bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromate Adsorption on Goethite: Effects of Aluminum Substitution
Authors: Ainsworth C. C. , Girvin D. C. , Zachara J. M. , Smith S. C. 
Published: July 2010

AbstractThe adsorption of CrO2‐4 to goethites varying in specific surface area and Al substitution was measured over a range in pH, sorbate and sorbent concentrations and ionic strength. The α‐(Fe, Al)OOH exhibited a lower pH50 (the pH at which 50% adsorption occurs) for the CrO2‐4 at all adsorbate concentrations (6 × 10−6 to 5 × 10−4 M CrO2‐4) than did the two α‐FeOOH samples; this difference could not be attributed to either variations in CrO2‐4 adsorption density or sorbent PZC. The overall proton coefficient (n), calculated from adsorption data for 5 × 10−7 M CrO2‐4, was identical for the two α‐FeOOH samples despite differences in the physical nature and sorbate‐to‐surface site ratio of the two samples. The observed n for the α‐ (Fe, Al)OOH system was larger than the n for the pure goethite systems. These data suggest that differences in the acid‐base properties and interaction with the background electrolyte for the Fe and Al sites affect the overall proton coefficient and CrO2‐4 adsorption on the substituted surface when compared to the pure surface. The surface coordination constants for the Triple Layer Model (TLM) were derived for CrO2‐4 adsorption on the α‐FeOOH solids using the FITEQL computer code. Using these and other TLM constants from the literature, adsorption on all three goethite samples was quantitatively simulated over a range in solute and sorbent concentrations, pH and ionic strength. The successful simulation of CrO2‐4 sorption onto α‐(Fe, Al)OOH required the use of a two‐site model which included the ionization and electrolyte complexation reactions of both Fe and Al sites. Site densities of Fe and Al were taken to be proportional to the mole fraction of each in the α‐(Fe, Al)OOH solid. However, the interaction of the CrO2‐4 species with the Al sites was not required to quantitatively describe the adsorption edge since the log K for the dominant FeOH+2‐HCrO‐4 species is three orders of magnitude greater than the ‐CrO2‐4 or ‐HCrO‐4 on Al sites.
A Method To Secure, Leach, and Incubate Undisturbed Soil Cores
Authors: Myers R. G. , Swallow C. W. , Kissel D. E. 
Published: July 2010

AbstractAccurate N fertilizer recommendations depend upon knowing the amount of soil organic N that is mineralized. A promising method developed by Stanford and Smith (1972) to predict N mineralized with disturbed soil samples allows for adjustment in the mineralization rate due to field variations in soil temperature and water. Recent work has indicated that undisturbed soil cores could more closely represent the field soil and its mineralization characteristics. Therefore, a method was needed to secure undisturbed soil cores in a container that would maintain their field integrity and allow them to be incubated and leached periodically as per Stanford and Smith's technique. The method utilizes a 6.3‐cm i.d. polyvinyl chloride (PVC) compression coupler to hold an undistrubed soil core. The undisturbed soil sampling device consists of a lever and anchor system, which can put pressure on a soil cutter and adjustment bar to force soil into the coupler. After a soil core is obtained from the field, the coupler is adapted so that the soil within can be leached, equilibrated to a constant water potential, and incubated. In extensive sampling of 19 soils that varied widely in clay and organic C contents, samples could be obtained rapidly if soil was near field capacity. This method of sampling and incubation was relatively inexpensive and simple, and produced data of cumulative N mineralized with time that could be fit with a first‐order kinetic model.
Mineralogical and Chemical Characteristics of Adirondack Spodosols: Evidence for Para‐ and Noncrystalline Aluminosilicate Minerals
Authors: Johnson M. G. , McBride M. B. 
Published: July 2010

