bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Mineral Forms in Andepts from Chile
Authors: Espinoza W. , Rust R. H. , Adams R. S. 
Published: July 2010

AbstractThe mineralogy of two undisturbed volcanic soils from Chile (Typic Dystrandepts) and of the sand and clay‐size particles of the soil residues was studied by using ultrasonic, scanning electron microscope, X‐ray diffraction, transmission electron microscope, infrared spectroscopy, differential thermal analysis, and electron microprobe techniques. The effects of removal of organic matter, free iron and aluminum oxides, and amorphous alumino‐silicates was evaluated in the X‐ray, DTA, and IR analyses. The soils are characterized by an amorphous inorganic matrix in a flocculated state with a sponge type structure. This matrix presents a high specific surface (225 m2/g), CEC of about 45 meq/100g at pH 7.0, low base saturation (< 20%) and bulk density of 0.9 to 1.1 (g/cm3) and SiO2/Al2O3 molar ratio of 2.0 to 4.0. Organic matter appeared in some well preserved structures, partially due to silica accumulation. The principal primary minerals are fresh volcanic glass and K‐feldspars and the principal secondary mineral is allophane or an amorphous analog. The removal of organic matter, free iron and aluminum oxides and amorphous alumino‐silicates did not alter the DTA, X‐ray and IR patterns.
Clay Mineralogy of Selected Soils in Southern Nigeria
Authors: Gallez A. , Juo A. S. R. , Herbillon A. J. , Moormann F. R. 
Published: July 2010

AbstractClay minerals in eight soil profiles from southern Nigeria were investigated by means of X‐ray diffraction, infrared spectroscopy, differential thermal analysis, and electron microscopy. These soils are derived from basement complex rocks, arenaceous sedimentary rocks and basalts.Kaolinite is the most predominant clay mineral for all the soils studied. A pronounced variation in clay mineralogy was found in the soils derived from basement complex rocks sampled at various locations along a toposequence. Halloysite occurs in freshly weathered materials, while smectite is found in poorly drained, lower members of the toposequence.Gibbsite occurs in soil derived from cretaceous arenaceous rocks in the high rainfall area. Among all soils studied, the highest amounts of amorphous Al silicate and extractable Fe and Al oxides were found in those derived from basalts. In all cases, Fe oxides exist predominantly in crystalline forms.
Decomposition of Specifically Carbon‐14 Labeled Benzoic and Cinnamic Acid Derivatives in Soil
Authors: Haider K. , Martin J. P. 
Published: July 2010

AbstractSpecifically 14C‐labeled benzoic, phenolcarboxylic, and hydroxycinnamic acids were synthesized. The loss of the labeled carbon as 14CO2 upon incubation at 100 and 1,000 ppm in a neutral soil with and without the addition of 2% freeze‐dried humic acid or 0.5% finely ground peach wood (Prunus persica) was followed over a 12‐week incubation period. Under the experimental conditions the phenolic compounds were readily degraded in the soil. Within 1 week about 90% of the COOH carbon of p‐hydroxybenzoic, syringic, vanillic, and anisic acids had evolved as CO2. After 12 weeks this had increased to about 95%. Loss of the 14COOH carbon of 6‐methylsalicylic acid was about 75% at 1 week and 87% after 12 weeks. About 42 to 85% of the side chain carbons of p‐hydroxycinnamic acid and caffeic acids evolved as CO2 and from 66 to 85% of the ring carbon of protocatechuic, benzoic, vanillic, veratric, and caffeic acids was lost over the incubation period. The addition of peach wood or humic acid exerted very little effect on the decomposition rate and total decomposition of the phenols and the phenols did not influence the decomposition rate or total decomposition of the peach wood. The percentage distribution of the residual activity from 3‐14C p‐hydroxycinnamic acid, ring‐14C benzoic acid, and O14CH3 syringic acid varied from 14 to 21, 17 to 32, and 23 to 59% for the humic acid, fulvic acid, and residual soil fractions, respectively. Linkage into model phenolase polymers greatly retarded decomposition rate. Loss of ring carbon varied from 3 to 6% and side chain and COOH carbons from 8 to 75%. The higher losses occurred from COOH groups of single hydroxybenzoic acids linked into model phenolase polymers from hydroxytoluenes and hydroxyphenols.
Fragipans in Pennsylvania Soils: Properties of Bleached Prism Face Materials
Authors: Ranney R. W. , Ciolkosz E. J. , Cunningham R. L. , Petersen G. W. , Matelski R. P. 
Published: July 2010

