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Francesco Morari - One of the best experts on this subject based on the ideXlab platform.
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coupling gas transport measurements and x ray tomography scans for multiscale analysis in Silty Soils
Geoderma, 2019Co-Authors: Ilaria Piccoli, Per Schjonning, Mathieu Lamande, Filippo Zanini, Francesco MorariAbstract:Abstract Scale is a key issue in soil studies. The idea that a sample must be of adequate size to embody a specific physical property comes from the representative elementary volume (REV) concept that defines minimum sample size for consistent results. Other approaches to describe soil spatial heterogeneity rely on the fractal dimension concept (FDC), which assumes structure changes with scale continuously, and the discrete hierarchy concept (DHC), which assumes change occurs discretely. This study considered using gas transport measurements combined with X-ray computed micro-tomography (μCT) for multi-scale analyses. Specifically, 24 large (“L cores”, 628.3 cm3) core volume samples were collected from two farms and two soil depths (3–11 cm and 20–28 cm) in northeast Italy. Gas transport parameters, such as air-filled porosity, air permeability, and gas diffusivity, were measured on the original cores and on successively sub-sampled medium (“M cores”, 100.4 cm3) and small (“S cores”, 4.7 cm3) cores. X-ray μCT–derived porosity indices were calculated for the two smaller scales. Soil core sub-sampling resulted in reduced soil gas transport property measurements, especially in the deepest depth when related to large and continuous bio-pore decreases in root channels and wormholes. In small core volumes, the pore network was dominated by small isolated pores, which might obstruct gas diffusion at that scale. All three concepts named above could be reconciled with our data. The limited numbers of samples and observation scales hindered identifying which model described soil spatial heterogeneity best. Finally, our results suggested the importance of considering scale effects on soil physical properties and their measurement consistency.
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challenges of conservation agriculture practices on Silty Soils effects on soil pore and gas transport characteristics in north eastern italy
Soil & Tillage Research, 2017Co-Authors: Ilaria Piccoli, Per Schjonning, Mathieu Lamande, Lorenzo Furlan, Francesco MorariAbstract:Abstract Soil air exchange is one of the most important soil functions that directly impacts on crop productivity and environment. Generally, conservation agriculture (CA) practices are expected to provide improved soil aeration but contrasting texture-related effects were found in the literature. The aim of this study was to evaluate the effect of CA practices on gas transport characteristics in the Silty Soils of the Veneto Region (North-Eastern Italy). In 2010, a field experiment comparing CA practices (no-tillage, cover crop and residues retention) to conventional intensive tillage (IT) system was established in four farms located in the Veneto low plain. In fall 2015, 144 undisturbed 100 cm 3 soil cores where collected at two different layers (3–6.5 cm and 20–23.5 cm) and analysed for air-filled porosity, air permeability, gas diffusivity and soil structure indices derived. Gas transport measurements highlighted low transmission properties of the Silty Soils independently from agronomic management. Both air permeability and relative gas diffusivity showed poor aerated conditions being generally 2 and CA treatments affected the transmission properties only in the coarsest soil studied causing a reduction of air permeability in the deeper layer and relative gas diffusivity in both layers. The CA-induced reduction was related to the tillage effect on soil bulk density and suggested that CA not only affected the air-filled porosity but also continuity and tortuosity characteristics. The poor structural stability of Veneto Soils, particularly the poor soil organic carbon content, could prevent the exploitation of CA practices firstly on soil structure and in turn on gas exchanges. For these reasons further studies elucidating the mechanisms improving soil structural conditions for Silty Soils as those examined in this study are required.
