bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cation‐Exchange Capacity and Exchangeable Cations in Piedmont Soils of North Carolina
Authors: Coleman N. T. , Weed S. B. , McCracken R. J. 
Published: July 2010

AbstractSoils of the North Carolina Piedmont were analyzed for permanent‐ and pH‐dependent charge components of cation‐exchange capacity. Permanent charge was taken as the summation of exchangeable metal cations, including Al displaced upon leaching with a neutral salt solution; pH dependent charge was regarded as the amount of exchange acidity (BaCl2‐TEA) remaining after neutral salt leaching.Well‐developed upland soils had small permanent charges and large pH dependent charges. For soils of a given sequence, the permanent‐charge/pH‐dependent charge ratios (B2 and above) were smallest for the red end member. Deeper horizons often had very large permanent charges, as did the B horizons of some Planosols. Latosolic soils had smaller permanent‐charge/pH‐dependent charge ratios than did Red‐Yellow Podzolics.Permanent‐charge components of CEC were countered exclusively by metal cations. In acid soils Al predominated, while Ca and Mg neutralized most of the permanent charge in soils with pH's above 6. There were negligible amounts of electrostatically‐bonded H in any soil. Generally exchangeable Al increased with depth. Yellow Podzolic and Planosolic soils in particular tended to have large amounts of exchangeable Al in lower horizons.Percentage base saturation concepts are discussed, the conclusion being that a saturation percentage based on permanent charge is preferred.
Exchangeable Potassium Levels in Vermiculite and K‐Depleted Micas, and Implications Relative to Potassium Levels in Soils
Authors: DeMumbrum L. E. 
Published: July 2010

AbstractFe‐ and Mg‐rich micas were depleted of K in the laboratory by the action of sodium tetraphenylboron, and the products were examined by X‐ray diffraction. A natural vermiculite was included in this study. Exchangeable K was determined in relation to total K where possible.Nearly constant levels of exchangeable K were maintained by the vermiculite and weathered trioctahedral micas over the range of K concentrations at which fixation occurred. The materials functioned as K fixers below approximately 3% K2O but little fixation could be induced at moderate temperatures and K concentrations above 3% K2O. Total K below 3% K2O was not related to exchangeable K. Above 3% K2O, exchangeable K increased rapidly with K additions. Interstratified layer silicates were produced by K removal from the natural micas, and were also formed by additions of K to vermiculite. At natural levels of total K in the micas (7 to 10% K2O), 10Å. material was present; considerable 14Å. material was produced as removal of K approached completion.Dilution of the fixing mineral with montmorillonite resulted in exchangeable K levels which were very similar to those in the fixing mineral alone. Numerous workers have noted that certain soils seem to exhibit characteristic exchangeable K levels which are not altered appreciably by additions or removals of K. These data tend to substantiate such observations and seem to explain the characteristic K exchange levels within such soils.
Aluminum Studies: II. The Extraction of Aluminum from Some Florida Soils
Authors: Yuan T. L. , Fiskell J. G. A. 
Published: July 2010

AbstractA study of soil Al extraction by various chemical reagents has been conducted. Using N NH4OAc solutions buffered at six different pH levels, it was found that the lower the pH of the solution the more Al was extracted. Neutral normal solutions of BaCl2, CaCl2, KCl, NH4Cl, and a solution of BaCl2 in triethanolamine buffered at pH 8.1 extracted more Al than neutral N NH4OAc. Among neutral salts the bivalent cations seemed to be more efficient. BaCl2 in triethanolamine extracted much more Al than any of the neutral salts, probably due to the complexing capacity of triethanolamine.Three alkaline reagents—NaOH, NaF, and Na pyrophosphate—commonly used for organic matter extraction, were also tested. Each of these reagents extracted much more Al from sandy and sandy loam soils than the previous reagent group. This Al was believed to originate from various Al compounds in soils including aluminum hydroxide and phosphate and even aluminum silicates.In order to investigate the relationship between Al and phosphate release, a P‐fractionation procedure was used on a Red Bay fine sandy loam. In the extract of each fraction a high amount of Al was found, except with NH4Cl. Al hydroxide seemed to be the main source contributing to the high Al value obtained from alkalis and fluoride extractions.
Influence of Nitrogen Fertilization and Clipping on Grass Roots
Authors: Oswalt D. L. , Bertrand A. R. , Teel M. R. 
Published: July 2010

