bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Adsorption by Dry Soil and Its Thermodynamic Functions
Authors: Cary J. W. , Kohl R. A. , Taylor S. A. 
Published: July 2010

AbstractThe adsorption of increments of water vapor on Millville loam soil was studied in an air‐free system. The resulting data included the amount of water that would condense on the soil at different relative humidities up to 90% at 14.8°, 24.8°, and 34.8°C. The temperature rise of the samples during adsorption was also recorded and the heat liberated during the reaction was calculated. Both integral and differential thermodynamic values were computed. A critical evaluation of the entropy function showed the integral values to be more useful than the differential values so far as describing the physical state of the system was concerned. In general, calculations of thermodynamic quantities based on the temperature dependence of the systems proved to be unreliable at low relative humidities due to changes in the available surface.Specific conclusions drawn from the data suggest that when equilibrium relative humidity is < 80% in an air‐free Millville loam system, the average entropy of the adsorbed film is a little greater than that of corresponding liquid water, but the average internal energy of the film is always less than that of liquid water, even though the heat content may become slightly greater as the relative humidity rises above 70%.
Viscoelastic Functions for Soil
Authors: Waldron Lawrence J. 
Published: July 2010

AbstractBriquets of Yolo silt loam have previously been shown to be viscoelastic. Three viscoelastic functions which describe the stress, strain, and time relations for two types of loading were obtained when the soil was in equilibrium with humidities ranging from 15 to 90% at 70°F. These functions were the shear creep compliance, the distribution of retardation times, and the complex shear compliance. The functions were very sensitive to small changes in water content. Equal‐time shear creep compliances were exponential functions of water content. Increasing temperature from 40° to 100°F apparently did not change the rates of the deformation process uniformly since temperature coefficients of equal‐time compliances reversed sign as the stress duration passed from 1 to 7,200 seconds. The functions are discussed in terms of a two‐phase concept.
Reactions of Phosphate with Soluble and Exchangeable Nickel
Authors: Pratt P. F. , Bair F. L. , McLean G. W. 
Published: July 2010

AbstractWhen solutions of NiCl2 and KH2PO4 were titrated with NaOH, the immediate reaction product was an amorphous precipitate having a composition corresponding to 6NiHPO4 · Ni(OH)2 · 7H2O or 4NiHPO4 · Ni3(PO4)2 · 9H2O. At all pH values < 7, the precipitate was free of Ni(OH)2 or had a constant Ni(OH)2 content, but at pH values > 7, the Ni(OH)2 increased with increase in pH. When the amorphous precipitate was incubated at 25°C., crystalline products began to appear at 4 weeks and at 12 weeks the crystallization appeared to be complete. The main crystalline product was Ni3(PO4)2 · 8H2O. Crystallization was accompanied by acidification and also by a large reduction in the solubility of Ni. In the pH range of 6.5 to 7 the solubility of Ni was reduced to about 2 ppm.Nickel‐saturated clays treated with phosphate showed the same reactions as found in solution. The exchangeable Ni was reduced to about 3% saturation.
Penetration of Wax Layers by Cotton Roots as Affected by Some Soil Physical Conditions
Authors: Gardner H. R. , Danielson R. E. 
Published: July 2010

AbstractThe use of a wax layer for root penetration tests under controlled soil conditions has made it possible to separate from other factors in the soil the effect of mechanical impedance on the growth of plant roots. The penetration percentage of cotton roots increased as soil moisture tension was increased from 0.05 bar to 0.52 bar then decreased as tension was further increased to 10.8 bars. The penetration also decreased with increasing salt content in the soil solution. Decreased aeration as measured by CO2 content also lowered the penetrating ability of cotton roots. An increase in bulk density of the soil from 1.0 g. per cc. to 1.4 g. per cc. did not affect the penetrating ability of cotton roots into the wax layer.
Investigations Concerning Nitrogen Loss Through Chemical Reactions Involving Urea and Nitrite
Authors: Sabbe Wayne E. , Reed Lester W. 
Published: July 2010

