bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impacts of Acid Atmospheric Deposition on Woodland Soils in the Netherlands: III. Aluminum Chemistry
Authors: Mulder J. , van Grinsven J. J. M. , van Breemen N. 
Published: July 2010

AbstractAnnual element budgets for three acidic oak‐birch (Quercus robur L.‐Betula pendula L.) woodland soils in the Netherlands indicate high inputs of atmospheric (NH4)2SO4 (2.35–3.45 kmol NH4 ha−1 yr−1). Nitrogen transformations lead to strong acid inputs of 3.0 to 7.5 kmolc ha−1 yr−1 in these soils, which are neutralized primarily by solubilization of Al in the surface 20‐cm mineral layers (3–7 kmolc ha−1yr−1). We hypothesize that Al was relatively important in neutralizing strong acid inputs, due to the high acid loading and the low content of base cations. At the low pH (pH 3.27–4.26) dissolved Al in the mineral soil was mainly in aquo‐Al3+ form. Highest Al concentrations (up to 4 molc m−3) were reached in summer and coincided with high NO‐3 concentrations. In winter and spring, the export of Al with drainage water peaked and solute concentrations decreased. All Al mobilized in the surface layers of soil A was retained below the 40‐cm depth, probably due to cation exchange, since below this depth base saturation increased. In the deeper horizons of soils B and C, immobilization of Al was less, probably because base saturation was low. All subsoil solutions were undersaturated with respect to gibbsite and near equilibrium with jurbanite. Formation of jurbanite is unlikely, however, because mass balance calculations do not indicate net SO4 retention.
Interpretation of Alkylammonium Characterization of Soil Clays
Authors: Laird D. A. , Scott A. D. , Fenton T. E. 
Published: July 2010

AbstractThe alkylammonium method of characterizing the charge of layer silicates has recently been applied to soil clays containing mixed mineral assemblages. Various sharp, low‐angle x‐ray diffraction (XRD) peaks (e.g., 2.5 nm for tetradecylammonium‐treated samples) have been attributed to vermiculite or high‐charge smectite. To the degree that alkylammonium cations can replace interlayer K+, however, the observed low‐angle peaks may represent K+‐depleted soil illite as well as vermiculite. This hypothesis was tested by treating two reference illites with alkylamine hydrochlorides. The treated illites exhibited low‐angle XRD peaks similar to those observed in the soil clays. Moreover, the occurrence of these low‐angle peaks coincided with the release of K+ from the illites. Similarly, the alkylamine hydrochloride treatments for layer‐charge determinations released as much as 49% of the K+ from a soil clay. These data clearly show that the alkylammonium method can expand soil illites to give low‐angle XRD peaks, which may be misinterpreted as evidence of soil vermiculite.
Settling and Flocculation Value of Sodium‐Montmorillonite Particles in Aqueous Media
Authors: Keren R. , Shainberg I. , Klein Eva 
Published: July 2010

AbstractThe effect of pH, particle size, and clay concentration on the flocculation value (FV) and the settling rate of Na‐montmorillonite in dilute suspension was studied in solution of various NaCl concentrations. Flocculation values increased with increasing pH, being 10, 13, 31, and 44 mmol dm−3 of NaCl at pHs 5, 7.5, 8.5, and 9.8, respectively. The final gel volume of the samples at all pHs was high (0.35 < gel volume < 0.49 m3 kg−1), and the corresponding thickness of the water film associated with the clay surface was approximately 500 nm. The high gel volume indicates that a three‐dimensional “card‐house” structure was formed. The presence of a negative charge on the broken edges at pH 9.8, the high FV (44 mmol dm−3 NaCl) and the high gel volume suggest that an open structure with a face‐to‐face association predominates. Face‐to‐face association between two platelets may take place at surfaces having either a lower or higher specific charge density than the average montmorillonite value of 0.117C m−2. At pHs equal or below the point of zero charge of the edges, edge‐to‐edge or edge‐to‐face association may occur. The time that it takes to establish a boundary between the gel and the supernatant depends on the size of the clay particles. The smaller the particles, the longer is the settling time. The settling rate depends also on the clay concentration. The boundary between the gel and the clear solution was observed after 1 and 4 d for clay concentrations of 0.1% and 0.05%, respectively, but at higher clay concentrations (0.2 and 0.5%) the suspensions remained stable for more than 7 d.
Effect of Application Method on Availability of Elemental Sulfur in Cropping Sequences
Authors: Chien S. H. , Friesen D. K. , Hamilton B. W. 
Published: July 2010

