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Bruno Delvaux - One of the best experts on this subject based on the ideXlab platform.
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porosity and soil water properties of caribbean volcanic ash soils
Soil Use and Management, 2006Co-Authors: Marc Dorel, Jean Rogerestrade, Hubert Manichon, Bruno DelvauxAbstract:Volcanic ash soils are generally recognized as soils with excellent and stable physical properties. Here we characterized the porosity and water properties of volcanic ash Andosols and Nitisols from Guadeloupe in contrasting banana systems: (1) perennial crop without mechanization, (2) mechanized and regularly replanted crop. Desiccation from 1 kPa to 1550 kPa moisture tension leads to significant shrinkage in the Andosol, representing a 50% reduction of the void space. The clayey Nitisol exhibited limited shrinkage. Soil clods from the mechanized plots had a significantly smaller macroporosity than that from perennial plots. The soil hydraulic conductivity was also drastically reduced in the compacted layers of the mechanized plots. However, Nitisols appeared to be less affected than Andosols. Laboratory compression tests showed that both soils were susceptible to compaction at soil moisture close to field capacity. The shrinkage properties of the Andosol were due to microaggregation of non-crystalline components upon drying. The relative stability of the macroporosity in the Nitisol was probably related to the presence of stable microaggregates made of halloysite and iron oxide. Two major processes promote soil structure degradation in the Andosol under mechanized banana cropping, surface desiccation and soil compaction. They are both induced by repeated tillage after clearing.
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contribution of so3 to the acid neutralizing capacity of Andosols exposed to strong volcanogenic acid and so2 deposition
European Journal of Soil Science, 2005Co-Authors: Thomas Delfosse, Pierre Delmelle, Anne Iserentant, Bruno DelvauxAbstract:Soil response to acid and sulphur inputs is influenced largely by the soil's physico-chemical properties. We studied the effects of such depositions in two types of Andosols exposed to volcanogenic emission (Masaya, Nicaragua), namely Eutric Andosols rich in allophanic constituents, and Vitric Andosols rich in volcanic glass. Small mineral reserves and large contents of secondary short-range ordered minerals indicate a more advanced weathering of the Eutric than the Vitric Andosols. Strong correlations between soil specific surface and oxalate-extractable Al, Si and Fe contents highlight the predominant contribution of short-range ordered minerals to surface area. Both types of Andosols showed a decrease in pH upon acid input. Sulphur deposition increased the soil's S content to 5470 mg S kg(-1). However, the acid neutralizing capacity of the soil solid phase (ANC(s)) was not significantly affected by the acid and S inputs. Non-exchangeable (mineral reserve) and exchangeable cations and total contents of sulphur and phosphorus dictate most of the ANC(s) variation. In the Vitric Andosols, mineral reserves contributed up to 97% to these four additive pools, whereas the exchangeable cations accounted for 1-4%. In the Eutric Andosols, the contribution of mineral reserves was less (71-92%), but the exchangeable cation content was greater (1-20%), whereas the contribution of sulphur and phosphorus was significant at 1-15% and 2-7%, respectively. The main process involved in H+ consumption is mineral weathering in Vitric Andosols and ion exchange in Eutric Andosols.
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selective sorption of potassium in a weathering sequence of volcanic ash soils from guadeloupe french west indies
Catena, 2004Co-Authors: Samuel Ndayiragije, Bruno DelvauxAbstract:Volcanic ash soils are usually associated within the weathering sequence glass --> allophane --> 4 halloysite. On the eastern slopes of the volcano La Soufriere, Guadeloupe, this sequence occurs in a toposequence Molli-silicic Andosol-Humic Andosol-Haplic Andosol-Haplic Nitisol, where the average annual rainfall decreases from 4000 mm at 420 m a.s.l. to 2500 mrn at 30 m a.s.l. Of this sequence, we selected four profiles and examined the relationships between weathering stage, clay mineralogy and exchangeable K+-Ca2+ selectivity. With increasing weathering, the total content of alkaline and alkaline-earth cations of the B horizon steadily decreased from 185 cmol(c) kg(-1) soil in the Molli-silicic Andosol to 24 cmol(c), kg(-1) soil in the Nitisol. K+ selectivity was small in the Molli-silicie Andosol, but significantly increased with increasing weathering stage and increasing content of halloysite. In the Haplic Andosol and Nitisol, the very strong selectivity for K+ ions may be linked with the presence of a 2:1 clay mineral, but could not be attributed unequivocally to this mineral or to halloysite. The 2:1 mineral occurred as a discrete phase mixed with halloysite and exhibited X-ray diffraction features, suggesting its vermiculitic nature. (C) 2003 Elsevier B.V. All rights reserved.
