Soil Typology Research Articles

Validation of subsampling procedures and granulometry distribution uncertainty assessment in environmental soil analysis

A scheme for validation of subsampling activities and assessment of granulometry distribution uncertainty has been developed. The study has been performed to ensure the representativity of the aliquot, the subsample, selected for the analytical procedure with respect to the field sample and final results. The procedure developed provides an easily accessible empirical method based on repeated measurements. The uncertainty and its consequences on analytical results have been evaluated. Different soil typologies have been tested.

Variability of Soil Types in Wetland Meadows in the South of the Chilean Patagonia

The wetland meadows and pastures (vegas) of the agricultural zone of the Magallanes Region and the Chilean Patagonia are productive and intensively exploited ecosystems. However, there is scarce data about the typology and the physical and chemical properties of the soils that determine the agricultural potential of vegas sites. Sampling of the main horizons of 47 soil profiles was conducted throughout the area. The profiles were described in the field and consequently classified according to the soil typology system of the WRB (IUSS Working Group WRB, 2006). Analyses of bulk and particle densities, capillary water capacity, pH (H2O), pH (CaCl2), texture, organic material, C:N ratio, electrical conductivity, effective cation exchange capacity, N, P, Ca-Mg-K-Na, exchangeable Al, extractable Al, sulfur SO4 2- , B, and micronutrients (Cu-Zn-Mn-Fe) were carried out. The most frequently recorded groups of soil types in the studied vegas were Histosols - peat soils (20 profiles), and Fluvisols (19). Gleysols (3), Vertisols (1), Regosols (3), Solonchaks (1) and Solonetzs (1) were detected with much less frequency. There is also considerable variability in soil properties among and within the groups of soil types. The principal differences between the Histosols and the Fluvisols are the content of organic matter (often peat), pH level (related to the absence/presence of carbonates) and associated soil properties. Fluvisols are more susceptible to salinization under conditions of aridity, whereas the main threat to Histosols is artificial drainage.

Spectral properties and sources of variability of ecosystem components in a Mediterranean semiarid environment

Monitoring changes in soil and vegetation is crucial in fragile Mediterranean semiarid environments. To identify early perturbation warnings using radiometric techniques, the spectral variability of the ecosystem components must be understood and the ranges of their natural variability established. This paper aims to assess the potential of hyperspectral information for analysing spectral variability and to provide guidelines for using spectroscopy to monitor semiarid environments. Spectral field measurements of different soil (volcanic and calcareous), vegetation (esparto and dwarf palm) and natural mixtures (NPV and BSC) were acquired; spectral assessment focused on albedo, spectral shape and absorption bands. Results show high variability of soil background between and within soil typologies. The presence of biotic elements masks the distinctive characteristics between soil typologies, making combination of the VIS-NIR and SWIR regions necessary for correct discrimination and quantification of soil properties. Plant species are discriminated by taking advantage of their spectral properties based on the differences in absorption by chlorophyll, water and lignin. In summer, these differences are more significant, predictably due to their specific survival strategies. Radiometric techniques enable discrimination of ecosystem components, although the high variability of the landscape and subtle differences between components makes it necessary to use high-spectral resolution information.

Distinguishing subalpine soil types using extractible Al and Fe fractions and REE geochemistry

