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Soil Properties (soil + property)
Selected AbstractsEFFECTS OF TOPOGRAPHY AND SOIL PROPERTIES ON RECHARGE AT TWO SITES IN AN AGRICULTURAL FIELD,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2000Geoffrey N. Delin ABSTRACT: Field experiments were conducted from 1992 to 1995 to estimate ground water recharge rates at two sites located within a 2.7-hectare agricultural field. The field lies in a sand plain setting in central Minnesota and is cropped continuously in field corn. The sites are located at a topographically high (upland) site and a topographically low (lowland) site in an effort to quantify the effects of depression focusing of recharge. Three site-specific methods were used to estimate recharge rates: well hydrograph analysis, chlorofluorocarbon age dating, and an unsaturated zone water balance. All three recharge methods indicated that recharge rates at the lowland site (annual average of all methods of 29 cm) exceeded those at the upland site (annual average of 18 cm). On an annual basis, estimates by the individual methods ranged from 12 to 44 percent of precipitation at the upland site and from 21 to 83 percent at the lowland site. The difference in recharge rates between the sites is primarily attributed to depression focusing of surface water runon at the lowland site. However, two other factors were also important: the presence of thin lamellae at the upland site, and coarser textured soils below a depth of 1.5 m at the lowland site. [source] Evaluating the contribution of soil properties to modifying lead phytoavailability and phytotoxicity,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Elizabeth A. Dayton Abstract Soil properties affect Pb bioavailability to human and ecological receptors and should be considered during ecological risk assessment of contaminated soil. We used path analysis (PA) to determine the relative contribution of soil properties (pH, organic C [OC], amorphous Fe and Al oxides [FEAL], and cation-exchange capacity [CEC]) in modifying Pb bioavailability. The response of biological endpoints (bioaccumulation and dry matter growth [DMG]) of lettuce (Lactuca sativa) grown on 21 Pb-spiked (2,000 mg/kg) soils were determined. Lettuce tissue Pb ranged from 3.22 to 233 mg/kg, and relative DMG ranged from 2.5 to 88.5% of their respective controls. Simple correlation showed strong relationships between CEC and OC (p < 0.01) and weaker relationships between pH and FEAL (p < 0.05) and Pb bioaccumulation. Results of PA suggest that soil pH increased the negative surface charge of organic matter and clay, thereby increasing CEC and decreasing Pb bioaccumulation. Also, the direct effect of OC on tissue Pb can be attributed to formation of surface Pb complexes by organic matter functional group ligands. Increased OC and/or CEC reduced Pb solubility and bioavailability in the 21 soils in the present study. The relative importance of soil properties likely will vary between studies employing different soils. Soil properties should be considered during the ecological risk assessment of metal in contaminated soils. Path analysis is useful for ecological studies involving soils with a wide range of physicochemical properties and can assist in site risk assessment of metals and remediation decisions on contaminated sites. [source] Impact of animal waste lagoon effluents on chlorpyrifos degradation in soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2000Xinjiang Huang Abstract Animal-derived lagoon effluents are a good source of inorganic nutrients and organic matter; however, they may impact the degradation and transport of soil-applied pesticides. The degradation of chlorpyrifos in poultry-, swine-, and cow-derived effluents and effluent-soil matrices were studied using batch and column incubation studies. Chlorpyrifos was degraded by aerobic microbial processes in animal-derived lagoon effluents. Microbial community analysis by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal ribonucleic acid genes showed that a single band became dominant in effluent during chlorpyrifos degradation. In soils, both biotic and abiotic degradation contributed significantly to the overall dissipation of chlorpyrifos. Large differences in degradation rates were observed between soils, with the fastest rate observed in soil with higher pH and cation-exchange capacity. Effluents appeared to have only a minor effect on chlorpyrifos degradation in soils, although effluent-induced increases in soil-solution pH over time may enhance hydrolysis by a few percent in low-pH soils. Soil properties, not effluent properties, appear to control chlorpyrifos degradation under laboratory conditions; however, the impact on changes in soil properties and microbial ecology with long-term effluent irrigation warrants further investigation. [source] The GEOTOP snow moduleHYDROLOGICAL PROCESSES, Issue 18 2004Fabrizio Zanotti Abstract A snow accumulation and melt module implemented in the GEOTOP model is presented and tested. GEOTOP, a distributed model of the hydrological cycle, based on digital elevation models (DEMs), calculates the discharge at the basin outlet and estimates the local and distributed values of several hydro-meteorological quantities. It solves the energy and the mass balance jointly and deals accurately with the effects of topography on the interactions among radiation physics, energy balance and the hydrological cycle. Soil properties are considered to depend on soil temperature and moisture, and the heat and water transfer in the soil is modelled using a multilayer approach. The snow module solves for the soil,snow energy and mass exchanges, and, together with a runoff production module, is embedded in a more general energy balance model that provides all the boundary conditions required. The snowpack is schematized as a single snow layer where a limited number of physical processes are described. The module can be seen essentially as a parameter-free model. The application to an alpine catchment (Rio Valbiolo, Trentino, Italy), monitored by an in situ snow-depth sensor, is discussed and shown to give results comparable to those of more complex models. Copyright © 2004 John Wiley & Sons, Ltd. [source] Linkages of plant traits to soil properties and the functioning of temperate grasslandJOURNAL OF ECOLOGY, Issue 5 2010Kate H. Orwin Summary 1.,Global change is likely to alter plant community structure, with consequences for the structure and functioning of the below-ground community and potential feedbacks to climate change. Understanding the mechanisms behind these plant,soil interactions and feedbacks to the Earth-system is therefore crucial. One approach to understanding such mechanisms is to use plant traits as predictors of functioning. 2.,We used a field-based monoculture experiment involving nine grassland species that had been growing on the same base soil for 7 years to test whether leaf, litter and root traits associated with different plant growth strategies can be linked to an extensive range of soil properties relevant to carbon, nitrogen and phosphorus cycling. Soil properties included the biomass and structure of the soil microbial community, soil nutrients, soil microclimate and soil process rates. 