AbstractStrategic placement of P32 and root excavations revealed that roots of orchardgrass and bromegrass reached a greater depth when no N was applied. Nitrogen increased the root diameter and decreased the rate of elongation causing the plants to feed near the soil surface for a longer period of time. Defoliation stopped root growth within 24 hours and induced decomposition of the existing roots within 36 to 48 hours. Uptake of P32 placed in the existing root zone 24 to 48 hours after clipping was not detected until new roots reached the activated zone. New roots were initiated from basal leaf nodes of orchardgrass and rhizome nodes of bromegrass. Removal of all roots at the time of defoliation did not influence the rate of regrowth from transplanted sod plugs under optimum soil moisture conditions.
Tests of Capillary Flow Scaling
Authors: Elrick D. E. , Scandrett J. H. , Miller E. E. 
Published: July 2010

AbstractFour types of experiments testing predicted scaling relations are reported.In the first two, different liquids are compared in the same medium. The first compares hysteresis loops—liquid content vs. tension. The second compares conductivities at a certain tension.The third and fourth experiments concern entire flow systems; they compare systems constructed from different (but “similar”) media; only one liquid being used. The third experiment measures flow into the top of a dry column. The fourth measures drainage from a saturated column under a combination of tension and gravity.The results of all four experiments are in excellent agreement with theory when the media are clean sands. The hysteresis experiment was also run for media having increasing colloidal fractions. In the latter cases, the results show definite departures from theory which increase with the amount of colloid.
The Influence of Organic Matter Additions on Rock Phosphate Availability to Crops
Authors: Seatz Lloyd F. , Sterges Athan J. , Kramer James C. 
Published: July 2010

AbstractA greenhouse experiment was conducted to evaluate the effects of adding organic matter to the soil on the availability of rock phosphate from two sources. The treated soils were cropped successively to Sudangrass, ryegrass, and two crops of red clover. Treatments receiving additions of organic matter yielded higher in most cases than the corresponding treatment without added organic matter. Increased yields were attributed to the additional P in the organic matter rather than to the beneficial effect of the organic matter on the availability of rock phosphate. Treatments receiving Florida rock phosphate yielded more than corresponding treatments receiving Tennessee rock phosphate.
An Evaluation of Phosphorus Fertilizers Varying in Water Solubility: II. Broadcast Applications for Corn
Authors: Webb John R. , Pesek John T. 
Published: July 2010

AbstractSixteen field experiments were conducted, in which two or more phosphorus fertilizers differing in water solubility were compared in broadcast applications for corn. The tests involved rates of 20 to 80 pounds of available P2O5 per acre, and were located on soil types which tested low in available P and had a pH range from 5.5 to 7.1.Increasing the rates of applied P2O5 increased the P content of corn leaf samples taken at silking time, but the degree of water solubility of the P significantly influenced leaf P levels in only 1 of 11 experiments sampled. Grain yields were also increased by P2O5 rates but were not significantly affected by the sources of P at any of the test sites. Highly water‐insoluble sources tended to be slightly less effective in a few of the experiments.The general conclusion was that on the soils included in the study the degree of water solubility of the P was not an important factor in determining the effectiveness of fertilizers broadcast and plowed under for corn.
Influence of the Coarse Fraction in Two Maine Potato Soils on Infiltration, Runoff and Erosion
Authors: Grant Walter J. , Struchtemeyer Roland A. 
Published: July 2010