Only a few paleoecological studies have attempted to use the geochemistry of lacustrine sediments to reconstruct the history of soil genesis. The geochemical signatures of modern soils must firstly be determined before using them to investigate lake sediments. Our study explores the geochemical variability between eight subalpine soil profiles from the internal zone of the Alps to find relevant sediment tracers for present-day soils. Based on the concentrations of secondary Al- and Fe-bearing phases, as well as major element and Rare Earth Element (REE) geochemistry, different subalpine soil types can be clearly differentiated in the study area. Although formed in similar geomorphological settings, the soil typologies are diverse: Podzol group soils are developed under old-growing coniferous forest, whereas Cambisols occur under present-day old-meadows. By applying PCA including pedological and geochemical parameters, we can clearly discriminate between Podzol and Cambisol samples, revealing differences that reflect the intensity of chemical weathering. In contrast, deep and surface samples can be distinguished using the degree of physical weathering. The proportions of organic-bound Al and Fe are significantly higher in Podzols, thus providing a sediment tracer to reconstruct the intensity and degree of podzolisation. The increase of Light REE fractionation from the C-horizons to the topsoil horizons is explained in terms of soil processes. The high-field-strength element Nb is used to estimate enrichment or depletion relative to the unweathered parent material. The resulting normalized REE patterns indicate that Podzol profiles are more depleted than Cambisols. Moreover, normalized REE patterns of A- and B w-horizons are similar in the Cambisol profiles, whereas the E- and B s-horizons of Podzols exhibit large variations. Normalized REE patterns may thus provide a precise tracer of the degree of weathering of materials. Hence, we suggest that REE behaviour and soil weathering are clearly related. This study also highlights the effects of millennial-scale agricultural practices on soils, e.g. the eventual depodzolization related to deforestation.

Soil subsampling in environmental sciences: the role of granulometry

Uncertainty associated to analytical results is an issue of major interest for the whole analytical community. A large effort has been made to improve analytical techniques and procedures aimed to achieve a well characterized uncertainty associated with analysis. However, it is becoming increasingly recognised that uncertainty deriving from sampling and subsampling can even dominate the global uncertainty budget. A study on subsampling activities on different soil typologies has been performed by granulometry determinations. The differences between sieving methodologies based on both wet and dry mode have been studied. Subsampling is approached by replicated measurements providing a quantitative assessment of the distribution heterogeneity, a suitable method validation scheme and an empirical determination of uncertainty.

Carbon and nitrogen enhancement in Cambisols and Vertisols by Acacia spp. in eastern Burkina Faso: Relation to soil respiration and microbial biomass

The current study tested the contribution of native Acacia species of the Sudano-Sahelian zone to improving organic carbon and nitrogen level in Cambisols and Vertisols with specific focus on variation in microbial biomass ( C mic), soil basal respiration ( C resp) and metabolic quotient ( qCO 2). The results show enrichment in total organic carbon ( C total), in total nitrogen ( N total) and higher clay content under Acacia canopies as compared to adjacent open grasslands. The relative nutrient concentration in Acacia cover showed an increase in C mic ranging from 203 to 572 μg g −1 whereas in adjacent open grassland it varied from 100 to 254 CO 2–C μg g −1. As a function of C mic ( r = 0.60), C total ( r = 0.70) and N total ( r = 0.70), C resp was higher under Acacia canopies than open grassland and this difference was more pronounced when measured over lengthier incubation periods (10–21 days). A lower qCO 2 under Acacia cover (except for one site) demonstrated a change in microorganisms communities structure and higher substrate use efficiency as compared to open grassland. The results also show that soil texture, as well as vegetation cover, influenced microbial processes. The negative correlation between clay content and carbon mineralization ( C resp/ C total, qCO 2), and positive linear relation between clay and C mic supported the hypothesis that finer soil texture protects soil microbial biomass against degradation and limits organic matter mineralization. The specific effects of soil typology and vegetation cover on C mic and qCO 2 variability were significant, but the greater effects were attributed to vegetation cover.

Local knowledge of soils: the case of contrast in Côte d'Ivoire

Local soil–land typologies and the extent of local soil knowledge are described for two distinct cultures in West Africa's Ivory Coast: the Bété of the equatorial forest zone and the Senufo of the guinea-savanna zone. The Bété, whose soils are under dense forest vegetation, described 11 mutually exclusive soil types. The Senufo, whose soils are more exposed on a guinea-savanna landscape, claimed to have two to three soil types, named for such characteristics as color, floodability, texture, or gravel content. The descriptions of each soil type were compared with statistical analyses of laboratory data of each soil type and a semidetailed land characterization of the area. These scientific views corroborate the Bété view of the soils; the relationship was less clear for the Senufo. Differences in knowledge were more pronounced with differences in age, differences in articulating knowledge, and by individual and cultural interests in the land and agriculture. Local knowledge about land features in relationship to management enriched the local soil typologies. Such information is important to research and extension efforts to improve the use of soils and land resources by their local managers.

