bluuebunny/crossref_metadata_2025 huggingface dataset:
Lack of Evidence for ZnSiO3 in Soils
Authors: Norvell W. A. , Lindsay W. L.
Published: July 2010

The solubility constant for ZnSiO3 reported in the literature is based on invalid thermodynamic data. The agreement between Zn2+ concentrations in some soils and the invalid solubility constant for ZnSiO3 is coincidental. The presence of this compound in soils is very unlikely.
Analysis of Radial, Steady‐State Solution, and Solute Flow
Authors: Whisler Frank D. , Klute Arnold , Millington Richard J.
Published: July 2010

Radial, steady‐state solution and solute flow to a root can be described as flow in a hollow cylinder. The analysis was broken into two parts: the solution flow and solute flow. The equation for the solution flow was solved analytically to obtain the soil solution tension distribution subject to fixed tensions at the inner and outer boundaries. From the tension distribution, the solution content distribution and solution flux were derived. The solution flux approaches a finite limit as the tension across the cylinder increases. The equation of flow for the solute was solved seminumerically, subject to fixed inner and outer concentration boundary conditions. The solute diffusion coefficient was assumed to be dependent upon the solution content. The convective part of the solute flow equation was dependent upon the solution flux. For most cases a good approximation would be the use of a constant solute diffusion coefficient, only dependent upon a mean solution content. As the solution flux increased, the solute concentration gradient increased at the root for both plant uptake or salt sieving of the solute.
Predicting Moisture Distributions in Rewetted Soils
Authors: Staple W. J.
Published: July 2010

Computed and measured soil moisture distributions were compared during second and third cycles of infiltration and redistribution. In order to obtain acceptable agreement, the hydraulic conductivity had to be reduced to about one‐half of the value used in the first cycle for freshly packed soil. Two methods were adopted in obtaining adequate conductivity data. One method was to correct the conductivity by trial and error. The other was to measure the conductivity of the soil after it had been carried through an initial wetting and drying cycle.

Hysteretic effects on rewetting were minimized by adding sufficient water to the partially dried soil to bring it back to its initial wetted condition. The independent domain theory was found satisfactory for providing wetting tension data during the brief infiltration period.

Modified tension scanning curves for drying were used in second‐cycle computations for clay soil but the original curves for freshly packed columns were used for sand. Changes in scanning curves due to consolidation during the first drying cycle were not studied in detail. Successive rewetting was predicted satisfactorily only after the boundary condition for infiltration was changed from ponded water at the surface to an applied flux which was below the maximum infiltration rate.
Hydraulic Conductivity of an Isotropically Compressed Soil
Authors: Waldron L. J. , McMurdie J. L. , Vomocil J. A.
Published: July 2010

Hydraulic conductivities (K) of disturbed samples of Yolo loam were measured under isotropic confining pressures of from 0.1 to 3.2 kgm/cm2 in a triaxial test cell. Solutions of 1, 10, and 100 meq/liter of NaCl or CaCl2 produced marked differences in K, slight effects on compressibility, and no effect on soil dispersibility. The Kozeny‐Carman equation showed the same pattern of failure reported for clays and soils compressed anisotropically, i.e., K declined much more with decreasing porosity than predicted. Hypothetical K versus depth profiles calculated from K versus confining pressure data support a hypothesis that the K decreases with depth reported in texturally homogeneous soils may be attributable to overburden pressure.
Selenium Concentrations in Phosphorus Fertilizer Materials and Associated Uptake by Plants
Authors: Robbins C. W. , Carter D. L.
Published: July 2010

The Se concentration of seven Florida Land Pebble deposit phosphate rocks ranged from 0.7–7.0 ppm. The range was 1.4–178 ppm Se in seven samples from the western phosphate field. The Meade Peak phosphatic shale member of the Phosphoria formation contains more Se than rock from other phosphatic formations. Normal and concentrated superphosphates made from phosphatic rocks containing 100 ppm Se can be expected to contain about 60 and 40 ppm Se, respectively. Laboratory‐prepared concentrated superphosphate containing 23 ppm Se applied to an alkaline soil that normally produced alfalfa (Medicago sativa L.) low in Se at a rate of 156 ppm P increased Se concentration in alfalfa above the minimal requirements to protect livestock from white muscle disease. Concentrated superphosphate and single superphosphate prepared from phosphate rock containing 178 ppm Se and applied at a rate of 80 ppm P increased the Se concentration in alfalfa compared to the same amount of P applied as Se free concentrated superphosphate. Normal phosphate fertilizer practices can provide required Se for livestock provided the fertilizer is prepared from phosphate rock containing sufficient Se.
Use of the Leco Automatic 70‐Second Carbon Analyzer for Total Carbon Analysis of Soils
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

Studies with surface and subsurface soils containing 0.3–34% organic carbon and with carbonate standards showed that the Leco automatic 70‐second carbon analyzer is satisfactory for determination of total carbon in soils. The Leco procedure evaluated involved high‐temperature combustion of soil with a high‐frequency induction furnace in a stream of purified oxygen and measurement of the carbon dioxide evolved by a thermal‐conductivity technique providing automatic readout of the carbon content of the sample.

