bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salt Tolerance of Mexican Wheat: II. Relation to Variable Sodium Chloride and Length of Growing Season
Authors: Bernal Carlos Torres , Bingham F. T. , Oertli J. 
Published: July 2010

AbstractGermination, seedling growth, and grain production of four short‐season, one intermediate‐season, and three long‐season varieties of Mexican wheat (Triticum aestivum) were studied in relation to variable NaCl salinity. Germination counts after 7 days exposure to NaCl solutions in petri dishes revealed that the wheats as a group are relatively tolerant, germinating freely in the presence of −16‐ to −20‐atm osmotic potential. ‘Nadadores,’ ‘Potam,’ ‘Sonora,’ and ‘Nuri’ were the most tolerant; ‘Ciano,’ ‘Cajeme,’ and ‘Yecora,’ the least at germination. Tolerance at germination was not associated with any obvious properties such as length of growing season or seed hardness. The eight wheat varieties were grown from seedling stage to maturity in sand cultures with a complete nutrient solution containing sufficient NaCl to produce total osmotic potentials of −0.5, −2.5, and −4.5 atm. Leaf samples were collected at spike emergence for chemical analysis including NO3‐N, Cl, and Na. Plots of relative grain yield in relation to osmotic potential of substrate revealed two general relationships, one for the short‐season varieties and one for the long‐season varieties. Fifty percent yield decrements were associated with −3 atm and −6 atm for short‐season and long‐season varieties, respectively. Further, relative grain yields under a given NaCl stress were correlated with the length of the maturity period. Chemical analyses of leaf samples collected at spike emergence showed higher Na and Cl contents in short‐season varieties than in long‐season varieties. Thus, Na and Cl toxicities may be involved in growth depressions. Also, leaf analysis data revealed an inhibitory effect of Cl upon NO3‐N accumulation.
Evaluation of Six Extractants for their Ability to Predict Manganese Concentrations in Wheat and Soybeans
Authors: Shuman L. M. , Anderson O. E. 
Published: July 2010

AbstractSix extractant procedures were evaluated for their ability to relate soil Mn to Mn concentrations in wheat (Triticum aestivum) and soybeans (Glycine max L. Merr.) over three soil pH levels (pH 4.8, 5.8 and 6.8) and three rates of Mn addition. Eight Southeastern soils were treated with 0, 25, and 50 ppm Mn for wheat and 0, 2.5, and 25 ppm Mn for soybeans and the crops were grown 40 days in the greenhouse. Correlation coefficients were computed for plant Mn in relation to soil Mn extracted using six extractants: water, neutral 1N NH4OAc (with and without 0.2% hydroquinone), “double acid,” diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminedi‐o‐hydroxyphenylacetic acid (EDDHA). For wheat the correlations between soil Mn extracted with both water and 1N NH4OAc and plant Mn were consistently high over the entire pH range. However, for soybeans only water had a high coefficient at pH 4.8 while DTPA and the “double acid” extractants gave food correlations at the higher two pH levels. For wheat, DTPA also gave consistently good correlations. Considering both crops studied, it was concluded that at pH 5.8 and 6.8 DTPA gives the best measure of plant available Mn in acid Southeastern soils. At pH 4.8, water would be the extractant of choice. Double acid, EDDHA, and 1N NH4OAc were intermediate in their ability to predict plant Mn concentrations and 1N NH4OAc plus hydroquinone was inferior for both crops.
The Exhaustive Alkaline Cupric Oxide Oxidation of Humic Acid and Fulvic Acid
Authors: Neyroud J. A. , Schnitzer M. 
Published: July 2010

