deposition in soil. Fungal staining with fluorescent stains and preparation techniques for preserving and preparing biochar and/or biochar colonised by fungi were studied with both fluorescence and electron microscopy to determine the nature of fungal colonisation in or on biochar surfaces and pores in both soilless and soil systems. Biochar retrieved from soil and observed using fluorescence microscopy exhibited distinct hyphal networks on external biochar surfaces. The hyphal colonisation of biochar incubated in soil was much less than for biochar artificially inoculated with fungi in soilless medium.