AbstractBleached prism faces are a common feature of soil fragipan horizons. Particle size and chemical and clay mineralogy data indicate these zones are areas of accumulation of material from horizons above. The data also indicates that two processes are active in the movement of material into the prism face area. These processes result in bimodal distribution of particle sizes in the prism face areas. The exact nature of the processes is unclear and may involve both deposition and some stripping.
Hammer Seismic Timing as a Tool for Artificial Recharge Site Selection
Authors: Bianchi W. C. , Nightingale H. I. 
Published: July 2010

AbstractHand‐carried hammer impact seismic timing equipment utilizes the physics of seismic wave refraction to explore stratigraphic changes deeper then those found on soils maps. In alluvial areas, artificial recharge and liquid waste disposal sites are selected from sandy, single‐grained soil series noted for their high water‐transmitting properties through the surface 2 m. The surface horizon seismic velocity exhibited by these soils in the San Joaquin Valley has a very narrow range (V1 = 315–440 m/sec) which gives good definition to the refraction off the second horizon (V2 = 610–2,100 m/sec). Accurate information on depth and horizontal continuity of this second horizon can be obtained in areal surveys. A third horizon may often be described, but its areal continuity is usually masked by intermediate discontinuous layers above it of equal or lesser refractivity. All these horizons are of hydraulic significance for ground‐water recharge by water spreading.
Reflectance Differences Between Crop Residues and Bare Soils
Authors: Gausman H. W. , Gerbermann A. H. , Wiegand C. L. , Leamer R. W. , Rodriguez R. R. , Noriega J. R. 
Published: July 2010

AbstractTo find the best spectral waveband for identifying crop residues by remote sensing, reflectance spectra of standing and littered crop residues were compared, and the utility of ERTS‐1 Multispectral Scanner (MSS) data for distinguishing soils with crop residues from bare soils was tested.Field spectroradiometric investigations were conducted using the 0.5‐ to 1.8‐µm waveband. Crop residue littered on the soil had higher reflectance than bare soil, but standing crop residue had lower reflectance than bare soil.The ERTS‐1 MSS digital counts (signal strengths) were statistically different between soils with and without crop residues more times (8 out of 12) for band 4 (0.5 to 0.6 µm) than for bands 5 (0.6 to 0.7 µm), 6 (0.7 to 0.8 µm), and 7 (0.8 to 1.1 µ), or for band ratios 4/7, 5/7, 4/6, and 5/6. Statistically, for band 4, soils with crop residues had lower reflectance than bare soils five out of eight times.Present reflectance techniques are unable to distinguish quantities of crop residue on the soil, and better parameters are needed to describe crop residues.Additional study of ERTS‐1 MSS data relating crop residues to wind and water erosion susceptibility of the soil is merited.
An Aluminum Block Digester for Plant and Soil Analysis
Authors: Gallaher R. N. , Weldon C. O. , Futral J. G. 
Published: July 2010

AbstractAlmost every institution, whether it be a university, a government agency, or a medical or industrial facility, that conducts research on and is concerned with the elemental analysis of biological material has a need for equipment to ash or acid‐digest samples. Often funds are not available with which to purchase commercial equipment and the researcher is required to be innovative and to design and engineer his own. Because of the lack of research funds and a need for soil and plant analysis equipment, this study was made to design and construct a large capacity, electrically‐heated and thermostatically‐controlled aluminum block digester for plant and soil samples. A drawing was prepared giving dimensions needed for shop‐work to be performed. A block of aluminum 10.2 cm (4 inches) thick was used. The block has a capacity of 126, 2.54‐cm (1 inch) diameter test tubes. The overall block dimensions are 10.2 cm (4 inches) thick, 35.6 cm (14 inches) wide, and 55.1 cm (21 11/16 inches) long. Electric heater strips are bolted to the block inside 1.9‐cm (¾ inch) milled slots. The temperature control sensor is a thermocouple inserted into the block and wired to the thermostat controller. The block heats almost linearly from room temperature to 240C at a rate of almost 4C/minute. The heating rate from room temperature to 375C is over 2C/minute and requires 2.5 hours heating time.
The Mechanism of Phosphate Fixation by Iron Oxides
Authors: Parfitt Roger L. , Atkinson Roger J. , Smart Roger St.C. 
Published: July 2010

