bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grain Fragmentation in Preparing Samples for Particle‐Size Analysis
Authors: Walker P. H. , Hutka J. 
Published: July 2010

AbstractSome naturally occurring granular materials, such as granitic quartz and sand‐sized fragments of sedimentary rocks, are susceptible to breakage and may cause problems when present in soil samples being prepared for particle‐size analysis. An assessment was made of three methods of the kind used for disaggregating soils, with prepared samples of granitic alluvium and alluvium rich in argillaceous and quartzitic sedimentary rock fragments. An ultrasonic probe caused least fragmentation of the samples tested; an end‐over‐end shaker caused slight fragmentation of coarse fractions; a drink mixer operated for 15 min caused considerable fragmentation of medium and coarse‐sized fractions.
Soil Conditions Under Old Field and Forest Cover in Southern Illinois
Authors: Rolfe Gary L. , Boggess W. R. 
Published: July 2010

AbstractA comparison of soil conditions under pine plantations and old fields of the same age was made for three loess‐derived soil types in southern Illinois. Native hardwood stands were used for comparing soil changes under the pine and old‐field seral stages. Characteristics studied included bulk density; hydraulic conductivity; organic content; pH; and exchangeable Ca, Mg, Na, K, and H. Under native hardwoods organic matter, pH, and exchangeable bases were higher, while bulk density was lower than under pine or old‐field cover. Under pine cover bulk density, hydraulic conductivity, and exchangeable base levels were improved over old‐field conditions, but organic matter was higher under the old‐field vegetation. No significant differences were noted in pH. The introduced pine seral stage has considerably ameliorated soil conditions since abandonment from agriculture, and there appears to be a trend toward conditions typical of native hardwood stands.
A Note on A Three‐Parameter Soil‐Water Diffusivity Function‐Application to the Horizontal Infiltration of Water
Authors: Parlange Jean‐Yves 
Published: July 2010

AbstractA realistic water‐diffusivity function depending on three parameters was described recently by Ahuja and Swartzendruber (1972). An analytical solution for the horizontal infiltration of water and for such a diffusivity function is presented here. The result is expressed in terms of elementary functions and agrees very well with experimental observations.
Limitations of Darcy's Law in Glass Bead Porous Media
Authors: Boersma L. , Lindstrom F. T. , Saxena S. K. 
Published: July 2010

AbstractIn a series of dispersion experiments in porous systems made up of glass beads, it was found that for flow of water through small pores at low gradients, flow rates are not proportional to the hydraulic gradient but are proportional to this gradient raised to the power 1/n, where n > 1. These results agree with literature reports which have indicated that for flow through small pores, the flow fields undergo a change from Newtonian to non‐Newtonian behavior. The deviations have been attributed to force fields associated with the clay minerals, changes in the clay fabric making up the porous system, and electro‐viscous effects. In these experiments, the porous systems were made up of glass beads so that all effects attributed to clay‐water interactions could be ruled out. The functional relationship between the factor 1/n and pore radius r was found to be approximated by 1/n = 1 − exp(−1.32r0.31).
Cultural Practices for Irrigated Winter Wheat Production
Authors: Unger Paul W. , Allen Ronald R. , Parker Jessie J. 
Published: July 2010

AbstractRototilling, moldboard plowing, disking, burn‐listing, and listing were satisfactory tillage methods for managing the residues produced by continuous irrigated winter wheat (Triticum aestivum L.). Grain yields averaged highest for moldboard plowing and lowest for lister plowing. Nitrogen fertilizer at 90 or 135 kg N/ha resulted in significant grain and residue yield differences in a few years, but no consistent trends were apparent. Irrigation water infiltration was highest for moldboard plowing and lowest for lister plowing. The list and burn‐list treatments resulted in similar infiltration. Water‐use efficiencies were similar for all treatments.At the end of the 5‐year study, soil organic matter content was lowest (1.66%) for burn‐lister tillage and highest (1.72%) for lister and disk tillage. Water‐stable aggregation was highest (84.5%) for rototilling and lowest (79.3%) for burn‐lister tillage. Bulk density increased in all plots, but it increased the least in plots that were moldboard plowed. Moldboard plowing resulted in the lowest (21.9) and burn‐lister tillage in the highest (28.6) percentage of fine aggregates (<0.42 mm). All treatments resulted in a relatively high percentage of wind‐erodible aggregates (<0.84 mm).Applying 135 kg N/ha maintained soil organic matter and total nitrogen at higher levels than did 90 kg N/ha. Applying N soon after harvest of the previous crop generally was as beneficial as applying N at seeding. Soil bulk density, water‐stable aggregation, and dry aggregate distribution were not significantly affected by fertilizer treatments.
Diurnal Soil‐Water Evaporation: Chloride Movement and Accumulation Near the Soil Surface
Authors: Nakayama F. S. , Jackson R. D. , Kimball B. A. , Reginato R. J. 
Published: July 2010