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sulfate chloride and fluoride retention in Andosols exposed to volcanic acid emissions
Environmental Pollution, 2003Co-Authors: Pierre Delmelle, Thomas Delfosse, Bruno DelvauxAbstract:The continuous emissions of SO(2), HCl and HF by Masaya volcano, Nicaragua, represent a substantial source of atmospheric S-, Cl- and F-containing acid inputs for local ecosystems. We report on the effects of such acid depositions on the sulfate, chloride and fluoride contents in soils (0-40 cm) from two distinct transects located downwind from the volcano. The first transect corresponds to relatively undifferentiated Vitric Andosols, and the second transect to more weathered Eutric Andosols. These soils are exposed to various rates of volcanogenic acid addition, with the Vitric sites being generally more affected. Prolonged acid inputs have led to a general pH decrease and reduced exchangeable base cation concentrations in the Andosols. The concentrations of 0.5 M NH(4)F- and 0.016 M KH(2)PO(4)-extractable sulfate (NH(4)F-S and KH(2)PO(4)-S, respectively) indicate that volcanic S addition has increased the inorganic sulfate content of the Vitric and Eutric soils at all depths. In this process, the rate of sulfate accumulation is also dependent on soil allophane contents. For all soils, NH(4)F extracted systematically more (up to 40 times) sulfate than KH(2)PO(4). This difference suggests sulfate incorporation into an aluminum hydroxy sulfate phase, whose contribution to total inorganic sulfate in the Vitric and Eutric Andosols is estimated from approximately 34 to 95% and approximately 65 to 98%, respectively. The distribution of KH(2)PO(4)-extractable chloride in the Vitric and Eutric Andosols exposed to volcanic Cl inputs reveals that added chloride readily migrates through the soil profiles. In contrast, reaction of fluoride with Al and Fe oxyhydroxides and allophanes is an important sink mechanism in the Masaya Andosols exposed to airborne volcanic F. Fluoride dominates the anion distribution in all soil horizons, although F is the least concentrated element in the volcanic emissions and depositions. The soil anion distribution reflects preferential retention of fluoride over sulfate and chloride, and of sulfate over chloride. The primary acidifying agent of the Andosols subject to the volcanic acid inputs is HCl.
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coexistence of allophane gibbsite kaolinite and hydroxy al interlayered 2 1 clay minerals in a perudic andosol
Geoderma, 2003Co-Authors: Samuel Ndayiragije, Bruno DelvauxAbstract:Allophane and halloysite are the most common secondary aluminosilicate minerals in Andosols developed in pyroclasts in humid tropical areas. We studied the composition and the charge properties of the clays extracted from the weathered B horizon of a perhydrated Andosol developed in andesitic ash in Guadeloupe, French West Indies, by selective dissolution, X-ray diffraction (XRD), thermal analysis and characterization of ion exchange properties. The Bw horizon contained weatherable minerals and exhibited an allophane content of 25%. Its clay fraction contained gibbsite, allophane, kaolinite and hydroxy-Al interlayered 2:1 clay minerals. The occurrence of gibbsite, allophane and kaolinite was linked with intense leaching of silica. After oxalate dissolution of allophane, the cation exchange capacity (CEC) was 11.8 cmol(c) kg(-1) clay, i.e. a typical value for low-activity clays. Subsequent citrate treatment completely dissolved gibbsite, but partly extracted Al interlayers from the hydroxy-Al-interlayered phase. This extraction led to a 5.6-fold increase of the cation exchange capacity (62.3 cmol(c) kg(-1) clay) and a 2.3-fold increase in K+ selectivity. The 2:1 clay minerals involved a combination or continuum of high-charge beidellite and vermiculite. From our data, we believe that the 2:1 clay minerals first acted as a sink for aluminium and might have expressed an anti-gibbsitic effect. After substantial Al interlayering of 2:1 clay minerals mimicking low-activity clay, gibbsite might have formed in a second stage. (C) 2003 Elsevier Science B.V. All rights reserved.