With all soils analyzed, the results of total carbon analysis by the Leco analyzer agreed closely with, and were as precise as, those obtained by the wet‐combustion method of Allison. Total carbon analysis of soils by the Leco analyzer is very simple and rapid, and a single operator can easily perform more than 150 analyses in a normal working day.
Effects of Lime upon Soil and Plant Manganese Levels in an Acid Soil
Authors: White R. P.
Published: July 2010

‘Charlottetown 80’ and ‘Herta’ barley (Hordeum vulgare L.), ‘Charlevoix Red Kidney’ and ‘French Horticultural Bush’ beans (Phaseolus vulgaris, L.), and ‘Century’ peas (Pisum sativum L.) were planted in an acidic podzol soil (pH 4.7) after application of dolomitic limestoen at rates of 0, 375, 750, and 1,500 ppm. Soil and tissue samples obtained at bloom (beans and peas) and at heading and maturity (barley) indicated that soil Mn extracted with H2O and with neutral 1N NH4OAc as well as plant tissue Mn levels were markedly reduced by liming. Soil Mn levels were well correlated with pH and tissue Mn levels. Manganese toxicity symptoms were observed at tissue Mn levels of approximately 1,000 ppm in beans, 550 ppm in peans, and 200 ppm in barley.

Charlevoix Red Kidney beans appeared a good indicator plant for Mn toxicity studies.
Influence of Rainfall Energy on Soil Loss and Infiltration Rates: II. Effect of Clod Size Distribution
Authors: Moldenhauer W. C.
Published: July 2010

Various clod size distributions were subjected to drop impact from a water drop applicator that delivered only 5‐mm drops. Clod beds were exposed to drops in 30‐ by 45‐cm pans. Point of “failure” of the clod bed was the accumulated energy when runoff began. Increasing the maximum clod size from 20 to 40 mm did not delay the time for runoff to begin on four silt loam to silty clay textured Iowa soil samples taken from continuous‐corn plots. Removing the < 2‐mm clods from the < 40‐mm sample had little effect on the time to runoff on continuous‐corn soils, but did increase the time to initial runoff on the silt loam soil from meadow. Removing the fraction < 8 mm from the < 40‐mm sample significantly increased the rainfall energy required to initiate runoff in all instances tested. Removing the fraction < 30 mm from the < 40‐mm sample nearly doubled the energy to initial runoff. However, clod beds of this 30‐ to 40‐mm size range from continuous corn did not withstand 0.18 joules cm‐2 of rainfall energy—the energy that occurs in western Iowa during the critical erosion period. Clod beds of the 30‐ to 40‐mm size range from continuous meadow, in contrast to clod beds from corn land, did withstand 0.18 joules cm‐2 of rainfall energy.
Arsenic Sorption by Soils
Authors: Jacobs L. W. , Syers J. K. , Keeney D. R.
Published: July 2010

Retention of As against extraction by NH4OAc and Bray P‐1 reagents from Wisconsin soils equilibrated with As (0, 80, and 320 µg As/g added as Na2HAsO4) increased as the sesquioxide content increased. Similarly, the amount of As sorbed from solution increased as the free Fe2O3 content of the soils increased. Removal of amorphous Fe and Al components by treatment with oxalate eliminated or appreciably reduced the As sorption capacity of the soil. Amorphous Fe and Al components preferentially sorbed added As, as evidenced by the quantitative removal of added As from equilibrated soils by a single oxalate extraction and the essentially complete recovery of added As by NH4F and NaOH reagents during chemical fractionation. Because As released during extraction with NH4F is sorbed by soil components during the same extraction, NH4F‐As is underestimated unless a correction for resorption is made.
Occurrence of Amino Sugars in Extracellular Polysaccharides of the Genus Rhizobium and Some Observations Regarding Their Distribution in Somatic Components
Authors: Stevenson F. J. , Clapp C. E. , Molina J. A. E.
Published: July 2010

Chromatographic analysis of amino sugars in hydrolysates of some extracellular polysaccharide preparations from the genus Rhizobium revealed the occurrence of at least six amino sugars, of which three (glucosamine, galactosamine, and muramic acid) were positively identified. Not all of the amino sugars could be accounted for as structural components. Analysis of phenol‐extractable polysaccharides and proteins from intact cells showed that the various species of Rhizobium differed greatly in the kinds and amounts of amino sugars they synthesized.
Selective Dissolution Effects on Cation‐Exchange Capacity and Specific Surface of Some Tropical Soil Clays
Authors: Reneau R. B. , Fiskell J. G. A.
Published: July 2010

Soil clays from eastern Panama and Wyoming bentonite changed in CEC and specific surface after sequential selective dissolution treatments. Dithionite‐citrate treatment of the clays resulted in a small increase in CEC at both pH 4.8 and 8.2 and a decrease in ethylene glycol retention. Free Fe2O3 ranged from 2% to 9% of the clay weight and substantial Al2O3 and SiO2 were also removed. Further treatment with hot 0.5N NaOH for 2 minutes again followed by citrate‐dithionite resulted in 20% to 40% loss in clay weight as SiO2 and lesser amounts of Al2O3 and Fe2O3. This treatment resulted in an increase of 7 meq in CEC at both pH ranges of soil clays and 20 meq for the bentonite. This was attributed to removal of interlayer material blocking exchange sites but there was a mean decrease in specific surface after this treatment. Clays treated with acid NH4F‐NH4Cl reagent for 10 minutes decreased sharply in specific surface and loss in clay weight was from 9% to 17% with SiO2 > Al2O3 > Fe2O3. After Na saturation and careful washing, Na replacement by 1N NH4OAc at pH 4.8 also removed high amounts of F and Al making CEC estimation impractical because NaF and/or Na3AlF6 was occluded in the process of Na saturation.
Effect of Gibberellic Acid in Fertilizer Packets on Growth of Cottonwood and Silver Maple
Authors: Rasson F. L. , Attoe O. J. , Boyle J. R.
Published: July 2010

