bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pyrite and Marcasite Surface Area as Influenced by Morphology and Particle Diameter
Authors: Pugh C. E. , Hossner L. R. , Dixon J. B. 
Published: July 2010

AbstractThe morphology of massive and framboidal pyrites and marcasite extracted from lignitic cores was examined with light and scanning electron microscopes. The primary objective was to determine the surface area for these sulfide minerals. Framboidal pyrite spheres consisted of micron‐sized crystals and suggested a high surface area compared to other iron (Fe) sulfides. Specific surface space was determined using the linear form of the B.E.T. equation and N2 gas as the adsorbate.Framboidal pyrite was composed of individual microcrystals that ranged from 1 to 5 µm in diameter. Surface area of framboidal pyrite remained near 2.0 m2/g for mean diameters ranging from 150 to 60 µm but increased to as high as 4.0 m2/g for diameters between 5 and 2 µm. Marcasite spheres were 4 to 5 times larger in diameter than single framboids. Surface area of all fractions of marcasite and massive pyrite ranged from 0.2 to 0.5 m2/g. Specific surface decreased as particle size increased.
Simulated Weathering of Lignite Overburden Shales from Northeast Texas
Authors: Senkayi A.L. , Dixon J.B. , Hossner L.R. 
Published: July 2010

AbstractUnweathered overburden shale was continuously leached with water and sulfuric acid solutions (10−3 and 10−2N) for periods of up to 3 months. Clay samples from the shale were also subjected to artificial weathering by incubation in sulfuric acid solutions. Acidity resulted in increased leaching of the basic cations from the exchange complex, particularly Ca and Mg, and a decrease in percent base saturation from 100 to < 20. The more concentrated acid solutions appreciably increased release of structural cations, especially Al, Fe, and Mg. Release of Fe and Mg was mostly associated with weathering of ferromagnesian chlorite. Progressive disappearance of chlorite from clay suspensions aged in solutions of increasing acidity was observed. Differential dissolution of chlorite and smectite resulted in concentration of kaolinite and mica. The relative stability of the layer silicate minerals to acidic conditions decreased in the following order: kaolinite > mica > smectite > chlorite. Weathering of chlorite in the overburden materials is a potential source of Fe oxides in reclaimed strip‐mined lands.
Mineralogy and Chemistry of Arctic Desert Soils on Ellef Ringnes Island, Arctic Canada
Authors: Foscolos A. E. , Kodama H. 
Published: July 2010

AbstractMorphological, mineralogical, and chemical characteristics of five soil profiles derived from different parent materials have been studied on the Ellef Ringnes Island, Canadian Arctic Archipelago. The aim was to investigate weathering and pedogenesis of Arctic desert soils.Morphological, mineralogical, and chemical data of the soil horizons indicate that there is very little soil differentiation between the parent material and the top horizons. However, since the Wisconsin retreat, some 11,000 years ago, bioxidation of pyrite Thiobacillus ferroxidans has converted most of the studied soil to acid sulfate soils containing sulfate‐bearing minerals such as natrojarosite and gypsum.
On the Estimation of N‐Mineralization Parameters from Incubation Experiments
Authors: Talpaz H. , Fine P. , Bar‐Yosef B. 
Published: July 2010

AbstractAccurate prediction of nitrogen mineralization in soils requires reliable parameters which are determined in incubation experiments. The estimated values of the potentially mineralizable organic nitrogen (No) and the mineralization rate constant (k) also depend on the mathematical analysis of the incubation results. Analysis of data by other researchers (Stanford and Smith, 1972) by a nonlinear regression procedure gave estimates of No and k which differed from those obtained by a linear regression technique. Theoretical considerations show that the difference between the two techniques results mainly from the specified behavior of the error term in the mineralization rate equation. The nonlinear regression procedure is shown to be preferable to the linear regression technique.
The Thermodynamics of Ternary Cation Exchange Systems and the Subregular Model
Authors: Chu Shu‐Yuan , Sposito Garrison 
Published: July 2010

