Geoderma
In the Tamoa Valley, on the western coast of New Caledonia, a Vertisol sequence shows a downslope transition from calcimagnesic Vertisols containing gypsum, aragonite, and magnesium-calcite, derived from flysch colluvium, to hypermagnesic Vertisols, rich in dolomite and magnesite, and derived from peridotite and serpentinite alluvium deposited by the Tamoa River.Gypsum, magnesium-calcite and magnesite...
We evaluate data from a chronosequence study of landslide scars, ranging in age from 1-55+ yr, in the Luquillo Experimental Forest (LEF) a subtropical lower montane wet forest (sensu Holdridge) in eastern Puerto Rico. Surface mineral soil (0-10 cm) base saturation index (BSI) values increase during primary succession in the LEF (R=0.85, P<0.001). Both BSI values and major nutrient cation concentrations...
P-sorption isotherms were determined for calcium carbonate (AR grade) and four soils, which contain various amounts of iron oxides and calcium carbonate. The results could be put into the Langmuir equation. The sorption maximum of calcite was 26 mg P kg - 1 . This result was used to calculate the surface coverage of calcite by sorbed P. The model indicated that only 14 to 18 of the...
In this study, the depth distribution of organic carbon (OC) content in a sandy soil was characterized for a small agricultural plot (1.5 ha). The means and the distributions for measured OC were used as sorption-related parameters in a solute transport model to predict the movement of the herbicide atrazine in the unsaturated zone. Simulations were performed in order to assess the impact of OC...
Mapping rules based on the knowledge of regional soil patterns -- soil pattern rules -- can be acquired from a previous soil survey of a small but representative sample area called the reference area. They can then be used in new soil surveys carried out on wider areas; this allows both to select the observation points and to predict which soil unit occurs at non-observed points. A quantified formulation...
The physical and chemical development of three Holocene-aged Spodosols, found in the northeastern United States on differing parent materials, was analyzed using mass-balance modeling in conjunction with complementary micromorphological and chemical techniques. The accumulation of soil organic matter, in combination with the process of past root growth, resulted in profile volumetric expansions of...
Palygorskite- or sepiolite-containing soils occur at elevations up to 1000 m, in gently sloping landscapes formed by aeolian sands or by strongly eroded pedisediments overlying the Namaqualand Metamorphic Complex. The unconsolidated sands are in various stages of calcretization. Most of the soils are sandy, shallow, non-saline, with a pH ranging between 7.2 and 8.2. Carbonate contents are low,...
Concentration-adsorption-moisture equations (CAM equations) were developed that enabled adsorbed boron and the boron concentration at any soil moisture content to be calculated from the measured boron concentration and moisture content of a saturated water extract, the bulk density and the measured coefficients defining the Langmuir and Freundlich boron adsorption isotherms. The CAM equations were...
Scanning electron microscopy was used to assess the weathering status of plagioclase and alkali feldspar grains isolated from sandy outwash soils located under three vegetation communities: mixed red and white pine, maple-basswood, and white cedar. Feldspars were selected for this study because they were the most common weatherable minerals in these sandy soils. A morphological weathering index,...
The distribution of native zinc in 18 soils of China and the redistribution and transformations of added soluble zinc in 3 representive soils (acid, neutral and calcareous) were studied. Native Zn in 18 soils of China was mainly distributed over the residual fraction (60-99%) and the crystalline iron oxide fraction (5-30%). The percentages of the residual and exchangeable fractions were higher and...
At three relatively unpolluted sites in beech (Fagus sylvatica) woodlands on the Chiltern Hills of southern England, measurements were made over one year of the amount and composition of precipitation, throughfall, stemflow, and drainage below the soil organic layer. At two sites the soils were acidic and at the third the soil contained calcium carbonate. Comparison was made between the soil acidification...
Hedgerows of Cassia siamea were planted 4 m apart in a maize/cowpea rotation on a 14% slope of a Lixisol/Alfisol in 1988 at Machakos, Kenya. Infiltration rates were measured in situ across hedgerow barriers with a drip infiltrometer. During the dry season the steady infiltration rate under the hedgerows was 135 mm h - 1 while on the alleys in between it was 41-49 mm h - 1 ...
Vertical distribution of Zn, Pb, Cu and Cd was studied in podzol soil profiles of adjacent forested and clear-cut areas in a region contaminated with Zn, Pb and Cd from long-range atmospheric transport. This was in order to investigate possible effects of deforestation on accumulation and distribution patterns of these metals in surface soil profiles. Lower Zn and Cd contents were observed in the...
Mineralogy of clay sized particles and rainstorm characteristics are among the major factors that determine the nature of soil sealing. This research was designed to further our knowledge about the role of clay mineralogy and rainstorm characteristics on crust formation. Four loess soils from different geographic locations (Canada, USA, China, and Belgium) were used in this study. Preliminary studies...
Humic acids (HAs) have been isolated according to conventional extraction, fractionation and purification methods from soil samples collected in a hop field in Bavaria (Germany), under the plant rows (HAa), between the rows (HAb) and in an adjacent unexploited soil location (control, HAc). Interaction products between each HA sample and each of the herbicides atrazine, simazine, diquat and paraquat...
The ant Lasius neoniger Emery is one of the most abundant ant species found in the temperate regions of North America and has been studied primarily from an entomological standpoint. This study was conducted to characterize its nest structure and implications to soil modification. To study the structure, development, and micromorphological characteristics of the ant nests, we constructed three-dimensional...
The nature of the short-range ordered Al and Fe minerals of the spodic B horizons of northern Scandinavia was studied by selective dissolution, transmission electron microscopy, infrared absorption and sulphate adsorption experiments. Imogolite-type materials (proto-imogolite allophane and well-developed imogolite) were the predominant oxalate-extractable Al minerals. Minor amounts of gibbsite and...
Jarosite-type minerals, MFe 3 (SO 4 ) 2 (OH) 6 (M = K, jarosite; M = Na, natrojarosite), were studied in two Sulfic Cryaquepts developed in sulfidic sediments deposited in the Baltic between 7000 and 4000 BP. The jarosites were characterized by X-ray diffraction (XRD) and a selective dissolution technique. Selective dissolution showed that the K molar ratio in the...
Quartz and mica contents of soils developed on volcanic materials in the Canary Archipelago (Lanzarote, Tenerife, Gomera and La Palma islands), off western Africa are often higher in surficial horizons with higher rainfall and older landscape age. The soil quartz particles are fine-grained (less than 53 μm in diameter) and well-sorted. The oxygen isotopic abundance (δ 1 8 O S ...