bluuebunny/crossref_metadata_2025_split huggingface dataset:
Iron Adsorption by Montmorillonite Systems: II. Determination of Adsorbed Iron
Authors: Page A. L. , Whittig L. D. 
Published: July 2010

AbstractComparison of methods for determination of Fe adsorption capacity of montmorillonite and a qualitative method for differentiation of adsorbed and precipitated Fe are presented.Separate H‐montmorillonite samples (Wyoming Clay Spur, < 1µ diameter) were exchange‐saturated by washing with FeCl3, Fe2(SO4)3 and Fe(NO3)3 solutions. Excess ions were removed with either distilled H2O, absolute methanol, 95% ethanol, or 0.003M HCl. Fe retained by the systems after washing was removed with acidified 1N NH4OAc.Fe(III) removed after 0.003M HCl washing was essentially the same in all systems (between 1.17 and 1.25 me. per g.) but was much higher (up to 2.2 me. per g.) and quite variable from H2O or alcohol‐washed samples. The 0.003M HCl washing was found to remove negligible amounts of adsorbed iron. Base titration curves of all the samples were essentially the same, indicating that each system retained the same amounts of adsorbed Fe.The data indicate that excess Fe was precipitated in the systems where H2O and alcohols were employed for removal of the excess ions. Data are presented which show that adsorbed Fe may be qualitatively differentiated from precipitated Fe in the systems studied by using NH4F solution as an extracting reagent.
Calibration and Characteristics of Two Neutron Moisture Probes
Authors: van Bavel C. H. M. , Nielsen D. R. , Davidson J. M. 
Published: July 2010

AbstractThe effect of the size of cylindrical containers filled with soil on the calibration of two types of neutron probes was investigated for moisture contents up to 0.25 volume fraction. Neutron count rates were appreciably affected by the value of both diameter and height up to 3 feet. Differences between 3 and 4 feet were samll.The response of the end‐source probe was linear within the range investigated (0 to 0.40 volume fraction). The data also show that the end‐source probe design as compared with the centered‐source design is more efficient and, therefore, requires a smaller radioactive source for equal precision.Once an accurate calibration with soil is available, verifying calibration of probes may be done with NaCl or H3BO3 solutions, limited to probes of identical design but differing efficiencies or source strengths. Relations found between soil moisture content and solution concentration are given.A discussion of the range of measurement of soil moisture content with neutron probes is presented, comparing various literature data.
Soil Moisture Measurements with the Neutron Method Supplement Weighing Lysimeters
Authors: McGuinness J. L. , Dreibelbis F. R. , Harrold L. L. 
Published: July 2010

AbstractEvaluation of soil moisture changes with the neutron method agreed closely with that obtained from the weighing lysimeters. Evapotranspiration can be determined with either method by the equation ET = P ‐ G ‐ Q ± Δ M where ET = evapotranspiration, P = precipitation, G = percolation, Q = surface runoff and ΔM = change in soil moisture.Differences were shown in the soil moisture extraction pattern under deep‐rooted and shallow‐rooted meadow crops. The hydrologic implications of this difference are discussed.
The Effect of Temperature and Moisture on Exchangeable Potassium
Authors: Burns Allan F. , Barber Stanley A. 
Published: July 2010

AbstractThe 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.
Psychrometric Measurements of Soil Samples Equilibrated on Pressure Membranes
Authors: Richards L. A. , Ogata Gen 
Published: July 2010

AbstractThe osmotic pressure or solute suction (SS) of the extract from a “saturated” soil paste can be measured with a thermoelectric psychrometer which is calibrated by use of standard osmotic solutions. The same psychrometric procedure can be used to measure the total soil‐moisture stress or total suction (TS) of water in soil that has been equilibrated with a pressure membrane at known soil‐moisture tension or matric suction (MS). From membranous and psychrometric measurements, the difference ΔS = TS ‐ (MS + SS) was evaluated for 134 samples of Pachappa soil at three SS levels (0.3, 2.5, and 5 bar) attained by leaching with calcium chloride solutions and three MS levels (5, 10, and 15 bar). Mean ΔS values at 5, 10, and 15 bar MS were, respectively, −0.6, −0.4, and −0.1 bar. Mean ΔS values at 0.3, 2.5, and 5 bar SS were, respectively, −1.0, +0.04, and +0.5 bar. Standard deviation values for MS, SS, and TS, respectively, were 0.07, 0.1, and 0.5 bar.
Relationships Between Particle Size and Potassium Release From Biotite and Its Analogues
Authors: Mortland M. M. , Lawton K. 
Published: July 2010