AbstractThe influence of the coarse material in Caribou and Thorndike soils on infiltration, runoff and erosion was studied with the use of a laboratory infiltrometer which applied water at 2.5 inches per hour but with energy of impact appreciably less than that in natural rain of the same intensity. Various sized coarse particles were removed from both soils to determine the function of the coarse fraction. There was a significant decrease in the rate of infiltration and likewise an increase in runoff as the particles > 12.7 mm. were removed from both soils. A further decrease in infiltration resulted when all material > 4.76 mm. was removed; however, the fraction between 4.76 mm. and 2.38 mm. did not have a significant effect on infiltration and runoff.The amount of soil in the runoff from the Caribou sample was found to be nearly proportional to the runoff. It also increased with runoff as the coarse fractions were removed from the Thorndike soil, but there was not a significant increase for the second and third trials on the same sample even though the runoff increased. Some of the practical implications of the coarse fraction are discussed in relation to land use and the possible removal of coarse material for increased mechanization of farming operations.
Effect of Iron, Aluminum and Humic Acid on Phosphorus Fixation by Organic Soils
Authors: Larsen J. E. , Warren G. F. , Langston Ruble 
Published: July 2010

AbstractStudies were conducted comparing the effects of Fe, Al, and humic acid on P fixation in two organic soils which had undergone different degrees of decomposition. It was shown that organic soils fix P similarly to other reported P‐fixing systems. Fe and/or Al additions increased phosphate fixation while humic acid resulted in an apparent negative absorption. Further, humic acid prevented absorption of P in the presence of limited quantities of Fe and Al.
Autotrophic Oxidation of Ammonium and Hydroxylamine
Authors: Engel M. S. , Alexander M. 
Published: July 2010

AbstractStudies of resting cell suspensions of Nitrosomonas europaea have demonstrated that high concentrations of hydroxylamine are stoichiometrically converted to NO2. The oxidation proceeded most rapidly above pH 7.5 and was affected by altering the relative concentrations of substrate and bacterial cells. Nitrification of NH4‐nitrogen was retarded by increasing alkalinity and high substrate levels, but the inhibition is not as marked as observed for the NO2‐oxidizing chemoautotrophs. The NH4 oxidation by intact cells was not stimulated by Fe, orthophosphate, HCO3, Mg, Cu or Zn but was inhibited by small quantities of cyanide and 2,4‐dinitrophenol.
The Effects of Several Factors on Volatilization of Ammonia Formed from Urea in the Soil
Authors: Ernst J. W. , Massey H. F. 
Published: July 2010

AbstractThe effects of several environmental factors on the volatilization of ammonia from surface applications of urea on Dickson silt loam soil were studied under laboratory conditions.Increasing temperature and/or soil pH markedly increased ammonia volatilization.Ammonia volatilization from pH 6.5 soil was essentially the same when urea was topdressed, mixed with the top ¼ inch of soil or topdressed and watered into the soil with ¼ inch of water. Thus, it may be assumed that urea diffused through the soil to approximately the same extent with each of the three treatments.Some ammonia volatilization occurred without a concurrent drying process in the soil, but greater volatilization occurred when moisture was lost from the soil. The drying rate, however, varied over a wide range without affecting the rate of ammonia volatilization. Under conditions of very rapid drying, the soil became dry after 4 to 5 days of aeration, and ammonia volatilization was markedly decreased, presumably because hydrolysis of the urea was retarded due to lack of moisture.Ammonia volatilization was found to be directly related to initial soil moisture content presumably through the effect of this variable on the duration of the drying process.
Some Useful Techniques and Accessories for Adaptation of the Gas Chromatograph to Soil Nitrogen Studies
Authors: Smith Donald H. , Clark Francis E. 
Published: July 2010

AbstractSample‐handling procedures and certain modifications or accessories for the gas chromatograph that have been found useful in examining soil atmospheres for gaseous forms of nitrogen are described. Also described are columns and techniques that permit the separation and measurement of molecular N, N2O, NO, NO2, NH3, O2 and CO2. A special gas sampling valve, a manifold assembly, a multiple selector valve and a needle and manometer arrangement are diagrammed.
Cobalt Reactions with Montmorillonite
Authors: Hodgson J. F. 
Published: July 2010

