bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Partial Pressure of Oxygen on Denitrification in Soil
Authors: Allison F. E. , Carter J. N. , Sterling Luann D. 
Published: July 2010

AbstractLaboratory experiments with Branchville sandy loam fertilized with nitrate salts showed that only trace losses of nitrogen occurred by denitrification when small samples were kept in air at approximately ⅓ atm. moisture content. This was true in both the presence and absence of up to 1% glucose or 2% wheat straw. When soils were aerated for 1 to 3 weeks with nitrogen gas containing 2.27% oxygen the losses of nitrogen were significant in about half of the tests and not in the others. When the oxygen partial pressure was only 0.46% the losses of nitrogen were as high as 10% of the added nitrate in the absence of any energy source and 50% in the presence of 0.5% glucose. Although appreciable denitrification did not occur until the oxygen partial pressure was much reduced, it is pointed out that under field conditions some denitrification would be expected at times even in open, well‐drained soils.
The Determination of Available Sulfur in Soils
Authors: Kilmer Victor J. , Nearpass D. C. 
Published: July 2010

AbstractA laboratory procedure was sought which would determine available sulfur in soils. As finally evolved, the method consists of extracting the sulfur with 0.5M NaHCO3 at pH 8.5 and determining sulfur in the extract by the Johnson‐Nishita procedure. Sulfur determined in this manner correlated very well with sulfur “A” values, an “r” value of 0.89 being obtained for 30 surface soils. Soils having < 10 ppm. S as determined by the proposed procedure generally responded to applications of sulfur.
Influence of Neutral Salts on the Phosphate Ion Concentration in Soil Solution
Authors: Clark J. S. , Peech Michael 
Published: July 2010

AbstractCertain cation activity ratios and ion activity products involving Ca++, H+, K+ and H2PO4‐ were found to remain constant in soil and clay suspensions as the electrolyte concentration was increased. The observed constancy of the cation activity ratios could be attributed to the fact that the concentrations of the cations on the surface of the soil particles remained constant under the conditions of the experiments. The constancy of the ion activity products involving Ca++, H+, K+, and the H2PO4‐ ion could be explained either by assuming that the phosphate ion is coadsorbed with exchangeable cations on the soil particles or by postulating the existence in the soil of any crystalline phosphate compound having a definite solubility product.
Chemical Extraction and Crop Removal of Manganese from Air‐Dried and Moist Soils
Authors: Hammes Jack K. , Berger K. C. 
Published: July 2010

AbstractOats were grown in the greenhouse on 20 different soils which had been stored in a moist condition prior to potting. Available soil Mn was estimated by extraction with 1.5M NH4H2PO4, 1.0N H3PO4, and 0.1N H3PO4 on moist as well as air‐dried soil samples. Correlations with soil and plant Mn showed that extraction of soil Mn from the moist samples with 0.1N H3PO4 gave the highest correlation coefficient (0.848). Other extractants resulted in much lower correlation coefficients (0.311 to 0.694), regardless of the sample moisture condition.In a second greenhouse experiment, oats were grown on seven soils which had been stored under air‐dry as well as moist conditions. With one exception, the amount of Mn removed by the oats grown on the previously air‐dried soils was equal to or greater than the Mn removed from soils previously stored in a field moist condition.Chemical extraction of soil Mn from moist as well as air‐dried soils revealed that the release of Mn upon drying requires aerobic conditions and is not a simple dehydration phenomenon. Extractions of moist as well as air‐dried samples with 0.1N H3PO4, 0.05M NaEDTA of pH 9.5, and 0.2% hydroquinone were performed to estimate the weakly acid‐soluble, organic, and easily reducible oxides of soil Mn, respectively. The results indicated that the release of Mn upon air drying stemmed from the organic fraction of soil Mn. This release of organically complexed Mn is thought to be a result of chemical oxidation of soil organic matter.
Comparison of Phosphate Sources for Alfalfa on a Calcareous Soil
Authors: Stanberry C. O. , Fuller W. H. , Crawford N. R. 
Published: July 2010