AbstractThe urea‐nitrite Van Slyke reaction was studied to determine the conditions necessary for this reaction to contribute to evolution of nitrogen gas (N2) by chemical denitrification in soils. The reaction was carried out in buffer solutions and the evolution of gases was analyzed quantitatively. The variables studied were pH, acidity, time, and reactant concentrations. Two conditions necessary for N2 evolution under an anaerobic atmosphere from an urea‐nitrite solution are (1) pH 6.0 or lower, and (2) a concentration of each reactant of 0.05 mg. N per ml, or greater. Evolution of N2 increased with decreasing pH and increasing reactant concentration. Nitric oxide (NO) formation was increased by increasing acidity, increasing nitrite concentration, and decreasing urea concentration. Nitrite accumulation in soils following urea fertilization requires an alkaline media. Therefore, the possibility that this pathway (urea‐nitrite reactions) of nitrogen loss occurs in soils is doubtful.
Ammonia Sorption and Retention by Plant Residue Materials
Authors: Coffee R. Clifford , Bartholomew W. V. 
Published: July 2010

AbstractInvestigations were conducted to measure the quantities of NH3 physically sorbed and the quantities of sorbed NH3 retained against evacuation by some common plant residues when exposed to NH3 in a dry condition and with different amounts of moisture. With increases in NH3 pressure both moist and dry samples of each plant residue physically sorbed increasing quantities of NH3. When saturated with NH3, evacuated, and then saturated a second time each dry plant material sorbed less NH3 during the second than during the first saturation. Increases in moisture content resulted in increases in physical sorption of NH3 across the entire range of partial pressures of NH3 employed. Saturation of the moist plant residue samples with NH3 resulted in some measurable increases in NH3 content after evacuation.
A Study of Isotopic Dilution as a Method for Relating Phosphorus Retention to Availability of Phosphorus in Widely Different Soils
Authors: Baker Dale E. 
Published: July 2010

AbstractSix soils which were considered different with respect to release and retention of P were limed and allowed to equilibrate with a constant amount of P32 and 25, 100, and 400 ppm. of P31 by alternate wetting and drying 4 times prior to seeding Turghi millet and Tokyo buckwheat. The objective was to relate P retention characteristics to “availability of P” in different soils. “Active solid phase P” as determined by isotopic dilution was found to be an index of the amount of “available P” contained in a soil. A constant proportion of the active solid phase P was not in solution or removed from all soils by any of the extracting reagents. The percent active solid phase P removed by all extractants was affected by the rates of added P. From the results it was concluded that the percent active solid phase P removed by Bray's No. 1 extractant from each soil type was an index of its retention characteristics, if the native active solid phase P was in equilibrium with the added P32.
The Effect of Discrete Ped Density on Corn Root Penetration in a Planosol
Authors: Edwards W. M. , Fehrenbacher J. B. , Vavra J. P. 
Published: July 2010

AbstractCorn root penetration studies in an Illinois Planosol, Weir silt loam, indicate that large corn roots are confined to the larger spaces between peds but that many medium and small roots penetrate about one‐half of the total discrete peds in the claypan B horizon directly under a corn hill. It appears that a discrete ped bulk density of about 1.80 g. per cc. is the threshold density above which peds are not penetrated by roots in this soil. The minimum intraped (within ped) porosity of peds penetrated by roots was about 33%. Mixing of the A and B horizons reduced the root restrictive effect of the A2 horizon.
Approximating Soil‐Moisture Storage in Experimental Watersheds by Means of Precipitation and Streamflow Records
Authors: Reinhart K. G. 
Published: July 2010

AbstractAn estimate of total soil‐moisture storage capacity of an experimental watershed is needed to understand its hydrology. A reliable estimate may be very difficult to obtain, particularly in a forested watershed, because of variations in and difficulties of measuring soil depth, root depth, texture, bulk density, stone content, and moisture content. A method is suggested for approximating storage from precipitation and streamflow records. Precipitation minus runoff—in selected periods when ample precipitation follows a dry spell—provides the estimate of soil‐moisture storage capacity. The method is illustrated with data from the Fernow Experimental Forest in West Virginia and is applied to two other watersheds in the Northeast. Limitations of the method are also discussed.
Relation Between Soil Aeration and Ethyl Alcohol Accumulation in Xylem Exudate of Tomatoes
Authors: Fulton J. M. , Erickson A. E. 
Published: July 2010