Addition of fertilizer packets containing 0.5% or 2% gibberellic acid to potted soil significantly increased height growth rates of cottonwood (Populus deltoides Marsh.) cuttings over that for packeted fertilizer alone. Plant weight increases were significantly higher for 0.5% gibberellic acid in the two‐packet treatment but not in the one‐packet treatment. Similar treatments with gibberellic acid in the field did not increase the height or diameter growth rates of cottonwood cuttings, and caused a significant decrease in growth rate of silver maple (Acer saccharinum L.) plantings for the two‐packet treatment with 0.5% gibberellic acid. The latter treatment reduced survival of this species to 60% from 95% for fertilizer alone.
Wind Erosion Equation: Computer Solution and Application
Authors: Skidmore E. L. , Fisher P. S. , Woodruff N. P.
Published: July 2010

A wind‐erosion equation was programmed for computer solution. The relationships among variables are evaluated by the computer, and the general functional relationship between soil loss and independent variables, E = f(I', C', K', L', V), is solved stepwise to give potential average annual soil loss, E, in tons per acre per annum for specified conditions of erodibility, I'; roughness, K'; climatic factor, C'; equivalent field length, L'; and equivalent vegetative cover, V. The computer also can solve the equation to determine field conditions necessary to reduce potential erosion to a tolerable amount and can compare the effectiveness of various combinations of erosioncontrol treatments.
Nitric Oxide Volatilization from a Calcareous Soil and Model Aqueous Solutions
Authors: Steen W. C. , Stojanovic B. J.
Published: July 2010

Nitric oxide (NO) was volatilized from a laboratory aerobically incubated West Point loam (amended with different rates of urea or ammonium sulfate nitrogen) and from aqueous solutions containing ammonium and nitrate ions. Oxide loss from the soil was dependent upon the source and rate of nitrogen applied. Urea‐treated soil samples fertilized with 50, 100, 200, and 300 ppm of N lost 8.9, 17.8, 26.6, and 35.5 kg N/ha, respectively. Similar NO losses were observed from ammonium sulfate treatments, although these were substantially smaller. Also, losses of NO from sterile soil samples supplemented with ammonium and nitrite in concentrations equivalent to those occurring in the nonsterile soil at the peak of oxide volatilization were comparable to those of the nonsterile soil. Aqueous solutions containing nitrite and ammonium or urea nitrogen, with or without ferrous iron, humic acid, or lignin, which were buffered from pH 6.5 to pH 8.0, volatilized appreciable quantities of NO over the entire pH range tested. A decrease in methyl content of organic matter suggests that methyl nitrite may have been volatilized.
Nitrogen Fixation by Azotobacter paspali in Association with Bahiagrass (Paspalum notatum)
Authors: Kass Donald L. , Drosdoff Matthew , Alexander Martin
Published: July 2010

Establishment of Azotobacter paspali in the rhizosphere of Paspalum notatum grown in sand was consistently successful only with tetraploid varieties of the grass when glucose was added at the time of inoculation. Increases in the nitrogen content of the roots and in the total nitrogen content of the sandplant system were associated with successful Azotobacter colonization. These increases were significant at p < 0.05. There was no evidence for improved growth or for nitrogen gains in the above‐ground portions of the plants resulting from A. paspali establishment.

Soils containing tetraploid P. notatum and A. paspali showed considerable nitrogen fixation, as measured by acetylene reduction. The nitrogen gains appeared to be a consequence of growth of photosynthetic microorganisms, since all fixation ceased when soils were incubated in the dark.
Canfield Silt Loam, a Fragiudalf: II. Micromorphology, Physical, and Chemical Properties
Authors: Miller F. P. , Wilding L. P. , Holowaychuk N.
Published: July 2010

Although cutans comprise less than 1 to 2% of the total soil volume, they impart a disproportionately large influence to the soil as a medium for plant growth. This impact is maximized in the Canfield fragipan where rooting volumes are almost exclusively restricted to polygonal ped interfaces. Sampling these morphological units of fragipan horizons revealed twice as much total clay and three times as much < 0.2µ clay in the cutan segments of the horizon as in the matrix material or bulk horizon sample. Quantities of exchangeable cations were roughly proportional to the clay content, but the exchangeable K and Sr were nearly four and five times more concentrated, respectively, in the cutanic material, suggesting a possible mineralogical difference between the cutan and matrix or bulk mineralogy. X‐ray analysis indicated that the total clay fraction of the cutan material contained a greater proportion of nonexpandable and expandable 14Å and 17Å minerals, as well as interstratified components, when compared to the matrix and bulk clay fraction. Thin section analysis in conjunction with textural analysis and profile descriptions verified the presence of an argillic horizon above the fragipan and revealed the laminar morphology of the polygonal interface. From these data and observations the genetic sequence of the Canfield series is suggested.
The Mobility of Phosphorus, Potassium, and Calcium in a Forest Soil
Authors: Riekerk Hans
Published: July 2010

