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J. Deckers - One of the best experts on this subject based on the ideXlab platform.
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Landform Analysis, Vol. 17: 215–218 (2011) Impact of land use and Soil properties on piping in Belgium
2016Co-Authors: Els Verachtert, J. Poesen, Steven Devoldere, Miet Van, Den Eeckhaut, J. DeckersAbstract:Abstract: Field observations and literature reveal that land use and Soil characteristics play an important role in the devel-opment of piping. In this study, the hypothesis is tested that discontinuities in the Soil profile favour piping erosion in loess-derived Soils in a temperate humid climate. Abiotic characteristics (clay content, bulk density, Ksat, penetration resis-tance) and the biological activity in the Soil were measured for each Soil Horizon until a depth of at least 40 cm below the pipes (ca. 1.30 m) for 12 representative Soil profiles with different land use (pasture with and without collapsed pipes, arable land and forest). No clear discontinuities in abiotic characteristics were observed at Soil depths where subsurface pipes oc-curred, but pastures with piping had significantly more earthworm channels and mole burrows at larger depths than pastures without piping, arable land or forest
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estimating the effect of tree uprooting on variation of Soil Horizon depth by confronting pedogenetic simulations to measurements in a belgian loess area
Journal of Geophysical Research, 2013Co-Authors: Peter Finke, T. Vanwalleghem, J. Poesen, Emmanuel Opolot, J. DeckersAbstract:[1] Spatial patterns of Soil often do not reflect those of topographic controls. We attempted to identify possible causes of this by comparing observed and simulated Soil Horizon depths. Observed depths of E, Bt, BC, C1, and C2 Horizons in loess-derived Soils in Belgium showed a weak to absent relation to terrain attributes in a sloping area. We applied the Soil genesis model SoilGen2.16 onto 108 1 × 1 m2 locations in a 1329 ha area to find possible causes. Two scenarios were simulated. Model 1 simulated Soil development under undisturbed conditions, taking slope, aspect, and loess thickness as the only sources of variations. Model 2 additionally included a stochastic submodel to generate tree-uprooting events based on the exposure of trees to the wind. Outputs of both models were converted to depths of transitions between Horizons, using an algorithm calibrated to Horizon depths observed in the field. Model 1 showed strong correlations between terrain attributes and depths for all Horizons, although surprisingly, regression kriging was not able to model all variations. Model 2 showed a weak to absent correlation for the upper Horizons but still a strong correlation for the deeper Horizons BC, C1, and C2. For the upper Horizons the spatial variation strongly resembled that of the measurements. This is a strong indication that bioturbation in the course of Soil formation due to treefalls influences spatial patterns of Horizon depths.
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Spatial variability of Soil Horizon depth in natural loess-derived Soils
Geoderma, 2010Co-Authors: T. Vanwalleghem, Alex B. Mcbratney, J. Poesen, J. DeckersAbstract:Abstract Soil variability across landscapes is well known and results from the combination of geomorphologic and pedogenetic processes. Despite its importance, little quantitative information exists on the Horizontal and vertical variation of Soil profiles, especially in natural landscapes that are unaffected by Soil erosion. This study aims at measuring the variation in Soil Horizon depth in loess-derived Soils and relating it to surface characteristics. Several terrain variables and the variable Soil type, as derived from existing Soil maps, are considered in the prediction model. In total 399 augerings of up to 8.7 m deep were made in natural forest areas in Central Belgium, where Soil profiles were not affected by anthropogenic Soil erosion. The variability of 5 different Soils Horizons was evaluated: eluvial (E) and illuvial clay (Bt) Horizons, transition Horizon (BC), decalcified loess material (C1) and undisturbed calcareous loess material (C2). All Horizons exhibited significant variability. The top two Soil Horizons could not be linked significantly to any of the predictor variable. For the lower three Soil Horizons some weak, yet significant relations were found with the predictor variables slope gradient, plan curvature, wetness index, landform and Soil type. Geostatistical analysis indicated a lack of spatial dependence for all Horizons, except for the upper eluvial E Horizon. This high spatial randomness resulted in poor predictions models for the depth of these Soil Horizons, with model efficiencies ranging between − 0.14 and 0.08, while for the E Horizon, a simple ordinary kriging model provided a model efficiency of 0.43.