AbstractThe thermodynamic theory of ternary exchange equilibria is developed. It is shown that the analogs of well‐known thermodynamic expressions for binary exchange systems can be derived for ternary systems as well. The subregular model of ternary cation exchange systems, which was applied recently to NH4‐Ba‐La exchange on montmorillonite, is examined critically within the thermodynamic context. It is found that the subregular model for a ternary system cannot be expressed solely in terms of parameters that depend only on data obtained for binary systems, in contradiction with claims made recently in the literature. The subregular model is shown to contain one parameter that requires ternary exchange data for its evaluation. A calculation of this ternary constant for NH4‐Ba‐La exchange on montmorillonite indicated that its value was zero within experimental precision. Nonetheless, in general it must be concluded that the behavior of ternary exchange systems cannot be predicted from data on binary exchange systems alone.
Nutrient Diagnosis in Corn Grown on Hydric Dystrandepts: II. Comparison of Two Systems of Tissue Diagnosis
Authors: Escano C. R. , Jones C. A. , Uehara G. 
Published: July 2010

AbstractRecent studies suggest that the Diagnosis and Recommendation Integrated System (DRIS), which utilizes ratios of tissue nutrient concentrations rather than the concentrations themselves, consistently produces more accurate diagnoses of nutrient deficiencies and imbalances than critical concentration approaches. However, preliminary results indicated that the DRIS based on published optimum ratios of maize earleaf nutrient concentrations gave inaccurate diagnoses of N and P fertilizer responses on Hydric Dystrandepts. The objectives of this study were to evaluate several locally calibrated modifications of the DRIS and to compare their diagnostic accuracies with those of a locally calibrated critical concentration approach. The percentage of correct diagnoses [method (D) in the first paper in this series] was used to determine the diagnostic accuracy of the two approaches. Both approaches were more accurate when the critical values of nutrient concentrations or the critical values of ratios of nutrient concentrations were derived from experimental data rather than from published values. The accuracy of the DRIS approach was improved by (i) judicious selection of the high‐yielding subpopulation, (ii) selecting the critical values of DRIS indexes based on their effects on diagnostic accuracy, and (iii) using 10 rather than either 3 or 36 ratios of nutrient concentrations to calculate DRIS indexes. After calibration of both approaches, the DRIS approach was 8% more accurate than the conventional approach for diagnosis of N deficiency. The two approaches were almost equally accurate for diagnosis of P deficiency.
Estimation of Saturated Hydraulic Conductivity from Soil Morphological and Genetic Information
Authors: King J. J. , Franzmeier D. P. 
Published: July 2010

AbstractSaturated hydraulic conductivity, Ksat, was measured below the water table by the piezometer method for subsurface horizons of several Indiana soils. Lowest Ksat rates were in compact glacial till, paleosols formed in till and fragipan horizons formed in loess. Camblc and argillic horizons had intermediate rates. Highest rates were in B3 horizons formed in water‐reworked glacial till materials. For prediction purposes, data were grouped by soil texture and standard soil structure classes in one classification and by texture, origin of parent material, and kind of genetic horizon in another classification. The second grouping resulted in more homogeneous classes, but some of these classes spanned more than one order of magnitude. The proposed method for determining Ksat and using the results to estimate it for other horizons can be used by field soil scientists to obtain better estimates for many soils.
Substrate Characterization of an Experimental Marsh and Three Natural Marshes
Authors: Lindau C. W. , Hossner L. R. 
Published: July 2010

AbstractDredge material from the Gulf Intracoastal Waterway near Galveston, Tex., was used as a substrate material in the construction of an experimental intertidal salt marsh. Chemical and physical properties of dredge substrate samples at 270 sites were monitored over a 16‐month period. Cation exchange capacity (CEC), extractable phosphorus (P), total Kjeldahl nitrogen (TKN), NH4‐N, and organic matter increased from 3.0 to 7.4 meq/100 g, 24 to 96 µg P/g, 85 to 296 µg N/g, 3.0 to 9.9 µg N/g, and 0.2 to 0.5%, respectively. No significant increases in N and P were observed in the substrate due to fertilization.A separate study comparing substrate properties of the experimental marsh to three natural marshes demonstrated that organic matter, TKN, and NH4‐N concentrations in the experimental marsh were lower. Organic matter, TKN, and NH4‐N in the experimental marsh substrate averaged 0.6%, 260 µg N/g, and 5.4 µg N/g compared to 2.3%, 650 µg N/g, and 12.1 µg N/g, respectively, for the three natural marshes. Within each of the four marsh sites extreme spatial heterogeneity of chemical and physical properties was apparent.
Ammonium Orthophosphate and Ammonium Polyphosphate as Sources of Phosphorus for Potatoes
Authors: Rhue R. D. , Hensel D. R. , Yuan T. L. , Robertson W. K. 
Published: July 2010