AbstractThere have been indications that many rice‐growing areas in developing countries are becoming deficient in S. This greenhouse study was conducted to compare the effectiveness of elemental S (ES) mixed with soil (incorporated) or deep‐placed in a band to that of incorporated gypsum on crop growth in sequences of rice‐rice (Oryza sativa L.) or rice‐maize‐maize (Zea mays L.). The soil used was an S‐deficient Josephine sandy loam (Typic Hapoxerults). Rates of S applied were 0, 14, 28, 42, 56 or 112 mg S kg−1. Incorporated elemental S and gypsum were equally effective in increasing grain and straw yields of the first rice crop, whereas deep‐placed ES was less effective. Deep‐placed ES became more effective than incorporated ES and gypsum for the subsequent crop of rice in terms of increasing plant dry‐matter yield. Two statistically distinct relationships were obtained between S uptake by the second rice crop and P‐extractable SO4‐S in the soil prior to that crop: one for incorporated ES and gypsum treatments, and the other for deep‐placed ES treatments. A weak S response was observed for the first maize crop after rice, regardless of sources and methods of S application. However, a strong S response was obtained with the second maize crop (the third crop in the sequence). At lower initial rates of applied S, the residual effect of deep‐placed ES was greater than that of incorporated ES and gypsum. A single relationship for all the S treatments was obtained between total S uptake by the second maize crop and P‐extractable SO4‐S in the soil after the first maize crop.
Revegetation of a Brine‐killed Forest Site
Authors: Auchmoody L. R. , Walters R. S. 
Published: July 2010

AbstractNatural invasion of herbaceous plants and forest tree seedlings on a brine‐killed forest site in northwestern Pennsylvania was evaluated over a 4‐yr period. Brine generated from producing oil wells and accidently discharged to the soil of an Allegheny hardwood stand killed all of the vegetation it contacted, leaving the site unproductive and a visual nuisance. Once the brine source was eliminated, heavy spring rains quickly reduced brine concentrations in the soil to below toxic levels, allowing invasion of vegetation to proceed rapidly. Herbaceous plants and tree seedlings became established in the first year, and by Year 2 the site had regenerated naturally to full stocking with a desirable mix of forest trees. Results show that forest sites damaged by brine from oil wells can heal rapidly without mitigative treatment if the brine source is removed and there is abundant precipitation to flush the soil.
Biological Reduction of Structural Iron in Sodium‐Nontronite
Authors: Wu Jun , Roth Charles B. , Low Philip F. 
Published: July 2010

AbstractTo test the possibility that the structural Fe3+ in clay minerals can be biologically reduced, nontronite was mixed with sucrose and an aqueous extract from a Chinese paddy soil and incubated for 14 d at room temperature. Reflectance spectra, x‐ray diffraction patterns and Fe2+/Fe3+ ratios were determined for the nontronite in the mixture and for the nontronite in its nonreduced and chemically reduced states. It was found that the results for the nontronite in the mixture resembled those for the chemically reduced nontronite but differed markedly from those for the nonreduced nontronite. Therefore, it was concluded that microorganisms from the soil extract were able to reduce the structural Fe3+ in nontronite.
Transformations of Organic Matter Solubilized by Anhydrous Ammonia
Authors: Norman R. J. , Gilmour J. T. , Gale P. M. 
Published: July 2010

