Abstract
Soils deliver the regulating ecosystem services of water infiltration and distribution, which can be controlled by macropores. Parameterizing macropore hydraulic properties is challenging due to the lack of direct measurement methods. With tension-disc infiltrometry hydraulic properties near saturation can be measured. Differentiating between hydrologically active and non-active pores, at a given water potential, indirectly assesses macropore continuity. Water flow through macropores is controlled by macropore size distribution, tortuosity, and connectivity, which can be directly derived by X-ray computed tomography (CT). Our objective was to parameterize macropore hydraulic properties based on the imaged macropore network of three horizons of an Andosol and a Gleysol. Hydraulic conductivity Kunsat was derived from infiltration measurements. Soil cores from the infiltration areas were scanned with X-ray CT. Kunsat was significantly higher in the Andosol than in the Gleysol at all water potentials, and decreased significantly with depth in both soils. The in situ measurements guided the definition of new macroporosity parameters from the X-ray CT reconstructions. For the Andosol, Kunsat was best predicted using the imaged-limited macroporosity. A low total macroporosity, coupled with a high macropore density, indicated the abundance of smaller macropores, leading to homogeneous matrix flux. Imaged macropores were not well connected. In contrast, the Gleysol had a bi-modal macropore system with few very large, but well-connected macropores. Kunsat was best predicted using the imaged macroporosity consisting only of macropores with diameters between 0.75 and 3 mm. Our research demonstrates that linking traditional soil physical measurements with soil-visualization techniques has a huge potential to improve parameterizing macropore hydraulic properties. The relevance of the relationships found in this study for larger scales and other soil types still needs to be tested, for example by a multi-scale investigation including a much wider range of different soils.
Original language | English (US) |
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Pages (from-to) | 82-91 |
Number of pages | 10 |
Journal | Geoderma |
Volume | 313 |
DOIs | |
State | Published - Mar 1 2018 |
Bibliographical note
Funding Information:This research was funded through Landcare Research under the Ministry for Business, Innovation and Employment (Contract 1314-32-001K ). Parts of the work were supported by the European Union's Horizon 2020 Research and Innovation Project under grant agreement no. 645717 (PROTINUS project). We thank Drs Markus Deurer and John Scott for initiating this research.
Publisher Copyright:
© 2017 Elsevier B.V.
Keywords
- Hydraulic parameters
- Image analysis
- Pore network
- Soil structure
- Tension disc infiltrometry
ASJC Scopus subject areas
- Soil Science