Title: Soil Science Society of America Proceedings

Title: Soil Science Society of America Proceedings

Soil Science Society of America Journal 1976-2000

Proceedings - Soil Science Society of America 1936-1975

Bulletin of the American Soil Survey Association 1921-1936

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? McAuliffe, C.D., Hall, N.S., Dean, L.A. and Hendricks, S.B. (1948), Exchange reactions between phosphate and soil: Hydroxylic surfaces of soil materials. Soil Science Society of America Proceedings, 12 (C), 119-123.

Full Text: -1959\Soi Sci Soc Ame Pro12, 119.pdf

? Dawson, J.E., Danielson, R.E. and Cameron, D.M. (1950), A study of the exchange of calcium for hydrogen in wood peat by activity methods. Soil Science Society of America Proceedings, 15 (C), 292-297.

Full Text: -1959\Soi Sci Soc Ame Pro15, 292.pdf

de Mumbrum, L.E. and Jackson, M.L. (1956), Infrared absorption evidence on exchange reaction mechanism of copper and zinc with layer silicate clays and peat. Soil Science Society of America Proceedings, 20 (3), 334-337.

Full Text: -1959\Soi Sci Soc Ame Pro20, 334.pdf

Abstract: The degree to which cations which form weak bases are sorbed in excess of cations which form strong bases is shown to be about 10% in montmorillonite and 40% in peat. These excesses were accounted for by a special reaction mechanism which was revealed when layer silicate clays or peat fractions were examined by an infrared absorption technique. Copper and zinc saturation decreased the 2.8 micron hydroxyl absorption intensity of montmorillonite, vermiculite, and kaolinite, indicating a reaction with octahedral OH in the layer silicates. The larger OH peak of kaolinite at 2.7 microns was not affected. Also, the copper treatment yielded an additional pair of absorption peaks at 6.4 and 7.0 microns. Aluminum and iron treatment tended to increase the 2.8 micron peak slightly. Copper and zinc saturation of peat fractions resulted in numerous shifts in the double bond region of the spectrum, which were indicative of chelation with C = O and N = O groups.

? Frederick, L.R. (1956), The formation of nitrate from ammonium nitrogen in soils. I. Effect of temperature. Soil Science Society of America Proceedings, 20 (4), 496-500.

Full Text: -1959\Soi Sci Soc Ame Pro20, 496.pdf

Abstract: The quantitative relationship between temperature and nitrification rates was determined in four different soils under laboratory conditions. The formation of nitrates took place at all temperatures studied between 2 and 35° C. when other factors were favorable. The rate of nitrification increased with temperature with the greatest increase between 7 and 15° C.

In Genesee silt loam (pH 7.7) nitrate nitrogen was formed at rates of 2, 10, 45, 60, 90, and 120 ppm. per week at 2, 7, 15.5, 21, 27, and 35° C., respectively, until the 200 ppm. ammonium nitrogen (NH4 -N) added was oxidized. The maximum rate in the Mellott C horizon (pH 7.8) was nearly equal to that achieved in the Genesee; the rate in the Chalmers silty clay loam (pH 6.2) was intermediate; the slowest rates found occurred in the Clermont silt loam (pH 5.0) which had maximum rates of 0, 0, 25, 30, 30, and 15 ppm. per week at the temperatures from 2 to 35° C. given above. The initial rate in the Mellott C and Clermont was much slower than the maximum rate. After 4 weeks the rate decreased in the Chalmers and Clermont, probably due to increased acidity.

A marked decrease in the rate of nitrification occurred as the pH dropped below neutrality. Change of pH by adding calcium carbonate did not change the temperature range of nitrification in Clermont silt loam. Differences in temperature range existed between the soils as well as differences in the rate of nitrification.

Temperatures fluctuating in a 24-hour cycle generally resulted in an increased rate of nitrification at temperatures below 15.5° C. and a decreased rate above 15.5° C. in Genesee silt loam.

? Sabey, B.R., Bartholomew, W.V., Shaw, R. and Pesek, J. (1956), Influence of temperature on nitrification in soils. Soil Science Society of America Proceedings, 20 (3), 357-360.

Full Text: -1959\Soi Sci Soc Ame Pro20, 357.pdf

Abstract: Nitrification of ammonium sulfate as influenced by temperature was studied in 3 Iowa soils in the laboratory and in 1 soil under field conditions over a fall and winter season. Laboratory temperatures ranged from 8° to 30° C. and soil temperature in the field varied from freezing to about 20° C.

General relationships were established between temperatures and nitrification rates in given soils. Nitrification rate decreased with diminution in soil temperature; however, the relationship was not linear over the entire temperature range. At given temperatures, ammonia oxidation rates differed between soils studied, but the temperature-nitrification rate curves for the 3 soils were similar and differed only by a constant factor.

