bluuebunny/crossref_metadata_2025 huggingface dataset:
Hexadecanol in Soil—Its Locational Stability and Influence on Modulus of Rupture
Authors: Myhrman Matts A. , Evans D. D.
Published: July 2010

Modulus of rupture was reduced 65% for a sandy loam soil and 57% for a silt loam soil by addition of 0.4% (by weight) dry powdered hexadecanol. Emulsified hexadecanol, powdered commercial tallow alcohol, and smaller dosages had less effect.

Less than 2% of the 14C‐tagged hexadecanol placed in a 1‐cm thick layer of sandy soil moved under either saturated or unsaturated flow conditions. Movement probably took place in the form of small buoyant particles.
Solubility‐Temperature Effect on the Adsorption of Gamma‐ and Beta‐BHC from Aqueous and Hexane Solutions by Soil Materials
Authors: Mills A. C. , Biggar J. W.
Published: July 2010

Freundlich adsorption isotherms were obtained for gamma‐ and beta‐isomers of 1,2,3,4,5,6‐hexachlorocyclohexane adsorbed from aqueous and hexane solvents on Ca‐Staten peaty muck, Ca‐bentonite Ca‐Venado clay, and silica gel in the temperature range of 10 to 40C. Comparison of normal and “corrected” isotherms revealed a significant effect on adsorption due to the influence of temperature on solubility. The 1/n constants of the Freundlich equation increased with temperature according to the theory of dilute solutions. When the solubility effect is removed, the gamma isomer has greater adsorbability than the beta isomer, possibly because the former possesses a dipole moment whereas the latter does not. At constant solution fugacities, the gamma isomer on Staten peaty muck competed somewhat more effectively with hexane than with water.
Equilibrium Constants between both Freshly Prepared and Aged H Montmorillonites and Chloride Salt Solutions
Authors: Foscolos A. E. , Barshad I.
Published: July 2010

Freshly prepared and aged H montmorillonites were equilibrated with NaCl, KCl, MgCl2, and CaCl2 solutions of low concentrations. With freshly prepared H montmorillonites equilibrium constants were obtained. With aged H montmorillonites equilibrium constants were not obtained because the 1N KCl extracting technique did not yield the correct amount of adsorbed H+. To overcome this, a new method for determining adsorbed H+ was used. However, the measured equilibrium constants were either smaller or contradictory to those obtained with freshly prepared H montmorillonites because it was not possible to assess the exact amount of adsorbed H+ in the presence of hydroxyaluminum compounds. Thus, only equilibrium constants obtained with freshly prepared H montmorillonites were considered to be valid.
Arsenic Content of Soil and Crops Following Use of Methanearsonate Herbicides
Authors: Johnson L. R. , Hiltbold A. E.
Published: July 2010

Distribution of As with depth in soil was determined after 4 years of repeated applications of monosodium (MSMA), monoammonium (MAMA), and disodium methanearsonate (DSMA) to turf. Arsenic concentrations decreased with depth. Percentage recovery of applied As in the upper 30 cm of soil decreased with increasing application rates. Yields of cotton (Gossypium hirsutum L.), soybeans (Glycine max L. Merr.), sorghum‐sudan hybrid (Sorghum vulgare Pers. × S. sudanense (Piper) Stapf), corn (Zea mays L.), oats (Avena sativa L.), vetch (Vicia villosa Roth), and crimson clover (Trifolium incarnatum L.) were not affected by previous As treatments. Seed of cotton and soybeans accumulated more As than corn or forage from sorghum or the winter crops. Uptake of residual As was greater from MSMA than from DSMA or MAMA, and from the high rate of application than from the medium or low rates. About 90% of the soil As content occurred in the clay fraction. Much of the soil As was extracted by NH4Cl that removed little if any P. Most of the soil P was associated with iron minerals and organic matter, while As was associated with aluminum. No appreciable organic As was found.
Lanthanum and Scandium Distribution in Three Glacial Soils of Western Wisconsin
Authors: Kline J. R. , Foss J. E. , Brar S. S.
Published: July 2010

Neutron activation analysis was used to deterimne the total La and Sc content of three soils developed from loess‐capped glacial till. The profiles were classified as Gray‐Brown Podzolics (Hapludalfs) overlying paleosols developed in Rockain till. The total La content in the less than 250µ fraction of these soils ranged from 18.1 to 37.1 ppm, with an average content of 23.7 ppm in the loess and 28.5 ppm in the glacial till. Total Sc in the soils ranged from 5.1 to 10.9 ppm with average contents of 6.5 and 9.0 ppm in the loess and glacial till, respectively. Translocation by pedogenic processes was indicated by the accumulation of these elements in the argillic B horizons. Correlation coefficients of La and Sc with clay percentages in the profiles were 0.79 and 0.88, respectively.
Effect of Phosphorus Carriers and Zine Sources on Phosphorus‐Zine Interaction in Corn
Authors: Ganiron R. B. , Adriano D. C. , Paulsen G. M. , Murphy L. S.
Published: July 2010

Growth of corn (Zea mays L.) seedlings in solution cultures responded to temperature > Zn rate > P carrier > Zn source. Phosphorus accumulated in roots and shoots of Zn‐deficient seedlings at the higher temperature, but was depleted from roots when seedlings were supplied with Zn. Nearly similar Zn concentrations were usually present in roots and shoots of seedlings grown at the lower temperature, suggesting that temperature affected soil Zn availability more than uptake or translocation. Monoammonium phosphate (MAP) was slightly more favorable for growth than ammonium polyphosphate (APP), but APP increased P uptake more than MAP. Chelated Zn was a slightly more efficient source than Zn sulfate.

