bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Flooding on the Eh, pH, and Concentrations of Fe and Mn in Several Manitoba Soils
Authors: Olomu M. O. , Racz G. J. , Cho C. M. 
Published: July 2010

AbstractThe changes in Eh, pH, and concentrations of Fe and Mn in the solutions extracted from six Manitoba soils saturated with water were studied at various times of incubation at room temperature. Gradual reduction of the extracts was observed during the first 3 to 4 weeks of incubation. After this period, the extracts, in many instances, gradually returned to relatively oxidized states with occasional reduction. Somes changes in pH were observed but the magnitude of change was relatively small in soils with a relatively high cation exchange capacity. Both Fe and Mn concentrations generally increased with increased reduction. This trend was more pronounced for Mn than for Fe.E0 values calculated from experimentally measured Eh, pH, and concentrations of Mn appeared to indicate the presence of the Mn2O3 − Mn2+ redox system. The calculated values of E0 based on the assumption that the Fe2O3 − Fe2+ redox system was operative were far greater than the theoretical value.Almost all the Fe in soil solution was complexed with organic matter whereas Mn was either not complexed or only weakly complexed. The metal‐organic matter complexes were negatively charged. The soil solutions had a greater affinity for Fe than did 10‐4M EDTA. It is suggested that the very high degree of complexing of Fe in soil solution was most probably responsible for failure to obtain the theoretical E0 values for the Fe2O3 — Fe2+ redox system from the experimental data.
Factors Affecting the Coefficient of Linear Extensibility in Vertisols
Authors: Anderson J. U. , Fadul Kamal Elfadil , O'Connor G. A. 
Published: July 2010

AbstractThe relationship of the coefficient of linear extensibility (COLE) to other soil parameters was studied in 16 horizon samples from Ustert and Torrert profiles from the Sudan, Arizona, and New Mexico. The soil parameters studied were: percent of fine clay, coarse clay, silt, organic carbon, inorganic carbon, and EC × 103 and ESP. COLE was highly correlated with fine clay percentage and ESP, yielding a multiple correlation coefficient (R2) of 0.938. The R2 value for fine clay only was 0.868. X‐ray diffraction patterns indicate that the mineralogy of the fine clay ranges from dominantly well‐crystallized montmorillonite to poorly‐crystallized montmorillonite plus amorphous material. A predictive model which assumes that these Vertisols expand because of changes in basal spacings of fine clay, and that external expansion does not occur until voids are filled yields results which are highly correlated with measured COLE.
A Batch‐Handling Technique for Hot‐Water Extraction of Boron from Soils
Authors: John Matt K. 
Published: July 2010

AbstractA procedure was developed for the extrraction of boron by hot‐water. The method was suitable for a large number of samples and a high degree of accuracy was obtained. The proposed procedure was compared with the reflux and Gupta's modified methods by using three soils of varying texture and organic matter. The reproducibility of the proposed method was found to be superior to that of the others. The apparatus should improve the sample handling efficiency for a variety of extraction procedures that require hot solvents.
Solution Phosphorus Concentration and Growth of Rice (Oryza sativa L.) in Flooded Soils
Authors: Hossner L. R. , Freeouf J. A. , Folsom B. L. 
Published: July 2010

AbstractSoil solution P concentration was monitored at weekly intervals during the vegetative growth of Rice (Oryza sativa L. var. ‘Bluebelle’) on flooded soils from the gulf coast region of Texas. Significant increases in dry matter production were obtained from application of phosphate fertilizer. Average soil solution P concentration ranged from 0.02 to 5.28 ppm when all soils and P fertilization rates were considered. A linear relationship was obtained between the logarithm of the average soil solution P concentration and the P concentration or P uptake of the plant. Yields were greater than 90% of maximum when the average soil solution P concentration was greater than 0.1 ppm. The concentration of P in the plant tissue at 0.1 ppm soil solution P was 0.25%.
Effect of Soil, Cover, Slope, and Rainfall Factors on Soil and Phosphorus Movement Under Simulated Rainfall Conditions
Authors: Munn D. A. , McLean E. O. , Ramirez A. , Logan T. J. 
Published: July 2010