AbstractInfrared spectroscopic techniques have been used to obtain a structural model for the surface reaction between iron oxides and phosphate ions. Two surface hydroxyl ions (or water molecules) are replaced by one phosphate ion. Two of the oxygen atoms of the phosphate ion are coordinated, each to a different Fe3+ ion, resulting in a binuclear surface complex of the type Fe‐O‐P(O2)‐O‐Fe. Evidence is given for phosphate adsorption producing this coordination structure on the surfaces of goethite, hematite, lepidocrocite, β‐ferric hydroxide, and amorphous ferric hydroxide gel.
Relationships Between the Hydraulic Conductance of Surface Crusts and Soil Management in a Typic Hapludalf
Authors: Falayi O. , Bouma J. 
Published: July 2010

AbstractThe effect of different soil management, in terms of soil till‐age and crop rotation, on soil crusting was investigated by applying continuous artificial rain (8.5 cm/hr) to experimental plots until steady‐state conditions were reached. Comparisons were made with bare plots subjected to natural rainfall for a period of 4 months. Significant differences in soil roughness between the plow only and the plow, disk, and harrow treatments resulted in higher infiltration and longer times to incipient runoff for the plow treatment. However, differences in surface roughness and infiltration and runoff rates were insignificant among treatments when steady‐state conditions were reached after only 2 hours. Crust conductances, measured in situ, were significantly lower in the plow, disk, and harrow treatments for the sod as compared with the continuous corn rotation. Crusts had a significantly higher conductance when formed on top of clods as compared with crusts formed between clods in the plow treatment. Conductances of crusts formed under short‐term high‐energy experimental rainfall were not significantly different from those formed under natural conditions, the latter characterized by intermittent low‐energy rainfall during a 4‐month period. However, their morphology was significantly different.
Dissolution of Illite—A Possible Mechanism of Potassium Release
Authors: Feigenbaum Sala , Shainberg I. 
Published: July 2010

AbstractThe rate of potassium aluminum, iron and magnesium release from Fithian illite in dilute salt solutions and at pH ⩾ 3, was studied. It was found that cumulative cation release was proportional to the square root of the duration of the treatment. The rate of Al release was similar to the rate of K release, whereas the rate of Fe and Mg release was about three × that of K and Al release. Since the only known mechanism for the release of the lattice cations is the dissolution of the clay, it is proposed that dissolution of the clay lattice is also the dominant mechanism by which potassium is released from the clay. Two consecutive reactions, a rapid exchange reaction and a slow first‐order reaction, explain the experimental observations.
A Thermodynamic Model for Predicting the Formation, Stability, and Weathering of Common Soil Minerals
Authors: Rai Dhanpat , Lindsay W. L. 
Published: July 2010

AbstractNumerous workers have examined the weathering products of soil minerals and have proposed empirical weathering sequences. The present paper outlines the development of a thermodynamic model that predicts in a systematic way several mineral transformations that can occur in soils.According to this model, the stability of primary minerals increases in the order: Na‐glass, K‐glass, pyroxene, analcime, anorthite, low albite, muscovite, microcline, and quartz. The stability of secondary clay minerals depends on soluble silica. At pH 6 with high silica (≃ 10‐3M) the order of increasing stability is: chlorite, halloysite, gibbsite, illite, dickite, beidellite, kaolinite, and montmorillonite; at low silica (≃ 10‐5M) the order is: chlorite, halloysite, illite, beidellite, montmorillonite, dickite, kaolinite, and gibbsite. The stability of both primary and secondary minerals increases with pH.The observed weathering of volcanic ash agrees well with the predictions of this model. The model makes use of important thermodynamic data accumulated for soil minerals and helps to pinpoint deficiencies in these data. The need to examine the kinetics of mineral transformations in soils in greater detail also becomes obvious from this model.
Hydrothermal Soils of the Crater of Mt. Baker, Washington
Authors: Bockheim J. G. , Ballard T. M. 
Published: July 2010