A study was made to evaluate the movement of nutrient elements in rainwater percolating through a well‐drained Douglas‐fir (Pseudotsuga menziesii (Mirb.) Franco) forest soil. Radiotracers of phosphorus, potassium, and calcium, mixed with stable elements, were applied to the forest floor simulating rainwash input. Leachates from tension lysimeters were collected periodically and analyzed for nutrient and tracer contents. Trees and soil were sampled and analyzed at the end of the experimental period. The data showed large coefficients of variation typical of biological materials. Twenty percent of the labeled phosphorus leached through the forest floor during the year, representing 10% of the total phosphorus movement with rain water. Similarly, 8% of labeled potassium, representing 27% of leached potassium, and 2% of labeled calcium, representing 5% of leached calcium, moved annually with rain water through the forest floor. Comparable leaching values through the top 20 cm of mineral soil were a thousand times less, but with most of calcium and least of phosphorus released. These data were related to forest soil contents and indicated the elemental mobility to be dependent on the physico‐chemical properties of the forest soil, as well as the ionic properties and biological functions of the nutrient elements.
Phosphorus Diffusion in Soils: I. The Effect of Applied P, Clay Content, and Water Content
Authors: Mahtab Samuel K. , Godfrey Curtis L. , Swoboda Allen R. , Thomas Grant W.
Published: July 2010

Self‐diffusion coefficients of 32P (D) were measured in four soils: Miller clay, Norwood loam, and two textural intergrades of these two soils. Clay percentages of the soils were: Norwood, 12.5; Intergrade I, 25.0; Intergrade II, 36.0; and Miller, 59.0. The P rates used were 0, 25, 50, and 100 ppm. The moisture levels were 35, 60, and 100% of the water content between ⅓ and 15 bars tension. The D values averaged over all clay and P levels, increased from 10.25 × 10‐10 to 27.76 × 10‐10 cm2/sec as the water content increased from 35 to 100% of the available moisture. The average D value increased from 5.05 × 10‐10 for the Norwood to 26.59 × 10‐10 cm2/sec for the Miller soil. Likewise, D values increased with increasing rates of added P for all soils. The data indicated reduction in available water has less effect on diffusion rates of P in clay soils than in the lighter‐textured soils. It follows that in order to maintain a given rate of diffusion in a soil, as water content decreases, the amount of added P must be increased.
Introduction to Symposium—The Soil Solution
Authors: Pearson Robert W.
Published: July 2010

Evidence is presented for validity of the concept of soil solution composition as a useful reflection of soil chemical environment that can be related to plant‐root growth. Analysis of soil extracts does not give the same information. Samples of the soil solution can be obtained by displacement at any desired moisture level.
The Role of Sparingly Soluble Solids and Cation Exchange Reactions in Controlling Conditions in Soil Solutions
Authors: Turner R. C. , Singh S. Shah
Published: July 2010

The application of the principle of solubility products of relatively insoluble solids and exchange reactions to soil problems are discussed. The examples used concern the solubility products of hydroxyaluminum solids, whether thermodynamically stable or metastable, and exchange reactions with clay surfaces involving aluminum and calcium ions.
Effect of Added Salts on Nitrogen Mineralization in Three California Soils
Authors: Broadbent F. E. , Nakashima T.
Published: July 2010

The effect of ammonium sulfate, ammonium chloride, potassium chloride, calcium chloride, aluminum chloride, and copper sulfate added in amounts corresponding to 0.2, 2, and 20 atm concentration on mineralization of soil nitrogen in three soils was measured over a 30‐day period. Significant increases were produced by the ammonium salts which were labeled with 15N to allow distinction between added and soil nitrogen. In Aiken clay loam nitrogen mineralization was also increased by solutions of potassium chloride, calcium chloride, and aluminum chloride, but in Altamont clay loam and Mormon clay increases were not consistent. Copper sulfate depressed nitrogen mineralization in all soils. It was found that the quantity of organic nitrogen brought into solution was related to the concentration of the salt solution.
The Occurrence of 2‐Methoxy‐1,4‐Naphthoquinone in Caribbean Vertisols
Authors: Lambert E. N. , Seaforth C. E. , Ahmad N.
Published: July 2010

An orange colored pigment identified as 2‐methoxy‐1,4‐naphthoquinone was separated and identified from the dark colored 0 to 15‐cm layer of Caribbean Vertisols. Extraction of the pigment was carried out by shaking the soil (> 2 mm) in CHCl3 (1:2) and decanting the supernatant liquid from which the pigment was purified by column chromatography and crystallization from ethanol. Eight kilograms of soil yielded 69 mg of the pigment. Identification of the pigment was determined using a combination of techniques including solubility tests, elemental analyses, melting point, ultraviolet, infrared, NMR, and mass spectroscopy. To the authors' knowledge, the isolation described herein is the first for a nonchlorophyllic pigment occurring in a chemically uncombined form in a tropical soil.
Influence of Simulated Fall and Spring Conditions on the Soil System: II. Effect on Soil Nitrogen
Authors: Campbell C. A. , Biederbeck V. O. , Warder F. G.
Published: July 2010

Stored and fresh Wood Mountain loam samples were wetted to 20% moisture using either water, Ca(NO3)2, or (NH4)2SO4 solutions. Half of the samples were sterilized with ethylene oxide. Fall conditions were imposed by incubating samples at diurual temperatures of 14 to 3C and early spring conditions by slow freezing to −23C followed by incubation at 14 to 3C or 8.5C. Exchangeable NH4‐N, NO3‐N, and microbial counts were determined at appropriate intervals.

In the unamended and NO3‐amended soils, freezing followed by 16 days incubation at 14 to 3C had a bactericidal effect and resulted in a much lower rate of nitrification than freezing followed by incubation at 8.5C. Where NH4 had been added the bactericidal effect was not as great and there was no difference in nitrification between the two incubation temperatures.

Incubation at low temperatures impeded nitrification more than ammonification which resulted in an initial buildup of exchangeable NH4.

Ethylene oxide was an effective soil sterilant but caused a small increase in the exchangeable NH4.

