bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Solution Composition on Soil Hydraulic Conductivity
Authors: McNeal B. L. , Coleman N. T. 
Published: July 2010

AbstractDecreases in hydraulic conductivity with decreasing electrolyte concentration and increasing sodium adsorption ratio (SAR) of the percolating solution were assessed for seven soils of varying clay mineralogy. The decreases were particularly pronounced for soils high in 2:1 layer‐silicates, with the most labile hydraulic conductivities being exhibited by those soils containing the most montmorillonite. A soil containing considerable amorphous material was much more stable then the average, and a soil high in kaolinite and sesquioxides was virtually insensitive to variations in solution composition. No property of the solution alone was sufficient to characterize the response of the soils to a given solution, though expression of results in terms of the exchangeable sodium percentage (ESP) of the soil and the total salt concentration of the ambient solution produced more nearly similar curves for soils of similar clay mineralogy. The soils commonly demonstrated rather pronounced hydraulic conductivity decreases in the ESP range of 20 to 35 at salt concentrations of 3 to 50 meq/liter. The decreases were largely irreversible upon the reapplication of high salt or high Ca solutions to the soil, except for those soils containing greater than 10% montmorillonite on a whole‐soil basis.
Effect of Solution Composition on the Swelling of Extracted Soil Clays
Authors: McNeal B. L. , Norvell W. A. , Coleman N. T. 
Published: July 2010

AbstractFor soils containing expansible minerals, the swelling of extracted soil clays in mixed NaCl‐CaCl2 solutions was well correlated with relative hydraulic conductivity of the soils to the same solutions, and with theoretical interlayer swelling values based on a “domain” model. In this model, mixed Na‐Ca clays were considered to consist of discrete Na‐ and Ca‐regions, with only the Na‐regions swelling at low salt concentrations. The correlations suggest that the most plausible mechanism for hydraulic conductivity decreases in soils containing significant amounts of expansible minerals is the closing of conducting pores by insitu mineral swelling. However, a dispersion process activated by the interlayer swelling of expansible minerals would also be compatible with the data.
Reactions of Surfactants with Montmorillonite: Adsorption Mechanisms
Authors: Law J. P. , Kunze G. W. 
Published: July 2010

AbstractFour clays were treated with each of eight surfactants at three treatment rates. Volclay and the clay fraction from two montmorillonitic soils were treated with 100, 50, and 10 mmol /100 g.; and kaolinite was treated with 10, 5, and 1 mmol /100g.Adsorption was measured quantitatively by the thermogravimetric method. Adsorption mechanisms were investigated by X‐ray diffraction and differential thermal analysis.The surfactants included three anionic, three cationic, and two nonionic compounds. The anionics were not adsorbed in appreciable quantities and anion exchange of kaolinite appeared to be equal to or somewhat greater than that of montmorillonite. Anionics had no effect on the d‐spacing of montmorillonite and did not interfere with hydration of clay surfaces.Cationics were strongly adsorbed by the clay surfaces through ionic bonding in amounts equal to or even greater than the cation‐exchange capacities of the clays. The excess material was probably held by van der Waals forces between the alkyl radicals which increased with chain length. Their presence on clays significantly reduced hydration and water content to the extent of making the clay surfaces completely hydrophobic at the high treatment rates.Nonionics were adsorbed by hydrogen bonding of polar‐active groups to oxygen‐rich clay surfaces. Their sorption energies were somewhat greater than that of water, and they displaced water when adsorbed. Both cationic and nonionic compounds were held in the interlayer spaces of montmorillonite and tended to form double layers if sufficient material was present.
Reactions of Surfactants with Montmorillonitic Soils
Authors: Law J. P. , Bloodworth M. E. , Runkles J. R. 
Published: July 2010