AbstractExperiments were designed to measure the influence of soil oxygen stress and other environmental variables on the accumulation of ethanol in tomato plants. Oxygen stress was imposed by varying the soil moisture tension over a narrow range of low values. Ethanol was observed in the exudate samples when the rate of oxygen diffusion through the soil solution fell below 38 × 10‐8 g.cm.‐2min.‐1. A small reduction in oxygen supply below this value was associated with a large increase in ethanol. In cases of severe oxygen stress the physiological concentration of ethanol was sufficient to be toxic. Plants bearing flowers accumulated more ethanol than younger ones and those subjected to oxygen stress in bright light accumulated more ethanol than those in the dark.
Ion Diffusion: I. A Quick‐Freeze Method for the Measurement of Ion Diffusion in Soil and Clay Systems
Authors: Brown D. A. , Fulton B. E. , Phillips R. E. 
Published: July 2010

AbstractThe method combines a radioisotope‐tracer technique for measuring ion distribution by quick‐freezing the exchange medium and sectioning it into 50µ segments with a refrigerated microtome. Ten‐50µ sections were placed in separate counting pans for a quantitative radiation assay. From these data the distribution resulting from ion diffusion in montmorillonite and kaolinite clays and Sharkey and Dundee soils was obtained.The accuracy of the freezing and sectioning method was determined by using replicate‐radioactive cores in which ion diffusion had not occurred. These cores were sectioned, counted for radiation, and then weighed. The coefficient of variation for the weight of clay or soil sections was 1.89, 2.14, 2.27, and 3.70% for kaolinite, montmorillonite, Dundee silt loam, and Sharkey clay, respectively. Coefficients of variation in the activity of the sections of exchange media were 2.39, 2.80, 3.18, and 1.29%, respectively. The coefficient of variation in the apparent diffusion coefficient for Rb86 in replicated cores of kaolinite clay was 6%.
Fragipan Soils: Morphological Relationships
Authors: Bailey H. H. 
Published: July 2010

AbstractField descriptions and certain laboratory data for 17 soil profiles representing Bedford, Calloway, Dickson, Grenada, Henry, Mercer, and Tilsit series in Kentucky were obtained. All of the soils contain fragipan horizons. Each genetic horizon of each profile was characterized by morphological description, including pH. Greatest thickness of pan development occurred in the poorly and somewhat poorly drained loessial soils; moderately welldrained soils developed in limestone residum with loess additions was second in thickness of pan development; well‐to‐moderately well‐drained sites from loess‐free limestone residium was third; moderately well drained mixed sandstone, shale, and siltstone residuum fourth; and moderately well‐drained deep loess least. The poorer the drainage the greater the pan development in deep loess. Colors in the pan horizons tended to differ from those above by having more yellowish hues and depressed chroma. Pan horizons generally contained more clay and correspondingly less silt than the horizon above the pan. Pans were generally more acid, ranging around pH 5, than horizons above or below. Pans tend to reversibly lose their characteristic consistency under wet conditions.
Fragipan Soils: Certain Genetic Implications
Authors: Hutcheson T. B. , Bailey H. H. 
Published: July 2010

AbstractThis study of a number of fragipan soils derived from a wide range of parent materials was undertaken to test an hypothesis concerning fragipan formation which had as its foundation data obtained from loessial soils. Particle size distributions and selected chemical properties were determined and comparisons of the data for the Bx and adjacent horizons were made. The portion of the original hypothesis suggesting that fragipan soils were severely leached prior to pan formation and that pan formation resulted from tight packing of dispersed clay particles is acceptable with certain limitations. On the other hand, it cannot be accepted that Ca:Mg or Ca:Mg + Na ratios are factors of general importance in fragipan formation.
Grass Opal in Some Chestnut and Forested Soils in North Central Oregon
Authors: Witty John E. , Knox Ellis G. 
Published: July 2010

AbstractThe practicability of using grass opal as an indicator of the vegetative history of soils was investigated in a forest‐grassland transition. Opal phytoliths isolated from grass and other plants were used as standards in the identification of grass opal from soils. Soil horizon samples were selected from 12 locations. Grass opal content was calculated from grain counts of the 15 to 100µ fraction.The content was about 10 times greater in grassland soils than in forest soils. This indicates that the vegetative boundary has been generally stable throughout the time period required for accumulation of the grass opal, estimated to be about 4,000 to 7,000 years. Some change of vegetation was indicated at only two sites. Study of grass opal may be expected to yield much information about the vegetative history of soils.
A Steady‐State Method for Laboratory Measurement of the Oxygen Diffusivity of Porous Materials
Authors: Willey C. R. , Tanner C. B. 
Published: July 2010

