Rosa M. Poch

Pore space characteristics as indicators of soil behaviour in gypsiferous soils

Abstract In order to study the physical properties of gypsiferous soils (Gypsic Xerochrepts and Typic Xerofluvents) from an irrigated semi-arid area in Catalonia (NE Spain) and their relationships to their pore characteristics, twenty horizons with gypsum contents ranging between 0 and 90% were sampled for micromorphological and physical analyses. The micromorphological study consisted of thin section description and of image analysis of uncovered thin sections of samples impregnated with a UV-fluorescent dye. Eight fields of each horizon were studied. Two images were obtained from each field (2.1×3.1 cm 2 ): one illuminated with incident UV-light and the other with transmitted white light. Image processing with an IBAS-system allowed measurement of the geometric characteristics of three types of objects: actual pores (eq. diam.>100 μm), transparent objects infilled or not with gypsum and pores located in these transparent objects. The physical characteristics of the same horizons considered in the study were the water-characteristic curves and the saturated hydraulic conductivity. Although differences in total porosity (between 6 and 16%) are not related to other properties, an increase of gypsum content leads in the studied horizons to the replacement of large pores by smaller packing pores between gypsum crystals in infillings, which are interconnected and do not reduce saturated hydraulic conductivity. Available water is affected by the degree of mixing of the gypsum infillings with the groundmass, besides the crystal size distribution. The results stress the importance of pore clogging by gypsum in these materials as a major constraint for root development, as well as the need of describing the type of gypsum accumulation when assessing the suitability of these soils for plant growth.

Effects of soil and climatic conditions on grape ripening and wine quality of Cabernet Sauvignon.

The effects of climatic conditions and soil type on grape ripening and wine quality were studied for the period 2003–2005, in two Cabernet Sauvignon vineyards under the same climate but on very distinct soils. Climate effect was estimated by studying annual variations. Climatic conditions and soil had overall a significant effect on grape ripening. The effects of soil and climate could be explained mainly by their influence on plant water availability status. Soil type appeared to be determining wine phenolic composition, and related wine tasting characteristics.

A Soil Toposequence Characterization in the Irrigable Lands – Protected Area Contact Zone of El Basal, NE-Spain

The Central Ebro Valley, one of the most arid regions of Europe, has one of the longest histories of continuous and sustainable irrigation within Europe. Despite this sustainable outcome, the further expansion of irrigation into areas that have less favorable soil conditions produces unfavorable results and environmental problems. A representative soil toposequence of currently rainfed agricultural land, located very close to El Basal protected area, has been characterized in order to get information on the soils and to assess their capacity to be irrigated. The studied toposequence comprises three different landforms, a structural platform, a depression, and a step which links them; in these landforms soil profiles were described, analyzed, and classified using standard methodologies. The soil properties and their stages of pedogenic evolution are closely related to their topographic position. Petric Calcisols on the structural platform and Leptic Regosols on the step, both with very shallow rooting depth, give way to a series of salt-affected soils in the depression, such as Hypersalic Solonchak or Salic Solonetz. These severely salt-affected soils, which are included in irrigation plans, have the severe potential to limit agricultural management and plant production; moreover, their proximity to the protected area of El Basal, which includes a saline wetland, is inadvisable due to the probable changes in water and nutrient cycles. For these reasons, a buffer zone around the protected area is proposed. Moreover, the soil toposequence shows a great pedodiversity that should be considered as adding value to the recognized biodiversity of El Basal area.

10 – Gypsic Features

Publisher Summary Gypsic features in soils and sediments are composed of gypsum (CaSO4·2H2O), a mineral with rather low solubility, or they are at least related to gypsum formation. Gypsum is formed when Ca2+ and SO42− concentrations in the soil are high. These ions can come from the dissolution of calcium sulphates contained in rocks in the catchment, but they can also be separately derived from the alteration of limestone, carbonates of biological origin and sulphide-bearing formations. After the development of gypsum crystals in soils and sediments, they can be transported by wind, producing aeolian gypsiferous or gypseous parent materials. Gypsum, both inherited and pedogenic, is most abundant in soils under arid or semi-arid climates, because evaporative concentration is generally required for its formation and because it is easily leached in humid climates.

Rehabilitation of Semi-Arid Coal Mine Spoil Bank Soils with Mine Residues and Farm Organic By-Products

A method of rehabilitating coal mine soils was studied under the conditions of a semi-arid climate, lack of topsoil but availability of farm by-products in NE Spain. The objectives of the research were to assess a new method in order to achieve a suitable substrate for the establishment of native vegetation, to evaluate environmental impacts associated with the reclamation process, and to determine the time necessary to integrate the treated area into the surrounding environment. Eight plots (10 × 35 m2) were established in September 1997. Substrate combinations of two types of mine spoil (coal dust and coarse-sized material), two levels of pig slurry (39 and 94 Mg ha−1dry-wt), and cereal straw (0 and 15 Mg ha−1) were applied. Monitoring of select physical and chemical soil properties and vegetation characteristics was performed from 1997 until 2005. The bulk density and the saturated hydraulic conductivity measured did not limit plant development and water availability. Initial substrate salinity (1.37 S m−1) decreased with time and in the long term did not limit plant colonization to salinity-adapted species. Initial nitrate concentration was 298 mg kg−1, but was reduced significantly to acceptable values in 3 years (55 mg kg−1) and the measured pH (7.6) was maintained at the level of initial spoil values. Vegetation cover reached up to 90%. In the treated area, spontaneous vegetation cover (15 to 70%) colonized the nonsown areas widely. In the medium term, vegetation cover tended to be higher in plots with a thicker layer of coal dust material and the higher slurry rate. Soil rehabilitation and environmental reintegration, taking into account soil and vegetation indicators, was possible in the studied area with low cost inputs using residual materials from mining activities and animal husbandry by-products.