AbstractLittle is known about the para‐ and noncrystalline inorganic mineral phases in the soils of the northeastern USA. This research was conducted to obtain information on the chemistry, mineralogy, and reactivity of these materials in representative soils from this region. Using a combination of classical and nonclassical chemical and mineralogical methods, four Spodosols from Adirondack State Park, New York, were characterized. The principal clay‐sized layer silicates identified included: kaolinite, hydroxy‐interlayered vermiculite, and hydroxy‐interlayered smectite. These tended to be concentrated in E horizons. Minor amounts of clay‐sized feldspar and mica were also identified. Para‐ and noncrystalline materials were the most abundant constituents of the <2‐µm clay from B and C horizons. Up to 720 g/kg of the <2‐µm B horizon clay was para‐ or noncrystalline materials. In contrast, these materials, on average, accounted for only 65 g/kg in the E horizon <2‐µm clays. Reaction with NaF indicated that these materials have very high surface reactivities. Infrared spectrophotometry, Mössbauer, electron microscopy, and selective dissolution studies were used to characterize the <2‐ and <0.5‐µm clay fractions. Imogolite‐like materials, so called because of the lack of a characteristic imogolite doublet near 1000 cm−1 in the infrared, indicating poor development in the imogolite c‐axis direction, were identified in the <0.5‐µm clays from B and C horizons. Characteristic imogolite tubular morphology was not observed by electron microscopy. Mössbauer experiments indicated the presence of microcrystalline goethite and ferrihydrite; electron microscopy confirmed their presence. Para‐ and noncrystalline aluminosilicates appear to be a significant component of these soils; their high surface reactivities may have large influence on the chemical reactivity and physical characteristics of these soils.
Vegetation Indicators of Organic Soil Properties in Minnesota
Authors: Swanson David K. , Grigal David F. 
Published: July 2010

AbstractVegetation is the main surface indicator for properties of organic soils. The presence of certain taxa of common vascular plants can be used to classify sites as oligotrophic (surface soil water pH < 4.4), mesotrophic (pH 4.4–5.6), or eutrophic (pH > 5.6) with about 90% accuracy. The significance of trophic status to plants and the ease with which it can be mapped from native vegetation suggest that trophic phases of certain organic soil mapping units should be recognized in soil survey. Vegetation structure (the basal area of coniferous and hardwood trees, and the percent cover of shrubs, herbaceous plants, and mosses) and pH are weakly related to the degree of peat decomposition, the basis for suborders of organic soils in Soil Taxonomy. Extensive field sampling is therefore necessary to map taxonomically based units of Histosols.
Arthropic Epipedons in the Tombigbee Valley of Mississippi
Authors: Pettry D. E. , Bense J. A. 
Published: July 2010

AbstractAnthropic epipedons resulting from prolonged habitation were characterized in midden mounds of natural fluvial origin in the Tombigbee River Floodplain of Mississippi. Radiocarbon ages ranged from 300 yr before present (YBP) in surface layers to 7000 (YBP) in deeper zones of the dark‐colored epipedons. The loamy epipedons ranged from 1‐ to 1.5‐m thick and contained 0.6 to 3% organic C and 1 to 5% charcoal fragments. Munsell hues were 5YR and 7.5YR with values and chromas of 3 or less due to particle coatings of humic materials that promoted granular structure and H2O repellency. Base saturation ranged from 24 to 73% with pH levels one unit higher than adjacent off‐site soils. Calcium/Mg values exceeded 10:1 due to Ca enrichment. Total N decreased with depth and C/N ratios exceeded 30:1 due to C accumulation and N depletion. Phosphorus extracted with 1% citric acid exceeded 250 mg kg−1 in the anthropic epipedons and readily distinguished the habitation sites from adjacent soils. Nonoccluded‐P and occluded‐P were dominant P forms with lesser organic‐P and Ca‐P.
Ferro‐Humic Podzols of Coastal British Columbia: I. Morphology, Selected Properties, and Classification
Authors: Sanborn P. , Lavkulich L. M. 
Published: July 2010

AbstractFerro‐Humic Podzols (Cryorthods and Cryochrepts) of loamy texture on western Vancouver Island, British Columbia, have distinctively high organic matter and sesquioxide concentrations and limited albic horizon development. Their properties and taxonomic status were evaluated in relation to Spodosols of other maritime regions. Oxalate‐extractable Al concentrations (10–70 g kg−1) are comparable to those in podzolized soils containing tephra. Free Fe concentrations exceed 35 g kg−1 in most Bhs horizons, with approximately half in crystalline forms. Oxalate‐extractable Si concentrations suggest a substantial allophane content in some Bhs horizons. Maximum C concentrations (110–180 g kg−1) occur at 0.5‐ to 2.0‐m depth above root restricting layers or in channel‐like features initiated by tree roots. The maximum organic C content (170 g kg−1) allowed by the Canadian classification for mineral soil horizons may be too restrictive. Clay concentrations are high enough to exclude some pedons of podzolic morphology from the Spodosols of the U.S. system of soil taxonomy. Adoption of a required (Alp + Fep)/clay ratio lower than the current minimum of 0.2 for spodic horizons in the U.S. system would provide a more realistic classification of these soils.
Aluminum Release from Solid‐Phase Components of Forest Soil Leached with Citric Acid
Authors: Jersak Joseph M. , McColl John G. 
Published: July 2010