AbstractThe relationships of particle size of biotite to K release, oxidation state of iron, cation‐exchange capacity, and total charge of the mineral were studied. The first stage of alteration, accomplished by leaching 15 minutes with 0.1N NaCl, showed a marked relationship to particle size. At this point, the only K removed was that on the external surfaces of the particles, and consequently the fine particles lost a larger percentage of their total K at this stage than did the larger particles. However, by the last stage where 50% of the total K had been removed, the large particles generally had lost as much as the fine. Once the initially exchangeable K has been removed, the release of matrix K from the particles is suggested to be controlled by the concentration gradient and the geometry of the diffusion path available for the exchanging ions, Na and K. The equilibrium concentration of K in 0.1N NaCl was shown to be proportional to the total K content of biotite which had been altered to different levels of total K. The oxidation state of iron in the biotite was shown to be a function of particle size and extent of alteration.
The Effect of Surface Soil Thickness on Corn Yields: I. As Determined by a Series of Field Experiments in Farmer‐Operated Fields
Authors: Engelstad O. P. , Shrader W. D. , Dumenil L. C. 
Published: July 2010

AbstractA study was conducted to determine the effect of surface soil thickness on yields of corn and to learn whether nitrogen fertilizer would substitute for surface soil thickness in producing yields of corn on the minimal Brunizem soils of southwestern Iowa.During 1957 and 1958, 55 nitrogen fertilizer experiments were distributed over the existing range of surface soil thickness. The corn yield obtained from each of 5 nitrogen fertilizer rates was measured at each site. By means of a multiple regression analysis it was found that application of nitrogen fertilizer at the rate of 100 pounds per acre for corn completely substituted for surface soil in 1957 but failed to do so in 1958. Under the soil and climatic conditions that prevail in the area studied, nitrogen fertilizer can substitute completely for surface soil thickness in some years but not in others. Apparently, climatic factors influence the degree of such substitution.
Water Infiltration into Stratified Soil
Authors: Miller D. E. , Gardner W. H. 
Published: July 2010

AbstractA laboratory investigation was made of the effects of textural and structural stratification within the profile on rate of water infiltration into soil. A recording infiltrometer was devised and a method developed for obtaining uniformly packed tubes of soil. Infiltration data were obtained for soil conditioner treated Palouse silt loam. These data were used to test several infiltration equations found in the literature. It was observed that none of the equations tested adequately describe the experimental data.Effects of strata within soil were related to the pore characteristic differences between the layering material and the surrounding soil. When most of the pores in a layer were larger than those in the surrounding soil, infiltration was temporarily inhibited after the wetting front reached the layer. The degree of inhibition was increased when the pore sizes in the layer were increased. Water must accumulate at a layer‐soil interface until it is at a tension low enough to allow it to move into pores in the layer. Water movement into the surface is reduced while the accumulation takes place.
Retention and Cation‐Exchange Properties of Organic Matter in Coastal Plain Soils
Authors: Kamprath E. J. , Welch C. D. 
Published: July 2010

AbstractSoil organic matter is quite important as a source of cation‐exchange capacity in Coastal Plain soils. The amount of organic matter in well‐drained soils is directly related to the clay content. In the very poorly drained soils this direct relationship was not apparent.The cation‐exchange capacity of soil organic matter varied from 62 to 279 me. per 100 g. The nature of the exchangeable hydrogen of organic matter was measured by the use of several replacing solutions. A portion of the exchangeable hydrogen in soil organic matter was found to come from strong acid groups.
Evaluation of Air‐to‐Water Permeability Ratio for Measuring Differences in Soil Structural Stability Under Ten Cropping Systems
Authors: Cohen O. P. , Strickling E. 
Published: July 2010

