Journal ArticleDOI
Changes to water repellence of soil aggregates caused by substrate-induced microbial activity
Paul D. Hallett,Iain M. Young +1 more
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TLDR
In this article, the influence of microbial activity caused by adding plant nutrients on the hydraulic characteristics of soil aggregates is reported, and the results showed that the addition of nutrients caused severe water repellency in the aggregates.Abstract:
Summary
Soil microbes produce exudates which upon drying become water-repellent, thus altering hydraulic properties. The influence of microbial activity caused by adding plant nutrients on the hydraulic characteristics of soil aggregates is reported. Soil aggregates were collected from a field that had been fertilized with different amounts of nitrogen. Aggregates were also incubated with different nutrient treatments in the laboratory. Their sorptivity, hydraulic conductivity and water repellency were measured with a new device. Adding nitrogen was found to decrease sorptivity and hydraulic conductivity because of increased water repellency in the field. In the laboratory studies, the addition of nutrients caused severe water repellency in the soil aggregates. Respiration studies identified a large increase in biological activity following nutrient amendment which produces water-repellent materials.read more
Citations
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Journal ArticleDOI
A review of non-equilibrium water flow and solute transport in soil macropores: principles, controlling factors and consequences for water quality
TL;DR: The potential for non-equilibrium water flow and solute transport at any site depends on the nature of the macropore network, which is determined by the factors of structure formation and degradation as mentioned in this paper.
Journal ArticleDOI
Tolerable Versus Actual Soil Erosion Rates in Europe
TL;DR: In this paper, a modified definition of tolerable soil erosion is proposed as any actual soil erosion rate at which a deterioration or loss of one or more soil functions does not occur, with soil formation consisting of mineral weathering as well as dust deposition.
Journal ArticleDOI
Physical constraints affecting bacterial habitats and activity in unsaturated porous media – a review
Dani Or,Dani Or,Barth F. Smets,Jon M. Wraith,Arnaud Dechesne,Arnaud Dechesne,Shmulik P. Friedman +6 more
TL;DR: In this article, a review of the role of hydrologic conditions on microbial activity and their role in controlling macroscopic fluxes within the vadose zone is presented.
Journal ArticleDOI
Root‐ and microbial‐derived mucilages affect soil structure and water transport
TL;DR: In this paper, the authors used an experimental model with bacterial exopolysaccharides (dextran and xanthan) and root mucilage analogues (polygalacturonic acid, PGA), and up to 10 cycles of wetting and drying.
Journal ArticleDOI
Aggregate stability and microbial community dynamics under drying-wetting cycles in a silt loam soil
TL;DR: In this paper, the effects of drying-rewetting cycles on aggregate stability and on its main microbially mediated agents from a mechanistic point of view were evaluated and the results showed that the addition of straw stimulated microbial activity and increased the resistance to the three tests of aggregate stability, enhancing the internal cohesion and hydrophobicity of aggregates.
References
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Book
Physical and mineralogical properties, including statistics of measurement and sampling
TL;DR: Soil Acidity and LimingLaboratory Guide for Conducting Soil Tests and Plant AnalysisMethods of Soil Analysis Part 4 Physical MethodsSoil Analysis: Recent Trends and ApplicationsSoil Chemical MethodsBottom Soils, Sediment, and Pond AquacultureMethods in Applied Soil Microbiology and BiochemistrySoIL Analysis Handbook of Reference MethodsHandbook of reference Methods for Plant Analysis, Second EditionSoil Sampling, Preparation, and Analysis as discussed by the authors.
Journal ArticleDOI
Macroscopic and microscopic capillary length and time scales from field infiltration
I. White,M. J. Sully +1 more
TL;DR: In this paper, the authors derived relationships between λc and tc and readily measured field properties sorptivity S and hydraulic conductivity K or S at two supply heads, and showed that the microscopic characteristic length associated with λm gives physically plausible estimates of flow-weighted mean pore dimensions.
Book ChapterDOI
Soil Water Repellency
M. G. Wallis,David Horne +1 more
TL;DR: Water repellent soils exhibit hydrophobic properties when dry, resisting or retarding water infiltration into the soil matrix (Brandt, 1969a). Infiltration rates may be reduced by an order of magnitude, even in soils which visually appear to be wet.
Journal ArticleDOI
Clay- or sand-polysaccharide associations as models for the interface between micro-organisms and soil: water related properties and microstructure
TL;DR: In this article, experimental clay-polysaccharide associations were taken as models for the soil/biota interface, and their microstructure and physical properties were investigated, where special attention was given to control the water potential and to preserve, as far as possible, the organizations of the original hydrated conditions.
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