bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water and Salt Flow Through Compacted Clays: I. Permeability of Compacted Illite and Montmorillonite
Authors: Rolfe P. F. , Aylmore L. A. G. 
Published: July 2010

AbstractStudies have been made of the pressure‐induced flow of the chloride solutions of various monovalent, divalent and trivalent cations, at various concentrations, through compressed Wyoming bentonite and Willalooka illite cores.The majority of the measurements were carried out on the Willalooka illite core and its permeability has been shown to depend markedly on the nature and concentration of the cations present, with three‐ to fourfold variations being observed in some instances. At the lower electrolyte concentrations permeability increases in the order Na < Ca < Ba < La < Cs at a given concentration. In addition the permeability increases linearly with flow pressure to an extent ranging from some 15% for the Na systems to 97% for the 3.0M LaCl3 system over the pressure range examined.The contributions to the permeability changes arising from mechanical expansion of the flow cell, particle rearrangements and the electroviscous effect have been shown to be quite inadequate to account for the major changes observed. It is suggested that the most significant effects arise as a result of the influence of cationic size, charge, and concentration on the viscosity of the several layers of coerced water which form adjacent to the clay surfaces. Coercion of water may arise partly through its association with the exchangeable cations adsorbed on the surface or forming diffuse double layers, but mainly from the preferred or unique water structure developed in proximity to the clay surface. In particular increasing concentrations of Cs, Ca and La cations appear to cause a pronounced breakdown in water structure within the pores.
An Alkaline Oxidation Method for Determination of Total Phosphorus in Soils
Authors: Dick W. A. , Tabatabai M. A. 
Published: July 2010

AbstractA simple and precise method for determination of total phosphorus in soils and lake sediments is described. A mixture of soil and sodium hypobromite solution is boiled to dryness in a sand bath (260–280°C), and the total amount of orthophosphate is extracted with 1N H2SO4 and determined colorimetrically by the molybdenum blue method. Analysis of a group of diverse soil, lake sediment, and sewage sludge samples indicated that the proposed method and the HClO4 digestion method give essentially the same total P values. With 10 soils, the average results by the proposed NaOBr oxidation method were 1% higher than those obtained by the HC1O4 digestion method and 4% lower than those obtained by the Na2CO3 fusion method. A comparison of methods used for colorimetric determination of the orthophosphate extracted indicated that the results by the recently developed method by Dick and Tabatabai agree closely with those obtained by the method of Murphy and Riley. Digestion of samples with sodium hypobromite solution and colorimetric determination of the extracted P by the method of Murphy and Riley permits rapid analysis of a large number of samples at one time.
Determining Cation Exchange Capacity: A New Procedure for Calcareous and Gypsiferous Soils
Authors: Polemio Mario , Rhoades J. D. 
Published: July 2010

AbstractA new, two‐step procedure is presented for determining the cation exchange capacity (CEC) of calcareous and gypsiferous soils. The method eliminates most of the errors inherent in conventional methods. The cation exchange sites are saturated with sodium by four successive “equilibrations” of the soil (4–5 g) with 33‐ml increments of a pH 8.2, 60% ethanol solution of 0.4N NaO Ac − 0.1N NaCl (saturating solution). The saturated sample then is extracted with three 33‐ml increments of 1.0N, pH 7 magnesium nitrate. Total sodium (Nat) and chloride (Clt) are subsequently determined in the extracted solution. Chloride (Clt) is determined so that the soluble sodium (Nasol), from the excess saturating solution carried over from the saturation step to the extraction step, may be deducted from the total sodium (Nat) to obtain exchangeable sodium (Naexch), which is equivalent to the CEC. Thus, CEC = Naexch = (Nat − Nasol) = Nat − [Clt(Na/Cl)saturating solution] where (Na/Cl)saturating solution is the ratio of Na to Cl in the saturating solution.
Short‐term Replenishment of Soil Solution Phosphorus
Authors: Peaslee D. E. , Ballaux J. C. 
Published: July 2010