3.,Plant species with a high relative growth rate (RGR) were associated with high leaf and litter quality (e.g. low toughness, high nitrogen concentrations), an elevated biomass of bacteria relative to fungi in soil, high rates of soil nitrogen mineralization and concentrations of extractable inorganic nitrogen, and to some extent higher available phosphorus pools. 4.,In contrast to current theory, species with a high RGR and litter quality were associated with soils with a lower rate of soil respiration and slow decomposition rates. This indicates that predicting processes that influence carbon cycling from plant traits may be more complex than predicting processes that influence nitrogen and phosphorus cycling. 5.,Root traits did not show strong relationships to RGR, leaf or litter traits, but were strongly correlated with several soil properties, particularly the biomass of bacteria relative to fungi in soil and measures relating to soil carbon cycling. 6.,Synthesis. Our results indicate that plant species from a single habitat can result in significant divergence in soil properties and functioning when grown in monoculture, and that many of these changes are strongly and predictably linked to variation in plant traits associated with different growth strategies. Traits therefore have the potential to be a powerful tool for understanding the mechanisms behind plant,soil interactions and ecosystem functioning, and for predicting how changes in plant species composition associated with global change will feedback to the Earth-system. [source] Soil properties and tree growth along an altitudinal transect in Ecuadorian tropical montane forestJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2008Wolfgang Wilcke Abstract In tropical montane forests, soil properties change with increasing altitude, and tree-growth decreases. In a tropical montane forest in Ecuador, we determined soil and tree properties along an altitudinal transect between 1960 and 2450 m asl. In different vegetation units, all horizons of three replicate profiles at each of eight sites were sampled and height, basal area, and diameter growth of trees were recorded. We determined pH and total concentrations of Al, C, Ca, K, Mg, Mn, N, Na, P, S, Zn, polyphenols, and lignin in all soil horizons and in the mineral soil additionally the effective cation-exchange capacity (CEC). The soils were Cambisols, Planosols, and Histosols. The concentrations of Mg, Mn, N, P, and S in the O horizons and of Al, C, and all nutrients except Ca in the A horizons correlated significantly negatively with altitude. The C : N, C : P, and C : S ratios increased, and the lignin concentrations decreased in O and A horizons with increasing altitude. Forest stature, tree basal area, and tree growth decreased with altitude. An ANOVA analysis indicated that macronutrients (e.g., N, P, Ca) and micronutrients (e.g., Mn) in the O layer and in the soil mineral A horizon were correlated with tree growth. Furthermore, lignin concentrations in the O layer and the C : N ratio in soil affected tree growth. These effects were consistent, even if the effect of altitude was accounted for in a hierarchical statistical model. This suggests a contribution of nutrient deficiencies to reduced tree growth possibly caused by reduced organic-matter turnover at higher altitudes. [source] Soil properties, but not plant nutrients (N, P, K) interact with chemically induced resistance against powdery mildew in barleyJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2003Joachim Wiese Abstract Chemically induced resistance is a promising method of plant protection against diseases, which can be triggered by systemically acting chemical inducers such as BTH (benzo(1, 2, 3)thiadiazole-carbothioic-acid-S-methylester). BTH is commercially distributed as a 50,% formulation, called Bion®. The uncertain success of Bion® application in controlling infection by powdery mildew is a major obstacle in using induced resistance for plant protection in agriculture. This study aimed to investigate the effect of soil properties, selected macronutrients (N, P, and K), and addition of organic matter on induced resistance and to identify possible factors responsible for the high variability of BTH effect under field conditions. A pot experiment under open-air conditions was set up using the pathosystem Hordeum vulgare cv. Ingrid / Blumeria graminis f. sp. hordei race A6. The different soils strongly affected the resistance of barley plants against powdery mildew after BTH treatment. The infection of barley by powdery mildew was lower than on all other soils when grown on an acid forest soil which was limed up to pH 4.9, even after BTH treatment. A reproducible induction of pathogen resistance by BTH was shown only on a mineral soil (Kleinlinden) with a negligible C content. Application of N, P, and K did not consistently affect the induction of resistance by BTH. The addition of green manure and compost led to an enhanced variability of resistance induction on the soil "Kleinlinden". Possible effects of soil microflora on resistance induction are discussed. Bodeneigenschaften, aber nicht Pflanzennährstoffe (N, P, K) interagieren mit der chemisch induzierten Resistenz gegen Gerstenmehltau in Gerste Chemisch induzierte Resistenz ist eine viel versprechende Methode im Pflanzenschutz, welche durch systemisch wirkende Substanzen wie BTH (Benzo(1, 2, 3)-thiadiazolcarbothion-Säure- S -Methylester) induziert werden kann. BTH ist die wirksame Komponente des kommerziell erhältlichen Produkts Bion®. Allerdings ist die Wirksicherheit von Bion® im Feld gering, wodurch die Anwendung des Produkts im Pflanzenschutz eingeschränkt ist. Das Ziel der vorliegenden Arbeit war es, den Einfluss verschiedener Böden, ausgewählter Makronährstoffe (N, P und K) und des Zusatzes von organischem Material zum Boden auf die induzierte Resistenz zu untersuchen und Faktoren zu identifizieren, die für die unsichere BTH-Wirkung im Feld verantwortlich sind. Dafür wurden Gefäßexperimente unter freilandähnlichen Bedingungen durchgeführt. In diesen wurde das Pathosystem Hordeum vulgare cv. Ingrid / Blumeria graminis f. sp. hordei Stamm A6 verwendet. Es wurde ein starker Einfluss des Bodens auf die Resistenz der Gerste gegen Gerstenmehltau nach BTH-Behandlung ermittelt. Die Mehltauinfektion von Gerste, welche auf einem sauren Waldboden kultiviert wurde, der auf einen pH-Wert von 4, 9 aufgekalkt worden war, war niedriger als auf allen anderen Böden, selbst nach BTH-Behandlung. Eine reproduzierbare Induktion der Pathogenresistenz durch BTH konnte nur auf einem Mineralboden mit vernachlässigbarem C-Gehalt gezeigt werden. Die Ernährung mit N, P und K hatte keinen konsistenten Einfluss auf die Resistenzinduktion mittels BTH. Der Zusatz von Kompost und Gründünger zum Boden ,Kleinlinden" erhöhte die Variabilität der Resistenzinduktion. Der mögliche Einfluss der Bodenmikroflora auf die Resistenzinduktion wird diskutiert. [source] Effects of field reorganisation on the spatial variability of runoff and erosion rates in vineyards of Northeastern SpainLAND DEGRADATION AND DEVELOPMENT, Issue 1 2010M. C. Ramos Abstract This study analyses the spatial variability of runoff and erosion rates in vineyards due to mechanisation works. Runoff samples were collected at three positions in two plots after 33 erosive events in three years (2001, 