AbstractSpecific reactions between montmorillonite and Co in low concentrations were studied in the presence of excess CaCl2. Two forms of bound Co were distinguished. One form, characterized as being slowly dissociable, appears to be bound in a monolayer by chemisorption and will exchange with Cu++, Zn++, or other Co++ and to a lesser extent with ions of other transition metals but not with Ca++, Mg++, or NH4+. A second form of Co did not dissociate and could not be extracted from the mineral with 2.5% acetic acid. This fraction, which was not characterized, is thought to either enter the crystal lattice or be occluded in the precipitation of another phase.
Phosphate Phase Equilibria in Soils
Authors: Lindsay W. L. , Moreno E. C. 
Published: July 2010

AbstractThe activity isotherms for AlPO4 · 2H2O (variscite), FePO4 · 2H2O (strengite), Ca10(PO4)6F2 (fluorapatite), Ca10(PO4)6(OH)2 (hydroxyapatite), Ca4H(PO4)3 · 3H2O (octocalcium phosphate), and CaHPO4 · 2H2O (dicalcium phosphate dihydrate) were represented on a single solubility diagram in which a function of the phosphate activity in solution was plotted against pH. This plot is useful for assessing the relative stabilities of these phosphate compounds and for predicting their transformations in soils upon the application of fertilizer or lime.For this development, the assumptions were made that Al3+ activity in soils was limited by the solubility of gibbsite, the Fe3+ activity by the solubility of goethite, F‐ activity by that of fluorite, and the Ca++ activity was arbitrarily selected as that of a 0.005M solution of a monovalent salt. Equations and graphs are included for modifying the basic diagram so as to correspond to any Al3+, Fe3+, F‐, or Ca++ activity that may be found in soils or that may be established during a particular soil extraction.
Correlation of Nitrogen Soil Tests With Nitrogen Uptake by the Tobacco Plant
Authors: Peterson L. A. , Attoe O. J. , Ogden W. B. 
Published: July 2010

AbstractGreenhouse and laboratory studies were conducted on soils collected from 37 Wisconsin tobacco fields to evaluate their capacity to supply nitrogen for two successive tobacco crops. Correlation analyses were made between the nitrogen content of each crop and the nitrogen determined by the various soil tests on the samples taken before the first crop. Highly significant correlation coefficients of 0.97 and 0.90 were obtained for soil nitrate nitrogen and Aspergillus niger tests, respectively. However, these tests were not significantly correlated with nitrogen uptake by the second crop, no doubt a result of depletion of the nitrates by the first crop. Similar results were obtained by dividing the soils into Prairie and Gray‐Brown Podzolic groups, except that a highly significant coefficient was obtained between the Aspergillus niger test and nitrogen uptake by the second crop for the Prairie soils. The tests which determined all or a portion of the organic nitrogen correlated at significant or highly significant levels with the nitrogen content of the second crop but not by the first crop. This lack of consistency between crops was undoubtedly due to the pronounced effect of the higher content of nitrate nitrogen in the soil prior to the first crop. Highly significant correlation coefficients were obtained between total soil nitrogen and each of the following: alkaline permanganate nitrogen (0.95), percentage organic matter (0.99), nitrification rate (0.65) and the amount of ammonia nitrogen extracted by various concentrations of sulfuric and hydrochloric acids (0.59 to 0.71).
The Significance of the Suspension Effect in the Uptake of Cations by Plants from Soil‐Water Systems
Authors: Olsen R. A. , Peech Michael 
Published: July 2010

AbstractThe significance of the suspension effect (greater cation concentration or activity in the soil suspension than in the equilibrium dialyzate) in determining the uptake of cations by plant roots was evaluated by comparing the rate of uptake of Rb+ and Ca++ by excised roots of barley and mung beans from a suspension of clay or cation‐exchange resin with that from the corresponding equilibrium dialyzate. Although the cation concentration of the clay or resin suspension greatly exceeded that of the corresponding equilibrium dialyzate, the rate of uptake of Rb+ or Ca++ by the roots was found to be exactly the same from both the suspension and its equilibrium dialyzate.The results of this study are at variance with the prediction of the contact‐exchange theory but are in agreement with the deductions based on theoretical considerations of the consequences of the root surface or volume charge distribution. The significant conclusion that may be drawn, however, is that the composition of the soil solution or the equilibrium dialyzate should completely characterize the ionic environment of plant roots in soil‐water systems.
Determination of Reserve Sulfur and Soluble Sulfates in Soils
Authors: Bardsley C. E. , Lancaster J. D. 
Published: July 2010

