bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein and Free Amino Acid Composition of Sesame Meal as Affected by Nitrogen, Phosphorus, and Potassium Nutrition
Authors: Mitchell G. A. , Bingham F. T. , Labanauskas C. K. , Yermanos D. M. 
Published: July 2010

AbstractProtein and free amino acid composition of lipid‐free sesame (Sesamum indicum L.) meal was studied for effects of increasing substrate levels of N, P, and K in sand culture experiments. Concentrations of individual protein amino acids were increased in the seed meal with increasing substrate levels of N and K nutrition due primarily to increases in protein content. Increasing P supply had no significant effect on amino acid composition.Increasing levels of N resulted in increases in nonamino acid forms of N. Nitrogen increased individual free amino acids while P had no effect. Potassium deficiency resulted in accumulations of all individual free amino acids except cystine. These accumulations coupled with the observed decreases in protein amino acids in K‐deficient plants support the view that adequate K supply is required for proper utilization of amino acids in protein synthesis.The pattern of essential amino acids expressed as a fraction of the total essential amino acids was little affected by N, P, and K nutrition when compared to the large increases resulting from increased seed yield and meal protein content.
Variability of Hydraulic Conductivity in Two Subsurface Horizons of Two Silt Loam Soils
Authors: Baker F. G. , Bouma J. 
Published: July 2010

AbstractHydraulic conductivity was measured in the B22t and B31t horizons of 12 pedons of two soils developed in loess deposits overlying glacial till. Conductivity measurements were made with the crust test technique for unsaturated conditions and with a new related in situ method for saturated conditions. Nonlinear regression yielded simple well‐fitting curves of the form log K = log(bψ‐c). Variability within and between major horizons in these soil series was found to be relatively low. The four horizons in these two silt loam soils had statistically identical hydraulic conductivity characteristics, even though morphological soil structure and soil genesis differed significantly.
Sampling the Unsaturated Zone in Irrigated Field Plots
Authors: Pratt P. F. , Warneke J. E. , Nash P. A. 
Published: July 2010

AbstractData obtained from samples from each of 10 holes/plot for one plot from each of three soils were subjected to statistical analysis and used to formulate plans for sampling the 1.5‐ to 4.5‐m depth of 48 experimental plots that had received animal manures. The statistical analysis of these three plots suggested that 10 holes/plot and 10 samples/hole would provide plot means within about 20% of the true means for nitrate and chloride concentrations and electrical conductivity of saturation extracts, ECe, except for one soil which had residual salts in highly variable concentrations at the 3.0‐ to 4.5‐m depth. The sampling procedure developed gave satisfactory results when statistical analysis of the effects of manure treatments, soils and irrigation levels on nitrate, chloride and ECe were measured.
Sulfuric Acid for the Treatment of Ammoniated Irrigation Water: II. Reducing Calcium Precipitation and Sodium Hazard
Authors: Miyamoto S. , Ryan J. 
Published: July 2010

AbstractEffects of ammonia (NH3 or NH4OH) and sulfuric acid (H2SO4) applied to ammoniated water on Ca precipitation and Na‐hazard of irrigation water are evaluated theoretically using known relations of ion equilibria and tested with laboratory and greenhouse experiments. Results show a severe precipitation of Ca2+ when ammonia is applied to alkaline irrigation waters. At ammonia rates ranging from 25 to 100 mg/liter, for instance, 80 to 95% of Ca2+ present in water may precipitate as CaCO3 even under a closed system. Ammonia application also increases exchangeable Na and NH4, and can reduce water infiltration rates, especially when irrigation waters contain high Na+ relative to Mg2+ and Ca2+. Sulfuric acid applied to ammoniated water neutralizes OH‐ produced by ammonia application. Thus it reduces Ca precipitation and exchangeable Na, and consequently prevents a decline in infiltration rates. Sulfuric acid, which is now available as a pollution abatement byproduct in the Southwest, can be used for correcting excessive lime incrustation or poor water penetration induced by the use of anhydrous or aqua ammonia without corroding irrigation systems.
Thermodynamic Stability and The Law of Corresponding States in Swelling Soils
Authors: Sposito Garrison , Giráldez Juan V. 
Published: July 2010

