The use of high-resolution imaging tools for estimation of hydraulic soil properties and quantification of particulate organic matter

Pope, Daniela Diaz

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https://hdl.handle.net/2142/124415 Copy

Description

Title

The use of high-resolution imaging tools for estimation of hydraulic soil properties and quantification of particulate organic matter

Author(s)

Pope, Daniela Diaz

Issue Date

2024-04-30

Director of Research (if dissertation) or Advisor (if thesis)

• Wander, Michelle
• Ugarte, Carmen

Committee Member(s)

Grift, Tony

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• particulate organic matter
• soil imaging
• computed tomography
• fluorescence imaging
• porosity
• water retention

Abstract

Soil water holding capacity and particulate organic matter (POM) are important soil health indicators that are typically quantified in the lab using laborious methods. This work, divided into two projects, addresses methods for quantification of these important metrics using high resolution imaging techniques. In the first project, micro-computed tomography (µ-CT) was used to quantify plant available water using object-oriented image analysis of intact soil cores to reveal microscale features of 3D void space. Soil cores from the Morrow Plots, established in 1876 on a Flanagan silty clay loam, were used to assess the capability of µ-CT image-derived soil-water descriptors through comparison with estimates derived from soil moisture release curves. The use of µ-CT imaging to directly image soil structure allowed for direct quantification of pore connectivity, a variable that is not provided by soil moisture release curves. Estimates of plant available water were positively correlated with mesopore connectivity density and average mesopore diameter. The agreement between mean porosity values estimated using destructive and non-destructive methods confirms the efficacy of image-based analysis. The agreement between estimated water content using indirect versus direct measures of porosity for use in the double exponential water model also indicate the ability of directly quantified pore fractions to predict water content. A second project attempted to determine if volumetric quantification of POM using µ-CT estimates and fluorescence imaging methods was viable and could be optimized. Using deep learning methods, we identified significant fluorescent wavelength pairs using PARAFAC analysis that were associated with naturally occurring POM and soil organic matter. Despite this, and previous work suggesting CT was a viable method at the aggregate level, neither method produced area-based estimates of POM contents that were correlated with values determined in the lab. Notable variability in estimates obtained from different soil types and from soils that were sieved or left intact suggests that neither imaging technique can produce reliable estimates of POM. Chapter one identified strategies to formalize reproducible and effective imaging protocols for soil structural analysis. Application of these strategies in chapter two allowed us to determine that while fluorescence imaging is useful for OM quality assessment, neither it nor µ-CT methods are promising for volumetric POM quantification.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Daniela Pope

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