AbstractThe movement and accumulation of chloride at shallow depths (0 to 9 cm) in a bare soil following an irrigation were studied under field conditions. Chloride accumulation in the 0‐ to 0.5‐ and 0‐ to 1‐cm depth increments followed a diurnal pattern but out‐of‐phase from the soil water content during the first few days after irrigation. The diurnal amplitude of chloride decreased with time as the soil progressively dried. At the 1‐ to 2‐cm and deeper depths, diurnal cycling of the chloride content was not measurable, whereas cycling in the water content was evident. Most of the total chloride accumulation at the shallowest depth occurred in the early stages of drying. However, chloride movement was detected as low as 4% volumetric water content or approximately −1,000 bars soil water potential.
A Comparison Between Mercury Injection and Nitrogen Sorption as Methods of Determining Pore Size Distributions
Authors: Sills I. D. , Aylmore L. A. G. , Quirk J. P. 
Published: July 2010

AbstractA comparison of mercury injection and nitrogen sorption methods of pore size distribution analysis was made on a sample of goethite using the slit‐shaped pore model. Using the commonly accepted contact angle of 140° for mercury, the mercury pore‐size distribution plot is displaced by approximately 20% in plate separation with respect to the nitrogen plot. The assumption of a contact angle of 153° for mercury is required to make the plots coincide. This value is regarded as not unrealistic. Combination of the two techniques provide a useful method of pore size distribution analysis over a continuous range of pore sizes from 10Å to 50µm. This approach is particularly appropriate to the investigation of the pore structure of soil materials.
The Oxidation of Divalent Manganese Under Conditions Present in Tile Lines as Related to Temperature, Solid Surfaces, Microorganisms, and Solution Chemical Composition
Authors: Meek B. D. , Page A. L. , Martin J. P. 
Published: July 2010

AbstractThe oxidation and precipitation of Mn was measured in the laboratory under conditions similar to those present in tile lines. The presence of microorganisms capable of oxidizing Mn2+ was the most important factor controlling oxidation of Mn. These microorganisms were intimately associated with MnO2 collected from tile lines and could not be separated from the MnO2 particles. Hence, oxidation of Mn in the presence of microorganisms without the MnO2 could not be studied. Surfaces of sand or clay did not catalyze the oxidation. An increase in temperature from 20 to 30C increased the oxidation only slightly.The effects of dissolved oxygen, soluble organic carbon, total salt content, pH, and bicarbonate over the concentration ranges occurring in tile lines were determined using solutions containing manganese oxidizing microorganisms. Soluble organic carbon and total salt content have no significant effect on manganese oxidation. The percent oxygen in the gas mixture did not affect the oxidation rate when it was varied between 1 and 21%. When nitrogen was flushed through the cylinders, the zero oxygen resulted in solution of Mn2+ from the manganese dioxide. When the bicarbonate level was raised to 9.0 meq/liter (4% CO2), the oxidation rate was 3 times the rate at the 5.3 meq/liter level of bicarbonate.
Direct Vaporization and Quantification of Arsenic from Soils and Water
Authors: Melton James R. , Hoover William L. , Ayers Jo Lynn , Howard Peggy A. 
Published: July 2010

AbstractA procedure is described for the determination of arsenic in soils at the parts per million level and water at the parts per billion level. Determinations are made by direct introduction of arsine gas into the flame of an atomic absorption spectrophotometer. An easily constructed apparatus is described for introducing arsine into the flame. Soils from various states, as well as water samples from Texas waterways, are studied for arsenic content. Recoveries of arsenic added to soils and water samples ranged from 93.0 to 106.0%.
Formation of Dimethylnitrosamine, a Carcinogen and Mutagen, in Soils Treated with Nitrogen Compounds
Authors: Ayanaba Abateni , Verstraete Willy , Alexander Martin 
Published: July 2010

AbstractDimethylamine was formed from trimethylamine in a spodosol (pH 3.8), a silty clay loam (pH 5.8), and a silt loam (pH 6.5). Dimethylnitrosamine appeared if the soils were amended with the tertiary amine and nitrate or nitrite or with dimethylamine and nitrite. The amines were added to soil to a concentration of 50 and 500 ppm as nitrogen. The nitrosamine also was produced from the tri‐ or dimethylamine in the spodosol in the absence of supplemental inorganic nitrogen. The fungicide, thiram, was converted to dimethylnitrosamine in the spodosol treated with nitrate or nitrite. The identity of the nitrosamine was verified by ultraviolet spectrometry and thin‐layer and gas chromatography. Dimethylamine and dimethylnitrosamine disappeared with time from the soils.
Principles of Managing High Frequency Irrigation
Authors: Rawlins S. L. 
Published: July 2010

AbstractThe consequences of increasing irrigation frequency are explored, taking into consideration the laws governing water flow in soil. As frequency increases, the waterholding capacity of the soil becomes less important because water is supplied as the plants require it. Soil water content, and therefore matric potential, are continuously high and only slightly dependent upon deep percolation rate. This makes the need for deep percolation to leach salts the only valid criterion for applying more water than the plants transpire. The need to apply extra water to those crops that require high soil water content is eliminated. Controlling the deep percolation rate rather than the soil water status requires measurements of flux rather than water potential as inputs for managing the quantity of water to be applied.
Crop Residue, Soil Water, and Soil Fertility Related to Spring Wheat Production and Quality After Fallow
Authors: Black A. L. 
Published: July 2010

AbstractOver an 8‐year period, wheat straw mulch rates of 0, 1,680, 3,360, and 6,730 kg/ha were established each spring of the fallow year in alternate crop‐fallow blocks in three replications on a Dooley sandy loam. Fertilizer subplot treatments applied before seeding spring wheat (Triticum aestivum L.) were as follows: Check, N, P, and N plus P. Both elements were applied at a rate of 34 kg/ha; N was applied each crop year, and P was applied initially and every other crop year thereafter.After 14 and 21 months of fallow, average available soil water stored to a depth of 1.5 m increased significantly and was positively correlated with increasing residue levels. Each metric ton of surface residue increased average available soil water supplies 0.5 cm. Mean grain yields were positively correlated with stored soil water at seeding only when both N and P were applied. N‐P fertilization increased mean grain yields 410, 580, 690, and 760 kg/ha per year for corresponding residue levels of 0, 1,680, 3,360, and 6,730 kg/ha, respectively. A significant decrease in grain protein level associated with increasing residue level was caused by N dilution and was proportionate to the yield increases obtained with increasing residue levels within each fertilizer treatment. Residue treatments did not significantly influence total N uptake by grain plus straw at maturity. Grain protein levels could be increased and maintained near 15% with N or N‐P fertilization even though grain yield increased considerably.
Salts in Irrigation Drainage Waters: I. Effects of Irrigation Water Composition, Leaching Fraction, and Time of Year on the Salt Compositions of Irrigation Drainage Waters
Authors: Rhoades J. D. , Ingvalson R. D. , Tucker J. M. , Clark M. 
Published: July 2010

AbstractThe compositions of percolated drainage waters resulting from the use of eight synthesized river waters of the Western USA under conditions of alfalfa (Medicago sativa L.) production in a controlled lysimeter experiment are presented. The compositions are shown to be affected by (i) the composition of the river water used for irrigation; (ii) the fraction of applied water that appeared as drainage water; (iii) the presence or absence of soil CaCO3; (iv) whether or not the drainage water is open to the atmosphere, and (v) the time of year.
Air Entrapment as a Possible Source of Error in the Use of a Cylindrical Heat Probe
Authors: Nagpal N. K. , Boersma L. 
Published: July 2010