Of particular importance to this study was the influence exerted on nitrification by temperature as it decreased from optimum to critically low temperatures. Complete inhibition was not attained until soil temperatures approached the freezing point. Only slight oxidation of ammonium occurred, however, under field conditions in soils that were fertilized after soil temperatures had decreased below 50° F.

? Mortland, M.M. (1958), Kinetics of potassium release from biotite. Soil Science Society of America Proceedings, 22 (6), 503-508.

Full Text: -1959\Soi Sci Soc Ame Pro22, 503.pdf

Abstract: Data presented suggest that the rate of K release from biotite by leaching with NaCl is independent of the amount of K in the mineral during the depletion of a large proportion of the total K content. Optical and X-ray diffraction data show that weathering of biotite to vermiculite proceeds from the outside edge in toward the center of the particle. The 14Å. layers were found to have about 4 times the diffraction intensity of the 10Å. layers. Observation was made of the actual weathering front. The dependence of rate of K release on leaching rate, NaCl concentration, temperature, time, and particle size was evaluated and an empirical equation derived relating these variables. A theory is presented that the apparent zero-order type of reaction results from the maintenance of a constant concentration of reactive K similar to the principle of a saturated solution of a material in equilibrium with its solid phase. The logarithmic portion of the curve is suggested as the place where a “saturated solution” of reactive K can no longer be maintained and rate of release becomes dependent on the amount of unreacted K.

Mortland, M.M. and Ellis, B. (1959), Realease of fixed potassium as a diffusion controlled process. Soil Science Society of America Proceedings, 23 (5), 363-364.

Full Text: -1959\Soi Sci Soc Ame Pro23, 363.pdf

Abstract: Rate of release of fixed K from vermiculite with 0.1N NaCl was studied to attempt to characterize the ratelimiting process. Of the processes considered, film diffusion satisfied most criteria as rate limiting. The activation energy of the release of K by 0.1N NaCl in the system studied was about 3,550 cal./mole, a value of the order frequently obtained for diffusion processes.

Burns, A.F. and Barber, S.A. (1961), The effect of temperature and moisture on exchangeable potassium. Soil Science Society of America Proceedings, 25 (5), 349-352.

Full Text: 1960-80\Soi Sci Soc Ame Pro25, 349.pdf

Abstract: The influence of temperature and moisture on the release of nonexchangeable K to the exchangeable form was studied in the laboratory. Varying moisture from 60 to 100% of moisture equivalent was found to have no effect on the release of nonexchangeable K at temperatures from 1° to 80° C. Temperature caused increases in the level of exchangeable K in all but one case. The higher the temperature, the greater was the rate of release of nonexchangeable K.

The first release of K appeared to conform to a first-order reaction, while subsequent release was of a zero-order nature. Activation energies were determined from data obtained by the incubation of soils at three temperatures. These values were in the range of 11,000 to 26,000 cal. per mole.

Data obtained by oven-drying soils before and after incubation at 118° C. indicate that the increases in exchangeable K obtained by these two methods were due to different reactions.

? Reed, M. and Scott, A.D. (1962), Kinetics of potassium release from biotite and mscovite in sodium tetraphenylboron solutions. Soil Science Society of America Proceedings, 26 (5), 437-440.

Full Text: 1960-80\Soi Sci Soc Ame Pro26, 437.pdf

Abstract: A mathematical expression that describes the release of interlayer K from mica particles in NaCl-NaTPB solutions was derived. The mica particles were assumed to be circular discs and the rate determining process for the release of K was considered to be the simultaneous diffusion of K and Na within the particle. Therefore, this derivation involved the solution of a two-dimensional radial diffusion problem in which K diffuses from a receding weathering front to the periphery of the particle.

The validity of these assumptions and the resulting expression was evaluated with experimentally determined K release data. The experimental data were obtained with different size fractions of biotite and muscovite placed in NaCl-NaTPB solutions for different periods of time. The results obtained with each size fraction were accurately described by the theoretical expression. In the case of a 50 to 62µ biotite fraction, this was true even though 90% of the K was released in a period of 113 hours. On the other hand, the expression did not account for the effect of particle size. A modification of the expression, based on the experimental results, however, accounted for the effects of both time and particle size.

Sawhney, B.L. (1966), Kinetics of cesium sorption by clay minerals. Soil Science Society of America Proceedings, 30 (5), 565-569.

Full Text: S\Soi Sci Soc Ame Pro30, 565.pdf; 1960-80\Soi Sci Soc Ame Pro30, 565.pdf

Abstract: Time course and the processes in the sorption of cesium from dilute solutions by illite, montmorillonite and vermiculite saturated with Ca or K and in the absence of excess saturating cation were investigated.