Freezing followed by incubation at low temperatures increased the exchangeable NH4 in sterile soils but did not affect the NO3 content. There was evidence of an interaction between the length of soil storage and the various treatments (viz, freezing, sterilization, etc.).
Air Permeability of Undisturbed Soil: Variability and Measurement with an Asphalt Paving Meter
Authors: Fritton D. D.
Published: July 2010

An asphalt paving meter which allows convenient and rapid measurement of air permeability was used in undisturbed soil. Permeability differences due to location in a field were significant, but since the absolute values contain an unknown and variable combination of vertical and horizontal permeability, the measurements are likely to be useful only under very special circumstances.
Boron Adsorption Characteristics of Selected Amorphous Soils From Mexico and Hawaii
Authors: Bingham F. T. , Page A. L. , Coleman N. T. , Flach K.
Published: July 2010

Boron adsorption by Mexican and Hawaiian soils derived from volcanic ash deposits as influenced by solution phase concentration, reaction time, suspension pH, temperature, percent amorphous Al2O3 and SiO2, and free Fe2O3 content was studied. The adsorption was satisfactorily described by the Langmuir adsorption equation. Adsorption maxima were considerably greater than those observed for soils derived from other kinds of parent materials. In the range from 10 to 40C increases in temperature affected boron adsorption slightly. Maximum adsorption occurred between pH 8 and 9, suggesting that these soils have a greater affinity for B(OH)‐4‐B than for B(OH)3‐B. Boron adsorption by both the Mexican and Hawaiian soils was significantly correlated with amorphous SiO2 plus Al2O3 and amorphous Al2O3. However, higher correlation coefficients were obtained between boron adsorption and percent amorphous Al2O3. No significant correlations were found between boron adsorption and amorphous SiO2, and free F2O3 content.
Pesticide Adsorption Measurement by Flow Equilibration and Subsequent Displacement
Authors: Green R. E. , Corey J. C.
Published: July 2010

Adsorption of pesticides from solution was measured by continuous‐flow equilibration and subsequent displacement from the soil by organic solvents. This new method and the conventional batch‐equilibration method gave similar results for adsorption of diuron and atrazine on three surface soils. The flow method gave superior precision to the batch method on the subsoils studied. The new procedure is well adapted to studies of adsorption reversibility and also has the advantage of limited destruction of soil aggregates during equilibration.
Soil Lipids under Various Crops
Authors: Wang Thomas S. C. , Hwang Pau‐tsung , Chen Chung‐yi
Published: July 2010

Two parent materials of soils; namely tertiary sandstone and mudstone, as well as several soils planted with various crops were investigated by means of thin‐layer chromatography and gas chromatography for their lipid content. The total free fatty acids were found in greater quantity and variety than the fatty acids of the triglycerides of most of the materials studied. In addition to small amounts of many acids having odd numbers of C‐atoms, the predominant free fatty acids were myristic, palmitic, palmitoleic, stearic, oleic, and arachidic acids. The sugarcane (Saccharum officinarum L.) soils invariably showed some large characteristic peaks of unknown compounds on the gas chromatograms, whereas the soils planted with paddy rice (Oryza sativa L.), banana (Musa paradisiaca), or pineapple (Ananas comosus) did not show any characteristic component. In all of the soils, there were many unknown peaks on the chromatograms of the methyl esters of both the free fatty acids and the fatty acids of the triglycerides. They could be iso acids, ante‐iso acids, and branched fatty acids derived from micro‐organisms. Paraffinic hydrocarbons frequently appeared. In some soils, an unknown nonpolar compound and dioctyl phthalate were found. The latter might be also of microbial origin. The sandstone and mudstone contain fewer lipids. The relationship between the composition of the lipids and the characteristics of the soils is not obvious.
Some Effects of Aggregate Structure Heterogeneity on Root Growth
Authors: Voorhees W. B. , Amemiya Min , Allmaras R. R. , Larson W. E.
Published: July 2010

Roots of barley (Hordeum vulgare) seedlings were allowed to grow into soil aggregates about 1 cm in diameter. The aggregates were formed to have densities ranging from 1.4 to 1.8 g cm‐3. The resulting physically different internal structures were used to vary the extent of root proliferation within the aggregate. Aggregates of different densities were mixed so that the roots had equal opportunity to grow into the various physical types of aggregates. Root growth into a given aggregate type was ascertained by tagging certain aggregates with 32P.

Roots penetrated agregates having dry densities of 1.4 g cm‐3 but were restricted to the periphery of aggregates having a dry density of 1.8 g cm‐3. Root growth within a given aggregate was also affected by the soil strength and pore size distribution within adjacent aggregates. Roots growing in beds of aggregates of uniform density were qualitatively, as well as quantitatively, different from roots growing in beds of aggregates with more than one density. Although not measured directly, the extent of root hair development and the soil volume explored by a given root segment in various physical environments were likely responsible for this difference in root characteristics. The relationship between these data and field observations is given.
Determination of Trace Elements in Soils and Clay Minerals by Resonance Neutron Activation Analysis
Authors: Murrmann R. P. , Winters R. W. , Martin T. G.
Published: July 2010

Bentonites 23 and 25, Umiat bentonite, Koalinite 7, Halloysite 29, Illite 35, and Fairbanks, Barrow, and Suffield silts were irradiated with resonance neutrons by exposure of cadmium shielded samples in a reactor for 40 hours in order to identify the elements having long half‐life nuclides which could be quantitatively determined using nondestructive neutron activation analysis. By examination of the gamma‐ray spectra obtained using a high resolution Ge(Li) detector, it was possible to identify Fe, Ti, Zn, Ni, Co, Cr, Sr, Ba, Cs, La, Eu, Tb, Hf, Ta, Th, and U in most of the samples. Although quantitative results were obtained only for Fe, Ti, Zn, Ni, Co, and Cr, this method appears suitable for nondestructive quantitative analysis of all the elements identified.
The Hydraulic Conductivity‐Water Content Relationship During Nonsteady Flow Through a Sand Column
Authors: Rogers J. S. , Klute A.
Published: July 2010