AbstractThe cylindrical heat probe is frequently used to measure the thermal conductivity of soils. Its theory is based on the assumption of zero thermal contact resistance at the probe surface. Noncompliance with this assumption could result from air entrapment at the probe surface, at the time of inserting the probe into the porous material. Results of studies are reported which show that the use of the heat probe can yield erroneous results which can be explained on the basis of air entrapment at the probe surface. Additional experiments were carried out to seek information regarding the relationship between thermal conductivity and soil water content for materials made up of different particle sizes. The porous media used consisted of three glass bead size fractions with diameters of 53–74, 74–105, and 149–210 µm obtained by dry sieving. Results of the experiments indicated that at the ambient temperature of 26C the relationship between thermal conductivity and water content was the same for the three size fractions. Experiments were not conducted at other ambient temperatures.
Nitric Oxide Sorption by Calcareous Soils: I. Capacity, Rate, and Sorption Products in Air Dry Soils
Authors: Prather R. J. , Miyamoto S. , Bohn H. L. 
Published: July 2010

AbstractAt room temperature, air dry calcareous soils sorbed from 0.5 to 2% NO by weight within 10 to 15 min from a dry air stream containing 1.6% NO by volume. The sorption capacity increased with 0.4 to 0.7‐th power of NO concentration and the soil specific surface and was independent of the soil acidtitratable basicity. The sorption rate was approximately proportional to the unused portions of the capacity with rate constants ranging from 0.4 to 1 min‐1. Less than 10% of sorbed NO was lost by heating at 105C or a suction of 65 cm Hg for 24 hours. The NO sorbed by the soil was converted to NO‐3.
Iron‐Induced Oranging Disease of Rice in Relation to Physico‐Chemical Changes in a Flooded Oxisol
Authors: Howeler R. H. 
Published: July 2010

AbstractSoil conditions associated with an oranging disease which occurs in flooded rice (Oryza sativa) grown on the Oxisols of the Llanos Orientales of Colombia were studied by measuring changes in pH, Eh, and Fe and Mn levels in soil solutions after flooding. It was found that rates of reduction and the build up of Fe in the soil solution vary greatly for different Llanos soils, between virgin and previously‐cropped soils, and between air‐dried and field‐moist soils. Levels of Fe in solution could be reduced by various water management treatments and by the addition of large amounts of lime or MnO2. It was observed that oranging symptoms occur as solution Fe concentration increases and that large plants were more seriously affected than small plants. Roots of affected plants were heavily coated with oxidized Fe and few active white roots formed after the increase in Fe concentration. The disease appears to be due to indirect Fe toxicity, i.e., an Fe‐induced deficiency of mainly P, K, Ca, and Mg. Due to the relatively high level of Fe in solution, the roots become coated with iron‐oxide reducing the root's capacity to absorb enough plant nutrients from an already deficient environment.Under certain conditions plants may also suffer from direct Fe‐toxicity, i.e., excessive Fe absorption by the plant, resulting in bronzing symptoms. A combination of direct and indirect Fe‐toxicity may produce plants with a wide range of intensities of oranging symptoms and brown streaks on the leaves.
Wind Erosion as a Factor in Soil Formation in the Pierre‐Shale Landscape of Western South Dakota
Authors: White E. M. 
Published: July 2010

AbstractSlopes exposed to the prevailing NW‐SE winds in the Pierreshale landscape of western South Dakota have been eroded at a slow rate when vegetation was either destroyed by fire or weakened by drought since at least the Pleistocene. Slopes protected from the prevailing winds have had negligible wind erosion except in areas where severe erosion created deflation basins. These blowout basins are limited to small interfluve areas, a few square miles in size, which probably had a thick layer of loose, sand‐size fissile‐shale fragments that winds could erode. Soils in areas with blowout basins usually are more weakly developed, have shale at shallower depth, have little or no gilgai development, and appear to be younger than soils in comparable areas without deflation basins. Thus, the soil age in these areas is less than would be predicted from the geomorphic relationships to Pleistocene terrace systems. Soils in one area with deflation basins have development comparable to soils derived from late‐Wisconsin drift.
Transfer of Heat by Conduction and Vapor Movement in a Closed Soil System
Authors: Westcot D. W. , Wierenga P. J. 
Published: July 2010