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conservation agriculture had a poor impact on the soil porosity of veneto low lying plain Silty Soils after a 5 year transition period
Land Degradation & Development, 2017Co-Authors: Ilaria Piccoli, Lorenzo Furlan, Carlo Camarotto, Barbara Lazzaro, Francesco MorariAbstract:Conservation agriculture practices have been proposed as a set of techniques for improving soil structure properties and related ecosystem services. This study compared conservation agriculture (CA) practices (no-tillage, cover-crop and residue retention) and conventional intensive tillage system (IT) in order to evaluate their effects on total porosity, pore size distribution, pore architecture and morphology. The experiment was set up in 2010 on four farms of the low-lying Veneto Region plain characterized by Silty Soils. Almost hundred soil samples were collected in 2015 at four depths down to 50 cm layer, and investigated for porosity from micro (0.0074 µm) to macro (2.5 mm) by coupling mercury intrusion porosimetry (MIP) and x-ray computed microtomography (μCT). Indices of soil morphology and architecture were derived by analysing 3D images and MIP pore size curves. Results suggested that Silty Soils of Veneto plain are micro-structured since much (82%) of the porosity ranged between 0.0074 and 30 µm. CA practices positively influenced the ultramicroporosity class (0.1-5 µm) (1.86E-01 vs 1.67E-01 µm3 µm-3) which is strictly linked to soil organic carbon (SOC) stabilization while no effects were observed in x-ray μCT porosity domain (>26 µm). Silty Soils of Veneto plain showed a slow reaction to conservation agriculture because of the poor aggregate stability and low soil organic carbon. However the positive response of the ultramicropore fraction indicates that a virtuous cycle was initiated between SOC and porosity, hopefully leading to well-developed macropore systems and, in turn, enhanced soil functions and ecosystem services.
Ilaria Piccoli - One of the best experts on this subject based on the ideXlab platform.
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coupling gas transport measurements and x ray tomography scans for multiscale analysis in Silty Soils
Geoderma, 2019Co-Authors: Ilaria Piccoli, Per Schjonning, Mathieu Lamande, Filippo Zanini, Francesco MorariAbstract:Abstract Scale is a key issue in soil studies. The idea that a sample must be of adequate size to embody a specific physical property comes from the representative elementary volume (REV) concept that defines minimum sample size for consistent results. Other approaches to describe soil spatial heterogeneity rely on the fractal dimension concept (FDC), which assumes structure changes with scale continuously, and the discrete hierarchy concept (DHC), which assumes change occurs discretely. This study considered using gas transport measurements combined with X-ray computed micro-tomography (μCT) for multi-scale analyses. Specifically, 24 large (“L cores”, 628.3 cm3) core volume samples were collected from two farms and two soil depths (3–11 cm and 20–28 cm) in northeast Italy. Gas transport parameters, such as air-filled porosity, air permeability, and gas diffusivity, were measured on the original cores and on successively sub-sampled medium (“M cores”, 100.4 cm3) and small (“S cores”, 4.7 cm3) cores. X-ray μCT–derived porosity indices were calculated for the two smaller scales. Soil core sub-sampling resulted in reduced soil gas transport property measurements, especially in the deepest depth when related to large and continuous bio-pore decreases in root channels and wormholes. In small core volumes, the pore network was dominated by small isolated pores, which might obstruct gas diffusion at that scale. All three concepts named above could be reconciled with our data. The limited numbers of samples and observation scales hindered identifying which model described soil spatial heterogeneity best. Finally, our results suggested the importance of considering scale effects on soil physical properties and their measurement consistency.
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challenges of conservation agriculture practices on Silty Soils effects on soil pore and gas transport characteristics in north eastern italy
Soil & Tillage Research, 2017Co-Authors: Ilaria Piccoli, Per Schjonning, Mathieu Lamande, Lorenzo Furlan, Francesco MorariAbstract:Abstract Soil air exchange is one of the most important soil functions that directly impacts on crop productivity and environment. Generally, conservation agriculture (CA) practices are expected to provide improved soil aeration but contrasting texture-related effects were found in the literature. The aim of this study was to evaluate the effect of CA practices on gas transport characteristics in the Silty Soils of the Veneto Region (North-Eastern Italy). In 2010, a field experiment comparing CA practices (no-tillage, cover crop and residues retention) to conventional intensive tillage (IT) system was established in four farms located in the Veneto low plain. In fall 2015, 144 undisturbed 100 cm 3 soil cores where collected at two different layers (3–6.5 cm and 20–23.5 cm) and analysed for air-filled porosity, air permeability, gas diffusivity and soil structure indices derived. Gas transport measurements highlighted low transmission properties of the Silty Soils independently from agronomic management. Both air permeability and relative gas diffusivity showed poor aerated conditions being generally 2 and CA treatments affected the transmission properties only in the coarsest soil studied causing a reduction of air permeability in the deeper layer and relative gas diffusivity in both layers. The CA-induced reduction was related to the tillage effect on soil bulk density and suggested that CA not only affected the air-filled porosity but also continuity and tortuosity characteristics. The poor structural stability of Veneto Soils, particularly the poor soil organic carbon content, could prevent the exploitation of CA practices firstly on soil structure and in turn on gas exchanges. For these reasons further studies elucidating the mechanisms improving soil structural conditions for Silty Soils as those examined in this study are required.