AbstractA field experiment was initiated in 1978 to compare the effects of granular diammonium phosphate (DAP) and liquid ammonium polyphosphate (APP) on growth, nutrient content, and yield of potatoes (Solanum tuberosum L.). Two sites on a coarse‐textured Inceptisol with markedly different cropping histories were selected, one with 5 ppm P, the other with > 200 ppm P extractable with 0.05N HCl + 0.025N H2SO4. Fertilizers were banded at P rates of 0, 56, 112, and 168 kg/ha at the low P site, and 0, 24, and 48 kg/ha at the high P site. At the low P site tuber yields and tissue P concentrations were lower with APP than with DAP, while tissue concentrations of Ca, Mg, Mn, and Zn were higher with APP. At the high P site, tuber yield and top dry weight were not affected by P source, but tissue Ca and Mg were higher and tissue P lower with APP.In 1979 and 1980, DAP and APP were applied at a rate of 56 kg P/ha at the low P site. Tissue levels of P again were lower while those of Ca, Mg, Mn, and Zn were higher with APP both years. Tuber yields were lower with APP in 1980.In 1980, DAP and APP were applied at the high P site at the same rates used in 1978. Yields were unaffected by P source but tissue P was lower and tissue Zn was higher with APP.Extractable P levels in soil samples taken after harvest were higher in 1978 with APP. With time, extractable P declined for both sources, and by the following crop season, there were no differences in extractable P due to P source. Extractable P again was higher in 1980 where APP had been applied.The results showed that availability of fertilizer P for winter‐planted potatoes was less with APP than with DAP. Less P was found in tops of potatoes with APP regardless of the level of available soil P. Tuber yields, however, were less affected by P source, and the data suggest that most years' tuber yields will not be different with these two sources except on soil with very low levels of available P. Application of APP also resulted in increased uptake of Ca, Mg, Mn, and Zn by potatoes.
Soil Water Content by Microwave Drying: A Routing Procedure
Authors: Gee G. W. , Dodson M. E. 
Published: July 2010

AbstractA routine procedure was established for determining soil water content by microwave drying. The procedure requires small, 20‐gram soil samples heated for a 20‐min period at full power (600 to 650 W) in a household‐type microwave oven. Using this procedure, consistent agreement (within 0.5 wt%) was obtained between microwave and electric oven drying for soil materials ranging from quartz sands to fine silts and clays, with water contents ranging from air‐dry to saturation and with organic matter ranging from 0 to > 20 wt%.
Copper(II) and Iron(III) Complexation by the Carboxylate Group of Humic Acid
Authors: Boyd Stephen A. , Sommers Lee E. , Nelson Darrell W. 
Published: July 2010

AbstractInfrared (IR) spectroscopy, between 2,000 and 1,000 cm−1, was used to identify the mode by which carboxylates of a soil humic acid (HA) complexed Cu2+ and Fe3+. Carboxylic acid groups of HA (R‐COOH) were converted to carboxylates (R‐COO‐) by forming coordinate bonds with Cu2+ and Fe3+. The separation Δ of the antisymmetrical and symmetrical stretching vibrations of R‐COO‐ was obtained from the IR spectra of the metal‐HA complexes. The Δ values for the metal‐HA complexes were significantly larger than the corresponding reference value of Δ for uncomplexed ‐COO‐, demonstrating that R‐COO‐ formed a unidentate complex (i.e., a single M‐O bond) with Cu2+ and Fe3+. The formation of bidentate or bridging complexes between R‐COO‐ of HA and Cu2+ or Fe3+ was not observed.
Spatial Variability of Soil Hydraulics and Remotely Sensed Soil Parameters
Authors: Lascano R. J. , Van Bavel C. H. M. 
Published: July 2010

