bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption of Cd(II) and Cu(II) by Na‐Montmorillonite at Low Surface Coverage
Authors: Inskeep William P. , Baham John 
Published: July 2010

AbstractMontmorillonite has a heterogeneous charge distribution, and it is important to determine whether constant potential edge sites or constant charge sites control metal adsorption. The pH dependence of metal adsorption provides insight into the adsorption mechanism as well as being an important variable that will determine the solubility of Cd or Cu in soil systems. Adsorption of Cu and Cd by Na‐montmorillonite (2 g L−1) in 0.01M NaClO4 was measured over a pH range from 4 to 8.5 under humidified N2 gas. With the exception of experiments for Cu adsorption > 10 µM CuT, total soluble metal values were undersaturated with respect to known metal hydroxide solid phases. Kinetics for the adsorption of 50 µM CdT and CuT were rapid, with equilibrium occurring within 30 min. Experimental data for initial metal concentrations ranging from 50 to 0.1 µM yielded linear adsorption isotherms over the pH value range studied. Initial metal concentrations represent from 6 to 0.01% of the total sites available for metal binding, assuming an average of 0.8 mmol charge g−1 of clay. The pH dependence associated with Cd and Cu adsorption was reversible and much lower than observed for oxide minerals or for precipitation reactions. Adsorption of 2 µM CdT by 2.0, 0.2, and 0.02 g of clay L−1 suspensions showed that the fractional coverage of Cd on montmorillonite increased when the solid concentration decreased. As the fractional coverage approached saturation on the calculated amount of constant potential edge sites, the pH dependence increased and approached expected values of pH dependent charge on constant potential sites. This suggests that constant potential edge sites may primarily be responsible for Cd and Cu adsorption at low adsorption densities.
Soil Acidity and Liming: II. Evaluation of Using Aluminum Extracted by Various Chloride Salts for Determining Lime Requirements
Authors: Oates Kenneth M. , Kamprath E. J. 
Published: July 2010

AbstractNeutralization of soil Al to a minimum value is one approach to liming acid soils. The objective of this study was to determine which chloride extracting solution removed the quantity of soil Al that readily reacts with limestone and reduces the Al saturation to < 15%. Soils were incubated for 8 weeks after being limed at rates needed to neutralize the Al removed by KCl, LaCl3, and CuCl2. Six soils with a range in organic matter contents were used. When the Al extracted by KCl was used to predict the lime rate, soils containing organic matter had a large amount of residual KCl‐extractable Al and a soil pH below 5.0. The lime rate predicted by the Al removed with LaCl3 reduced the residual Al to < 15% Al saturation for all soils. If residual Al is the criterion for evaluating limed soil, then LaCl3 is the best extracting solution. The LaCl3 not only removes the same amount of Al as KCl from the clay fraction of the soil, but also removes organically bound Al that influences the soil solution Al.
Relative Erodibility of 20 California Range and Forest Soils
Authors: Trott Kenneth E. , Singer Michael J. 
Published: July 2010

AbstractErodibility research on California upland soils has indicated that the Universal Soil Loss Equation's K nomograph may not account for all of the factors affecting erodibility of western upland soils. To further investigate this, laboratory rainfall simulation on 0.6‐ by 0.6‐m plots of sieved soil at 9% slope was used to measure relative erodibility of 20 upland soils, including two soils from terraces of the Sacramento River. The most powerful predictor in a stepwise multiple regression of erodibility, on a mass basis, was a combined smectite plus vermiculite clay mineralogy term. Also included in the four‐variable regression equation was bulk density, pyrophosphate‐extractable Fe + Al, and the standard texture term M. R2 for the equation was 0.800. Smectite plus vermiculite, M, a clay mineralogy‐pyrophosphate Fe + Al interaction term, pH, organic matter, oxalate Fe + Al, and vermiculite were the seven significant terms in the equation predicting soil loss on a volume basis. This equation had an R2 of 0.772. For now, the best available tool for predicting erodibilities of western upland soils appears to be the Universal Soil Loss Equation erodibility nomograph. However, results of this study show that because of the large differences in parent materials and soil‐forming conditions that distinguish midwestern from western soils, consideration of soil mineralogy in future predictive work may improve the predictive capacity of the nomograph.
Water Budget of an Eastern Deciduous Forest Stand
Authors: Luxmoore R. J. 
Published: July 2010