AbstractOrganic and reduced inorganic sulfur (reserve sulfur) are converted to sulfates by ignition of a soil‐sodium bicarbonate mixture at 500° C. Converted and soluble sulfates (soil sulfur) are then extracted with a solution that is 2N to HAc and 0.1N to NaH2PO4·H2O and determined turbidimetrically as BaSO4 after acidifying a portion of the filtrate with 1:1 HCl. Acceptable recovery of sulfur has been obtained from elemental sulfur, plant material, methionine, cystine, and cysteine.Soluble sulfates are extracted from a separate sample with 0.5N NH4OAc + 0.25N HAc. Activated charcoal is added to decolorize the extract. A portion of the filtrate is acidified with 1:1 HCl containing a “seed” solution of sulfate, and sulfur is determined turbidimetrically as BaSO4. Reserve sulfur is the difference between soil sulfur and soluble sulfates.The multiple correlation of reserve and sulfate‐sulfur with total nitrogen in soils was highly significant (R = 0.971). Reserve sulfur was highly correlated with yield of sulfur from three harvests of white clover grown in the greenhouse (R = 0.790). The relation of reserve sulfur and sulfates to the sulfur status of soils is discussed.
Use of the Rainulator for Runoff Plot Research
Authors: Meyer L. Donald. 
Published: July 2010

AbstractThe portable rainfall simulator, known as the rainulator, which has been recently developed at Lafayette, Indiana, was designed for use as a research tool to aid in more rapidly evaluating factors that influence erosion, runoff, and infiltration. Intensities of 2½ or 5 inches per hour with near the kinetic energy of natural rainfall at these intensities are produced. Other characteristics which are desirable for runoff and erosion research on rectangular field plots are embodied in the design. The number and length of plots to which simulated rainfall may be applied simultaneously may be varied by varying the number of units used.The rainulator will be used primarily for obtaining comparative evaluations of various topographic, soil, water, crop, and management factors under field plot conditions. Numerous factors are well suited to study by this method. The types of comparisons and evaluations which are and are not well adapted to study on rectangular field plots in general and specifically with the rainulator are also discussed.
Some Aspects of Phosphate Adsorption by Charcoal
Authors: Beaton J. D. , Peterson H. B. , Bauer Norman 
Published: July 2010

AbstractAs a basis for eventually evaluating the effect of charcoal, formed during forest fires, on the availability of phosphate ions in the soil, the thermodynamics of aqueous phosphate adsorption on six typical synthetic and natural charcoal materials is investigated. A standard adsorption process is defined under the justifiable assumptions that primary orthophosphate is specifically adsorbed, probably through hydrogen bonding; and that the counter‐ion, K+, is nonspecifically adsorbed or oriented in the diffuse double layer. Adsorption isotherm data at 25°, 35° and 45° C. and surface area measurements allow determinations of the changes in free energy, ΔF0θ, enthalpy, ΔH0θ and entropy, ΔS0θ for the standard adsorption process. This process is endothermic for the four most active charcoals. The shapes of the isotherms indicate that at least two types of adsorption sites or processes are involved, at high phosphate concentrations, in all cases. The four most active charcoals show an increase in adsorptive capacity with increasing temperature, associated with large positive values of ΔS0θ. X‐ray diffraction patterns show that the four most active charcoals have graphite‐like structures, whereas the other two seem to have, largely, a three‐dimensionally cross‐linked structure. The adsorption of phosphate per unit area increases in the order soil surface, lodgepole pine, duff, B & A Code 1551, Darco S51 and Darco G60 charcoals.Theoretical interpretation of the thermodynamic data indicates that, at least for the four most active charcoals, an extensive dehydration of the phosphate and/or charcoal surface is a distinctive part of the adsorption mechanism.