Cesium sorbed by illite and montmorillonite quickly reached an approximate equilibrium; the Cs sorbed by montmorillonite did not change with time while the Cs sorbed by illite changed only slightly. On the other hand, the Cs sorbed by vermiculite did not reach an equilibrium even after 500 hr. Cesium sorbed by Ca-vermiculite continued to increase while the Cs sorbed by K-vermiculite decreased.

Since the sorption of Cs by illite is limited to the external planar surfaces and interlattice edges only, equilibrium is quickly reached. Equilibrium in montmorillonite is attributed to its expanded lattice which makes all exchange sites equally available and permits exchange readily. The increased Cs sorption by Ca-vermiculite, on the other hand, is attributed to the different sorption rates by different exchange sites: initial fast sorption on external surfaces and edges followed by slow diffusion into the interlayers. The decreased Cs sorption by K-vermiculite is perhaps associated with the collapse of the partially hydrated vermiculite in suspension to 10A.

? Klobe, W.D. and Gast, R.G. (1967), Reaction affecting cation exchange kinetics in vermiculite. Soil Science Society of America Proceedings, 31 (6), 744-749.

Full Text: 1960-80\Soi Sci Soc Ame Pro31, 744.pdf

Abstract: Strong retention of cations, commonly referred to as fixation, was studied using Cs and Sr exchange reactions with Montana vermiculite. Fixation was defined as the property of an exchanger to retain cations in a state such that they are not available for rapid isotopic exchange in a well-stirred system. Efforts were directed toward qualitatively determining some of the conditions under which fixation occurs.

Equations were derived to calculate fixation using isotopic equilibrium values attained with separate aliquots of carrier-free isotope. Cesium fixation occurred in all size fractions of vermiculite ranging from 40–20 mesh through < 0.2 µ upon addition of 1 symmetry stable CsCl. The amount of 134Cs fixed at this Cs level depended on the sequence of adding separate aliquots of isotope and the corresponding stable salt, and appeared to be caused by lattice collapse.

The amount of Cs fixed increased with increasing additions of CsCl. However, when Cs saturation of the vermiculite exchange capacity exceeded 4.5%, the fraction of sorbed Cs that became fixed was relatively constant. A plot of Cs fixation vs. percent Cs saturation of the exchange capacity indicated that fixation was independent of time over an interval of 4 months.

In contrast to the Cs results, Sr was always readily exchangeable, with no evidence of lattice collapse.

? Sims, J.R. and Binghjam, F.T. (1968), Retention of borom by layer silicates, sesquioxides and soil materials: II. Sesquioxides. Soil Science Society of America Proceedings, 32 (3), 364-369.

Full Text: 1960-80\Soi Sci Soc Ame Pro32, 364.pdf

Abstract: Boron retention by hydroxy iron and aluminum materials was found to be pH dependent with maximum retention occurring in the alkaline range. The hydroxy aluminum materials retained B in amounts that were an order of magnitude greater than the amounts retained by the hydroxy iron materials. Boron retention by these materials was significantly reduced by aging on a steam bath prior to being treated with B.

Iron and aluminum were precipitated from solutions in the presence of B in application of the “mole ratio” method of determining the formulas of complexes. Evidence was obtained indicating Fe(III) or Al(III) and B were precipitated in stoichiometric proportions. Considering these precipitated forms as “solid complexes” with the general formula, MXn, a greater variety of complexes was found in the Al(III) systems than in the Fe(III) systems. In the Fe(III)-B systems, values of n for the most part were ≤1.0; in the Al(III)-B systems, values of n were ≥1.0.

Samples of similar constitution to those used in the “mole ratio” study were prepared for each metal at three pH levels. The amount of B combined in the precipitate was determined as a function of aging. The amount of B combined in the precipitate of the pH 6 samples remained relatively unchanged throughout the course of the 42-day aging period whereas the amount of B combined in the pH 9, 10, and 11 samples decreased with time. Since the observed decreases in the amounts of B combined in the precipitates were limited to the pH 9, 10, and 11 samples, it was concluded that the ready source of hydroxyl ion in these suspensions promoted hydrolysis of the hydroxy iron and aluminum precipitates, resulting in expulsion of B from the precipitates probably as borate ions.

? Hanawalt, R.B. (1969), Environmental factors influencing sorption of atmospheric ammonia by soils. Soil Science Society of America Proceedings, 33 (2), 231-234.

