bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of Force vs. Time Relations for Waterdrop Impact
Authors: Nearing M. A. , Bradford J. M. , Holtz R. D. 
Published: July 2010

AbstractForce vs. time relationships of waterdrop impact are important for understanding the process of erosion caused by soil splash. Waterdrop impact forces were measured for 3.31‐, 3.83‐, 4.51‐, and 5.25‐mm diam drops falling from a height of 14.0 m onto piezoelectric transducers with rise times of 2 and 5 µs. Peak forces occurred within 13 to 21 µs of initial contact, ranged from 1.0 to 3.8 N, and decreased to 0.5 N after approximately 100 µs. Average pressures under impact were calculated from the force measurements and an approximateion of waterdrop contact area as a function of time and decreased to 100 kPa after 50 µs. The results indicated that the times and magnitudes of the force of impact were poorly predicted from currently used models and that the compressional wave generated in the water upon impact is probably an important parameter in determining the level and time distribution of forces during impact.
The Influence of Pretreatment Forest Soil Variability on Interpretation of Posttreatment Results
Authors: Slay J. Melinda , Lockaby B. G. , Adams J. C. , Vidrine C. G. 
Published: July 2010

AbstractAnalysis of covariance procedures were used to evaluate differences in forest soil chemical properties among four site preparation techniques. Comparisons were made between analyses of variance adjusted with pretreatment soil chemical data used as covariates and unadjusted analysis of variance results. These comparisons indicated that failure to adjust for pretreatment spatial variation in soil chemical properties would lead to misinterpretation of the study results. This misinterpretation involved different rankings (for unadjusted vs. adjusted) of the site preparation treatment effects on soil N, P, K, Ca, and Mg concentrations.
X‐ray Photoelectron Studies of Anion Adsorption on Goethite
Authors: Martin Ronald R. , Smart Roger St. C. 
Published: July 2010

AbstractX‐ray photoelectron spectroscopy (XPS) was evaluated as a technique to study anion adsorption on soil minerals; in this case, the well‐characterized systems of phosphate, sulfate, and selenite adsorption on goethite (α‐FeOOH). X‐ray photoelectron spectroscopy measured directly the surface coverage, the form of the adsorbed species and substrate, and the pH dependence of adsorption. The results confirm the previously reported adsorption mode in which two A‐type hydroxyls are replaced by coordination of two of the oxygen atoms of the anion.
A Sensitive Colorimetric Method for the Quantitation of Selenite in Soil Solutions and Natural Waters
Authors: Holtzclaw Kenneth M. , Neal Rosemary H. , Sposito Garrison , Traina Samuel J. 
Published: July 2010

AbstractA sensitive colorimetric method for the quantitation of selenite in aqueous solution at concentrations between 0.15 and 30 µmol kg−1 was developed. The method is based on the formation of a colored complex between selenite and 2,3‐diaminonapthalene (DAN) and is selective for selenite in selenite‐selenate mixtures. The yellow color of the complex is stable for at least 48 h and there appear to be no interference effects from selenate, sulfate, and other normal soil solution ionic constituents at moderate to high concentrations. Because the method is specific for selenite, it can be combined with acid digestion and hydrolysis to quantitate total Se and to speciate Se in soil solutions containing both selenite and selenate.
Nonexchangeable Ammonium Nitrogen Contribution to Plant Available Nitrogen
Authors: Baethgen Walter E. , Alley M. M. 
Published: July 2010

AbstractRecent European research has shown that nonexchangeable NH+4‐N may be released from soil and utilized by crops. Surface and subsoil samples were collected from agriculturally important soils of Coastal Plain, Piedmont, and Ridge and Valley regions of Virginia to determine the relative importance of different soil N fractions for supplying N to wheat (Triticum aestivum L. em Thell) grown in the greenhouse. Exchangeable and nonexchangeable NH+4‐N, NO‐3‐N, total N, organic matter contents and an index of organic N availability were measured on all samples. Plant available N was measured by N uptake of successive wheat crops grown in the greenhouse. Multiple linear regression models for different groups of samples were used to determine the significance of the different soil N fractions to the plant available N supply, and to predict N uptake by wheat. Best models were selected considering fit, significance of the regression coefficients, and predictive ability. Collinearity effects on the models were reduced by using Principal Components regression. All the soils provided significant amounts of N to the wheat in both the first and second crops. Exchangeable NH+4‐N and NO‐3‐N were the major initial sources of plant available N. Nonexchangeable NH+4‐N contents were highest in fine‐textured soils, and/or soils with large amounts of previously‐added N fertilizers. This soil N fraction was a significant contributor to the plant available N supply for all soil groups, and amounts up to 129 mg kg−1 soil were measured. Interaction of nonexchangeable NH+4‐N with readily‐available N was found in all soil groups. Nonexchangeable NH+4‐N should be considered as a potential plant available N source in future research.
Greenhouse Evaluation of Elemental Sulfur and Gypsum for Flooded Rice
Authors: Chien S. H. , Hellums D. T. , Henao J. 
Published: July 2010

