bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Laboratory Technique for Appraising in Situ Salinity of Soil
Authors: Mubarak A. , Olsen R. A. 
Published: July 2010

AbstractA laboratory technique has been devised for removal of solution from soils at field water content. A soil sample can be placed directly in a closable centrifuge tube, thereby minimizing changes which could be induced by altering gaseous equilibria. Water need not be added to the soil sample, so changes in electrical conductivity (EC) and in concentration of species present are avoided. The soil solution is obtained from the sample by immiscible displacement with CCl4 using centrifugation. The technique is simple and relatively rapid. Values for EC in successively displaced solution samples from a given soil sample were found to be essentially constant. The values for EC obtained for an assortment of soils were significantly higher than those obtained using 2:1 or saturation extracts but were well correlated with them.
Salt Effects on the Hydraulic Properties of a Swelling Soil
Authors: Dane J. H. , Klute A. 
Published: July 2010

AbstractThe effects of soil solution composition on the hydraulic conductivity (K) and the volumetric soil solution content (θ) were measured with mixed NaCl‐CaCl2 solutions. The total electrolyte concentration (C) and the sodium adsorption ratio (SAR) characterized the applied solutions. Steady‐state flow cells were constructed with provision for (i) measurement of the volumetric flux of the solution phase during saturated and unsaturated flow conditions, (ii) measurement of the volumetric soil solution content by gamma attenuation, (iii) tensiometers for hydraulic gradient and pressure head (h) measurement, (iv) application of an external load on the soil, and (v) measurement of bulk volume changes. Soil samples were subjected to sequences of solutions varying in C from 1,000 meq/liter to 10 meq/liter at constant SAR values of 0, 5, 15, 25, and 40, respectively. Hydraulic conductivity decreases occurred during the first sequence of decreasing C at fixed SAR values equal to or > 5. The higher the SAR value, the greater the decrease in K with decreasing C. The K decreases occurred at all volumetric soil solution contents within the range of experimental data. Increases in θ, at given h values, and decreases in bulk density (ρb), occurred simultaneously with the decreases in K. Greater changes in K and θ, and smaller changes in ρb occurred in the soil subjected to a higher external load. The K and ρb decreases and the θ increases were to a great extent irreversible, i.e. when C was subsequently increased at a fixed SAR value, K, ρb, and θ did not regain their initial values. Substantial increases in K were obtained, however, if the soil was air dried, sieved, and repacked into the flow cell.
Solute Distribution Profiles Computed with Steady‐State and Transient Water Movement Models
Authors: Wierenga P. J. 
Published: July 2010

AbstractA comparison is made between two numerical models for simultaneous movement of water and salts in soil profiles. In the first model the water content and flux are constant during irrigation with time or depth (steady state model). In the second model the water contents and fluxes change with time and depth following each infiltration according to the hydraulic properties of the soil (transient model). From a comparison between data obtained with the two models, it is shown that both techniques yield comparable results when concentrations are plotted versus cumulative drainage. Measured effluent concentration distributions from columns periodically irrigated with labeled water, also compare well with effluent concentration distributions computed with the steady‐state model.
Heat Transfer in Dry Aggregated Soil: I. Heat Conduction
Authors: Hadas A. 
Published: July 2010

AbstractThe thermal conductivities of aggregated soils were determined experimentally in the laboratory. As expected the thermal conductivity decreases as the size of the aggregates and the total and interaggregate porosities increase. Good agreement between the measured and predicted thermal conductivity values, by two methods, was found only for small aggregates, but failed increasingly as the aggregate size increased. The discrepencies between measured and predicted values are discussed and are attributed to thermal contact resistance between the soil aggregates that increases as the size and the numbers of the contact points for the aggregates decreases.
Ammonia Volatilization From Soils: Equilibrium Considerations
Authors: Avnimelech Yoram , Laher Malka 
Published: July 2010