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conservation agriculture had a poor impact on the soil porosity of veneto low lying plain Silty Soils after a 5 year transition period
Land Degradation & Development, 2017Co-Authors: Ilaria Piccoli, Lorenzo Furlan, Carlo Camarotto, Barbara Lazzaro, Francesco MorariAbstract:Conservation agriculture practices have been proposed as a set of techniques for improving soil structure properties and related ecosystem services. This study compared conservation agriculture (CA) practices (no-tillage, cover-crop and residue retention) and conventional intensive tillage system (IT) in order to evaluate their effects on total porosity, pore size distribution, pore architecture and morphology. The experiment was set up in 2010 on four farms of the low-lying Veneto Region plain characterized by Silty Soils. Almost hundred soil samples were collected in 2015 at four depths down to 50 cm layer, and investigated for porosity from micro (0.0074 µm) to macro (2.5 mm) by coupling mercury intrusion porosimetry (MIP) and x-ray computed microtomography (μCT). Indices of soil morphology and architecture were derived by analysing 3D images and MIP pore size curves. Results suggested that Silty Soils of Veneto plain are micro-structured since much (82%) of the porosity ranged between 0.0074 and 30 µm. CA practices positively influenced the ultramicroporosity class (0.1-5 µm) (1.86E-01 vs 1.67E-01 µm3 µm-3) which is strictly linked to soil organic carbon (SOC) stabilization while no effects were observed in x-ray μCT porosity domain (>26 µm). Silty Soils of Veneto plain showed a slow reaction to conservation agriculture because of the poor aggregate stability and low soil organic carbon. However the positive response of the ultramicropore fraction indicates that a virtuous cycle was initiated between SOC and porosity, hopefully leading to well-developed macropore systems and, in turn, enhanced soil functions and ecosystem services.
M.c. Sasal - One of the best experts on this subject based on the ideXlab platform.
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A contribution to understanding the origin of platy structure in Silty Soils under no tillage
Soil and Tillage Research, 2017Co-Authors: M.c. Sasal, A.e. Andriulo, Joël Léonard, Hubert BoizardAbstract:Abstract In Silty Soils under no tillage (NT), platy (P) soil structure is widespread and constrains water infiltration. Our objectives were (i) to evaluate how traffic and the presence of crop residues influence P structure development in the field and (ii) to characterize changes in soil structure caused by alternation of wetting and drying (w-d) periods for two topsoil layers of a Silty soil and two compaction levels in the laboratory. The five-year field experiment was carried out on a Typic Argiudoll under NT and the structure of the A horizon was analyzed using visual soil evaluation (VSE) both before and five years after two traffic levels were applied to four crop sequences. The laboratory experiment of w-d cycles was carried out with two disturbed layers of a Typic Argiudoll, which was repacked to achieve two different bulk densities, and the columns were subjected to 5, 10, or 15 w-d cycles. In the field experiment, the P structure was clearly identified by VSE and corroborated by shear strength and bulk density measurements. The proportion of P structure increased until about 50% of the A horizon after 5 years, irrespective of the traffic or presence of crop residues at the expense of the Φ structure proportion. In the laboratory, consecutive w-d cycles caused changes in soil volume, cracking of the soil surface, and formation of P structure of variable thickness up to 20 mm, confirming that alternation of w-d periods can cause structural modification of the Silty soil, in particular horizontally oriented cracks. The number of w-d cycles increased the thickness of the P structure in the upper layer (R2 = 0.55) and in the compacted treatment (R2 = 0.81). The results obtained constitute important progress in the understanding of the evolution of P structure of Silty Soils under NT.