AbstractTwo montmorillonitic soils were treated with each of eight surfactants at three treatment rates: 1%, 0.1%, and 0.01% by weight. The effects of the treatments on certain important physical properties of the soils were investigated by means of aggregate stability analysis, capillary rise measurements, and modulus of rupture.The surfactants included three anionic, three cationic, and two nonionic compounds. The anionics were not strongly adsorbed by the soils. When the soils were dried in contact with them, they were weakly held and readily released to the liquid phase upon rewetting. Their effects on soil physical properties were directly related to the lowering of surface tension of the liquid phase, and the magnitude of the effect was strongly dependent on treatment rate.The cationics were strongly adsorbed by the soil exchange complex and not readily released upon rewetting. Their effects on soil physical properties were directly related to the degree of hydrophobicity imparted, which increased with alkyl chain length and amount of material added to the soil.The nonionics were adsorbed by hydrogen‐bonding to clay and other oxygen‐rich mineral surfaces. Their sorption energy was somewhat greater than that of water, and they displaced water from the surfaces. Their effects on soil physical properties were small and in proportion to the amount of chemical added. Those effects were related to reduced hydration of surfaces and the hydrophilic centers associated with the nonionic compounds.
Nitrification by Heterotrophic Soil Microorganisms
Authors: Doxtader K. G. , Alexander M. 
Published: July 2010

AbstractHeterotrophic soil bacteria, actinomycetes, and fungi produced nitrite when grown in media containing various reduced forms of nitrogen. Amines, amides, N‐alkylhydroxylamines, oximes, hydroxamic acids, and aromatic nitro compounds served as substrates for nitrite formation by individual microorganisms. The yield of nitrite varied with the organism and the substrate, ranging from 190 ppm of nitrite‐nitrogen with acetaldoxime as a nitrogen source to a few ppm with certain substituted ureas. None of the microorganisms formed nitrate from the substrates tested. One isolate, identified as a species of Fusarium, converted more than 90% of the nitrogen of pyruvic oxime to nitrite. Cell extracts of the fungus catalyzed the production of nitrite from the oxime.
Phosphorus Status of Horizons of Four Benchmark Loessial Soils of the Central Great Plains Region
Authors: Black A. L. , Whitney R. S. 
Published: July 2010

AbstractGenetic horizons of the Colby, Weld, Rago, and Keith loessial soil series were investigated. Buried soils occurred in the Rago and Keith series. Each horizon was subjected to various chemical analyses and used in greenhouse fertilizer studies.Marked differences in P content and availability to plants occurred among horizons and with profile depth. Yields and plant uptake of N and P from nonphosphated horizons were positively correlated with the initial NaHCO3‐soluble P in the soils when N was uniformly applied. By adding 8.8 or 35.2 ppm P per pot, yields were similar within a given horizon, but differed markedly among horizons of the same profile. With adequate N added, spring barley (Hordeum vulgare L. ‘Moravian’) yields from the Rago A‐B subsoil horizon and the Rago Ap surface soil were similar, but the Weld B3ca subsoil horizon yielded 50% more than the Weld Al surface soil. All other subsoil horizons were deficient in available P, and maximum yields occurred only when both N and P were added. Fertilized subsoils producing more dry matter yield than their respective surface soils were: Colby AC, Cca, and C; Weld B3ca, Cca, and C; and the Rago B21, A1b, B2bca, B3bca, and C. Fertilized subsoils producing yields similar to their surface soils were: Weld B22; Rago A‐B; and the Keith A1b, B2b, B3bca, Cbca, and C. The remaining fertilized subsoils (Weld B21 and Keith B2 and B2ca) produced less yield than their respective surface soils.
Morphology of Soils With Fragipans in Parts of Wilson County, North Carolina
Authors: Daniels R. B. , Nettleton W. D. , McCracken R. J. , Gamble E. E. 
Published: July 2010

AbstractModerately well to very poorly drained soils in parts of the North Carolina Coastal Plain have subsurface horizons with the physical properties of fragipans. The brittle parts of the fragipan horizons are dense gray loamy sands, sandy loams or silt loams. This dense brittle material occurs in the same horizon with less dense, friable, more clayey materials.Soils with weakly expressed fragipan horizons have an A, Bt, Bt & A′2x, B′tx, and C horizon sequence. Soils with the most strongly expressed fragipan horizons have an A, B, A′2x, B′tx, and C or an A, A2x, Btx, and C horizon sequence. The fragipan horizon in the most strongly expressed pans in places engulfs the overlying B horizon.
Phosphorus Uptake in Young Pitch Pine (Pinus rigida Mill.)
Authors: Voigt G. K. 
Published: July 2010