Soil Evolution Along a Toposequence on Glacial and Periglacial Materials in the Pyrenees Range

Data from eight selected soils located in the La Cerdanya basin (Catalan Pyrenees, Spain) are presented in this study in order to elucidate soil forming processes throughout the Quaternary on glacial and periglacial deposits, at altitudes -between 1130 and 2390m. The soils are classified as Umbrisols, Podzols, Arenosols, Regosols, and Luvisols (FAO/ISRIC/IUSS 2006) and Dystrocryepts, Dystrudepts, Fragiorthods, Udalfs (Pale-, Fragi- and Haplo-) and Ustorthents (Soil Survey Staff 1999). The present moisture and temperature regimes are ustic and mesic in the low altitude soils and udic and frigid/cryic in the high altitude soils. The parent materials of the soils are silicate rock end deposits and consist of lateral moraine tills, slope deposits affected by present-day periglacial processes and fluvio-glacial materials at the bottom of the sequence. The soil forming processes in the area relate to the climate changes during the Pleistocene and Holocene, lithology, altitude, and local hydrological conditions. They consist of in-situ deep weathering of granites, organic matter accumulation, fragipan and clay formations, illuviation, and podzolization. The soils have morphological evidences of the past permafrost of the glacial periods, such as the silt and fine sand cappings, lamellar Bt horizons, vesicular structures, and abundant redoximorphic features, which are inherited from moister conditions, probably during the wet interglacial periods. The clay minerals of the soils are mainly illitic, with some kaolinite and smectite in the valley bottom. Chlorite is the dominant clay mineral at higher altitudes (due to mica weathering), whereas hydromica, kaolinite, and halloysite were found in the lower altitudes, due to feldspar weathering. The high mineral weathering and clay illuviation in soils of the lower altitudes indicate that the degree of erosion of the upslope soils have probably been very intense. On upslope soils, the accumulation of organic matter, with clay minerals formation and podzolisation have lead to the development of umbric, cambic, and spodic horizons, whose formation are probably still active at present.

HOW SOIL FORMING PROCESSES DETERMINE SOIL-BASED VITICULTURAL ZONING

The aim of this study was to elucidate the soil forming processes of representative vineyard soils, and to discuss the implications on a soil-based viticultural zoning at very detailed scale. The study area is located in Priorat, Penedes and Conca de Barbera viticultural areas (Catalonia, North-eastern Spain). The studied soils belong to representative soil map units determined at 1:5,000 scale, according to Soil Taxonomy classification. The soil forming processes, identified through morphological and micromorphological analyses, have significant effects on some soil properties. For example, the different processes of clay accumulation in soils developed from granodiorites in Priorat or gravel deposits in Conca de Barbera, are primarily responsible for significant differences in clay content, available water capacity and cation exchange capacity. These soils properties, especially those related to soil moisture regime, have a direct influence on vineyard management and grape quality. However, soil forming processes are not always reflected on soil classification, especially in soils modified by man. We show that climate or geology alone cannot be used in viticultural zoning at very detailed scale, unless soil forming processes are taken into account.

Paleoclimatic implications of micromorphic features of a polygenetic soil in the Monegros Desert (NE-Spain) .

Los edaforrasgos son el resultado de procesos y factores de formacion, por lo que su presencia nos da informacion sobre los cambios ambientales que han tenido lugar con la evolucion del suelo. El objetivo de este trabajo es proporcionar un modelo de interpretacion de un suelo policiclico en el Desierto de Monegros (Cuenca del Ebro, NE-Espana) y relacionarlo con los cambios ambientales a lo largo del Cuaternario. Para lograr este objetivo se describen las propiedades fisicas, quimicas, mineralogicas y micromorfologicas de este perfil. La carbonatacion es evidente en todos y cada uno de los horizontes del perfil. En la parte superior, un grueso horizonte petrocalcico presenta una estructura laminar con capas de micrita y esparita, que a veces forman pendents. Hacia su base, estas capas laminares relativamente puras, micriticas, se intercalan con nodulos orticos de micrita. Por debajo del horizonte petrocalcico aparecen revestimientos y rellenos de calcita microcristalina en antiguos canales junto a nodulos blandos, geodicos (horizonte calcico, Bkc), registro de un proceso de acumulacion in situ. Otro horizonte con nodulos orticos de calcita, impregnativos y difusos se describen en la parte inferior del perfil (Ckc). Entre ambos horizontes calcicos nodulares se encuentran horizontes argicos recarbonatados con gruesos nodulos orticos de micrita densa, superpuestos a edaforrasgos texturales (Btkc y Btk). Los microedaforrasgos texturales encontrados en el horizonte argico son de dos tipos: (1) intercalaciones de arcilla laminada en paquetes, no asociadas con poros actuales o pasados y (2) microlaminaciones de arcilla y limo recubriendo las paredes de poros, orientados debilmente. Asociados a estos rasgos texturales aparecen edaforrasgos de reduccion: (1) hipo y cuasi-revestimientos de oxidos de manganeso alrededor de canales de poros y grietas, y (2) nodulos dendriticos, de oxidos de manganeso y hierro, dentro de agregados. La combinacion de los edaforrasgos y horizontes descritos permiten clasificar el suelo mas antiguo como un Luvisol calcico, sobre el que se desarrollo un Calcisol haplico, ambos sellados por un Calcisol petrico. Esta secuencia de perfiles es una evidencia de fluctuaciones en las condiciones paleohidrologicas a lo largo del Pleistoceno, combinada con una creciente aridez en el semiarido Valle del Ebro.