Full Text: 1960-80\Soi Sci Soc Ame Pro33, 231.pdf

Abstract: Under conditions of controlled temperature and atmospheric ammonia concentration, the sorption rate for atmospheric ammonia by six soils from New Jersey decreased only slightly over exposure periods up to 4 days and averaged 55 to 74 kg of NH3-N/ha/year. The ammonia sorption rate for these soils increased rapidly with increasing ammonia concentration and moderately with increasing temperature. Calculated energies of activation suggest that sorbed ammonia is held by chemical bonds rather than by physical adsorption. Increasing the velocity of gas flow across the soil surface brings more ammonia into contact with the soil and thus enhances the sorption rate. Soils sorb significant amounts of ammonia from the atmosphere which under some environmental conditions may constitute a major mechanism in the transfer of nitrogen form the atmosphere to soils.

? Malcom, R.L. and Kennedy, V.C. (1969), Rate of cation exchange on clay minerals as determined by specificion electrode techniques. Soil Science Society of America Proceedings, 33 (2), 247-253.

Full Text: 1960-80\Soi Sci Soc Ame Pro33, 247.pdf

Abstract: A cationic electrode (used as a potassium specific-ion electrode and a sodium specific-ion electrode were used to measure rates of cation exchange on clay minerals. The Ba-K exchange rates for kaolinite, illite, and montmorillonite were rapid with >75% exchange being measured within 3 sec. Because this time interval represents response time of the specific-ion electrode, the Ba-K exchange on these clay minerals occurs at a faster rate than this and may be an instantaneous process. Ba-K exchange on vermiculitic materials was characterized by both a rapid and a slow rate of exchange. A major part of the Ba-K exchange in silt- and clay-size vermiculite was found to be diffusion controlled.

Ca-K, Mg-K, Ca-Na, and Mg-Na exchange rates were rapid for all vermiculites and other clay minerals used in the experiment. Only Poole vermiculite exhibited two rates of Ba-Na exchange similar to those shown by all vermiculites during Ba-K exchange. Ba-Na exchange rates on all vermiculites except Poole were rapid.

? Green, R.E. and Yamane, V.K. (1970), Precision in pesticide adsorption measurements. Soil Science Society of America Proceedings, 34 (2), 353-355.

Full Text: 1960-80\Soi Sci Soc Ame Pro34, 353.pdf

Abstract: The precision of solute adsorption measurements (based on change of concentration in a solution equilibrated with an adsorbent) depends upon the magnitude of the solution concentration change. Coefficients of variation for measurements of atrazine adsorption on soil were inversely related to the amount adsorbed. Such variation in precision is the consequence of the indirect method of determination rather than variable experimental technique. Unsatisfactory precision is common in adsorption measurements; improvement can sometimes be achieved by altering the soil:solution ratio to obtain larger concentration changes.

Keywords: Adsorption

? Rhoades, J.D., Ingvalson, R.D. and Hatcher, J.L. (1970), Adsorption of boron by ferromagnesian minerals and magnesium hydroxide. Soil Science Society of America Proceedings, 34 (6), 938-941.

Full Text: 1960-80\Soi Sci Soc Ame Pro34, 938.pdf

Abstract: Arid-zone soils are found to have appreciable boron-sorption capacities in their silt and sand fractions. The site of this sorption is hypothesized to be magnesium-hydroxy clusters and coatings that exist on the weathering surfaces of ferromagnesian minerals such as olivine, enstatite, diopside, augite, tremolite, and hornblende as well as micaceous layer-silicate minerals.

? Green, R.E. and Corey, J.C. (1971), Pesticide adsorption measurement by flow equilibration and subsequent displacement. Soil Science Society of America Proceedings, 35 (4), 561-565.

Full Text: 1960-80\Soi Sci Soc Ame Pro35, 561.pdf

Abstract: Adsorption of pesticides from solution was measured by continuous-flow equilibration and subsequent displacement from the soil by organic solvents. This new method and the conventional batch-equilibration method gave similar results for adsorption of diuron and atrazine on three surface soils. The flow method gave superior precision to the batch method on the subsoils studied. The new procedure is well adapted to studies of adsorption reversibility and also has the advantage of limited destruction of soil aggregates during equilibration.

Keywords: Adsorption

? Leenheer, J.A. and Ahlrichs, J.L. (1971), Kinetic and equilibrium study of adsorption of carbaryl and parathion upon soil organic matter surfaces. Soil Science Society of America Proceedings, 35 (5), 700-705.