AbstractRecently, S deficiency has become a problem in many flooded soils for rice (Oryza sativa L.) production because of the increased use of high‐analysis of N and P fertilizers that do not contain S. The objective of this study was to compare the relative agronomic effectiveness (RAE) of powdered elemental S and urea‐S melt (prilled or powdered) to that of gypsum in a pot trial using an S‐deficient Josephine soil (fine‐loamy, mixed mesic, Typic Haplozerults). The RAE value of powdered elemental S for grain yield was 78% with respect to gypsum when both fertilizers were surface broadcast onto the soil surface at rates up to 40 mg S kg−1. Prilled urea‐S melt was found to be significantly less effective than powdered urea‐S melt in terms of increasing rice grain yield at a rate of 20 mg kg−1. Placement of urea had no effect on rice response to elemental S for a given S placement method. The various S placement methods demonstrated the following order of agronomic effectiveness of elemental S: surface broadcast = incorporation > deep placement. Rice response to gypsum, on the other hand, was found to be the same, irrespective of placement method. Prilled urea‐S melt was approximately 61% as effective as gypsum in increasing rice grain yield when incorporated into the soil at 20 mg S kg−1.
Chemical Properties of the Rhizosphere in an Acid Subsoil
Authors: Kirlew Peter W. , Bouldin David R. 
Published: July 2010

AbstractA method of corn seedling culture was developed which allowed growth of the root systems in samples of an acid subsoil (pH 4.7‐5.0) for at least 2 weeks after seedling emergence, without adding additional water to the subsoil. This method was used to culture corn inbred and corn hybrid seedlings in samples of acid subsoil in two separate greenhouse studies. Bulk (non‐rhizosphere) soil and rhizosphere soil samples obtained in these studies were assayed for pH, KCl‐extractable Ca, KCl‐extractable Al, and water‐extractable Ca. The pH of rhizosphere samples was less than that of the bulk samples for all inbreds and hybrids. This pH decrease was 0.16 in one experiment with inbreds, and 0.11 in another experiment with hybrids. In comparison to the bulk soil, the rhizosphere soil contained 0.16 cmolc kg−1 more KCl‐extractable Al, 0.13 cmolc kg−1 less KCl‐extractable Ca, 0.023 cmolc kg−1 more water‐extractable Ca, and 0.10 cmolc kg−1 less total Ca. The difference in the sum of KCl‐extractable Al plus Ca between bulk and rhizosphere soils was not statistically significant. The results of both studies are consistent with the hypothesis that Ca uptake by the root depleted the Ca in the rhizosphere, that H ions were released by the root in response to excess cation (vs. anion) uptake and that this excess H+ dissolved basic Al compounds, which increased the KCl‐extractable Al. The lack of statistically significant differences between rhizosphere and bulk soil parameters among hybrids/inbreds indicate that differential pH changes in the rhizosphere are not the chief mechanism of any differential Al tolerance among these corn inbreds and hybrids.
Effect of Parent Rocks on Chemical and Mineralogical Properties of Some Oxisols in Brazil
Authors: Curi N. , Franzmeier D. P. 
Published: July 2010

AbstractA toposequence of soils developed primarily from basalt in the Central Plateau of Brazil and a pedon developed primarily from itabirite (a hematite‐quartz metamorphic rock) were studied in the Quadrilatero Ferrifero. The itabirite‐derived Oxisol consists almost entirely—900 to 950 g kg−1 (90‐95%)—of Fe oxides and oxyhydroxides, compared with 250 to 300 g kg−1 in the basalt‐derived Oxisol. The soil on itabirite also has coarser particle size, higher particle density, and somewhat lower surface area. It lacks kaolinite and gibbsite but contains more goethite and has greater magnetic susceptibility. It also is much lower in all essential plant nutrients (except Fe and P), and much lower in several non‐nutrient minor elements as well. Magnetite grains in basalt are relatively abundant in minor elements which could be released slowly during mineral weathering. The effect of the parent material is still evident even in highly weathered soils, indicating the need for the separation between itabirite‐ and basalt‐derived Oxisols in a system of soil classification. In itabirite‐derived soils the Fe2O3/TiO2 ratio (H2SO4 digestion) is >16 and the magnetic susceptibility of the whole soil is > 189 × 10−6 m3 kg−1 (15 000 × 10−6 cgs). These limits of soil properties reflect the original parent material and could be the differentiating characteristics in soil classification systems. Particle density, amount of trace elements, and capacity to fix phosphorus are accessory properties associated with the differentiating characteristics.
Soil Property Comparisons in Virgin Grasslands Between Grazed and Nongrazed Management Systems
Authors: Bauer Armand , Cole C.V. , Black A.L. 
Published: July 2010