AbstractThe solubility of solid‐phase Al pools within size fractions of a forest soil A horizon was evaluated using aqueous citric acid to determine the rates and cumulative amounts of Al released over time. Particle‐size fractions were also characterized by the nature and sizes of various solid‐phase Al pools present. The magnitude of particular Al pools explained the rate of Al release over time. Sizes of organically bound Al pools (quantified by Na pyrophosphate extraction) were similar to those amounts of Al rapidly released in the early stages of citric acid leaching, indicating that organically bound Al was the most soluble of the solid‐phase Al pools. The steady, but slower, subsequent release of soil Al is attributed to solubilization from primary and secondary crystalline lattice minerals. Results reaffirm the use of Na pyrophosphate extraction as a method for quantifying reactive solid‐phase soil Al pools because of its ability to extract a unique and reactive Al pool from a range of soil particle sizes.
Nitrogen Transformations in Soils Previously Amended with Sewage Sludge
Authors: Boyle Michael , Paul E. A. 
Published: July 2010

AbstractThis short‐term (10‐d) incubation experiment established the rates of nitrogen (N) transformations occurring in sludge‐amended and nonamended soil. Utilizing a nitrification block (C2H2) with (15NH4)2SO4, first‐order rate constants were calculated for N immobilization, ammonification, nitrification, and denitrification. These rate constants were compared to values obtained after a long‐term (87‐wk) incubation performed on soils sampled from the same field plots. The short‐term rates of ammonification were still higher than the controls 4 yr after the last sludge addition. Sludge applications over an 8‐yr period (180 Mg ha−1 yr−1) reduced soil nitrification potential compared to the controls when spiked with 15N. Denitrification did not cause a significant loss of N during either a short‐ or long‐term incubation period. The microbial biomass in the sludge‐amended soil contained more N, which resulted in a microbial C/N ratio of approximately 4:1 vs. 5:1 for the controls. Initial (short‐term) N immobilization rate constants were 0.43 for the sludge‐amended and 0.35 for the nonamended soil.
Characterization of Humic Acid from No‐Tilled and Tilled Soils Using Carbon‐13 Nuclear Magnetic Resonance
Authors: Stearman G. K. , Lewis R. J. , Tortorelli L. J. , Tyler D. D. 
Published: July 2010

AbstractChemical composition of humic acids is important due to their reactivity with soil‐applied pesticides and fertilizer amendments. Humic acids from continuously (7 yr) no‐tilled and tilled cotton, corn, and soybean plots in West Tennessee were characterized by 13C‐NMR from soils sampled at various depths. Humic acids were extracted with dilute NaOH solution and purified with KOH‐KCL and HCL‐HF solution, respectively. NMR solution spectra generated on a Jeol FX 90Q spectrometer (Jeol Co., Tokyo, Japan) were divided into six regions (0–40, 40–62, 62–105, 105–150, 150–170, and 170–190 ppm) and peak areas compared. Humic acid composition differed by soil depth and crop. Small differences were observed between tillage systems. Aliphatic and aromatic carbons ranged from 48 to 65% and 25 to 40% of total peak area, respectively. Carboxyl groups of humic acids as determined by 13C‐NMR ranged from 9 to 13%. Humic acids extracted from those soils containing larger amounts of C (surface no‐tilled treatments) had greater aliphatic to aromatic ratios, perhaps due to earlier stages of decomposition.
Strength Analysis of Fragipans in Some Loess‐derived Soils in Louisiana
Authors: Inman B. L. , Bryant R. B. , Hudnall W. H. 
Published: July 2010

AbstractThe objective of this study was to quantify the strength characteristics of fragipans found in selected loess‐derived soils in northeastern Louisiana. Three study sites were selected on the Macon Ridge, which is blanketed by a Peoria loess. Two sites were selected on the Bastrop Ridge, which is covered by a pre‐Peoria loess. The unconfined compression (UC) test was used to quantify the strength characteristics of (i) undisturbed fragipan material taken at field moisture, (ii) remolded fragipan material equilibrated to the same moisture content and packed to the same density as the undisturbed samples, and (iii) oven‐dried undisturbed fragipan samples. A range of strength occurred among the undisturbed samples due to natural fabric differences. Remolded samples had lower strengths compared to the undisturbed samples. In general, higher sensitivity values for fragipan horizons from the Macon Ridge sites indicated that rigidity in these fragipan horizons is derived in part from binding agents. Low sensitivity values measured on fragipans from the Bastrop Ridge sites indicated that cohesive binding agents have little effect in providing rigidity for these fragipan horizons. Dried undisturbed fragipan material exhibited strength values a full order of magnitude greater than those measured on samples tested at field moisture contents. Results indicate that the fragipans in soils developed in older loess deposits on the Bastrop Ridge have a lower component of strength derived from interparticulate binding agents than those fragipans in soils developed in the younger loess deposits on the Macon Ridge.
A Differential Scanning Calorimetry Evaluation of Quartz Status in Geogenic and Pedogenic Environments
Authors: Bartenfelder D. C. , Karathanasis A. D. 
Published: July 2010