AbstractThe development of methods to correctly interpret remotely sensed information about soil moisture and soil temperature requires an understanding of water and energy flow in soil, because the signals originate from the surface, or from a shallow surface layer, but reflect processes in the entire profile. One formidable difficulty in this application of soil physics is the spatial heterogeneity of natural soils. Earlier work has suggested that the heterogeneity of soil hydraulic properties may be described by the frequency distribution of a single scale factor. The sensitivity of hydraulic and energetic processes to the variation of this scale factor is explored with a suitable numerical model. We believe that such an analysis can help in deciding how accurately and extensively basic physical properties of field soils need to be known in order to interpret thermal or radar waveband signals. It appears that the saturated hydraulic conductivity needs to be known only to its order of magnitude, and that the required accuracy of the soil water retention function is about 0.02 volume fraction. Furthermore, the results may be helpful in deciding how the total scene or view field, as perceived through a sensor, is composed from the actual mosaic of transient soil properties, such as surface temperature or surface soil moisture. However, the latter proposition presupposes a random distribution of permanent properties, a condition that may not be met in many instances, and no solution of the problem is apparent.
Interflow of Water through a Sloping Soil with Seepage Face
Authors: Ahuja L. R. , Ross J. D. 
Published: July 2010

AbstractA theoretical analysis of interflow pathways, source areas, and rates is presented for saturated, steady, and homogeneous conditions. Investigated were the effects of slope length to soil depth ratio, soil slope, slope‐of the seepage face, boundary condition at the upper end of the slope, leakiness of the base, and of ditch water covering the seepage face. Two regions of interflow could be distinguished: (i) flow through the main body of the soil (region 1), and (ii) flow from infiltration near the seepage face (region 2). For soil on an impermeable base, all the interflow water in region 1 entered the soil through a small area near the upslope end and flowed parallel to the slope before seeping out of the face near the base. For a slope length to soil depth ratio of 10 or larger, this part of interflow could be approximated as one‐dimensional flow with hydraulic gradient equal to the sine of the soil slope angle. Presence of a seepage face at the lower end of the slope caused considerable additional infiltration to contribute to interflow, entering from a distance near the face of about 2.5 times the depth of soil (region 2). This flow increased as the face slope (with respect to the base) increased, but was not influenced by slope length and was influenced in a minor way by soil slope. When the ditch water covered the seepage face completely, the infiltration in region 2 was prevented. For soil on a leaky base with leakage rate as low as 1/100th the hydraulic conductivity of the soil, all the water entering upslope of a short distance from the seepage face flowed downward into the leaky base. The slope length and soil volume traversed by interflow were reduced drastically. The boundary between the interflow and leakage flow regions could be approximated by a straight line of slope v/K tan ω passing through the origin, where v is the leakage rate, K is the hydraulic conductivity of soil, and ω is the soil slope angle.
Trace Metal Chemistry in Arid‐zone Field Soils Amended with Sewage Sludge: I. Fractionation of Ni, Cu, Zn, Cd, and Pb in Solid Phases
Authors: Sposito Garrison , Lund L. J. , Chang A. C. 
Published: July 2010

AbstractThe surface horizons of two arid‐zone field soils that had received amendments of either liquid or dried, anaerobically digested sewage sludge for 4 years were sampled to determine the forms of selected trace metals in the solid phase. The soils had been amended with sludge twice annually at rates of 0, 22.5, 45.0, or 90.0 tons · ha−1 · year−1. Barley and sorghum had been grown on the soils in randomized experimental plots. The soil samples were analyzed for total Ni, Cu, Zn, Cd, and Pb and were fractionated by sequential extraction to estimate the quantities of these metals in “exchangeable,” “sorbed,” “organic,” “carbonate,” and “sulfide” forms.The total contents of the five metals in the two field soils were governed by the total content of the metals in the sludges applied and by the rate of sludge application. The accumulation of metals in the surface horizons of field plots receiving liquid sludge was less than that in the plots receiving composted sludge, possibly because of a lesser reduction in soil bulk density resulting from sludge applications. The percentage of the total metal content in exchangeable and sorbed forms was very low, averaging between 1.1 and 3.7% for all of the metals regardless of the type of soil, the form of sludge applied, or the sludge application rate. The application of sludge tended to reduce the sulfide fraction and to increase the organic and carbonate fractions of all five trace metals. At the highest rate of sludge application, the predominant forms of the metals were: Ni, sulfide; Cu, organic; and Zn, Cd, and Pb, carbonate.
Field Measurement of Denitrification: III. Rates During Irrigation Cycles
Authors: Rolston D. E. , Sharpley A. N. , Toy D. W. , Broadbent F. E. 
Published: July 2010