AbstractAggregate and structural stabilities were determined on samples taken under 10 cropping systems on Beltsville silt loam soil. Water stability of aggregates from 2 mm. to 4.76 mm. in diameter was measured by the wet‐sieving method of Bryant, Bendixen, and Slater. Structural stability was determined on samples < 2 mm. and < 1 mm. by the air‐to‐water permeability ratio method of Reeve. The measurement of soil aggregate stability by wet‐sieving distinguished six different groups of cropping systems according to Duncan's Range Test (4). The order of placement of the cropping systems was in agreement with other experimental results of Wilson et al. concerning the effect of cultivation and forage crops on aggregate stability. The measurement of structural stability by the air‐to‐water permeability ratio method did not distinguish soil structural differences associated with the cropping systems. Attempts to increase the sensitivity of the air‐to‐water permeability ratio failed. Water permeability offers some promise as a measurement of structural stability differences associated with cropping systems.
Problems in Clay Mineral Identification by X‐Ray Diffraction
Authors: Harward M. E. , Theisen A. A. 
Published: July 2010

AbstractX‐ray diffraction studies of Oregon soil clays during the past few years have resulted in the observance of a number of phenomena that were somewhat disconcerting. Results of a number of different studies have indicated that the clay minerals identified in a given sample are dependent upon specimen carriers, method of Fe removal, dispersion reagents, cation saturation of clay, and in some cases, peeling of specimens. Further, the situation is complicated by the fact that the effects vary not only with different soils, but also to some extent with different size fractions of the same soil.Data obtained lead to consideration of the possible extent that clay mineral identification by X‐ray diffraction may be arbitrary and empirical. A question is raised as to differentiation of clay minerals which may occur naturally in a given soil from those which may appear as a result of sample preparation. Certainly, the results reported here strongly suggest the need of a combined and intensive effort to establish clay mineral identification on a better and more universal foundation than appears to be the case at the present time.
The Solubility of Gibbsite in Aqueous Solutions and Soil Extracts
Authors: Frink C. R. , Peech Michael 
Published: July 2010

AbstractThe solubility of gibbsite was determined in supersaturated and undersaturated AlCl3 solutions as well as in 0.01M CaCl2 soil extracts. The rate of dissolution of gibbsite in undersaturated solutions was extremely slow. In supersaturated solutions that were seeded with gibbsite, equilibrium was established after 1 to 3 months. The solubility product, expressed as pKsp, was found to be 33.5 at 25°C., which agrees well with a value of 33.8 calculated from thermodynamic data. Owing to the relatively large amount of adsorbed aluminum ions as compared to that present in solution, the time necessary to reach the solubility product of gibbsite was found to be much longer in a clay or soil suspension than in an aqueous solution having the same pH value.
Molecular and Equivalent Weights of the Organic Matter of a Podzol
Authors: Schnitzer M. , Desjardins J. G. 
Published: July 2010

AbstractThe number‐average molecular weights of the organic matter of the A0 and Bh horiozons of a Podzol, determined by freezing point depression in sulfolane, were 1684 and 669, respectively. From the molecular weights, in conjunction with ultimate and functional group analyses, molecular formulae were calculated. These were C75H33O17N3 (COOH)3(OH)12(CO)2 for the A0 and C21H12(COOH)6(OH)5(CO)2 for the Bh organic matter. The presence of relatively large numbers of functional groups in the Bh molecule offers interesting possibilities for metallo‐organic interactions.The equivalent weights of the same organic matter preparations, measured by discontinuous potentiometric titrations, were 165 for the A0 and 76 for the Bh organic matter. The ratio of molecular to equivalent weight was 10 for the A0 and 9 for the Bh material. These ratios were in both cases equal to the sum of carboxyl plus phenolic hydroxyl groups in the two molecules.
Response of Slash Pine to Nitrogen and Phosphorus Fertilization
Authors: Walker L. C. , Youngberg C. T. 
Published: July 2010

