Buried palaeosols of NW Sardinia (Italy) as archives of the Late Quaternary climatic fluctuations

A multi-disciplinary approach was performed to investigate two compound geosols included between wind-blown deposits at the top, and interglacial (MIS 5) beach sediments at the bottom, located along the Alghero coast (North-western Sardinia, Italy). A sedimentological and morphological study was carried out on the profile in the field, and samples collected on the main pedomembers were subjected to several laboratory analyses, consisting of physical and chemical determinations on bulk samples, mineralogy (XRD), micromorphology on undisturbed samples (thin Section, SEM), and EDAX-micro probe analyses. Dating was performed by means of Optically Stimulated Luminescence (OSL). The studied geosols show the evidence of a complex pedosedimentary evolution. Around 80 to 70. ka the lower geosol underwent weathering and clay illuviation (wet and warm conditions), followed by calcification-recalcification processes (dry-contrasted), and finally by strong bioturbation. Around 70. ka the onset of the glacial period (MIS 4) is marked by the deposition of a sand dune, capping the lower geosol. These results indicate that the coastal area of the central Mediterranean kept the relatively warm conditions typical of the interglacial climate for most of the Early Würm and reached cold conditions only at about 70. ka, possibly in relation to the rapid cooling of the Heinrich event H7. The upper geosol developed on colluvial material including abundant pedorelicts and reddish earth material, deposited around 50. ka. Before being buried by aeolian sand around 43. ka, this deposit underwent pedogenesis phases possibly associated to Middle Würm interstadial events, indicating that in the study area these events were intense enough to influence pedogenesis. © 2014 Elsevier B.V

Data fusion techniques for delineation of site-specific management zones in a field in UK

Fusion of different data layers, such as data from soil analysis and proximal soil sensing, is essential to improve assessment of spatial variation in soil and yield. On-line visible and near infrared (Vis-NIR) spectroscopy have been proved to provide high resolution information about spatial variability of key soil properties. Multivariate geostatistics tools were successfully implemented for the delineation of management zones (MZs) for precision application of crop inputs. This research was conducted in a 18 ha field to delineate MZs, using a multi-source data set, which consisted of eight laboratory measured soil variables (pH, available phosphorus (P), cation exchange capacity, total nitrogen (TN), total carbon (TC), exchangeable potassium (K), sand, silt) and four on-line collected Vis-NIR spectra-based predicted soil variables (pH, P, K and moisture content). The latter set of data was predicted using the partial least squares regression (PLSR) technique. The quality of the calibration models was evaluated by cross-validation. Multi-collocated cokriging was applied to the soil and spectral data set to produce thematic spatial maps, whereas multi-collocated factor cokriging was applied to delineate MZ. The Vis-NIR predicted K was chosen as the exhaustive variable, because it was the most correlated with the soil variables. A yield map of barley was interpolated by means of the inverse distance weighting method and was then classified into 3 iso-frequency classes (low, medium and high). To assess the productivity potential of the different zones of the field, spatial association between MZs and yield classes was calculated. Results showed that the prediction performance of PLSR calibration models for pH, P, MC and K were of excellent to moderate quality. The geostatistical model revealed good performance. The estimates of the first regionalised factor produced three MZs of equal size in the studied field. The loading coefficients for TC, pH and TN of the first factor were highest and positive. This means that the first factor can be assumed as a synthetic indicator of soil fertility. The overall spatial association between the yield classes and MZs was about 40 %, which reveals that more than 50 % of the yield variation can be attributed to more dynamic factors than soil parameters, such as agro-meteorological conditions, plant diseases and nutrition stresses. Nevertheless, multivariate geostatistics proved to be an effective approach for site-specific management of agricultural fields

An anthroscape from Morocco: Degraded rangeland systems and introduction of exotic plant material and technology

Fodder shrub plantations (Atriplex nummularia) were extensively introduced to rehabilitate degraded rangeland and to mitigate desertification in the Rural Municipality of Ouled Dlim (Marrakech Province, Morocco). The original rural landscape, characterised by sparse or absent natural vegetation cover due to a long history of intense grazing activities, has been deeply modified during the last decade by these agroforestry interventions. The purpose of this contribution is to describe the occurred environmental changes under the perspective of the Anthroscape concept, by giving emphasis to the description of the Anthroscape units affected by the plantations and to the geo-pedological processes that influenced the technical success obtained by the interventions. Some critical aspects and possible scenarios of the future evolution of the anthroscapes are also discussed. © Springer-Verlag Berlin Heidelberg 2011

Microstructure and palygorskite neoformation in pedogenic calcretes of central Morocco

The aim of this research was the micromorphological and mineralogical characterization of calcrete outcrops located in central Morocco, with particular focus on microstructure development and palygorskite formation processes. Two study sites in the Al Haouz Plain (ca 30 km west to Marrakech city) were identified, in an area dominated by Quaternary sedimentary formations including layers cemented by carbonate and widespread calcareous crusts at the surface. The calcrete samples were examined by means of polarizing microscopy from thin sections, scanning electron microscopy / energy-dispersive X-ray spectroscopy (SEM/EDX) from undisturbed samples, and X-ray diffraction (XRD) methods. The matrix of the calcrete material cementing the schist fragments composed of abundant calcite was associated mainly with palygorskite, quartz, and to a lesser extent illite/mica, feldspar, and chlorite. SEM observations indicated that palygorskite mainly occurred as fibres, fibre bundles and networks mainly grown on and/or enclosing calcite rhombohedrons. The EDX spectra of the palygorskite fibres exhibited strong silicon (Si) peaks followed by Al, Mg and Fe peaks. The EDX analysis of calcite rhombohedric crystals exhibited a strong Ca peak, followed by weak peaks of Si, Mg, Al and Fe possibly due to nearby or overlapped palygorskite crystals. One main palygorskite neoformation process was described. Palygorskite was authigenically formed (neoformed) during and after precipitation of calcite from percolating soil solutions in a near-surface setting. Peculiar sub-rounded microstructural units, here designated as pedogenic ooids/pisoids (according to the size), were determined in the matrix of the studied calcretes, associated to pendants and clay-rich rims surrounding them. © 2017 Elsevier B.V