An Open Soil Structure Library based on X-ray CT data

Weller, Ulrich; Albrecht, Lukas; Schlüter, Steffen; Vogel, Hans‐Jörg

doi:10.5194/soil-2021-96

Cited by 3 publications

(5 citation statements)

References 18 publications

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“…The segmented pore classes at both resolutions, 19 and 50 μm, were analysed according to the typical pore characteristics, which are described in detail in Vogel et al (2010) and Weller et al (2021). The visible macroporosity, the distance between voxels classified as pores, the pore size distribution and two different pore connectivity characteristics were determined with Fiji ImageJ.…”

Section: Methodsmentioning

confidence: 99%

Response of subsoil organic matter contents and physical properties to long‐term, high‐rate farmyard manure application

Leuther

Wolff

Kaiser

et al. 2022

European J Soil Science

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Application of farmyard manure (FYM) is common practice to improve physical and chemical properties of arable soil and crop yields. However, studies on effects of FYM application mainly focussed on topsoils, whereas subsoils have rarely been addressed so far. We, therefore, investigated the effects of 36-year FYM application with different rates of annual organic carbon (OC) addition (0, 469, 938 and 1875 g C m À2 a À1 ) on OC contents of a Chernozem in 0-30 cm (topsoil) and 35-45 cm (subsoil) depth. We also investigated its effects on soil structure and hydraulic properties in subsoil. X-ray computed tomography was used to analyse the response of the subsoil macropore system (≥19 μm) and the distribution of particulate organic matter (POM) to different FYM applications, which were related to contents in total OC (TOC) and water-extractable OC (WEOC). We show that FYM-C application of 469 g C m À2 a À1 caused increases in TOC and WEOC contents only in the topsoil, whereas rates of ≥938 g C m À2 a À1 were necessary for TOC enrichment also in the subsoil. At this depth, the subdivision of TOC into different OC sources shows that most of the increase was due to fresh POM, likely by the stimulation of root growth and bioturbation. The increase in subsoil TOC went along with increases in macroporosity and macropore connectivity. We neither observed increases in plant-available water capacity nor in unsaturated hydraulic conductivity. In conclusion, only very high application of FYM over long periods can increase OC content of subsoil at our study site, but this increase is largely based on fresh, easily degradable POM and likely accompanied by high C losses when considering the discrepancy between OC addition rate by FYM and TOC response in soil. Highlights• A new image processing procedure to distinguish fresh and decomposed POM.• The increase of subsoil C stock based to a large extend on fresh, labile POM.

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Section: Methodsmentioning

confidence: 99%

Response of subsoil organic matter contents and physical properties to long‐term, high‐rate farmyard manure application

Leuther

Wolff

Kaiser

et al. 2022

European J Soil Science

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“…An open‐access “Soil Structure Library” aiming to provide such data was recently introduced by Weller et al. (2022). The main difference from the more holistic Meta soil model approaches (e.g., Grunwald et al., 2016) is that our 3–4D model approach aims at an explicit spatially resolved inventory of the solid phase dynamics of soils.…”

Section: Mechanistic Modelingmentioning

confidence: 99%

“…There are no validated and accepted pedotransfer functions that relate easily available attributes to structural properties such as pore size distribution or pore connectivity, which both are highly relevant for flow and transport. Recently, an open-access soil structure library was made available by Weller et al (2022), where 3D soil structure measurements are systematically linked to soil and site characteristics (i.e., soil texture, vegetation, land use, climatic region). This may form a valuable database to establish PTFs for soil structure.…”

Section: Soil Structure Modeling and Coupling With Mass Balancementioning

confidence: 99%

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3–4D soil model as challenge for future soil research: Quantitative soil modeling based on the solid phase

