The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Nilda Mabel Amiotti - One of the best experts on this subject based on the ideXlab platform.
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sampling scheme optimization to map soil depth to Petrocalcic Horizon at field scale
Geoderma, 2017Co-Authors: Marisa Domenech, Mauricio Castrofranco, Jose Luis Costa, Nilda Mabel AmiottiAbstract:Abstract Soil depth has played a key role in the development of soil survey, implementation of soil-specific management and validation of hydrological models. Generally, soil depth at field scale is difficult to map due to complex interactions of factors of soil formation at field scale. As a result, the conventional sampling schemes to map soil depth are generally laborious, time consuming and expensive. In this study, we presented, tested and evaluated a method to optimize the sampling scheme to map soil depth to Petrocalcic Horizon at field scale. The method was tested with real data at four agricultural fields localized in the southeast Pampas plain of Argentina. The purpose of the method was to minimize the sample dataset size to map soil depth to Petrocalcic Horizon based on ordinary cokriging, five calibration sample sizes (returned by Conditioned Latin hypercube –cLHS-), and apparent electrical conductivity (ECa) or elevation as variables of auxiliary information. The results suggest that (i) only 30% of samples collected on a 30-m grid are required to provide high prediction accuracy (R2 > 0.95) to map soil depth to Petrocalcic Horizon; (ii) an independent validation dataset based on 50% of the samples on a 30-m grid is adequate to validate the most realistic accuracy estimate; and (iii) ECa and elevation, as variables of auxiliary information, are sufficient to map soil depth to Petrocalcic Horizon. The method proposed provides a significant improvement over conventional to map soil depth and allows reducing cost, time and field labour. Extrapolation of the results to other areas needs to be tested.
Jose Luis Costa - One of the best experts on this subject based on the ideXlab platform.
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Modelling effective soil depth at field scale from soil sensors and geomorphometric indices
Acta Agronómica, 2017Co-Authors: Mauricio Castro Franco, Marisa Domenech, Jose Luis Costa, Virginia AparicioAbstract:The effective soil depth (ESD) affects both dynamic of hydrology and plant growth. In the southeast of Buenos Aires province, the presence of Petrocalcic Horizon constitutes a limitation to ESD. The aim of this study was to develop a statistic model to predict spatial patterns of ESD using apparent electrical conductivity at two depths: 0-30 (ECa_30) and 0-90 (ECa_90) and geomorphometric indices. To do this, a Random Forest (RF) analysis was applied. RF was able to select those variables according to their predictive potential for ESD. In that order, ECa_90, catchment slope, elevation and ECa_30 had main prediction importance. For validating purposes, 3035 ESD measurements were carried out, in five fields. ECa and ESD values showed complex spatial pattern at short distances. RF parameters with lowest error (OOBerror) were calibrated. RF model simplified which uses main predictors had a similar predictive development to it uses all predictors. Furthermore, RF model simplified had the ability to delineate similar pattern to those obtained from in situ measure of ESD in all fields. In general, RF was an effective method and easy to work. However, further studies are needed which add other types of variables importance calculation, greater number of fields and test other predictors in order to improve these results.