AbstractSoil water content and soil matric potential were monitored during 2 years at two neighboring ridge‐top sites in an oak‐hickory stand on a Typic Paleudult forest soil with cherty silt loam texture. Hydraulic gradients and soil water contents showed distinct seasonal variation. Soil water dynamics and water budgets were simulated with a soil‐plant‐atmosphere water flow model using meteorologic, soil, and plant characteristics estimated for the two sites. A seasonal pattern of soil water drainage and upward fluxes was predicted by the model that corresponded with the field‐determined hydraulic gradients. Recharge of water up into the root zone (0‐ to 90‐cm depth) from lower depths was predicted to contribute an average of 9 and 29% of the soil evaporation plus transpiration water loss at the two sites. Total evapotranspiration, including interception evaporation, was similar at the two sites; however, the greater upward water flux at one site compensated for the lower soil water capacity in the root zone at that site. There were significant differences between calculated and simulated daily drainage rates. Simulated soil water contents for the two study sites differed somewhat from measured values obtained on specific days. At longer time scales, the annual water budgets simulated for the sites were similar and were in reasonable agreement with measurements from a local watershed study. Annual evapotranspiration was predicted to be 74.5 cm for the ridge‐top forest stand, somewhat higher than the average of 70.5 cm estimated for the whole watershed.
Transformation of Incubated Micronutrient Chelates in Calcareous Soils
Authors: Ryan John , Hariq S. N. 
Published: July 2010

AbstractMicronutrient chelates have been introduced as fertilizing materials to overcome deficiencies mainly in calcareous soils, and to maintain effectiveness for a significant period of time. However, few studies have examined changes in applied chelates over a normal growing season, and some selected soil and environmental properties which influence these changes. Laboratory incubation studies, up to 168 d, were conducted to evaluate the influence of associated properties in several soils and, added CaCO3 (0, 2.5, 5.0, and 10.0% wt/wt), temperature (5, 15, 25, and 35°C) and wetting‐drying (up to four weekly cycles) on the persistence of applied FeEDDHA and Zn‐, Mn‐, and CuEDTA. Incubated samples were extracted with water and then with DTPA‐extraction solution. Recovery varied with the metals in each soil. After 168 d, 32 to 56% of the applied Fe and <13% of the applied Cu and Zn was extracted by both solutions. Loss of Mn from MnEDTA was essentially complete within 2 d. Decreased metal extractability appeared to be related to the organic matter content of each soil. Applied CaCO3 depressed recovery with no significant difference between application rates. Metal extraction also decreased consistently with increasing temperature and with the number of wet‐dry cycles compared to constantly moist samples. The results have implications for arid‐region soils where chelates are used under irrigation and high soil temperatures.
Linearized Moisture Flow with Root Extraction Over Two‐Dimensional Zones
Authors: Warrick A. W. , Lomen D. O. 
Published: July 2010

AbstractA solution of Richards' equation is developed for flow from a two‐dimensional, rectangular source or sink. The soil is assumed uniform with the unsaturated hydraulic conductivity exponentially related to pressure head. Steady‐state conditions are used, although a time‐dependent solution is discussed. The results are useful for approximating any two‐dimensional, explicitly defined root extraction pattern. This is possible by superimposing several rectangles to give the desired effect. Calculations are rapid with negligible computer time. Several examples are given appropriate for trickle irrigation, including stratified uptake regions, noncontiguous extraction zones, and a nonsymmetric case.
Adsorption of Oxamyl and Dimecron in Montmorillonite Suspensions
Authors: Bansal O. P. 
Published: July 2010