2003, 2004) with different rainfall patterns. Three replications were considered at each position. Soil properties were evaluated in order to analyse its relationship with runoff and erosion rates. Runoff and erosion rates were, on average, higher in the levelled plot (HD), ranging between 8·4 and 34·3 per cent, than in the non-levelled plot (LD) ranging between 8·2 and 24·1 per cent. Mean sediment concentration in runoff ranged between 6 and 8,g,L,1 in the HD plot and about 4·6,g,L,1 in the LD plot, but with high differences within the plot. In the HD plot, runoff-rainfall rates were significantly higher (at 95 per cent level) in the upper part of the slope and decreased along the slope, while in the LD plot, differences in runoff rates were not significant and similar to those observed in the less disturbed areas of the HD plot. The higher susceptibility to soil sealing in areas where the original topsoil was removed conditioned runoff rates. In the lower part of the HD plot runoff rates were, on average, 20 per cent lower than in the upper part of the slope. In those positions runoff rates up to 79 per cent were recorded. Organic matter content and water retention capacity at different potentials are the soil characteristics related to the differences on runoff and erosion rates in the resulting soils. Copyright © 2009 John Wiley & Sons, Ltd. [source] Soil properties and perceived disturbance of grasslands subjected to mechanized military training: evaluation of an indexLAND DEGRADATION AND DEVELOPMENT, Issue 3 2007D. P. Althoff Abstract Mechanized maneuver training impacts the landscape by creating depressions, compacting soils, producing bare ground areas, transporting seeds of invasive plants, and crushing vegetation. We measured 3 physical, 13 chemical, and 2 biological soil properties and used a disturbance index (DI) based on perceptions of soil conditions on a military installation to assess the condition of 100,×,100,m plots (1 ha): 10 in 2002 and 10 in 2004. Potential DI scores range from 0 (no appreciable evidence of disturbance) to 1 (>95 per cent of the plot disturbed). Bulk density, porosity (%), and water content (%),all at 5·1,10·0,cm depth, and nematode family richness (NFR) were significantly, negatively correlated (Spearman coefficients, rs) with the DI of both years. The strong negative correlation (rs,=,,0·69 in 2002, ,0·79 in 2004) of NFR with the DI appears to reflect the status of nematode diversity and, therefore, may serve as a useful, inexpensive approach to rapidly assessing grasslands subjected to mechanized military training. Copyright © 2007 John Wiley & Sons, Ltd. [source] Salvage Logging, Ecosystem Processes, and Biodiversity ConservationCONSERVATION BIOLOGY, Issue 4 2006D.B. LINDENMAYER conservación de la biodiversidad; gestión forestal; procesos ecosistémicos Abstract:,We summarize the documented and potential impacts of salvage logging,a form of logging that removes trees and other biological material from sites after natural disturbance. Such operations may reduce or eliminate biological legacies, modify rare postdisturbance habitats, influence populations, alter community composition, impair natural vegetation recovery, facilitate the colonization of invasive species, alter soil properties and nutrient levels, increase erosion, modify hydrological regimes and aquatic ecosystems, and alter patterns of landscape heterogeneity. These impacts can be assigned to three broad and interrelated effects: (1) altered stand structural complexity; (2) altered ecosystem processes and functions; and (3) altered populations of species and community composition. Some impacts may be different from or additional to the effects of traditional logging that is not preceded by a large natural disturbance because the conditions before, during, and after salvage logging may differ from those that characterize traditional timber harvesting. The potential impacts of salvage logging often have been overlooked, partly because the processes of ecosystem recovery after natural disturbance are still poorly understood and partly because potential cumulative effects of natural and human disturbance have not been well documented. Ecologically informed policies regarding salvage logging are needed prior to major natural disturbances so that when they occur ad hoc and crisis-mode decision making can be avoided. These policies should lead to salvage-exemption zones and limits on the amounts of disturbance-derived biological legacies (e.g., burned trees, logs) that are removed where salvage logging takes place. Finally, we believe new terminology is needed. The word salvage implies that something is being saved or recovered, whereas from an ecological perspective this is rarely the case. Resumen:,Resumimos los impactos documentados y potenciales de la cosecha de salvamento , una forma de cosecha de madera que remueve árboles y otros materiales biológicos después de una perturbación natural. Tales operaciones pueden reducir o eliminar legados biológicos, modificar hábitats post perturbación, influir en poblaciones, alterar la composición de comunidades, impedir la recuperación de la vegetación natural, facilitar la colonización de especies invasoras, alterar las propiedades del suelo y de niveles de nutrientes, incrementar la erosión, modificar regímenes hidrológicos y ecosistemas acuáticos, y alterar patrones de heterogeneidad del paisaje. Estos impactos se pueden asignar a tres efectos amplios e interrelacionados: (1) alteración de la complejidad estructural del bosque; (2) alteración de procesos y funciones ecológicas; y (3) alteración de poblaciones de especies y de la composición de la comunidad. Algunos impactos pueden ser diferentes a o adicionales a los efectos de la cosecha de madera tradicional que no es precedida de una perturbación natural severa porque las condiciones antes, durante y después de la cosecha de salvamento pueden diferir de las que caracterizan a la cosecha de madera tradicional. Los impactos potenciales de la cosecha de salvamento a menudo han sido pasados por alto, en parte porque los procesos de recuperación del ecosistema después de una perturbación natural son poco conocidos y en parte porque los efectos acumulativos potenciales de perturbaciones naturales y humanas no han sido bien documentados. Se requieren políticas ecológicamente informadas para la cosecha de salvamento para que cuando ocurran las perturbaciones naturales se evite la toma de decisiones en situaciones de crisis. Estas políticas deberán establecer zonas exentas de salvamento y límites a las cantidades de legados biológicos derivados de la perturbación (e. g., árboles quemados, troncos) que son removidos donde se lleva a cabo la cosecha de salvamento. Finalmente, creemos que se requiere una nueva terminología. La palabra salvamento implica que algo esta siendo salvado o recuperado, y este raramente es el caso desde una perspectiva ecológica. [source] The role of vegetation patterns in structuring runoff and sediment fluxes in drylandsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2005Juan Puigdefábregas Abstract The dynamics of vegetation-driven spatial heterogeneity (VDSH) and its function in structuring runoff and sediment fluxes have received increased attention from both geomorphological and ecological perspectives, particularly