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This paper describes the application of fractal geometry to the study of the structure and dynamics of tilled silty topsoil. The soil structure of each topsoil sample has been experimentally quantified directly by image analysis and indirectly by both water retention and mercury porosimetry. Any fractal scaling laws were mostly determined within a relevant common pore radius yardstick scale. Their...
The effects of structural changes on Cerrado Oxisols in Brazil after land-use change are still insufficiently studied. Therefore, topsoil samples of loamy and clayey Cerrado Oxisols under crop, pasture and reforestation were fractionated using a wet-sieving procedure to obtain the distribution of water-stable aggregates and compared to samples from natural savanna. The results were correlated to organic...
Reports about the relationship between soil water retention and organic carbon content are contradictory. We hypothesized that this relationship is affected by both proportions of textural components and amount of organic carbon. To test the hypothesis, we used the U.S. National Soil Characterization database and the database from pilot studies on soil quality as affected by long-term management....
Ferralsols under native vegetation have a weak to moderate macrostructure and a well-developed microstructure corresponding to subrounded microaggregates that are usually 80 to 300 μm in size. The aim of this study was to analyze how the hydraulic properties of a clay Ferralsol were affected by a change of structure when the native vegetation is cleared for pasture. We studied the macrostructure in...
Detailed particle-size distribution (PSD) data or parameters derived from it are used in almost all pedotransfer functions (PTFs) to estimate soil hydraulic properties. Most commonly, the PSD is represented by the sand, silt and clay content of a soil. However, a number of standards exist and are in use internationally to describe PSD and particle-size classes. Additionally, some authors use derived...
The Brazilian Central Plateau covers about 40% of the Cerrados Biome and represents 24% of the Brazilian territory. The Latosols correspond to about 40% of the Central Plateau. We analyzed the hydraulic properties of a set of Latosols varying according to clay content and mineralogy along a regional toposequence across the Brazilian Central Plateau. We studied the properties of the diagnostic horizon...
The colour of a soil changes with its water content. This paper investigates the ability of spectrophotometric colour measurement to predict soil mass wetness (w). We looked at the CIELAB parameters (L ⁎ , C ⁎ab , h ab ) and spectral profile of 76 A soil-horizons from south-eastern Spain to (i) group them by colour, (ii) calibrate within each group the relationships between...
Re-packed soil columns of the Crediton series were sown with white clover or perennial ryegrass, with nitrate managed according to organic and conventional farming regimes respectively. Visual observations revealed a rapid enhancement in soil structure beneath white clover compared to ryegrass and unplanted soil. Enhanced structural differentiation beneath white clover was supported by greater permeability...
A double-exponential water retention equation with 5 adjustable parameters is introduced in order to fill the need for a user-friendly equation in which all the terms have a distinct physical meaning. It is compared with the van Genuchten [van Genuchten, M.Th., 1980. A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci. Soc. Am. J. 44, 892–898] equation in...
This paper reviews an existing method of class pedotransfer function development, ‘the Wösten method’, reproducing previous results by this method, and introduces a statistically more stringent refinement, ‘the Transformation method’. Direct comparison of the Wösten method and a Box–Cox Transformation method shows that these two methods produce equivalent predictions of the average values of water...
Soil hydraulic properties, mainly saturated and unsaturated hydraulic conductivity and water retention, are crucial input parameters in any modelling study on water flow and solute transport in soils. However, direct measurement techniques remain relatively time consuming, labour intensive and expensive. Fortunately, they may be predicted by forming a mathematical relationship between relatively easily...
It is shown that, for mineral soils, it is not the total amount of organic carbon (or organic matter) that controls soil physical behaviour but the amount of complexed organic carbon (COC). We assume that this complex is formed by the association of unit mass (i.e. 1 g) of organic carbon with n grams of clay. Analysis of data from two French and two Polish databases shows that, for these soils, n=10...
In recent years, considerable changes in the management of agricultural land have been observed in the Carpathian region. The aim of this study was to quantify the effects of different land-management systems in mountainous regions on the air–water properties of soil. The field trial was established in the period 2005–2007 on the Haplic Cambisol Dystric soil in the south of Poland, Central Europe...
Water retention characteristic (WRC) is an important soil property used in many hydrologic applications. Although there are numerous models in the literature for its prediction, the models are largely empirical with fundamental derivations based on soil textural pore-spaces. This paper presents a biexponential model for WRC that has its basis on textural and structural soil pore-spaces. The model...
The imposition of agricultural systems changes the natural equilibrium of the soil to an extent that it becomes dependant on management practices and soil resilience. Agroforestry systems (AFs) mimic characteristics of natural ecosystems such as multistrata canopy and deep rooting and may minimize the consequences of these changes by providing soil protection and maintenance of conditions similar...
Crop rotations with a high proportion of cereals, including monoculture, are typical in many countries in Europe. Although wheat is the most popular cereal as it is cultivated world-wide, in recent years a steady increase has been observed in triticale production. The objective of the study was to determine the effect of different crop rotations using triticale on soil air–water properties with a...
The red clay soils which are widespread in China are known to be highly sensitive to drought during the dry season but the origin of this high sensitivity to drought remains unclear. Several red clay soils were selected in the Hunan province for study. We studied their basic physico-chemical properties and clay mineralogy, their structure and shrinkage properties, as well as their water retention...
A field experiment was conducted during the period of 2011 to 2012 to study the effect of traffic on physical properties of soil when different turfgrass species were cultivated. Experimental plots were established with three replications in a split-plot design with species as a main plot and traffic treatment as a subplot. The traffic treatment was applied to the turfgrass using Brinkman traffic...
Over the last decade, the application of biochar (BC) as a soil amendment to sequester carbon and mitigate global climate change has received considerable attention. While positive effects of biochar on plant nutrition are well documented, little is known about potential impacts on the physical properties of soils, especially on water retention at low matric potentials. To overcome this knowledge...
Adding carbon-rich solids from pyrolysis (pyrochars) and hydrothermal carbonization (hydrochars) to soils can improve their hydraulic properties and increase the plant available soil water capacity (AWC). However, the effects of the specific char characteristics on soil hydraulic properties are still little understood and thus, difficult to optimize for soil amendment. It is often assumed that the...
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