Full Text: 1960-80\Soi Sci Soc Ame Pro35, 700.pdf

Abstract: Insight into the mechanisms of carbaryl (1-Napthyl-IV-methyl carbamate) and parathion (O, O-Diethyl-o-p-nitrophenylphosphorothioate) adsorption upon organic matter derived from the Romney silty clay loam, Zanesville silt loam, and Carlisle muck soils was obtained by twofold kinetic and equilibrium study of adsorption in nonflow aqueous systems. The differences in adsorptive characteristics of the various types of organic matter were small in both the kinetic and equilibrium studies, but changing the saturating cation from calcium to hydrogen greatly increased the adsorptive capacities for both insecticides. The magnitude of the adsorptive capacities was explained in terms of the magnitude of the hydrophobic natures of the insecticide adsorbates and the organic matter adsorbents.

Kinetic adsorption studies conducted at 5, 25, and 40C showed the rate to increase as the temperature increased with the magnitude of the initial rate constant being 10~4 sec -1 • The rate-limiting step was interpreted to be diffusion of the insecticide solute molecules to the surface of the adsorbent for the first 10 min of adsorption. At longer times, intraparticle diffusion of the adsorbate into the interior of the adsorbent particles was rate limiting.

? Li, W.C., Armstrong, D.E., Williams, J.D.H., Harris, R.F. and Syers, J.K. (1972), Rate and extent of inorganic phosphate exchange in lake sediments. Soil Science Society of America Proceedings, 36 (2), 279-285.

Full Text: 1960-80\Soi Sci Soc Ame Pro36, 279.pdf

Abstract: The exchangeability of sediment inorganic P was investigated by adding carrier-free 32P inorganic phosphate to steady-state lake sediment-water systems and measuring the rate and extent of 32P incorporation into the sediment phase. The effects of sediment properties (calcareous and noncalcareous), oxygen status, and addition of inorganic P on exchangeability were evaluated. Exchangeable P comprised from 19 to 43% of the total native inorganic P of the sediments investigated. Although inorganic P was released into solution in anaerobic systems due to reduction of iron from the ferric to the ferrous state, the total pool of exchangeable P (sediment phase plus in solution) was not greatly altered. Sorbed added inorganic P (equilibrated 2 weeks) showed approximately the same degree of exchangeability as native inorganic P in noncalcareous sediments but was more exchangeable in calcareous sediments. Exchangeable P exhibited exchange rates which were resolved into three separate first-order reactions by a graphical procedure. A major portion of exchangeable native sediment P (45 to 87%) participated in the rapid exchange reaction characterized by an exchange rate constant ranging from 7.4 to 46 hours^-1. These results show that a large pool of sediment inorganic P has a high potential for interaction with the overlying lake water and for biological assimilation

Notes: highly cited

? Kuo, S. and Lotse, E.G. (1972), Kinetics of phosphate adsorption by calcium carbonate and Ca-kaolinite. Soil Science Society of America Proceedings, 36 (5), 725-729.

Full Text: 1960-80\Soi Sci Soc Ame Pro36, 725.pdf

Abstract: The objective of the present investigation was to elucidate the time-dependence of phosphate adsorption by calcium carbonate and Ca-kaolinite and to suggest a mechanism of adsorption. The phosphate adsorption by calcium carbonate and Ca-kaolinite at low phosphate concentrations in solution could be described by Langmuir adsorption isotherms, indicating that a monolayer of phosphate is formed on the surface. The calculated maximum surface saturation was 25µg/g for calcium carbonate and 187µg/g for Ca-kaolinite. A second-order kinetic equation was developed which considers both the change in phosphate concentration in solution and the surface saturation of the adsorbent during the adsorption process. The rate constant of phosphate adsorption was about 30,000 times greater for calcium carbonate than for Ca-kaolinite. About 80% of the phosphate adsorption by calcium carbonate was completed within 10 sec. The variation of the second-order rate constant with phosphate concentration was different in the two systems. The rate constant decreased in the calcium carbonate-phosphate system and increased in the Ca-kaolinite-phosphate system with increasing phosphate concentration. It was suggested that phosphate ions are adsorbed by displacing coordinated water molecules and/or coordinated anions.

? Syers, J.K., Browman, M.G., Smillie, G.W. and Corey, R.B., (1973), Phosphate sorption by soils evaluated by the Langmuir adsorption equation. Soil Science Society of America Proceedings, 37 (3), 358-363.