AbstractSoils and rocks were sampled near active steam vents in the crater of Mt. Baker, in order to determine the soil chemical and mineralogical properties associated with hydrothermal and solfataric alteration. X‐ray diffraction analysis indicated the formation of kaolinite, montmorillonite, analcime, gibbsite, and some other minerals in these materials. The soils range from very gravelly sand to gravelly loamy sand in texture, and are extremely acid (pH 1.2–2.8). These soils have low cation exchange capacity (2.7–5.8 meq/100 g), high to very high electrical conductivity (1.3 to 11.2 mmho/cm), and small amounts of free Fe, Al, and Si. Dominant water soluble ions are HSO4‐ and SO42‐, Fe2+, Al3+, H+, Mg2+, and Ca2+. Altered andesite rock and soil are depleted in Al2O3, CaO, and MgO, and locally enriched in Fe2O3.
Solute Travel‐Time Estimates for Tile‐Drained Fields: I. Theory
Authors: Jury W. A. 
Published: July 2010

AbstractA model based on papers by D. Kirkham (1949; 1958) is proposed for calculating solute travel times and effluent water quality for tile‐drained soil profiles for cases of ponded and unsaturated surface water input. Variables required for utilization of the model are drain spacing, depth of tile, depth to impermeable zone, soil porosity, and mean discharge rate over the time of study. By using dimensionless variables a characteristic travel‐time parameter is introduced which will represent a system and allow the model calculations to be summarized on a single graph. Simulations are run for cases of miscible displacement, step‐function surface solute input, and periodic surface solute input; differences between ponded and unsaturated leaching are discussed for tile systems.
Transport of Water and Heat in a Frozen Permeameter
Authors: Miller R. D. , Loch J. P. G. , Bresler E. 
Published: July 2010

AbstractTransport of water in frozen soils is probably not restricted to fluid phases. In a frozen permeameter a series‐parallel mode of transport should exist in which the ice phase may move with uniform translational velocity in a stationary pore system formed by particles having adsorbed films of unfrozen water. A microscopic model for coupled mass and heat transport would be complex, but foundations for such a model are laid in an exercise which derives direct and cross coefficients for coupled transport equations applicable to a permeameter containing a simplified (nontortuous) “soil” with uniform cylindrical channels, ice‐filled except for films adsorbed at channel walls. Temperature dependence of coefficients, assuming Newtonian shear in the film, can be modeled using standard double‐layer theory. It is shown that the resultant coefficients are relatively insensitive to temperature (film thickness) but are highly dependent on thermal conductivities of components. Identity of cross‐coefficients in this mechanical model is demonstrated. Expressions for computing phenomenological soil coefficients from coefficients measured in a practical permeameter are given, and a workable permeameter for such studies is postulated.
Stability Analysis of Infiltration
Authors: Philip J. R. 
Published: July 2010

AbstractA rigorous hydrodynamic stability analysis of the delta‐function model of infiltration is developed. Raats recently proposed as the criterion for instability that wetting front velocity should increase with front penetration. This detailed analysis, on the other hand, shows that the fundamental criterion is that the water pressure gradient immediately behind the front should oppose the flow. The two criteria agree only in the special case where five significant parameters of the system are all constant and independent of depth, or of depth to the front. The Raats criterion fails in the various more general cases with one or more of these quantities variable.Quantitative criteria are developed for various specific circumstances in which the flow may become unstable: penetration to a non‐wetting stratum; compression of air ahead of the front; redistribution following infiltration; increase of conductivity with depth.The analysis indicates a definite maximum wave number for unstable disturbances, Mcrit, and a wave number for disturbances which are amplified most rapidly, 3‐½ Mcrit. Flows in a laboratory soil column may therefore remain stable because the cross‐sectional dimensions are too small. Observed dimensions of fingers in unstable infiltration flows are consistent with the predicted wave number for maximum amplification.The study is readily extended to time‐dependent flows of two immiscible fluids in heterogeneous media. It applies also to time‐dependent flows in heterogeneous Hele‐Shaw cells.Care should be exercised in applying results for the deltafunction model to flows with gradual wetting fronts, especially when nonwetting strata are involved.
Acidification and Deacidification of Coastal Plain Soils as a Result of Periodic Flooding
Authors: van Breemen N. 
Published: July 2010