AbstractWhile it has been established that liquid anhydrous NH3 (LAA) solubilizes soil organic C, the transformations of the solubilized organic C have not been defined. In order to determine the mechanisms of these transformations, LAA was applied to a Drummer silty clay loam (Typic Haplaquoll) in the laboratory. At 1, 5, 12, 20 and 35 d after LAA application a set of LAA‐treated and nontreated (control) samples were analyzed for soil inorganic N, NH3‐N volatilized, soil pH, water‐soluble organic C (WSOC) and CO2‐C evolved. Biomass C and total hydrolyzed C were estimated. The WSOC concentration increased from 25 mg C kg−1 prior to LAA application to 282 mg C kg−1 on the first day after LAA application. By 35 d after LAA application, the WSOC had decreased to 89 mg C kg−1. Dissimilation, CO2‐C evolved, was an important conversion mechanism for the organic‐C solubilized by the LAA. The LAA‐treated soil had a cumulative CO2‐C production of 630 mg C kg−1 compared to about 200 mg C kg−1 for the control soil over the 35 d after LAA application. Estimations of assimilatory conversion of WSOC to biomass C at microbial efficiencies (E) ranging from 0 to 0.6 indicated that assimilatory conversions could range from 0.25 to 1.5 times the dissimilatory (CO2‐C) conversions, respectively. Total hydrolyzed (CO2 + biomass + WSOC)‐C directly attributable to the LAA at efficiencies of 0 and 0.4 were 445 mg C kg−1 and 701 mg C kg−1, respectively. In a separate experiment it was determined that soil pH had no significant effect on the decrease in WSOC concentration. Consequently, transformations of WSOC were attributed to the microbial processes of assimilation and dissimilation.
Soil Hydrology in Lodgepole Pine Ecosystems in Southeastern Wyoming
Authors: Nyberg Ray C. , Fahey Timothy J. 
Published: July 2010

AbstractThe rates and pathways of water movement through the soil were examined in several lodgepole pine (Pinus contorta ssp. latifolia) forests in southeastern Wyoming to improve our understanding of the dynamics of solute flux in forest ecosystems. We employed internal drainage and tracer pulse methods to determine hydraulic conductivity, and we examined snowmelt infiltration and drainage water chemistry on contrasting soils supporting lodgepole pine forests. Saturated hydraulic conductivity (Ko) values were lognormally distributed for 27 plots at each of two sites examined. The median value was significantly higher at a site on a gravelly, loamy‐sand (median Ko = 1.20 cm/h) than on a bouldery, sandy‐loam (Ko = 0.49). At these sites the high range in both Ko values and in the transit time for a Cl‐ pulse were suggestive of highly variable water flow pathways through the soil. Early in the spring snowmelt period much of the infiltrating water circumvented the soil matrix, probably flowing around entrapped air pockets and through macropores. Although large systematic differences in chemistry were not observed between soil solutions collected with tension and tensionless lysimeters, saturated flow (collected as drips from the ceiling of soil tunnels) contained about three times lower cation concentrations than the lysimeter solutions. To obtain more accurate estimates of nutrient leaching from the tree rooting zone better quantification of the chemistry of percolating soil water is needed.
Consolidation of an Unsaturated Illitic Clay Soil
Authors: Nearing M. A. , West L. T. , Bradford J. M. 
Published: July 2010

AbstractSoil stabilizes with time after disturbance as a function of thixotropy and soil water stress. This study was undertaken to delineate the effects of soil water suction history and thixotropy on soil stabilization and effective stress. Unconfined compressive strength, tensile strength, density, and effective stress as a function of water stress history and time were obtained for a Paulding clay soil (very fine, illitic, non acid, mesic Typic Haplaquepts). Compressive strength was five times greater at 64 kPa suction than at 4 kPa suction, and twice as great at 32 d than at 4 d. Density also increased with suction and time. Compressive strength at 2 kPa suction was 1.8 and 3.2 kPa for prestress suctions of 4 and 32 kPa, respectively; and was 4.4 and 8.9 kPa for prestress suction of 64 kPa after 4 and 32 d, respectively. Prestress and time had no effect on tensile strength apparently because no volume change was allowed. The data supported the hypothesis that strength in unsaturated soil was controlled by soil water stress history. Prestress due to drying induced bonding, which persisted after suction was released if volume change was not restricted. Effective stresses due to soil water suction were greater for strength than for volume change and were influenced by soil structure for the case of strength, but not for the case of volume change.
Prediction and Prevention of Iron‐related Rice Seedling Chlorosis on Everglades Histosols
Authors: Snyder G. H. , Jones D. B. 
Published: July 2010