AbstractThe volatilization of ammonia from soils as a function of the system's properties is analyzed theoretically and experimentally. The final concentration of ammonium held by the soil increases with an increase in hydrogen ion activity, with the initial ammonium concentration, and with partial pressure of ammonia in the air. An increase in the buffer capacity of the soil leads to a decrease in the final ammonium concentration.A good agreement has been found between measured and computed values for NH3 and NH4 concentrations during the process.The pH of the soil is the dominant factor controlling the extent of ammonia volatilization only when the soil's buffer capacity is high, or, when the concentration of ammonium in the soil is low. At high pH and high initial ammonium concentrations, the dominant factor controlling the reaction is the buffer capacity of the soil.
Estimated Association Constants for Some Complexes of Trace Metals with Inorganic Ligands
Authors: Mattigod Shas V. , Sposito Garrison 
Published: July 2010

AbstractChemical equilibrium studies of trace metals in soils by an ion‐association model require reliable data on thermodynamic association constants for various metal‐ligand complexes. Therefore, available experimental data at 25°C were compiled for complexes of the transition metal cations Mn2+, Fe2+, Nl2+, Cu2+, and Zn2+ with the ligands CO32‐, HCO3‐, SO42‐, HSO4‐, PO43‐, HPO42‐, H2PO4‐, Cl‐, and OH‐. However, experimental values of the thermodynamic association constants for many of the complexes were not available. This lack of information was alleviated by employing the theoretical model of Kester and Pytkowicz and the semiempirical models of Nieboer and McBryde, and Van Panthaleon Van Eck to make estimates of the as yet unmeasured association constants. These estimated constants were tabulated in a compact form along with the experimental values. This compilation of 100 association constants, although provisional, should prove helpful in a variety of studies on trace metal equilibria in soils until more reliable experimental data become available.
Pyrolysis‐Gas Chromatography‐Mass Spectrometry of Soil Humic Fractions: I. The Low Boiling Point Compounds
Authors: Martin F. , Saiz‐Jimenez C. , Cert A. 
Published: July 2010

AbstractPyrolysis‐gas chromatography‐mass spectrometry studies of fulvic and humic acids from different soils: Calcic Rhodoxeralf, Typic Xerochrept, Typic Chromoxeret, Andic Hapludult, Humic Haplorthod, Typic Haplorthod and a Canadian Orthic Humo‐Ferric Podzol were made. Samples were pyrolyzed at 700°C for 10 sec, and low boiling point compounds were separated in a Chromosorb 102 column. Peaks were identified with a mass spectrometer coupled to the gas chromatograph. Major components from soil humic acids were related to proteins, namely methane, ethene, ethane, propene, propane, butene, acetonitrile, benzene, pyridine, pyrrol, toluene, and phenol, and to polysaccharides, such as acetaldehyde, acetone, furan, methylfuran, 2‐butanone, and furfural. Soil fulvic acids gave pyrograms with major peaks of methane, ethene, acetaldehyde, acetone, furan, acetic acid, 2‐butanone, benzene, toluene, and furfural, which are characteristic for soil polysaccharides. Bromomethane, an unusual compound, was found in the humic fractions from podzolic soils.
Soil Inventory From Digital Analysis of Satellite Scanner and Topographic Data
Authors: Weismiller R. A. , Persinger I. D. , Montgomery O. L. 
Published: July 2010

AbstractA soil inventory of Chariton County, Missouri was prepared using computer‐aided analysis of Landsat Multispectral scanner (MSS) data to determine how spectral soil maps produced by digital analysis of satellite MSS data can accelerate and improve the quality of the National Cooperative Soil Survey Program.Landsat data collected on 15 Apr. 1974 were spatially registered at a scale of 1:24,000 and overlaid with ancillary data in the form of digitized township, watershed, and physiographic boundaries. The county was classified into 30 spectrally separable classes using computer‐implemented pattern recognition techniques. Approximately 64% of the county was identified as bare soil and was classified into 14 spectrally separable soil classes. The remaining 36% was classified as forest, pasture, and close‐grown crops.The digitized boundary data allowed the computer to manipulate, compile, extract, and present spectral class information within topographic or political units. The physiographic boundaries were used to delineate three landscape positions of interest: (i) bottomlands, (ii) gently sloping uplands, and (iii) moderately steep uplands. These delineations allowed the computer to differentiate between spectrally similar soils which occur on distinctively different landscape positions. Spectral classes of soil were correlated with individual soil series and taxonomic classifications for both the bottomland and uplands units.While a spectral classification of soils alone cannot distinguish between widely different soils exhibiting similar spectral responses, it can aid in identifying meaningful divisions of soils. By combining digitized ancillary data with MSS data, a more detailed delineation of soils can be provided as compared to information derived solely from MSS data. Further refinement of this technique will continue to increase the usefulness of satellite MSS data as an aid in soil survey.
Estimation of the Amount of Amorphous Materials for Characterizing Andosols
Authors: Kawai Kanji 
Published: July 2010