Phosphorus depressed corn grain yields when soil Zn levels were low. Applying Zn increased grain yields only to levels produced without P fertilization. Concentrations of P in the leaves varied inversely with the rate of Zn fertilization, but concentrations of Zn were not affected markedly by the treatments. APP and chelated Zn were only slightly better sources than MAP and Zn sulfate, respectively.
Steady Gravitational Convection Induced by a Line Source of Salt in a Soil
Authors: Raats P. A. C.
Published: July 2010

A theoretical analysis of steady gravitational convection from a line source of salt in a saturated or in a uniformly partially saturated soil is presented. The flow pattern of the water‐solute mixture and the distribution of the salt are shown to depend upon the source strength of the line source, the effective mass diffusion coefficient of the salt in the soil, the hydraulic conductivity of the soil, and a parameter describing the increase in density due to the added solute. Qualitatively, the analysis agrees with experimental observations. Theory and experiment both indicate that gravitational convection can be significant only if the hydraulic conductivity is large, which may be the case if the soil is coarse textured and the water content is not too small.
Influence of Chemical Weathering on Basal Spacings of Clay Minerals
Authors: Conyers E. S. , Wilding L. P. , McLean E. O.
Published: July 2010

Illite, vermiculite, montmorillonite, kaolinite, and a Brookston soil clay were weathered by H‐, HO‐, and H‐resin; sodium tetraphenyl‐boron + resin; and boiling 1N nitric acid + resin treatments. X‐ray diffractograms of the treated clays suggest the following effects on the mineral structures. Resin caused relatively minor changes compared to unweathered specimens. NaBPh4 removed interlayer K from 10A and 10–14A interstratified components of illite, vermiculite, and Brookston soil clay resulting in partial expansion of 10–14A components as evidenced by diffractograms of glycolated samples. HNO3 dissolved less stable components of the illite specimen and/or favored preferred orientation of aggregates as indicated by marked increases in the intensity of mica basal reflections. Estimations of K content of mica from 10:5A peak‐intensity and area ratios indicated that mica remnants in acid‐treated illite were lower in K than those in unweathered or NaBPh4‐treated illite. Treatment with HNO3 severely altered the expansibility of vermiculite, transforming a part of the specimen into an expanding lattice structure and dissolving much of the remainder. The 10A and 14A components of Brookston soil clay were less altered by HNO3 treatment; however, the 17–18A peak in the glycolated sample was sharper, and thermally stable interlayer components were less evident after acid treatment. HNO3‐ and NaBPh4‐treated kaolinite and montmorillonite basal spacings remained essentially the same as untreated samples. These data are evaluated in terms of mechanisms of K‐release from the weathered clays and subsequent K‐content found in soybean plants (Glycine max L.) grown in the clay residues.
On the Interaction of Water Molecules and Montmorillonite Surfaces
Authors: Kijne J. W.
Published: July 2010

The adsorption of water was studied on monoionic montmorillonite saturated with Cs, Rb, Li, Na, NH4, and Ca ions. These ions vary in their influence on the structure of water in solution. Thus the effect on the adsorbed water by exchange ions could be compared with the effect of these ions in solution. Heats of wetting of the montmorillonite samples were determined as a function of the equilibrium relative vapor pressure. Entropy values were calculated from the heats of wetting combined with values of the surface potential from adsorption isotherms using the Gibbs surface excess equation. The decrease in heats of wetting with increasing relative vapor pressure was discontinuous near p/po = 0.1. This was interpreted as indicating a change at the surface of the clay mineral probably related with ion hydration effects. Consequently the obtained entropy changes could not be assigned entirely to the adsorbed water molecules. At low relative vapor pressures the entropy values strongly reflected the influence of the exchange ion which was found to be similar to that exerted by these ions in solution. At higher relative vapor pressures the entropy of the system was about 4 e.u. below that of liquid water which was nearly the same as the likely value for the silicate sheet itself obtained in earlier studies.
Weathering of Montmorillonite During Formation of a Solodic Soil II. Nature of the Mixed Layer Products
Authors: Klages M. G.
Published: July 2010

The Solodic (Paleargid) soil being studied had previously been shown to have clay mineralogy similar to that of associated Chestnut (Argiustol) and Solodized‐Solonetz (Natrargid) soils. Mica and montmorillonite were the dominant clay minerals in the calcareous glacial till parent material. Montmorillonite failed to give an X‐ray diffraction peak in clays of the surface soil, yet infrared absorption, cation exchange capacity, and surface area were similar to that of the parent material. Clays of the parent material (C horizon) and surface soil (A horizon) were studied to determine mineralogical properties. Dioctahedral and trioctahedral minerals were present in both the A and C horizon with dioctahedral predominating. Quantitative estimates of mineral composition were made on the basis of infrared absorption, total potassium, and cation exchange properties. These showed kaolinite, quartz, chlorite, vermiculite, and allophane to be present in addition to mica and montmorillonite. Differences in clay mineral content from the parent material to the surface soil were minor. It was concluded that the most important effect of soil formation on clay mineralogy was a change from relatively pure mineral crystals to particles with several 2:1 minerals in a highly random arrangement of various degrees of interlayer expansion.
Kinetics of the Formation and Breakdown of Ca‐Montmorillonite Tactoids
Authors: Shainberg I. , Kaiserman A.
Published: July 2010