AbstractFollowing a heuristic suggestion by Groenevelt and Parlange, a thermodynamic description is given of a postulated order‐disorder transformation in a swelling soil. This transformation is shown to correspond to a phase transition of the second order at the air entry point, wherein the onset of a microscopic ordering process among the clay crystals in the soil occurs and there is a consequent discontinuity in the slope of the swelling curve. The available experimental swelling curves with which this prediction can be checked are organized on the basis of a new application of the law of corresponding states that permits all of the data to be plotted as a single, universal function of a reduced gravimetric water content variable. Scatter in the swelling curve data is sufficiently great at present to preclude a definite conclusion as to whether a second‐order phase transition actually occurs in swelling soil.
Electric Charges on Sesquioxidic Soil Clays
Authors: Fey M. V. , le Roux J. 
Published: July 2010

AbstractThe effects of pH, phosphate, oxalate, pyrophosphate, citratedithionite‐bicarbonate and Na2CO3 pretreatments on the positive and negative exchange charges of sesquioxidic clays from soils of South Africa, Australia, Brazil, Japan, and New Zealand were measured using 0.05N KCl as index electrolyte according to a method which obviates a washing step for removal of excess salt prior to replacement of the index ions, Behavior of clays rich in allophane was compared to that of three synthetic amorphous, aluminosilica gels.Hysteretic, pH‐dependent net negative exchange charge appears to arise from positive exchange charge hysteresis only, CEC being fully reversible by titration with strong acid.The methodology of cation and anion exchange capacity determinations is discussed with special reference to the problem of surface charge density variations encountered in different materials.
Potassium Release from Sand, Silt, and Clay Soil Separates
Authors: Munn D. A. , Wilding L. P. , McLean E. O. 
Published: July 2010

AbstractFour Ohio soils of divergent mineralogy were fractionated into sand, silt, and clay‐sized separates after dispersion with an ultrasonic probe. Samples were extracted for 10 days with 0.01M CaCl2 with the solution being changed each day. There was a wide range in daily and cumulative K release among the four soils for the same particle size and for different particle sizes within the same soil. When weighted according to particle size distribution of the soil, the clay was found to contribute 30–74%; silt 24–56%; and sand 3–21% of the total K released by the sum of the three separates. In all four soils, the clay separate released the most K per unit weight. The apparent rate constants for K release from the sand and clay separates were similar and renerally higher than that for the silt separates.
Particle‐Size Distribution Characterization for the Coarse Fraction of a Granite Soil: II. Disintegrating Granite
Authors: Russell D. A. 
Published: July 2010

AbstractThe object of this study was to test the incomplete gamma function previously developed as a descriptor for grapite disintegration. Samples of disintegrating granite were taken from several sites at three locations in a hot semiarid environment in south‐central Africa (southern Rhodesia). These samples were from surface rock, profile corestones, and disintegrating rock at the base of the soil profile. Particlesize distributions were obtained using the standard sieving and pipette method. For materials > 10 mm, Martin's diameter was measured directly.The incomplete gamma function was fitted to these data, and also to U.S. and French data from the literature, for granite in an apparently similar state of disintegration. The values for the degree‐of‐disintegration parameter were fairly uniform. The mode of disintegration appeared the same regardless of site. The two‐parameter incomplete gamma distribution was found to be a reasonably good descriptor of the particle‐size distribution of disintegrating granite. The mean size appeared to be a sensitive and useful single‐valued descriptor for these distributions.
Particle‐Size Distribution Characterization for the Coarse Fraction of a Granite Soil: III. The Coarse Fraction of a Granite Sand
Authors: Russell D. A. 
Published: July 2010