AbstractA humic acid and a fulvic acid were subjected to successive oxidations with alkaline cupric oxide at 170C for 3 hours until identifiable degradation products were no longer formed. Resistant humic acid and fulvic acid residues were then oxidized with alkaline permanganate. Following each oxidation, the degradation products were extracted into ethyl acetate, methylated, separated by column, thin‐layer and gas‐chromatography and identified by mass spectrometry and micro‐IR spectro‐photometry.The exhaustive alkaline cupric oxide oxidation of 1.0 g of humic acid yielded 109.0 mg of aliphatic compounds (mainly succinic acid and the n‐C16 and n‐C18 fatty acids), 94.9 mg of phenolic acids and 36.2 mg of benzene‐carboxylic acids. Oxidation of 1.0 g of fulvic acid produced 104.7 mg of aliphatic compounds, 146.7 mg of phenolic acids and 35.1 mg of benzene‐carboxylic acids. The resistant humic and fulvic acid residues yielded on further oxidation with alkaline permanganate additional amounts of benzene‐carboxylic acids.Compared to other degradation methods, alkaline cupric oxide oxidation of humic substances was found to be an efficient procedure for the formation of relatively large amounts of aliphatic and phenolic degradation products but was less effective for degrading aromatic structures linked by C‐C bonds only. The main reaction governing the alkaline cupric oxide oxidation of the humic substances appeared to be alkaline hydrolysis. The data indicate general similarities in the chemical structures of the two humic materials but with the fulvic acid containing more phenolic structures than the humic acid.
Denitrification Losses from Humid Tropical Soils of Puerto Rico
Authors: Dubey H. D. , Fox R. H. 
Published: July 2010

AbstractProfile samples from 5 depths (0–25, 25–50, 50–75, 75–100, and 100–125 cm) from 3 soil types (two Oxisols—Piña sandy loam and Catalina clay, and an Ultisol—Humatas clay) were incubated at 23±1C under field capacity and waterlogged conditions in an oxygen‐helium atmosphere. Evolved N2 and N2O were determined after 1 and 2 weeks by gas chromatography.Denitrification was related to moisture level, organic matter content, pH, and denitrifying population. Gaseous‐N losses occurred almost exclusively from the surface soil (0–25 cm) under waterlogged conditions. Losses ranged from 8 to 31% of the applied NO3‐‐N. Some loss (7%) also occurred at field capacity from the surface horizon of the Oxisol having the highest organic matter content, Catalina clay. Losses were directly related to organic matter content. Raising the pH of the subsoil only enhanced denitrification slightly. Addition of a denitrifying population and mineral nutrients in the form of a soil inoculant to a subsoil with a raised pH and organic matter content increased denitrification equal to that of surface soil. The lack of denitrification at lower depths is believed to be due to an inadequate supply of rapidly available energy material, low pH and mineral nutrients, and consequent lack of a denitrifying population. Since the surface soil rarely gets waterlogged, it was concluded that little possibility of N losses by denitrification in these humid tropical soils exists.
Infrared Absorption Similarities between Hymatomelanic Acid and Methylated Humic Acid
Authors: Tan K. H. 
Published: July 2010

AbstractInfrared analysis was conducted comparing hymatomelanic acid and methylated humic acid extracted from two Ultisols and one Inceptisol. The results revealed close similarities in spectrograms, leading to the assumption that hymatomelanic acid was not an artifact, but a naturally esterified or methylated fraction of the humic molecule liberated by ethanol extraction. Carbon‐14‐labeled ethanol extraction of humic acid yielding hymatomelanic acid showing radioactivity counts below the control supported the assumption for the natural occurrence of hymatomelanic acid. Methylation of humic and hymatomelanic acids increased the infrared absorption between 3000 to 2800 and at 1720, 1460, and 1400 cm‐1, for C‐H, carbonyl, CC‐H3, and carboxyl stretching vibrations, respectively. Separation of the ester group from the hymatomelanic acid molecule by dissolution with 2N NaOH and HCl eliminated its blocking effect on the carboxyl vibration in COO‐ form and the absorption at 1620 cm‐1 regained in intensity.
Lithologic Discontinuities in Loessial Soils of Southwestern Kentucky
Authors: Price T. W. , Blevins R. L. , Barnhisel R. I. , Bailey H. H. 
Published: July 2010