AbstractRice (Oryza sativa L.) drill‐seeded in certain Histosols in the Everglades Agricultural Area germinates well, but after a few weeks it becomes chlorotic and grows poorly. The condition is termed “rice‐seedling chlorosis.” After flooding, chlorotic seedlings generally assume normal color, except that some seedling mortality occurs, particularly in areas with excessively deep water. Studies were conducted to identify soil and cultivar susceptibility to seedling chlorosis, and then to develop methods for preventing its occurrence. Problem soils were identified on the basis of their total Fe content. Seedling chlorosis occurred in soils containing up to 3.4 g Fe kg−1. Susceptible soils produced a nearly white ash when heated in a muffle furnace for 2 h at 550 °C. Seedling chlorosis was alleviated in all cultivars examined by drilling water‐soluble Fe compounds with the seed at rates of 20 to 30 kg Fe ha−1. The effect of seedling chlorosis on yield varied with cultivar and, to some extent, with experimental conditions. The cv. Leah was very susceptible to chlorosis, and yield was increased by Fe treatment. By contrast, even though visual symptoms were apparent, yield of cv. Labelle evidently was not reduced by seedling chlorosis because Fe treatment did not increase yield. Yield of cv. Lebonnet increased with Fe treatment in two out of three trials. Although the studies did not permit determination of the cause of seedling chlorosis, it appeared that the chlorosis did not result from a simple Fe deficiency.
Effect of Long‐term Tillage Systems and Nitrogen Addition on Potassium Quantity‐Intensity Relationships
Authors: Evangelou V. P. , Blevins R. L. 
Published: July 2010

AbstractThe no‐tillage (NT) management of soils is expected to have an influence on the K+ adsorption characteristics of these soils due to organic matter accumulation. The purpose of this study is to investigate this influence as affected by nitrogen (N) additions. The effect of 16 yr continuous corn (Zea mays L.) production under conventional tillage and no‐tillage management on potassium quantity‐intensity (Q/I) relationships was investigated on soil samples taken at 0–50 mm and 50–150‐mm depths of a Maury silt loam (fine‐silty, mixed, mesic Typic Paleudalfs) from central Kentucky. The results show that the Q/I plot components, labile K+, activity ratio for K+ at equilibrium (ARKo) and linear potential buffering capacity for K+ (PBCK) were affected by tillage and N additions. The no‐tillage soil with and without N fertilizer had the highest quantity of labile K+ at the 0–50 and 50–100‐mm depth. The ARKo was also the highest for the no‐tillage with and without N in comparison to conventional tillage for the two depths. The highest PBCK value was that of conventional tillage no N at the 0–50‐mm depth. The lowest PBCK value was that of no‐tillage no N also at the 0–50‐mm depth. The BaCl2 CEC determination along with the relative affinity for K+ (determined from the slope of plots of ExK/CEC vs. ARK; where ExK = BaCl2 extractable K+) were the best predictors of the relationship PBCK = CEC KGo. The relative affinity for K at the linear portion of the Q/I plots appears to be influenced by organic matter content and pH. Finally, the increase in organic matter content is shown to have a positive influence on the magnitude of high affinity K+ sites.
Soil and Saprolite Characteristics of Vertic and Aquic Hapludults Derived from Triassic Basin Sandstones
Authors: Griffin R. W. , Buol S. W. 
Published: July 2010

AbstractThe chemical, morphological, and mineralogical properties of two soil‐saprolite profiles from the Durham Triassic Basin were determined. The relationship between clay mineralogy and shrink‐swell activity of the soils was also determined. The parent rock from the Vertic Hapludult profile was a fine‐grained red sandstone with muscovite mica, quartz, and feldspars as the dominant primary minerals. The parent rock from the Aquic Hapludult profile was a coarse‐grained gray sandstone with feldspars, muscovite mica, and quartz as the dominant primary minerals. The argillic horizons in both profiles had cracks, slickensides, high clay contents, moderate to high coefficient of linear extensibility (COLE) values, and smectite as the dominant clay mineral. The COLE values are greatest in horizons that display evidence of shrink‐swell activity (cracks and slickensides). The COLE values do not correlate well with either fine or total clay content, which implies that factors other than fine or total clay content influence COLE values. Base saturation percentage increases abruptly below the paralithic contact requiring close examination for correct Ultisol or Alfisol placement.
Soil Aggregate Instability Index and Statistical Determination of Oscillation Time in Water
Authors: Valmis S. , Kerkides P. , Aggelides S. 
Published: July 2010

AbstractA new method for classifying soils on the basis of aggregate stability is presented. The method, based on the concept of an instability index β is simple, quick, and gives reliable results comparable to those obtained with the laborious more commonly used methods. The optimum time of oscillation for the determination of the instability index, β was determined by statistically analyzing data for nine soils. According to this analysis, β is a reliable index of the relative aggregate water‐stability when oscillation times of at least 4 min are used.
Statistical Inferences of Soil Properties and Crop Yields as Spatial Random Functions
Authors: Bresler Eshel , Laufer Asher 
Published: July 2010