AbstractDepletion of soil solution P from zones around plant roots indicates that diffusive flux of P from the soil solution to the plant root is inadequate to keep pace with removal by plant roots. Consequently, the concentration and/or concentration gradients of solution P maintained under conditions of repeated removal over time are an important soil property that is a factor in determining the quantity of P diffusing to root surfaces. This study was conducted to determine the P release characteristics of five soils differing in P retention properties and pretreated with quantities of P equivalent to their sorption maxima.Five‐gram samples were sequentially extracted with 3.5‐ml aliquots of 10−3N CaCl2 for 350, 15‐min cycles. Quantities of extracted P were 15 to 30% of the added P. Concentrations maintained during repeated extractions revealed three distinct phases of release presumably associated with different forms of soil P. Release persisted through approximately 25, 125, and 150 extraction cycles for the initial, intermediate, and final phases, respectively. For different soils, concentrations of P ranged from 0.5 to 1.1 µg/ml in initial phases and 0.02 to 0.08 µg/ml in final release phases. Though pretreatment of soils with P was based on retention properties, relative extractability and concentrations in solution during release phases appeared to be a characteristic of each soil. During the intermediate release phase, P concentration was very high and decreased rapidly for one soil, was moderately high and stable for another soil, and was very low and hardly discernible from the final phase for a third soil.
Observed and Predicted Rates of Phosphorus Diffusion in Soils of Varying Bulk Density and Water Content
Authors: Hira G. S. , Singh N. T. 
Published: July 2010

AbstractThe self‐diffusion coefficient of phosphorus (D) was measured at bulk densities of 1.25, 1.45, 1.60 and 1.75 g/cm3 and at three levels of soil water content in Choa sandy loam and Haibowal silty clay loam. The tortuosity factor was calculated from the self‐diffusion coefficient of 36Cl. Appropriate values of the adsorption isotherm and the tortuosity factor were used to predict P diffusion coefficient in both soils.The tortuosity factor increased with increase in soil bulk density and increase in water content from 7 to 18% in the Choa soil and 14 to 25% in the Haibowal soil. As bulk density increased from 1.25 to 1.60 g/cm3, the observed diffusion coefficient values averaged over all water contents, increased from 0.05 × 10−10 to 0.31 × 10−10 and 2.13 × 10−10 to 5.07 × 10−10 cm2/sec in Choa and Haibowal soils, respectively. Further increase in bulk density to 1.75 g/cm3 decreased the diffusion coefficient. At high bulk density changes in water content affected the self‐diffusion coefficient of P in both soils to a greater extent than at low bulk density. The phosphate ion‐soil particle interaction was minimum at a soil bulk density of 1.60 g/cm3.
Techniques for Determining Root Length Infected by Vesicular‐arbuscular Mycorrhizae
Authors: Ambler J. R. , Young J. L. 
Published: July 2010

AbstractTechniques were adapted and combined to estimate root lengths and total root length with vesicular‐arbuscular (VA) mycorrhizal infection. Steps include separating roots quantitatively from known volumes of soil, cutting roots into short segments to allow subsampling and mounting, clearing tissue in 10% KOH, staining fungi with trypan blue, subsampling root segments suspended in glycerol by using a syringe, spreading root segments in a counting/observation chamber (made easily from 80 × 100 mm lantern‐slide cover glasses), and line‐intersection counting of segments during microscopic examination. Root lengths with and without fungal infection are calculated from the counts. Root hairs, tips, branching, diameters, cell outlines, and condition of the cortex and stele are microscopically visible in the cleared, stained roots. Consequently, the method offers potential for quantifying several important root characteristics. Data collected from roots of Festuca arundinacea Schreb. are presented as an example.
Stabilization of Calcium by Surface Charge Variation in an Oxisol
Authors: Munns D. N. , Fox R. L. 
Published: July 2010

AbstractIn the surface layer of a Ca‐deficient, fine‐textured Hawaiian Oxisol, concentrations of Ca in solution were poised against tendencies to increase with liming in the pH‐range 5–6, and to decrease with dilution in the range of water content 0.35 to 2.0. Effects of lime and water content on the distribution of Ca between solid phase and solution were shown to be quantitatively consistent with effects of pH and ionic strength on exchange capacity.Relationships between soil pH, cation exchange capacity, and dissolved Ca were determined in soil samples taken from a field‐liming trial. Effects of ionic strength on exchange capacity were determined by summation of adsorbed metal cations after equilibration of soil samples in different salt solutions. Effects of water content on cations in solution were determined by analysis of solutions centrifugally extracted at various water contents.The results help explain why Ca‐deficiency may sometimes be corrected better by neutral Ca salts than by lime and why saturation‐extract Ca may approximate soil‐solution Ca adequately for diagnostic purposes.
The Solubilities of Carbonates and Phosphates in Calcareous Soil Suspensions
Authors: Marion G. M. , Babcock K. L. 
Published: July 2010