AbstractThree soils were treated with phosphorus at 25, 125, and 625 µg P/g soil in bare and cropped microplots and subjected to simulated rainfall. Five combinations of rainfall intensity and duration and microplot slope were used. Movement of soil and phosphorus from the microplots was measured. The quantity of runoff water, eroded solids, and P in the runoff increased with degree of slope and rainfall intensity. A high correlation (r = 0.997) was found between total P in the runoff from the bare plots and the quantity of soil eroded. Concentrations of soluble P in runoff from the plots was sufficient to eutrophy empounded water. The soil was nearly saturated with water and the system was “closed” so that runoff and leachate from a given rain were inversely related. Hence, the plant cover which was very effective in reducing runoff volume and soil erosion (as well as P losses) increased the quantity of percolating water. The increased percolation of water increased the P leached from cropped plots having uniformly mixed P. A well aggregated silty clay soil (Toledo) exhibited more infiltration than coarser textured soils with less granular structure.A modified Chang and Jackson fractionation of the sediments showed the dominant P fractions and their increases with rate of P application to be directly related to extractable Fe and Al content, pH, and percentage base saturation of the original soils. There was no significant change in the amount of P in organic form with rate of P application.While considerable caution must be used in extrapolating results of this kind to field conditions, the simulated rainfall and microplot method may prove useful in the study of nutrient movement by erosion and leaching under specified conditions.
Predicting Optimum Depth of Profile Modification by Deep Plowing for Improving Saline‐Sodic Soils
Authors: Rasmussen W. W. , McNeal B. L. 
Published: July 2010

AbstractA previously developed procedure for predicting the effect of mixed‐salt solutions on soil hydraulic conductivity (HC) was used to predict the relative hydraulic conductivity (RHC) of separate soil horizons from saline‐sodic soils, using a standard low‐salt solution following a standard high‐salt solution at a fixed exchangeable‐sodium level. These values were then used to predict the RHC of mixtures of the same horizons simulating profiles modified to various depths by deep plowing. Weighting RHC values for individual horizons by the depth fraction of each horizon in the soil mixture provided RHC values of proper magnitude, except when large proportions of calcareous subsolum material were incorporated into the mixture. Results were improved by multiplying calculated RHC values for each soil mixture by the initial HC of the mixture. This corrected for the filling of conducting pores in more permeable horizons by smaller particles from less permeable horizons during the mixing process (analogous to particle dispersion and pore sealing during the leaching of saline‐sodic soils). Soil constants determined for the mixed soils permit the prediction of the response of these soils to any other exchangeable sodium levels or soil solution concentrations of interest. Results were consistent with lysimeter and field plot observations on the same soils, including deep plowing trials.
Yield‐Nutrient Concentration Relationships in Slash and Loblolly Pine Seedlings
Authors: Terman G. L. , Bengtson G. W. 
Published: July 2010

AbstractRelationships between dry matter yields and concentrations of P and K were studied in slash pine (Pinus elliottii Engelm.) and loblolly pine (Pinus taeda L.) seedlings grown in greenhouse pot experiments comparing fertilizer rates and sources. The purpose was to determine if minimum and critical nutrient concentrations in pines could be determined more accurately in pot experiments than from field sampling or from very short‐term solution or sand culture studies.Growth of these species of pine seedlings for 6 to 12 months was found necessary to establish minimum plant P and K concentrations. Values which permitted continuing growth of slash and loblolly pines were about 0.07% P and 0.10% K, which were essentially the same in both the needles and the entire tops of 6‐ to 8‐month‐old seedlings. Concentrations of N, P, and Ca in seedlings for which growth was not limited by these nutrients were higher in needles than in the entire tops. Critical concentrations could not be established accurately from the results obtained.
Computer Procedure for Calculating Counter‐Diffusion Coefficients
Authors: Fuqua B. D. , Dunn J. E. , Brown D. A. 
Published: July 2010