AbstractAdsorption of oxamyl and phosphamidon (Dimecron) was determined from dilute solutions of montmorillonite saturated with different cations, e.g., Li+, Na+, K+, Cs+, Fe3+, and Al3+. Adsorption of oxamyl was found to be greater than adsorption of Dimecron. The shapes of the isotherms depended on the exchangeable cations. The adsorption varied directly with the polarizing power of the exchangeable cation and inversely with changes in temperature, organic matter, and ionic strength up to 0.6, after which it became constant. The enthalpy changes (ΔH°) calculated from the temperature coefficient of the equilibrium constant showed that the process is exothermic. The adsorption of pesticides on montmorillonite gives rise to an entropy loss that is higher for trivalent cations. Various studies, e.g., infrared (IR) and x‐ray, as well as thermodynamic parameters and Freundlich adsorption isotherms, revealed the existence of protonation or coordination (or both) between exchangeable cations of clay and oxygen of > C=0 group of the pesticides. However, desorption studies showed the presence of physical adsorption.
Trace Metal Chemistry in Arid‐Zone Field Soils Amended with Sewage Sludge: III. Effect of Time on the Extraction of Trace Metals
Authors: Sposito Garrison , LeVesque C. S. , LeClaire Joseph P. , Chang A. C. 
Published: July 2010

AbstractThe surface horizons of two arid‐zone field soils that either had received amendments of composted sewage sludge annually since 1975, or had received amendments of liquid sludge between 1976 and 1978, were fractionated by sequential extraction for 4 years annually, beginning in 1979, to compare the solid‐phase forms of Ni, Cu, Zn, Cd, and Pb. The total concentration of each trace metal in the soils continually receiving composted sludge increased with time, whereas the total concentration of the metals in the soil that had received liquid sludge until 1978 did not increase with time. Regardless of the time variation of total metal concentration, the percentages of the metals in either the EDTA (ethylenedinitrilote‐traacetic acid)‐extractable fraction or the HNO3‐extractable fraction often tended to increase with time in the soils. This trend was more evident in the lighter‐textured field soil receiving composted sludge. It was concluded that the observed increase in EDTA‐extractable trace metals with time could be the result of the formation of trace metal carbonates accompanying the gradual mineralization of the organic matter in the applied sludge in the soil environment.
Changes in Phosphorus Adsorption Associated with Aging of Aluminum Hydroxide Suspensions
Authors: Sims J. T. , Ellis B. G. 
Published: July 2010

AbstractPhosphorus adsorption by “pure” Al‐OH suspensions was examined as a function of pH of Al‐OH precipitation, length of incubation, and ionic strength. Changes in P adsorption were measured through use of Langmuir isotherms after 30, 180, and 365 d of incubation. Physical characterization of changes in the Al‐OH suspensions was accomplished through x‐ray diffraction and scanning electron microscopy. Aging of Al‐OH suspensions reduced their capacity for P adsorption, and while Al‐OH precipitated at pH 5.5 initially adsorbed more P than that precipitated at pH 7.0, the difference became insignificant within 90 d. Reducing the ionic strength of the Al‐OH suspensions by dialysis produced gibbsite and caused a decrease in the P adsorption maxima (Langmuir b value), further evidence that the polymerization/crystallization process is an important control of Al‐OH reactivity for P.
The Effect of Temperature on Decomposition at Optimum and Saturated Soil Water Contents
Authors: Clark M. D. , Gilmour J. T. 
Published: July 2010

AbstractA laboratory study was conducted to evaluate the effect of temperature on decomposition in a silt loam soil under saturated (0.32 g/g) and optimal (0.19 g/g) soil water contents. Sewage sludge was the carbon substrate. Cumulative CO2‐C data were obtained for three temperatures (14, 22, and 30°C), and two substrate groups (rapid, intermediate) for the saturated and optimal water contents. Decomposition followed first‐order kinetics. The temperature effect for each substrate and water content was described by regressing the natural logarithm of the first‐order rate constant on the inverse of the absolute temperature. No significant differences in slopes between substrates within a water content were found for these regressions. Slopes were significantly different between water contents. The slopes were −8975 and −2660 K for the unsaturated and saturated soils, respectively. At saturation the much smaller rate of change in the rate constant, k, with temperature (slope) indicated that temperature had a much smaller influence on decomposition rate under saturated than under unsaturated conditions. Intercepts from the above regressions were significantly different between substrates and water contents. For the unsaturated soil, intercepts were 25.86 and 29.41 for the rapid and intermediate substrates, respectively. Parallel intercepts at saturation were 3.48 and 2.36, respectively. Differences in intercepts between water contents combined with slopes resulted in smaller k values for the saturated soil. These results pointed out that a single equation describing the effect of temperature on the first‐order rate constant should not be applied to the decomposition of organic matter in both unsaturated and saturated soils.
Complementary Methodologies to Delineate the Composition of Rhizobium trifolii Populations in Root Nodules
Authors: Dughri M. H. , Bottomley P. J. 
Published: July 2010