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Spatial variability of Soil Horizon depth in natural loess-derived Soils
Geoderma, 2010Co-Authors: T. Vanwalleghem, J. Poesen, A. Mcbratney, J. DeckersAbstract:Soil variability across landscapes is well known and results from the combination of geomorphologic and pedogenetic processes. Despite its importance, little quantitative information exists on the Horizontal and vertical variation of Soil profiles, especially in natural landscapes that are unaffected by Soil erosion. This study aims at measuring the variation in Soil Horizon depth in loess-derived Soils and relating it to surface characteristics. Several terrain variables and the variable Soil type, as derived from existing Soil maps, are considered in the prediction model. In total 399 augerings of up to 8.7 m deep were made in natural forest areas in Central Belgium, where Soil profiles were not affected by anthropogenic Soil erosion. The variability of 5 different Soils Horizons was evaluated: eluvial (E) and illuvial clay (Bt) Horizons, transition Horizon (BC), decalcified loess material (C1) and undisturbed calcareous loess material (C2). All Horizons exhibited significant variability. The top two Soil Horizons could not be linked significantly to any of the predictor variable. For the lower three Soil Horizons some weak, yet significant relations were found with the predictor variables slope gradient, plan curvature, wetness index, landform and Soil type. Geostatistical analysis indicated a lack of spatial dependence for all Horizons, except for the upper eluvial E Horizon. This high spatial randomness resulted in poor predictions models for the depth of these Soil Horizons, with model efficiencies ranging between −0.14 and 0.08, while for the E Horizon, a simple ordinary kriging model provided a model efficiency of 0.43.status: publishe
R. G. Kachanoski - One of the best experts on this subject based on the ideXlab platform.
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Scale-dependent covariance of Soil physical properties above and below a Soil Horizon interface: Pedogenic versus anthropogenic influences on total porosity
Canadian Journal of Soil Science, 2011Co-Authors: Miles Dyck, R. G. KachanoskiAbstract:Dyck, M. F. and Kachanoski, R. G. 2011. Scale-dependent covariance of Soil physical properties above and below a Soil Horizon interface: Pedogenic versus anthropogenic influences on total porosity. Can. J. Soil Sci. 91: 149–159. The basic unit of Soil – the pedon – is described as the minimum, three-dimensional unit of Soil representative of the variability of Soil Horizon dimensions and morphology. Pedogenic processes responsible for Soil Horizon and Soil profile formation are primarily hydrologic in nature. The spatially variable distribution of Soil Horizons (i.e., the variation among pedons within catenae or landscapes) is likely a reflection of the inherent variability of the Soil parent material and the spatial variability of hydrological/pedogenic processes. This paper explores the spatial variability and spatially scale-dependent covariance between a basic Soil property (porosity) above and below an A/B Horizon interface under adjacent disturbed (cultivated) and undisturbed (forested) conditions. ...
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Measurement of Steady-State Soil Water Flux across a Soil Horizon Interface
Soil Science Society of America Journal, 2009Co-Authors: M. F. Dyck, R. G. KachanoskiAbstract:Soil Horizon interfaces have been shown to be focal points for localized, three-dimensional redistribution of water and solutes in field Soils. Therefore, understanding of the physics of water flow and transport in layered Soils requires experimental observations of the magnitude and variability of local Soil water flux under a variety of well-defined boundary conditions. We developed a time domain reflectometry (TDR) method to measure the spatial pattern of steady-state, local Soil water flux density above and below a Soil Horizon interface under quasi-steady surface water application and implemented it in laboratory and field experiments. Time series of TDR-measured bulk Soil electrical conductivity and TDR-measured Soil volumetric water content at each location are used to quantify the solute travel time under steady-state flow conditions, which is then used to quantify steady-state, local Soil water flux density. Results from laboratory and field experiments showed that the proposed methodology yielded local Soil water flux density estimates that were, on average, 104% of the applied surface water flux density (i.e., mass recovery = 104%), which is consistent with transient, local Soil water flux density estimates from a previous study. For the field experiments, steady-state, local Soil water flux density estimates above and below an A/B Horizon interface (measured across the length of a 6.75-m transect) were negatively correlated to each other. The strength of the negative correlation, however, decreased with increasing surface water application rate, suggesting that the hydrologic response of the Soil Horizon interface is flux-dependent. This flux-dependent correlation between A and B Horizon steady-state Soil water flux density is probably attributable to the spatial covariance between A and B Horizon Soil hydraulic properties.
