Personal Research Database

Full Text: 1960-80\Soi Sci Soc Ame J42, 668.pdf

? Shayan, A. and Davey, B.G. (1978), Universal dimensionless phosphate adsorption isotherm for soil. Soil Science Society of America Journal, 42 (6), 878-882.

Full Text: 1960-80\Soi Sci Soc Ame J42, 878.pdf

Abstract: A unique dimensionless phosphate adsorption isotherm, covering the solution concentration range 10^–6 to 10^–1 M P, which has been found to fit 17 materials including 15 soils, pure kaolinite and amorphous Al(OH)₃, is derived. The soils shown to fit the isotherm include chromic luvisols, pellic vertisols, calcic luvisols, a tropeptic eutrorthox, a volcanic ash soil from New Zealand, and a number of English soils. The necessary parameters to derive, a complete adsorption isotherm for a particular soil, from the universal isotherm, requires three adsorption experiments in the high concentration range (10^–4 to 10^–1 M P) to define the linear portion of the isotherm and the critical concentration. Three other determinations in the range 10^–6 to 10^–4 M P are needed to obtain the Freundlich isotherm from the data after correction for the effect of the linear region of the isotherm at high concentration. The Freundlich constant a was shown to be a capacity factor, and the constant b to be related to the chemical potential of the phosphate in solution. For the soils studied the variation in the magnitude of b was found to be smaller (0.11 to 0.37) than in a (1.60 to 9.66). The advantage of this universal isotherm over conventional isotherms, is that it requires less experimental work to define and is applicable over a wide range of P concentrations such as might be found surrounding a fertilizer granule.

Bloom, P.R. and McBride, M.B. (1979), Metal ion binding and exchange with hydrogen ions in acid-washed peat. Soil Science Society of America Journal, 43 (4), 687-692.

Full Text: 1960-80\Soi Sci Soc Ame J43, 687.pdf

Abstract: Titration and electron spin resonance (ESR) studies of metal ion adsorption processes on acid peat were used to investigate metal-proton exchange. Localization of ions at carboxylate sites is suggested but the data indicate that chelation mechanisms or sites of greatly different acid strength need not be involved. The peat is observed to behave very much like synthetic cross-linked polycarboxylic acids in terms of metal ion adsorption. Most of the divalent ions adsorbed at acid pH appear to maintain a hydration sphere while the strongly immobilized Cu²⁺ ion coordinates directly with functional oxygens of the peat.

Sparks, D.L., Zelazny, L.W. and Martens, D.C. (1980), Kinetics of potassium exchange in a paleudult from the coastal plain of Virginia. Soil Science Society of America Journal, 44 (1), 37-40.

Full Text: 1960-80\Soi Sci Soc Ame J44, 37.pdf

Abstract: The kinetics of K adsorption from solution to exchangeable phases were investigated on the Ap, A2, B21t, and B22t horizons of Dothan soil (Plinthic Paleudult) from two locations in Virginia. These soils are loamy sands in the upper horizons with clay content increasing with depth, are slightly acidic in the surface with pH decreasing with depth, have CEC’s ranging from 3.4 to 8.6 meq/100 g in the four horizons and contain considerable quantities of chloritized vermiculite and kaolinite in all horizons. Potassium adsorption with time was evaluated on Al- and Ca-saturated samples from each horizon using 5, 25, and 100 µg/ml K solutions equilibrated for 0, 1, 2, 24, 96, and 192 hours. Equilibrium in K exchange was reached in 2 hours with the 5 and 25 µg/ml solutions and in about 24 hours with the 100 µg/ml solution. This slow rate of K exchange was attributed to diffusion-controlled exchange, which reflects the relatively high amount of vermiculitic material in these soils. Adsorption rate coefficients (ka) were calculated from reaction time vs. quantity of K sorbed using a modified form of the Freundlich equation. The magnitude of the ka values decreased with increasing ionic strength, which conforms to Bronsted’s activity rate theory. The similar magnitude of the ka values from horizon to horizon suggests that similar exchange reactions were taking place in all horizons.

Chien, S.H., Clayton, W.R. and McClellan, G.H. (1980), Kinetics of dissolution of phosphate rocks in soils. Soil Science Society of America Journal, 44 (2), 260-264.