in arid regions with sparse vegetation cover. This paper reviews the recent findings in this area obtained from field evidence and numerical simulation experiments, and outlines their implications for soil erosion assessment. VDSH is often observed at two scales, individual plant clumps and stands of clumps. At the patch scale, the local outcomes of vegetated patches on soil erodibility and hydraulic soil properties are well established. They involve greater water storage capacity as well as increased organic carbon and nutrient inputs. These effects operate together with an enhanced capacity for the interception of water and windborne resources, and an increased biological activity that accelerates breakdown of plant litter and nutrient turnover rates. This suite of relationships, which often involve positive feedback mechanisms, creates vegetated patches that are increasingly different from nearby bare ground areas. By this way a mosaic builds up with bare ground and vegetated patches coupled together, respectively, as sources and sinks of water, sediments and nutrients. At the stand scale within-storm temporal variability of rainfall intensity controls reinfiltration of overland flow and its decay with slope length. At moderate rainfall intensity, this factor interacts with the spatial structure of VDSH and the mechanism of overland flow generation. Reinfiltration is greater in small-grained VDSH and topsoil saturation excess overland flow. Available information shows that VDSH structures of sources and sinks of water and sediments evolve dynamically with hillslope fluxes and tune their spatial configurations to them. Rainfall simulation experiments in large plots show that coarsening VDSH leads to significantly greater erosion rates even under heavy rainfall intensity because of the flow concentration and its velocity increase. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mineral soil surface crusts and wind and water erosionEARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2004Michael J. Singer Abstract The ,rst few millimetres of soil largely control the soil's response to the eroding forces of wind and water. The tendency of soils to form surface seals and crusts in,uences the processes of wind and water erosion differently. For wind, dry particle size distribution and particle organization determine the shear strength and threshold wind velocity necessary to initiate particle movement. In loams and clay loams, seals and crusts decrease roughness but increase surface soil strength, generally decreasing wind erosion. Conversely, in sand and sandy loams, loose erodible sandy material may either deposit on the crust and is subject to erosion or it may disrupt the crust, accelerating the erosion process. For water erosion, particle size distribution and structure determine in,ltration rate, time to ponding, and energy required for soil particle detachment. Seals and crusts tend to decrease in,ltration rate and time to ponding thus increasing overland ,ow and soil erosion. This paper brie,y reviews how permanent and time-dependent soil properties in,uence surface seals and crusts and how these affect soil erosion by wind and water. The tendency of a soil to form a seal and crust depends to some degree on the time-dependent property of soil structural stability, which tends to increase with increasing clay content and smectitic mineralogy which are permanent properties. These permanent properties and their effect on structure are variable depending on dynamic properties of exchangeable sodium percentage and soil solution electrical conductivity. Antecedent water content prior to irrigation or rainfall, rate of wetting before an erosive event and aging, the time between wetting and an erosive event, greatly in,uence the response of soil structure to raindrop impact. The effect of these dynamic processes is further in,uenced by the static and dynamic properties of the soil. Weak structure will be less in,uenced by wetting rate than will a soil with strong structure. Process-based models of wind and water erosion need to consider the details of the interactions between soil static and dynamic properties and the dynamic processes that occur prior to erosive events. Copyright © 2004 John Wiley & Sons, Ltd. [source] Measurement and data analysis methods for field-scale wind erosion studies and model validation,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2003Ted M. Zobeck Abstract Accurate and reliable methods of measuring windblown sediment are needed to con,rm, validate, and improve erosion models, assess the intensity of aeolian processes and related damage, determine the source of pollutants, and for other applications. This paper outlines important principles to consider in conducting ,eld-scale wind erosion studies and proposes strategies of ,eld data collection for use in model validation and development. Detailed discussions include consideration of ,eld characteristics, sediment sampling, and meteorological stations. The ,eld shape used in ,eld-scale wind erosion research is generally a matter of preference and in many studies may not have practical signi,cance. Maintaining a clear non-erodible boundary is necessary to accurately determine erosion fetch distance. A ,eld length of about 300 m may be needed in many situations to approach transport capacity for saltation ,ux in bare agricultural ,elds. Field surface conditions affect the wind pro,le and other processes such as sediment emission, transport, and deposition and soil erodibility. Knowledge of the temporal variation in surface conditions is necessary to understand aeolian processes. Temporal soil properties that impact aeolian processes include surface roughness, dry aggregate size distribution, dry aggregate stability, and crust characteristics. Use of a portable 2 tall anemometer tower should be considered to quantify variability of friction velocity and aerodynamic roughness caused by surface conditions in ,eld-scale studies. The types of samplers used for sampling aeolian sediment will vary depending upon the type of sediment to be measured. The Big Spring Number Eight (BSNE) and Modi,ed Wilson and Cooke (MWAC) samplers appear to be the most popular for ,eld studies of saltation. Suspension ,ux may be measured with commercially available instruments after modi,cations are made to ensure isokinetic conditions at high wind speeds. Meteorological measurements should include wind speed and direction, air temperature, solar radiation, relative humidity, rain amount, soil temperature and moisture. Careful consideration of the climatic, sediment, and soil surface characteristics observed in future ,eld-scale wind erosion studies will ensure maximum use of the data collected. Copyright © 2003 John Wiley & Sons, Ltd. [source] Methodology for preliminary seismic design of extended pile-shafts for bridge structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2006S. T. Song Abstract Seismic design of extended pile-shafts requires a careful consideration of the influence of the surrounding soil on the overall response of the soil,pile system. In this paper, a procedure that incorporates soil properties into the process is developed for preliminary seismic design of extended pile-shafts. The method follows the well-accepted approach of using a force