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Measurement of Transient Soil Water Flux Across a Soil Horizon Interface
Soil Science Society of America Journal, 2009Co-Authors: Miles Dyck, R. G. KachanoskiAbstract:Understanding the physics oF water flow and transport in layered Soils requires experimental observations of the magnitude and variability of these processes as they occur in the field. In this study, a time domain reflectometry (TDR) method to measure the spatial pattern of transient, local Soil water flux above and below a Soil Horizon interface under quasi-steady surface water application was developed and implemented in laboratory and field experiments. The method uses vertical TDR probes spanning two or more Soil Horizons or layers. Time series of Soil water storage measured by the TDR probes are used to quantify transient, local Soil water flux during infiltration under quasi-steady surface water application. Results from the laboratory and field experiments showed that transient Soil water flux estimates with the presented methodology were, on average, 106% of the applied water flux (i.e., mass recovery = 106%). Furthermore, in field experiments, excellent agreement between two independent measurements of local Soil water flux through the A Horizon showed that this methodology is robust and sensitive to spatial variations in Soil water flux within Soil Horizons and changes in local Soil water flux as the wetting front crosses the interface between two Horizons. In the field experiments, transient local Soil water flux through the A and B Horizons (measured along a 6.75-m-long transect) were positively correlated to each other, but the strength of the correlation decreased with increasing surface water application rates. The flux-dependent covariance between the measured patterns of transient A and B Horizon Soil water flux indicates that the Soil Horizon interface is a hydrologically significant component of the Soil profile. In-depth spatial analysis of the measured Soil water flux patterns is the subject of a future study.
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Field Solute Transport across a Soil Horizon Boundary
Soil Science Society of America Journal, 1992Co-Authors: C. J. Hamlen, R. G. KachanoskiAbstract:Models describing solute transport in a field Soil need to account for transport through Soil Horizons and across Horizon boundaries. This study investigated the effects of Soil Horizons on the transport of a conserving tracer and the validity of treating Soil Horizons as independent (uncorrelated) layers. The occurrence or absence of correlated solute travel times with depth was tested by comparing predicted solute travel time variances with variances measured from solute breakthrough curves. Steady-state transport experiments were conducted on a Fox sand (fine-loamy over sandy or sandy-skeletal, mixed, mesic Typic Hapludalf) in Ontario, Canada. The transport of Cl through the Ap and the Ap + B Horizons was measured at constant surface flux densities of 3.5 and 5.5 cm h⁻¹. The upper 20 cm of Soil was then excavated and the transport of Cl through the B Horizon was measured independently at a flux density of 5.5 cm h⁻¹. The Horizons exhibited differences in solute velocity, spatial variations in velocity and in equilibrium water contents. At the transect scale, successful predictions of travel time variance were made at both flux densities when it was assumed that solute travel times were correlated with depth. At the local scale, the successful prediction of variance assuming correlated travel times occurred only at the lower flux density. At this site a correlated model is appropriate for describing solute transport at the transect scale. Independent estimates of transport properties from each Horizon is not sufficient information to predict field transport. The nature of the boundary between Horizons must be evaluated. Contribution from the Dep. of Land Resource Science, Univ. of Guelph, and the Univ. of Waterloo Centre for Groundwater Research, Waterloo, ON, Canada N2L 3G1.
Susan E. Trumbore - One of the best experts on this subject based on the ideXlab platform.