Full Text: 1960-80\Soi Sci Soc Ame J44, 260.pdf

Abstract: A modified Elovich equation in the form of Ct = C0 – (1/ß)ln (ß) – (1/ß) ln t was derived to describe the kinetics of dissolution of three phosphate rocks (North Carolina, central Florida, and Tennessee) in three soils (one soil from Florida and two Nigerian soils). The equation fitted the experimental data the best among various models of kinetics. Comparisons of dissolution rates of various phosphate rocks in a given soil or a given phosphate rock in various soils can be made by comparing the values of three parameters—C0, and ß—in the equation where C0 is the maximum P concentration in the soil solution that a phosphate rock can provide in a soil (Ct is the P concentration at time t), and and ß are constants. It was found that C0 increased as increased and/or ß decreased in a given system. Temperature was found to have no significant effect on the dissolution of phosphate rock in the soil. This implies that phosphorus retention by the tropical soils treated with phospate rock may be much less affected by temperature as compared with water-soluble P fertilizers such as concentrated superphosphate.

Notes: highly cited

Chien, S.H. and Clayton, W.R. (1980), Application of Elovich equation to the kinetics of phosphate release and sorption in soils. Soil Science Society of America Journal, 44 (2), 265-268.

Full Text: 1960-80\Soi Sci Soc Ame J44, 265.pdf

Abstract: Experimental data on the phosphate release and sorption in soils, when inadequately described by a first-order kinetic reaction, are often interpreted as a combination of two or three simultaneous first-order reactions. A simple modified Elovich equation in the form: q = (1/ß) ln (ß) + (1/ß) ln t was derived to fit the reported experimental data in literature that failed to conform to a single first-order kinetic equation. In this equation, q is the amount of phosphate released or sorbed, and and ß are constants. The equation successfully described the data as a single straight line that covers the entire course of reaction time. It also appears that constants of and ß may be used for comparison of reaction rates of phosphate release or sorption in different soils.

? Sposito, G. (1980), Derivation of the Freundlich equation for ion exchange reactions in soils. Soil Science Society of America Journal, 44 (3), 652-654.

Full Text: 1960-80\Soi Sci Soc Ame J44, 652.pdf

Abstract: The Freundlich adsorption isotherm equation is derived rigorously for the trace adsorption of an ion participating in an exchange reaction. The derivation, which is an application of some general results obtained by R. Sips, is based on the assumption that the exchanger surface is heterogeneous and that each class of exchange sites adsorbs individually accordingly to the Langmuir isotherm. It is shown that, under these conditions, the Freundlich isotherm corresponds uniquely to a distribution of relative adsorption site affinities which is essentially log normal and that the empirical parameters in the Freundlich equation may be used to characterize the site distribution function mathematically, thus giving information about surface heterogeneity in the exchanger.

Sparks, D.L., Zelazny, L.W. and Martens, D.C. (1980), Kinetics of potassium desorption in soil using miscible displacement. Soil Science Society of America Journal, 44 (6), 1205-1208.

Full Text: 1960-80\Soi Sci Soc Ame J44, 1205.pdf

Abstract: Kinetics of K desorption were conducted on samples from the Ap, A2, B21t, and B22t horizons of two Dothan (Plinthic Paleudults) soils. Aluminum- and calcium- saturated samples were equilibrated with K for 96 hours and then continuously leached with 0.01M CaCl₂ until K was not detected in the leachate. The rate of K desorption from all samples increased rapidly initially and levelled off with time. Desorption was nearly complete in approximately 3 to 4 hours for the Ap, A2, and B21t horizons, and in 8 to 9 hours for the B22t horizons. Approximately 95–98% of the adsorbed K was subsequently desorbed suggesting K adsorption-desorption in the Dothan soils was reversible. A linear relationship between time and percent K desorption indicated that diffusion was the predominant mechanism of K desorption in these soils. Diffusion-controlled exchange would be expected due to the vermiculitic clay minerals present in the soils. Potassium desorption conformed to first-order kinetics. Apparent desorption rate coefficients (k’d) ranged from 0.3 to 1.3 hour^–1. The magnitude of the k’d values decreased as clay content increased in the soils. This was ascribed to increased intraparticle transport and to increased diffusion in the more clayey samples. The k’d values were generally higher in the Al-than in the Ca- saturated samples. The effect of flow velocity on rate of K desorption was investigated using velocities of 0.5, 1.0, and 1.5 ml min^–1. The rate of K desorption increased only slightly with flow velocity.

? Sharpley, A.N., Ahuja, L.R., Yamamoto, M. and Menzel, R.G. (1981), The kinetics of phosphorus desorption from soil. Soil Science Society of America Journal, 45 (3), 493-496.