AbstractPreviously reported discrepancies between measured soil carbonate and phosphate activity products and the solubility products of pure crystalline minerals may, in part, be attributable to the incomplete characterization of ion‐pairs in solution.Up to 50% of the soluble PO4 and significant amounts of Ca, Mg, and SO4 were present as ion‐pairs. Ignoring ion‐pairs resulted in significant differences in calculated activity products for both carbonates and phosphates.One soil was undersaturated and two were supersaturated with respect to calcite. Calcite was the only carbonate mineral identified by X‐ray diffraction measurements. Calcium carbonate activity products were highly correlated to Mg activities. Magnesium‐calcite apparently controlled the solubility of soil carbonate. The soil phosphate activity products fell between the solubility products of octacalcium phosphate and hydroxyapatite. The phosphate solubility data were compatible with, but not proof of, the presence of calcium phosphate minerals in soils.
Basicity of Exchangeable Aluminum, Formation of Gibbsite, and Composition of the Exchange Acidity in the Presence of Exchangers
Authors: Veith J. A. 
Published: July 2010

AbstractMontmorillonite, vermiculite, and a sulfonic resin were treated with different concentrations of Al(OH)BCl3‐B with the basicity B ranging from 0 to 2.2. The Al exchanged by vermiculite and the resin was always the nonbasic Al3+, independent of B and the amounts of Al(OH)BCl3‐B added. The Al exchanged by montmorillonite was Al3+ when exchanged from Al(OH)BCa0.5B‐montmorillonite containing 32 mmoles Al/100 meq CEC and became basic when large amounts of Al(OH)BCl3‐B had been added before the exchange reaction. In contrast to vermiculite and the resin, the montmorillonite adsorbed preferentially relatively large OH‐Al polymers and, therefore, accumulated much more Al in the interlayers than vermiculite and resin which excluded large OH‐Al polymers because of their smaller d spacings and/or high charge densities. When more OH‐Al accumulated in the interlayers of montmorillonite, the Al was adsorbed less strongly, and relatively large amounts of basic Al became exchangeable. It was shown also that an Al3+‐saturated vermiculite is much more unstable than an Al3+‐montmorillonite. These results are employed to discuss the widely‐observed formation of gibbsite when smectite reacts with basic Al. Finally, the exchange acidity from an Al‐saturated exchanger was shown to consist of both Al3+ and H+. The protons come from (i) the hydrolysis of exchanged Al3+ which, in turn, can be readsorbed as OH‐Al; (ii) from the hydrolysis of adsorbed Al; and (iii) by the exchange of H+ from permanent charges. The latter portion mechanism provides an amount of exchangeable acidity that, if it exists, is relatively small.
Absence of Local Equilibrium During Ammonium Transport in a Soil Column
Authors: Ardakani M. S. , McLaren A. D. 
Published: July 2010

AbstractAdsorption of NH4+ from a stationary solution phase by a Hanford soil approached an equilibrium state exponentially after about 30 min. By contrast, a local equilibrium did not exist between NH4+ in a moving solution phase and soil in a column while a 75‐ppm NH4+‐N solution was delivered at a constant flow rate for 26 days. Local equilibrium, however, was established when the downward solution flow was stopped by setting the column horizontally 1 hour before sampling. Thus, the generality of the assumption of instantaneous equilibrium for cations in moving soil solutions is questioned.
Interactive Effect of Salinity and Phosphorus on Sesame
Authors: Cerda Antonio , Bingham F. T. , Hoffman G. J. 
Published: July 2010