AbstractAn evaluation of phosphate sources for alfalfa production was made on P‐deficient Superstition fine sand under arid conditions. Factors studied included particle sizes, and methods, rates, and frequencies of application. These factors were evaluated under field conditions in terms of (a) hay yields, (b) P composition of plants, (c) total P removed from the soil by the hay, and (d) estimated residual P in the soil over a 3‐year cropping period using radiophosphorus techniques.Supplemental P applications increased hay yields an average of 38%, P percentage 25%, P yield 66%, and A values or residual P, 126%.A 3‐year summary demonstrated consistently that dicalcium phosphate, if mixed thoroughly with Superstition soil, was at least as efficient as concentrated superphosphate in increasing alfalfa hay yields, P percentage of the hay, total P removed from the soil, and available residual P. The two particle sizes of dicalcium phosphate were equally effective for the 3‐year period, but the finer, with greater surface area, appeared more efficient the first year.The higher rate of application, 131 pounds P per acre, was 7 to 71% more effective than the 66‐pound rate in increasing yield, P percentage, P yield, and A values. A single initial P application for the 3‐year period was as effective as the same total amount applied annually. When applied properly, both particle sizes of dicalcium phosphate, the phosphoric acid, and concentrated superphosphate all appeared to be satisfactory phosphate sources.
Field Studies of a Clay‐Enriched Horizon in the Lowest Part of the Solum of Some Brunizem and Gray‐Brown Podzolic Soils in Illinois
Authors: Bartelli L. J. , Odell R. T. 
Published: July 2010

AbstractThe morphology, range in expression, and occurrence are described of a clay‐enriched layer (Beta horizon) found below the B2 horizon of selected soils in the area of Wisconsin glaciation in northern Illinois. The Beta horizon, characterized by a darker color and an abrupt, irregular lower boundary, was more pronounced in coarser textured drift, in Gray‐Brown Podzolic soils, and in well‐drained members of soil catenas.
Chloride Diffusion in Soils as Influenced by Moisture Content
Authors: Porter L. K. , Kemper W. D. , Jackson R. D. , Stewart B. A. 
Published: July 2010

AbstractChloride diffusivities were measured in medium‐ and fine‐textured soils at moisture tensions from 1/3 to 15 atm. Chloride diffusivities obtained from the soil systems were divided by the diffusivity of chloride in water to obtain transmission factors. These factors varied from 0.310 to 0.027 depending on the soil moisture content and soil texture. The results were interpreted in terms of volumetric moisture content, effective path length factors and clay‐water interactions.
Test of Two Methods for Measuring a Labile Fraction of Inorganic Phosphorus in Soils
Authors: Van Diest A. , Jespersen H. W. , White R. F. , Black C. A. 
Published: July 2010

AbstractMeasurements of the phosphorus extracted from samples of 70 soils by the 0.03N NH4F, 0.025N HCl method of Bray and Kurtz and the anion‐exchange resin method of Amer and co‐workers were used as the basis for predicting the yields of phosphorus in plants grown on the soils in the greenhouse. The latter method gave the more precise prediction, but the regression coefficient was smaller for alkaline soils than for acid soils. No distinction between acid and alkaline soils was necessary where the regression of the yield of phosphorus was calculated on the H2PO4‐ and HPO4= taken up from the soils by the resin. The closest agreement between observed and calculated yields of phosphorus in the test plants was obtained with an equation based on the kinetics of phosphorus absorption by plants.
Calcium and Magnesium Determinations by EDTA Titrations
Authors: Tucker B. B. , Kurtz L. T. 
Published: July 2010

AbstractA comparison was made of four methods for the determination of magnesium by titration with EDTA (disodiumdihydrogen‐ethylenediaminetetraacetate).The first method consisted of three steps: (a) estimation of the sum of calcium plus magnesium by EDTA titration to EBT (Eriochrome Black T) endpoint, (b) estimation of calcium by EDTA titration to murexide endpoint, and (c) estimation of magnesium by subtracting (b) from (a).The other three methods consisted of direct titrations (d) of mangesium with EDTA to the EBT endpoint after calcium had been removed. If desired, calcium could then be estimated by subtracting the magnesium titration (d) from the titration for calcium plus magnesium (a).For removal of calcium, three precipitation procedures were compared. These precipitations were by sulfate in alcoholic solution, by tungstate, and by oxalate. As compared in these experiments, the four methods listed in order of over‐all accuracy were tungstate > sulfate > indirect > oxalate. The indirect procedure is the most simple and rapid. Of the precipitation procedures, the tungstate is the most rapid because the precipitation and titration are carried out at the same pH and thus only one buffer is required.
Soil Organic Matter: II. Studies of the Origin and Chemical Structure of Soil Humic Acids
Authors: Johnston Harry H. 
Published: July 2010