Randy A. Dahlgren - One of the best experts on this subject based on the ideXlab platform.
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mineralogical and surface charge characteristics of Andosols experiencing long term land use change in west java indonesia
Soil Science and Plant Nutrition, 2020Co-Authors: Markus Anda, Randy A. DahlgrenAbstract:Extensive areas of Andosols in tropical Indonesia have been subjected to long-term (>100 years) alterations from native forest to agricultural land use. This study assessed the mineralogical and su...
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nature properties and function of aluminum humus complexes in volcanic soils
Geoderma, 2016Co-Authors: Tadashi Takahashi, Randy A. DahlgrenAbstract:© 2015 Elsevier B.V. Andosols (or Andisols) possess several distinctive properties that are rarely found in other groups of soils. These properties are largely due to the dominance of short-range-ordered minerals (allophane, imogolite and ferrihydrite) and/or metal-humus complexes (Al/Fe-humus complexes) in their colloidal fraction. While several papers have extensively reviewed the nature and properties of short-range-ordered minerals, there is no comprehensive review of the genesis, characteristics and management implications of Al-humus complexes, the dominant form of active Al in non-allophanic Andosols. In this review, we survey the chemical characteristics of Al-humus complexes and discuss the pedogenic environment favoring their formation in non-allophanic Andosols. The role of Al-humus complexes in carbon cycling and soil organic carbon accumulation is emphasized as an important mechanism controlling organic dynamics in Andosols. While non-allophanic Andosols share many common properties with allophanic Andosols, they display several distinct characteristics associated with Al-humus complexes, such as strong acidity and high exchangeable Al content that impair agricultural productivity due to Al phytotoxicity. Thus, we focus on the role of Al-humus complexes in regulating aqueous Al3+ solubility and release/retention kinetics, Al phytotoxicity, phosphorus dynamics, and suppression of soil-borne diseases. Knowledge of these soil properties as related to Al-humus complexes is necessary to develop effective soil management practices to assure sustainable agricultural productivity in non-allophanic Andosols. Finally, future research needs are identified concerning the role of Al-humus complexes in regulating soil biogeochemical processes.
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Chapter 7 Physical Characteristics of Volcanic Ash Soils
Developments in soil science, 2008Co-Authors: M. Nanzyo, Sadao Shoji, Randy A. DahlgrenAbstract:Publisher Summary Volcanic ash soils have many unique physical properties that are attributable directly to the properties of the parent material, the noncrystalline materials formed by weathering, and the soil organic matter accumulated during soil formation. These properties include dark soil color, difficult clay dispersion, unique consistence, low bulk density, and high water holding capacity. Soil color is the most striking feature observed for volcanic ash soils, especially for their A horizons. Andisols typically display a large difference in texture when comparing field and laboratory determination methods. Noncrystalline materials play an important role as cementing agents and react with an excess amount of sodium hexametaphosphate. Furthermore, each of the inorganic colloids shows a different point of zero net charge, so that complete dispersion of mineral particles is virtually impossible. Andisols generally have low bulk densities that are attributable to the development of highly porous soil structure. Andisols usually show low degrees of stickiness, plasticity, and hardness that result from the abundance of noncrystalline materials and/or soil organic matter. These physical properties also provide an excellent environment for root growth. Andisols have well-developed soil structure resulting in high porosity with a range of pore sizes that retain a large amount of water with varying tensions.