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sampling scheme optimization to map soil depth to Petrocalcic Horizon at field scale
Geoderma, 2017Co-Authors: Marisa Domenech, Mauricio Castrofranco, Jose Luis Costa, Nilda Mabel AmiottiAbstract:Abstract Soil depth has played a key role in the development of soil survey, implementation of soil-specific management and validation of hydrological models. Generally, soil depth at field scale is difficult to map due to complex interactions of factors of soil formation at field scale. As a result, the conventional sampling schemes to map soil depth are generally laborious, time consuming and expensive. In this study, we presented, tested and evaluated a method to optimize the sampling scheme to map soil depth to Petrocalcic Horizon at field scale. The method was tested with real data at four agricultural fields localized in the southeast Pampas plain of Argentina. The purpose of the method was to minimize the sample dataset size to map soil depth to Petrocalcic Horizon based on ordinary cokriging, five calibration sample sizes (returned by Conditioned Latin hypercube –cLHS-), and apparent electrical conductivity (ECa) or elevation as variables of auxiliary information. The results suggest that (i) only 30% of samples collected on a 30-m grid are required to provide high prediction accuracy (R2 > 0.95) to map soil depth to Petrocalcic Horizon; (ii) an independent validation dataset based on 50% of the samples on a 30-m grid is adequate to validate the most realistic accuracy estimate; and (iii) ECa and elevation, as variables of auxiliary information, are sufficient to map soil depth to Petrocalcic Horizon. The method proposed provides a significant improvement over conventional to map soil depth and allows reducing cost, time and field labour. Extrapolation of the results to other areas needs to be tested.
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effect of no tillage on some soil physical properties of a structural degraded Petrocalcic paleudoll of the southern pampa of argentina
Soil & Tillage Research, 2000Co-Authors: Laura Ferreras, Jose Luis Costa, Fernando O Garcia, C PecorariAbstract:Soil structural deterioration from continuous cropping systems can adversely affect crop development. Conservation tillage systems are useful to control soil degradation, but may lead to excessive soil compaction, negatively impacting crop growth. Physical measurements were made during 1994 on a Chernozemic loam soil (Petrocalcic Paleudoll) with a Petrocalcic Horizon at a depth of 1.2 m in Balcarce (Buenos Aires, Argentina). The experiment started in 1992 with wheat (Triticum aestivum L.), followed in 1993 with soybean (Glycine max. (L.) Merr.) and in 1994 with wheat again. The soil had been previously cultivated for 25 years and presented structural degradation (40% of the optimum value). The aim of the study was to evaluate the effect of two tillage systems: conventional tillage (CT) and no-tillage (NT) on soil physical properties and to determine soil physical factors related to reduced growth of wheat under NT. Soil bulk density in the 3‐8 and 15‐20 cm layers was measured by the cylinder and the paraffin methods. There were no significant differences between treatments (P0.05). Mechanical resistance measured by the cone penetrometer at emergence gave the following values (P0.05): NT: 1.6 MPa, CT: 1.1 MPa at 5‐10 cm depth; NT: 1.6 MPa, CT: 1.0 MPa at 10‐15 cm depth; and NT: 1.3 MPa, CT: 0.9 MPa at 15‐20 cm depth. The function of pore size distribution determined by the water desorption method was significantly different between tillage systems (P0.05). The volume of pores with a diameter larger than 20 mm was greater under CT than under NT (CT: 26.1%, NT: 16.8%). Structural stability as measured by both dry and wet sieving was not significantly different between treatments (P0.05). Plots under CT and NT had low stability indexes (NT: 30%, CT: 26%), showing a deterioration of soil structure. The saturated hydraulic conductivity determined by a constant head technique was significantly lower (P0.05) in NT than in CT plots (NT: 3.510 ˇ7 ms ˇ1 , CT: 10.910 ˇ7 ms ˇ1 ). Soil water content in the topsoil measured by neutron probe was higher for NT in the early in the growth season. From anthesis to physiological maturity no significant difference (P0.05) in soil water content was found between tillage systems. Data suggest that increased soil mechanical resistance under NT can decrease growth of wheat roots and reduce dry matter accumulation and wheat yield. # 2000 Elsevier Science B.V. All rights reserved.
Mike Leeder - One of the best experts on this subject based on the ideXlab platform.