AbstractPhosphorus sorbed by young pitch pines was related to water‐soluble P, P extracted by 0.002 n H2SO4, by HOAc‐NaOAc or by NH4F‐HCl in the rooting zones of these trees. Average annual P requirements were approximated by the three acid‐extracting agents but water‐soluble P in the root surface zone was considerably less than the annual uptake. Mean P concentration of the soil solution immediately adjacent to the root surface was estimated to be about 0.5 ppm. There appeared to be an interaction between P and Ca which resulted in reduced P uptake with increasing Ca concentration. Increased sorption of both P and Ca was associated with increased root surface. The results suggest that apatite or apatite‐like compounds may have served as a source of P but attempts to verify presence of apatite in the soil were inconclusive.
A Method for Visualizing the Flow of Solutions Through Porous Media
Authors: Knoll K. C. , Hajek B. F. 
Published: July 2010

AbstractGrouting agents which bind particles together were used to demonstrate the flow of solutions through porous media. The grout was infiltered into a soil‐sand fraction, beach sand and spherical glass beads. The solidified masses showed the irregular wetted volume of sand media and the uniform glass bead wetted volume.
Soil Moisture Transport Due to Thermal Gradients: Practical Aspects
Authors: Cary J. W. 
Published: July 2010

AbstractThe present status of knowledge concerning thermally induced transport of moisture in soil is reviewed. This includes the various theories on mechanisms of transport and experimental data showing the magnitude of moisture flow in various porous materials. Wherever possible these data were chosen to show the relative importance of thermal versus head‐type flow and some general trends are noted.Simple equations are developed to describe the thermally induced moisture flow near the soil surface which arises from transient thermal gradients produced by the diurnal temperature cycle. Calculations of the moisture flux over 2 ten‐hour time intervals for a typical field situation indicate that thermal water transport should be considered whenever moisture, salt, or heat fluxes are being studied in the soil's surface layers.The upward flow of soil water against a moisture content gradient in the winter is also considered. A sample calculation of the amount of thermally driven moisture was made using data available in the literature. The result suggested that the thermal moisture flow was too small to account for the net movement of soil moisture into the frost zone.
Effect of Soil Humic Acids on Uptake of Fission Products by Excised Roots
Authors: Tatsukawa Ryo , Franklin R. E. 
Published: July 2010

AbstractTwo‐phase membrane equilibrium systems were used to study complexing of humic acids with fission products and the effect of complexing on the uptake of fission products by excised roots. Humic acids from Rifle peat and an Alaskan peat were purified by centrifugation and resin column treatment. Higher concentrations and greater uptake of the fission products Fe59, Sr90, Ru106, and Cs137 from the Rifle peat humic acid suspensions than from equilibrium dialyzates indicated some form of complexing of the isotopes with the organic matter. The humic acid from the Alaskan peat exhibited very little suspension effect as measured by uptake. The degrees of complexing by the humic acid according to distribution of isotopes in the systems were in the order Fe ≫ Sr > Cs > I. Total uptake and the availability to plants of complexed isotopes tended to be in the reverse order.
The High‐salt‐water Dilution Method for Reclaiming Sodic Soils
Authors: Reeve R. C. , Doering E. J. 
Published: July 2010

AbstractAs a sodic soil is leached with successive dilutions of a divalent cation‐containing high‐salt water, exchangeable sodium is replaced by divalent cations from the leaching solution in accordance with the “valence dilution” principle. Water intake is maintained by the flocculating effect of the electrolyte in the water. Equations are derived that describe the equilibrium exchangeable‐sodium‐fraction of the soil and the depth of water required to effect reclamation in terms of measurable properties of the soil, and the chemical composition of the water. The suitability of a particular water for reclaiming a given soil and the depth of water required can thus be evaluated. The case of constant‐rate dilution is also considered and depth of water equations are written in terms of a dilution‐rate parameter B. The depth of water required to effect reclamation depends upon the ratio R of the divalent cations to the total cations in the available high‐salt water, the total salt concentration of the water, and the dilution rate. The strongest dependence is upon R, with the amount of water required for reclamation decreasing markedly as R increases.
Response of Slash Pine (Pinus elliottii Engelm. var. elliottii) to Phosphorus in Sandy Soils
Authors: Pritchett W. L. , Llewellyn W. R. 
Published: July 2010

