bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractStored 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

AbstractAn 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

AbstractBoron 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

AbstractAdsorption 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

AbstractTwo 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

AbstractRoots 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

AbstractBentonites 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

AbstractWater 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

AbstractCurves 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

AbstractSoils 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

AbstractThe 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

AbstractClay 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

AbstractPhysical 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

AbstractThe 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

AbstractAlthough 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

AbstractA 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

AbstractColonies 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

AbstractTriammonium 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

AbstractRoot 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

AbstractMicroorganisms 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

AbstractWhen 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.