AbstractA steady‐state system using a large membrane‐covered electrode as a quantitative oxygen reducing sink and small membrane‐covered electrodes to measure oxygen concentrations was devised for measuring the oxygen diffusion coefficient D of soil or other porous material artificially packed in a sample‐holding tube. With this system, D was measured both with a zero net nitrogen flux through the sample in a close‐end system and with the counter‐current molar fluxes of oxygen and nitrogen made equal by injecting nitrogen into the system. For 100µ and 300µ diameter glass beads these methods gave values of D that agreed within 3% and were within 8% of values of D measured with a transient method for the same samples. Diffusion coefficients determined for air were in the range of those reported in literature.
Strength and Bulk Density of Compacted Mixtures of Kaolinite and Glass Beads
Authors: Lotspeich Frederick B. 
Published: July 2010

AbstractCompacted mixtures of kaolinite and glass beads were used to test a hypothesis that the number of contact points of a matrix influences its strength. Four glass bead mixtures were used: (1) a single‐sized bead, (2) 2 sizes of beads designed to permit cubic, but not tetrahedral, packing of the largest size beads, (3) 2 sizes of beads designed to permit tetrahedral packing of the largest sized beads, and (4) 4 sizes of beads designed to permit tetrahedral packing. From 2 to 40% clay was added to each glass bead mixture; moisture tension at time of compaction ranged from 1/3 to 15 bars.The 4‐component mixture with clay contents above 25% gave the highest dry strength. Maximum bulk densities in all glass bead mixtures were attained at clay contents of 20 to 30%. Maximum strength and bulk density for each mixture was attained at a moisture content between 1 and 5 bars tension regardless of clay content.
Effect of Carbon Dioxide on Cotton Seedling Root Penetration of Compacted Soil Cores
Authors: Tackett J. L. , Pearson R. W. 
Published: July 2010

AbstractThe level of CO2 and of subsoil density were varied in a growth chamber study of the interaction of these two factors on root growth of cotton seedlings at constant O2 concentration. At very low density root elongation rate decreased progressively with increasing CO2, although moderate to good growth occurred even at 24% CO2, the highest concentration used. At higher subsoil level densities, CO2 had little effect on root penetration. Retardation by CO2 was somewhat more severe for roots growing into solution culture than for those growing into loose subsoil, indicating that application of results of aeration experiments in nutrient solution to soils should be made with caution. Results suggest that in well‐drained, medium‐to‐coarse‐textured soils such as the Norfolk, CO2 will seldom be a limiting factor for root growth even in compacted zones near the surface. The mechanical impedance of such zones, will definitely restrict root penetration and proliferation in subsoils.
The Relationship between pH and Ammonia Equilibria in Soil
Authors: du Plessis M. C. F. , Kroontje Wybe 
Published: July 2010

AbstractInvestigation of the relationship between pH and NH3 equilibria in soils revealed that an increase in the concentration of NH4+, applied as (NH4)2 SO4, stimulated NH3 losses from fine‐textured soils at pH's ranging from 4.5 to 7.1. Ammonia volatilization was directly related to the initial pH of the soil and increased with an increase in pH. It was postulated that NH3 may be volatilized, even from acid soils, due to the equilibrium NH4+ + OH‐ ⇄ NH3 + H2O. By using initial concentrations of NH4+ from (NH4)2 SO4 applied, initial pH of an aqueous suspension of the soil and a value Kb = 1.80 × 10‐5, values of NH3 losses were predicted. The linear relationship found between predicted and measured amounts of NH3 losses from acid as well as neutral soils, was interpreted as evidence of the existence of the proposed volatilization mechanism in soils.
Changes in Exchangeable Potassium Observed on Drying Soils after Treatment with Organic Compounds: I. Release
Authors: Bates T. E. , Scott A. D. 
Published: July 2010

