Intrinsic and model polymer hydrogel-induced soil structural stability of a silty sand soil as affected by soil moisture dynamics

Buchmann, Christian; Bentz, Jonas; Schaumann, Gabriele E.

doi:10.1016/j.still.2015.06.014

Cited by 33 publications

(30 citation statements)

References 69 publications

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“…Organic compounds increase soil aggregation and resistance (Zhang and Hartge, 1990;Markgraf et al, 2012;Buchmann et al, 2015) by augmenting cohesion and number of menisci in unsaturated conditions (Zhang and Hartge, 1990;Bachmann and Zhang, 1991). Furthermore, with increasing w t , organic compounds and salts are precipitated in contact areas between particles and aggregates, increasing soil resistance to deformation (Soulié et al, 2007;Holthusen et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

Rheological Parameters as Affected by Water Tension in Subtropical Soils

Pértile

Reichert

Gubiani

et al. 2016

Rev. Bras. Ciênc. Solo

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Rheological parameters have been used to study the interaction between particles and the structural strength of soils subjected to mechanical stresses, in which soil composition and water content most strongly affect soil resistance to deformation. Our objective was to evaluate the effect of water tension on rheological parameters of soils with different mineralogical, physical, and chemical composition. Surface and subsurface horizons of four Oxisols, two Ultisols, one Alfisol, and one Vertisol were physically and chemically characterized; their rheological parameters were obtained from amplitude sweep tests under oscillatory shear on disturbed soil samples that were saturated and subjected to water tension of 1, 3, 6, and 10 kPa. In these samples, the rheological parameters linear viscoelastic deformation limit (γ L ), maximum shear stress (τ max ), and integral z were determined. By simple regression analysis of the rheological parameters as a function of soil water tension, we observed increased mechanical strength with increasing water tension up to at least 6 kPa, primarily due to increased capillary forces in the soil. However, increased elasticity assessed by γ L was not as expressive as the increase in structural rigidity assessed by τ max and integral z. Elastic deformation of the soil (γ L ) increases with the increase in the number of bonds among particles, which depend on the clay, total carbon, expansive clay mineral, and cation contents; however, maximum shear resistance (τ max ) and structural stiffness (integral z) mainly increase with clay, kaolinite, and oxide content by increasing the strength of interparticle bonds. A decrease in mechanical strength occurs for water tension of 10 kPa (the lowest water content evaluated) in sandy horizons or in horizons with a high proportion of resistant microaggregates (pseudosand), when associated with low bulk density, due to fewer points of contact between soil particles and therefore lower capillary force.

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Section: Resultsmentioning

confidence: 99%

Rheological Parameters as Affected by Water Tension in Subtropical Soils

Pértile

Reichert

Gubiani

et al. 2016

Rev. Bras. Ciênc. Solo

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“…In the amplitude sweep tests, there is also great influence of normal stress (σ) on rheological properties (Buchmann et al, 2015). We observed responsive increases in initial moduli G' and G" caused by an increase of the σ, as annotated by an increase in the initial normal stress (σ i ); (because the MCR 102 rheometer is not able to record the σ during testing, the σ i is manually annotated).…”

Section: Difficulties and Opportunitiesmentioning

confidence: 93%

Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities

Pértile

Holthusen

Gubiani

et al. 2018

Sci. agric. (Piracicaba, Braz.)

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ABSTRACT:The structural strength of soils has been extensively described by physical and mechanical properties evaluated on the mesoscale for different soils and management conditions. However, changes in the organization of the soil matrix at the microstructural level, which can be obtained by rheometry, are still seldom used in soil mechanics. Our aim was to use the amplitude sweep test, a rheometry technique, to investigate the microstructural strength of four subtropical soils (two Oxisols, an Ultisol and a Vertisol) and to discuss difficulties with respect to the samples, water content, soil density and vertical force. The various rheological properties which reveal the soil microstructural strength were determined: deformation at the end of the linear viscoelastic range, LVE range (γ LVE ), shear stress at the end of the LVE range (τ LVE ), deformation at yield point, YP (γ YP ), storage and loss moduli at YP (G'G" YP ), maximum shear stress (τ max ), and integral z. In general, soil elasticity (γ LVE and γ YP ) and microstructural strength (τ LVE and τ max ) were greater in the Oxisols and the Vertisol, which both possess high clay content, while the latter also contains expansive clay minerals. The lowest structural strength was observed in the Ultisol which had a high sand content. As rheological properties are related to soil properties such as particle size distribution and carbon content, they can be applied in the evaluation of the microstructural strength of clayey and sandy soils and allows for inferences regarding interparticle shear strength. However, the test is not applicable to very dry soil samples and sample preparations can affect the results. We suggest a number of approaches to find solutions for these difficulties/problems.