AbstractThe object of this study was to test the previously developed two‐parameter incomplete gamma function as a descriptor for the > 0.002‐mm fraction of some semiarid, sandy, granite‐derived soils from south‐central Africa (southern Rhodesia). Samples were taken from profiles at five locations. Three of these locations had been previously selected for sampling disintegrating granite, and one was a medium rainfall site. Particle‐size distributions were obtained using the standard sieving and pipette method. For materials > 10 mm Martin's diameter was measured directly. The incomplete gamma described the data reasonably well. The two distribution parameters, α, the weathering index, and ρ, the scale factor, varied as expected. The mean and standard deviation increased with depth as expected. On the basis of the behavior of ρ the profiles tested were separated into two groups. Grouping according to the variation of α yielded the same two groups. The difference between the two groups could perhaps be the degree of development. However, more comparisons are necessary to check this.
High‐frequency Irrigation for Water Nutrient Management in Humid Regions
Authors: Phene C. J. , Beale O. W. 
Published: July 2010

AbstractA water‐nutrient management method was designed to prevent plant‐water and nutrient stresses while maximizing the available soil water storage to accommodate rainfall. This method minimized the need for the soil as a storage reservoir for water and nutrients by frequently irrigating a portion of the root zone with small amounts of water and nutrients. The optimal range of soil matric potential, based on soil oxygen diffusion rate, soil strength, water desorption characteristics, and unsaturated hydraulic conductivity was used to determine high‐frequency irrigation criteria for sweet corn (Zea mays L.). Trickle‐irrigated plots yielded 12 and 14% more corn than did the furrow‐ and sprinkler‐irrigated plots. When fertilizers were broadcast and banded, soil NO3‐N profiles measured near the end of the growing season showed that, compared to furrow and sprinkler irrigation, trickle irrigation reduced NO3‐N losses from the root zone.Optimal ear yield was produced with high‐frequency trickle irrigation when the soil matric potential at the 15‐cm soil depth was controlled at about −0.2 bar and plants were fertilized with 168 kg/ha each of N and K. Ear yield for this treatment was 66% higher than that for nonirrigated corn fertilized at the same rate. Soil NO3‐N did not accumulate in the profile with depth and time in plots fertilized at the 168‐kg/ha rate, but did accumulate in plots fertilized with 336 kg/ha. Generally, plots trickle‐irrigated with fertilizer solution had a higher soil NO3‐N content on the row than 50 cm from the row.The results of this research indicate that water use efficiency, N‐use efficiency, and N leaching can be controlled in sandy soils when N and K are applied with high‐frequency trickle irrigation systems and N and K rates are adjusted to maintain an optimal N‐level in corn plants.
Relation Between the Kinetics of Nitrogen Transformation and Biomass Distribution in a Soil Column During Continuous Leaching
Authors: Starr J. L. , Parlange J.‐Y. 
Published: July 2010

AbstractNitrogen concentration profiles in soil columns with associated microbial distributions have been used in the past to deduce the kinetics of nitrogen transformations during steady leaching. Owing to the many factors which control microbial reaction kinetics in continuous flow systems, the effect of biomass variation and order of reaction cannot be separated by simply measuring steady‐state concentrations profiles. It is shown here that in practice these measurements only lead to some average kinetics for the system observed, even when the microbe distribution is measured independently. Previously published experimental data in conjunction with a derived expression are used to illustrate the point.
Coupling Phenomena in Saturated Homo‐ionic Montmorillonite: I. Experimental
Authors: Elrick D. E. , Smiles D. E. , Baumgartner N. , Groenevelt P. H. 
Published: July 2010

AbstractA series of experiments was performed to observe the effects of salt concentration differences across a thin layer of homo‐ionic montmorillonite. The water pressure difference, concentration difference, and voltage difference measured with electrodes reversible to the anion were observed as functions of time. A qualitative explanation of the observations is proposed.
Radiation Hazard from Americium‐Beryllium Neutron Moisture Probes
Authors: Gee G. W. , Stiver J. F. , Borchert H. R. 
Published: July 2010