AbstractEleven soil pedons representing three soil series, commonly mapped as loess over contrasting residuum in southwestern Kentucky, were studied. Numerous tests were conducted to determine which parameters are most reliable in discerning loess from underlying residuum and at the same time to obtain more complete characterization of these soils. Soils studied include the Bedford (Typic Fragiudults), Crider (Typic Paleudalfs), and Zanesville (Typic Fragiudalfs) series. Quartz/feldspar ratios indicate that the three soil series are very similar in the upper horizons, but somewhat different in the lower horizons, and have clear lithologic discontinuities. The occurrence and location of this discontinuity in the soil pedon as determined by the quartz/feldspar parameter agree closely with the pedon morphology described in the field. Particle size distributions indicate that the upper horizons of all the pedons are very similar, particularly in silt content. Particle size distributions also indicate a clear lithologic discontinuity in each of the Bedford and Zanesville soil pedons but do not show a clear boundary for Crider soils. Results from particle size analysis, quartz/feldspar ratios and field observed morphology indicate the presence of a thin loess mantle over differing residuum in these southwestern Kentucky soils.
Curling Inhibition of Clays Mounted on Slides for X‐Ray Diffraction Analysis
Authors: Rich C. I. 
Published: July 2010

AbstractA method is proposed which effectively inhibits curling of clay specimens on slides used for X‐ray diffraction. Glass wool is broken into short lengths and mixed with the clay suspension before drying. Heat treatments and K‐saturation can be performed without curling and loss of the sample.
A Field Study of Soil Water Depletion Patterns in Presence of Growing Soybean Roots: I. Determination of Hydraulic Properties of the Soil
Authors: Arya L. M. , Farrell D. A. , Blake G. R. 
Published: July 2010

AbstractThe hydraulic properties of a Waukegan loam profile were determined by field and laboratory procedures. Pressure‐water content relationships obtained in the laboratory were found to be variable at pressures above −100 cm of water. In this range field data were considered more reliable.Hydraulic conductivity in the field was determined from flux and hydraulic‐head gradient data. Hydraulic‐head gradients were obtained from tensiometric measurements of pressure at various depths. In the soil profile that was subject to both evaporation and drainage, the position of a downward moving “zero flux” boundary was determined. Flux across any depth was obtained by integrating the rate of change of water content with time between the “zero flux” boundary and the depth in question.A modified laboratory technique was used to determine the diffusivity of undisturbed soil cores. Water content vs. distance data were obtained subject to the conditions that evaporation was proportional to the square root of time and the soil core was effectively semi‐infinite. A diffusivity equation developed by Bruce and Klute (1956) was used to calculate diffusivity from the water content‐distance functions. Diffusivities were converted to conductivities.The “zero flux” boundary technique greatly reduced the time needed by covered plot methods to obtain conductivities at high soil‐water pressures. The laboratory procedure required only about 30 min/sample and gave results that compared favourably to field results.At high water contents and to a depth of 20 cm, field conductivities were slightly lower than laboratory estimates. Below the 20‐cm depth field data tended to be slightly higher.
The Effect of Soil Properties on Zinc Adsorption by Soils
Authors: Shuman L. M. 
Published: July 2010

AbstractSolutions containing eight different concentrations of Zn were equilibrated with four soils sampled at two depths to determine whether Zn adsorption conformed to the Langmuir isotherm and to relate the Langmuir coefficients to soil properties. Zinc adsorption conformed to the Langmuir isotherm and two linear portions of the curve were found. The adsorption sites for the lower part had very high bonding energy coefficients and low adsorptive capacities compared with the adsorption sites of the part of the curve corresponding to higher Zn concentrations in the equilibrating solution. The CEC was related to the adsorptive capacity. The lower part was equivalent to 23% of the CEC and the upper part to 76% of the CEC. Soils high in clay or organic matter had higher adsorptive capacities and higher bonding energies for Zn than sandy soils low in organic matter. More differences in Zn adsorption were observed among soil types than between depths in each soil type. A study of the effect of pH on the adsorption of Zn revealed that low pH reduced Zn adsorption more for the sandy soils than for those high in colloidal‐size materials.
Validity of Soil‐Water Samples Collected with Porous Ceramic Cups
Authors: Hansen Edward A. , Harris Alfred Ray 
Published: July 2010