AbstractA slash pine plantation in the lower Coastal Plain of Georgia was fertilized at age 9 with 200 pounds per acre of N, 44 pounds per acre of P, and with both elements. Diameter and basal area growth response to N was obtained for each of the first 3 years following treatment, but maximum stimulation occurred the year after fertilization. Diameter growth of the largest 400 trees per acre was also significantly increased by N treatment. P supplements gave no response in the deep sandy soil. Height growth responses were not apparent.Concentration of N in needles was increased 1 year after treatment, but by the end of the third growing season, no differences were apparent for N, P, K, and Ca content in foliage. Chemical analyses are also given for L and F layers, the latter being high in N. Neither needle lengths nor soil analyses differed between treatments after 3 years.
Simplified Accounting for Membrane Impedance in Capillary Conductivity Determinations
Authors: Kunze Raymond J. , Kirkham Don 
Published: July 2010

AbstractMiller and Elrick's method of computing capillary conductivity for nonnegligible membrane impedance has been modified to reduce the amount of calculation required for converting pressure plate outflow data to capillary conductivities. Plate impedance need not be measured and variable contact impedance is accounted for. The method is most practical if accurate time and outflow measurements can be made shortly after making a small step change in pressure. An apparatus is described to make such measurements. To minimize diffusivity changes associated with moisture outflow, only the initial portion of the outflow data resulting from the step change in pressure is used. The relationship between capillary conductivity and moisture content is shown for two soils.
Evidence of Polymolecular Film Formation During the Adsorption of Water and Ethylene Dibromide on Glass Spheres
Authors: Jurinak J. J. , Waldron L. J. , Vomocil J. A. 
Published: July 2010

AbstractThe importance of adsorptive forces in monodispersed glass bead systems, at high relative pressures, was studied during the adsorption of water and ethylene dibromide by microscopic Pyrex and alkali glass beads, i.e., ideal soil. The analysis of the adsorption data by the Frenkel‐Halsey‐Hill isotherm equation, applicable at high surface coverages, allowed differentiation between capillary condensation and multilayer adsorption. Polymolecular adsorption accounted for all adsorption of water up to P/P0 = 0.98 with no indication of condensation. The type of glass had a marked effect on the nature of water interaction. Evidence is presented which indicates that both ethylene dibromide and ethyl alcohol (data from literature) exhibit phase transitions in the multilayer region of adsorption.
Some Chemical Characteristics of Submerged and Reclaimed Sediments of the San Francisco Bay System
Authors: Grass Luther B. , Aronovici V. S. , Muckel Dean C. 
Published: July 2010

AbstractSamples of water, and of sediments deposited under the influence of sea water, were taken from the San Francisco Bay system. Samples of both reclaimed and unreclaimed sediments were taken from areas immediately adjacent to the bay for comparative purposes. Total sulfur and organic matter were determined and the saturation extracts analyzed for Ca, Mg, Na, and K.These analyses show that the submerged sediments were in equilibrium with the water from which they were collected. The relative concentrations of cations in the water were: Ca, 3.8%; Mg, 20%; Na, 75%; and K, 1.2%. The total cation concentration was 470 me. per liter. Increased accumulation of sulfur during the emergence of the sediments from the water and the oxidation of reduced sulfur to H2SO4 accounts for the reduction in pH in reclaimed sediments. A curve was developed for use in predicting ultimate pH from sulfur analyses of the sediments.
Total Sulfur and Sulfate Sulfur Content in Subterranean Clover as Related to Sulfur Responses
Authors: Jones Milton B. 
Published: July 2010