Water contents and hydraulic heads were measured for three rates of draining and rewetting a vertical column of sand. Fluxes of water determined from the water content data and hydraulic gradients determined from the hydraulic head data were used in Darcy's Law to determine hydraulic conductivity. The hydraulic conductivity was a single valued function of the water content exhibiting no hysteresis. There was no relationship between hydraulic conductivity and the rate of change of water content although a rate dependent water content‐pressure head relationship was present in the data.
Interpretation of Curves Describing Soil Potassium Exchange
Authors: Smith S. J. , Liu M. , Clark L. J. , Scott A. D.
Published: July 2010

Curves describing the release of K from soil samples in NaTPB solutions depict a linear relationship between the amount of K replaced and the logarithm of the extraction period. Such curves are quite different from the diffusion‐controlled curves observed with mica particles and have yet to be explained. Reports of a similar relationship being observed with soil organic N release that also obeyed a second‐order reaction led to an unsuccessful application of second‐order kinetics to the release of K from 16 soils. On the other hand, linear K‐releases versus log t curves were obtained by combining K‐release curves for mica particles of different size and by placing mixtures of mica particles in the same NaTPB solution. Therefore, a soil was fractionated, and the K‐release curves for the individual size‐fractions were determined. The curves for the soil fractions were nonlinear and more like mica curves, whereas various combinations of these curves yielded linear K‐release versus log t relationships like those observed with soils. Thus, the curves for soil K‐release merely represent the combined effects of various particle sizes in the soil and not a distinctive mode of release.
Potassium Removed from Some Southern Brazilian Soils by Exhaustive Cropping and Chemical Extraction Methods
Authors: Oliveira V. , Ludwick A. E. , Beatty M. T.
Published: July 2010

Soils from the orders Alfisol, Inceptisol, Mollisol, Ultisol, and Oxisol contained exchangeable K (neutral 1N NH4OAc) and boiling 1N HNO3 extractable K varying from 31 to 358 ppm and 62 to 652 ppm, respectively. Total K varied from 1,780 to 14,200 ppm. Quantities absorbed from each soil by 7 cuttings of perennial ryegrass (Lolium perenne) in the greenhouse ranged up to 13 times that of exchangeable K and up to 5 times that of HNO3‐extractable K. Total plant uptake represented 3.5 to 29.7% of total soil K. In no soil did K become limiting in the first four cuttings. However, except for the Mollisols, uptake decreased abruptly in the later cuttings, indicating very little “slowly” available K. Even though exchangeable K and K removed by strong acids were highly correlated with plant uptake (r = 0.744** to 0.881**), all extractants greatly underestimated actual plant‐available K under intensive cropping. Total soil K did not significantly correlate with plant uptake (r = 0.211).
Differentiation of Sr‐Ca Supply Mechanisms to Roots Growing in Soil, Clay, and Exchange Resin Cultures
Authors: Bole J. B. , Barber S. A.
Published: July 2010

The ratio of Sr/Ca taken up by soybean roots growing in soil, clay, and exchange resin media was used to evaluate the mechanisms supplying these cations to the root surface. When mass‐flow supplied more than uptake, the Sr/Ca ratio of uptake was similar to the Sr/Ca ratio in the soil solution. This is the ratio for the mass‐flow supply mechanism. When mass‐flow supplied a minor proportion of uptake, the Sr/Ca ratio of uptake corresponded to the Sr/Ca ratio of the exchange cations rather than the solution cations. This indicated that the supply by contact of the media with the root and by diffusion was in the ratio of Sr/Ca found on the exchange sites.
Clay Mineralogy of Certain Rice Soils in Southern Taiwan
Authors: Juo A. S. R. , Chi C. L. , Wu M. H.
Published: July 2010

Clay minerals present in fine‐textured rice soils in southern Taiwan were identified by X‐ray diffraction and chemical analyses. Dioctahedral mica with high potassium content is the predominant mineral in the clay fraction. These soil clays also contain considerable amounts of iron‐rich chlorite, smectite, and vermiculite.
Modification of Certain Soils by Calcium Hydroxide Stabilization
Authors: Pettry D. E. , Rich C. I.
Published: July 2010

Physical changes induced by prolonged Ca(OH)2‐treatment were determined for natural peds from specific horizons of Beaumont, Hiwassee, Houston Black, Katy, and Nacogdoches soils. Confined swelling pressures, liquid limits, and plasticity indexes decreased substantially for soil peds treated with 5% Ca(OH)2 for 60 days in a humid atmosphere. Calcium carbonate appeared to be the dominant soil—Ca(OH)2 reaction product.

Treatment with 5% Ca(OH)2 (weight basis) drastically reduced the intensity of the characteristic X‐ray reflections of phyllosilicates. However, washing the treated clays with 1N HCl restored the intensity of reflections to the approximate original intensity; thus the crystallinity of the phyllosilicates remaining after Ca(OH)2‐treatment remained intact. X‐ray diffraction studies indicated a reduction in interlayer expansion of Casaturated 2:1 expansible layer clay fractions after a 30 min treatment with 5% Ca(OH)2 at 100% relative humidity.