The kinetics of Ca‐montmorillonite tactoid formation and breakdown was followed by recording the changes in light transmission as a function of time when Ca‐montmorillonite suspensions of 0.05% (w/v) concentration were added to Na‐montmorillonite suspensions of the same concentration in a titrating vessel placed in the light path of a spectrophotometer. Tactoid formation was found to be instantaneous whereas the breakdown of Ca tactoids took about 10 min. It was suggested that the initial step upon mixing sodium and calcium montmorillonite was the redistribution of adsorbed ions. For tactoids to break, ions have to interdiffuse into the tactoids. Since the mobility of ions adsorbed on the internal surfaces is low, tactoid breakdown is slow. Ion diffusion on the single platelets of Na clay and the external surfaces of the tactoids is high; thus the formation of tactoids is instantaneous.
The Prediction of Evaporation, Drainage, and Soil Water Storage for a Bare Soil
Authors: Black T. A. , Gardner W. R. , Thurtell G. W.
Published: July 2010

Evaporation, drainage, and changes in storage for a bare Plainfield sand were measured with a lysimeter during June, July, and August 1967, under natural rainfall conditions. Cumulative evaporation at any stage was proportional to the square root of time following each heavy rainfall. The drainage rate was found to be an exponential function of water storage. Both relations can be predicted from flow theory with knowledge of soil capillary conductivity, diffusivity, and moisture retention characteristics. Using these two relations and daily rainfall data, the water storage in the top 150 cm was predicted over the season to within 0.3 cm.
Standard Heats and Entropies of Exchange for Alkali Metal Cations on Wyoming Bentonite
Authors: Gast R. G. , Van Bladel Robert , Deshpande K. B.
Published: July 2010

Standard heats of exchange, ΔH°, were determined for alkali metal cation exchange on Wyoming bentonite using a Calvet microcalorimeter. In addition, values of ΔH° for Na‐Cs, Na‐Rb, and Cs‐Rb exchange were evaluated from selectivity measurements conducted at 25 and 50C. Standard entropies of exchange, ΔS°, were calculated by combining the standard heats with free energy values, ΔG°, estimated from equilibrium selectivity coefficient determinations using the relationship ΔG° = ΔH° − TΔS°. Values of ΔH° varied from +150 cal mole‐1 for Na→Li exchange to −2,557 cal mole‐1 for Na→Cs exchange. Values of ΔG° ranged from +48 to −1,081 cal mole‐1 for these reactions giving values of ΔS° ranging from +0.5 to −4.9 cal mole‐1 deg.‐1. Both ΔH° and ΔS° were always negative for uptake of the preferred cation with the absolute values increasing with the degree of selectivity. While the entropy changes did contribute significantly to the standard free energies of exchange, they were only about 10% of the hydration entropy differences for Na‐Li and Na‐K exchange and 26 and 41% for Na‐Rb and Na‐Cs exchange, respectively.
Theoretical Consideration of the Calcium Sulfate‐Bicarbonate‐Carbonate Interrelation in Soil Solution
Authors: Nakayama F. S.
Published: July 2010

The probable distributions of the ion‐pairs CaSO4° and CaCO3°, and complex CaHCO3+ in solution are discussed thermodynamically and graphically in terms of SO42‐, CO32‐, HCO3‐, and H+ activities. In alkali media where the CO32‐ form predominates, the CaCO3° species will dominate the CaSO4° and CaHCO3+ forms and is a significant part of the total calcium in solution.
Adsorption of Nitrate in Amorphous and Kaolinitic Hawaiian Soils
Authors: Singh B. R. , Kanehiro Y.
Published: July 2010

The adsorption of nitrate in an amorphous Akaka silty clay and kaolinitic Wahiawa silty clay increased consistently with increasing concentration and decreasing pH of the electrolyte solution. The magnitude of adsorption was higher in the Akaka than in the Wahiawa soil. The amount of adsorbed nitrate was notably more when SO43 rather than Cl was used as the replacing anion. It was deduced that while the concentration‐dependent NO3 adsorption is due to electrostatic and van der Waal forces, the pH‐dependent adsorption is largely due to electrostatic forces. The adsorption of nitrate followed the Freundlich type of isotherm.
Ion Selectivity of Micas as Influenced by Degree of Potassium Depletion
Authors: Le Roux J. , Rich C. I.
Published: July 2010

The Rb/Sr selectivity coefficient of muscovite and biotite reached a maximum at an intermediate degree of K‐depletion of these micas. The Rb/Sr ratio of ions absorbed from a solution, initially containing equivalent amounts of Rb and Sr, was determined for the two micas altered to different degrees to Mg‐vermiculite. X‐ray diffraction of the Rb‐Sr treated vermiculites gave nonintegral peaks for the basal reflections, indicating random interstratification of Rb and Sr + Mg saturated layers. The results support previous proposals that selective sites for K are probably situated at wedge‐shaped zones occurring at frayed edges and deeper within the altered mica particles. As K is removed from mica, the number of such wedges should first increase and then decrease. Selectivity of K and other large monovalent ions should also follow this same trend.
Reduction of Sulfate to Sulfide in Waterlogged Soil
Authors: Connell W. E. , Patrick W. H.
Published: July 2010