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Platy structure development under no-tillage in the northern humid pampas of Argentina and its impact on runoff
Soil and Tillage Research, 2016Co-Authors: M.c. Sasal, Hubert Boizard, A.e. Andriulo, M.g Wilson, Joël LéonardAbstract:The no-tillage system (NT) is widespread in the Silty Soils of the Argentine Humid Pampas. The aims of this study were i) to characterize the evolution of the structure of the A horizon in the northern Humid Pampas due to conversion to NT, particularly the presence of platy structure and its developmentthrough time, by taking advantage of a chronosequence since conversion to NT; and ii) to evaluate how platy structure extension in the A horizon relates to characteristics of the crop sequences and runoff in a longterm experiment. Thus, the structure of the A horizon of 25 Argiudolls with different NT history was analyzed using a visual structure evaluation (VSE) method (“le profil cultural”). Fourteen natural-rainfall erosion plots with 3.5% slope were used to analyze the relationship between the soil structural state, the crop sequence and runoff. The VSE method allowed us to understand the structure type organization of Silty Soils under NT, highlight the regional extent of a platy structure near the soil surface, and study its evolution and impact on runoff. All the sites analyzed exhibited a horizontal platy structure (2–10 cm thick), mainly developing on the soil surface or right under the granular structure on the soil surface. Under the platy structure, a cF structure was observed in all the sites (30–75% of the A horizon). A relationship was found between the number of consecutive years under NT and the proportion of platy structure. This evolution may result from the combination of an initial development of the platy structure and a late development of a cΓ structure from the soil surface. The results obtained during the five-year period analyzed allowed us to prove that platy structure alters the drainage pattern, restricts water entry into the soil and favors surface runoff according to its proportion in the profile of A horizon.
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Role of the underlying massive soil structure on surface platy structure development under no-tillage in Silty Soils of the argentinean humid pampas
2012Co-Authors: M.c. Sasal, Joël Léonard, A.e. AndriuloAbstract:The generalization of no-tillage (NT) in the Silty Soils of the Argentinean Humid Pampas has led to widespread soil densification (massive structure) and the frequent development of a platy structure layer near the soil surface. Previous findings have shown that exposure of a massive soil structure to wet-dry cycles results in the rapid extension of the platy structure, which has negative consequences on water infiltration and vertical transfer. We used a 25-year NT trial with two contrasted crop sequences (a soybean monoculture and a Maize-Wheat/Soybean succession), which resulted in highly different proportions of platy structure in the A horizon (>50% vs. 300 µm), a higher water transfer rate and a higher aggregate stability. In addition, the most sensitive mechanism of aggregate breakdown was differential swelling during the slow wetting of the soil. The combination of a faster water movement in the Maize-Wheat/Soybean succession and the main role of differential swelling during the slow wetting of the soil for aggregate breakdown suggest that differences in the soil structure of the massive layer on which the platy soil structure develops may be the cause of the observed large difference in the extension of the platy soil layer. Understanding why the massive soil structure properties differ may help maintaining soil properties less favorable to platy soil structure development.
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Is platy soil structure development in the argentinean humid pampas related to traffic and crop residue management?