AbstractWhen Marshall subsoil samples were dried in an oven at 110°C. for 48 hours, the NH4OAc extractable K increased from 27 to 210 ppm. This release of K was reduced to varying degrees by adding a wide variety of organic compounds to the soil samples before they were dried. The effect of these additives was not related to their solubility in water, dielectric constant or dipole moment. On the other hand, compounds with a high molecular weight and high boiling point were particularly effective in preventing K release.All alcohols tested reduced K release. Their effect increased with the amount added and their boiling point. Thus, the effect of normal primary alcohols increased with chain length and the effect of butyl alcohols decreased with chain branching. K release was eliminated by adding normal alcohol with a molecular weight equal to or greater than butanol.Glycerol, dextrose, sucrose, and n‐octanol additions were particularly effective in preventing K release. The relative effect of these additives was related to the volume of each added, not the number of moles or hydroxyl groups involved. The addition of less than 2 ml. of these compounds per 10 g. soil eliminated K release entirely.
Chemical and Mineralogical Studies on Slick Spot Soils in Idaho
Authors: Lewis G. C. , White J. L. 
Published: July 2010

AbstractA study of a slick spot and associated soils showed the slick spot soil to be characterized by high salts and exchangeable Na throughout the profile whereas the high concentration of salts and exchangeable Na occurred at progressively greater depths in the profile in proceeding from the slick spot into the adjacent associated soils.They clay‐size minerals found in both the slick spot soils and the associated soils were illite, montmorillonite, kaolinite, quartz and feldspars. Montmorillonite maxima occurred at progressively lower depths in the profile in proceeding from the slick spot into the associated soils.Partial dissolution studies on the clay‐size fraction of the soils showed large amounts of amorphous material with the greatest amount being present in the slick spot soil. It was postulated that this amorphous material together with the high Na content contributed to the impermeability of these soils.
Significance of Biological Sulfate Reduction in Soil Salinity
Authors: Ogata G. , Bower C. A. 
Published: July 2010

AbstractThe effect of native and applied organic matter (straw) on sulfate reduction under anaerobic conditions in arid‐zone soils was studied in the laboratory. Changes in the composition of dissolved and adsorbed ions as a consequence of SO4 reduction was also studied. The results indicate that SO4‐reducing microorganisms are generally present in arid‐zone soils. Appreciable reduction of any SO4 present does not occur when arid‐zone soils become anaerobic by waterlogging, however, unless undecomposed organic matter (plant residue) is present or the soil organic matter content is high (e.g., > 5%). Sulfate reduction results in the formation of equivalent amounts of carbonates which, upon reaction with soluble or exchangeable Ca and precipitation as CaCO3, cause decreases in soil salinity and increases in the exchangeable sodium percentage.
Mica Surface Morphology Changes During Weathering
Authors: Raman K. V. , Jackson M. L. 
Published: July 2010

AbstractElectron microscopic observations of mica surfaces by the carbon replica technique indicate that weathering, a major process of K release in soils, proceeds at the (hkO) fracture edges and at the crystallographic dislocations distributed on the (001) cleavage faces of mica crystals. Fresh cleavage surfaces of a paragonite with muscovite inclusions show discontinuity of the layers and marginal rolling at edges of K mica cores 3 to 5µ in diameter. A closely intergrown mosaic of the two micas is indicated rather than a true solid solution of the K,Na. Much of the interlayer Na in paragonite readily exchanges for K on treatment with 1N KCl solution and the surface assumes the smoother morphological features of K mica. Fresh cleavages of muscovite and margarite show some folding and scrolling of layers at dislocation edges. Artificial laboratory weathering of biotite to vermiculite by treatment with MgCl2 produces surface morphology similar to that of natural vermiculites. Removal of K from biotite with tetraphenylboron causes the surfaces to crack open, yielding fresh (hkO) fracture edges. Weathering with NaOH or HCl produces characteristic surface changes. Treatment of biotite with HF for one minute produces humps scattered at 0.1 to 1µ intervals over the (001) cleavage surfaces. Desilication for a longer period produces characteristic etch pits and corroded surfaces with serrated edges.These surface studies provide a new model of mica weathering at (hkO) edges formed on the (001) cleavages, and shows layer flexibility on cation exchange which greatly aids in explanation of K release and fixation in soils.