Harris, Christina (2022) A Protocol for Assessing Soil Condition and Capability: A Southern Downs Case Study. Honours thesis, University of Southern Queensland. (Unpublished)
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Abstract
There is no established methodology to measure a change in soil condition in a way that captures the undisturbed state and compares it to the composition of soil in its current managed state. Previous attempts have relied on assessments at two or more points on the timeline of management history that do not recognise the land’s initial state, mainly a pre-colonial era soil with low-intensity human interventions. Insights into the soils’ natural capacity to perform given functions and deliver ecosystem services are largely missed. Recreating pre-colonial conditions is a critical challenge in the typically degraded Australian agricultural soil; thus, a proxy for the farmed land is beneficial. To test the hypothesis that management of a mixed-horticultural farming system over 70 years had a negative effect on soil condition, a protocol was developed to examine land use impacts at a farming enterprise on the Queensland Southern Downs. The landscape was surveyed, and the soil was sampled in the remnant native vegetation and the cleared area historically used for horticultural farming. Laboratory analysis of soil texture, and chemical properties of pH, electrical conductivity (EC), cation and effective cation exchange capacity (eCEC), and exchangeable sodium percentage (ESP) were conducted and formed the basis of soil attributes used to define the land use areas. The protocol identified a suitable proxy site to form the benchmark or baseline status for the farmed land by assessing comparable soil-forming factors; key environmental covariates, and soil texture. Propensity score matching techniques enabled the pairing of three proxy native vegetative soils to the suite of farmed soils. This approach progresses the Soil Security Framework (SSF) agenda, particularly the condition and capability dimensions. The landscape entity, the terron, was coupled with SSF to facilitate digital soil mapping of the regional soil attributes and environmental features. At the farm scale, ordinary kriging interpolation illustrated changes in the soil attributes. The results did not support the hypothesis, as no negative effect was observed, and divergences in the chemical properties were generally positive. However, in this demonstrative case study, the protocol was found to be an effective means of quantifying a change in soil condition, signalling where and to what degree degradation is likely to have occurred in farmed areas. The scope of this study was restricted to a single farming enterprise on the Southern Downs and was later modified to remove the intended regional level terron analysis; nevertheless, it provided a protocol that appears promising. More testing is required to for protocol replication across different landscapes and industries. In future, landowners can identify proxies and target corrective actions for soils on-farm and provide a means to improve degraded soils as part of interconnecting landscapes. Ultimately, the developed protocol and other tools which aim to quantify soil capability, support a shift toward sustainable management practices for long-term soil security.
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| Item Type: | Thesis (Non-Research) (Honours) |
|---|---|
| Item Status: | Live Archive |
| Additional Information: | File reproduced in accordance with the copyright policy of the publisher/author. |
| Faculty/School / Institute/Centre: | Historic - Faculty of Health, Engineering and Sciences - School of Sciences (6 Sep 2019 - 31 Dec 2021) |
| Supervisors: | Bennett, John |
| Qualification: | Bachelor of Science Honours: Environment & Sustainability |
| Date Deposited: | 15 Apr 2026 02:12 |
| Last Modified: | 15 Apr 2026 02:12 |
| Uncontrolled Keywords: | Soil security framework; Native vegetation; Ecosystem services; Degradation; Soil capacity and condition; Digital soil mapping |
| Fields of Research (2020): | 41 ENVIRONMENTAL SCIENCES > 4106 Soil sciences > 410601 Land capability and soil productivity 41 ENVIRONMENTAL SCIENCES > 4106 Soil sciences > 410602 Pedology and pedometrics |
| Socio-Economic Objectives (2020): | 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180605 Soils |
| URI: | https://sear.unisq.edu.au/id/eprint/51763 |
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