AbstractCrop yields are often highly variable due (partly) to spatial heterogeneity of soil properties. The conditional multivariate normal (CMVN) method is systematically described and applied to 24 spatial random functions. These include: 12 soil properties, four soil variables, and two yield components of each of four field crops [wheat (Triticum aestivum L.), vetch (Vicia sativum L.), corn (Zea mays L.), and peanut (Arachis hypogaea L.)]. The statistical parameters characterizing the joint probability density function in a two‐dimensional field were estimated, from 20 to 60 measurements, by the maximum likelihood procedure. An estimation procedure for three parameters of four covariance models (piecewise linear, exponential, spherical, and Gaussian), constant mean, and linear drift, is described. It was found that the covariance function of all the 24 spatial functions can be represented by the four models and that there is a significant two‐dimensional linear drift of the mean. The parameter that represents the nugget effect (i.e. the variance of uncorrelated values of the spatial function) is estimated to be either zero or nonsignificant for the soil properties but has a small significant value for most crop yield components. Soil properties as well as crop yield components are characterized by the existence of a significant correlation scale on the order of 10 to 30 m. Estimations of conditional expectation, conditional covariance, the variance, and the variance of the estimated variance were made and demonstrate that the CMVN method can be applied to real field data. The specific covariance model used generally has a small effect on the estimated results. Comparisons with kriged values and kriging variance demonstrate the similarity and differences in the results.
Evaluation of Nitrogen‐15 Tracer Techniques for Direct Measurement of Denitrification in Soil: II. Simulation Studies
Authors: Vanden Heuvel R. M. , Mulvaney R. L. , Hoeft R. G. 
Published: July 2010

AbstractIn mass spectrometric procedures developed at the University of Illinois for determination of 15N‐labeled dinitrogen (N2) and nitrous oxide (N2O) evolved from soils, the assumption is made that the nitrate (NO−3) undergoing denitrification exists in a single pool that is isotopically uniform. Computer simulation studies were conducted to identify trends associated with errors in measuring denitrification of NO−3 that exists in two or more pools having different enrichments. The results indicate that, for a constant mean 15N enrichment, the magnitude of the error increases as the range of enrichment becomes greater and can increase or decrease with increase in the number of NO−3 pools, depending upon whether there is an increase in the range of enrichment. The error is also affected by the extent to which evolution is distributed among the various pools, but it does not depend upon the overall evolution rate or the 15N enrichment of the fertilizer applied.
Monitoring Saturated Zones in Soils Containing Coarse Fragments
Authors: Burk D. G. , Miles R. J. , Broderson W. D. , Sievers D. M. 
Published: July 2010

AbstractA design for an in situ lateral piezometer constructed of polyvinyl chloride (PVC) components is presented for use in monitoring zones of saturation in soils with appreciable amounts of coarse fragments in dissected hillslope landscapes. This design allows replicated monitoring of water levels in steeply sloping areas which contain up to 60% by volume coarse fragments. Field results from over 150 piezometer units in 36 monitoring sites have shown that matched pairs of piezometers at the sites give consistent results that correlate well with observations in freshly dug profile exposures. This piezometer design is relatively easy to install, inexpensive, and allows correlation of zones of saturation with soil morphological properties.
Constant Rate Rainfall Infiltration in a Bounded Profile: Solutions of a Nonlinear Model
Authors: Broadbridge P. , Knight J. H. , Rogers C. 
Published: July 2010

AbstractWe present new exact solutions to a versatile analytic nonlinear model of single phase vertical unsaturated flow during constant rate rainfall infiltration in a bounded soil profile with an impermeable base. The nonlinear flow equation in a fixed finite region is transformed to a linear diffusion problem with boundary conditions on a shrinking domain. The linear problem is treated by King's method of Laplace‐transform boosts. The analytic solutions illustrate the theoretical differences in the basement moisture build‐up when the water content dependence of the soil hydraulic properties varies from strong to weak. When the rainfall rate exceeds a critical value which is estimated here, surface ponding precedes basement saturation. In this case, time to ponding is approximated well by the expression for the infinite column. When the rainfall rate is less than the critical value (which is greater than the conductivity at saturation), basement saturation precedes surface ponding. In this case, the time to basement saturation is close to the time taken for the rainfall to fill the available pore space.