- Title
- An analysis of the impacts of biochar to disturbed soils from the Hunter Valley, New South Wales
- Creator
- Regan, Andrew Thomas
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2016
- Description
- Masters Research - Master of Philosophy (MPhil)
- Description
- Currently, there are approximately 20,000 ha of land that requires rehabilitation in the Hunter Valley, New South Wales. The revegetation of these lands is vital to achieving acceptable environmental outcomes for the affected local communities. Revegetation success is limited, however by the poor quality of soils following disturbance. The soil removal and storage process results in reduced water holding capacity, nutrient retention and physical structure. Organic amendments are commonly used to improve the quality of soils and therefore the outcomes of mine rehabilitation. Biochar is an organic amendment that has not been extensively tested on disturbed soils from the Hunter Valley. Biochar is a relatively recent discovery, with many studies finding its effectiveness to vary based on its production conditions and the existing properties of the receiving soil. Biochar is hypothesised to improve a range of soil physical, chemical and biological properties resulting in improvements to plant growth. The impact of biochar on soils can depend on the biochar properties and receiving soil properties. The varied response of plants and soils to biochars suggests that not all soils will benefit from applications of biochar. The potential for negative responses to biochar and irreversibility of application in a field environment leads to the conclusion that biochars must be adequately tested in a controlled environment before field testing and eventual wide-scale use. With this in mind, a number of experiments were undertaken to determine the impact of plant-derived biochars on disturbed soils from the Bengalla Mine in the Hunter Valley. These experiments included: A baseline soil and biochar characterisation to identify the likely interactions that would take place between the soils and biochars. ; A series of pot plant trials in a glasshouse environment to quantify the interaction between soil and biochar and the plant response to different combinations of soil and biochar. ; Total and matric soil suction tests to determine the impact of biochar on soil water retention. ; Column leaching experiments to elucidate the impact of biochar on soil permeability and water retention. The soil baseline analysis identified Biochar One would have a positive impact on the Bengalla Silty Clay Loam. This was based on the low soil pH and high biochar pH, low soil carbon content and high biochar carbon content, and other properties. Pot Trial One and Pot Trial Two analysed the response of the Bengalla Silty Clay Loam to Biochar One. The results found biochar significantly reduced soil bulk density, improved moisture content, pH, soil carbon, and increased soil nutrient retention from fertiliser. These improvements correlated with a significant increase in seedling germination, plant height and plant yield. The baseline analysis could not determine if Biochar Two would have a positive or negative impact on the Bengalla Light Clay. Pot Trial Three analysed the plant response of the Bengalla Light Clay and Biochar Two. Soil testing found biochar significantly improved some soil properties, but this was not evidenced in the plant growth results. The plant growth increased when biochar was applied at 20 t/ha but trended negatively with increasing biochar application rates. Further testing in the form of total and matric soil suction tests and column leaching experiments were undertaken to elucidate the physical interactions between the two materials. The total and matric soil suction tests found slight reductions in soil suction when applied with biochar, and biochar in isolation (100% biochar) contained significantly less moisture at all suction values. Therefore the negative plant response in the higher biochar application rates in Pot Trial Three can partly be explained by limited water availability. The column leaching experiment was undertaken to assess the impact of biochar on soil permeability. Saturated hydraulic conductivity was higher under the 100 t/ha treatment, which was considered a benefit given the extremely low saturated hydraulic conductivity of the control. The impact of biochar to leachate quality was low, therefore addressing the concern that it may negatively affect downstream water reserves when applied in the field. Overall, the study found biochar significantly improved properties of disturbed soils, however the resulting impact on plant growth was inconsistent. The analysis of soil and biochar characteristics prior to application is highly recommended to determine the likelihood of a positive response and ensure the biochar addresses the limitations of receiving soils. The use of pot trials to further confirm the plant response to soil and biochar combinations is recommended prior to field testing or wide-scale uptake of biochar technology. Careful consideration of reported biochar results is recommended due to the variation in pot trial methodologies. This study identified that the study of biochar and other solid soil amendments lack a formally recognised and standardised pot trial methodology. The pot trial methodologies in this thesis were based on published journal articles and therefore were not deemed to be inappropriate. The development of a standardised methodology would provide a framework for comparing biochars with other biochars and amendments such as composts; and would allow more appropriate application of biochars to different soils.
- Subject
- biochar; soil; minesite rehabilitation; organic amendements
- Identifier
- http://hdl.handle.net/1959.13/1312194
- Identifier
- uon:22355
- Rights
- Copyright 2016 Andrew Thomas Regan
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | ATTACHMENT02 | Thesis | 6 MB | Adobe Acrobat PDF | View Details Download |