AbstractAbsolute amounts and rates of denitrification from a Yolo loam field profile at Davis, Calif., were studied in relation to the influence of irrigation frequency and soil incorporation of crop residue. Two different carbon (C) treatments were established by using plots to which no crop residues had been incorporated within 1 year prior to the experiment and plots to which 10 metric tons ha−1 of chopped barley straw were incorporated into the top 10 cm of soil 2 months prior to fertilization. The same total amount of water was applied at frequencies of three irrigations per week, one irrigation per week, and one irrigation every 2 weeks to areas cropped with perennial ryegrass. Fertilizer was applied as KNO3 (≅ 285 kg N ha−1) enriched with 56 to 60% 15N to 1‐m2 plots. The surface flux of denitrification gases was measured from the accumulation of nitrous oxide (N2O) and 15N2 beneath airtight covers placed over the soil and from measurements of N2O using the acetylene (C2H2) inhibition method. Small fluxes of denitrification gases were measured in this well‐drained alluvial soil under normal cyclic applications of irrigation water. Total denitrification ranged from 0.7 to 5% for the least frequently irrigated (no straw) and most frequently irrigated (straw) plots, respectively. Surface denitrification gas fluxes were largest after the first irrigation, decreased to near zero values within 1 or 2 days after each irrigation, and generally decreased for subsequent irrigations. The amount of N2 produced was much greater than N2O. The nitrous oxide flux at the soil surface varied between 5 and 27% of the total denitrification over a 40‐ to 50‐day period. Nitrous oxide mole fractions tended to be smallest immediately after irrigation and increased as the soil water redistributed and the soil profile became less anoxic. The irrigation frequency of three irrigations per week gave higher soil NO3‐ concentrations within the root zone of the crop than those of the other two frequencies. Thus, frequent, small irrigations may result in less leaching losses than infrequent, large irrigations.
Erodibility Indices Compared to Measured Values of Selected Trinidad Soils
Authors: Lindsay J. I. , Gumbs F. A. 
Published: July 2010

AbstractThe most suitable erodibility index for tropical soils has not been determined. This study was therefore carried out with 10 selected Trinidad soils to compare three erodibility indices previously used with soils in different parts of the world. The erodibility of the soils was determined by the USDA Erodibility Nomograph, the Australian Erodibility Index, and the Modified Raindrop Technique and their suitability evaluated by comparison with the erodibility measured directly on four of the 10 soil types in the field.The USDA Erodibility Nomograph correctly predicted the erodibility class of the four soil types; the Australian Index in two of the four soil types; and the Raindrop Technique did not prove to be a suitable method. The number of drops required to break the soil aggregate in the Raindrop Technique depended on the wetting and drying history of aggregate. The erodibility of the four soil types determined by the Nomograph were all classified as slight.
Ammonia Volatilization and Soil Nitrogen Changes after Urea and Ammonium Nitrate Fertilization of Pinus Taeda L.
Authors: Craig Joseph R. , Wollum A. G. 
Published: July 2010

AbstractFrom 3.9 to 13.1% of the nitrogen (N) was lost to the atmosphere when 200 kg/ha of N as (NH2)2CO were applied to an undisturbed forest soil during each of the four annual seasons. There were no measurable losses from a comparable NH4NO3 treatment. The majority of the loss occurred within the first 2 weeks after fertilizer application. During this time volatilization of NH3 from the (NH2)2CO‐amended soils appeared to depend more on moisture in the soil and time and amount of precipitation after fertilizer application than on season of fertilizer application. Conditions of light precipitation providing adequate moisture for (NH2)2CO hydrolysis but insufficient to leach the (NH2)2CO resulted in the greatest NH3 losses. Heavy precipitation leached the urea or NH3 deeper into the soil profile where it was retained. Although differences were not significant among seasons, winter loss < fall < summer ≃ spring. Precipitation trends and seasonal temperature differences may be responsible for these differences.Ammonium‐N from (NH2)2CO remained in the forest floor and top few centimeters of mineral soil. In contrast, the NH4+ produced by the ionization of NH4NO3 was carried deeper into the soil profile.