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Volcanic heavy minerals are found in the A and B horizons of soils on moraines of the western Wind River Mountains of Wyoming. Volcanic minerals do not occur in the underlying moraine sediments derived from plutonic and metamorphic bedrock. Sources of the volcanics are the sedimentary rocks of the Green River Basin. The presence of volcanic minerals in the Green River Basin and their patterns of distribution in the moraine soils indicate eolian sedimentation is an important factor of soil genesis in this region. Moraines affected by eolian sediments include the Pinedale and Temple Lake/Indian Basin type localities. The presence of eolian sediments in both Pinedale and Holocene deposits suggests eolian addition is...
Categories: Publication; Types: Citation, Journal Citation; Tags: Geoderma
The large land area occupied by arid lands, roughly 36% to 40% globally, underscores the importance for understanding how these ecosystems function in the global carbon cycle. Few studies have directly examined soil organic carbon (SOC) dynamics and the effect of vegetation on SOC and microbial community structure in arid ecosystems. The objective of this study was to determine the effect of vegetation type on SOC dynamics in an arid, hyperthermic Sonoran Desert ecosystem. We specifically examined the influence of Prosopis velutina (mesquite), Larrea tridentata (creosote), and a combination of Bouteloua barbata, Bouteloua aristidoides, Aristida adscensionis, and Cynodon dactylon (mixed grass) vegetation types on...
Soil is defined here in terms of arbitrary boundaries rather than of functions of a soil body. Soil animals are defined in relation to their effects on the soil body. Animals living in the soil body and intimately related to it are indeed part of the soil. Animals living above the soil make contributions to it. Many animals are amphihabitant, that is, they live for a time in the soil and then in environments outside the soil. Exopedonic (outside the soil) and endopedonic (inside the soil) animals are considered with respect to twelve activities: mounding, mixing, forming voids, back-filling voids, forming and destroying peds, regulating soil erosion, regulating movement of water and air in soil, regulating plant...
Categories: Publication; Types: Citation, Journal Citation; Tags: Geoderma
Phosphorus (P) availability has generally been assumed to be the limiting or co-limiting factor for plant growth in alpine environments. To test this assumption, the biogeochemistry of phosphorus (P) along an alpine topographic/snow gradient located on Niwot Ridge, Colorado Front Range was studied in the context of P limitation for plant growth. We measured the various P pools using a selective extraction procedure, determined sorption parameters, and quantified P availability indices. The topographic/snow gradient at Niwot Ridge is divided by the aspect and slope position in relation to the dominant westerly winds into leeward-sloping, windward-sloping and generally level sites. Our study found that the snow-melting...
A recently proposed meaning of pedoderm is more formally defined so as to contrast it with an older definition that is used infrequently in soil stratigraphy. It is defined here as the thin layer of soil at the interface with the atmosphere, a few millimetres to centimetres thick, within which certain properties may exhibit a marked vertical change in expression sometimes not readily detected through field observation. The function of this generic term is primarily to draw attention to the variation of soil surface characteristics on a micro-scale that might otherwise be overlooked. It has implications for understanding material fluxes and ecosystem function and the use of remote sensing for soil evaluation. Published...
This paper reviews simplified process models for denitrification. More than fifty models were considered. The majority of these (simple) models are based on potential denitrification—either measured as a soil's property or computed from organic C dynamics—or consider denitrification as a first-order decay process. As it is generally accepted that environmental soil conditions affect the denitrification process, reduction functions are used. Although denitrification is truly driven by the non-availability of oxygen, most authors argue that oxygen dynamics in soil is hard to simulate (or to measure). Therefore, water content is used as a complementary for oxygen diffusion. The higher the water content, the less...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
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Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5–40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
The renaissance was an intellectually-rich period following a period of stasis in the medieval period. Something analogous appears to be currently taking place in soil science where novel approaches to thought are combined with a revival of ideas from the past. Renewed interest in agriculture (food, feed, fuel) and numerous publications have brought soils back onto the global research agenda. The need for up-to-date and fine resolution soil information and the revival of soil research has been highlighted and prioritised in several recent studies by the UN and other international organizations. Soil erosion, nutrient depletion and pollution are key issues that have been brought up in many recent reports – in most...
Salinization and alkalinization are the most common land degradation processes, particularly occurring in arid and semi-arid regions, where precipitation is too low to maintain a regular percolation of rainwater through the soil. Under such a climatic condition, soluble salts are accumulated in the soil, influencing soil properties and environment which cause lessening of the soil productivity. The consistent identification of the processes is essential for sustainable soil management. Identification, large scale mapping and monitoring of the salt-affected areas have been done using three different data and techniques. Remote sensing has been widely used to detect and map salt-affected areas, since thousands of...
Limited information exists of the differences in soil physical and hydrologic properties in invasive Bromus tectorum L. (BT) (cheatgrass) habitats versus native Artemisia tridentata Nutt. (AT) (big sagebrush) habitats. Our objective was to assess differences in soil physical and hydrological properties by comparing measures of soil particle size; aggregate stability; hydrophobicity; bulk density; penetration resistance; surface roughness; and infiltration (double-ring and mini-disk tension infiltrometer) between habitats. BT sites were sampled following AT stand replacing fires that resulted in near continuous BT establishment. Sites characterized by AT, and not burned, were sampled as controls. Significantly lower...
The soils across treeline should vary because of direct effects of biological differences of coniferous subalpine forest and the herbaceous alpine tundra in Colorado. In addition, the change in life form may indirectly affect soils because of interactions of the vegetation and wind-driven deposition processes. This is particularly important as nitrogen (N) saturation is a growing concern in high elevation ecosystems, and treeline is predicted to be a deposition hotspot. The vegetation transition at treeline provides an opportunity to test the effects of vegetation, topography, and external inputs on soils at three spatial scales. First, a regional evaluation of soils at eleven abrupt treeline sites was made comparing...
    map background search result map search result map Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients Atmospheric dust in modern soil on aeolian sandstone, Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients