bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scanning Electron Microscopy of Opaque Opaline Forms Isolated from Forest Soils in Ohio
Authors: Wilding L. P. , Drees L. R. 
Published: July 2010

AbstractOpaque opal bodies isolated from surface horizons (A1) of three Miamian soils were examined with correlative light optical and scanning electron microscope techniques. Opaque bodies comprise from 15 to 70% of the opal isolated from these horizons and range in morphology from spheres to nondescript equidimensional, rod, or elongated forms. Under transmitted light only the gross morphological outline can be deduced. However, with the scanning electron microscope a strong similarity exists between many of the opaque bodies and spheres, cups, mosaic aggregates, and bladed opaline forms isolated from reference deciduous tree leaves. Some of the opaque forms provide positive differentiation of grass vs. forest origin of the opal.
Determining the Acid‐Titratable Basicity of Calcareous Soils
Authors: Miyamoto Seiichi , Bohn Hinrich L. , Renthal James 
Published: July 2010

AbstractThe measured value of acid‐titratable basicity (ATB) or “alkaline earth carbonate from acid neutralization” decreases with increasing soil/solution ratio or the increasing concentration, C, of excess acid. The ATB is almost independent of C, however, in the range of 0.1 to 0.3N acid remaining after neutralization with 0.5N HCl. In coarse‐textured soils, the ATB extrapolated to C = 0 is reasonably close to the soil's carbonate content.
Sulfate Reduction and Sulfide Oxidation in Flooded Soil as Affected by Chemical Oxidants
Authors: Engler R. M. , Patrick W. H. 
Published: July 2010

AbstractThe effect of various chemical oxidants on inhibition of sulfide (S2‐) in a previously reduced soil was studied. Oxygen, KNO3, MnO2, ferricitrophosphate, and FePO4 · 2H2O at rates equivalent to 1,000 ppm O2 (O2 added at rates of either 300 or 500 ppm) were both added prior to flooding and after soil reduction had reached a maximum. The results indicate that the more soluble oxidants had the greatest effects in maintaining more positive redox potentials and in delaying sulfate (SO42‐) reduction to S2‐. The soluble oxidants (KNO3 and ferricitrophosphate) delayed S2‐ production by 17 and 9 days, respectively. The less soluble compounds (MnO2 and FePO4 · 2H2O) were less effective in delaying S2‐ production but persisted longer in preventing maximum S2‐ buildup.Adding the oxidants after maximum S2‐ accumulation showed the most pronounced effect on S2‐ oxidation from KNO3 and the least effect from MnO2. Oxygen at the rate of 500 ppm was also a very effective oxidant. Sulfate reduction to S2‐ and S2‐ oxidation were apparently controlled by, or at best related to the redox potential since SO42‐ reduction and S2‐ oxidation both appeared to commence at potentials in the vicinity of −100 mV.
Detection of Carbonyl Sulfide and Other Gases Emanating from Beef Cattle Manure
Authors: Elliott L. F. , Travis T. A. 
Published: July 2010

AbstractCarbonyl sulfide (COS) was detected in the headspace above anaerobic columns of fresh manure and feedlot compost. One‐tenth ng S/ml of the compound was detected in gases from a debris basin and soil profile of a feedlot also. Carbonyl sulfide has not been reported from these sources previously.During the first 24 hours of anaerobic incubation, COS appeared above the manure. The concentration exceeded 8 ng S/ml the second day and began to decline after 5 days. Hydrogen sulfide followed a similar pattern except that it persisted for 16 days. Only traces of COS were found above some of the replications of the anaerobically incubated compost. Hydrogen sulfide appeared above the compost after 5 days and persisted throughout the 37‐day incubation. Methane appeared more quickly above the manure than above the compost. However, CH4 never exceeded 7.5% above the manure whereas it exceeded 36% above the compost.
Salt Tolerance of Mexican Wheat: I. Effect of NO3 and NaCl on Mineral Nutrition, Growth, and Grain Production of Four Wheats
Authors: B. Carlos Torres , Bingham F. T. 
Published: July 2010

AbstractWheat plants (Triticum aestivum) were grown to full maturity under sand culture conditions with variable levels of substrate NO3 and NaCl. Leaf samples were collected at early spike emergence for chemical analysis of Ca, Mg, Na, K, P, Cl, NO3, and total N. Growth measurements included those of flag leaf length, tiller and spike formation, and total straw and grain.The slower maturing variety, Cajeme 71, grew much more vigorously than the more rapidly maturing varieties Inia 66, Yecora, and Siete Cerros. The salt tolerance of Cajeme 71 was 2‐ to 4‐fold greater than that of the other varieties tested.Leaf NO3 of samples collected at early spike emergence correlated with grain yields irrespective of substrate NaCl levels, suggesting that the growth retardation associated with excessive substrate NaCl was due in part to a Cl‐induced NO3 deficiency.
Radiocarbon Chronology and Problems in Its Interpretation for Quaternary Loess Deposits—South Canterbury, New Zealand
Authors: Runge E. C. A. , Goh K. M. , Rafter T. A. 
Published: July 2010

AbstractThe sequence of events for the loess deposits on the Timaru Downs as indicated by 14C dating of clay‐organic complexes, and whole and fractionated peat deposits is as follows: present soil and surficial peat have been forming from present to 9,900 years BP; uppermost loess was deposited between 9,900 and 11,800 years BP; first palesol and buried peat was formed 11,800 to 31,000 or more years BP; and the second loess was deposited > 31,000 years BP.The mean residence time (MRT) of clay‐organic complexes from the B2 horizon of the modern soil and paleosols was compared to the MRT's of fractionated and unfractionated samples of organic material from stratigraphically related peat deposits. In this study the chronology from whole organic samples was improved by dating fulvic acid, humic acid, and residence (humin) fractions. Humic acid fractions gave consistently older dates than residue fractions. The relative amount of these three fractions provides information about subsequent contamination. Concentrated organic deposits are preferred. However, clay‐organic complexes of paleosols can be used to approximate the chronology of events after a correction for age at time of burial if contamination by organic material through leaching during subsequent soil development can be accounted for. The clay‐organic complex method may extend 14C dating to paleosol horizons enriched with clay (B2 horizons) but devoid of organic enriched horizons (peat, muck, or A horizons).
Performance of Sulfur‐Coated Urea Under Intermittently Flooded Rice Culture in Peru
Authors: Sanchez P. A. , O. A. Gavidia , Ramirez G. E. , Vergara R. , Minguillo F. 
Published: July 2010

AbstractShort‐statured, high yielding rice (Oryza sativa L.) varieties grown extensively in northern Peru require extremely high rates of conventional N sources to achieve maximum yields. The recovery of applied N is extremely low due to the use of intermittent flooding. This water management system results in heavy N losses even with properly timed split applications. In search of simpler and more efficient methods of N management, eight field experiments were conducted in the region to evaluate sulfur‐coated urea (SCU), an experimental, slow‐release N sources supplied by the Tennessee Valley Authority. Rice yields were increased an average of 59% more by pretransplant‐incorporated SCU than by urea or ammonium sulfate applied in the same manner. SCU produced an average of 20% higher grain yield response than topdressed applications of urea or ammonium sulfate. SCU applications increased panicle production, N uptake at harvest, and the apparent recovery of added N. Beneficial effects of SCU were more pronounced in sites where check yields were low, especially less than about 4.8 ton/ha. In sites with high N supplying capacity, SCU produced excessive vegetative growth which resulted in yield reductions at high N rates.Regardless of an assumed 48%‐higher unit N cost in SCU, the overall benefits of pretransplant‐incorporated applications of SCU were favorable since there was a decrease of 40% in the optimum rate of N and the need for precise timing of application was eliminated.
Determination of Equivalent Radii for Rectangular Drains
Authors: Warrick A. W. 
Published: July 2010

AbstractA relationship is developed giving the circular drain size which is equivalent to a rectangular drain. A rectangular drain may result when a highly permeable envelope of rectangular cross‐section is used around a buried drainage tube. A plot of re/ √ ab is given as a function of a/b with re as the circulat drain radius and a and b the semi‐width and semi‐height of the rectangular drain. The minimum value of re/ √ ab is 1.18 and corresponds to a square (which is the case considered by Kirkham and Selim, 1973). The equivalent radius is useful in adapting drainage formulas giving spacings, depth, etc., to rectangular drains.
Calcium‐Magnesium‐Potassium Equilibria in Some California Soils
Authors: Carlson R. M. , Buchanan J. R. 
Published: July 2010

AbstractIon exchange equilibria in several soils were studied to seek equilibrium equations that could be used in chromatographic models dealing with movement and distribution of fertilizer potassium in soil profiles. Soil samples were equilibrated with mixtures of CaCl2, MgCl2, and KCl solutions and then extracted with NH4OAc to determine exchangeable cation compositions at equilibrium. It was necessary to correct the exchangeable cation concentrations by subtracting the cations extracted from nonexchangeable sources by NH4OAc. Vanselow's, Davis', Gapon's, or Kerr's equations would not describe the equilibria. Empirical equations of the form:
urn:x-wiley:03615995:saj2sssaj197303615995003700060019x:equation:saj2sssaj197303615995003700060019x-math-0001 and
urn:x-wiley:03615995:saj2sssaj197303615995003700060019x:equation:saj2sssaj197303615995003700060019x-math-0002 did describe the equilibria with all three cations present, and over a wide range of composition, for all soils studied. In these equations Ai is the solution ion activity, k is the distribution coefficient, Ei is the equivalent fraction of the exchangeable cation, and Di and Pi are arbitrary constants that are characteristic for each soil and each cation.
Ammonia Volatilization from Surface Applications of Ammonium Compounds on Calcareous Soils: I. General Theory
Authors: Fenn L. B. , Kissel D. E. 
Published: July 2010

AbstractVolatilization of NH3 from NH4‐‐N salts applied to the surface of a calcareous soil was investigated. Ammonia losses from surface applied NH4F, (NH4)2SO4, and (NH4)2HPO4 were 68, 54, and 51%, respectively, of the added NH4‐‐N in 100 hours. Ammonium nitrate, NH4Cl, and NH4I lost 18, 18, and 16%, respectively, of the added NH4‐N in 100 hours. An increase in pH at the soil surface resulted in higher loss of NH3. Applications of 550 kg N/ha as NH4F and (NH4)2SO4 increased the pH from 7.6 to 8.9 and 8.1, although pH decreased rapidly with time. Soil pH decreased to 6.8 by the addition of 550 kg NH4‐N/ha as NH4NO3 and changed very little in 50 hours.Ammonium sulfate applied to soils saturated with Mg2+ and Ba2+ gave similar results. Solubility of the apparent reaction product was the major factor regulating NH3 volatilization. Formation of a Ca2+ reaction product, such as CaSO4, tends to drive the reaction to the right and favors formation of (NH4)2CO3. A proposed mechanism of the observed loss of NH3 is as follows: when an ammonium salt dissolves in a calcareous soil, (NH4)2CO3 and a Ca2+ salt of varying solubility forms. Ammonium carbonate subsequently decomposes, losing CO2 at a faster rate than NH3. This causes formation of NH4OH and an increase in pH and greater NH3 losses.
Chemical and Spectroscopic Methods for Assessing Subsidence in Florida Histosols
Authors: Volk B. G. , Schnitzer M. 
Published: July 2010

AbstractThe extent of subsidence of cultivated histosols in the Everglades of southern Florida can be assessed by chemical and spectroscopic methods. Higher subsidence rates tend to be associated with the following changes in the chemistry of humic acids, the principal constituent of histosols: (i) increases in CO2H, phenolic OH, quinone, and ketonic C=O groups; (ii) decreases in aliphatic structures as shown by IR spectra and alcoholic OH groups; and (iii) decreases in molecular complexity as indicated by E4/E6 ratios and possibly by free radical measurements.The chemical reactions involved appear to be mainly oxidative, leading at first to the degradation of aliphatic structures to C=O and CO2H groups, and finally to attacking the more stable aromatic structures with degradation to CO2 and H2O.Functional group analysis and measurements of E4/E6 ratios are useful and experimentally simple methods for estimating the degree of degradation of Florida histosols.
Effects of Chelated and Nonchelated Cobalt and Copper on Yields and Microelement Composition of Bush Beans Grown on Calcareous Soil in a Glasshouse
Authors: Wallace A. , Mueller R. T. 
Published: July 2010

