Wastewater treatment plants are shifting towards producing exceptional quality (EQ) biosolids to increase recycling rates to land, especially urban areas. Other methods of improving the environmental impact of wastewater treatment includes additions of iron (Fe) to reduce phosphorus (P) concentrations in outgoing treated water and precipitate the P into the biosolids. Proper management of biosolids to rehabilitate anthropogenically disturbed urban soils for improved plant growth and effects on the cycling of nutrients requires further study. Our objectives were: 1) to determine whether various EQ biosolids could be managed to improve degraded soil properties and turfgrass quality while minimizing risk of P loss in a field study; and 2) to use spectral reflectance data to compare relationships of vegetation indices to soil and turfgrass parameters. We found that after an initial lag-time of one year, biosolids amendments increased turfgrass clipping biomass and aesthetic quality greater than did synthetic fertilizer. Repeated topdressing applications of biosolids reduced soil bulk density and increased soil organic carbon (OC) and nitrogen (N) stocks. Biosolids applied at the agronomic N rate did not increase water-soluble P (15 and 18 mg P kg-1 of soil) compared to biosolids applied at the agronomic P rate (9.6 mg P kg-1 of soil) and synthetic fertilizer (13 mg P kg-1 of soil) after five years. We further demonstrated at this field site that collecting continuous data improves spectral reflectance vegetation indices relationships to turfgrass quality, clipping biomass, and tissue N accumulation. Soil volumetric water content was best correlated to the water band index (r = 0.60) and the green-to-red ratio index (r = 0.54) vegetation indices. Differences in soil and turfgrass measured parameters were best detected when there was drought-stressed versus irrigated turfgrass. / Doctor of Philosophy / Biosolids are the sanitized and nutrient-rich organic solids and semi-solids resulting from treatment of wastewater. The nutrient-rich organic solids provide plant-essential elements (e.g., nitrogen) and can improve soil physical parameters such as soil compaction. Wastewater treatment plants are adopting processes that produce cleaner, exceptional quality (EQ) biosolids to increase biosolids recycling rates to land, especially to urban areas to improve urban soil quality. Adding iron to treated wastewater further improves the quality of biosolids and effluent released to surface water by removing phosphorus from wastewater and concentrating this essential plant nutrient within biosolids. Our research objectives were to quantify the potential benefits of EQ biosolids for improving degraded urban soils, providing sufficient plant available nitrogen to improve turfgrass quality, avoiding increasing soil phosphorus to levels that could result in pollution, and increasing the long-term storage of soil carbon to mitigate climate change. We learned that biosolids were the best long-term solution for providing a high quality turfgrass stand and improve soil properties. Repeated applications of EQ biosolids reduced soil bulk density and increased soil organic carbon and nitrogen stocks. The increased iron in the biosolids reduced water-soluble phosphorus and may reduce phosphorus loss to surface waters.

The Irwin River catchment, located in the central western region of Western Australia, has been the scene of significant geomorphological change over both historical and geological timescales. This thesis focuses on the most recent of these changes, the anthropogenic imprint, through the development of a catchment-scale understanding of system behaviour. Analysis and modelling of changes in the hydrological behaviour of the system indicates that while the Irwin River has displayed a natural susceptibility to large flood events, these have been exacerbated by the widespread clearing of native vegetation throughout the catchment. As a result, when such events do occur, the catchment response is now larger, more direct and has a greater ability to cause erosion. However, the nature and detail of sediment yield processes and stream channel response varies markedly throughout the system. A series of representative channel reaches, as defined by their planform characteristics, geometry and architecture, are presented to illustrate spatial changes in stream channel behaviour. A distinct variation in river morphotypes is seen both downstream throughout the system as well as across the tributary sub-catchments of the Irwin River, Lockier River and Green Brook. This inter and intra sub-catchment variation in stream channel response can be attributed to changes in the boundary conditions and coupling mechanisms in operation throughout the Irwin River system. The pronounced spatial variability in response to human disturbance and the changing nature of catchment-scale connectivity seen in the Irwin River system differs markedly to that reported elsewhere in the literature. Appreciation of the variability in form, behaviour and evolutionary history throughout the Irwin River catchment not only provides the foundation for effective management but also contributes to a wider understanding of fluvial system behaviour. Unlike the majority of existing literature, which tends to identify and measure channel changes in a single catchment where historical variation to the sediment and discharge regime is well known, this study demonstrates the role of boundary conditions in determining the response of the fluvial system to changing environmental controls.