Doctoral Thesis
Modeling and assessing hydraulic properties of selected Brazilian and Australian soils
Doctor of Philosophy (PhD), Murdoch University
2024
Abstract
Water availability is the main constraint for rainfed plant growth and current agricultural systems face the challenge of achieving high yields by optimizing the water use. The water dynamics in soils is governed by soil hydraulic properties and assessing these properties is essential for efficient water use in agriculture. In this sense, several soil management practices have been employed to improve soil water availability in agricultural fields, especially in water-limited regions. Thus, this study aimed to predict and assess soil hydraulic properties in two different scenarios: Brazilian (First part) and Australian soils (Second part). In the First part, a literature review was performed (Chapter I) to bring to light what was done in ten years (2012-2021) regarding the prediction of soil hydraulic properties. In Chapter II, machine learning techniques were used to create regional pedotransfer functions for an important tropical agricultural production region, the Mato Grosso state in Brazil. In the Second part, empirical models were tested for fitting soil water retention curves in Western Australian sandy soils including those modified by management practices (Chapter III). In Chapter IV, soil management strategies were assessed based on their effectiveness for enhancing water availability in Western Australian sandy soils. Results indicate that, overall, machine learning models are more accurate in predicting soil hydraulic properties compared to conventional regression approaches. Regional-specific models for predicting soil hydraulic properties of Mato Grosso state were established and are well trained for 91% of the state’s territory using basic predictors (particle size, bulk density, and water-dispersible clay). The Brooks and Corey model demonstrated superior performance and negligible bias in estimating soil water retention in Western Australian sandy soils. However, implementing the BC model in automated systems poses significant challenges. The addition of subsoil clay significantly increased total porosity and microporosity of sandy soils, but there was insufficient evidence to confirm an improvement in plant-available water. Overall, this thesis bring novelty into predicting, modeling, and assessing soil hydraulic properties in agricultural soils of Brazil and Australia.
Details
- Title
- Modeling and assessing hydraulic properties of selected Brazilian and Australian soils
- Authors/Creators
- Lucas de Castro Moreira da Silva
- Contributors
- Richard Bell (Supervisor) - Murdoch University, Centre for Sustainable Farming SystemsWendy Vance (Supervisor) - Murdoch University, Centre for Sustainable Farming SystemsLuca De Prato (Supervisor) - Murdoch University, Centre for Sustainable Farming SystemsRichard Amorin (Supervisor)Elpídio Fernandes Filho (Supervisor)
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005732482007891
- Murdoch Affiliation
- Centre for Sustainable Farming Systems; School of Agricultural Sciences
- Resource Type
- Doctoral Thesis
UN Sustainable Development Goals (SDGs)
This output has contributed to the advancement of the following goals:
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