reduction factor to determine the lateral strength of the structure. The procedure involves an iterative process to arrive at the required amount of longitudinal reinforcement. Other outcomes of the procedure include the appropriate lateral stiffness and strength, as well as an estimation of the local curvature demand and ultimate drift ratio that can be used to ensure a satisfactory lateral response. The design procedure is capable of providing reliable results for a practical range of structural and soil properties. The versatility of the procedure is illustrated using two numerical examples of extended pile-shafts constructed in different soil sites. Copyright © 2006 John Wiley & Sons, Ltd. [source] The effects of torsion and motion coupling in site response estimationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2003Mohammad R. Ghayamghamian Abstract Soil amplification characteristics are investigated using data from the Chibaken-Toho-Oki earthquake and its aftershocks recorded at Chiba dense array in Japan. The frequency-dependent amplification function of soil is calculated using uphole-to-downhole spectral ratio analysis, considering the horizontal components of shear wave. The identified spectral ratios consistently demonstrate the splitting of peaks in their resonance frequencies and low amplification values in comparison with a 1D model. The torsional behaviour and horizontal ground motion coupling are clarified as the reasons for these phenomena at the site. To prove the hypothesis, the torsional motion is directly evaluated using the data of the horizontal dense array in different depths at the site. The comparison between Fourier spectra of torsional motion and identified transfer functions reveals the peaks at the same frequencies. The wave equation including torsion and horizontal motion coupling is introduced and solved for the layered media by applying wave propagation theory. Using the developed model, the effects of torsional motion with horizontal motion coupling on soil transfer function are numerically examined. Splitting and low amplification at resonance frequencies are confirmed by the results of numerical analysis. Furthermore, the ground motion in two horizontal directions at the site is simulated using site geotechnical specification and optimizing the model parameters. The simulated and recorded motions demonstrate good agreement that is used to validate the hypothesis. In addition, the spectral density of torsional ground motions are compared with the calculated one and found to be well predicted by the model. Finally, the results are used to explain the overestimation of damping in back-calculation of dynamic soil properties using vertical array data in small strain level. Copyright © 2003 John Wiley & Sons, Ltd. [source] Spatial variability of soil and nutrient characteristics of semi-arid grasslands and shrublands, Jornada Basin, New MexicoECOHYDROLOGY, Issue 1 2008Eva Nora Mueller Abstract Heterogeneity of vegetation and soil properties is characteristic of semi-arid and arid environments. The potential underlying causes of the dynamics that create this spatial variability, with consequent impacts on landscape connectivity and thus ecological and ecohydrological processes, are not clearly understood. An investigation was carried out into the spatial variability of ponded infiltration rate, soil moisture, soil-aggregate stability, vegetation cover, random roughness and nutrient content in the soil (ammonium, nitrate and phosphorus) at grassland and shrubland sites for two spatial scales in the Jornada Basin, in the northern part of the Chihuahua desert. At the plant-interplant scale, statistically significant differences exist between vegetated and non-vegetated sites for soil moisture and infiltration rate within both shrublands and grasslands. The spatial distributions of all other parameters follow a more complex scheme at this scale. At the landscape scale, distinct differences exist for most parameters between the grasslands and the shrubland sites. Geostatistical analysis revealed that the autocorrelation lengths are not simply a function of average shrub sizes, but may be caused by a more complex pattern probably related to the spatial layout of rill and inter-rill areas and other localized transfers of soil resources through the redistribution of water and wind. These results demonstrate the importance of understanding spatial linkages of processes within the landscape in understanding dryland ecosystem dynamics. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Dry Limit of Microbial Life in the Atacama Desert Revealed by Calorimetric ApproachesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2008N. Barros Abstract The Atacama desert in Chile is one of the driest and most lifeless environments on Earth. It rains possibly once a decade. NASA examined these soils as a model for the Martian environment by comparing their degradation activity with Martian soil and looking for "the dry limit of life". The existence of heterotrophic bacteria in Atacama soil was demonstrated by DNA extraction and by the isolation of microorganisms. So far, however, no data have been available about the metabolic activities in these soils due to the limitations of the existing methodologies when applied to desert soils. Calorimetry was used to obtain information on the metabolic and thermal properties of eleven soil samples collected at different sites in the Atacama desert. Differential scanning calorimetry and isothermal calorimetry were employed to determine the pyrolysis properties of the carbon-containing matter and to measure biomass and microbial metabolism. They were compared to other soil properties such as total carbon and nitrogen, carbon to nitrogen ratio and pH. There was measurable organic matter in nine of the eleven samples and the heat of pyrolysis of those soils was correlated to the carbon content. In five of the eleven samples no biomass could be detected and the existence of basal microbial metabolism could not be established because all samples showed endothermic activity, probably from inorganic reactions with water. Six samples showed microbial activation after the addition of glucose. Carbon content, nitrogen content and the microbial activity after glucose amendment were correlated to the altitude and to the average minimum temperature of the sampling sites calculated from meteorological data. The detectable microbial metabolism was more dissipative with increasing altitude and decreasing temperature. [source] Arsenate toxicity for wheat and lettuce in six Chinese soils with different propertiesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2009Qing Cao Abstract To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves. Median effective concentration and 10% effective concentration values were derived with regression analysis to measure As toxic potencies, and no-observed-effect concentration was determined by comparison with a control to elucidate thresholds of As to the two plant species. The median effective concentration values for As varied from 159 to 683 mg/kg for wheat and 59 to 426 mg/kg for lettuce, and the 10% effective concentration values varied from 79 to 270 mg/kg for wheat and 20 to 156 mg/kg for lettuce. The result suggests that lettuce is a more sensitive