2012Co-Authors: M.c. Sasal, A.e. Andriulo, Joël LéonardAbstract:In Silty Soils of the Argentinean Humid Pampas cropped under no tillage (NT), platy soil structure is widespread and constrains water entry and transfer into the topsoil. Many authors have attributed this to planes of weakness induced by traffic compaction. The most extensive cropping system has high soybean frequency in the rotation, which results in frequent harvesting during fall on wet Soils only sparsely covered by crop residue. Our objective was to test the hypothesis that traffic and the presence of crop residues influence platy structure development. A five-year field experiment was started in 2005 at INTA Pergamino, Buenos Aires, Argentina, on a Typic Argiudoll which had been cultivated under NT for the previous five years. After initial characterization of the soil structure, two traffic levels (Tf /NTf) were applied to four crop sequences: soybean monoculture, maize-wheat/soybean succession, same succession with residues exportation, bare soil. The soil structural state was assessed using the cultural profile approach, and bulk density, pore size distribution, pore origin distribution, aggregate stability, total C and shear strength were determined for each type of soil structure. At the start of the experiment, platy structure was absent and the topsoil was constituted of 95% of gamma (Γ) and 5% of delta (∆) structures. In crop successions, the top centimeters were dominated by a granular structure, irrespectively of the surface residues cover. The proportion of platy structure then increased until covering about 50% of the A horizon after 5 years, irrespective of the traffic or presence of crop residues, and the Γ structure was proportionally reduced. Soil surface structure evolution under NT was thus marked by the rapid development of platy structure to the detriment o f the Γ structure in all situations analyzed, which suggests that the traffic and the presence of crop residues are not critical factors for platy structure development in Silty Soils of the Argentinean Humid Pampas.
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soil porosity characteristics and water movement under zero tillage in Silty Soils in argentinian pampas
Soil & Tillage Research, 2006Co-Authors: M.c. Sasal, A.e. Andriulo, Miguel Angel TaboadaAbstract:Abstract The objective of this study was to identify pore characteristics (quantity, distribution, stability and orientation of pores) that condition water dynamics under continuous zero tillage (ZT) on Silty Soils of the Argentinian Rolling Pampas. Soil properties were analyzed under continuous chisel plough (CP) and ZT treatments from three trials with different duration and crop sequence. The following soil properties of A horizon were analyzed from 0 to 0.05 and from 0.10 to 0.15 m depths: bulk density, pore size distribution, pore origin distribution, aggregate stability index, infiltration rate and organic matter. Preferred pore orientation was carried out by introducing the sampling cylinders in vertical and horizontal direction and then discriminating by pore size. Total porosity of A horizon under CP was 3.5% higher than under ZT. This could be attributed to macro and mesopores as well as to structural porosity. Aggregates were 30% more stable in ZT than under CP in the top at 0.05 m due to a 21% increase in organic matter. However, infiltration rate was not improved under ZT. Under ZT, there was a tendency of macropores to become orientated in parallel to the soil surface. This horizontal preferential macropore orientation was critical in determining water infiltration. The susceptibility to stratify the structure in the first centimeters of the soil under ZT was attributed to the predominance of soybean in the crop sequence.
Sophie Cornu - One of the best experts on this subject based on the ideXlab platform.
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Location of natural trace elements in Silty Soils using particle-size fractionation.
Geoderma, 2006Co-Authors: Michel Hardy, Sophie CornuAbstract:In Silty material, 80% of the particles range from 2 to 50 μm. Particle-size fractionation within this size range allows determination of the main mineral bearers of natural trace elements (TE) in Silty soil. Three Silty Soils were studied: at Château-Thierry in the Paris Basin, at Muret in the Aquitaine Basin, and at Thann in the Alsace plain. These Soils mainly consist of quartz, alkaline feldspars, plagioclase, micas and chlorite, the quantities of which vary with particle-size as shown by XRD and chemical analyses of major elements. Quartz content increases with increasing particle size, whereas feldspars, micas and chlorites occur mainly in the 2–10, 0.2–2 and < 0.2 μm particle-size fractions, respectively. Cu, Co, Cr, Ni, Zn, Pb and major-element contents were measured; TE values showed a negative correlation with Si and a positive one with Al, related to the absence of TE in quartz. Negative correlations of TE with Na and Ca are interpreted as the absence of TE in alkaline feldspars and plagioclase. TE values correlate with Mg, suggesting that they are present in chlorite and trioctahedral micas. Correlations of TE with K are more complex, K-bearing minerals being K-feldspar and micas. In the < 2 μm fractions, K is lost while TE contents increase. Micas were thus considered to be one of the main TE bearers. As correlation does not pass through zero, other K-bearing minerals such as K-feldspar were considered as TE free. Generally speaking, TE contents increase as particle-size decrease.