Full Text: 1981\Soi Sci Soc Ame J45, 493.pdf

Abstract: The kinetics of P desorption for several soils was investigated at different water/soil ratios, during a short period of time, so that the results could be related to P release from agricultural soil to rainfall and runoff water. For all soils the logarithm of P release (Pd) was linearly related to the logarithm of contact time (t) at any given water/soil ratio (W) and P amendment and to logarithm of W at any given contact time and P amendment. The amount of P released was also directly proportional to the amount of desorbable P (Po) in the soil initially. The following simplified empirical model was developed to describe the desorption of soil P,

Pd = KPotWß,

where K, and ß are constants. The simplified model gave a reasonably good description of P desorption from five southwestern soils and provided similar values of the constants K, and ß, for each soil, over a range of experimental conditions. Consequently, we suggest that average values of the constants for each soil can be used in the model to describe P release for general applications.

Feigenbaum, S., Edelstein, R. and Shainberg, I. (1981), Release rate of potassium and structural cations from micas to ion exchanges in dilute solutions. Soil Science Society of America Journal, 45 (3), 501-506.

Full Text: 1981\Soi Sci Soc Ame J45, 501.pdf

Abstract: The rate of release of K and structural cations from three micas (biotite, phlogopite, and muscovite) was measured in two-particle size ranges (5 – 20 µm and 20 – 50 µm), in dilute electrolyte solutions (0.001 N), and at pH 3.0 and 7.0. The rate of K release from phlogopite and biotite was similar to the rate of release of structural cations under acidic conditions and significantly higher under neutral conditions. These findings indicate that structural decomposition of phlogopite and biotite is dominant in acidic conditions, and that the role of interdiffusion increases in neutral conditions. Decomposition was more sensitive than interdiffusion to particle size. The rate of K-release from muscovite was about 5 and 15% that from biotite and phlogopite, respectively. The rate of K release from muscovite was higher than the rate of Al release. This indicates that muscovite is the most stable of the three micas and that the decomposition mechanism for K-release in muscovite was less important.

Sparks, D.L. and Jardine, P.M. (1981), Thermodynamics of potassium exchange in soil using a kinetics approach. Soil Science Society of America Journal, 45, 1094-1099.

Full Text: 1981\Soi Sci Soc Ame J45, 1094.pdf

Abstract: Thermodynamics of potassium (K) exchange using a kinetics approach was investigated in Ca-saturated samples from the Ap and B21t horizons of a Matapeake soil from Delaware. Kinetics of adsorption and desorption were determined at temperatures of 0, 25, and 40°C on each soil horizon using a miscible displacement technique. Energies of activation for adsorption and for desorption (Ea and Ed, respectively) ranged from 3.83 to 5.52 kcal mol^-1. The Ed values were higher than the Ea values, indicating that more energy was needed to desorb K than to adsorb K. Thermodynamic and pseudothermodynamic parameters were determined using Gibbs’ and Eyring’s reaction rate theories. The free energy for K exchange (G°) values were negative (ranging from 1,155 to 1,294 cal mol^-1) and increased with increasing temperature. The free energy of activation values were higher for K desorption (G_d) than for K adsorption (G_a), suggesting a greater free energy requirement to desorb K. The excellent agreement between G° calculated from Gibbs’ theory and from Eyring’s reaction rate theory indicated that pure thermodynamic parameters could be calculated using a chemical kinetics approach. The enthalpy (H°) values were exothermic and indicated stronger binding of K’ ions in the B21t horizon than in the Ap horizon of the Matapeake soil. The latter was related to the difference in external surface-to-interlayer surface-charge ratio in the two horizons. The enthalpy of activation (H⁺⁺) values in both horizons were higher for desorption (H_d⁺⁺), than for adsorption (H_a⁺⁺), suggesting the heat energy required to overcome the K desorption barrier was greater than for that of K adsorption.

Boyd, S.A., Sommers, L.E. and Nelson, D.W. (1981), Copper(II) and iron(III) complexation by the carboxylate group of humic acid. Journal Soil Science Society of America, 45 (6), 1241-1242.