AbstractLaboratory and field tests were made to determine if porous ceramic cups collect representative samples of nitrate and phosphate from soil water. Substantial bias and variability were found. Some of the sources of sample bias were sorption, leaching, diffusion, and screening of phosphate ions by the cup walls. Sample variability of nitrate ions was strongly influenced by sampler intake rate, plugging, sampler depth, and type of vacuum system (which simulated different sampler sizes). These factors affect timing of sample collection and, because nutrient concentration in soil water is continually changing, they in turn affect sample concentration. These factors produced as much as a 60% range in sample concentration from eight samplers installed in a small uniform plot. Added to this variability is an unknown amount of bias representing the difference between the sample concentration and the average drainable soil‐water concentration. The many factors affecting the sample concentration together with the demonstrated variability and unknown bias make interpretation of sampler data difficult. To reduce sample variability, group samplers by intake rate, and use short sampling intervals, uniform sampler lengths, and the same initial vacuum for all samplers.
Soil Bulk Densities after Thirty Years under Different Management Regimes
Authors: Northup M. L. , Boyle J. R. 
Published: July 2010

AbstractVariability of soil bulk density must be known to convert accurately concentrations of nutrients in a soil to absolute quantities. This study shows that cultivation increases the bulk density of some soils and simultaneously lowers its variability. Establishment of prairie and pine (Pinus spp.) vegetation on cultivated soils has not created significant differences in this property between vegetation types in 30 years.
Hydraulic Conductivity Calculations for Unsaturated Steady‐State and Transient‐State Flow in Sand
Authors: Elzeftawy Atef , Mansell R. S. 
Published: July 2010

AbstractUsing a method employed by Green and Corey (1971), hydraulic conductivity was calculated as a function of water content for Lakeland fine sand. A gamma ray transmission method for measuring soil water content and a tensiometer‐pressure transducer arrangement for measuring soil water suction were also used to experimentally determine values of hydraulic conductivity for a similar range of soil water contents in undisturbed soil cores and hand‐packed soil columns. Measured and calculated values were in good agreement for steady flow.During transient flow soil water content was observed to be a non‐unique function of suction for water desorption, but depended upon the state of flow. Higher water contents were found at a given pressure head during unsteady flow than during steady flow or static equilibrium (zero flow). Graphs of water content versus soil water suction were similar for cases of steady and no‐flow conditions. For transient flow, the soil‐water pressure depended upon the soil‐water content and rate of change of pressure head with time.
Micronutrient Levels in the Rice Plant Y Leaf as a Function of Soil Solution Concentration
Authors: Yoon S. K. , Gilmour J. T. , Wells B. R. 
Published: July 2010

AbstractA field experiment was established to evaluate the rice plant (Oryza sativa L. var Bonnet 73) Y leaf Fe, Mn, and Zn content versus soil solution concentration as a function of time. Rice straw additions were made to provide variable submerged soil solution chemistry. Rice straw amendments facilitated Fe and Mn release to the soil solution. Bicarbonate, hydroxide, and possibly organic ligands from the rice straw appeared to lower soil solution Zn concentration. Rice plant Y leaf analyses suggested that the oxidative status of the rice root system exerted some control over Fe and Mn content. Zinc content in the rice plant Y leaf followed submerged soil solution levels.
Geomorphology of a Glaciated First‐Order Valley in South Central New York
Authors: Daugherty L. A. , Hanna W. E. , Arnold R. W. 
Published: July 2010

AbstractA glaciated first‐order valley in south central New York was studied to determine the post‐glacial evolution of the landforms. Ninety‐seven profiles were sampled at depth intervals of approximately 30 cm to determine internal features of the landscape units. Particle size differences were the main indicators of lithologic discontinuities. Arithmetic mean of the fine earth particle size in conjunction with the relative amounts and orientation of coarse fragments were useful in determining strata of the summit, shoulder, backslope, footslope, toeslope and the high, intermediate, and low level terraces. Congeliturbate as much as 10 m deep was found in the basin at the head of the stream in foot‐ and toeslope areas. The downstream portion of these deposits has been deeply entrenched by the stream. During periglacial times congeliturbate in the downstream channel contributed to temporary base levels of the stream. Much of this congeliturbate remains as terraces. The alluvium resulting from the entrenchment of the congeliturbate occurs as a series of 92 terrace remnants and it is believed that their strata, relative elevation, and gradient contain clues to the complex sequence of erosional and depositional events.
Vehicle Perturbation Effects upon a Tundra Soil‐Plant System: I. Effects on Morphological and Physical Environmental Properties of the Soils
Authors: Gersper P. L. , Challinor J. L. 
Published: July 2010