AbstractRock phosphate or superphosphate band applied to slash pine about 1 year after transplanting resulted in significant height and diameter increases in 5 of 8 experiments, 3 to 5 years after treatment. However, response occurred only on somewhat poorly to poorly drained (flatwood) sands of the Groundwater Podzol and Humic Gley groups. While 50 lb N/acre applied alone usually suppressed tree growth, when applied in combination with 35 lb P/acre, it resulted in additional response. After the third year, 140 lb P/acre from rock phosphate gave about as good results as 35 lb P/acre from superphosphate. The optimum level of tissue P in current needles of 3‐ to 5‐year‐old trees was approximately 0.10%. Total soil P did not appear to be of much value for predicting response of young pine trees to added P. However, the amount of P extracted from unfertilized surface soil with 1.0N NH4OAc (pH 4.8) was negatively correlated with response to phosphate applications on flatwoods sands. Curvilinear regression lines in relation to tree response to varying levels of fertilizer P with amounts of soil extractable P were constructed.
Diffusion of Salts in Clay‐Water Systems
Authors: Kemper W. D. , van Schaik J. C. 
Published: July 2010

AbstractRates of salt diffusion through homoionic clay plugs were determined after the plugs had been brought to steady state between solutions of the chloride of the cation with which the clay was saturated. Salt and water contents were measured across the clay plugs and were used with the diffusion rates to calculate porous system diffusion coefficients.Diffusion coefficients increased as an exponential function of water content, but for practical purposes, were independent of the salt concentration.Diffusion potentials were measured and calculated. They indicate that the adsorbed cations contribute slightly to the movement of the salt cations.
A Modified Chang and Jackson Procedure for Routine Fractionation of Inorganic Soil Phosphates
Authors: Petersen G. W. , Corey R. B. 
Published: July 2010

AbstractA method is described for the routine fractionation of inorganic soil phosphates. Use of constant suction pipettes, two molybdophosphoric reductants with different sensitivities, and an isobutyl alcohol extraction for the determination of reductant soluble phosphates greatly increased the speed of the phosphorus determinations. Results from 100 deplicated soil samples had average coefficients of variation and correlation between duplicates within samples for the four phosphate fractions of 3.7% and 0.998, respectively.
The Free Energy of Formation of Gibbsite and Al(OH)4‐ from Solubility Measurements
Authors: Kittrick J. A. 
Published: July 2010

AbstractSolubility determinations on two particle sizes of crystalline gibbsite, from both undersaturation and supersaturation in the acid pH range, gave a KSO of −34.03 ± 0.05. Using the same gibbsite in the alkaline pH range and extrapolating values from supersaturation to infinite time, a *KS4 of −15.30 ± 0.05 was obtained. From these values a ΔGf0 (gibbsite) of −274.20 ± 0.06 kcal/mole of Al(OH)3 and a ΔGf0 [Al(OH)4‐ aq] of −310.03 ± 0.07 kcal/mole were calculated. The value for gibbsite confirms previous work on the stability of gibbsite and the new Al(OH)4‐ value eliminates a discrepancy between gibbsite stabilities derived from solubility measurements in the acid and in the alkaline pH range.
Effective Volume of Soil Around Plant Roots Determined from Phosphorus Diffusion
Authors: Olsen S. R. , Watanabe F. S. 
Published: July 2010

AbstractThe effective volume of soil contributing P to the roots was measured from a knowledge of the diffusion coefficient of P, a capacity factor for renewal of the soil solution, and the P concentration in solution. Rate of P uptake per square centimeter of surface area by excised corn roots was measured from P32‐tagged soils at ⅓‐bar moisture suction. The rates of release of resin‐extractable P from the soils were determined. These rates of release of extractable P from the effective volume of soil were much greater than the rate of uptake by the roots. The data indicate strongly that the rate of release of solid phase soil P to the soil solution is a nonlimiting step in the absorption mechanism of P by roots.
Nitrosation of Soil Organic Matter: II. Gas Chromatographic Separation of Gaseous Products
Authors: Stevenson F. J. , Harrison R. M. 
Published: July 2010

AbstractGas chromatographic techniques were developed for separating and determining inorganic gases in experimental systems dealing with losses of soil N. A single column, consisting of acid‐washed chromatographic‐grade coconut charcoal, gave excellent resolution of H2, N2, CO, CO2, N2O, and NO (or O2). The sensitivity of the method for NO and CO was improved considerably by blocking sorption sites responsible for irreversible retention of these gases. Alkyl nitrites did not interfere with the separations.
Soil Chemical Changes and Infiltration Rate Reduction Under Sewage Spreading
Authors: Thomas Richard E. , Schwartz Warren A. , Bendixen Thomas W. 
Published: July 2010