species for monitoring soil As contamination. With the same level of As spiked, soil toxicity for a plant showed a tendency of fluvoaquic soil toward red soil or black soil toward paddy soil. The phytotoxicity of As was negatively correlated with soil amorphous iron content extracted with ammonium oxalate. The overall results from the present work illustrate the necessity of considering soil properties in assessing soil As contamination. [source] Avoidance tests in site-specific risk assessment,influence of soil properties on the avoidance response of collembola and earthworms,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2008Tiago Natal-da-Luz Abstract The ability of organisms to avoid contaminated soils can act as an indicator of toxic potential in a particular soil. Based on the escape response of earthworms and Collembola, avoidance tests with these soil organisms have great potential as early screening tools in site-specific assessment. These tests are becoming more common in soil ecotoxicology, because they are ecologically relevant and have a shorter duration time compared with standardized soil toxicity tests. The avoidance response of soil invertebrates, however, can be influenced by the soil properties (e.g., organic matter content and texture) that affect behavior of the test species in the exposure matrix. Such an influence could mask a possible effect of the contaminant. Therefore, the effects of soil properties on performance of test species in the exposure media should be considered during risk assessment of contaminated soils. Avoidance tests with earthworms (Eisenia andrei) and springtails (Folsomia candida) were performed to identify the influence of both organic matter content and texture on the avoidance response of representative soil organisms. Distinct artificial soils were prepared by modifying quantities of the standard artificial soil components described by the Organization for Economic Co-operation and Development to achieve different organic matter and texture classes. Several combinations of each factor were tested. Results showed that both properties influenced the avoidance response of organisms, which avoided soils with low organic matter content and fine texture. Springtails were less sensitive to changes in these soil constituents compared with earthworms, indicating springtails can be used for site-specific assessments of contaminated soils with a wider range of respective soil properties. [source] Evaluating the contribution of soil properties to modifying lead phytoavailability and phytotoxicity,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Elizabeth A. Dayton Abstract Soil properties affect Pb bioavailability to human and ecological receptors and should be considered during ecological risk assessment of contaminated soil. We used path analysis (PA) to determine the relative contribution of soil properties (pH, organic C [OC], amorphous Fe and Al oxides [FEAL], and cation-exchange capacity [CEC]) in modifying Pb bioavailability. The response of biological endpoints (bioaccumulation and dry matter growth [DMG]) of lettuce (Lactuca sativa) grown on 21 Pb-spiked (2,000 mg/kg) soils were determined. Lettuce tissue Pb ranged from 3.22 to 233 mg/kg, and relative DMG ranged from 2.5 to 88.5% of their respective controls. Simple correlation showed strong relationships between CEC and OC (p < 0.01) and weaker relationships between pH and FEAL (p < 0.05) and Pb bioaccumulation. Results of PA suggest that soil pH increased the negative surface charge of organic matter and clay, thereby increasing CEC and decreasing Pb bioaccumulation. Also, the direct effect of OC on tissue Pb can be attributed to formation of surface Pb complexes by organic matter functional group ligands. Increased OC and/or CEC reduced Pb solubility and bioavailability in the 21 soils in the present study. The relative importance of soil properties likely will vary between studies employing different soils. Soil properties should be considered during the ecological risk assessment of metal in contaminated soils. Path analysis is useful for ecological studies involving soils with a wide range of physicochemical properties and can assist in site risk assessment of metals and remediation decisions on contaminated sites. [source] Factors influencing the sorption of oxytetracycline to soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2005Aaryn D. Jones Abstract Veterinary antibiotics such as oxytetracycline (OTC) increasingly are found in the environment and often come into direct contact with soils via the release of animal wastes. Oxytetracycline is known to sorb strongly to soils by interaction with soil organic matter, clay minerals, and metal oxides. However, current knowledge of the influence of soil properties on OTC sorption is limited, as is our ability to predict OTC sorption to soils. This work was aimed at identifying properties that most influence the extent of OTC sorption in a suite of soils from the eastern United States representing a wide range in soil properties. Thirty soils were well characterized, an OTC soil-water distribution coefficient (Kd) was determined for each soil, and statistical analyses were employed to determine appropriate soil descriptors of OTC sorption. Soil texture, cation exchange capacity, and iron oxide content seemed to most influence the extent of OTC sorption in soils with organic carbon (OC) content between 0 and 4%. Thus, the knowledge of these three soil properties would be key to anticipating the extent of OTC sorption and gaining insight into OTC fate within a given soil system. Notably, OC content appeared to influence OTC sorption only in a soil with 9% OC. [source] Soil-solution speciation of CD as affected by soil characteristics in unpolluted and polluted soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2005Erik Meers Abstract Total metal content by itself is insufficient as a measure to indicate actual environmental risk. Understanding the mobility of heavy metals in the soil and their speciation in the soil solution is of great importance for accurately assessing environmental risks posed by these metals. In a first explorative study, the effects of general soil characteristics on Cd mobility were evaluated and expressed in the form of empirical formulations. The most important factors influencing mobility of Cd proved to be pH and total soil content. This may indicate that current legislation expressing the requirement for soil sanitation in Flanders (Belgium) as a function of total soil content, organic matter, and clay does not successfully reflect actual risks. Current legal frameworks focusing on total content, therefore, should be amended with criteria that are indicative of metal mobility and availability and are based on physicochemical soil properties. In addition, soil-solution speciation was performed using two independent software packages (Visual Minteq 2.23 and Windermere Humic Aqueous model VI [WHAM VI]). Both programs largely were in agreement in concern to Cd speciation in all 29 soils under study. Depending on soil type, free ion and the organically complexed forms were the most abundant species. Additional inorganic soluble species were sulfates and chlorides. Minor species in solution were in the form of nitrates, hydroxides, and