A study was made of sulfate reduction to sulfide in water‐logged soils supplied with an energy source. Sulfate reduction was more rapid in surface soil than in subsurface layers with sulfide appearing 2 days after waterlogging samples of a surface soil. The amount of sulfide precipitated from added H2S in two soils was approximately equivalent to the amounts of ferrous iron released by waterlogging. Added Fe2O3 was effective in precipitating H2S. Sulfate reduction was retarded by nitrate. Addition of oxygen to highly reduced soils caused a rapid decrease in sulfide content, with one‐half of the sulfide being oxidized in 15 minutes and all the sulfide oxidized after 8 hours.
Fragipan Horizons and Be Masses in the Middle Coastal Plain of North Central North Carolina
Authors: Steele Forrest , Daniels R. B. , Gamble E. E. , Nelson L. A.
Published: July 2010

Soils with fragipan horizons are minor in areal extent but soils with friable eluviated (Be) masses are common along the 120‐ and 140‐foot contours (37‐ to 43‐m) of the Sunderland geomorphic surface between Goldsboro, N. C., and Emporia, Va. Where they occur, fragipan horizons commonly have Be masses, and in some the dense brittle materials and friable eluviated materials are intimately mixed. The morphology of fragipan horizons and horizons with Be masses are similar and it is difficult to separate them where they merge on the landscape. Brittleness is about the only feature that can be used consistently to separate fragipan horizons and horizons with Be masses. Brittleness that is produced by partial iron cementation, plinthite for example, should not be used in identification of fragipan horizons.
Properties of Some Soils in the Cumberland Plateau as Related to Slope Aspect and Position
Authors: Franzmeier D. P. , Pedersen E. J. , Longwell T. J. , Byrne J. G. , Losche C. K.
Published: July 2010

Soils developed from acid siltstones and shales were sampled on the lower, middle, and upper part of steep north and south‐facing slopes in transects made across ridges in eastern Kentucky and Tennessee. Particle size distribution, base saturation, and soil temperature are related to slope position. Soils in the middle slope positions are higher in coarse material than those in the upper or lower positions. Soils in the lower slope positions have the highest base status and are coolest.

Slope aspect influences soil temperature and organic matter content and the kinds of horizons formed and their color. Most soils on the south‐facing slopes have argillic horizons while most on the north‐facing slopes have cambic horizons. Soils on the north slope have almost 2C lower mean annual temperature, contain more organic matter, are darker in color, and hold more water during a period of water stress than soils on the south‐facing slope.
Runoff Inducement in an Arid Region by Removal of Vegetation
Authors: Tadmor N. H. , Shanan L.
Published: July 2010

Eradication of natural vegetation from runoff plots in a 250‐mm isohet region increased annual runoff threefold from 7% to 21% of annual rainfall. The vegetation cover increased the infiltration rates of the loess soil by 40–50%. A “priming” rainfall of 2–4 mm/day was required to cause runoff from both bare and vegetation areas. Interception storage of vegetation was 0.1–0.4 mm.
Effect of Soil Temperature on Nodulation of Ceanothus Velutinus Dougl.
Authors: Wollum A. G. , Youngberg C. T.
Published: July 2010

The nodulation of snowbrush (Ceanothus velutinus Dougl.) from two seed sources was evaluated at soil temperatures of 10, 15, 22, 26, and 31C. One source was from the east side of the Cascade Mountains in Oregon and one from the west side. Plants in these areas are considered distinct ecotypes. For the east ecotype it was found that more and larger nodules were formed at 26C than at any other temperature tested. However, the number and size of nodules for the west ecotype plants were not significantly different at 22 and 26C. Maximum plant yields for the east and west plants were found to occur at 26 and at 22 and 26C, respectively. Generally, the east ecotype plant required a longer period of time to form nodules than the west plants at comparable temperatures. When the natural variation of soil temperature was characterized, it was found that temperatures were below 20C about 80% of the sampling period and between 20 and 25C for less than 10% of the sampling period.
Numerical Method for Estimating Simultaneous Flow of Water and Salt in Unsaturated Soils
Authors: Bresler E. , Hanks R. J.
Published: July 2010

A numerical solution of non‐interacting salt flow simultaneously with water in unsaturated soil was devised and programmed. Solutions were obtained for infiltration, redistribution, and evaporation under different wetting and boundary conditions. The effect of diffusion on salt distribution was neglected in the computations. The method was found to give reasonable results for non‐interacting solutes. When compared with measured total salt distribution after one wetting and drying cycle, the model gave fairly good results when a source term was added to the computations. The method can be applied to some practical problems, such as leaching of salts and fertilizer movement.
Infiltration, Redistribution, and Subsequent Evaporation of Water from Soil as Affected by Wetting Rate and Hysteresis
Authors: Bresler E. , Kemper W. D. , Hanks R. J.
Published: July 2010

Soil columns were wetted at three different rates which caused unequal water content profiles during infiltration. Water content profiles during infiltration, redistribution, and evaporation were observed experimentally and computed using a numerical solution of the isothermal flow equation. Each wetting rate resulted in a different drying water retention curve. The hysteresis in soil water content‐water suction relationships had a larger influence as the wetting rate increased. Hysteresis effects tend to keep the water content higher and the zone of wetting shallower during the redistribution stage when rates of wetting are faster. Higher water content and lower wetting depth at any redistribution time caused subsequent evaporation to be greater. Evaporation was directly related to the previous wetting rate, either when the soil was subjected to evaporation immediately following infiltration or when subjected to evaporation after redistribution for 4 days. The differences in evaporation between the three wetting treatments were significant at the 99% probability level. Allowing time for redistribution decreased evaporation compared to evaporation and redistribution occurring simultaneously. The effects of wetting rates and hysteresis on water content profiles and evaporation were similar in the experimental and computed results.
Interaction Between the Humic Acid Fraction of Soils and Certain Metallic Cations
Authors: Khan S. U.
Published: July 2010