Full Text: 1960-80\Soi Sci Soc Ame Pro37, 358.pdf

Abstract: The sorption of added inorganic phosphate (P) by three soils which varied appreciably in their ability to sorb P was evaluated using the Langmuir adsorption equation. When the sorption data were plotted according to the conventional Langmuir equation, two linear relationships were obtained, indicating the presence of two populations of sites which have a widely differing affinity for P. Previous workers have obtained a single linear Langmuir relationship over the same equilibrium P concentration range (up to 14 µg/ml). The sites in part I (straight line corresponding to lower equilibrium P concentrations) had a very much higher (between 33 and 91 times) binding energy constant (K1), determined by regression analysis, than those in part II (straight line corresponding to higher equilibrium P concentrations). Between 40 and 52% of the total adsorption maxima was sorbed by sites in part I. A plot of the sorption data according to a rearranged form (Eadie-Hofstee plot) of the Langmuir equation gave a curve which could not be resolved satisfactorily into two straight-line components, suggesting the existence of three populations of sites. The rearranged form of the Langmuir equation was found to be preferable for evaluating P sorption at low equilibrium P concentrations. Predictions, based on the addition of high levels of added P, of the interrelationships between sorbed P and equilibrium P concentrations typical of the soil solution and soil-water systems, such as runoff, may be in error because of the failure to consider the existence of sites with appreciably higher K1 values than those which sustain relatively high concentrations of inorganic P in solution.

Keywords: Soils, Adsorption, Phosphates

? Hornsby, A.G. and Davidson, J.M. (1973), Solution and adsorbed fluometuron concentration distribution in a water-saturated soil: Experimental and predicted evaluation. Soil Science Society of America Proceedings, 37 (6), 823-828.

Full Text: 1960-80\Soi Sci Soc Ame Pro37, 823.pdf

Abstract: A technique is described for measuring the solution and adsorbed phases of fluometeron in water-saturated soil columns. The data reveal that at an average pore-water velocity of 5.5 cm/hour, the solution and adsorbed phases of fluometuron are not in equilibrium, whereas, at the 0.59 cm/hour velocity they were in equilibrium. The kinetic rate equations for adsorption and desorption were not significantly better than the equilibrium model when describing the fast displacement of fluometuron through soils. The desorption distribution coefficient (θk_A’/ρk_D’) was found to be a function of the maximum amount of herbicide adsorbed prior to desorption. The experimental data were reasonably well described by the mathematical model.

Biggar, J.W. and Cheung, M.W. (1973), Adsorption of picloram (4-amino-3,5,6-trichloropicolinic acid) on panoche, ephrata, and palouse soils: A thermodynamic approach to the adsorption mechanism. Soil Science Society of America Proceedings, 37 (6), 863-868.

Full Text: S\Soi Sci Soc Ame Pro37, 863.pdf; 1960-80\Soi Sci Soc Ame Pro37, 863.pdf

Absract: The adsorption of picloram (4-amino-3,5,6-trichloropicolinic acid) was studied on Panoche clay loam (at pH 4.2 and 1.2), Ephrata sandy loam, and Palouse silty loam. The adsorption processes could be described by the Freundlich equation with Freundlich constants, K, 1/n, and percentage of adsorption at 25C: respectively, 0.210, 0.92, and 3–5.6% for Panoche at pH 4.2; 2.5, 0.93, and 30% for Panoche at pH 1.2; 0.172, 0.99, and 1.9–3.6% for Ephrata; and 1.74, 0.92, and 26–33% for Palouse. Also evaluated were the standard free energy, entropy, and enthalpy associated with the adsorption processes. The values of ΔG° (kcal/mol), ΔS° (cal/mol per degree), and ΔH° (kcal/mol) were: respectively, −1.2±0.1, −14±2, and −5.3±0.6 for Panoche at pH 4.2; −2.98±0.05, −59±2, and −20±1 for Panoche at pH 1.2; −1.80±0.06, −24±3, and −9±1 for Ephrata; and −3.11±0.05, −3.3±1.5, and −4.1±0.4 for Palouse. Thermodynamic parameters were useful in assigning adsorption mechanisms to the four picloram-adsorbent-water systems.

Griffin, R.A. and Jurinak, J.J. (1973), Test of a new model for the kinetics of adsorption-desorption processes. Soil Science Society of America Proceedings, 37 (6), 869-872.

Full Text: 1960-80\Soi Sci Soc Ame Pro37, 869.pdf

Absract: A new model for the kinetics of adsorption-desorption processes proposed by Lindstrom, Haque, and Coshow (1970) was tested with adsorption and desorption data for the interaction of phosphate with the calcite mineral surface. The model was found to offer considerable advantages in speed and convenience to those users whose experimental conditions correspond to the assumptions inherent in the derivation of the model. There was reasonable agreement between the predicted adsorption kinetic parameters and experimental data. However, considerable disparity was observed between predicted and experimental desorption parameters. It was concluded that the model was not valid for endothermic processes.

? Kuo, S. and Loyse, E.G. (1974), Kinetics of the phosphate adsorption by lake sediments. Soil Science Society of America Proceedings, 38 (1), 50-54.