AbstractNeutron fluxes from shielded neutron moisture probes need to be measured to evaluate total radiation exposure from these instruments. Theoretical considerations suggest that for 100 mCi Am‐Be neutron moisture probes the fast neutron flux can be relatively high and contribute significantly to the radiation exposure of probe operators.Measured radiation dose levels at the surface of 100 mCl Am‐Be neutron probes manufactured by Troxler Laboratories were found to be as high as 37m Rem hours‐1 which exceeds reported levels by as much as 38 times. This is likely due to nonreporting of fast neutron fluxes. Conventional field use of these probes may present a radiation hazard to operators if the probe is hand carried for periods which exceed 3 hours/week. The probe should be transported to and from sites inside a wooden storage crate and be kept at least 1 m from personnel. To improve the radiation safety factor for on site use we recommend a hand cart to transport the probe.
Heat and Water Movement Under Surface Rocks in a Field Soil: I. Thermal Effects
Authors: Jury W. A. , Bellantuoni B. 
Published: July 2010

AbstractResults of a field experiment designed to evaluate the effect of surface rocks on soil heat flow are presented. Temperature observations were made by thermocouples at 12 locations under and adjacent to rocks placed over bare soil. Continuous readings were taken for 24‐ and 48‐hour intervals using seven different kinds of rock cover, ranging from large granite slabs to gravel piles, during the time between December 1974 and August 1975.Experimental results consistently showed a nonnegligible 24‐hour net horizontal heat flow toward the rock at both the 2.5 and 5.0 cm depth. Net vertical heat flow was always downward in the soil under the bare surface, but was observed to be either upward or downward in the soil under the rock cover depending on prior conditions. Because water vapor movement in moist soil is generally in the same direction as heat flow it was suggested that surface rock cover may be a mechanism for water collection in arid climates.A simulation model was constructed to describe two‐dimensional heat flow in a uniform soil with a rectangular rock on the surface. Using the measured surface temperature as boundary values and a soil thermal conductivity corresponding to the mean daily soil surface temperature, the simulation model adequately reproduced the observed temperatures under and adjacent to the rock.
The Effect of pH, Salt Concentration, and Nature of Electrolytes on the Charge Characteristics of Brazilian Tropical Soils
Authors: Morais F. Ilton , Page A. L. , Lund L. J. 
Published: July 2010

AbstractA study of the distribution of electric charges in the A and B horizons of some Oxisols, Ultisols, and Alfisols from Brazil was made by direct measurement of retention of ions in the presence of varying electrolyte concentrations. Soil samples were collected from the Amazonian Jungle and from the principal cocoa‐producing zone of the country, the southern part of Bahia State.The electrochemical behavior of these soils was found to be similar to that of the constant potential systems in which the surface potential is determined by H+ and OH‐ ions in the equilibrium solution, hence charge distribution varied substantially with pH and electrolyte concentration. Direct measurement of adsorption of ions from solutions of MgSO4, K2SO4, KCl, and MgCl2 showed that the nature and valence of the counter‐ions also influenced the magnitude of the electric charges on the soil particles. The pH at the zero point of charge (ZPC) of the soils varied from 1.2 to 3.4 in the A horizons and from 4.0 to 6.1 in the B horizons. At or near their field pH the surface horizons were, in general, net negatively charged, while the subsurface horizons were either isoelectric or positively charged. This fact was found to be related to differences in organic matter contents of the horizons.
Relation of Nonexchangeable Potassium and Magnesium to Development in Some Midwestern Soils
Authors: Kovar J. A. , Riecken F. F. 
Published: July 2010

AbstractThe nonexchangeable (NEx) potassium and magnesium status of the <1µm clay and other properties of the thin loess over till soils of northwestern and eastern Iowa were investigated to better understand the genesis and morphology of these soils and to provide a firmer basis for classification of this recently delineated group of soils. These soils are compared with similar soils from Illinois and Ohio to evaluate the regional effects of parent materials, vegetation, and climate.The Sac and associated soils from northwestern Iowa have a higher NEx K and Mg content, are less texturally developed, release more K with sodium tetraphenylboron, and have a higher illite content than the Dinsdale and associated soils from eastern Iowa. These differences are attributed to the less weathered condition of the northwestern Iowa soils, primarily because of the lower mean annual precipitation (MAP) in that area. These differences support the separation of the two groups of soils at the series level.The loess‐derived upper sola of the forested Iowa soils have about the same NEx K and Mg contents, but more illite, and are less texturally developed than the upper loess portion of the forested Illinois and Ohio soil profiles. The lower‐till‐derived sola of the Iowa soils have a lower NEx K, NEx Mg, and illite content than the Illinois and Ohio soils. These differences in characteristics support the separation of the Iowa thin loess over till soils from the Illinois and Ohio thin loess over till soils at the series level.
Analysis of Soil Variability with Repetitive Aerial Photography
Authors: Milfred C. J. , Kiefer R. W. 
Published: July 2010