AbstractSubclover was grown on sulfur deficient soil in the greenhouse and in the field with various rates of S applied. Plants were harvested in the greenhouse when the first, third, and fifth flower per stem appeared, and the plant material was separated into leaflets, petioles and stems. The total S and SO4‐S concentrations in the plant did not change significantly over the three stages of growth.The first 20 pounds per acre increased yield and the organic‐S concentration, but did not change the SO4‐S concentration in the plant. Rates of S > 20 pounds per acre did not increase the yield, but increased the SO‐4S more than the organic S fraction in the plant. More SO4‐S accumulated in the stems than in the petioles or leaflets at high rates of applied S, but at low levels of S there was little difference between the SO4‐S concentration of the three plant parts. There was more organic‐S in the leaflets than the other plant parts at all levels of applied S.The SO4‐S concentration was determined in whole subclover tops grown in the greenhouse on 13 soils fertilized with sulfur and phosphorus. Eight of the soils produced clover with SO4‐S concentrations of 170 ppm. or less when unfertilized and each of these soils produced more clover when sulfur was applied if adequate phosphorus was available. The SO4‐S concentration in whole subclover plants showed the same relation to yield in the field as in the greenhouse. The SO4‐S concentration in subclover identified plants deficient in S, but did not indicate the degree of S deficiency.
A Study of the Morphology and Pedogenesis of a Medial Chernozem Developed in Loess
Authors: Bourne W. C. , Whiteside E. P. 
Published: July 2010

AbstractBozeman silty clay loam is a well‐drained, medial northern Chernozem. The A horizons are very dark grayish brown and granular; the B are dark grayish brown to dark brown and compound prismatic‐blocky; the C are calcareous, pale brown, massive silt loams. Particle‐size distributions of the associated loess deposits indicate that local floodplains contributed significantly to their silt and sand fractions, and that some stratification must have occurred during their deposition. During pedogenesis, marked changes have occurred in the microfabric of the soil and acid‐soluble material, mostly lime, has been moved into and through the Cca horizon. The principal clays are montmorillonite and illite. During pedogenesis, there has been an increase in total clay in the solum, a movement of some clay downward, and a reconstitution of much of the clay of the A horizons to randomly interstratified forms. Calculations show the relative rate of clay formation to be highest in the lower A.
Soil Layering and Compaction Effects on Unsaturated Moisture Movement
Authors: Eagleman J. R. , Jamison V. C. 
Published: July 2010

AbstractMeasurements of the velocity of flow and hydraulic gradients were obtained in the suction range of 0 to 700 cm. of water across the plane of contact for three different soil textural pairs, two of which were sampled from naturally occurring textural breaks in alluvial soil profiles. The hydraulic conductivity values across the textural breaks indicated that the soil properties were favorable for moisture transfer from large pores to smaller pores, but that a barrier existed for water movement from smaller pores to large pores. The barrier developed as the suction increased in a coarse layer in contact with finer material. With water removal from the larger pores at moderately low suctions, flow from the fine soil layer into the coarse material was reduced. In the naturally occurring breaks in soil texture it was found that the compaction of the different soil layers determined the degree of expression of the barrier to water movement.
A Greenhouse Study of Relations between Nutrient Movement and Conversion in a Sandy Soil and the Nutrition of Slash Pine Seedlings
Authors: Bengtson George W. , Voigt Garth K. 
Published: July 2010

AbstractA greenhouse lysimeter study was made of plant‐soil‐water relations determining the availability of N, P, and K from different fertilizer sources to slash pine seedlings growing in Lakeland fine sand.Leachate analyses showed that virtually all NH4NO3 and KCl applied to the surface of the soil in bare lysimeters was leached from the upper 12 inches of the profile within 4 weeks when water was applied at the rate of 4 inches per week. At the same watering rate, urea‐formaldehyde and potassium calcium pyrophosphate showed substantially lower leaching losses. No significant leaching of P was observed.The presence of pine seedlings in the lysimeters prevented or reduced leaching of N and K at low and intermediate watering levels but at the high level the seedlings were relatively ineffective in reducing nutrient losses.Chemical analyses of the seedlings showed greater nutrient uptake over a 17‐week period from the readily soluble N and K sources at 1 and 2 inches of water per week. At the higher watering rate (4 inches per week) more N and K was taken up from the slowly soluble sources. These differences were reflected in seedling growth.Fertilized seedlings transpired from 30 to 80% more water than the controls, yet their water use per gram of dry matter produced was 25 to 50% less than that of control seedlings.