AbstractThree methods of strain identification were used to determine the composition of the Rhizobium trifolii population in nodules formed on subterranean clover (Trifolium subterraneum L. cv. Mt. Barker) inoculated with a soil suspension. Sodium dodecyl sulfate polyacrylamide gradient gel electrophoresis (SDS‐PAGGE) was used in a microslab system to elucidate the protein profiles of 22 isolates of R. trifolii. Tube agglutination serological tests carried out with antisera raised to four isolates showed that four groups of isolates could be recognized. Only four isolates out of 22 agglutinated with more than one antiserum, although they reacted with only one antiserum in the gel‐immune‐diffusion test. One isolate did not react with any of the four antisera. No group of isolates dominated the nodule population. Gel‐immune‐diffusion analysis showed that isolates from two of the four groups were serologically identical whereas isolates from the other two groups were serologically heterogeneous. Isolates within all four serogroups were subdivided further according to their protein profiles. Many of the isolates within individual groups had very closely similar or identical profiles whereas others were very distinct. Isolates identified as very similar or identical by SDS‐PAGGE had the same symbiotic effectiveness on T. subterraneum. The data illustrate the need for multiple methods of identification for the best delineation of the composition of the nodule population.
Effect of Entrapped Air on ECa vs. ECw Calibration Curves as Measured in a Soil Column
Authors: Frenkel H. , Nadler A. , Shainberg I. 
Published: July 2010

AbstractMeasurements of soil electrical conductivity, ECa, for assessing soil solution salinity, ECw, use calibration curves obtained in the field or in the laboratory. It has been found that calibration curves obtained in the laboratory on water‐saturated soil columns are very sensitive to entrapped air which affects the calibration slope of ECa − ECw by 25% or more. This difference in the slope is as large as the difference in slopes between soils having 25 and 50% clay. Displacing the entrapped air with CO2 before saturation reduces the problem and produces a more accurate calibration curve.
Two Types of Soil Anisotropy Induced by the Passage of a Wetting Front
Authors: Dexter A. R. 
Published: July 2010

AbstractDisks of soil were wetted from a point on their diameters. The tensile strength of the soil disks was measured using the Brazilian crushing test. Tensile strength was measured both in the direction of wetting and at right angles to the direction of wetting. These values were different, which indicated that the passage of the wetting front had made the soil anisotropic. The soil tensile strength was smallest either in the direction of wetting or at right angles to it. Some possible consequences of these changes for the processes of formation of natural soil structures are discussed.
Soil Test Calibration for Establishment of Turfgrass Monostands
Authors: Turner T. R. , Waddington D. V. 
Published: July 2010

AbstractLittle information is currently available relating fertilization and soil fertility to turfgrass establishment response. A field study was conducted on Hagerstown soil (fine, mixed, mesic, Typic Hapludalf) to determine the effects of seedbed applications of P, K, and limestone on establishment rate and quality of monostands of ‘Baron’ Kentucky bluegrass (Poa pratensis L.), ‘Atlanta’ Chewings fescue (Festuca rubra var. commutata Gaud.), and ‘Pennfine’ perennial ryegrass (Lolium perenne L.) Phosphorus applications ranged from 0 to 8.0 kg/are (1 are = 100 m2), potassium from 0 to 15.2 kg/are, and limestone from zero to 122.0 kg/are. Initial soil test levels were pH 5.7; 60 kg/ha of P; and 0.18, 0.7, and 4.3 cmo (p+)/kg of K, Mg, and Ca, respectively. Phosphorus additions to this soil had the most important effect on turfgrass establishment. The initial soil level of 60 kg/ha not sufficient for rapid turfgrass establishment. Seedbed P applications in the range of 1.6 to 4.0 kg P/are, resulting in soil P levels of approximately 110 to 180 kg/ha, proved to be most satisfactory in promoting rapid establishment as determined by turfgrass chemical composition, ground cover, clipping yield, and quality. Differences due to P tended to diminish with time, indicating that where rapid establishment is not critical, 60 kg/ha of P in this soil may be sufficient to obtain satisfactory stands of the species investigated. The initial pH, K, and Ca levels were sufficient for satisfactory turfgrass establishment on this soil. Limestone applications did not affect ground cover, tended to reduce initial clipping yields, had little influence on turfgrass quality, slightly reduced sod strength, and generally did not greatly affect tissue Ca levels. Potassium applications either reduced or had no effect on initial ground cover and had little effect on turfgrass quality. Although tissue K was substantially increased by K applications, tissue K levels of all three species on plots not fertilized with K were still much higher than levels generally considered critical or deficient.
Soil Genesis in a Natrargid‐Haplargid Complex in Northern Montana
Authors: Munn L. C. , Boehm M. M. 
Published: July 2010