AbstractTwelve quartz samples of geologic and soil materials were investigated by differential scanning calorimetry (DSC) to evaluate the effects of origin, crystal deformation, depositional environments, and weathering conditions on the α‐β inversion temperature, enthalpy of inversion (ΔH), and activation energy (Ea) characteristics of quartz. The 50‐ to 20‐µm particle size fraction was found to be the most suitable for thermal and x‐ray analyses. There was little variation (<2 °C) in the inversion temperature of quartz in the studied samples, which appeared to depend on apparatus and conditions. The ΔH of inversion demonstrated more sensitivity than inversion temperature, to structural substitutions or deformations, with values ranging from 1.70 to 5.86 J/g. The igneous and metamorphic samples had the highest, whereas the soil samples had the lowest ΔH. The use of apparent activation energies (Ea) showed the most promise in distinguishing the materials with respect to quartz origin, environment of deposition and extent of weathering. Activation energies were higher in igneous than metamorphic materials, decreased with age of deposit in the sedimentary materials, and generally decreased with extensive weathering of soil materials with some dependence on material type. The data suggest that Ea values may represent the integrated effect of geothermal, geogenic and pedogenic environments on the quartz structure.
Micromorphology and Mineralogy of Illuviated Clay in a Davidson Soil
Authors: Goenadi Didiek H. , Tan Kim H. 
Published: July 2010

AbstractClay illuviation was studied in a highly weathered soil of the Southern Piedmont by macro‐ and micromorphological techniques. Five pedons of a Davidson soil (Rhodic Paleudult) were sampled from four counties for preparation of thin sections and analysis of soil matrix, illuviated clay and argillans. The related distribution pattern of the soil fabric in the epipedon was different than that in the argillic horizon or saprolite. A single‐spaced porphyric fabric was found in the A horizon, which had no illuvial clays. The argillic horizon exhibited an open‐spaced porphyric fabric with illuvial clay ranging in concentrations from 2.4 to 5.6%. A double‐spaced porphyric fabric was noticed in the saprolite, which contained 1.4% illuvial clay. X‐ray diffraction analysis of clays in the soil matrix vs. argillans showed strong evidence for kaolinite as the major mineral eluviated from the upper horizon. The data also suggested that, in the argillic horizon, kaolinite was formed in situ through alteration of K‐feldspar minerals. The relatively high contents of kaolinite and iron‐oxide minerals, together with the presence of prominent argillans in the argillic horizons, indicated that the soil has undergone an intensive weathering and leaching process.
Influence of Copper or Cadmium on Soil Potassium Availability Properties
Authors: Yang Jae E. , Skogley Earl O. 
Published: July 2010

AbstractThe objective of this research was to determine the nature and extent of increased soil levels of Cu or Cd on K availability properties. Bozeman silty clay (Typic Argiborolls) samples were equilibrated at soil water potentials of −33 or −100 KPa, at temperatures of 5 or 20 °C for 3 or 14 d after additions of three levels of K and three levels of Cu or Cd. Soil solution was extracted by an immiscible liquid displacement technique. The activity of Ca, Mg, and K in soil solutions were increased by Cu or Cd additions (aCa > aMg > aK). The ratio of K to Ca + Mg (K intensity) was decreased by Cu or Cd additions when no K was applied, but increased at high levels of K addition. Soil temperature and water potential interacted with Cu or Cd additions to alter cation activities. Soil K buffer capacity was decreased by Cu or Cd additions. Increasing addition of K increased the proportion of K in both exchange and solution phases, at the expense of both Ca and Mg. Increasing additions of Cu or Cd decreased the fractional saturation of K and Mg, but increased that of Ca in the solution phase, with the reverse influence being exhibited on the exchange phase. Results indicate that Cu had a stronger influence than Cd (at equal rates of addition) on soil properties which regulate K availability.
Anion Exchange Chemistry of Middle Atlantic Soils: Charge Properties and Nitrate Retention Kinetics
Authors: Toner C. V. , Sparks D. L. , Carski T. H. 
Published: July 2010

