Effect of root density of wheat and okra on hydraulic properties of an unsaturated compacted loam

Chen, Rui; Huang, Jun; Chen, Zhong Kui; Xu, Ying; Liu, Jian; Ge, Yang

doi:10.1111/ejss.12766

Cited by 39 publications

(21 citation statements)

References 41 publications

(55 reference statements)

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“…10.1680/jgeot.19.p.058 Chen et al, 2019;Tao et al, 2019). Unsaturated permeability also can be determined using empirical formulations, macroscopic models, or statistical models involving SWRCs (Leong and Rahardjo, 1997;Patil and Singh, 2016).…”

Section: Introductionmentioning

confidence: 99%

Measurements of permeability of saturated and unsaturated soils

Pandey

Lynch²,

Sivakumar

et al. 2021

Géotechnique

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The management and engineering assessments of geotechnical assets within the national transportation inventory require an appropriate knowledge of permeability of saturated and unsaturated soils. Determination of the permeability of saturated soils can be carried out using direct measurements, whereas that of unsaturated soils is often made using indirect methods based on Soil Water Retention Curve (SWRC). In this study an attempt was made to develop a novel approach for measuring the saturated and unsaturated permeability of soils. The tests were conducted on 100mm diameter reconstituted and compacted samples of glacial till. Suctions were generated by circulating low humidity air through a slender sand column located at the centre of the samples. Measurements of suction were made by two tensiometers located radially at the base of the samples. The drying process was terminated when the observed suctions reached or approached the limiting capacity of the tensiometers (1500 kPa). Combinations of suction measurements and volumetric strains during the drying process were used to determine the permeability by adopting analytical solutions as applicable to a radial flow condition.

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Section: Introductionmentioning

confidence: 99%

Measurements of permeability of saturated and unsaturated soils

Pandey

Lynch²,

Sivakumar

et al. 2021

Géotechnique

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“…These techniques fall into three main categories: physical techniques (e.g., vibration [20,21]), mechanical techniques [22], and chemical techniques (e.g., admixture stabilization [23]).Reinforcing soil using randomly distributed fibers dates from more than 5000 years ago when plant roots and stems were used to reinforce building blocks. This technique still remains a hot research issue nowadays and its application fields are widening [24][25][26][27]. The advantages of mixing fibers into soil include increases in shear, compressive, and tensile strength [28][29][30][31]; a reduction in the swelling tendency of expansive soil [32][33][34]; reduced brittleness [35][36][37][38]; and so forth.…”

mentioning

confidence: 99%

Behavior of Fiber-Reinforced and Lime-Stabilized Clayey Soil in Triaxial Tests

Wang

Guo

et al. 2019

Applied Sciences

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The beneficial role of combining fiber reinforcement with lime stabilization in altering soil behavior has been established in the literature. However, the coupling effect of their combination still remains unclear in terms of its magnitude and microscopic mechanism, especially for natural fibers with special microstructures. The objective of this study was to investigate the coupling effect of wheat straw fiber reinforcement and lime stabilization on the mechanical behavior of Hefei clayey soil. To achieve this, an experimental program including unconsolidated–undrained (UU) triaxial tests and SEM analysis was implemented. Static compaction test samples were prepared on untreated soil, fiber-reinforced soil, lime-stabilized soil, and lime-stabilized/fiber-reinforced soil at optimum moisture content with determining of the maximum dry density of the untreated soil. The lime was added in three different contents of 2%, 4%, and 6%, and 13 mm long wheat straw fiber slices with a cross section one-quarter that of the intact ones were mixed in at 0.2%, 0.4%, and 0.6% by dry weight of soil. Analysis of the derived results indicated that the addition of a small amount of wheat straw fibers into lime-stabilized soil improved the intensity of the strain-softening behavior associated with mere lime stabilization. The observed evidence that the shear strength increase brought by a combination of 0.4% fiber reinforcement and 4% lime stabilization was smaller than the summation of the shear strength increases brought by their presence alone in a sample demonstrated a coupling effect between fiber reinforcement and lime stabilization. This coupling effect was also detected in the comparisons of the secant modulus and failure pattern between the combined treatment and the individual treatments. These manifestations of the coupling effect were explained by a microscopic mechanism wherein the fiber reinforcing effect was made more effective by the ways in which lime chemically stabilized the soil and lime stabilization development was quickened by the water channels passing through the surfaces and honeycomb pores of the wheat straw fibers.

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“…Plant roots also exert important indirect controls on soil structure formation through plant water uptake and soil shrinkage (Jotisankasa & Sirirattanachat, 2017; Kay, 1990) and by increasing the stability of the soil to resist mechanical stresses (e.g. Bearden, 2001; Chen et al., 2019; Hallett et al., 2009; Kohler‐Milleret, Le Bayon, Chenu, Gobat, & Boivin, 2013; Milleret, Le Bayon, Lamy, Gobat, & Boivin, 2009). They are also a major source of the organic carbon supplied to soil (Haichar, Heulin, Guyonnet, & Achouak, 2016; Jones, Nguyen, & Finlay, 2009), which drives the activity and growth of soil microorganisms and fauna, and thus the development of an aggregated soil structure.…”

Section: Biological Agents Of Soil Structure Dynamicsmentioning

confidence: 99%

A framework for modelling soil structure dynamics induced by biological activity

Meurer

Barron

Chenu

et al. 2020

Global Change Biology

100

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Soil degradation is a worsening global phenomenon driven by socio‐economic pressures, poor land management practices and climate change. A deterioration of soil structure at timescales ranging from seconds to centuries is implicated in most forms of soil degradation including the depletion of nutrients and organic matter, erosion and compaction. New soil–crop models that could account for soil structure dynamics at decadal to centennial timescales would provide insights into the relative importance of the various underlying physical (e.g. tillage, traffic compaction, swell/shrink and freeze/thaw) and biological (e.g. plant root growth, soil microbial and faunal activity) mechanisms, their impacts on soil hydrological processes and plant growth, as well as the relevant timescales of soil degradation and recovery. However, the development of such a model remains a challenge due to the enormous complexity of the interactions in the soil–plant system. In this paper, we focus on the impacts of biological processes on soil structure dynamics, especially the growth of plant roots and the activity of soil fauna and microorganisms. We first define what we mean by soil structure and then review current understanding of how these biological agents impact soil structure. We then develop a new framework for modelling soil structure dynamics, which is designed to be compatible with soil–crop models that operate at the soil profile scale and for long temporal scales (i.e. decades, centuries). We illustrate the modelling concept with a case study on the role of root growth and earthworm bioturbation in restoring the structure of a severely compacted soil.

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Effect of root density of wheat and okra on hydraulic properties of an unsaturated compacted loam

Cited by 39 publications

References 41 publications

Measurements of permeability of saturated and unsaturated soils

Measurements of permeability of saturated and unsaturated soils

Behavior of Fiber-Reinforced and Lime-Stabilized Clayey Soil in Triaxial Tests

A framework for modelling soil structure dynamics induced by biological activity

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