Geoderma
We compared the performances of kriging and two methods of interpolation which allow to account for an auxiliary variable: co-kriging, and kriging combined with regression. These two methods were applied to improve the interpolation of the soft layers depth (D s l ) measured by augering, using the bulk soil electrical conductivity (EC a ) measured by an electromagnetic instrument...
Generalizations about the morphology and genesis of acid sulphate soils at a regional scale are derived from a review of extensive though patchy soil survey data.A general sequence of sedimentation, accumulation of sulphides and burial of sulphitic material by peat or alluvium of low sulphide content, and a parallel sequence of soil profile development are illustrated by examples of unripe sulphitic...
The study concerns chemical and mineralogical properties of calcic horizons in relation to their physical environment such as position in the soil profile and the terrain. The carbonates were calcitic in upslope positions but dolomite was abundant in valley sites. The content of fluorine increased downslope. The distribution of the composition in the terrain indicates a sequential precipitation...
There is ample evidence that coarse-textured soils can be highly sensitive to crust formation under rainfall. One of the most controversial aspects of crust formation on such soils is the frequent occurrence of a thin clay band buried below a washed-out layer.In order to better understand the mechanisms that may lead to this vertical sorting in structural crusts, mixtures of 92.5% sand and 7.5% clay...
Erosion is the main cause of soil degradation in tropical regions, where the lack of methods for long-term studies is the principal constraint to addressing soil erosion problems. Recently, the analysis of 1 3 7 Cs redistribution within the landscape has been used for assessing long-term soil erosion and net deposition. In the present study, measurements of 1 3 7 ...
Three distinct soils which are developing on volcanic effusive rocks of Mt. Fogliano, San Martino and Mt. Cimino, and form part of the Cimini volcanic complex, north of Rome, were analysed and their physico-chemical, mineralogical and micromorphological characteristics are reported. These soils are believed to have developed in a fairly recent time, beginning around 20,000 years ago, under similar...
Studying the water transport in the soil-plant system requires information on the spatio-temporal variability of both subsystems and the ability to assess the impact of the soil heterogeneity and of the biological responses on the coupling between vegetation and its substrate. This study was conducted for 2 years in a vineyard in the Aude Valley, France, by measuring the particle size distribution...
Cadmium and Ni solubility in soils is of concern due to their biological toxicity, especially to humans. Free Cd 2 + and Ni 2 + activities in both contaminated and uncontaminated soils were determined using the chelation method. The measured Cd 2 + and Ni 2 + activities were highly pH dependent with correlation coefficients of 0.99 and 0.80 in the...
The relative areas of soil profile classes are found to show an unexpected regularity in various landscapes (where relative area is defined as the proportion of the total soil-covered area of a region which is occupied by a particular soil class). If i classes are ordered by their relative areas (A 1 , A 2 A i ) then a plot of the cumulative relative areaCA n (the...
The Quaternary environmental history of the northern Great Basin is characterized by a combination of lower temperature and higher moisture than present. Using water-balance analysis of soils sampled along a climatic gradient, we demonstrate that long-term average effective moisture was about 2-4 cm yr - 1 greater than present. Although this long-term average represents most of Quaternary...
The spatial variation of organic matter and of related pedological properties was studied in surface soils near two species of caulescent paramo rosettes in the Andes of Venezuela. Organic matter showed a distinctive pattern of concentration within small oval-shaped areas which extended both downslope and downwind from tall Coespeletia timotensis plants. The influence of wind on organic-matter distribution...
Soil clays differing widely in mineralogy were individually mixed with sand and silt fractions from an Alfisol. The mixtures dominated by Ca 2 + were wet and dried ten times to simulate field conditions and promote microaggregation of the soils. Compacted cores were prepared at fixed water contents and tensile strengths of the cores were measured before and after a number of wetting...
Information on the most important physical properties that influence the saturated hydraulic conductivity (K s ) of soils is useful in modelling water and solute movement during ponded infiltration and in estimating both temporal and spatial variation in K s . In this study the K s of 18 sites with different land use histories on a watershed in the Nsukka plains of southeastern...
Field-scale variation in soil fertility can be a major source of uneven crop growth on acid soils of the humid tropics, but this has not received much research attention. We used factorial kriging (FKA) to analyze processes causing spatial variation in soil chemical properties (pH, P, K, Na, Ca, Mg, Al) measured at two depths within a single field on an acid Ultisol in the Philippines. A linear...
Relationships among the mineralogy, morphology and the formation processes of salt accumulations were studied in three sampling areas in the Flumen--Monegros district, which represent three geochemical environments [Na-SO 4 -Cl, Na-(Mg)-So 4 -Cl and Na-CO 3 -SO 4 -Cl], according to chemical and mineralogical results.The samples included both natural ones and others...
The top soil of a 14.5 km 2 region at la Chaux-de-Fonds in the Swiss Jura is exceptionally rich in cadmium. It contains an average of 1.3 mg per kg of soil. The spatial distribution of the metal has no simple pattern that could be explained by atmospheric deposition or agricultural practices.Thin soil contained most of its Cd at the surface; in thicker soil Cd is mainly concentrated between...
Useful interpretation of the mixed redox electrode potentials measured in soils and natural waters in partial equilibrium with atmospheric O 2 , is nearly impossible because most oxidized species of critically important N, S, Mn, Fe, and C are not electroactive. We propose that simple chemical tests be used in the field to group soils into the following soil redox status categories: Superoxic,...
Relatively little is known about the fixed NH 4 -N status of soils in the semi-arid tropics (SAT) but information is needed in view of its role in N cycling and the N economy of the soils. The distribution of fixed NH 4 -N and C ratios of soil profiles from two benchmark Vertisols and one Alfisol in the Indian SAT were studied.From 15.9 to 58.6% of the total soil N was present as...