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Reconstructing the ancestral (Plio-Pleistocene) Rio Grande in its active tectonic setting, southern Rio Grande rift, New Mexico, USA
Sedimentology, 2000Co-Authors: Marta Pérez-arlucea, Greg H. Mack, Mike LeederAbstract:Deposits of the ancestral Rio Grande (aRG) belonging to the Camp Rice Formation are preserved and exposed in the uplifted southern portion of the Robledo Mountains horst of the southern Rio Grande rift. The sediments are dated palaeomagnetically to the Gauss chron (upper Pliocene). The lower part of the succession lies in a newly discovered palaeocanyon cut into underlying Eocene rocks whose margins are progressively onlapped by the upper part. Detailed sedimentological studies reveal the presence of numerous river channel and floodplain lithofacies, indicative of varied deposition in channel bar complexes of low-sinuosity, pebbly sandbed channels that traversed generally dryland floodplains and shifted in and out of the study area five times over the 1 Myr or so recorded by the succession. Notable discoveries in the deposits are: (1) complexes of initial avulsion breakout channels at the base of major sandstone storeys; (2) common low-angle bedsets ascribed to deposition over low-angle dunes in active channels; (3) palaeocanyon floodplain environments with evidence of fluctuating near-surface water tables. Sandbody architecture is generally multistorey, with palaeocurrents indicative of funnelling of initial avulsive and main fluvial discharge from the neighbouring Mesilla basin through a narrow topographic gap into the palaeocanyon and out over the study area. An avulsion node was evidently located at the stationary southern tip to the East Robledo fault during Gauss times, with aRG channels to the north flowing close to the fault and preventing fan progradation. Subsequent Matuyama growth of the fault caused (1) deposition to cease as the whole succession was uplifted in its footwall, (2) development of a thick Petrocalcic Horizon, and (3) fan progradation into the Mesilla basin. Parameters for the whole aRG fluvial system are estimated as: active single channels 2 m deep and 25 m wide; valley slope 0.24-0.065°; maximum mean aggradation rate 0.05 mm year-1; major channel belt avulsion interval 200 ky; individual channel recurrence interval 100 ky; minimum bankfull mean flow velocity 1.54 m s-1, minimum single-channel discharge 77 m3 s-1, bed shear stress 22.3 N m-2; and stream power 34.3 W m-2.
Marisa Domenech - One of the best experts on this subject based on the ideXlab platform.
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Modelling effective soil depth at field scale from soil sensors and geomorphometric indices
Acta Agronómica, 2017Co-Authors: Mauricio Castro Franco, Marisa Domenech, Jose Luis Costa, Virginia AparicioAbstract:The effective soil depth (ESD) affects both dynamic of hydrology and plant growth. In the southeast of Buenos Aires province, the presence of Petrocalcic Horizon constitutes a limitation to ESD. The aim of this study was to develop a statistic model to predict spatial patterns of ESD using apparent electrical conductivity at two depths: 0-30 (ECa_30) and 0-90 (ECa_90) and geomorphometric indices. To do this, a Random Forest (RF) analysis was applied. RF was able to select those variables according to their predictive potential for ESD. In that order, ECa_90, catchment slope, elevation and ECa_30 had main prediction importance. For validating purposes, 3035 ESD measurements were carried out, in five fields. ECa and ESD values showed complex spatial pattern at short distances. RF parameters with lowest error (OOBerror) were calibrated. RF model simplified which uses main predictors had a similar predictive development to it uses all predictors. Furthermore, RF model simplified had the ability to delineate similar pattern to those obtained from in situ measure of ESD in all fields. In general, RF was an effective method and easy to work. However, further studies are needed which add other types of variables importance calculation, greater number of fields and test other predictors in order to improve these results.