Full Text: 1981\Soi Sci Soc Ame J45, 1241.pdf

Abstract: Infrared (IR) spectroscopy, between 2,000 and 1,000 cm^–1, was used to identify the mode by which carboxylates of a soil humic acid (HA) complexed Cu²⁺ and Fe³⁺. Carboxylic acid groups of HA (R-COOH) were converted to carboxylates (R-COO-) by forming coordinate bonds with Cu²⁺ and Fe³⁺. The separation of the antisymmetrical and symmetrical stretching vibrations of R-COO- was obtained from the IR spectra of the metal-HA complexes. The values for the metal-HA complexes were significantly larger than the corresponding reference value of for uncomplexed -COO-, demonstrating that R-COO- formed a unidentate complex (i.e., a single M-O bond) with Cu²⁺ and Fe³⁺. The formation of bidentate or bridging complexes between R-COO- of HA and Cu²⁺ or Fe³⁺ was not observed.

Onken, A.B. and Matheson, R.L. (1982), Dissolution rate of EDTA-extractable phoaphate from soils. Soil Science Society of America Journal, 46 (2), 276-279.

Full Text: 1982\Soi Sci Soc Ame J46, 276.pdf

Abstract: The kinetics of phosphorus (P) dissolution in EDTA (ethylenedi-aminetetraacetic acid) solution were investigated for several soils for the purpose of determining if the dissolution rate constants could be related to crop response to applied P. Eight kinetic models were evaluated using coefficients of determination (R2) and standard errors of estimate (SE). Additionally, the effects of temperature and soil-solution ratio on P dissolution in the EDTA solution were determined. Relatively high values of R2 and low values of SE indicated that P dissolution in EDTA solution for the soils used was most often best described by the two-constant rate equation, the Elovich-type equation, and the differential rate equation. None of the models best described the dissolution for all soils. Using R2 and SE for evaluation, the best relationships found between dissolution rate constants and yield response to applied P were for the two-constant rate equation (R2 = 0.97, SE = 2.58) and the differential rate equation (R2 = 0.95, SE = 2.69). Soil-solution ratio affected the values of dissolution rate constants, with those obtained from the differential rate equation most sensitive. The Arrhenius equation described reasonably well the effect of temperature on values of the dissolution rate constants.

Sparks, D.L. and Rechcigl, J.E. (1982), Comparison of batch and miscible displacement techniques to describe potassium adsorption kinetics in Delaware soils. Soil Science Society of America Journal, 46 (4), 875-877.

Full Text: 1982\Soi Sci Soc Ame J46, 875.pdf

Abstract: Kinetics of potassium (K) adsorption in three soils were compared using batch equilibrium and miscible displacement techniques. The batch method reached equilibrium sooner than miscible displacement in all cases. Greater clay content did not affect the equilibrium time using the batch technique but increased that time for miscible displacement. The percent-K adsorption was closely related to (time)1/2 indicating diffusion-controlled exchange. Relative rate coefficients were significantly higher for batch than for miscible displacement. Miscible displacement simulates solute movement in soils under field conditions, and since flow rate and leachate volume can easily be adjusted, miscible displacement has great advantages for rapid reactions. Batch techniques require separation of solid and solution by centrifugation and/or filtration in which the time of separation of solid from liquid phases is not precisely known.

? Sposito, G. (1982), On the use of the Langmuir equation in the interpretation of adsorption phenomena. II. The two-surface Langmuir equation. Soil Science Society of America Journal, 46 (6), 1147-1152.

Full Text: 1982\Soi Sci Soc Ame J46, 1147.pdf

Abstract: A rigorous, mathematical representation of a sorption isotherm as a Stieltjes transform is employed to prove a theorem about the “two-surface” Langmuir equation. This theorem states that, if the distribution coefficient for an ion sorbed by a soil is a finite, decreasing function of the amount sorbed, q, and extrapolates to zero at some finite value of q, then the sorption isotherm can always be represented mathematically by a two-surface Langmuir equation. Since the proof of this theorem does not depend on the chemical mechanism of ion sorption, it follows that the adjustable parameters in the two-surface Langmuir equation cannot be interpreted in terms of surface reactions without additional, independent evidence that only adsorption on two kinds of surface site actually is involved in the ion sorption reaction.

Notes: highly cited

? Harter, R.D. (1983), Effect of soil pH on adsorption of lead, copper, zinc, and nickel. Soil Science Society of America Journal, 47 (1), 47-51.

Full Text: 1983\Soi Sci Soc Ame J47, 47.pdf

Abstract: Lead, copper, nickel, and zinc adsorption by and desorption from pH-adjusted soils has been studied. Surface and subsurface horizon samples of two soils were equilibrated with varying amounts of Ca(OH)₂ prior to metal addition. The amount of all four metals retained was dependent upon pH of the soil sample, with retention dramatically increasing above pH 7.0 to 7.5. With the exception of Ni, at least 70 to 75% of the retained metal was extractable in 0.01N HCl. Nickel was somewhat less extractable, with that sorbed by the highest pH soils being the least extractable. Based on subsequent extractability, the soils used appeared to have specific adsorption sites for Pb, Ni, and Cu but little or none for Zn. These studies cast some doubt on the concept of pH management for immobilizing heavy metals placed on the land in that sorbed metals were substantially extractable by 0.01M HCl, which has been used to estimate plant availability of soil ions.