Microscopic examinations of whole soil peds and thin sections of peds treated with Ca(OH)2 for 1 year revealed changes in the soil fabric. Intergranular bridges of reaction products were observed along pressure faces and channels. Interior walls of soil voids were lined with soil‐Ca(OH)2 reaction products suggesting penetration in a liquid form.
Determination of Solid‐Air Surface Tension of Porous Media
Authors: Miyamoto S. , Letey J.
Published: July 2010

The advancing wetting conditions of porous media by various kinds of pure liquids was considered theoretically based on Fowkes' dispersion theory and capillary rise equation. It was then hypothesized that the wettability and repellency under the advancing process can be characterized in terms of the advancing spreading coefficient, and could be predicted from the data of liquid surface tension and of solid‐air surface tension of porous media. Experimental data within the contact angle wetting (0<θa<90°) in soil and sand samples with several organic liquids and water indicated reasonably good agreement to the theory. Based on this agreement new methods—surface tension and liquid drop—were proposed to determine the solid‐air surface tension. These methods were found to be workable for appreciable range of water‐repellent porous media.
Miscible Displacement of Ammonia in Soil; Determining Sorption Isotherms
Authors: Rolston D. E. , Nielsen D. R. , Biggar J. W.
Published: July 2010

Although anhydrous ammonia is used extensively as a common source of nitrogen for crop production, there is probably less known concerning its behavior after application to soils than that of any other nitrogenous fertilizer. Most techniques used in the past for evaluating the sorption characteristics of anhydrous ammonia have utilized steady‐state or so‐called equilibrium conditions without considering a method that allows or accounts for simultaneously‐occurring mass flow, diffusion, and sorption of the ammonia gas. A miscible displacement technique was developed that entails the displacement of the atmosphere from oven‐dry soil columns with ammonia at flow velocities of approximately 100 cm hr‐1.

Transient sorption isotherms calculated from miscible displacement experiments were compared with the measured steady‐state and transient sorption isotherms for both adsorption and desorption. Isotherms relating the amount of sorption S to the relative ammonia density P (or concentration) were of the nonlinear from S = kPn + ko where k, ko, and n were sorption constants different for adsorption and desorption.
Soil Profile Gravel Layers: II. Effect on Growth and Water Use by a Hybrid Forage Sorghum
Authors: Unger Paul W.
Published: July 2010

A hybrid forage sorghum (Sorghum vulgare Pers. × Sorghum vulgare var. sudanense) was planted in field plots having a gravel layer placed on or 5, 15, or 25 cm below the surface, and in check plots. Rapid soil drying delayed seedling emergence about 2 days for the 5‐cm treatment in 1969, and for all except the surface gravel treatment in 1970. In both years, rainfall several days after seeding resulted in good seedling emergence and plant establishment. However, the delayed emergence retarded early growth, and plants were tallest at harvest on the surface gravel plots. Dry‐matter yields of the first crop were highest on the surface gravel plots, but second‐crop (plant regrowth) yields were highest on the check plots each year. Nitrogen deficiency may have reduced yields for the second crop on the surface gravel plots in 1969. Also, the second crop was uniformly irrigated each year, which resulted in more uniform soil water replenishment than that occurring from rainfall. Subsequent water use by the crop was similar on all plots. The subsurface gravel layers interfered with deep‐infiltration of water from rainfall and reduced the utilization of rainfall for crop production on these plots. Trends in water use efficiencies were similar to trends in dry matter production.
Lycopodium Fairy Rings: Effect on Soil Nutrient Release
Authors: Stone E. L. , Thorp Lynne
Published: July 2010

Colonies of four clubmosses, Lycopodium tristachyum, L. complanatum, L. clavatum and L. obscurum, sometimes occur as “fairy rings”—densely stocked annuli that grow outward and die within. Readily soluble N, P, K, and Fe in the surface soil increased sharply at the point where roots first developed along the advancing lycopod rhizomes; maxima occurred near or beyond the zone of greatest biomass and usually levels declined inward. Extractable Mn was either higher or lower within the ring, depending on season of sampling; Ca and Mg were unaffected. These changes are attributed to increased mineralization of organic matter and altered solubility of Fe and Mn oxides. The capacity of the lycopod root‐ or root‐fungus system to exploit reserves unavailable to other plants presumably conveys a competitive advantage and accounts for the abundance of Lycopodium on some low‐fertility soils.
Ammonium Pyrophosphate and Ammonium Orthophosphate as Phosphorus Sources: Effects of Soil Temperature, Placement, and Incubation
Authors: Engelstad O. P. , Allen S. E.
Published: July 2010

Triammonium pyrophosphate [(NH4)3HP2O7] was found to be less effective than monoammonium orthophosphate [NH4H2PO4] when both were freshly added as sources of P for corn (Zea mays L.) grown in cool soil (16C). No difference in effectiveness was found between these sources when freshly applied to warm soil (24C). Incubation prior to planting reduced the effectiveness of both sources, particularly when the soil was warm during the incubation period.
Root Development of Intensively Cultivated Slash Pine
Authors: Schultz Robert P.
Published: July 2010