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sampling scheme optimization to map soil depth to Petrocalcic Horizon at field scale
Geoderma, 2017Co-Authors: Marisa Domenech, Mauricio Castrofranco, Jose Luis Costa, Nilda Mabel AmiottiAbstract:Abstract Soil depth has played a key role in the development of soil survey, implementation of soil-specific management and validation of hydrological models. Generally, soil depth at field scale is difficult to map due to complex interactions of factors of soil formation at field scale. As a result, the conventional sampling schemes to map soil depth are generally laborious, time consuming and expensive. In this study, we presented, tested and evaluated a method to optimize the sampling scheme to map soil depth to Petrocalcic Horizon at field scale. The method was tested with real data at four agricultural fields localized in the southeast Pampas plain of Argentina. The purpose of the method was to minimize the sample dataset size to map soil depth to Petrocalcic Horizon based on ordinary cokriging, five calibration sample sizes (returned by Conditioned Latin hypercube –cLHS-), and apparent electrical conductivity (ECa) or elevation as variables of auxiliary information. The results suggest that (i) only 30% of samples collected on a 30-m grid are required to provide high prediction accuracy (R2 > 0.95) to map soil depth to Petrocalcic Horizon; (ii) an independent validation dataset based on 50% of the samples on a 30-m grid is adequate to validate the most realistic accuracy estimate; and (iii) ECa and elevation, as variables of auxiliary information, are sufficient to map soil depth to Petrocalcic Horizon. The method proposed provides a significant improvement over conventional to map soil depth and allows reducing cost, time and field labour. Extrapolation of the results to other areas needs to be tested.
José Luis Díaz-hernández - One of the best experts on this subject based on the ideXlab platform.
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Isotopic evidence for dolomite formation in soils
Chemical Geology, 2013Co-Authors: José Luis Díaz-hernández, Antonio Sánchez-navas, Emilio ReyesAbstract:Abstract Dolomite formation in soils constitute a particular challenge because of: 1) scant magnesium content in continental environments as opposed to the marine medium, 2) the kinetic problem related to the incorporation of magnesium into the carbonate, and 3) the unknown role of soil dolomites in the global carbon cycle. Pedogenic dolomite formed at deeper soil levels (subsoil) before the development of Petrocalcic Horizon barriers was investigated in a semiarid region of SE Spain (Guadix–Baza basin). Mineralogical characterization, textural relationships and isotopic data concerning soil dolomite, together with the results of a precipitation experiment, provided fuller knowledge of the processes and conditions governing neoformation of dolomite in these soils. In the study case, dolomite enrichment occurs beyond the limit of major biological activity, which coincides with the rooting depth of native perennial plants in the semiarid soils studied. Textural studies reveal the corrosion of inherited dolomite crystals in the upper soil Horizons and the formation of dolomite in depth in relation to a clayey material, composed mainly of smectites. Stable isotope distribution in dolomites throughout the profiles indicates a fractionation with depth. This is explained by the formation of dolomites after the dissolution of the pedogenic calcite. The calcite detected in the subsoil is interpreted here as a precursor of the neoformed dolomites that transport the isotopic signal associated with biological activity of soils to deeper layers. Dolomite formation appears to be favoured by the presence of clay minerals in the precipitation media. Clays retain water during evapotranspiration stages, which drastically change the transport properties of the media and promote the incorporation of Mg into the structure of the neoformed Ca,Mg-carbonate. As confirmed by laboratory experiments, diffusion-controlled crystal-growth processes lead to the formation a precursory “protodolomite” with disordered Ca,Mg distribution from a fluid locally supersaturated in dolomite.
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Comments on “Quaternary landscape evolution and erosion rates for an intramontane Neogene basin (Guadix–Baza basin, SE Spain)” by J.V. Pérez-Peña, J.M. Azañón, A. Azor, P. Tuccimei, M. Della Seta, M. Soligo, (2009) Geomorphology 106, 206–218
Geomorphology, 2012Co-Authors: José Luis Díaz-hernández, Ramon JuliàAbstract:Abstract Perez-Pena et al. (2009) recently estimated erosion rates for an intramontane basin based on the age of the Petrocalcic Horizon developed in the uppermost basin fill surface. This new interpretation contradicts well-established and reliable evidence for the origin of the travertines deposited after this surface was cut by a new exorheic drainage system. We argue that their interpretations are incorrect and that they have ignored much of the previous dating and field geomorphological evidence. Morphological, sedimentary and chronological evidence indicate that the reported incision rates are incorrect.