Sharpley, A.N. (1983), Effect of soil properties on the kinetics of phosphorus desorption. Soil Science Society of America Journal, 47 (3), 462-467.

Full Text: 1983\Soi Sci Soc Ame J47, 462.pdf

Abstract: Relationships between the constants of a semilogarithmic modified Elovich and a logarithmic equation describing the kinetics of soil P desorption and physical and chemical properties of 60 soils, collected from throughout the USA, and volcanic ash were investigated. These relationships are needed for application of the equations to modeling soluble P transport in runoff from agricultural watersheds. The constants of the semilogarithmic equation (a and b) were significantly related to the extractable Al and CaCO₃ content of acidic and basic calcareous soils, respectively. For the logarithmic equation, constants (K, , and ß) were related to the ratio of Fe^- or clay-organic C content of the acidic soils and CaCO₃^- or clay-organic C content of the basic calcareous soils. It is suggested that these ratios represent an index of interactive specific surface area involved with P adsorption-desorption for a given soil. In contrast to the logarithmic equation, constants of the modified Elovich equation varied with soil P status and water-to-soil ratio. Thus, the former equation may have a wide application to describing soil P desorption in water quality models.

Martin, H.W. and Sparks, D.L. (1983), Kinetics of nonexchangeable potassium release from two coastal plain soils. Soil Science Society of America Journal, 47 (5), 883-887.

Full Text: 1983\Soi Sci Soc Ame J47, 883.pdf

Abstract: The kinetics of nonexchangeable-K release using H-saturated resin were investigated on Kalmia (fine-loamy, siliceous, thermic Typic Hapludults) and Kennansville (loamy, siliceous, thermic Arenic Hapludults) soil profiles from the Coastal Plain of Delaware. Calciumsaturated soil samples were equilibrated with H-saturated resin from 0.5 to 960 h. Equilibrium in K release in both soil profiles was attained in about 960 h. The kinetics of K release were evaluated using the Elovich, parabolic diffusion law, first-order diffusion, and zero-order equations. The first-order diffusion equation described the K-release kinetics best as evidenced by the highest correlation coefficient (r) and the lowest value of the standard error of the estimate (SE). The parabolic diffusion law also described the data satisfactorily indicating diffusion-controlled exchange. The zero-order and Elovich equations did not describe the data well as shown by higher SE values than those found with the first-order diffusion and parabolic diffusion law equations. Nonexchangeable-K release rate coefficients (k2) ranged from 1.20 to 2.210–3 h^–1 in the Kalmia soil and from 1.5 to 2.910^–3 h^–1 in the Kennansville soil. The magnitude of the k2 values suggested low rates of nonexchangeable-K release from the two soils.

? Ratnerzohar, Y., Banin, A. and Chen, Y. (1983), Oven drying as a pretreatment for surface-area determinations of soils and clays. Soil Science Society of America Journal, 47 (5), 1056-1058.

Full Text: 1983\Soi Sci Soc Ame J47, 1056.pdf

Abstract: Various procedures for drying soil and clay samples prior to surface area determination have been compared. The study was conducted on various soils—kaolinite, illite, and a number of minerals representing the smectite group. This research showed that 24 h of oven drying rather than P₂O₅ drying can be applied as a pretreatment for surface-area determinations of soils and clays by the ethylene glycol monoethyl ether (EGME) method with the exception of illite and illitic soils. Surface-area determinations following the two drying procedures were highly significantly correlated (at the 1% level) for smectites and soils, exhibiting coefficients of 0.996 and 0.986, respectively, between the oven- vs. P₂O₅ drying. Oven drying results in a 15% decrease in surface area of illite, suggesting that this procedure would not be recommended as a pretreatment for measurements on soils rich in illites. The oven drying procedure saves 4 to 5 d of the surface-area determination procedure and is applicable to smectites and soils rich in montmorillonite and kaolinite.

Jardine, P.M. and Sparks, D.L. (1984), Potassium-calcium exchange in a multireactive soil system: I. Kinetics. Soil Science Society of America Journal,