Studies were conducted to investigate the interaction between certain metallic cations and the humic acids isolated from one Black Chernozem and two Gray Wooded soils of Alberta. Potentiometric titrations of the humic acids in the presence of added cations showed the formation of metal‐humic acid complexes. The metallic cations released protons from functional groups of the humic acids and formed complexes. The order of magnitude of pH drop of the humic acids on addition of metallic cations was found to be Mn2+ < Co2+ < Ni2+ < Zn2+ < Cu2+ < Al3+ < Fe3+. The effectiveness of added cations in coagulating the humic acids followed the sequence Mn2+ < Co2+ < Ni2+ < Zn2+ < Cu2+ < Fe3+ < Al3+.
Effect of Acidity on Reactions of Organic Acids and Amines with Montmorillonitic Clay Surfaces
Authors: Harter Robert D. , Ahlrichs James L.
Published: July 2010

The effect of pH on the nature of 2,4‐D, Amiben, aniline, and urea adsorbed by montmorillonite has been characterized. In all cases the infrared spectra of air dry systems indicated a change of the compound to the acid or protonated form when the corresponding suspension pH was two to three pH units higher than the pKa of the molecule. This is consistent with previous studies which indicated that the clay surface in air dry systems is more acid than shown by electrometric pH readings of the suspension. At pH levels below the pKa the acids show evidence of adsorption by the clay. The amines acquire a positive charge and are capable of interacting with the clay exchange complex. Spectra of the aniline and urea adsorbed to acid clay were nearly identical to those of their hydrochlorides in the same environment, indicating reactions with the acid clay surfaces by protonated molecules.
Phosphatoiron (III) and Phosphatoaluminum Complexes in Dilute Solutions
Authors: Bohn H. L. , Peech Michael
Published: July 2010

The phosphate complexes of iron(III) and aluminum in dilute solutions were studied by ultraviolet spectrophotometry, voltammetry, and cation exchange resins. The stability constant of the FeH2PO42+ ion was found to be 4(± 0.8) × 103 at ionic strength of 0.1. Although phosphatoaluminum complexes were not directly detectable, their stability constants could be estimated as ≤ 103 for AlH2PO42+ and ≤ 107 for AlHPO4+. These results indicate that, over the range of ion concentrations likely to be found in soil solutions, phosphatoiron(III) complexes are the predominant phosphate species in solutions of pH < 1.3; phosphatoaluminum complexes are the predominant phosphate species in the range of pH 1.3–4.3; and aquated phosphate ions are the predominant species in the range of 4.3–7.2. Published equilibrium constants for phosphatocalcium and phosphatomagnesium complexes and ion pairs revealed that these species are the predominant phosphate species at pH > 7.2.
An Appraisal of the dai/dx Hypothesis
Authors: Olsen R. A.
Published: July 2010

An attempt was made to subject the dai/dx hypothesis to a more critical experimental appraisal than has been accomplished previously. A system was devised by the use of synthetic exchanger particles in which the suspension effect, as measured electrometrically, was exceptionally large; the value indicated an apparent difference in aRb + in the most extreme parts of the system of about one million. According to the dai/dx hypothesis, the rate of absorption of Rb+ by plant roots should have differed from these two parts of the system by a correspondingly large factor. The observed rates of absorption from all parts of the system, however, were within a factor of 1.2 of being identical. It is concluded that either: (i) electrometric methods do not provide a reliable estimation of ion activities in aqueous systems containing exchanger particles, (ii) the rate of absorption of an ion by plant roots is not a function of the activity gradient extending normal to the absorption surface, or (iii) both of these commonly accepted postulates are incorrect. The data are considered to be consistent with the alternative dμ̄i/dx hypothesis.
Retention of Zinc by Some Arid Zone Soil Materials Treated With Zinc Sulfate
Authors: Sharpless R. G. , Wallihan E. F. , Peterson F. F.
Published: July 2010

Samples from six orchard soils and 17 type‐location soils were used for laboratory study. Results showed that addition of a concentrated solution of ZnSO4 to soil resulted in rapid adsorption of Zn, about 75% of the total being accounted for by cation exchange during the first minute. Subsequent rate of conversion from exchangeable to acid extractable form varied widely among soils. The main factors that accounted for the extent of Zn retention were CEC and pH; there appeared to be no significant relation to available P.
Variation in Potassium Available to Trees Within an Outwash Soil
Authors: Hart James B. , Leaf Albert L. , Stutzbach Stephen J.
Published: July 2010

Thirteen deep soil pits were sampled by strata, 40 forest floor samples were collected, and tube samples were taken at 119 locations of the surface 15‐cm layer and at 30‐cm intervals to a soil depth of 2.1 m. The sampling was done on an 0.8‐ha area supporting good and poor growing 37‐year‐old red pine (Pinus resinosa Ait.) separated by an old fenceline. The soil has formed in slanted and discontinuous strata of different physical and chemical properties. Acid‐extractable K data from the 13 pits indicate the magnitude but not the pattern of variability. Data from the pit samples were used to predict acid‐extractable K for the tube samples. Regression techniques were used on the 0‐ to 15‐ and 15‐ to 45‐cm layers. An ocular textural classification technique was employed for deeper soil layers. Results indicate K variability is pronounced in the soil volume studied and is associated with the occurrence of discontinuous finer‐textured strata at differing depths. K variability as measured by these techniques was found to be only partly related to red pine growth.
Increased Availability of Nitrogen and Phosphorus in the Root Zone of Conifers
Authors: Fisher R. F. , Stone E. L.
Published: July 2010