AbstractSmall quantities of soil humic acids were supplied to cultures of Nostoc muscorum, resulting in stimulation of growth and nitrogen fixation. Various organic compounds were added to compare stimulations and structural relationships. Of all the compounds tested, catechol and humic acids were found to give the greatest increases of nitrogen fixed. Part of the increase in nitrogen fixation was thought to be due to boron contained by the humic acids. Lignin oxidized by H2O2 and microorganisms was analyzed by infrared spectroscopy. The product formed by microorganisms gave a material with similar paper electrophoretic mobility as natural humic acids. Controlled degradation of humic acids and lignin gave various phenols. Humic acid chromatograms showed four phenols present: catechol, phenol, guaiacol, and o‐cresol. One spot found in the humic acid chromatograms has not yet been identified. Bean root lignin when subjected to the same degradation gave a spot in the same position and with the same color. Guaiacol and phenol were also identified from bean root lignin.
A Classification of ca Horizons in Soils of a Desert Region, Dona Ana County, New Mexico
Authors: Gile Leland H. 
Published: July 2010

AbstractA ca horizon is defined in the Soil Survey Manual as an accumulation of calcium carbonate. Field study in Dona Ana County, New Mexico shows that ca horizons occur in soils on a variety of sediments and geomorphic surfaces. A broad fan piedmont extends from the Rio Grande Valley eastward to the igneous Organ Mountains. To the north there is a desert bolson. In soils on these surfaces and in paleosols underlying the fan piedmont, ca horizons occur and range from thin CaCO3 coatings on pebbles or few CaCO3 filaments to indurated horizons many feet thick.In soils of the study area, ca horizons have been classified as weak, moderate, strong and very strong. The classification is based on field morphology and pertinent laboratory data, including CaCO3 equivalent, particle size distribution, bulk density, unconfined compressive strength and infiltration rate.
Caliche in Southwestern Idaho
Authors: Stuart Darrel M. , Fosberg M. A. , Lewis G. C. 
Published: July 2010

AbstractDeposition of caliche in the soils of southwestern Idaho probably results from soil‐forming processes. Caliche occurring on the lower, intermediate, and upper terraces of the Boise and Snake Rivers is described. Close correlation of the present ground surfaces with the top surfaces of the caliche layers is found. The pedogenic development of the soils is related to the ages of the terraces on which the soils occur, and also to the thickness and induration of the caliche layers. The thickness of the Cca horizon decreases or disappears entirely as the age of the soil and terrace increases. Calcium carbonate and silicates increase in the caliche horizons as the soils and terraces increase in age.
Soil Moisture Trends Following Thinning in Shortleaf Pine
Authors: McClurkin D. G. 
Published: July 2010

AbstractIn 19‐year‐old shortleaf pine plantations in northern Mississippi, thinning markedly increased available soil moisture in the middle and latter part of the growing season. In the second year after thinning the moisture increase was associated with more rapid and more prolonged diameter growth. Regardless of the amount of moisture available, diameter growth rates decreased during periods of rapid soil moisture depletion.
Tile Drainage for Layered Soil
Authors: Evans D. D. , Ashcroft Gaylen 
Published: July 2010

AbstractThe effect of a restricting layer (1 foot thick) on the flow of water to drain tiles has been evaluated by the relaxation method using a digital computer to perform the calculation. The following factors were varied alone and in combination: (a) depth to the restricting layer, (b) relative conductivity of the restricting layer to the surrounding soil, and (c) the depth of the drain. For all cases, a constant hydraulic head was assumed along the soil surface and within a gravel envelope surrounding the tile. An impermeable layer was considered to exist at 7 feet.Drain flux was calculated for each case and compared to give the relative effectiveness of the drains at the selected depths. There is nearly a linear relationship between drain flux and depth of drain when the relative conductivity of the restricting layer to the surrounding soil is 1:10. For 1:100 and 1:1000 conductivity ratio cases, drain flux is nearly independent of depth. The surface intake rate distribution is presented for several cases. The calculations show that a sizeable tension extending over a large portion of the soil profile would be expected for several of the cases.
Origin of a Surficial Deposit in Soils of Eastern Fulton County, New York
Authors: Arnold R. W. , Cline M. G. 
Published: July 2010