carbonates, the relative importance of which was deemed insignificant in comparison to the four major species. [source] Impact of animal waste lagoon effluents on chlorpyrifos degradation in soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2000Xinjiang Huang Abstract Animal-derived lagoon effluents are a good source of inorganic nutrients and organic matter; however, they may impact the degradation and transport of soil-applied pesticides. The degradation of chlorpyrifos in poultry-, swine-, and cow-derived effluents and effluent-soil matrices were studied using batch and column incubation studies. Chlorpyrifos was degraded by aerobic microbial processes in animal-derived lagoon effluents. Microbial community analysis by denaturing gradient gel electrophoresis of polymerase chain reaction-amplified 16S ribosomal ribonucleic acid genes showed that a single band became dominant in effluent during chlorpyrifos degradation. In soils, both biotic and abiotic degradation contributed significantly to the overall dissipation of chlorpyrifos. Large differences in degradation rates were observed between soils, with the fastest rate observed in soil with higher pH and cation-exchange capacity. Effluents appeared to have only a minor effect on chlorpyrifos degradation in soils, although effluent-induced increases in soil-solution pH over time may enhance hydrolysis by a few percent in low-pH soils. Soil properties, not effluent properties, appear to control chlorpyrifos degradation under laboratory conditions; however, the impact on changes in soil properties and microbial ecology with long-term effluent irrigation warrants further investigation. [source] Estimating within-field variation using a nonparametric density algorithmENVIRONMETRICS, Issue 5 2006A. Castrignanò Abstract The application of site-specific techniques and technologies in precision farming requires subdividing a field into a generally small number of contiguous homogeneous zones. The proposed algorithm of clustering is based on nonparametric density estimate, where a cluster is defined as a region surrounding a local maximum of the probability density function. Soil samples were collected in a 2-ha field of the experimental farm of the Agricultural Research Institute, located in Foggia (Southern Italy) and some of the most production-affecting soil properties were interpolated by using the geostatistical techniques of kriging and cokriging. The application of the clustering approach to the (co)kriged surface variables produced the subdivision of the field into five distinct classes. The proposed algorithm proves quite promising in identifying spatially contiguous zones, which are more homogeneous in soil properties than the whole-field. Its great advantage consists in giving an additional description of the residual variation within the class and such a piece of information is very useful in precision farming as a basis for the variable-rate application of agronomic inputs. Copyright © 2005 John Wiley & Sons, Ltd. [source] Impact of common European tree species on the chemical and physicochemical properties of fine earth: an unusual patternEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2010L. Mareschal Case studies are necessary to assess the effects of changes to tree species on the physicochemical and chemical properties of soils. To achieve this, the fine earth under five tree species was investigated. This study was performed in the Breuil-Chenue experimental forest site located in the Morvan Mountains (France). This site contains two adjacent blocks with replicated stands. The native forest (old beech and oak coppice with standards) was partially clear-felled and replaced in 1976 with mono-specific plantations of European beech, Norway spruce, Laricio pine and Douglas fir. The same changes in soil properties were revealed in both blocks, thus confirming the tree species effect. The percentage of exchangeable acidity on the cation exchange capacity (CEC) was greater under spruce, Douglas fir and pine than under the other species. Spruce stands, and to a lesser extent those of Douglas fir and pine, had a less acidic soil pH than hardwood stands (which was unusual in view of the data in the literature) and smaller CEC values. The small quantities of carbon added to the soil under these tree species provide an explanation for these effects through a partial control of both CEC and pH. This case study thus demonstrated that the tree species effect was not unequivocal and different criteria are necessary for its interpretation. Tree species significantly influenced certain aspects of the chemical properties of topsoil and have the potential to have an impact on current soil fertility. [source] Partitioning of metals (Cd, Co, Cu, Ni, Pb, Zn) in soils: concepts, methodologies, prediction and applications , a reviewEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2009F. Degryse Summary Prediction of the fate of metals in soil requires knowledge of their solid,liquid partitioning. This paper reviews analytical methods and models for measuring or predicting the solid,liquid partitioning of metals in aerobic soils, and collates experimental data. The partitioning is often expressed with an empirical distribution coefficient or Kd, which gives the ratio of the concentration in the solid phase to that in the solution phase. The Kd value of a metal reflects the net effect of various reactions in the solid and liquid phases and varies by orders of magnitude among soils. The Kd value can be derived from the solid,liquid distribution of added metal or that of the soil-borne metal. Only part of the solid-phase metal is rapidly exchangeable with the solution phase. Various methods have been developed to quantify this ,labile' phase, and Kd values based on this phase often correlate better with soil properties than Kd values based on total concentration, and are more appropriate to express metal ion buffering in solute transport models. The in situ soil solution is the preferred solution phase for Kd determinations. Alternatively, water or dilute-salt extracts can be used, but these may underestimate in situ concentrations of dissolved metals because of dilution of metal-complexing ligands such as dissolved organic matter. Multi-surface models and empirical models have been proposed to predict metal partitioning from soil properties. Though soil pH is the most important soil property determining the retention of the free metal ion, Kd values based on total dissolved metal in solution may show little pH dependence for metal ions that have strong affinity for dissolved organic matter. The Kd coefficient is used as an equilibrium constant in risk assessment models. However, slow dissociation of metal complexes in solution and slow exchange of metals between labile and non-labile pools in the solid phase may invalidate this equilibrium assumption. [source] Organic carbon additions: effects on soil bio-physical and physico-chemical propertiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2009A. Bhogal Summary The effects of organic carbon (OC) additions from farm manures and crop residues on selected soil bio-physical and physico-chemical properties were measured at seven experimental sites, on contrasting soil types, with a history of repeated applications of farm manure or differential