The N and P contents of herbaceous vegetation and soil across the interface between pine or larch plantations and the open, abandoned fields in which they were planted were investigated. Herbaceous plants growing beneath or near the conifers had significantly higher N and P concentrations as well as greater dry weight. NO3‐N, NH3‐N, and readily soluble P were also significantly higher beneath or near the conifers. Although the total N of the forested and open soils was not different, significantly higher percentages of the organic N could be extracted with hydrofluoric acid from the soil beneath 10‐ to 14‐year‐old plantations. However, the proportion extracted from soils beneath 32‐ to 33‐year‐old plantations was not different from that extracted from adjacent old‐field soils. All lines of evidence are consistent with a hypothesis that the conifer rhizosphere mineralizes or otherwise extracts some fraction of the soil nitrogen that had been resistant to microbial action under the previous vegetation.
Nitrate Content of the Upper Rio Grande as Influenced by Nitrogen Fertilization of Adjacent Irrigated Lands
Authors: Bower C. A. , Wilcox L. V.
Published: July 2010

Over a 30‐year period, when the application of N fertilizer to three irrigated areas adjacent to the Upper Rio Grande increased from a very low to a high level, the overall NO3‐N concentration of the river did not increase, indicating no significant stream pollution by NO3‐N from applied N fertilizer.
Soil Water Evaporation as Affected by Wetting Methods and Crust Formation
Authors: Bresler E. , Kemper W. D.
Published: July 2010

Laboratory studies showed that evaporation from soil columns which were wetted by flooding was 25–30% higher than soil wetted by rain and 30–40% higher than from soil to which NaCl was applied prior to wetting by simulated rain. About 25–35% more water evaporated from soil which was exposed to evaporation immediately following infiltration compared to soil which exposed to evaporation 4 days after infiltration ceased. The crust which was formed at the soil surface by the raindrop action and dispersion due to sodium ion caused the wetting rate to decrease from 23 cm/hour in the flooded treatment to 1.1 in the rain and 0.06 cm/hour in the rain on NaCl treatment. Higher water content profile and shallower wetting zone resulted when rates of wetting were faster, and caused the total water loss to be higher. The total water loss was also affected by the type of crust which formed at the soil surface. After from 1 to 4 hours of evaporation, the highest resistance to water flow was estimated in the region immediately below the crust. This high resistance region hastened the formation of a surface dry layer in the rain‐wetted treatments which reduced evaporation.
Conductometric and Potentiometric Titration of Exchangeable Aluminum
Authors: Rich C. I.
Published: July 2010

Conductometric and potentiometric titrations of an AlCl3 solution and AlCl3‐treated Dowex‐50, trioctahedral vermiculite, and two montmorillonites were compared with the Al and acidity removed from these systems with neutral chloride salts. The endpoints of potentiometric titrations of AlCl3 or AlCl3‐treated exchangers in neutral salt solution were lowered by these salts and adsorption of partially neutralized hydroxy‐Al groups on the exchangers. Titrations of solutions to pH 8.0 gave better estimates of the acidity present than did inflection points. Hydrolysis of Al on the exchanger during exchange may produce H+ ions not originally present. Conductometric titrations with Na2B4O7 and NaOH were confounded by incomplete exchange and reaction with Al. The formation of aluminate in the titration with NaOH and Ba(OH)2 decreased the conductivity and caused “high” results. It is proposed that conductometric titrations should be continued until the change in conductivity with added base approaches that of a blank. A method for correcting for aluminate formation is proposed.
Titration of Acid Soils
Authors: Dewan H. C. , Rich C. I.
Published: July 2010

Seven acid soils containing varied cation exchange materials were studied by means of conductometric and potentiometric titrations with Ba(OH)2, NaOH, Na2B4O7, and NaOAc, and extractions with KCl, NH4OAc (pH 4.8), and BaCl2‐triethanolamine (pH 8.3).

Generally consistent results were obtained when the aluminate reaction was considered for titrations with strong bases. The extent of the aluminate reaction for exchangeable interlayer Al3+ apparently depends on the exchange of Al3+ by the base. Thus, the low values in conductometric titrations with NaOH compared to Ba(OH)2 are explained on the basis of the poorer exchange of Al3+ by Na+.

Titrations with NaOAc indicate that only a cat clay soil contained strong acid type exchangeable H+, although four of the other soils contained about 20 meq/100g of Al3+ exchangeable by KCl.
Michaelis Constant of Soil Urease
Authors: Paulson K. N. , Kurtz L. T.
Published: July 2010

Application of the Michaelis‐Menten equation to urease activity of soil showed that the Michaelis constant (Km) changed with fluctuation in microbial population and thus with changes in the proportion of microbial and adsorbed urease. Regression of urease activity on number of ureolytic microorganisms permitted division of total urease activity into portions caused by microbial and adsorbed forms, respectively. Computations using the partitioned urease activities gave Km's for the microbial and adsorbed forms of 0.057 and 0.252M, respectively. These values are similar in order of magnitude to those reported in the literature and thus further support the hypothesis that urease is active in both microbial and adsorbed forms in soil.
Early Effects of Forest Vegetation and Topographic Position on Dark‐Colored, Prairie‐Derived Soils
Authors: Geis J. W. , Boggess W. R. , Alexander J. D.
Published: July 2010