AbstractThe origin of a loamy surficial deposit within the sola of Sols Bruns Acides on glacial till in an area adjacent to the Adirondack Mountains of New York was investigated by field studies, mechanical analysis, and microscopic study. Field criteria strongly support an eolian origin, but cumulative particle‐size curves are unlike those of typical loess. Both cumulative curves and degree of grain frosting resemble mixtures of material from silty lacustrine deposits and glacial till in the same area. It was concluded that the surficial deposits are mixtures of fines from nearby areas of glacial till and lake sediments transported partly by saltation and partly by suspension through wind action.
Phosphorus Absorption by Corn Roots as Affected by Moisture and Phosphorus Concentration
Authors: Olsen S. R. , Watanabe F. S. , Danielson R. E. 
Published: July 2010

AbstractThe relative uptake of P by corn seedlings was 100, 94, 80, 50, and 35 for 1/3, 1/2, 1, 3 and 9 bars soil moisture tension, respectively. Uptake of P was a linear function of the soil moisture content for a given soil. Thickness of moisture films, diffusion path length, degree of hydration and elongation of the roots appeared to be the factors controlling P uptake in relation to moisture tension. Uptake of P at constant moisture tension on soils differing in texture and soluble P level was a linear function of solution P concentration, but the range of concentration investigated was small. Phosphorus uptake from a soilroot system differs appreciably from a solution‐root system, which suggests that the soil introduces a limiting factor in rate of P uptake.
The Use of Spheres to Measure Lift and Drag on Wind‐Eroded Soil Grains
Authors: Chepil W. S. 
Published: July 2010

AbstractExperiments were conducted to determine the relative magnitude of lift and drag on small spheres, similar to soil grains, at different heights in a fluid boundary surface and to determine if these forces are related to movement of soil grains in saltation.Lift on the average was about 75% that of drag when a sphere was at zero height. Lift decreased with height and virtually ceased a short distance above ground. The greater the ground roughness and drag velocity, and therefore the steeper the velocity gradient, the higher lift extended. It is concluded that lift is caused by a steep wind velocity gradient near the ground.Drag on the spheres was generally much greater than lift. Drag increased directly with an increase in wind velocity and was apparently due to direct pressure of the wind against the sphere.It is evident from these experiments that lift alone is too small to cause the saltating grains to rise, as they do, essentially vertically. The predominantly vertical rise apparently is the way the saltating grains rebound from the ground.
Determination of Arsenic in Flue‐Cured Tobacco and in Soils
Authors: Small H. G. , McCants C. B. 
Published: July 2010

AbstractProcedures are described for the semimicro analysis for arsenic in flue‐cured tobacco and in soils. The plant material is digested with a mixture of nitric, sulfuric and perchloric acids and the soil with sulfuric and perchloric acids. Arsenic is distilled directly from the digestion flask, absorbed in an iodine solution and determined colorimetrically by the molybdenum‐blue method.The data show that good recovery of arsenic and reproducibility of results were obtained with the described procedures. The acid digestion method for plant material gave results which were comparable to those obtained by oxidation in an oxygen bomb. The evidence from soils indicates that the digestion and distillation procedure employed removed essentially all of the arsenic.
Clay Skin Genesis in Wisconsin Soils
Authors: Buol S. W. , Hole F. D. 
Published: July 2010

AbstractClay skins separated from the B3 horizon of the “Ockley‐like” silt loam, a Gray‐Brown Podzolic soil, were further analyzed and found to contain 186% as much total phosphorus and 177% as much total manganese as the bulk of the same horizon. More than 200 thin sections were made of samples from a variety of Wisconsin soils, including soils of the Podzol, Gray‐Brown Podzolic, Brunizem and Humic‐Gley great soil groups. A study of volume of clay skins, as determined from microscopic views of thin sections, and soluble salt concentration revealed that in the “Ockley‐like” profile maxima of both occurred in the C1 horizon. By alternately leaching with percolate from a leaching column and drying with a water aspirator, artificial clay skins were produced in “unweathered” loess material. From observations made during this study a definition of the term “clay skin” is proposed and it is concluded that clay skins in Wisconsin soils are formed by the percolation of dilute clay suspension, from which clay is deposited at or below the bottom of the solum as percolation ceases and the larger pores are emptied of water.
The Apparent Swelling Behavior of Some Moderately Dispersed Bentonites
Authors: Rollins Myron B. , Hallam Merrill J. , Myers Victor I. 
Published: July 2010