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evaluation and proposed revisions of criteria for Andosols in the world reference base for soil resources
Soil Science, 1996Co-Authors: Sadao Shoji, Randy A. Dahlgren, Masami Nanzyo, Paul QuantinAbstract:The proposed criteria for Andosol classification in the World Reference Base (WRB) of Soil Resources were evaluated using the Tohoku University World Andosol Database (TUWAD). The WRB proposal defines a diagnostic andic horizon comprised of vitr-andic, alu-andic, and sil-andic subtypes, and eight
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aluminum release rates from allophanic and nonallophanic Andosols
Soil Science and Plant Nutrition, 1994Co-Authors: Randy A. Dahlgren, Masahiko SaigusaAbstract:Abstract Aluminum release rates were studied for subsoil horizons of allophanic and nonallophanic Andosols and for imogolite gel films. Release rates were determined using a stirred, flow-through reaction vessel with a 10−3 M acetate buffer adjusted to pH 3.3, 3.8, or 4.2. To determine the sources of dissolved AI, soils were pretreated with Kel, Na-pyrophosphate, citrate-bicarbonate-dithionite, and acid oxalate to remove various solid-phase pools of active AI. Rates of Al release for imogolite gel films during the first minute of reaction ranged from 74.8 nmol/gls at pH 4.2 to 113.3 nmol/g/s at pH 3.3. Rates of AI release for nonallophanic Andosols were greater than for allophanic Andosols due to the rapid release of exchangeable Al from nonallophanic Andosols. Aluminum release rates showed fractional order H+ -dependence ranging from 0.23 to 0.54. The primary source of dissolved Al in allophanic Andosols was from AI-humus complexes and allophane/imogolite. In nonallophanic Andosols, exchangeable Al and A...
Jorge D Etchevers - One of the best experts on this subject based on the ideXlab platform.
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transport sorption and degradation of atrazine in two clay soils from mexico andosol and vertisol
Geoderma, 2014Co-Authors: B Prado, Celine Duwig, Claudia Hidalgo, Karin Muller, L Mora, Elias Raymundo Raymundo, Jorge D EtcheversAbstract:Although atrazine has been banned in the European Union, it is still one of the most widely used herbicides in the world. It is has been detected in surface and groundwater and has been shown to be associated with major human health problems. Atrazine fate in the environment, e.g. sorption, leaching and degradation depends, inter alia, on soil characteristics. Independent static and dynamic experiments were conducted to identify and uncouple the processes governing the fate of atrazine. Two agricultural soils from Mexico with contrasting characteristics in terms of organic matter content and degree of decomposition as well as clay types were selected. Soil organic matter was the main sorbent for atrazine, followed by montmorillonite clays in the Vertisol, and iron oxides and allophanes in the Andosol. Humic acids were predominant in the Andosol's organic matter and favored atrazine sorption, compared to more recalcitrant organic matter such as humin fractions in the Vertisol. Atrazine mobility was enhanced because of the occurrence of preferential flow in the upper layer of the Vertisol and because of the formation of mobile complexes between dissolved organic carbon and atrazine in the Andosol. Our detailed soil characterization and the independent sorption, degradation and transfer experiments allowed identifying the main processes affecting atrazine's fate in the two contrasting soils: In the Vertisol, preferential flow was enhanced because of the lower affinity of the soil's organic matter for atrazine compared to the Andosol. The application of atrazine to Vertisol soils poses a higher risk for groundwater contamination than its application to Andosols.
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image processing based study of soil porosity and its effect on water movement through andosol intact columns
Agricultural Water Management, 2009Co-Authors: B Prado, Patrice Delmas, P Morales, Jason James, J. Marquez, Celine Duwig, Jorge D EtcheversAbstract:The soil pore network and marcoporosity are important factors affecting water and solute transport. The transfer of contaminants to water resources is of particular importance in the Valle de Bravo watershed as it provides 10% of the drinking water for the 20 million inhabitants of Mexico City. This watershed is composed mainly of Andosols with unique mineralogical and physical characteristics. Soil porosity is usually examined on thin sections, using various image analysis techniques. We propose a novel methodology combining image analysis and a displacement experiment to study relationships between soil structure and water tracer transport parameters. H218O displacement experiments were conducted through intact soil columns sampled at three depths from a representative cultivated Andosol profile. The soil structure and pore characteristics were obtained by image analysis on thin sections obtained from each column at the end of the displacement experiment. The total 2D porosity (for pores larger than 50[mu]m) varied from 80% of the total section area in the topsoil to around 60% in the subsoil. Tubular pores were the most abundant in the soil profile, but ploughing of the topsoil had destroyed sections of these pores and replaced them with packing pores. Water transport in the intact subsoil columns was always in physical non-equilibrium, showing the existence of preferential flow pathways. In the topsoil, one column out of three showed no preferential flow, demonstrating that soil ploughing also homogenised pore connections. Pore connectivity was larger in the ploughed topsoil than in their deeper soil horizon counterparts. Our methodology offers a 2D quantitative characterisation of the macroporous network at 50[mu]m resolution and the determination of water transport parameters on the same intact soil samples. 3D characterisation of soil porosity using X-ray computed tomography (CT) gives a better picture of pore connection but usually has lower spatial resolution and a larger cost.