Gerke

Vogel

Weber

et al. 2022

J. Plant Nutr. Soil Sci.

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A 3-4D soil model represents a logical step forward from one-dimensional soil columns (1D), two-dimensional soil maps (2D), and three-dimensional soil volumes (3D) toward dynamic soil models (4D), with time as the fourth dimension. The challenge is to develop modeling tools that account for the states of soil properties, including the spatial structure of solids and pores, as well as their dynamics, including soil mass and solute transfers in landscapes. Our envisioned 3-4D soil model approach aims at improving the capability to predict fundamental soil functions (e.g., plant growth, storage, matter fluxes) that provide ecosystem services in the socioeconomic context.This study provides a structured overview on current soil models, challenges, open questions, and urgent research needs for developing a 3-4D soil model. A 3-4D soil model should provide an inventory of spatially distributed and temporally variable soil properties. As basis for this, we propose a mass balance model for the solid phase, which needs to be supplemented by a model describing its structure. This should eventually provide adequate 3D parameter sets for the numerical modeling of soil functions (e.g., flow and transport). The target resolution is decameters in the horizontal plane and centimeters to decimeters in the vertical direction to represent characteristic soil properties and soil horizons. The actual state of soils and their properties can be estimated from spatial data that represent the soil forming factors, with the use of machine learning tools. Improved modeling of the dynamics of soil bulk density, biological processes, and the pore structure are required to relate the solid mass balance to matter fluxes.A 3-4D soil model can be built from several types of modeling approaches. We distinguish between (1) process models that simulate mass balances, fluxes and soil structure dynamics, (2) statistical pedometric models using machine learning and geostatistics to estimate the soil inventory within landscapes, and (3) pedotransfer functions to link observable attributes to specific model parameters required to simulate soil functions including water and matter fluxes. This should provide the prerequisites to predict the spatial distribution of soil functions and their changes in response to external forcing. This endeavor can draw upon many already established models and techniques, yet combining them into a newly created 3-4D soil model is a truly an ambitious, but promisingThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Soil structure is among those parameters whose quantifications have been challenging in the soil physics literature. Hillel (2003) stated that, “The arrangement or organization of the particles in the soil (i.e., the internal configuration of the soil matrix) is called soil structure .” The structure of a soil might be characterized via different proposed parameters or indices and techniques, such as bulk density, aggregate size distribution and stability, gas adsorption, water retention curve, and imaging (Logsdon et al., 2013; Weller et al., 2021). For example, some researchers proposed the mass fractal dimension of aggregate size distribution to characterize soil structure (Chun et al., 2008; Giménez et al., 1998; Hirmas et al., 2013) and quantify its heterogeneity (Young & Crawford, 1991; Young et al., 2001).…”

Section: Introductionmentioning

confidence: 99%

Soil water retention curve inflection point: Insight into soil structure from percolation theory

Ghanbarian

Skaggs

2022

Soil Science Soc of Amer J

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Quantifying soil structure has been a long‐standing challenge in soil physics. Among the proposed indices and parameters, slope at the inflection point of soil water retention curve has been widely used. In this short communication, we provide theoretical insights and show that under full saturation conditions, the pore‐throat radius at the inflection point (rinf) is equivalent to the critical pore‐throat radius within percolation theory. The inflection point, in fact, corresponds to a critical saturation (critical fraction of pore space) at which a sample‐spanning cluster forms and a medium starts percolating. We discuss that rinf is theoretically linked to saturated hydraulic conductivity (Ksat), in a power‐law form within the critical path analysis framework. Using 59 soil samples from the GRIZZLY database, we show that the Ksat is correlated to the rinf, although there exists scatter in the data. Interestingly, the experimental exponent 2.219 found from the Ksat–rinf data is less than 5% greater than the estimated theoretical value 2.111 determined from the average fractal dimension of the measured soil water retention curves.

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An Open Soil Structure Library based on X-ray CT data

Cited by 3 publications

References 18 publications

Response of subsoil organic matter contents and physical properties to long‐term, high‐rate farmyard manure application

Response of subsoil organic matter contents and physical properties to long‐term, high‐rate farmyard manure application

3–4D soil model as challenge for future soil research: Quantitative soil modeling based on the solid phase

Soil water retention curve inflection point: Insight into soil structure from percolation theory

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