Root development of 12‐year‐old airlayers and seedlings of Pinus elliottii Engelm. was investigated after 10 years of cultural management on a moderately deep sandy soil. Cultural treatment included a factorial arrangement of irrigation vs. no irrigation, fertilization vs. no fertilization, and disking vs. a legume cover crop. Root surface area and root distribution were estimated from soil core samples, soil pits, and root excavations. Intensive culture significantly altered root surface area and root distribution. Airlayers and trees grown from seed did not differ significantly in total root surface area or in shoot growth. However, all seedlings had well‐defined taproots, while most airlayers had one to three heavy sinkers arching from the root collar to the maximum depth of rooting. Overall, 50% of the total root surface area was in the surface 0.3 m of the soil, while 6% was below 1.35 m. However, within a horizontal distance of 1 m from the bole of a tree, 42% of the roots were in the surface 0.3 m and 24% were below 1.35 m. Roots less than 2 mm in diameter made up 50% of the total root surface area. Results indicate that vegetative propagules develop equally as well as seedling stock and that both root profusely to a depth of 2.5 m.
Microbial Degradation of a Montmorillonite‐Dextran Complex
Authors: Olness Alan , Clapp C. E.
Published: July 2010

Microorganisms capable of metabolizing the detran B‐512F were isolated from a Webster clay loam soil. Suspension of cells were added to polysaccharide solutions or suspensions of clay‐polysaccharide complexes in Warburg respirometers. Oxygen uptake curves, divided into three stages, indicated that the dextran was partially protected in the presence of clay. Rates of oxygen uptake in stage I (1 to 3 hours) were much higher for the systems with dextran alone than for those containing clay‐dextran complexes. Rates for stages II (4 to 6 hours) and III (7 to 48 hours) were about equal for systems containing the same amount of dextran. The uptake rate in the first stage indicated a linear relationship to the amount of clay present, while the second stage was related to the amount of dextran initially present.
Transformation of Hydroxyapatite to Fluorapatite
Authors: Wier D. R. , Chien S. H. , Black C. A.
Published: July 2010

When solid hydroxyapatite and solid calcium fluoride were equilibrated at 25C with dilute solutions of HCl, analysis of the solutions yielded an average value of 118.8 for the negative logarithm of the ion‐activity product for fluorapatite (10 pCa + 2 pF + 6 pPO4). This value compares favorably with values of 118.4, 119.2, and 120.9 reported by other investigators for the negative logarithm of the activity solubility‐product constant for fluorapatite. A plot of the negative logarithm of the activity‐product of (H)3(PO4) against the negative logarithm of the activity‐product of (Ca)(OH)2 in solution yielded a regression line with a slope of −1.52, which is close to the theoretical value of −1.50 for fluorapatite in a solution saturated with calcium fluoride and is greater than the theoretical value of −1.67 for hydroxyapatite. The results indicate that at least the surface of the hydroxyapatite had been converted to fluorapatite during the equilibration with solid calcium fluoride.
Interaction Effects of Boron and Lime on Barley
Authors: Gupta Umesh C.
Published: July 2010

A greenhouse study involving six levels of B and four levels of lime was conducted on barley (Hordeum distichon L., cultivar ‘Herta’). Boron toxicity symptoms occurred at 0.5 to 4.0 ppm applied B, with the most severe symptoms occurring at 4.0 ppm B level at soil pH 5.3. At 0.5 ppm B, no visible symptoms occurred at pH values of 6.3 and 6.8, and at 1.0 ppm B no symptoms occurred at pH 6.8. There was a highly significant soil pH × B interaction, in which high rates of B were more detrimental to kernel yields at lower pH than at high pH values. The highest kernel yields were recorded with 0.25 ppm B at soil pH 5.8. An application of 4.0 ppm B at soil pH 5.3 and 5.8 did not produce any kernels.

The B concentrations of boot stage tissue (b.s.t.) and straw showed a B × pH interaction resulting in decreased B with increasing rates of lime. The lowest concentrations of 1.9 to 5.1 ppm B were found in the B1 treatments. A B concentration of about 12 ppm in the b.s.t. and of 7 ppm in straw at soil pH 5.8 appeared to be related to maximum yields. Boron deficiency was related to B concentrations of about 2 to 5 ppm and Ca/B ratios of about 540 and higher in the b.s.t. A Ca/B ratio of about 180 appeared to be optimum, while ratios of 10 to 45 were in the severe B toxicity range. The Ca/B ratios of > 697 in straw were associated with B deficiency. A Ca/B ratio of 260 appeared to be sufficient and ratios of 7 to 22 were related to severe B toxicity.

A range in the B concentration of 1.4 to 9.9 ppm and in Ca/B ratio of 343 to 1,159 in the b.s.t. collected from Prince Edward Island fields indicated a deficiency of B in many soils for growing barley. However, no visible B deficiency symptoms were found either under greenhouse or field conditions.
White Phosphorus as a Phosphatic Fertilizer
Authors: Rodriguez Armando , Bohn Hinrich L. , Johnson Gordon V.
Published: July 2010

White P, in amounts equivalent to phosphate fertilization rates, oxidized within 2 days in soils. Sorghum (Sorghum vulgare Pers.) and tomatoes (Lycopersicon esculentum Mill.) responded equally to white P and NH4H2PO4 in greenhouse tests of neutral and calcareous soils. In an acid soil, the growth rate was delayed initially in the white P treatments compared to phosphate. Later growth narrowed the gap between the phosphatic sources. After liming the acid soil, the growth delay was absent and the yields from white P treatments were as great as from NH4H2PO4. No evidence of phytotoxicity was found in these experiments.
Fractional Water‐Sediment Sampler
Authors: Heinemann William H. , Brown Melvin J.
Published: July 2010

The fractional water‐sediment sampler enables collecting large‐volume representative samples of water and sediment from surface drainage streams. Free fall‐flow, such as obtained at drop structures, is required for the operation of the sampler. The total sediment‐laden water flow sampled can be split to 50 or 25% of the original sampled flow before being directed to containers by adding one or two splitting stages.