Magalie Jannoyer - One of the best experts on this subject based on the ideXlab platform.
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Physical limitation of pesticides (chlordecone) decontamination in volcanic soils: fractal approach and numerical simulation
Environmental science and pollution research international, 2019Co-Authors: Thierry Woignier, Luc Rangon, Florence Clostre, Charles Mottes, Philippe Cattan, Juan Primera, Magalie JannoyerAbstract:In the French West Indies, the chlordecone (organochloride pesticide) pollution is now diffuse becoming new contamination source for crops and environment (water, trophic chain). Decontamination by bioremediation and chemical degradation are still under development but the physical limitations of these approaches are generally not taken into account. These physical limitations are related to the poor physical accessibility to the pesticides in soils because of the peculiar structural properties of the contaminated clays (pore volume, transport properties, permeability, and diffusion). Some volcanic soils (Andosols), which represent the half of the contaminated soils in Martinique, contain nanoclay (allophane) with a unique structure and porous properties. Andosols are characterized by pore size distribution in the mesoporous range, a high specific surface area, a large pore volume, and a fractal structure. Our hypothesis is that the clay microstructure characteristics are crucial physico-chemical factors strongly limiting the remediation of the pesticide. Our results show that allophane microstructure (small pore size, hierarchical microstructure, and tortuosity) favors accumulation of chlordecone, in Andosols. Moreover, the clay microporosity limits the accessibility of microorganisms and chemical species able to decontaminate because of poor transport properties (permeability and diffusion). We model the transport properties by two approaches: (1) we use a numerical model to simulate the structure of allophane aggregates. The algorithm is based on a cluster-cluster aggregation model. From the simulated data, we derived the pore volume, specific surface area, tortuosity, permeability, and diffusion. We show that transport properties strongly decrease because of the presence of allophane. (2) The fractal approach. We characterize the fractal features (size of the fractal aggregate, fractal dimension, tortuosity inside allophane aggregates) and we calculate that transport properties decrease of several order ranges inside the clay aggregates. These poor transport properties are important parameters to explain the poor accessibility to pollutants in volcanic soils and should be taken into account by future decontamination process. We conclude that for Andosols, this inaccessibility could render inefficient some of the methods proposed in the literature.
B Prado - One of the best experts on this subject based on the ideXlab platform.
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Impacts of land use on hydrodynamic properties and pore architecture of volcanic soils from the Mexican Highlands
Soil Research, 2019Co-Authors: Celine Duwig, Patrice Delmas, B Prado, Anne-julie Tinet, N. Dal Ferro, J. P. Vandervaere, Hervé Denis, P. Charrier, A. Gastelum Strozzi, Francesco MorariAbstract:Volcanic soils are important resources because of their unique mineralogical and physical characteristics, and allophanic Andosols represent some of the world’s most fertile soils. However, their unique properties can be lost when cultivated. Most soils in the Central Valley, Mexico, are derived from volcanic materials. This valley encompasses one of the largest water supply systems in the world by volume, but is affected by soil degradation and deforestation. Sustainably managing volcanic soils requires understanding how land use affects their hydrodynamic properties. Gas adsorption and mercury intrusion porosimetry, water retention curves, tension infiltrometry and X-ray tomography were used to describe pore structure characteristics. Two volcanic soils (one Andosol and one derived from indurated tuff – Tepetates), three land uses (maize monoculture, maize–wheat rotation and fallow) and two horizons (Ap and A2 for maize monoculture and maize–wheat rotation) were studied. Tillage affected topsoil by increasing the sand fraction by 38% and decreasing total porosity and macroporosity by 23% and 40% respectively. Macropore size was reduced and the number of isolated macropores was higher in the tilled layer under maize, compared with untilled subsoil. The plot under maize–wheat rotation had lower allophane content, and saturated hydraulic conductivity was reduced by nearly an order of magnitude and water retention by half, compared with maize and fallow plots. Compared with Andosols, Tepetates showed differences in mineralogical composition with lower contents of amorphous compounds and in its porous network characteristics with twice the total and percolating macroporosity compared with the maize plot. Its high content of organic carbon (3.5%) seemed beneficial for its hydrodynamic properties. Sustainable agricultural management of these volcanic soils requires reducing mechanised tillage, avoiding periods when soil is bare, not applying maize–wheat rotation and applying maize–fallow rotation allowing natural vegetation growth.