AbstractClassical theory of the genesis of Natargids (solonetz) involves the upward movement of sodium from a water table. Examination of 24 pedons representing four Soil Series developed in glacial till on the Northern Great Plains (Montana) suggests that Natrargids (solonetz and solodized‐solonetz) and Haplargids (soloth) can develop in the absence of a water table. The four soils occur as a complex on “panspot” rangeland with the soloth and solodized‐solonetz on microknolls and the solonetz in microdepressions. The panspot soils have significantly (p = 0.01) greater B horizon clay contents than associated non‐panspot soils. X‐ray diffraction analyses indicate decomposition of smectite inherited from the parent material in the sola of all soils. Solonization of the panspots is driven by reduced infiltration and subsurface water movement in response to matric and osmotic potential gradients. Panspots occur over high points in the till‐shale boundary where the wetting front penetrates into the salty, calcareous till. Movement of sodium upwards from the shale contact results in dispersion of the panspot B horizon. Natric horizon development causes reduced infiltration and subsurface interpedon translocation of water, salts, and amorphous materials.
Mast Anchor for Hydraulic Soil‐Sampling Machines
Authors: Mielke L. N. , Wilhelm W. W. 
Published: July 2010

AbstractCurrently, hydraulic soil coring machines allow rapid sample collection to a desired depth under ideal soil conditions; however, under less desirable conditions, sampling can be very time consuming, unsafe, or, at times, impossible. An apparatus was designed and constructed that can be attached to the mast of hydraulic soil sampling machines to anchor the machines to the soil, thus permitting soil sampling when vehicle weight is insufficient to sample to a desired depth. The mast anchor system described is faster and easier to use than the standard system presently used with many hydraulic sampling machines. The parts of the apparatus were an auger, hydraulic motor, guide‐rail frame, slotted‐auger plate, and hydraulic valve and hoses. In one soil sampling situation without additional anchorage, 76.2‐mm diam samples were obtainable to a depth of only 0.75 m, whereas with either standard or mast anchoring, samples were collected to 1.20 m. However, standard anchoring procedures required from 8 to 10 min to install and remove at each sample location, whereas the mast anchor required < 0.5 min.
Enhancement of Thermal Water Vapor Diffusion in Soil
Authors: Cass A. , Campbell G. S. , Jones T. L. 
Published: July 2010

AbstractThe enhancement of water vapor diffusion in soil resulting from a temperature gradient was determined using a transient state thermal conductivity measurement. The method of Parikh et al. (1979) was adapted for this study to allow measurement of the thermal conductivity as a function of temperature, water content, and pressure. The data allowed separation of thermal conductivity from thermally induced latent heat transport. Both the mechanistic enhancement factor η of Philip and de Vries and the phenomenological enhancement factor β of Cary are calculated from the slope of the relationship between thermal conductivity and reciprocal relative pressure. The enhancement factor, η approaches 1 for dry soil and increases rapidly to values around 10 for a sand and a silt loam at water contents above half saturation and temperatures above 22°C. At high water content and 3.5°C, η increased to 15. The inflection point water content for the η vs. saturation curve was about twice as high in silt loam as in sand. Measurements conform well to the pattern predicted by a theoretical examination of enhancement factor behavior. Experimental results were also compared with two recent quantitative models of β from Jury and Letey (1979) and Cary (1979). These model predictions did not agree with measured values, nor did they conform to the theoretical limits of β derived in this paper except at intermediate saturation and temperature values.