AbstractSoil organic C and total N contents of grazed virgin grasslands have been used as the comparison standard to assess the change in soil organic matter (OM) generated by cultivation in the Northern Great Plains. The assumption has been that grassland soil properties were not altered by livestock grazing and therefore reflect the native grassland condition at the time man began cultivating for crop production. In this study, soil properties of grazed and nongrazed (relict) virgin grasslands are compared to assess the effect of grazing. Four sites each of moderately coarse‐, medium‐, and fine‐textured soils under grazed and under relict management were sampled at 0‐ to 0.076‐, 0.076‐ to 0.152‐, 0.152‐ to 0.305‐, and 0.305‐ to 0.457‐m depths. Analyses were made to compare organic C, total N, total P, organic P, and inorganic P contents, and bulk density between the management systems. Nutrient contents differed between the two management systems.The largest content was not exclusively associated with either system; neither was the difference the same among textural groups or sampling depth. When averaged over all soil textures and depths, organic C and total P contents showed opposite trends from total N. Organic C and total P contents to 0.457 m were larger in relict grasslands by about 1.27 and 0.029 kg m−2, respectively, while the total N content was larger in grazed grasslands by about 0.163 kg m−2. Since the fencing of grasslands for livestock control about 75‐yr ago, differences between the two systems have developed at an average annual rate of about 165 kg C, 20 kg N, and 4 kg P ha−1. Bulk densities were highest in grazed grassland in the uppermost 0.076 m. Based upon the organic C and total N contents in relict grasslands, reported losses of OM resulting from cultivation have been either over‐ or under‐estimated, depending on whether organic C or total N content in grazed grasslands has been used as the comparison standard.
Dependence of “True” Surface Energy of Soils on Air Entry Pore Size and Chemical Constituents
Authors: Hadas A. 
Published: July 2010

AbstractStability and strength of soil structure depend on soil constituents and the manner in which they interact with each other. Some constituents, such as CaCO3, organic matter (OM), and Fe oxide act as cementing agents. Soil structure strength dependence on those soil constituents was studied. Apparent and “true” surface energy of a soil was defined as the amount of energy required to produce a new unit of surface area or propagate a crack, respectively. These energy values were determined by modifying Sack's (1946) and Griffith's (1924) theory to data obtained from brittle fracture tests on molded soil samples from 16 soils varying in clay, OM, CaCO3, and Fe2O3 contents. A negative linear relationship between the apparent surface energy and the pore radius at air entry was found. No distinct relationship was found between the “true” surface energy of the soils and the contents of CaCO3 and Fe oxide. An inverse relationship was found between “true” surface energy and cation exchange capacity. Possible new research directions are discussed in view of the data presented.
Root Density, Abundance, and Distribution in the Mixed Mesophytic Forest of Eastern Kentucky
Authors: Kalisz P. J. , Zimmerman R. W. , Muller R. N. 
Published: July 2010

AbstractRoot density, abundance, and distribution to bedrock or to the 150‐cm depth were measured in 40 soil profiles spanning a species compositional gradient. Profile morphology was relatively uniform for the soils examined. Root density (LV; length per unit soil volume) was not related to bulk density or coarse fragment percentage within individual sampling depths, and decreased exponentially from ranges of 18200 to 35900 m m−3 in the 0‐ to 5‐cm depth, to 400 to 700 m m−3 in the 100‐ to 150‐cm depth. LV in the upper 100 cm of soil was highest under oak‐dominated forests on the xeric sites, averaging ∼ 60% greater than transitional or beech stands. Root abundance (LA; length per unit ground surface area) was not related to profile depth, and increased along the gradient from mesic to xeric forests. Total profile LA averaged 5800, 6400, and 10000 m m−2, respectively, under beech (Fagus grandifolia), transitional (primarily, Carya spp., Quercus rubra, and Liriodendron tulipifera), and oak (Quercus spp.) forests. LA in both Oe and mineral soil horizons increased in the order beech < transitional < oak. On the average, 17% of the root length occurred in the Oe horizon, 26% in the A horizon, and 90% within the solum to a depth of ∼ 65 cm. Variations in LV and LA across the species compositional gradient are most simply interpreted as species adaptations to sites with differing moisture regimes.
Significance of Sulfide Oxidation in Soil Salinization in Southeastern Saskatchewan, Canada
Authors: Mermut A. R. , Arshad M. A. 
Published: July 2010