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“…Studies directly characterizing biopolymers typically use welldefined polysaccharide model substances such as polygalacturonic acid (PGA) or agarose (Gessa and Deiana, 1992;Strathmann et al, 2001Strathmann et al, , 2000. For biohydrogels-rich soils, model polymers are also used to investigate complex processes induced by biohydrogels (Buchmann et al, 2015). In soil, the use of model polymers arises from the difficulties to study the impact of one single biohydrogel property in macroscopic observations.…”

Section: Can Biopolymer Characteristics Be Mimicked By Well-defined Mmentioning

confidence: 99%

“…Root, microbial and fungal biohydrogels have been demonstrated to stabilize the soil structure (Watt et al, 1994;Zhang et al, 2008;Barré and Hallett, 2009;Peng et al, 2011;Albalasmeh and Ghezzehei, 2014;Buchmann et al, 2014). This process is complex and depends on the nature of exudates (Barré and Hallett, 2009;Peng et al, 2011), clay content (Barré and Hallett, 2009;Buchmann et al, 2015), soil structure rigidity (Peng et al, 2011), amount of organic matter (Albalasmeh and Ghezzehei, 2014;Buchmann et al, 2015Buchmann et al, , 2014, and moisture dynamics (Peng et al, 2011). Swelling-shrinking of biohydrogels induced by moisture dynamics is supposed to increase bond strength between particles (Czarnes et al, 2000) and to influence a reorientation of soil particles and their gluing by organic structures (Peng et al, 2011;Buchmann et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

“…The ability of hydrogels to modify soil physicochemical properties, such as water holding capacity, soil structural stability and thus soil productivity, has already been employed with the use of soil amendments such as synthetic hydrogels for agricultural purposes (Hedrick and Mowry, 1952;Johnson, 1984;Guilherme et al, 2015). Current approaches assessing interactions between synthetic hydrogels and the mineral soil body are based either on soil hydrological properties, e.g., its hydraulic conductivity or water storage (Al-Darby, 1996;Santos and Serralheiro, 2000;Andry et al, 2009;Levy and Warrington, 2015), or on mechanical properties defined by the soil microstructure and its stability against external forces (Bai et al, 2010;Mamedov et al, 2007;Peng et al, 2011;Buchmann et al, 2015). Although these studies provide some information on the interaction between hydrogels and soil and their impact on soil properties, they rather focus on the effects on soil properties than on the processes governing these properties.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Biohydrogel induced soil–water interactions: how to untangle the gel effect? A review

Brax

Buchmann

Schaumann

2017

J. Plant Nutr. Soil Sci.

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Biohydrogels such as microbial exudates and root‐derived mucilage are soil‐born cross‐linked polymers, able to form porous three‐dimensional networks during water uptake. The gel effect is the variation of soil properties, such as soil hydrology and soil structural stability, resulting from biohydrogel swelling in soil. Conventionally, soil–water–hydrogel interactions are investigated by measuring soil bulk properties such as water retention curves and porosity, without further analyzing the effect of biohydrogel phases in soil on a quantitative basis. Therefore, the evaluation of advanced and novel methods for the characterization of biohydrogel phases in soil and soil–water–hydrogel interactions is necessary. This review evaluates currently available methods for their potential to analyze processes associated to the gel effect. A promising approach to investigate the spatio‐temporal distribution of biohydrogel phases in porous media is based on Nuclear Magnetic Resonance (NMR) such as 1H‐NMR relaxometry, as well as on imaging techniques such as Environmental Scanning Electron Microscopy (ESEM). Especially NMR techniques enable the identification of different water populations based on their differences in the relaxation, and thus the mobility of water molecules in biohydrogels and non‐gel water in soil pores. Rheology measures the flow behavior of biohydrogels, providing information on the structural behavior of the hydrogel network and its gelling mechanism. Soil rheology further quantifies the effect of the biohydrogel phases on the interactions between soil particles, and thus the impact on soil microstructural stability. However, rheology does not elucidate the spatio‐temporal distribution and structural state of biohydrogel phases in soil. All in all, a systematic combination of rheology, NMR and suitable imaging methods seems promising and necessary in order to elucidate the still widely unknown gel effect in soil.

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Intrinsic and model polymer hydrogel-induced soil structural stability of a silty sand soil as affected by soil moisture dynamics

Cited by 33 publications

References 69 publications

Rheological Parameters as Affected by Water Tension in Subtropical Soils

Rheological Parameters as Affected by Water Tension in Subtropical Soils

Microstructural strength of four subtropical soils evaluated by rheometry: properties, difficulties and opportunities

Biohydrogel induced soil–water interactions: how to untangle the gel effect? A review

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