AbstractA study was made to determine the importance of vapor flow to the heat transfer process in soil. Soil temperature and water content were measured in sealed columns, 7.6 cm in diameter and 32 cm in length. The columns were inserted into a field plot and exposed to daily temperature fluctuations for periods varying from 1 to 6 days. A computer simulation model was developed to predict vapor movement and the transfer of heat by conduction and by vapor diffusion. Agreement was found between observed and computed water and temperature distributions in the columns. Comparison of observed and computed temperature profiles shows that for an accurate prediction of the soil temperature in the upper soil profile, heat transfer by vapor movement must be taken into account. Vapor flux accounted for 40–60% of the heat flux in the surface 0–2 cm of the soil profile during periods of the day. Vapor flux past the 11‐cm depth, depending on the time of the day, accounted for 17–34% of the total heat flux. Vapor flux still accounted for 20–25% of the total heat flux at the 25‐cm depth although the total heat flux density was no more than 10% of its surface value.
Oxidation of Ammonium to Nitrate in a Soil Column
Authors: Ardakani M. S. , Rehbock J. T. , McLaren A. D. 
Published: July 2010

AbstractA mathematical model based on Michaelis‐Menten kinetics for oxidation of ammonium to nitrate during downward flow in a column of soil mixed with sand has been tested. First the column was perfused with nitrite to stimulate the growth of nitrite oxidizing microorganisms in order to decrease the concentration of nitrite at any time in the column during subsequent perfusion with ammonium. The nitrite oxidizers multiplied in a quasilogistic fashion to nearly maximal numbers, exceeding ammonium oxidizers by at least a factor of 102. After a population density of 103/cm3 was reached for NO2‐ oxidizers, the column was perfused with ammonium solution; in a steady state the ammonium concentration decreased with depth (proportional to time of flow) in accord with Michaelis‐Menten kinetics. The rate constants for oxidation of NH4+ were proportional to the numbers of ammonium oxidizing microorganisms extant at any given time of observation; these numbers increased exponentially at first but leveled off after about 3 weeks of continuous perfusion of the column.As expected, the decline of ammonium concentration with depth during solution flow just equalled the appearance of nitrate with very low concentrations of nitrite in the steady state. From the data the normalized rate constant is 4.5 × 10‐3 ppm cm3/hour per microbe at room temperature, about five times greater than the corresponding figure for nitrite oxidation.
A Simple and Quantitative Greenhouse‐Laboratory Method for Injecting Gases into Soils
Authors: Hill Walter A. , Bohn Hinrich L. 
Published: July 2010

AbstractA simple, rapid, and safe procedure for measuring ammonia gas accurately and injecting it into soils is described. The apparatus is easily assembled from readily available and inexpensive materials and could be used for many gases. The method is useful for laboratory, greenhouse, and classroom work.
Isolation of Soil Particle‐Size Fractions
Authors: Genrich D. A. , Bremner J. M. 
Published: July 2010

AbstractStudies of the properties of soil particle‐size fractions have been restricted by the lack of a method of quantitatively isolating these fractions without serious modification of their properties. A mild method of isolating soil particle‐size fractions for such studies is described. It involves dispersion of the soil by ultrasonic vibration in water and subsequent isolation of the particle‐size fractions by sieving, centrifugation, and filtration techniques. The method allows large‐scale isolation of soil particle‐size fractions without use of chemical reagents, and it gives almost quantitative recovery of soil material in the fractions isolated. Data reported show that the particle‐size distribution values obtained for 13 soils after isolation of sand, silt, and clay fractions by the method described agreed closely with those obtained by particle‐size analysis after chemical dispersion by the peroxide‐sodium polyphosphate method.Clay fractions isolated from soils by the physical method described had higher carbon, nitrogen, sulfur, and phosphorus contents and contained markedly higher percentages of the total carbon, nitrogen, sulfur, and phosphorus in the soils fractionated than did clay fractions isolated by another physical method that did not quantitatively separate clay‐size material.