AbstractLaboratory and field lysimeters were used to investigate the site and nature of soil‐pore clogging under sewage spreading. The site of clogging was located by determining with a seepage meter the impedance profile at 0.5‐cm depth intervals. Soil samples were analyzed for sulfide, iron, phosphate, total organic matter, polysaccharide, and polyuronide to evaluate possible causative relationships. The infiltration rate loss exhibited three phases: phase I, a slow reduction under aerobic conditions; phase II, a rapid reduction under anaerobic conditions; and phase III, a further gradual decline under anaerobic conditions. The primary site of clogging was the 0‐ to 1‐cm depth of soil. Although sulfide was an indicator of anaerobic conditions, it was not a primary cause of clogging. Accumulations of the other five measured constituents may contribute to clogging in both phase I and phase II. Organic matter was the only probable clogging agent to decline as the infiltration rate was partially recovered in a rest cycle.
Phase Composition of Frozen Montmorillonite‐Water Mixtures from Heat Capacity Measurements
Authors: Anderson Duwayne M. 
Published: July 2010

AbstractEquations are written that form the basis of a method for determining the unfrozen water content of frozen clay‐water mixtures from heat capacity measurements. The heat capacity of frozen sodium‐montmorillonite water mixtures was determined at −4.7 and −9.6C with a Calve. Microcalorimeter. The data were then used in conjunction with the method described to obtain the unfrozen water content of these clay wate mixtures. The data obtained indicate that the method is applicable at temperatures below about −5C. The amount of unfrozen water found in the frozen clay‐water mixtures at −5 to −10C is quivalent to an interfacial surface layer of water of from one to two molecular diameters in thickness. Most of this water can be accommodated and is though to be located in interlamellar regions.
Effect of Shear on Suction in Saturated Clays
Authors: Day P. R. , Ripple C. D. 
Published: July 2010

AbstractA slurry of clay and water that has remained undisturbed for several days undergoes a rapid lowering of suction when sheared. After shear has ceased the suction increases spontaneously towards the original value at an exponential rate. These effects have been observed in various clay types and in bentonite with various cation treatments.Deformation generally has a strong influence on the suction, whose changes with shear depend upon the preconsolidation or prestress history of the soil. Shearing a clay through an angle of only 2° or 3° may affect its suction markedly.The effect is similar to, and is associated with, the phenomenon of thixotropy. The present measurements furnish support for the theory that shear causes rupture or displacement of the structural bonds of clay‐water systems and, perhaps more significantly, that the structures tend to reform spontaneously.
The Effect of Carbon Dioxide on the Chemisorption of Ammonia by Base‐saturated Clays
Authors: du Plessis M. C. F. , Kroontje Wybe 
Published: July 2010

AbstractThe presence of CO2 increased and stabilized the effective retention of ammonia, applied as aqua ammonia, by base‐saturated clays. Ca2+‐ and Mg2+‐bentonites particularly showed a striking increase in the retention of ammonia in the presence of CO2.It is postulated that the Ca2+ and Mg2+ exchanged by ammonia, are precipitated as highly insoluble compounds thus stabilizing the retention of chemisorbed ammonia.
Decomposition of Carbon‐14 Labeled Atrazine in Soil Samples from Sanborn Field
Authors: Wagner G. H. , Chahal K. S. 
Published: July 2010

AbstractSoil samples from corn (Zea mays) and from timothy (Phleum pratense) plots of Sanborn Field, with and without glucose added, were incubated for 6 months after treating with 10 ppm of C14 ring‐labeled atrazine. During the incubation period, < 2% of the ring carbon of atrazine was evolved as CO2 from the glucoseamended soils and < 1% from the unamended soils. The rate of C14O2 evolution from the corn soil did not vary greatly throughout the incubation, whereas, for the timothy soil it peaked at 1 week and then rapidly declined. Evolution of CO2 from glucose and native organic matter was not influenced by the atrazine treatment. Recovery of unchanged atrazine after concluding the incubation averaged about 10% of that initially added. The bulk of the added C14 was not extracted in the course of making these measurements but its persistence in the soil was confirmed by total combustion.