AbstractAn estimation method of amorphous inorganic materials in soils for characterizing andosols and tentative criteria for classification of andosols was proposed. Organic matter‐free fine earth is treated with 0.2N oxalic acid solution at 40°C for 6 hours under about 10,000 lux by a fluorescent lamp. The amounts of extracted silica, aluminum, and iron are highly correlated with values determined by the alternate dissolution method using hydrochloric acid and sodium hydroxide solutions.Andepts have more than 50% of amorphous inorganic materials in the clay fraction as determined by the pipette method after treated by ultrasonic vibration. The soils, derived from volcanic ash and/or volcanic ash influenced or redeposited, containing < 50% of amorphous inorganic materials in the clay fraction and < 20% on an ovendry basis, are included in Andeptic subgroups.
Fate of Fertilizer Nitrate Applied to Coastal Bermudagrass on a Swelling Clay Soil
Authors: Kissel D. E. , Smith S. J. 
Published: July 2010

AbstractThe purpose of this study was to determine why N fertilizer recovery by Coastal bermudagrass (Cynodon dactylon L.) is lower on swelling clay soils than on coarse‐textured soils. The disposition of N fertilizer applied to Coastal bermudagrass in the field over two growing seasons was determined by applying 560 kg N/ha as Ca(NO3)2 tagged with 7.599 atom % 15N to a field microplot during 1974 and measuring various components of the N balance. Plant uptake of residual N was measured during 1975.Forty‐nine percent of the applied N was recovered in harvested forage in 1974. About 40% of the applied N remained in the soil as residual N at the end of 1974. About 10% of the N was unaccounted for, indicating that denitrification losses were no more than 10% of the applied N. Most of the residual N at the end of the first growing season was immobilized N or was present in the root system of the grass. Immobilization is, therefore, a major factor causing low recovery of applied N by Coastal bermudagrass on swelling clay soils. Moreover, since only 17% of the residual N was recovered in forage during 1975 (7% of the N applied in 1974), most of the immobilized N was not available the following year.
Importance of the Organic Phosphorus Fraction in Extracts of Calcareous Soil
Authors: Abbott J. L. 
Published: July 2010

AbstractLaveen clay loam soil samples were collected immediately following the harvest of forage sorghum [Sorghum bicolor (L.) Moench]. Two sets were prepared before growing turnips (Brassica rapa L.) as the test crop in the greenhouse. One set was without treatment and the other, to simulate winter and spring conditions, was incubated for 20 days after addition of N and dextrose. Phosphorus uptake by turnips and changes in soil P forms were positively correlated with corresponding measurements taken during the growth of the sorghum crop. With this as a basis, the effect appears to be similar to that which occurs in the field on the immobilization and mineralization of available P. Inorganic and total soil P were determined in extracts obtained by five procedures. Correlations among P uptake by forage sorghum, turnips, and soil P measurements indicated their value in predicting available P. Prediction values for two of the procedures were improved by including the extractable organic P with the inorganic P for the incubated soil. Results showed that (i) time of sampling, (ii) the crop to be grown, (iii) the method of extraction, and (iv) the means of converting organic P to a measurable inorganic form in the extract are of prime concern in deciding when to include extractable organic P in the P evaluation of a given soil.
Residual Effects of Calcium Silicate in Tropical Soils: I. Fate of Applied Silicon During Five Years Cropping
Authors: Khalid R. A. , Silva J. A. , Fox R. L. 
Published: July 2010