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transport sorption and degradation of atrazine in two clay soils from mexico andosol and vertisol
Geoderma, 2014Co-Authors: B Prado, Celine Duwig, Claudia Hidalgo, Karin Muller, L Mora, Elias Raymundo Raymundo, Jorge D EtcheversAbstract:Although atrazine has been banned in the European Union, it is still one of the most widely used herbicides in the world. It is has been detected in surface and groundwater and has been shown to be associated with major human health problems. Atrazine fate in the environment, e.g. sorption, leaching and degradation depends, inter alia, on soil characteristics. Independent static and dynamic experiments were conducted to identify and uncouple the processes governing the fate of atrazine. Two agricultural soils from Mexico with contrasting characteristics in terms of organic matter content and degree of decomposition as well as clay types were selected. Soil organic matter was the main sorbent for atrazine, followed by montmorillonite clays in the Vertisol, and iron oxides and allophanes in the Andosol. Humic acids were predominant in the Andosol's organic matter and favored atrazine sorption, compared to more recalcitrant organic matter such as humin fractions in the Vertisol. Atrazine mobility was enhanced because of the occurrence of preferential flow in the upper layer of the Vertisol and because of the formation of mobile complexes between dissolved organic carbon and atrazine in the Andosol. Our detailed soil characterization and the independent sorption, degradation and transfer experiments allowed identifying the main processes affecting atrazine's fate in the two contrasting soils: In the Vertisol, preferential flow was enhanced because of the lower affinity of the soil's organic matter for atrazine compared to the Andosol. The application of atrazine to Vertisol soils poses a higher risk for groundwater contamination than its application to Andosols.
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image processing based study of soil porosity and its effect on water movement through andosol intact columns
Agricultural Water Management, 2009Co-Authors: B Prado, Patrice Delmas, P Morales, Jason James, J. Marquez, Celine Duwig, Jorge D EtcheversAbstract:The soil pore network and marcoporosity are important factors affecting water and solute transport. The transfer of contaminants to water resources is of particular importance in the Valle de Bravo watershed as it provides 10% of the drinking water for the 20 million inhabitants of Mexico City. This watershed is composed mainly of Andosols with unique mineralogical and physical characteristics. Soil porosity is usually examined on thin sections, using various image analysis techniques. We propose a novel methodology combining image analysis and a displacement experiment to study relationships between soil structure and water tracer transport parameters. H218O displacement experiments were conducted through intact soil columns sampled at three depths from a representative cultivated Andosol profile. The soil structure and pore characteristics were obtained by image analysis on thin sections obtained from each column at the end of the displacement experiment. The total 2D porosity (for pores larger than 50[mu]m) varied from 80% of the total section area in the topsoil to around 60% in the subsoil. Tubular pores were the most abundant in the soil profile, but ploughing of the topsoil had destroyed sections of these pores and replaced them with packing pores. Water transport in the intact subsoil columns was always in physical non-equilibrium, showing the existence of preferential flow pathways. In the topsoil, one column out of three showed no preferential flow, demonstrating that soil ploughing also homogenised pore connections. Pore connectivity was larger in the ploughed topsoil than in their deeper soil horizon counterparts. Our methodology offers a 2D quantitative characterisation of the macroporous network at 50[mu]m resolution and the determination of water transport parameters on the same intact soil samples. 3D characterisation of soil porosity using X-ray computed tomography (CT) gives a better picture of pore connection but usually has lower spatial resolution and a larger cost.