Complexed organic matter controls soil physical properties

Dexter, A. R.; Richard, Guy; Arrouays, Dominique; Czyż, Ewa A.; Jolivet, Claudy; Duval, Odile

doi:10.1016/j.geoderma.2008.01.022

Cited by 344 publications

(334 citation statements)

References 28 publications

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“…Figure 1 shows that the maximum value of correlation coefficient occurred at n = 14 and we assume that this is the appropriate value to use in Eqs (1-5). This is in contrast with Dexter et al (2008) who used the value of n at a pronounced inflection point in the curve of r against n for the soils that they used. However, in the present work we have not found any inflection point, but a maximum.…”

Section: Resultsmentioning

confidence: 82%

“…The complexing stabilizes the clay and thereby gives it a degree of protection against dispersion in water Emerson et al, 1986;Hassink and Whitmore, 1997). Dexter et al (2008) showed that, whereas non-complexed clay disperses readily in water, the complexed clay does not. This is an explanation for the observed increase in soil stability in water with increased content of OM.…”

Section: Introductionmentioning

confidence: 99%

“…A practical, working value of n = 10 for the soils that they used was determined from clay dispersion measurements by Dexter et al (2008). This concept has been evaluated independently by Schjønning et al (2011) for samples of 64 Danish soils and found to be valid.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Clay-organic complexes in a Polish loess soil

Czyż¹,

Rejman²,

Dexter³

et al. 2017

International Agrophysics

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Complexes formed between clay and soil organic matter are important for carbon sequestration and for soil physical quality. Here, we use samples of loessial soil from South-East Poland to explore the phenomenon of complexing in loess. Soil samples were collected from a single catchment 8 years after the introduction of strip tillage and their compositions were characterized by traditional methods. Complexing was characterized in terms of the content of non-complexed clay which was estimated in two ways: firstly, by measurement of the content of readily-dispersible clay (which was assumed to be the non-complexed clay); and secondly, by calculation using algorithms that had been developed and evaluated previously. The calculations were based on the concept that, at carbon saturation, the clay/organic carbon mass ratio is equal ton. The calculations were done with a range of values ofn. It was assumed that the correct value ofnwas that which gave the greatest coefficient of correlation between the measured values of clay dispersion and the predicted values of non-complexed clay. For the loess used, the optimum value wasn= 14.

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Section: Resultsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

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Clay-organic complexes in a Polish loess soil

Czyż¹,

Rejman²,

Dexter³

et al. 2017

International Agrophysics

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“…Alternatively, the organic matter can become saturated with clay, and any additional clay does not have enough organic matter to complex it. The first of these situations is common in forest or pasture soils, whereas the second is typical in the soils in arable agriculture (Dexter et al, 2008). The saturation of soil clay with organic matter has been tested experimentally and shown to occur (Schjønning et al, 2012;Stewart et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

“…The amounts of complexed and non-complexed organic carbon (COC and NCOC), and of complexed and noncomplexed clay (CC and NCC) may be calculated using the algorithmic method as described by Dexter et al (2008) and as evaluated by Schjønning et al (2012) using the following equations:…”

Section: Introductionmentioning

confidence: 99%

Estimation of the density of the clay-organic complex in soil

Czyż¹,

Dexter²

2016

International Agrophysics

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Soil bulk density was investigated as a function of soil contents of clay and organic matter in arable agricultural soils at a range of locations. The contents of clay and organic matter were used in an algorithmic procedure to calculate the amounts of clay-organic complex in the soils. Values of soil bulk density as a function of soil organic matter content were used to estimate the amount of pore space occupied by unit amount of complex. These estimations show that the effective density of the clay-organic matter complex is very low with a mean value of 0.17 ± 0.04 g ml−1 in arable soils. This value is much smaller than the soil bulk density and smaller than any of the other components of the soil considered separately (with the exception of the gas content). This low value suggests that the clay-soil complex has an extremely porous and open structure. When the complex is considered as a separate phase in soil, it can account for the observed reduction of bulk density with increasing content of organic matter.

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Pedotransfer Functions in Earth System Science: Challenges and Perspectives

Looy

Bouma

Herbst

et al. 2017

Reviews of Geophysics

397

297

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Soil, through its various functions, plays a vital role in the Earth's ecosystems and provides multiple ecosystem services to humanity. Pedotransfer functions (PTFs) are simple to complex knowledge rules that relate available soil information to soil properties and variables that are needed to parameterize soil processes. In this paper, we review the existing PTFs and document the new generation of PTFs developed in the different disciplines of Earth system science. To meet the methodological challenges for a successful application in Earth system modeling, we emphasize that PTF development has to go hand in hand with suitable extrapolation and upscaling techniques such that the PTFs correctly represent the spatial heterogeneity of soils. PTFs should encompass the variability of the estimated soil property or process, in such a way that the estimation of parameters allows for validation and can also confidently provide for extrapolation and upscaling purposes capturing the spatial variation in soils. Most actively pursued recent developments are related to parameterizations of solute transport, heat exchange, soil respiration, and organic carbon content, root density, and vegetation water uptake. Further challenges are to be addressed in parameterization of soil erosivity and land use change impacts at multiple scales. We argue that a comprehensive set of PTFs can be applied throughout a wide range of disciplines of Earth system science, with emphasis on land surface models. Novel sensing techniques provide a true breakthrough for this, yet further improvements are necessary for methods to deal with uncertainty and to validate applications at global scale.

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Complexed organic matter controls soil physical properties

Cited by 344 publications

References 28 publications

Clay-organic complexes in a Polish loess soil

Clay-organic complexes in a Polish loess soil

Estimation of the density of the clay-organic complex in soil

Pedotransfer Functions in Earth System Science: Challenges and Perspectives

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