AbstractA field experiment was conducted at the Kauai Branch Station to study the long‐term effects of calcium silicate applied to a Gibbsihumox soil. The fate of applied Si was determined during 5 years of cropping at one P (280 kg/ha) and three pH levels (5.5, 6.0, and 6.5). Plant uptake by the sugarcane plant (Saccharum officinarum L.) and ratoon crops, corn, (Zea mays L.), and seven harvests of kikuyugrass (Pennesetum clandestinum H.) accounted for 12 to 21% of the applied Si. Repeated extraction of profile samples taken at the end of 5 years with 0.1N acetic acid adjusted to pH 3.5 and containing 50 ppm P recovered 14 to 28% of the applied Si. There was no evidence that applied Si moved below the 30‐cm soil depth. This indicated that 57 to 72% of the applied Si remained in the soil in some fixed form not readily displaced by phosphate solution. Water‐soluble Si and plant uptake of Si decreased as pH increased while phosphate‐extractable Si increased as pH increased.
Oxygen Isotopic Ratios of Quartz from Wind‐Erosive Soils of Southwestern United States in Relation to Aerosol Dust
Authors: Sridhar K. , Jackson M. L. , Clayton R. N. , Gillette D. A. , Hawley J. W. 
Published: July 2010

AbstractThe oxygen isotopic ratios (expressed as parts per thousand relative to mean ocean water, SMOW, δ18O) of the quartz from 13 soils undergoing much wind erosion during the study period of 1972–1975 in four southwestern states and from comparison areas were determined. The δ18O for quartz from eight Texas (TX) and Arizona (AZ) soils range from 13.0 to 15.9 ‰. The quartz of the sands and silts coarser than 20 µm from three of the soils had δ18O values ranging from 13.1 to 15.1 ‰, characteristic of an ultimate igneousmetamorphic origin. The δ18O values increase greatly with decreasing particle size of quartz from three soils ranging from loamy fine sand to loam to clay in texture. The δ18O of the 1–10 µm quartz fraction (aerosol size) ranged from 19.2 to 20.2 ‰ (19.55 ± 0.28 ‰; ± sigma) for the thirteen soils most affected by dust storms. The higher values are suggestive of an admixture of some quartz crystallized at low temperature to quartz of high temperature origin. These results are not significantly different from the mean of 20.73 ± 1.82 ‰ found earlier for the same fraction from 30 shales of the midcontinental United States, but are 4 to 7 ‰ higher than those reported for New Zealand, Australian, and southern African soils. The 1–10 µm quartz from the comparison areas of TX and AZ soils in Fluvial materials further southeast and southwest has a δ18O mean of 17.7 ± 0.6 ‰, reflecting the influx of a slightly higher proportion of quartz from igneous sources than in the soils most affected by wind erosion. The oxygen isotopic ratios of 1–10 µm quartz from three Hawaiian soils and two sediments from Lake Waiau occurring at 3,970 m altitude on the Mauna Kea summit on the Island of Hawaii give a δ18O mean of 18.3 ± 0.2 ‰. Quartz of the above soils, including sandy, loamy, and clayey soils of southwestern United States, in addition to shales reported earlier, are source reservoirs of quartz having intermediate oxygen isotopic ratios characteristic of mixtures of two sources of quartz, one crystallized at high (e.g., δ18O = 11 ‰) and one at low temperature (e.g., δ18O = 30 ‰).
Pertinent Criteria for Describing the Dissolution of Gypsum Beds in Flowing Water
Authors: Keisling T. C. , Rao P. S. C. , Jessup R. E. 
Published: July 2010

AbstractThe equation for convective‐dispersive solute transport in porous beds and the continuity equation were used to derive a relationship describing the dissolution of gypsum beds in flowing water. The parameters involved in the derived relationship were: bed length, solution flow velocity, dispersion coefficient, mass transfer rate coefficient, and gypsum fragment size. The proposed relationship was compared with previously published data and shown to be valid. A potential practical field application of the procedure is presented.
Adsorption of Aldicarb By Clays and Soil Organo‐Clay Complexes
Authors: Supak James R. , Swoboda Allen R. , Dixon Joe B. 
Published: July 2010

AbstractAdsorption experiments conducted with S‐methyl‐14C‐aldicarb resulted in what appeared to be negative adsorption (exclusion) of the toxicant on Ca− and Al− saturated montmorillonite clays. Calculated exclusion volumes indicated that aldicarb did not penetrate the interlamellar region. Aldicarb was excluded from at least the first 16 layers of water on external surfaces of montmorillonite. Positive adsorption occured with Ca− and Al− saturated illite and kaolinite clays. Equilihration of aldicarb solutions with one acid and two calcareous Vertisols, and with the organo‐clay complexes isolated from these Vertisols, produced negative adsorption isotherms for the acid and positive adsorption isotherm for calcareous adsorbents.
An Improved SMP Soil Lime Requirement Method Incorporating Double‐Buffer and Quick‐Test Features
Authors: McLean E. O. , Eckert D. J. , Reddy G. Y. , Trierweiler J. F. 
Published: July 2010