A complete development range of soils from the Humic Gley (Haplaquolls) and Brunizem (Argiudolls) soils of the original tall grass prairie to well‐developed Brunizem‐Gray‐Brown Podzolic Intergrade (Mollic and Aquollic Hapludalfs) soils was studied in a recently forested “Prairie Grove” remnant in eastcentral Illinois. The first measurable changes occur in organic carbon, cation exchange capacity, and base saturation. Alterations in color and structural development which distinguish a minimal A2 horizon are followed by accelerated movement of clay from the A to B horizons. Differences in soil development in an area of uniform forest occupancy are related to the physiographic position of the soil units and the subsequent retarding of normal forest soil development by conditions of excessive soil moisture.
Losses of Wheat Straw Residue Under Simulated Field Conditions
Authors: Brown Paul L. , Dickey David D.
Published: July 2010

Wheat (Triticum aestivum L.) straw residues contained in fiberglass screen envelopes were exposed to field conditions at Bozeman and Huntley, Mont. Samples from above‐soil, on‐soil, and buried exposures were taken periodically during an 18‐month period to measure weight losses and changes in N and P contents of the residues. Decomposition was more rapid at Huntley than at Bozeman, probably because air temperatures averaged 2.3C warmer at Huntley. Percentage losses were inversely related to residue amounts. After 18 months, on‐soil residue losses averaged 31% at Bozeman and 40% at Huntley. The 50% decomposition stage for buried straw occurred in 3 months at Huntley and 6 months at Bozeman, and after 18 months, losses of buried straw averaged 93% at Bozeman and 98% at Huntley. Compared to the original straw, both N and P percentages increased as much as sixfold in the buried samples during decomposition. For buried straw, maximum percent N was 1.18 at Bozeman and 1.46 at Huntley. Similar values for maximum percent P were 0.132 at Bozeman and 0.147 at Huntley.

For buried straw, N and P immobilization was maximum after 3 months at both locations. At that time, N contents at the two locations exceeded original content by an average of 1.6, 2.9, 2.8, 2.9, and 5.3 kg/ha for straw rates of 1,121, 2,242, 3,363, 4,484, and 6,732 kg/ha. P contents exceeded original content by an average of 0.3, 0.5, 0.7, 1.0, and 1.7 kg/ha for the same straw rates.
Fertilizer Release from Packets and its Effect on Tree Growth
Authors: Attoe O. J. , Rasson F. L. , Dahnke W. C. , Boyle J. R.
Published: July 2010

A study was made of various factors affecting the release of fertilizer from polyethylene packets. Movement of water from the soil into the packets was almost entirely in the form of vapor and was closely related to both the area and perimeter of the pinholes in the packets. Absorption of water vapor by saturated salt solutions from air maintained near 100% relative humidity was directly related to both the solubility of the salts used and to their vapor pressure lowering values. The length of time required to release the fertilizer was directly related to the size of packet and inversely related to the number of pinholes. The more soluble fertilizer constituents were released faster than the less soluble ones. The use of packets of 19‐5‐17 (N, P, K) fertilizer in the field generally increased by 10 to more than 100% the rates of growth in height and diameter of cottonwood (Populus deltoides Marsh.), silver maple (Acer saccharinum L.), sugar maple (Acer saccharum Marsh.), and white ash (Fraxinus americana L.).
Temperature Stabilization of Gamma Ray Transmission Equipment
Authors: Reginato Robert J. , Stout Karl
Published: July 2010

Accurate measurements of water content of soil in situ can now be made using an improved gamma ray transmission method. Prior to this development, existing equipment tried in the field responded to temperature fluctuations as well as density and water content changes. With the new method, the nuclear counting system is stabilized on a reference 60Co gamma ray source attached to the detector assembly. Density changes are then measured with a 137Cs gamma ray source about 30 cm away from the detector. In laboratory tests, similar attenuated count rates were obtained for 137Cs gamma rays through a standard absorber while the temperature was varied from 5 to 33C.
Salt Accumulation at the Soybean (Glycine Max. (L.) Merr.) Root‐Soil Interface
Authors: Riley D. , Barber S. A.
Published: July 2010

Water soluble salts accumulated at the soybean (Glycine max L.) root‐soil interface and in the rhizosphere soil when salts, dissolved in the soil solution, moved to the root surface at a greater rate than they were absorbed by the roots. Salt accumulation increased with increase of salt concentration in the soil solution and transpiration rate. The average salt accumulation decreased with increase in the average age of the roots.
Prediction of Interlayer Swelling of Clays in Mixed‐Salt Solutions
Authors: McNeal B. L.
Published: July 2010

A comparison has been made of the relative interlayer swelling values predicted from two different ion‐distribution models for mixed Na‐, Ca‐clays. When interlayer swelling predicted from a demixed‐ion model is plotted as a function of exchangeable‐sodium‐percentage (ESP) at constant salt concentration, a series of straight lines having increasing slopes and decreasing ESP‐axis intercepts with decreasing salt concentration is obtained. Similar plots involving a diffuse double‐layer (mixed‐ion) model produce a series of hyperbolas having concentration‐dependent intercepts on the swelling, rather than the ESP, axis. Most of the limited data available from the literature on soil and clay swelling in mixed‐salt solutions agree more closely with predictions from the demixed‐ion model, though neither model is fit exactly. Implications and limitations of each swelling model are discussed.
Arylsulfatase Activity of Soils
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