AbstractA procedure for computer calculation of counter‐diffusion coefficients has been combined with the quick‐freeze technique to measure counter‐diffusion of ions. Two separate programs were employed to evaluate the counter‐diffusion coefficients at 0.1‐cm increments along the diffusion axis. Subroutines were available in the programs for plotting the ion distribution curve and the relationships of counter‐diffusion coefficients versus diffusion distance and counter‐diffusion coefficients versus relative concentration. Examples of Sr2+ diffusing against H+ and Na+ diffusing against H+ are presented to illustrate the potentialities for computer calculation and plotting of significant diffusion parameters. The diffusion coefficients of both Sr2+ and Na+ varied with changes in the ionic concentrations indicative of counter‐diffusion processes. The counter‐diffusion coefficients determined by the computer procedure were essentially the same as the values calculated by the graphical method. The computer procedure is an accurate and rapid method for calculating diffusion coefficients which are dependent on concentration and is adaptable to both single and multi‐ion systems.
Identification of Paleosols and the Fort Hall Geosol in Southeastern Idaho Loess Deposits
Authors: McDole Robert E. , Lewis Glenn C. , Fosberg Maynard A. 
Published: July 2010

AbstractInformation on the origin and history of the southeastern Idaho loess deposits was obtained through examination of 11 loess sections for evidence of paleosols. These sections comprised three transects traversing the loess deposits adjacent to the Snake River flood plain near Pocatello, Idaho. Characteristics identifying paleosols were found in 7 of the 11 sections. The paleosols were identified by zones in the loess section having one or more of the following properties: (i) a twofold increase in calcium carbonate equivalent, (ii) a sharp increase to a strong maximum in soluble salts, and (iii) an increase of 5 to 10% in the amount of clay. The paleosols show as strong or stronger development than the present modern soil.When a paleosol can be positively identified as occurring at more than one site, it becomes a marker used in the study of geologic formations such as loess deposits. A paleosol that serves this purpose is termed a geosol, and becomes a valuable tool in correlation of soil parent materials.The Fort Hall Geosol was identified in loess sections at 7 of the 11 study sites. The Fort Hall Geosol differed from the rest of the loess section and the other paleosols by having higher total clay content and finer clay, more montmorillonite, higher amounts of coarse silt, very fine sand and coarser sands (1.0 to 0.1 mm); and higher calcium carbonate and total salts.These identifying characteristics infer the nature of events which took place to form these paleosols. The characteristics suggest polypedogenesis. The initial event in the formation of the paleosols resulted in accumulations of relatively insoluble carbonates and clays. The Fort Hall Geosol represents a much stronger set of soil forming factors than those responsible for the formation of the existing modern soil or the other palesols in the section. Later, soluble salts accumulated in or above the zone of carbonate and clay accumulation. The soluble salts appear to be related to a subsequent deposition followed by a period of leaching.
The Problem of Assessing the Erosive Power of Rainfall from Meteorological Observations
Authors: Kinnell P. I. A. 
Published: July 2010

AbstractA number of rainfall parameters have been proposed in the past as bases for indexes of erosivity. Values for three such parameters—momentum, kinetic energy, and kinetic energy per unit horizontal area of the drop—were calculated from drop‐size data and relationships between rainfall intensity and the parameter values were developed. Examination of these relationships showed that both raintype and geographic location influenced the parameter values. This suggests that the detachment ability of rainfall, at a given rainfall intensity, may vary between raintypes and geographic locations. However, the degree and direction of the influence depended on which parameter was being considered. The ordering of five raintypes at Miami, Florida, determined by values obtained at given rainfall intensity from the intensity‐parameter regressions for momentum and kinetic energy was reversed for kinetic energy per unit horizontal area of the drop. Therefore, in the absence of data on the rate of soil detachment, it is not possible at present to classify the raintypes at a geographic location according to their detachment power. In the view that runoff is a major factor in controlling the transport phase of soil erosion, the observations indicate that rainfall parameters may only be evaluated as indexes of the detachment power of rainfall if they are determined directly and simultaneously with soil loss, and provided that the influence of runoff on soil loss is taken into account.
Simultaneous Extraction of Hydroxyatrazine, Atrazine, and Ametryne from Some Hawaiian Soils
Authors: Goswami Kishore P. , Green Richard E. 
Published: July 2010