Farmers' knowledge of soils and the sustainability of agriculture in a saline water ecosystem in Southwestern Bangladesh

Small holder farmers throughout Bangladesh operate in small but diverse ecosystems and possess a deep intimate knowledge of local soils. They have developed soil management strategies that helped them to attain a high degree of sustainability. In this study, a group of small holder farmers from a village in the saline water ecosystem in southwestern Bangladesh were interviewed to explore the depth of their knowledge of soils. Data collected from a parallel scientific study done in the same village revealed that the village farmers possessed considerable knowledge of local soils, their classification, and management problems. Farmers' typology of soils differed from their scientific classification because of the diversity in objectives and approaches to study the village soils. Despite their lack of knowledge of the soil genesis and morphology and soil chemistry, farmers qualitatively identified major typology, properties, and constraints of topsoil, and have developed strategies through generation-long practical on-farm experiments that helped them to maintain a sustainable agricultural system in the village. Farmers' knowledge of soils is, therefore, a vast resource that should be tapped and incorporated in the national scientific database and utilized in formulating future agricultural development policies.

Relationship between the characteristics of Mediterranean red soils and the age of the geomorphological surfaces in central-western Spain

A study was conducted of the Mediterranean Red soils of a region in Central Western Spain with a goal of describing the relationship between their main characteristics and the age of the geomorphic surfaces over which they have developed. The main macromorphological characteristics of the soils were analyzed, with a statistical study of the analytical data on 70 samples of Mediterranean Red soils. The oldest surfaces contain Palexerults and Ultic Palexeralfs, Calcic Rhodoxeralfs, Calcic—vertic Palexeralfs. Typic Rhodoxeralfs. Typic Palexeralfs, Vertic Haploxeralfs and Typic Haploxeralfs have been observed in a chronosequence on terraces of the River Tormes. The soil typology changes with the age of the surfaces, from soils with a sharp textural contrast at the upper limit of the argillaceous horizon, with a dark red very clayey and very thick Bt horizon (on the oldest surface) to not very thick brown soils without a clear clay illuviation and with a lower content in clay (on the youngest surface). The effect of recent erosion on the morphology of the soils located on a single surface has caused new soils to form superimposed on pre-existing soils.

Typology and genesis of ilimerized soils in the Southeastern Iberian Peninsula

In the Sierra de Carrascoy (Murcia, southeastern Spain), ilimerized soils appear locally with different characteristics from those of the dominant soils. These ilimerized soils are relicts of more stable geomorphological surfaces. Four representative profiles were studied for evaluating their pedogenetic processes and to classify them typologically. Analytical determinations were made of organic carbon, total nitrogen, calcium carbonate equivalent, pH, cation exchange capacity, electrical conductivity, and particle size. Determinations were made of free iron oxide extracted with sodic hydrosulfite, and total iron, silicon, and aluminum oxides. The profiles are of a A‐Bt‐Ck or A‐Bt‐R type with a pronounced reddish color (2.5YR or 5YR). The soils have an average organic matter content of 19.6–44.5 g kg−1 in the surface horizons and, in general, are totally decarbonated. The cation exchange capacity is highest in the argillic horizons (16.9–25.0 cmole kg−1), and their electrical conductivity is generally low...

On the potential of basing an ecological typology of aquatic sediments on the nematode fauna: An example from the River Rhine

In Dutch river sediments nematodes can occur in high numbers; azoic seediments are as yet unknown. In aseries of samples takenj from the river Rhine and its estuaries, nematode density varied from 5.000 to 1.7 million per square metre, and about 50 genera were identified. Anoxic conditions appear to have less influence on the nematode abundance than the presence of ammonia. Based on nematode genera, an ecological typology of aquatic soils would appear to be feasible. The use of nematodes in environmental studies is discussed.