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Location of natural trace elements in Silty Soils using particle-size fractionation
Geoderma, 2005Co-Authors: Michel Hardy, Sophie CornuAbstract:Abstract In Silty material, 80% of the particles range from 2 to 50 μm. Particle-size fractionation within this size range allows determination of the main mineral bearers of natural trace elements (TE) in Silty soil. Three Silty Soils were studied: at Château-Thierry in the Paris Basin, at Muret in the Aquitaine Basin, and at Thann in the Alsace plain. These Soils mainly consist of quartz, alkaline feldspars, plagioclase, micas and chlorite, the quantities of which vary with particle-size as shown by XRD and chemical analyses of major elements. Quartz content increases with increasing particle size, whereas feldspars, micas and chlorites occur mainly in the 2–10, 0.2–2 and
Laura Tonni - One of the best experts on this subject based on the ideXlab platform.
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analysis and interpretation of piezocone data on the Silty Soils of the venetian lagoon treporti test site
Canadian Geotechnical Journal, 2011Co-Authors: Laura Tonni, Guido GottardiAbstract:This paper reports the main results of an extensive piezocone testing campaign performed over the last years at the Treporti test site (Venice, Italy) within a long-lasting and comprehensive research project aimed at developing a reliable geotechnical model of the heterogeneous and highly stratified Venetian lagoon basin. The project included the construction of a full-scale vertical-walled cylindrical test bank, together with a detailed monitoring system of surface settlements, pore-water pressures, subsoil strains, and stresses beneath the loaded area. The analysis of the large amount of data thus available, referring to different phases of the loading history, confirms the great potential of piezocone as an in situ testing technique, especially for stratigraphic profiling of the predominantly Silty subsoil of the Venetian lagoon, but at the same time reveals some limitations of widely used empirical correlations for the relevant soil characterization, with special reference to compressibility and conso...
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interpretation of piezocone tests in venetian Silty Soils and the issue of partial drainage
GeoShanghai 2010 International ConferenceShanghai Society of Civil EngineeringChinese Institute of Soil Mechanics and Geotechnical EngineeringAmerican, 2010Co-Authors: Laura Tonni, Guido GottardiAbstract:The paper reports results of an extensive piezocone testing campaign performed at the Treporti Test Site (Venice, Italy) within a long-lasting research project aimed at developing a reliable geotechnical model of the heterogeneous and highly stratified Venetian lagoon subsoil. The analysis and the interpretation of the large amount of piezocone data in terms of compressibility and consolidation properties of the Venetian Silty sediments reveal limitations of standard approaches for the characterization of such intermediate Soils. Potentially dilative behaviour as well as partial drainage effects during cone penetration in silts must be taken in careful consideration in order to derive reliable soil parameters from in-situ measurements. According to recently proposed procedures, a preliminary attempt to assess drainage degree during piezocone tests is finally proposed.
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adapting a generalized plasticity model to reproduce the stress strain response of Silty Soils forming the venice lagoon basin
Soil Stress-Strain Behavior: Measurement Modeling and Analysis Solid Mechanics and Its Applications, 2007Co-Authors: Simonetta Cola, Laura TonniAbstract:A Generalized Plasticity model, originally developed for the analysis of sandy soil behaviour, is modified in order to properly simulate the stress-strain response of a wide class of non-active natural Soils, forming the upper profile of the Venice Lagoon basin. The main modification consists in introducing a state-dependent dilatancy, which allows proper modelling of granular Soils over a wide range of pressures and densities, fulfilling at the same time basic premises of critical state soil mechanics. Moreover, according to recent developments on the isotropic compression of granular Soils, few adjustments are introduced in the plastic modulus expression. The approach is validated by comparing the model predictions with experimental data obtained from drained triaxial compression tests on natural and reconstituted samples of Soils having different fine contents.