AbstractSeveral levels of chelated [EDTA (ethylene diaminetetraacetate)] and nonchelated Co and Cu were applied to bush beans (Phaseolus vulgaris L. var. ‘Improved Tendergreen’) grown in a glasshouse in calcareous Hacienda loam soil. Objectives of the study were to determine if chelated Co and Cu were more available in the calcareous soil than were inorganic sources, and if chelating agents contribute to toxicities at relatively high levels of Co and Cu. CoEDTA and CuEDTA applications caused higher levels of Co and Cu, respectively, in the plants than did inorganic sulfate sources. The applications of both metal chelates caused slight depressions in yields of dry matter at 50 ppm metal added and CoEDTA behaved similarly at 25 ppm Co. Each metal chelate was associated with a decreased Fe concentration in leaves at the highest application level. The Co in leaves was similar for applications of 50 ppm Co as CoSO4 and 2.5 ppm Co as CoEDTA. The Cu concentration in leaves was greater for an application of 5 ppm Cu as CuEDTA than for 25 or 50 ppm Cu as CuSO4.
Water‐Sediment Splitter for Runoff Samples Containing Coarse‐Grained Sediment
Authors: Fleming Walter G. , Leonard Ralph A. 
Published: July 2010

AbstractA water‐sediment sample splitter was designed and constructed for dividing samples up to 20 liters into three equal and representative smaller samples for chemical and physical analyses. This funnel‐shaped device with a mechanical agitator divides samples containing particles up to 2 mm without first separating the sediment from the water. Evaluation showed that the splitter divided samples containing coarse sediments into three parts with a distribution of 33% ± 2% in each. The device has application in assuring representative samples of runoff from watershed or similar runoff studies.
Flux‐Gradient Relationships and Soil‐Water Diffusivity from Curves of Water Content versus Time
Authors: Nofziger D. L. , Ahuja L. R. , Swartzendruber D. 
Published: July 2010

AbstractDirect analysis of a family of curves of soil‐water content versus time at different fixed positions enables assessment of the flux‐gradient relationship prior to the calculation of soilwater diffusivity. The method is evaluated on both smooth and random‐error data generated from the solution of the horizontal soil‐water intake problem with a known diffusivity function. Interpolation, differentiation, and integration are carried out by least‐squares curve fitting based on the two recently developed techniques of parabolic splines and sliding parabolas, with all computations performed by computer. Results are excellent for both smooth and random‐error input data, whether in terms of recovering the original known diffusivity function, assessing the nature of the flux‐gradient relationship, or in making the numerous checks and validations at various intermediate stages of computation. The method applies for any horizontal soil‐wetting process independently of the specific boundary conditions, including water entry through a nonzero inlet resistance. It should be adaptable to horizontal dewatering, and extendable to vertical flow.
Properties of Some Soils of the Upper Amazon Basin of Peru
Authors: Sanchez P. A. , Buol S. W. 
Published: July 2010

AbstractSeveral representative soil profiles of the Peruvian Amazon jungle were collected in the vicinity of Yurimaguas and Iquitos and characterized in the laboratory in order to classify them according to the US soil taxonomic system. The most extensive well‐drained soils are Typic Paleudults; the poorly‐drained ones are Typic Tropaqualfs or Tropaquepts. The Paleudults were predominantly of kaolinitic mineralogy with small quantities of 2:1 minerals present. The poorly‐drained soils were predominantly montmorillonitic or of mixed mineralogy. Where coarsetextured parent materials occur in localized areas. Tropaquods and Haplorthods are found. High base status Haplaquolls are found along the margins of the Amazon and Napo Rivers. The base status of the Paleudults is not as low as in the main soils of the South American savannas. The base status of the more poorly‐drained soils is higher. Evidence from surrounding countries suggests that these soils are very extensive in the Upper Amazon Basin of South America, outside the influence of the Brazilian and Guyana shields. These areas have been previously mapped as Oxisols or their equivalents.
Straw Buildup in Soil with Stubble Mulch Fallow in the Semiarid Great Plains
Authors: Greb B. W. , Black A. L. , Smika D. E. 
Published: July 2010