AbstractA study was conducted to measure the swelling rate of various dispersed bentonites. The purpose was to characterize the role of continued swelling of clay micelles in the sealing of irrigation conveyance channels with seepage‐transported bentonite.Centrifugal forces were used to separate hydrated, expanded bentonite micelles from the free water of a dispersed system. Eight bentonite samples were successfully settled and their hydrated volumes measured. Seven of the eight bentonites measured continued to swell with time, although most of the samples reached a large percentage of their total expansion within 15 minutes after dispersion. Some bentonites showed a substantial amount of continued swelling. The time required to reach maximum volume for the seven bentonites varied from 3 to 21 days.The results suggest that the phenomenon of continued swelling of bentonites may have a role in the sealing of irrigation conveyance channels with seepage‐transported bentonite.
Root Growth and Diffusion Rates as Functions of Oxygen Concentration
Authors: Stolzy L. H. , Letey J. , Szuszkiewicz T. E. , Lunt O. R. 
Published: July 2010

AbstractThis paper deals with two aspects of soil‐oxygen‐plant relationships: (1) the effect of O2 concentration on O2 diffusion rates, and (2) the O2 diffusion rate in relation to root growth of established plants. The study was designed to minimize the effects of CO2 on root growth during the experiment while studying the effects of oxygen supply and root growth.An average O2 concentration of 0.7% above the soil surface virtually stopped root growth while only a few new roots were initiated at the 2% level. Depth of rooting and the O2 diffusion rate associated with this depth were proportional to the concentration of O2 at the soil surface. Root initiation was reduced or stopped when oxygen diffusion rates in the soil were in the range of 18 to 23 × 10‐8 g. cm.‐2 min.‐1. Diffusion rates above 23 × 10‐8 g. cm.‐2 min.‐1 permitted relatively good root growth.
Some Physical, Chemical, and Mineralogical Properties of Compacted and Adjacent Soil Layers in Coarse‐Textured Soils
Authors: Milford M. H. , Kunze G. W. , Bloodworth M. E. 
Published: July 2010

AbstractSome physical, chemical, and mineralogical properties of compacted and adjacent soil layers, which were selected from cultivated and virgin Willacy fine sandy loam soils in the lower Rio Grande Valley of Texas, were studied to attain a better understanding of the compacted zone and its development. Hydraulic conductivity measurements and field studies substantiated the presence of a hardpan layer, which was first encountered at a depth of 3½ to 7 inches and ranged to a depth of 7½ to 12 inches, at each of the five sites sampled. Clay content increased with depth, while sand content decreased. The fine (0.25 to 0.1 mm.) and very fine sand (0.1 to 0.05 mm.) fractions, for all samples, comprised at least 95% of the total sand and more than 60% of the total soil. Soil reaction (pH), organic matter content, cation‐exchange capacity, exchangeable cations, and extractable silica, aluminum, and iron were determined. Extractable cementing materials were not found in important quantities in any of the layers. Mineralogical analyses of the samples showed that quartz and lesser amounts of feldspar composed the sand and silt fractions, while illite and poorly ordered, weathered micaceous materials dominated the clay fraction. No pronounced differences in the chemical and mineralogical properties of the hardpan layers as compared to the layers above and below the hardpan were found.
Experimental Consideration of Diffusion Analysis in Unsaturated Flow Problems
Authors: Nielsen D. R. , Biggar J. W. , Davidson J. M. 
Published: July 2010

AbstractAn experimental investigation of the applicability of the diffusion equation to soil water movement is reported using soils and sandstone with water and oil. The fluids were allowed to enter at different negative pressures into air‐dry horizontal columns of several lengths. The equation predicted the water movement when the entry pressure was −2 millibars. The inability of the equation to predict water movement for greater negative pressures is discussed.