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Radiocarbon Dating of Soil Organic Matter
Quaternary Research, 1996Co-Authors: Yang Wang, Ronald Amundson, Susan E. TrumboreAbstract:Radiocarbon ages of Soil organic matter are evaluated with a model which incorporates the dynamics of the14C content of Soil organic matter. Measured14C ages of Soil organic matter or its fractions are always younger than the true ages of Soils due to continuous input of organic matter into Soils. Differences in Soil C dynamics due to climate or Soil depth will result in significantly different14C signatures of Soil organic matter for Soils of the same age. As a result, the deviation of the measured14C age from the true age of Soil formation could differ significantly among different Soils or Soil Horizons. Our model calculations also suggest that14C ages of Soil organic matter will eventually reach a steady state provided that no climatic or ecological perturbations occur. Once a Soil or a Soil Horizon has reached a steady state,14C dating of Soil organic matter will provide no useful information regarding the age of the Soil. However, for Soils in which steady state has not been reached, it is possible to estimate the age of Soil formation by modeling the measured14C contents of Soil organic matter. Radiocarbon dating of buried Soils could, in general, overestimate the true age of the burial by as much as the steady-state age of the Soil or Soil Horizon.
Margaret S Torn - One of the best experts on this subject based on the ideXlab platform.
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long term decomposition the influence of litter type and Soil Horizon on retention of plant carbon and nitrogen in Soils
Biogeochemistry, 2017Co-Authors: Caitlin Hicks E Pries, Jeffrey A Bird, C Castanha, Pierrejoseph Hatton, Margaret S TornAbstract:How plant inputs from above- versus below-ground affect long term carbon (C) and nitrogen (N) retention and stabilization in Soils is not well known. We present results of a decade-long field study that traced the decomposition of 13C- and 15N-labeled Pinus ponderosa needle and fine root litter placed in O or A Soil Horizons of a sandy Alfisol under a coniferous forest. We measured the retention of litter-derived C and N in particulate (>2 mm) and bulk Soil (<2 mm) fractions, as well as in density-separated free light and three mineral-associated fractions. After 10 years, the influence of slower initial mineralization of root litter compared to needle litter was still evident: almost twice as much root litter (44% of C) was retained than needle litter (22–28% of C). After 10 years, the O Horizon retained more litter in coarse particulate matter implying the crucial comminution step was slower than in the A Horizon, while the A Horizon retained more litter in the finer bulk Soil, where it was recovered in organo-mineral associations. Retention in these A Horizon mineral-associated fractions was similar for roots and needles. Nearly 5% of the applied litter C (and almost 15% of the applied N) was in organo-mineral associations, which had centennial residence times and potential for long-term stabilization. Vertical movement of litter-derived C was minimal after a decade, but N was significantly more mobile. Overall, the legacy of initial litter quality influences total SOM retention; however, the potential for and mechanisms of long-term SOM stabilization are influenced not by litter type but by Soil Horizon.
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Long term decomposition: the influence of litter type and Soil Horizon on retention of plant carbon and nitrogen in Soils
Biogeochemistry, 2017Co-Authors: Caitlin E. Hicks Pries, Jeffrey A Bird, C Castanha, Pierrejoseph Hatton, Margaret S TornAbstract:How plant inputs from above- versus below-ground affect long term carbon (C) and nitrogen (N) retention and stabilization in Soils is not well known. We present results of a decade-long field study that traced the decomposition of 13C- and 15N-labeled Pinus ponderosa needle and fine root litter placed in O or A Soil Horizons of a sandy Alfisol under a coniferous forest. We measured the retention of litter-derived C and N in particulate (>2 mm) and bulk Soil (