AbstractSeveral deep soil columns in the Weyburn area, Saskatchewan, Canada, show features related to S2‐ oxidation, including the presence of high amounts of SO2‐4 salts and low pH. A soil 4‐km west of Cedoux that had 1‐m layer of till underlain by Cretaceous marine shale was selected to characterize these features. X‐ray diffraction, scanning electron microscope, and chemical techniques confirmed the presence of well‐developed crystals of natrojarosite between the 100‐ to 600‐cm depth, and sulfides below 550 cm. Sulfate was the predominant water‐soluble anion, with Na+ followed by Mg2+ and Ca2+ as major cations. Accumulation of sulfate in the Cedoux soil and similar soils in the area was attributed to sulfide oxidation and hydrolysis of natrojarosite. Sulfate salts probably are still produced at present. Due to their mobility and recycling in the soils and Cretaceous marine shale it was difficult to bring to light the genesis of salts in Saskatchewan.
Use of Soil‐profile Sulfate Data for Predicting Crop Response to Sulfur
Authors: Hue N. V. , Cope J. T. 
Published: July 2010

AbstractSulfur deficiencies in early growth stages do not always result in final yield reduction in many crops. This suggests a greater contribution of subsoil sulfate (SO4) and/or of S mineralization later in the season to the S requirements of plants. The subsoil SO4 contribution should be assessed in order to develop a method that can reliably predict crop response to S. A greenhouse experiment was conducted with various combinations of topsoil (0‐20 cm layer) and subsoil (20‐60 cm layer) materials from a Hartsells series (Typic Hapludult) where crop response to S had been observed, and a Benndale series (Typic Paleudult) where there was no response to S in field experiments. By determining soil SO4 depletion in each layer by crops of grain sorghum (Sorghum bicolor L. Moench.), it was extimated that plants derived approximately 0.55 of their S need from the surface 0 to 20 cm, and the remaining 0.45 from the subsoil. Subsequently, a weighted concentration of soil SO4 for the entire profile was calculated; and values of 13.8 mg S kg−1 for extractable SO4 and 0.25 mM for soil‐solution SO4 were the minimum concentrations above which no crop response to S is expected. The use of weighted means of soil‐profile SO4 data correctly predicted yield responses to S of soybeans (Glycine max L. Merr.), corn (Zea Mays L.), and sorghum in a field experiment, which were previously unexplained based on SO4 concentrations of the surface soil.
The Effect of Calcium and Magnesium on Soil Nitrate Determination by Automated Segmented‐flow Methods
Authors: Ananth S. , Moraghan J. T. 
Published: July 2010

AbstractAn automated procedure, involving the reduction of NO‐3 to NO‐2 by an alkaline solution of hydrazine sulfate containing traces of Cu2+, is commonly used for determination of small quantities of NO‐3‐N in electro‐ultrafiltration (EUF) extracts of soils. When this reduction method was employed to determine NO‐3‐N in aqueous extracts from certain Calciaquolls, low and erratic results were obtained with 24 of 46 soil samples. The problem extracts contained high levels of Ca2+ and Mg2+ that interfered with the method. Soil extracts with <40 mg Ca2+ L−1 and 15 mg Mg2+ L−1 presented no analytical problems. Placement of a cation exchange resin column between the sampler and pump of a Technicon AutoAnalyzer II overcame the interference, due presumably to removal of Ca2+ and Mg2+ from the flow line. Solution studies revealed that Ca2+ and especially Mg2+ prevented quantitative reduction of NO‐3 to NO‐2. No analytical problems were encountered with any of the soil extracts when a Cd‐Cu column was used to reduce NO‐3 to NO‐2. Any hydrazine sulfate reduction method should be carefully evaluated when newly introduced as an analytical procedure for soil NO‐3‐N determination.
The Stable Isotope Chemistry of a Native and Irrigated Typic Natrargid in the San Joaquin Valley of California
Authors: Amundson Ronald G. , Lund L. J. 
Published: July 2010