Full Text: 1960-80\Soi Sci Soc Ame Pro38, 50.pdf

Abstract: The objectives of the present investigation were to gain information on the rate and extent of phosphate adsorption and desorption and the energy of phosphate adsorption by lake sediments, and to evaluate the influence of the sediments on the phosphorus status of lake waters. While phosphate adsorption by sediments from Sebasticook Lake, Maine, could be described by the Freundlich equation over a large phosphorus concentration range, the Langmuir equation provided a good fit to the experimental data only at low phosphorus concentrations. The deviation from the Langmuir isotherm at high phosphorus concentrations was explained by an increase in total negative potential of the surface due to phosphorus adsorption and increased interaction between adsorbate molecules. The rate of phosphorus adsorption by the sediments could be described by the equation X = KC0t1/m. The calculated activation energy was 2.7 kcal/mole.

The desorption of phosphorus from minerals and sediments was dependent on the anionic species present in the solution. The replacing power of the anions appeared to be related to their ionic potential and complexing ability. The rate of phosphorus desorption could be described by the proposed kinetic equation.

? Griffin, R.A. and Jurinak, J.J. (1974), Kinetics of the phosphate interaction with calcite. Soil Science Society of America Proceedings, 38 (1), 75-79.

Full Text: 1960-80\Soi Sci Soc Ame Pro38, 75.pdf

Abstract: The kinetics of the phosphate interaction with calcite were studied. The results showed that the reaction did not proceed in the absence of the calcite surface. The kinetics of interaction could be described by two simultaneous reactions. The first reaction was second-order and was ascribed to the adsorption of phosphate on the calcite surface. The second reaction was first-order and was considered to be associated with the surface arrangement of phosphate clusters into calcium phosphate heteronuclei.

Solubility criteria were used to show that at low phosphate concentrations the ultimate calcium phosphate surface mineral formed was hydroxylapatite.

Desorption kinetics were studied by using an anion exchange resin technique. The desorption process could be described as two simultaneous first-order reactions. The desorption mechanism was postulated to correspond to the dissolution of a surface nucleated calcium phosphate mineral, with the second reaction step being the desorption of phosphate from the calcite surface sites.

The rate constants for adsorption and desorption were determined at four temperatures between 0C and 40C. The rate constants were used to compute the activation energies of adsorption and desorption. In addition, the thermodynamic parameters for the enthalpy of activation (ΔH†), the entropy of activation (ΔS†), and the free energy of activation (ΔG†), for both the adsorption and desorption processes were computed and discussed.

? Enfield, G.G. (1974), Rate of phosphorus sorption by five Oklahoma soils. Soil Science Society of America Proceedings, 38 (3), 404-407.

Full Text: 1960-80\Soi Sci Soc Ame Pro38, 404.pdf

Abstract: Two equations are evaluated in relation to their suitability as rate equations for phosphorus sorption by selected Oklahoma soils. The rate equation which best fits experimental data was ∂S/∂t = aCbSc where S is the sorbed concentration [mass per unit weight of the soils], C is solution concentration [mass per unit weight of the solution], t is time and a, b, and c are constants.

Skopp, J. and Warrick, A.W. (1974), A two-phase model for the miscible displacement of reactive solutes in soil. Soil Science Society of America Proceedings, 38 (4), 545-550.

Full Text: S\Soi Sci Soc Ame Pro38, 545.pdf; 1960-80\Soi Sci Soc Ame Pro38, 545.pdf

Abstract: Miscible displacement is studied by considering the flow regime to be composed of separate mobile and stationary phases. Solute transfer through the mobile phase occurs only by convection, whereas adsorption or reaction by the soil matrix is diffusion limited and occurs normal to the mobile-stationary interface. The model is unique in that a specific rate law is not assumed, but the solution is exact. Results are presented graphically as a function of two parameters which are compared with experimental results of other workers. The displacement of calcium by magnesium was more closely in agreement with theoretical predictions than was adsorption of picloram.

? Griffin, R.A. and Burau, R.G. (1974), Kinetics and equilibrium studies of boron desorption from soil. Soil Science Society of America Proceedings, 38 (6), 892-897.

Full Text: 1960-80\Soi Sci Soc Ame Pro38, 892.pdf

Abstract: Kinetics of boron desorption from soil were determined using 0.05M mannitol solutions to create pseudo first-order reaction conditions. The results showed two separate pseudo first-order reactions and one very slow reaction for which detailed kinetic treatment was not attempted. The relative amount of boron associated with the two fast reactions was independent of soil texture and of initial sample boron content.

It was postulated that the two reaction rates were due to desorption from two independent boron retention sites. It was speculated that the two fast reactions were due to desorption from hydroxy iron, magnesium, and aluminum materials in the clay fraction. The third or slowest reaction rate was probably due to diffusion of boron from the interior of clay minerals to solution phase.