The detection of arylsulfatases (enzymes that hydrolyze aryl sulfates) in soils is reported, and a simple method of assaying soil arylsulfatase activity is described. This method involves colorimetric estimation of the p‐nitrophenol released by arylsulfatase activity when soil is incubated with buffered (pH 5.8) potassium p‐nitrophenyl sulfate solution and toluene at 37C for 1 hour, and it is rapid, sensitive, and precise. The procedure used to extract p‐nitrophenol stops arylsulfatase activity, develops the yellow color used to estimate p‐nitrophenol, and gives quantitative recovery of this compound. Studies of the properties of the arylsulfatases in soils are reported.
Exchangeable Aluminum As a Criterion for Liming Leached Mineral Soils
Authors: Kamprath E. J.
Published: July 2010

Lime rates equivalent to the amount of exchangeable Al reacted primarily with the exchangeable Al and reduced the Al saturation of the effective CEC to less than 30%. Lime rates greater than the equivalent amount of exchangeable Al resulted in appreciable amounts of nonexcharigeable acidity being neutralized. Below pH 5.4 the buffer capacity of the soils was primarily due to exchangeable Al. Lime applications based on the exchangeable Al extracted with a neutral unbuffered salt appear to be a realistic approach for Ultisols and Oxisols.
Infrared Analysis of Partially Deuterated Water Adsorbed on Clay
Authors: Leonard Ralph A.
Published: July 2010

Partially deuterated water (HDO) adsorbed on Na+, K+, Mg2+, and Ca2+ saturated montmorillonite clays was studied by use of infrared spectroscopy. Positions of the primary O‐D absorption band of adsorbed HDO were 2533, 2530, 2506, and 2526 cm‐1, respectively. In addition, a small secondary band was found at 2670 cm‐1. This band may arise from an O‐D group very weakly H‐bonded to a surface oxygen, or to water isolated in hexagonal cavities in the surface. No evidence of strong H‐bonding to the mineral surface was evident. Findings indicate that at low water contents, the exchangeable cation exerts the dominate force affecting the structure of the adsorbed water.
Separation of Clay Minerals and Soil Clays Using Isopycnic Zonal Centrifugation
Authors: Francis C. W. , Tamura Tsuneo , Bonner W. P. , Amburgey J. W.
Published: July 2010

The technique of isopycnic‐zonal centrifugation in a continuous nonaqueous density gradient was used in the purification and separation of standard clay minerals and soil clays. A suspending agent (polyvinylpyrrolidone) compatible with tetrabromoethane and ethanol stabilized clay suspensions produced multiple banding of systems which otherwise flocculated into one band. Data from x‐ray diffraction analyses revealed the technique is useful in purification of clay minerals and identification of clay minerals in soil clays; however the banding obtained from the clay fraction of a Dodge silt loam did not represent discrete bands of specific clay minerals.
Measurement of the Total Suction of Soils by a Thermistor Psychrometer
Authors: Kay B. D. , Low Philip F.
Published: July 2010

A detailed description of a thermistor psychrometer is presented. The psychrometer depends on differential cooling due to unequal evaporation rates of water droplets suspended from matched thermistors which are located above the sample and reference. The resulting difference in resistance between the thermistors is measured by a Wheatstone bridge and referred to a calibration curve for the determination of the total suction of the sample.

Results obtained by the psychrometer on a Brookston silt loam are shown to agree with those obtained by a pressure plate. However, results obtained by the psychrometer on a pure clay‐water system are shown to differ from those obtained by a tensiometer. A possible reason for this difference is given.
Zinc Adsorption by Calcareous Soils
Authors: Udo E. J. , Bohn H. L. , Tucker T. C.
Published: July 2010

Zinc adsorption was studied in suspensions of 10 calcareous Arizona soils in dilute ZnSO4 solutions. At low concentrations, Zn2+ adsorption was described by the Langmuir adsorption equation. The calculated Langmuir adsorption maxima were related to the carbonate and organic matter contents of the soils. When the added Zn2+ exceeded the adsorption maximum, the value of the (Zn)(OH)2 ion concentration product in solution corresponded to the solubility of zinc hydroxide or carbonate so long as soil carbonates were present. At lower amounts of adsorbed Zn2+ and/or when the soil carbonates had dissolved, the (Zn)(OH)2 product was about one hundred‐fold less indicating that the soils then retained Zn2+ about as strongly as zinc silicate, and more strongly than zinc hydroxide or carbonate.
Effect of Dyrene and Maneb on Nitrification and Ammonification, and Their Degradation in Tropical Soils
Authors: Dubey H. D. , Rodriguez Rita L.
Published: July 2010

The effect of 2,4‐dichloro‐6‐(o‐chloroanilino)‐s‐triazine (dyrene) and manganese ethylene bisdithiocarbamate (maneb) at 0, 15, 60, 240, and 960 ppm on nitrification of 100 ppm applied NH4‐N, and on ammonification of soil nitrogen, and the degradation of these fungicides, were studied in a lateritic clay and a fertile loam incubated at 24C for 16 weeks.

Inhibition of nitrification by the fungicides was lesser and of shorter duration in the rapidly nitrifying loam than in the slow nitrifying lateritic soil. The chemicals inhibited the ammonia oxidizing bacteria but not the nitrite oxidizing bacteria. Maneb was several times more toxic to the nitrifying organisms than dyrene, and its effect lasted even after the chemical was degraded. Ammonification was inhibited only at 960 ppm of the fungicides. There was no synergistic effect with regard to inhibition of nitrification or ammonification when the soil received both the fungicides. The fungicides were degraded faster in the rapidly nitrifying soil than in the slow nitrifying soil. Maneb was decomposed earlier than dyrene.