AbstractA solution culture experiment was conducted with a short‐season sesame [Sesamum indicum L. (Selection 333)] to observe interactive effects of osmotic potential (−0.4, −1.4, −2.4, and −4.4 bars NaCl added to a complete nutrient solution), and P concentration (0.5, 5, 25, and 50 mg P/liter) on water relations, mineral nutrition, and yield characteristics. Salinity reduced yields linearly with a 50% decrease in pod yield at an osmotic potential of approximately −2.7 bars. Increasing P concentrations increased yields only at low salinity levels; at higher salinity levels, yields decreased progressively as P increased. Salt tolerance was reduced by the higher P additions.A multiple regression equation for pod yield as a function of salinity and P in combination was developed (R2 = 0.76). Leaf water potential at the early flowering stage decreased with pod yield as salinity and P concentrations increased. Leaf NO3 concentrations decreased as salinity increased.
Plant Uptake of Indigenous and Fertilizer Nitrogen from a Cretaceous Shale and Coal Mine Spoils
Authors: Reeder Jean Dolan , Berg W. A. 
Published: July 2010

AbstractBarley (Hordeum vulgare L.) was grown in a greenhouse in incubated and nonincubated samples of a Cretaceous shale, two strip mine coal spoils, and a soil (Cryoboroll) to evaluate the significance to plant growth of indigenous N mineralization and utilization of added NH4+. These “soil” materials contained 730 to 1,190 ppm total N. Plants grown in the shale or fresh spoil took up less indigenous N than plants grown in vegetated spoil or in soil. Incubation did not significantly affect uptake of indigenous N from any of the four “soil” materials.Less N added as NH4+ was taken up by barley growing in incubated than nonincubated samples of shale, fresh spoil, and vegetated spoil. Total‐N uptake from incubated “soil” material was positively correlated with NH4+‐N + NO3‐‐N contents of “soil” material samples after laboratory incubation for 12, 21, and 42 days.This study indicated that while initial plant recovery of fertilizer N from the geologic materials equaled that recovered from the soil, fertilizer N added to the geologic material may be less available to plants with time than the same amount of fertilizer N added to soil. The high correlations between mineral N contents of laboratory‐incubated samples and total N uptake by barley grown under greenhouse conditions suggested that laboratory incubation tests could be useful in estimating the plant‐available N potentials of certain drastically disturbed lands prior to extensive revegetation programs.
Nitrogen Mineralization and Nitrification in a Cretaceous Shale and Coal Mine Spoils
Authors: Reeder Jean Dolan , Berg W. A. 
Published: July 2010

AbstractKnowledge of rates and amounts of N mineralization in geologic strata is needed to predict N availability to plants when these materials are disturbed by mining or construction and left as surface or subsurface plant‐growth media. Laboratory incubations were conducted to determine ammonification and nitrification rates in a Cretaceous shale, two strip‐mine coal spoils, and a soil from a strip mine in northwestern Colorado. The total N concentration in the soil (1193 ppm), a vegetated spoil (1,083 ppm), and the shale (1112 ppm) were similar, while that of the fresh spoil was lower (730 ppm). No net N mineralization was measured in the shale, and less than 6 ppm NO3‐‐N accumulated in the fresh spoil during a 168‐day incubation. However, net mineralization of 49‐ppm NO3‐‐N was found in the vegetated spoil and 75‐ppm NO3‐‐N in the soil during the same incubation period.Nitrification of added NH4+ (60 ppm NH4+‐N) was measured in the shale, spoils, and soil. Accumulated levels of NO3‐‐N were 100 ppm in the vegetated spoil and 117 ppm in the soil after a 168‐day incubation. However, only 36‐ppm NO3‐‐N accumulated in the fresh spoil and no NO3‐‐N accumulated in the shale during the same incubation period.Rates and total amounts of CO2 evolution from the geologic materials resembled that from the soil, indicating considerable heterotropic microbial activity in these geologic materials. The addition of NH4+ did not significantly affect the rate or amount of CO2 evolution from the geologic or soil materials, indicating that heterotropic microorganisms were capable of using the forms of N present in the geologic materials.
Subgroup Designation of Three Udolls in Southeastern Nebraska
Authors: Lewis David T. 
Published: July 2010

AbstractThe Wymore, Pawnee, and Mayberry soil series are presently placed within the fine montmorillonitic mesic family of Aquic Argiudolls. However, the major properties of these soils that affect their interpretations are related to a clay content in the argillic horizon that exceeds 40%, a consequent high shrink swell potential, and a droughty nature. The wide cracks that develop during most summer seasons affect runoff and water entry into the profile thereby making the moisture control section meaningless in them. COLE and potential linear extensibility values for these soils along with their other properties suggest that perhaps Vertic of Ustertic subgroup designations would more accurately describe their properties and interpretation of these properties.
Soil Salinity—Four‐electrode Conductivity Relationships for Soils of the Northern Great Plains
Authors: Halvorson A. D. , Rhoades J. D. , Reule C. A. 
Published: July 2010