Equilibrium studies showed that boron desorption followed a 2-site analog of a linear form of the 1-site Langmuir expression. Langmuir adsorption maximum values for each site corroborated those calculated from the kinetic study and supported the multisite interpretation of the kinetic data.

? Stanford, G., Vanderpol, R.A. and Dzienia, S. (1975), Denitrification rates in relation to total and extractable soil carbon. Soil Science Society of America Proceedings, 39 (2), 284-289.

Full Text: 1960-80\Soi Sci Soc Ame Pro39, 284.pdf

Abstract: Denitrification rates were studied under near-anaerobic conditions in 30 soils of diverse origin that differed widely in pH, organic C contents, and other characteristics. Soils with added NO3-N were submerged in water and containers were sealed to prevent further oxygen intake during incubation. Disappearance of NO3-N and production of NH4-N were determined at 1-day intervals or longer over a 10-day period. Since soils were not shaken during incubation, denitrification rates were influenced by diffusion of nitrate from the liquid to the soil layer. In most soils, amounts of NO3-N declined exponentially with time of incubation. Thus, under the experimental conditions, the loss of nitrate was depicted better by log NO3-N vs. time (t, hours) than ppm NO3-N vs. t. The apparent first-order rate constants (k), denoting the fractional loss of NO3-N/hour, ranged from about 0.001 to 0.04 hour-1. Correlations of k with total soil organic C and with soil “glucose-C,” extracted by boiling soils for 1 hour in 0.01M CaCl2, were highly significant. However, the extractable glucose-C (an index of readily decomposable C sources) provided a more reliable basis for predicting k than did total organic C. The regression of k on glucose C (X) for 30 soils is as follows: k = 0.188X − 0.00093, (r2 × 100 = 82%). For the corresponding regression involving total organic C, r2 × 100 = 69%. Within 24 to 48 hours, appreciable amounts of Mn appeared in solution and usually continued to increase with time. Reduced Fe did not appear until most of the NO3-N had disappeared. After 48 hours of incubation, the multiple regression of Mn (Y), in solution, on NH4-N produced (X1) and initial soil pH (X2), with associated statistics, was as follows: Y = 13.8 + 3.5X1 − 13.5X2 (R = 0.77), rY1.2 = 0.48. Values are significant at the 1% level.

? Kinniburg, D.G., Syers, J.K. and Jackson, M.L. (1975), Specific adsorption of trace amounts of calcium and strontium by hydroxides. Soil Science Society of America Proceedings, 39 (3), 464-470.

Full Text: 1960-80\Soi Sci Soc Ame Pro39, 464.pdf

Abstract: Freshly prepared Fe and Al hydrous oxide gels and the amorphous product of heating gibbsite selectively adsorbed traces of Ca and Sr from solutions containing a large excess (∼1M) of NaNO3. The fraction of the added Ca (Sr) adsorbed depended principally on the suspension pH, the amount of solid present, and to a lesser extent on the NaNO3 concentration. Significant Ca and Sr adsorption occurred on the Fe and Al gels, and heated gibbsite, at pH values below the points of zero charge (8.1, 9.4, and 8.3±0.1, respectively), indicating specific adsorption. The pH (± 0.10) at which 50% of the Ca was adsorbed (pH50) occurred at pH 7.15 for the Fe gel (0.093M Fe), 8.35 for the Al gel (0.093M Al), and 6.70 for the heated gibbsite (0.181M Al); for Sr, the pH50 values were 7.10, 9.00, and 6.45, respectively. For the Fe gel and heated gibbsite, an empirical model based on the law of mass action described the pH dependence of adsorption reasonably well and suggested that for each Ca or Sr fraction adsorbed, approximately one proton was released. Failure of the Al gel to fit this model may have resulted from its rapid aging.

? Stanford, G., Dzienia, S. and Vanderpol, R.A. (1975), Effect of temperature on denitrification rates in soil. Soil Science Society of America Proceedings, 39 (5), 867-870.

Full Text: 1960-80\Soi Sci Soc Ame Pro39, 867.pdf

Abstract: The effect of temperature on denitrification rate was studied with nine soils differing widely in organic matter content and chemical and physical characteristics. In the range of 15 to 35C, the temperature coefficient of denitrification, Q10, was approximately 2. Denitrification rates at 35 and 45C were similar. Between 10 and 5C, denitrification rate declined abruptly. The lower limit of the temperature range conforming to a Q10 of 2 was estimated to be 11C. In this study of water-logged soils sealed from the atmosphere, denitrification appeared to obey first-order kinetics.