AbstractA simple procedure is described for simultaneous extraction from soil of 2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine (atrazine), 2‐methylthio‐4‐ethylamino‐6‐isopropylamino‐s‐triazine (ametryne) and their common hydrolysate (hydroxyatrazine = HA). The procedure involves extraction by shaking in acidified methanol, centrifugation, and subsequent quantitative separation of HA from the parent triazines by liquid‐liquid partitioning. The pH of methanol was adjusted with 4N HCl to obtain a final pH of 2.5 in the soil extract, using a 1:10 soil/solvent ratio. HA recovery with one extraction was 94% for both Molokai (Typic Torrox) and Hilo (Hydrandept) soils having soil extract pH values of 2.4 and 3.4, respectively. In all cases atrazine and ametryne were quantitatively recovered in soil extracts. After protonation HA was quantitatively separated from the mixture of HA and atrazine or ametryne by partitioning in an aqueous methanolic soil‐extract/chloroform system when the water/methanol extract ratio was 1.25. HA extraction from soil was extremely pH dependent. Dissolution of calcium chloride in acidified methanol decreased recovery of added HA from 94% to 76% for Hilo soil but had no effect on % HA recovery from Molokai soil; the electrolyte was found to increase the pH of Hilo soil extract, a result of the net positive charge of this soil at low pH. The recovery of added HA from Ca‐montmorillonite was 33%, suggesting that the procedure may be less suitable for soils with high permanent negative charge.
Genesis, Morphology, and Classification of Mounded Soils in Eastern Oklahoma
Authors: Allgood F. P. , Gray Fenton 
Published: July 2010

AbstractNumerous small mounds are unique features of landscapes that extend from the southern part of Missouri to the coast of Texas. Many hectares of eastern Oklahoma are included in this vast area. The mounds occur in densities of 8 to 16/ha.These mounds were studied with special emphasis on the genesis, morphology, and classification of associated soil pedons. Laboratory measurements included particle size distributions, bulk density, extractable cations, and organic matter extractions.Soil morphological features and laboratory analyses indicated that the development of the mounded soils differs from that of the associated intermound pedons by being highly altered by the many organisms of the landscape that assemble in the selected elevated soil to escape seasonal wet soil conditions.Mounded soils of Site I are classified as Aquic Paleudolls or Aquic Argiudolls in the present system of soil classification (12). But most of the mounded soils which were studied would be better classified with a vermic modifier.
Effective Available Water and Its Relation to Evapotranspiration Rate, Depth of Wetting, and Soil Texture
Authors: Miller D. E. , Aarstad J. S. 
Published: July 2010

AbstractThe effect of evapotranspiration (Et) rate on effective available water (EAW) was evaluated for three soils ranging in texture from sand to silt loam, at evapotranspiration rates of about 0.4 to 1.3 cm per day, and at two depths of wetting. In all cases, as evapotranspiration rate increased, drainage following irrigation decreased and as a result EAW increased. The increase in EAW due to Et rate was relatively greater in the sand than in the finer textured soils. If only midsummer Et rates are considered, EAW is estimated quite well from a usual field capacity test, provided soil depth and soil texture are considered in determining the sampling time for characterizing field capacity. If one considers usable water referenced to some safe depletion level rather than available water referenced to the 15‐bar percentage, the effect of Et is more important. EAW is influenced differently by depth of wetting in different textured soils.
The Water‐Ice Phase Composition of Clay‐Water Systems: I. The Kaolinite‐Water System
Authors: Anderson Duwayne M. , Tice Allen R. , Banin Amos 
Published: July 2010

AbstractPrevious work has indicated that when water‐ice phase composition curves are normalized to unit surface area, unfrozen water content values at all temperatures are higher for the kaolinite‐water system than for other clay‐water systems. In addition, the water‐ice phase composition curve for this system appeared to be the resultant of the superposition of two power curves of the form Wu = αθβ. The measurements have been repeated using an improved isothermal calorimeter and the earlier results confirmed. Values of Wu per unit surface area for the kaolinite‐water systems are more than twice as large as those for the montmorillonite‐water systems. Addition of polyox (polyethylene oxide) to the kaolinite‐water system had little effect on Wu in the range of 0 < θ < 1.7 but diminished Wu significantly at values of θ > 1.7. The observations are explained qualitatively in terms of a domain model of clayimbibed water.
Sorption of Nitrogen Dioxide by Calcareous Soils
Authors: Prather Robert J. , Miyamoto Seiichi , Bohn Hinrich L. 
Published: July 2010