AbstractPeriodic flooding of recent coastal plain soils causes either acidification or deacidification of the surface horizons. Acidification of sulfate‐bearing “nonacid” soils (pH > 5) involves formation of FeS and partial loss of alkalinity (HCO3‐) in the flood water during the wet season, followed by oxidation of FeS to ferric oxide and sulfuric acid in the dry season. Deacidification of acid soils (pH < 4.5) takes place during flooding. This involves reduction of ferric oxides to Fe2+, the simultaneous release of adsorbed SO42‐ or hydrolysis of basic sulfates (that function as proton donor during iron reduction at low pH), followed by oxidation of dissolved FeSO4 to ferric oxide and sulfuric acid at the soil‐water interface, and removal of H2SO4 by lateral surface drainage. During soil reduction the actual pH increases and a shift from one process to the other takes place if the pH becomes high enough (4.5 to 5) for the weak acids CO2 and H2S to function as proton donors. Therefore, deacidification beyond pH 4.5 to 5 automatically invokes the release of alkalinity. Conversely, acidification to a pH below 4.5 to 5 during a dry season will be undone by deacidification in the following wet season. This explains why the surface horizons of periodically flooded acid sulfate soils and nonacid marine soils eventually attain the same pH under dry conditions. This pH is fundamentally related to the dissociation constant, the solubility and the partial pressure of CO2.
In situ Measurement of Gas Diffusion Coefficient in Soils
Authors: Lai Sung‐Ho , Tiedje James M. , Erickson A. Earl 
Published: July 2010

AbstractA method for determination of the gas diffusion coefficient of soils without disturbing the natural state of the soil was developed. The method was based on the theory of radial diffusion of a finite quantity of gas into a semi‐infinite porous medium. Needles were inserted into the soil through which O2 was injected. The change of concentration of the injected O2 was determined by gas chromatography through the same needle after increasing periods of time. A least square fit between the measured O2 concentrations and that of the theoretical values was conducted to find the best fit value of the diffusion coefficient. The diffusion coefficient determined by the proposed method was used to calculate the flux of CO2 in field soils. The flux so calculated was compared to that measured from the field with good agreement. The method was used in several different field soils and conditions to determine the diffusion coefficients.
Comparisons of Calculated and Measured Capillary Potentials from Line Sources
Authors: Thomas Adrian W. , Duke Harold R. , Zachmann David W. , Kruse E. Gordon 
Published: July 2010

AbstractThis paper is a sequel to D. W. Zachmann and A. W. Thomas' (1973) development of equations describing steady infiltration from line sources. Calculated distributions of capillary potentials are compared with those measured in a soil bin designed to model the water distribution from a subsurface irrigation system. Limitations of the steady‐state equations for predicting capillary potentials are given. A procedure for selecting lateral depth and spacing to attain a given matric flux potentials is also given.
Comparison of Field‐measured and Calculated Soil‐heat Fluxes
Authors: Kimball B. A. , Jackson R. D. , Reginato R. J. , Nakayama F. S. , Idso S. B. 
Published: July 2010

AbstractSoil‐heat fluxes calculated using DeVries' theory (1958, 1963) were compared with those experimentally determined in a field of Avondale loam at Phoenix, Ariz., on 6 days representing different seasons of the year. A fair agreement between measured and computed fluxes was obtained only after modifying the air shape factor curve and ignoring heat transfer due to water vapor movement. The omission of the latter implied that heat transfer by pure conduction was most important and that thermal and isothermal vapor fluxes exactly cancelled during the day and were insignificant at night.“Measured” thermal conductivities were also determined from the ratio of the measured heat fluxes to the corresponding temperature gradient for those times when it was unlikely that isothermal vapor movement was significant. The lack of a temperature dependence in these data, as well as the flux comparisons, strongly indicate that the theory overestimated thermal vapor movement. These data plus others in the literature indicate that an individual “calibration” of the theory for a particular soil is required before reliable predications of soil‐heat flux can be obtained.