AbstractRepetitive aerial photography can be used to help identify and evaluate variation within soil mapping units. An area of approximately 12 ha (30 acres) was photographed from a light plane with two 35‐mm cameras using color and color infrared film on 20 different dates from May through November 1969. This sequence of aerial photographs recorded changes in surface soil moisture patterns and documented a close correlation to patterns of differences in growth and maturation of corn (Zea mays L.) that were visible later on during the growing season.Field investigation of soil profiles in the study area established the relationship of these patterns of surficial soil moisture and crop growth to variations in soil profile characteristics, especially depth of solum, thickness of silt mantle and soil drainage class. The yield of ear corn associated with delineated areas of crop and soil patterns ranged from 5,865 to 9,087 kg/ha. Differences in crop growth and yield were attributed to variations in the amount of available soil moisture, as influenced by soil profile characteristics and surface topography.
Sampling the Unsaturated Zone of Irrigated Lands for Reliable Estimates of Nitrate Concentrations
Authors: Rible J. M. , Nash P. A. , Pratt P. F. , Lund L. J. 
Published: July 2010

AbstractData from a study of 56 field sites were used to examine the variability of nitrate‐nitrogen concentrations in the unsaturated zone underneath the root zone. The specific data were nitrate‐nitrogen concentrations in soil water in samples taken at 0.9‐m intervals from the 4.5‐ to 11.9‐m depth from four holes per site. Analyses of variance of these data provided estimates of variances that were used to predict the depth sampling interval and the number of holes required for site means to be within confidence limits of 10, 20, and 30%. Calculations were based on sampling intervals of 0.9, 0.6, and 0.3 m providing 9, 13, and 26 samples per hole, respectively. Relationships developed between number of sites, number of holes required, sampling interval, and confidence limits were used to test selected sampling plans for degree of precision in comparison with the actual sampling procedure. A cost analysis of the field study indicated that it would cost three to four times more than the field study to use a sampling plan which would reasonably ensure that 75% of the sites' true means fall within 20% of the measured means at a confidence level of 95%.
A Method for Sectioning Saturated Soil Cores
Authors: Reddy K. R. , Patrick W. H. 
Published: July 2010

AbstractA simple system for sectioning water‐saturated cores without prior freezing is described. The method described can be used for studying the distribution and movement of ions in soil or sediment cores prepared in the laboratory or obtained in undisturbed form from the field. The average coefficient of variation was 4.8% for the sectioning of the cores prepared in the laboratory and 10.5% for the sectioning of the cores obtained from the field.
Tile Drainage in Bedded Soil or a Draw
Authors: Powell Norris L. , Kirkham Don 
Published: July 2010

AbstractThe process of shaping flat land by plowing it into a series of ridges separated by parallel dead furrow is called bedding and the ridge‐furrow systems are called beds. The furrows are supposed to remove surface water from the ridges, but often do not. In this paper the amount of water that can be removed by tile if they are placed under the furrows is computed on the basis of Darcy's law and potential theory. In the analysis, water‐saturated, steady‐state conditions and a subsurface barrier on which the drain tile are laid are assumed. For a poorly drained prairie soil, the calculations show that tile (or plastic tubes, etc.) placed 0.35 m below the furrow bottoms and 30 m apart in beds of 2% slope will remove 5 mm of water/day, and that the bed furrows would have to remove an additional 4.52 mm/day to take care of an expected drainage coefficient of 9.52 mm/day. For general use, 28 depth and spacing geometries are analyzed and tabulated for amounts of flow to tile in the beds. For certain geometries, some of the recharge rainfall seeps in and out of the ridge slope before the water seeps down again into the soil. This in and out seepage occurs for small tile depths, and small tile sizes. Flow nets are presented. It is shown that the theory applies to the drainage of a draw.