rates of inorganic fertilizer nitrogen (N). Repeated (> 7 years annual additions) and relatively large OC inputs (up to 65 t OC ha,1) were needed to produce measurable changes in soil properties, particularly physical properties. However, over all the study sites, there was a positive relationship between OC inputs and changes in total soil OC and ,light' fraction OC (LFOC), with LFOC providing a more sensitive indicator of changes in soil organic matter status. Total soil OC increased by an average of 3% for every 10 t ha,1 manure OC applied, whereas LFOC increased by c. 14%. The measured soil OC increases were equivalent to c. 23% of the manure OC applied (up to 65 t OC ha,1 applied over 9 years) and c. 22% of the crop residue OC applied (up to 32 t OC ha,1 over 23 years). The manure OC inputs (but not crop residue OC inputs) increased topsoil porosity and plant available water capacity, and decreased bulk density by 0.6%, 2.5% and 0.5% with every 10 t ha,1 manure OC applied, respectively. Both OC sources increased the size of the microbial biomass (11% increase in biomass C with 10 t OC ha,1 input), but only manure OC increased its activity (16% increase in the soil respiration rate with 10 t OC ha,1 input). Likewise, the potentially mineralizable N pool only increased with manure N inputs (14% increase with 1 t manure total N ha,1). However, these soil quality benefits need to be balanced with any potential environmental impacts, such as excessive nutrient accumulation, increased nitrate leaching and phosphorus losses and gaseous emissions to the atmosphere. [source] Spatial variation of ammonia volatilization from soil and its scale-dependent correlation with soil propertiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2008R. Corstanje Summary Quantitative predictions of ammonia volatilization from soil are useful to environmental managers and policy makers and empirical models have been used with some success. Spatial analysis of the soil properties and their relationship to the ammonia volatilization process is important as predictions will be required at disparate scales from the field to the catchment and beyond. These relationships are known to change across scales and this may affect the performance of an empirical model. This study is concerned with the variation of ammonia volatilization and some controlling soil properties: bulk density, volumetric water content, pH, CEC, soil pH buffer power, and urease activity, over distances of 2, 50, 500, and >2000 m. We sampled a 16 km × 16 km region in eastern England and analyzed the results by a nested analysis of (co)variance, from which variance components and correlations for each scale were obtained. The overall correlations between ammonia volatilization and the soil properties were generally weak: ,0.09 for bulk density, 0.04 for volumetric water content, ,0.22 for CEC, ,0.08 for urease activity, ,0.22 for pH and 0.18 for the soil pH buffer power. Variation in ammonia volatilization was scale-dependent, with substantial variance components at the 2- and 500-m scales. The results from the analysis of covariance show that the relationships between ammonia volatilization and soil properties are complex. At the >2000 m scale, ammonia volatilization was strongly correlated with pH (,0.82) and CEC (,0.55), which is probably the result of differences in parent material. We also observed weaker correlations at the 500-m scale with bulk density (,0.61), volumetric water content (0.48), urease activity (,0.42), pH (,0.55) and soil pH buffer power (0.38). Nested analysis showed that overall correlations may mask relationships at scales of interest and the effect of soil variables on these soil processes is scale-dependent. [source] Using soil knowledge for the evaluation of mid-infrared diffuse reflectance spectroscopy for predicting soil physical and mechanical propertiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2008B. Minasny Summary Mid-infrared diffuse reflectance spectroscopy can provide rapid, cheap and relatively accurate predictions for a number of soil properties. Most studies have found that it is possible to estimate chemical properties that are related to surface and solid material composition. This paper focuses on prediction of physical and mechanical properties, with emphasis on the elucidation of possible mechanisms of prediction. Soil physical properties that are based on pore-space relationships such as bulk density, water retention and hydraulic conductivity cannot be predicted well using MIR spectroscopy. Hydraulic conductivity was measured using a tension-disc permeameter, excluding the macropore effect, but MIR spectroscopy did not give a good prediction. Properties based on the soil solid composition and surfaces such as clay content and shrink-swell potential can be predicted reasonably well. Macro-aggregate stability in water can be predicted reasonably as it has a strong correlation with carbon content in the soil. We found that most of the physical and mechanical properties can be related back to the fundamental soil properties such as clay content, carbon content, cation exchange capacity and bulk density. These connections have been explored previously in pedotransfer functions studies. The concept of a spectral soil inference system is reiterated: linking the spectra to basic soil properties and connecting basic soil properties to other functional soil properties via pedotransfer functions. [source] Changes in shrinkage of restored soil caused by compaction beneath heavy agricultural machineryEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2008B. Schäffer Summary Compaction is a major cause of soil degradation. It affects not only the porosity of the soil, but also the soil's hydrostructural stability. Soil that is restored after temporary removal is particularly sensitive to compaction. We investigated the effects of trafficking with a heavy combine harvester on the shrinkage behaviour of a restored soil that had been gently cultivated for several years. We tested the hypothesis that compaction decreases the hydrostructural stability of restored soil by analysing simultaneously measured shrinkage and water retention curves of undisturbed soil samples. Shrinkage strongly depended on clay and organic carbon content. Taking account of this influence and normalizing the shrinkage parameters with respect to these soil properties, we found pronounced effects of trafficking on shrinkage. Ten passes with the combine harvester decreased the structural porosity by about 40% at maximum swelling and by about 30% at the shrinkage limit and increased the bulk density by 8% at maximum swelling and by 10% at the shrinkage limit, but did not significantly affect the porosity of the soil plasma. Moreover, trafficking modified shrinkage, increasing the slopes of the shrinkage curve in the basic and structural shrinkage domains by about 30% and more than 150% after 10 passes, respectively. Evidently the aggregate structure was strongly destabilized. The results indicate that the hydrostructural stability of the soil was still very sensitive to compaction by trafficking even 5 years after restoration. The analysis of shrinkage seemed well suited for the assessment of compaction effects on soil structure. [source] | |||||||||||||||||||||||||||||||