AbstractThe quantity of wheat (Triticum aestivum L.) straw in the 0 to 7.6 cm depth of soil in wheat‐fallow rotations was determined at Sidney, Montana, Akron, Colorado, North Platte, Nebraska, and Bushland, Texas. Rotation treatments varied between locations but included straw rates, dates of primary tillage, and straw burial times. Types of primary tillage were also studied with continuous wheat at Bushland, Texas.Quantities of straw found mixed in the surface 7.6 cm of soil at the four Great Plains locations ranged from 1,300 to 7,480 kg/ha. The straw quantities found are influenced by duration of wheat‐fallow rotation, date, and type of primary tillage and straw burial time but were not proportional to the rates of straw mulch used at the beginning of fallow. In a long‐term study plots at Bushland, Texas, straw build‐up was significantly greater with continuous wheat than with wheatfallow. Adding nitrogen fertilizer even at high rates did not influence the amount of straw found in soil at Sidney, Montana or North Platte, Nebraska.
Land Response Units — An Aid to Forest Land Management
Authors: Leven A. A. , Meurisse R. T. , Carleton J. O. , Williams J. A. 
Published: July 2010

AbstractLand Response Units offer a means of grouping broad areas of land that have similar capabilities to produce biomass, and have similar sensitivities to man's uses. The capability of the land to produce flora and fauna is estimated by evaluating the soil ecofactors that sustain the environment, i.e., moisture, temperature, and nutrients. Moisture and temperature factors can be evaluated by classifying the soils using the Soil Taxonomy of the National Cooperative Soil Survey. Soil moisture regimes indicate plant available moisture, and soil temperature regimes indicate temperature conditions for plant growth. Nutrient regimes can be estimated by evaluating soil depth, color, texture, and pH. Sensitivity to man's uses is estimated by evaluating the erosion hazard, runoff potential, and slope gradient of the land. These three factors are used to estimate the ability of the land to accept man's activities without serious loss of productivity or stability.The Land Response Unit concept is adaptable for use on intensively managed agricultural lands as well as less intensively managed lands.
Anion Exclusion and Coupling Effects in Nonsteady Transport Through Unsaturated Soils: II. Laboratory and Numerical Experiments
Authors: Bresler E. , Laufer A. 
Published: July 2010

AbstractA numerical model for the simultaneous transport of anions and water as developed in Part I of this work was compared with measured chloride and water flow data. Laboratory soil‐column experiments were conducted under conditions of infiltration, redistribution, and evaporation of water in the upper part of the soil profile. The effects of convection, ionic diffusion, mechanical dispersion, anion exclusion, and water flow in response to salt concentration gradients on the comparison between numerical and measured data were considered jointly. The agreement between theory and experiment, as expressed by flow into and out of the soil column and by water content and salt distribution profiles, was generally good. The results were relatively insensitive to anion exclusion and osmotic effects. Estimates of dispersivity as obtained from miscible displacement experiments were found to be sufficient for prediction purposes. The numerical as well as the laboratory data indicate that for the conditions studied, osmotic gradients and anion exclusion effects are of minor importance.
Packing‐Induced Radial Particle‐Size Segregation: Influence on Hydrodynamic Dispersion and Water Transfer Measurements
Authors: Ripple C. D. , James R. V. , Rubin Jacob 
Published: July 2010

AbstractPrevious laboratory studies have shown that radial particlesize segregation occurs when soil columns are prepared with the aid of vibratory compaction. This segregation is characterized by a greater proportion of coarser particles near the periphery than in the central region of the column. A specially devised, alternative repacking technique, utilizing a vibration‐free impacting apparatus, reduced such segregation in soil columns to an acceptably low level. Soil columns prepared by the above two packing procedures (i.e., with or without induced radial segregation) exhibited significant differences in their water flow and salt transport properties. Miscible displacement tests exhibited effluent‐concentration histories that agree with currently accepted one‐dimensional dispersion theory in the case of nonsegregated soil columns. On the other hand the results from segregated soil columns could not be reconciled with this theory. Horizontal infiltration into either segregated or nonsegregated soil columns produced significantly different moisture content profiles. However, it yielded rather similar relations between infiltration volume and the square root of time.