AbstractChanges obtaining in the soil abiotic physical environment due to tracked‐vehicle disturbance were determined in Tundra soils near Barrow, Alaska. The study was a contribution of the U.S.I.B.P., Tundra Biome Program.Six years following the scarring of the tundra surface by several years of infrequent passage by tracked‐vehicles (Weasel), the soils within the track had higher bulk densities and temperatures, accelerated and deeper thaw, and lower moisture percentages than undisturbed soil. Soil morphology was little altered except for direct physical alteration of surface organic horizons and a slight increase in mottling of mineral horizons in all but the wetter portions of the track. The intensity of alteration and associated environmental changes were related to the degree of evident disturbance (the amount of visible damage to the vegetative cover and soil surface) which, in turn, were related to differences in the natural drainage of the soils along the tracks; disturbance being greater, the poorer the natural drainage.The study indicated that a slight amount of disturbance to the tundra surface may be beneficial in terms of increased productivity and nutrient content of vegetation (see Part II of this paper). On the other hand, heavy disturbance can result in severe damage to the tundra system due to subsidence and erosion preventing the revegetation of the disturbed areas.
Water Flux and Electrical Potentials in Water‐Saturated Bentonite
Authors: Gairon S. , Swartzendruber D. 
Published: July 2010

AbstractElectrical potential, water flux, and hydraulic gradient were studied for saturated water flow through plugs of sodium bentonite at concentrations ranging from 11.5 to 35.1% clay. A special permeameter with an adjustable piston allowed measurements to be taken with a given mass of clay, but with successively lower clay concentrations as the piston was shifted out to increase the water content of the clay‐water mixture. At the lowest clay content, both electrical potential and water flux increased less than proportionally with increasing hydraulic gradient. This less‐than‐proportional behavior decreased as clay concentration increased, and, at 28.4% clay, proportional response to hydraulic gradient was obtained for both electrical potential and water flux. A less‐than‐proportional relationship between electrical potential and hydraulic gradient did not cause the water flux to increase more than proportionally with increasing hydraulic gradient, in contrast with what has been reported for nonswelling quartz powder and would be inferred from the classical double‐layer theory of streaming potential and electroosmotic flow. The relationship between electrical and hydraulic properties may thus be different for swelling porous media than for nonswelling media. The only indication of a more‐than‐proportional flux‐gradient relationship was found for a 35.1% clay concentration, in the form of a linear relationship displaced to the right from the origin to yield a positive gradient intercept and a negative water flux at zero hydraulic gradient.
Nitrogen, Phosphorus, and Potassium Requirements in No‐Tillage and Conventionally Tilled Corn
Authors: Moschler W. W. , Martens D. C. 
Published: July 2010

AbstractThe response of corn (Zea mays L.) to four rates each of N, and P, and three rates of K fertilizer was determined under no‐tillage and conventional tillage culture. The soil type was Jefferson silt loam, an infertile, acid soil. The experiments were conducted during 3 years of above‐average rainfall for the location. In conventional tillage culture the fertilizer was broadcast on turnplowed soil and disked in, while in no‐tillage culture it was broadcast and left on the soil surface. The objective was to clarify the relative fertilizer requirements of corn grown by the two tillage methods. Yield, nutrient element removal by the crop, and residual levels of nutrient elements were used to evaluate results. Results obtained by yield and nutrient removal criteria agreed with each other except at the higher rates of P, and K. In these cases considerable P, and K were absorbed without corresponding yield increase. Corn maturity was hastened by no‐tillage. It was concluded that at the highest rate of N, and all rates of P, and K tested, no‐tillage culture increased the efficiency of the applied fertilizers. The highest yield producing 3‐year total rates of N, P, and K tested with no‐tillage were 470.8, 67.3, and 215.2 kg/ha, respectively. At these rates the grain yield increases over conventional tillage receiving the same rates were 19.1, 18.3, and 14.6%, respectively. These increases in fertiliezr efficiency are of special value in times of food and fertilizer shortages, such as presently exist.