AbstractThe double‐buffer (DB) feature of the recently‐published Yuan method was applied to the Shoemaker‐McLean‐Pratt (SMP) method at several buffer pH levels, shaking times, and soil/solution ratios. The results, based on regression analysis of buffer‐indicated vs. Ca(OH)2‐titrated acidities, indicate that the widely used SMP single‐buffer (SB) method can be improved considerably by incorporation of DB, quick‐test, and mathematical‐adjustment features. However, the SMP‐SB method is still probably the most satisfactory compromise between simplicity of measurement and reasonable accuracy of results for soils of a wide range in lime requirement (LR). The SMP‐DB method with narrow soil/solution ratio and shorter shaking time gave excellent indication of soil LR when adjusted for incomplete reaction with the soil during the shorter “quick‐test” reaction time. This adaptation which looks very promising as an improved method (especially for use on soils of low LR where the SMP‐SB method is known to lack desired accuracy) is included as a recommended improvement of the SMP‐SB method.
Failure Sequence of Gully Headwalls in Western Iowa
Authors: Bradford J. M. , Piest R. F. , Spomer R. G. 
Published: July 2010

AbstractA characterization of the failure sequence of gully headwalls and banks is necessary to predict gully erosion rates and to develop controls. A model is given for the sequential nature of gully growth in the thick loessial area of western Iowa. The failure sequence includes a popout or alcove failure near the toe of a near‐vertical wall, columnar sloughing of the overhanging material, and finally the transport of the eroded material downstream. The initiating failure at the base of the wall is a result of weakening of the soil material by wetting. The gully bank failure sequence and geometry in the western Iowa loess region is compared to gully erosion studies in the glacial drift region of northwestern Missouri and in the Piedmont of South Carolina.
Extraction of Soil Solution Using a Simple Centrifugation Method for Pesticide Adsorption‐Desorption Studies
Authors: Dao T. H. , Lavy T. L. 
Published: July 2010

AbstractA simple and rapid centrifugation technique has been devised to extract small samples of soil solution from moist pesticide‐treated soils to allow measurement of the pesticide equilibrium concentration. Energy status of the soil water extracted was characterized by correlating the amount of centrifugal force applied, soil moisture content, and matric potential. By varying the size of soil samples and the centrifugal force applied, a sizable volume of soil solution (40 to 53% of the moisture content at or below 0.3 bar suction) was obtained from the soil. The pesticide equilibrium concentration of the soil solution remained relatively constant throughout the centrifugation process.
Leaching Characteristics of a Layered Field Soil
Authors: Starr J. L. , DeRoo H. C. , Frink C. R. , Parlange J.‐Y. 
Published: July 2010

AbstractTwo ponded flow experiments were conducted to study the leaching characteristics of a layered field soil, fine sandy loam over coarse sand, with a water table at a depth of 1.8 m.In the first experiment a steel cylinder 1.8 m in diameter was driven into a soil to a depth of 3.6 m. Infiltrations of water and dye provided the means for direct observation of the effect of air entrapment upon the rates of infiltration as well as the primary pattern of water flow through the coarse subsoil. The rate of infiltration was observed to increase by nearly twofold when the entrapped air between the saturated surface layer and the shallow ground‐water table was vented directly to the atmosphere. Removal of the soil layers following infiltration of a dye solution showed that most of the infiltrating water moved through fingers ranging from 5 to 20 cm in diameter.In the second experiment, chloride distributions at six depths were measured following the application of a pulse of 0.3N CaCl2 solution to the soil surface. Chloride movement for the 20− to 60−cm soil depths averaged about 50% slower than that determined from the average pore‐water velocity at the soil surface. In contrast to this relatively low rate of chloride movement, several salt pulses reached the 120− and 180−cm depths soon after or before reaching the 60−cm depth. This greatly increased flow rate corresponds to the observations in the first experiment where flow became unstable and the solute moved in fingers of flow below the 60−cm depth.