AbstractInfluence of soil texture, soil geographic location and parent material, and calibration method on the linear ECe‐ECa relationship was investigated. Linear regression relationships between saturation extract electrical conductivity (ECe) and bulk soil electrical conductivity (ECa) as measured by the four‐electrode technique were developed for northern Great Plains soils. Most correlation coefficients (r) exceeded 0.95 and all were significant at the 0.01 probability level. Geographic location had little effect on the ECe vs. ECa relationship; therefore, an ECe vs. ECa calibration made for a soil textural class at one location will apply to another location having a similar range in soil water, clay content, and salinity. Clay content affected linear regression line slopes more than did other factors investigated. Regression slopes varied from 3.06 for a clay to 12.99 for a loamy sand over the clay concentration range of 63.0 to 6.5%, respectively.To minimize adverse effects caused by natural variation in soil texture, water content, and salinity when making field ECe vs. ECa calibrations, we suggest artificial salinization of columns of the soil type in question, which will permit subsequent analysis of the soil by either the cell or EC‐probe calibration method.
A Direct Field Measurement of Ammonia Emission After Injection of Anhydrous Ammonia
Authors: Denmead O. T. , Simpson J. R. , Freney J. R. 
Published: July 2010

AbstractStudies of the efficiency of applications of anhydrous ammonia fertilizer require a measurement of ammonia retention or loss at the time of application. Because of sampling problems, conventional measurements based on soil analysis are difficult to make in the field. A new method is described, based on calculating the aerial transport of ammonia across the downwind edge of the treated field from measurements of wind speed, wind direction, and atmospheric ammonia concentration. Ammonia losses as small as 1 kg N/ha can be easily detected. Maximum errors are reckoned at no more than 20%. In a field experiment in which anhydrous ammonia was applied at 107 kg N/ha, aerial sampling gave a loss of 1 kg N/ha. Soil sampling detected no loss because of a large sampling error (SE 15 kg N/ha).
Organic Phosphate Transport and Hydrolysis in Soil: Theoretical and Experimental Evaluation
Authors: Castro C. L. , Rolston D. E. 
Published: July 2010

AbstractAn understanding of the movement, hydrolysis, and retention of organic phosphates in soils is necessary to evaluate possible advantages of the compounds as fertilizers, based upon their characteristic of increased vertical movement over that of inorganic phosphates when applied with irrigation water. Pulses of chloride and glycerophosphate were applied to 4‐, 10‐, and 20‐cm long Panoche clay loam (Typic Torriorthents) soil columns maintained slightly water‐unsaturated (soil‐water pressure = −0.018 bar). The concentration of glycerophosphate in the pulse applications varied from 386 to 1,110 ppm P. An analytical solution assuming first‐order kinetics and a reversible, linear isotherm for glycerophosphate hydrolysis and sorption, respectively, was compared with measured glycerophosphate concentrations in the column effluent. An analytical solution of the coupled equations for simultaneous transport of organic phosphate and orthophosphate assuming a linear, reversible isotherm for orthophosphate adsorption is given. This solution was compared with measured orthophosphate concentrations in the effluent from a continuous application of glycerophosphate to a 2‐cm long column. Organic phosphate adsorption on soil colloids was effectively separated from organic phosphate hydrolysis using displacement techniques. The magnitude of the fitted, first‐order constant for hydrolysis was dependent upon the initial concentration of the influent solution indicating that first‐order kinetics may not be applicable for high organic phosphate concentrations. The magnitude of the fitted, adsorption‐desorption constant for glycerophosphate was dependent upon concentration indicating that adsorption‐desorption was nonlinear. The nonlinearity of glycerophosphate adsorption‐desorption was verified from an equilibrium, adsorption isotherm. The magnitude of the fitted orthophosphate sorption constant for coupled glycerophosphate and orthophosphate transport was considerably larger than that determined from a 6‐day equilibrium adsorption isotherm.