AbstractThe NO2 sorption capacity and rate of calcareous soils, a calcic soil, and a granular limestone were measured at room temperature by passing air or nitrogen gas containing NO2 through them. In dry air (humidity < 5%), NO2 sorption reached an equilibrium value within 2.5 min. In moist air (humidity > 95%), NO2 sorption increased to as much as 10‐fold that in dry air and approximately equaled the acid‐titratable basicity of calcareous soils. The sorption rate was proportional to the unreacted fraction of the capacity with sorption rate constants ranging from 0.015 to 0.03 min‐1 at a NO2 concentration of 0.5% volume. At a concentration of 0.1%, the sorption rate was slower but the capacity remained unchanged. Sorption of NO2 was similar when either air or a nitrogen carrier was used.
Variation of 15N in Corn and Soil Following Application of Fertilizer Nitrogen
Authors: Kohl D. H. , Shearer G. B. , Commoner B. 
Published: July 2010

AbstractSamples of corn (Zea mays L.) plant tissue (grain and leaf) were obtained from the University of Illinois South Farm plots and from the University of Illinois Morrow plots. Soil samples were also obtained from each of the South Farm plots. The 15N:14N ratio of the nitrogen in these corn plants is shown to be sensitive to the source of nitrogen taken up by the plants. A systematic decline in δ15N (per mill excess 15N) was observed within a narrow range of variation (about 4 δ15N units) with increasing applications of commercial nitrogen fertilizer. This result is consistent with increasing contributions of fertilizer nitrogen to the plant, as the fertilizer had a δ15N value close to zero. Similarly, the influence of a small amount of manure nitrogen (40 kg nitrogen/ha) applied over many years was detected in samples grown on the University of Illinois' historic Morrow plots. The results indicate that the nitrogen of grain and the leaf tissue of young plants is derived at least in part from different pools reflecting different proportions of fertilizer and soil nitrogen or fertilizer nitrogen of different δ15N, due to the time course of its fractionation. Unexplained differences between the influence of soybeans and clover on δ15N were also observed. Neither the quantity nor the δ15N of the total nitrogen was influenced by short term (3 years) addition of large quantities of nitrogen (448 kg/ha) to the soil on the South Farm plots.A relatively high value of δ15N was obtained for NO3‐ in the soil profile in the fall following spring application of 448 kg nitrogen/ha. This suggests that the observed nitrate nitrogen was not derived from nitrogen molecules applied as fertilizer in the spring, but originated rather from the exchange of fertilizer nitrogen for soil nitrogen and/or the “priming effect” (release of extra soil nitrogen as a result of the application of fertilizer nitrogen).
Thermodynamics of Ion Exchange
Authors: Ravina Israela , DeBock Joseph 
Published: July 2010

AbstractThe local formulation of nonequilibrium thermodynamics is used to define the electrochemical potentials in the ion‐clay‐water system, thus enabling development of an improved nonempirical approach to cation‐exchange processes. The presence of the electrical field in the system is expressed by a proportional increase of the pressure in the double layer. The effect of the electrical field on the chemical potentials of the exchangeable cations is divided into the common electrostatic term and a term dependent on their polarizabilities. For systems containing a mixture of monovalent ions it can be assumed that the electrostatic effect of the electrical field is the same for each of the exchangeable cations. Using values of the polarizabilities and intrinsic volumes of the alkali metal cations, the free energies of exchange with sodium in montmorillonite were calculated. The calculated free energies were found to be in good agreement with experimental values.
Survival of Two Strains of Rhizobium in Soil
Authors: Danso S. K. A. , Alexander M. 
Published: July 2010

AbstractA sensitive method was devised for determining the abundance of strains of Rhizobium meliloti and R. trifolii introduced into soil. This method relies on the use of streptomycin‐resistant mutants which, after inoculation into soil, are counted on a medium supplemented with streptomycin at concentrations sufficient to inhibit most soil microorganisms.Viability of streptomycin‐resistant strains of R. meliloti and R. trifolii did not fall markedly when the bacteria were introduced into moist soils. Various organic matter amendments did not significantly alter the decline rate of the rhizobia. R. meliloti populations did not lose viability readily in moist sand, in desiccated soils, or in solutions free of organic nutrients, but the population density fell rapidly when the bacteria were inoculated into desiccated sand. The rate of decline in cell number was enhanced with increasing temperature. Both rhizobia survived well in dry, nonsterile soil.