AbstractThe negative impact of nitrate (NO3) on groundwater supplies has sparked a great deal of interest and concern in recent years, particularly in areas where coarse‐textured soils abound. In light of this concern, the anion exchange chemistry of eight soils from the Middle Atlantic region was studied with particular emphasis on NO3 retention and kinetics. The soils were chosen to encompass a range of physicochemical and mineralogical properties and were extensively characterized. Anion exchange capacity (AEC) was determined on Cl‐saturated samples by desorption of Cl with SO4. Anion exchange capacity ranged from 0 to 1.35 cmolc kg−1 for the eight soils and was found to parallel increases in clay and Fe oxide contents in the soil profiles. Point of zero salt effect (PZSE) values were determined by potentiometric titration with 0.001, 0.01, and 0.1 M NaCl as the indifferent electrolyte. These were of little value in predicting the development of AEC for the soils. The kinetics of NO3 adsorption and desorption were studied using a stirred‐flow reaction chamber and a first‐order reaction best described the data. Nitrate adsorption was found to be completely reversible, indicating a simple electrostatic retention mechanism. The effect of pH and NO3 concentration on cumulative NO3 adsorbed (CNA) and on NO3 adsorption kinetics was also studied. The CNA was found to increase with a decrease in pH below 5.5 and to increase with increasing NO3 concentration. The latter indicated an increase in competitiveness by NO3 for positively charged sites.
Temporal Relations of Phosphorus Fractions in an Oxisol Amended with Rock Phosphate and Thiobacillus thiooxidans
Authors: Muchovej Rosa M. C. , Muchovej J. J. , Alvarez V. V. H. 
Published: July 2010

AbstractLow‐grade phosphate rock plus elemental S were added to an oxisol in combination with organic matter (OM) and/or Thiobacillus thiooxidans to study the change in P fractions with time and then study availability of P solubilized. The addition of any amendment caused a significant increase in Al‐bound P. These values remained stable during the 7‐wk incubation period. Soluble P and OM‐bound P peaked within 3 wk and then decreased during the remaining period. The addition of T. thiooxidans plus S caused a rapid drop in soil pH to levels below 4.0 and a concurrent increase in P levels in the soil. After incubation, lime was added to the soils and sorghum grown for 30 d; even though, no additional P was incorporated. Solubilized P was sufficient for plant growth and dry matter produced by plants in soil amended with T. thiooxidans plus OM was similar to that of plants grown in soil amended with superphosphate.
Response of Irrigated Corn to Sulfur Fertilization in the Atlantic Coastal Plain
Authors: Kline J. S. , Sims J. T. , Schilke‐Gartley K. L. 
Published: July 2010

AbstractAccurate prediction of yield response by corn (Zea Mays L.) to S fertilization on the coarse‐textured soils of the Atlantic Coastal Plain requires information on availability and persistence of subsoil SO4‐S, potentially mineralizable soil S, and S added in irrigation and precipitation. A 3‐yr study was conducted with irrigated corn on four soils possessing characteristics commonly associated with S deficiency. A factorial combination of S application rate (0, 33, 67, 101 kg ha−1) and method (single broadcast at planting, split) was used. Grain yield, and S concentrations and N/S ratios of early whole plants (EWP) and ear leaves (EL) were determined. Extractable SO4‐S (0–100 cm) levels and inputs of S from irrigation and precipitation were measured in each year; mineralizable S in Ap horizons of all soils was determined by two incubation methods (leached and nonleached). Although application of S generally increased plant S concentrations, significant yield increases occurred in only three of the 12 site‐year combinations. Critical values for S and N/S, based on combined data from responsive sites, were 2.1 and 1.6 g S kg−1 and 18.7 and 20.3, for EWP and EL, respectively. Lack of yield response was attributed to subsoil SO4‐S, (average, 0–100 cm = 170 kg S ha−1, mineralizable S (average = 80 kg ha−1, leached method) and S contained in irrigation or precipitation (annual average = 7.5 kg ha−1). Yield increases obtained at the most responsive site may have been caused by increased immobilization of S, due to no‐tillage management, the presence of a physical barrier to root penetration at 40 to 60 cm, or subsoil Al. Successful prediction of corn response to S fertilization in Coastal Plain soils will require a comprehensive program that combines subsoil sampling and selective plant analysis, concentrated on sites identified as potentially responsive based on soil properties.