AbstractThe stable C and O isotope chemistry of native and irrigated Typic Natrargids was examined in order to determine the relationship between the climate and vegetation and the δ13C and δ18O of the native pedogenic carbonates (CaCO3) and the effect of irrigation on the CaCO3 in the cultivated soils. The native soil had a sparse vegetative cover consisting of grasses and salt tolerant shrubs, especially Atriplex polycarpa (Torr.), S. Wats. The δ13C of the CaCO3 reflected the mixture of C3 and C4 vegetation and the δ18O of the CaCO3 suggested that it had formed from soil H2O that had undergone extensive amounts of evaporation. At the time of sampling, alfalfa (Medicago sativa L.) was being grown on the irrigated soils. These soils had CO2 partial pressures of up to 7 KPa, nearly 20 times that of the native soil. The δ13C of the CaCO3 in the irrigated soils was not significantly different than that of the native soils which was due, in part, to the relatively small isotopic difference between the newly formed CaCO3 in the irrigated soil and much of that which occurred naturally. However, the δ18O of CaCO3 in the irrigated soils appeared to be shifted to more negative values than the δ18O of the native CaCO3. Based on the differences in the δ18O of the CaCO3 in the irrigated and native soils, it was semiquantitatively estimated that between 10 to 40% of the carbonate in the irrigated soils was newly formed or had dissolved and reprecipitated as a result of irrigation, increased biological activity, and the application of chemical amendments.
Cumulative Effects of Simulated Acid Rain on Soil Chemical and Microbial Characteristics and Conifer Seedling Growth
Authors: McColl J. G. , Firestone M. K. 
Published: July 2010

AbstractEffects of simulated acid rain treatments of HNO3 and H2SO4, in the mole ratio of 3:1 and pH 5.6, 4.5, 4.0, and 3.0, were tested on seedlings of Douglas‐fir (Pseudotsuga menzesii [Mirb.] Franco), sugar pine (Pinus lambertiana Dougl.), and ponderosa pine (Pinus ponderosa Laws) growing in A‐horizon samples of two forest soils. Two wet periods of 34 and 27 weeks duration, separated by a dry period of 18 weeks, simulated climatic conditions common in the Sierra Nevada, California. Representative results are presented for soil supporting Douglas‐fir, plus results of growth and shoot‐N for all three species. Effects differed between soils but were usually increased from one wet period to the next, and markedly decreased with soil depth. Effects commonly appeared in the pH 3.0 treatment only. Little or no effects were noted for seedling growth, visual symptoms of foliar damage, N concentration in shoots, or for the general soil microbial assays of CO2 evolution and microbial biomass. There were notable decreases in exchangeable cations and soil pH, and increases in soil Al, Mn, Fe, and Zn. Effects on N transformations in soil were inconsistent, but in the pH 3.0 treatment there were some significant increases in mineralizable N and denitrification potential, and decreases in nitrification potential. Similar results were obtained for N transformations in one of the same forest soils supporting ponderosa pine in an earlier experiment of only 12 weeks duration, but at greater acidity of pH 2.0.
Occurrence of High‐charge Beidellite in a Vertic Haplaquoll of Northwestern Minnesota
Authors: Badraoui M. , Bloom P. R. , Rust R. H. 
Published: July 2010

AbstractThe 2:1 layer silicate mineralogy of a Vertic Haplaquoll of north‐western Minnesota was studied using x‐ray diffraction and determination of cation exchange capacity (CEC). The x‐ray diffraction behavior of Li‐ and K‐saturated samples demonstrated that a highcharge smectite with tetrahedral charge dominates the mineralogy of both the coarse and the fine clay fractions. The high CEC and the large difference between Li‐CEC and K‐CEC confirmed the x‐ray results. Alkylammonium‐clay complex basal spacings show two phases of 2:1 clays; a high charge (about 0.9 molc per ½ unit cell formula) phase concentrated in the coarse clay and an Fe‐rich beidellite with a charge of 0.4 to 0.5 molc per ½ unit cell formula. The high charge phase largely represents K+ ‐depleted mica formed during the analytical procedure. This phase may also contain some soil vermiculite. The results presented in this study suggest that beidellite is a product of mica weathering, and that during weathering soil mica is transformed first to a vermiculite then to a beidellite, preserving the tetrahedral character of the charge.