T. Vanwalleghem - One of the best experts on this subject based on the ideXlab platform.
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estimating the effect of tree uprooting on variation of Soil Horizon depth by confronting pedogenetic simulations to measurements in a belgian loess area
Journal of Geophysical Research, 2013Co-Authors: Peter Finke, T. Vanwalleghem, J. Poesen, Emmanuel Opolot, J. DeckersAbstract:[1] Spatial patterns of Soil often do not reflect those of topographic controls. We attempted to identify possible causes of this by comparing observed and simulated Soil Horizon depths. Observed depths of E, Bt, BC, C1, and C2 Horizons in loess-derived Soils in Belgium showed a weak to absent relation to terrain attributes in a sloping area. We applied the Soil genesis model SoilGen2.16 onto 108 1 × 1 m2 locations in a 1329 ha area to find possible causes. Two scenarios were simulated. Model 1 simulated Soil development under undisturbed conditions, taking slope, aspect, and loess thickness as the only sources of variations. Model 2 additionally included a stochastic submodel to generate tree-uprooting events based on the exposure of trees to the wind. Outputs of both models were converted to depths of transitions between Horizons, using an algorithm calibrated to Horizon depths observed in the field. Model 1 showed strong correlations between terrain attributes and depths for all Horizons, although surprisingly, regression kriging was not able to model all variations. Model 2 showed a weak to absent correlation for the upper Horizons but still a strong correlation for the deeper Horizons BC, C1, and C2. For the upper Horizons the spatial variation strongly resembled that of the measurements. This is a strong indication that bioturbation in the course of Soil formation due to treefalls influences spatial patterns of Horizon depths.
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Spatial variability of Soil Horizon depth in natural loess-derived Soils
Geoderma, 2010Co-Authors: T. Vanwalleghem, Alex B. Mcbratney, J. Poesen, J. DeckersAbstract:Abstract Soil variability across landscapes is well known and results from the combination of geomorphologic and pedogenetic processes. Despite its importance, little quantitative information exists on the Horizontal and vertical variation of Soil profiles, especially in natural landscapes that are unaffected by Soil erosion. This study aims at measuring the variation in Soil Horizon depth in loess-derived Soils and relating it to surface characteristics. Several terrain variables and the variable Soil type, as derived from existing Soil maps, are considered in the prediction model. In total 399 augerings of up to 8.7 m deep were made in natural forest areas in Central Belgium, where Soil profiles were not affected by anthropogenic Soil erosion. The variability of 5 different Soils Horizons was evaluated: eluvial (E) and illuvial clay (Bt) Horizons, transition Horizon (BC), decalcified loess material (C1) and undisturbed calcareous loess material (C2). All Horizons exhibited significant variability. The top two Soil Horizons could not be linked significantly to any of the predictor variable. For the lower three Soil Horizons some weak, yet significant relations were found with the predictor variables slope gradient, plan curvature, wetness index, landform and Soil type. Geostatistical analysis indicated a lack of spatial dependence for all Horizons, except for the upper eluvial E Horizon. This high spatial randomness resulted in poor predictions models for the depth of these Soil Horizons, with model efficiencies ranging between − 0.14 and 0.08, while for the E Horizon, a simple ordinary kriging model provided a model efficiency of 0.43.
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Spatial variability of Soil Horizon depth in natural loess-derived Soils
Geoderma, 2010Co-Authors: T. Vanwalleghem, J. Poesen, A. Mcbratney, J. DeckersAbstract:Soil variability across landscapes is well known and results from the combination of geomorphologic and pedogenetic processes. Despite its importance, little quantitative information exists on the Horizontal and vertical variation of Soil profiles, especially in natural landscapes that are unaffected by Soil erosion. This study aims at measuring the variation in Soil Horizon depth in loess-derived Soils and relating it to surface characteristics. Several terrain variables and the variable Soil type, as derived from existing Soil maps, are considered in the prediction model. In total 399 augerings of up to 8.7 m deep were made in natural forest areas in Central Belgium, where Soil profiles were not affected by anthropogenic Soil erosion. The variability of 5 different Soils Horizons was evaluated: eluvial (E) and illuvial clay (Bt) Horizons, transition Horizon (BC), decalcified loess material (C1) and undisturbed calcareous loess material (C2). All Horizons exhibited significant variability. The top two Soil Horizons could not be linked significantly to any of the predictor variable. For the lower three Soil Horizons some weak, yet significant relations were found with the predictor variables slope gradient, plan curvature, wetness index, landform and Soil type. Geostatistical analysis indicated a lack of spatial dependence for all Horizons, except for the upper eluvial E Horizon. This high spatial randomness resulted in poor predictions models for the depth of these Soil Horizons, with model efficiencies ranging between −0.14 and 0.08, while for the E Horizon, a simple ordinary kriging model provided a model efficiency of 0.43.status: publishe
