bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Critical Zn2+ Concentration for Corn and the Nonabsorption of Chelated Zinc
Authors: Halvorson A. D. , Lindsay W. L. 
Published: July 2010

AbstractCorn (Zea mays) was grown in nutrient solutions of pH 5.2 and 7.5 with EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid) as chelating agents. At pH 5.2, corn plants were healthy and fully green, but at pH 7.5, the nutrient solutions with DTPA produced severely stunted, Zn‐deficient plants. Spraying the foliage with Zn or increasing the level of ZnSO4 added to the nutrient solution prevented Zn deficiency.A concentration of 10−10.6 M Zn2+ was sufficient to prevent Zn deficiency with corn. Even at 105 times this concentration, chelated Zn was not absorbed by the roots. Equilibrium relationships of chelating agents in hydroponic solutions were extremely helpful in interpreting the results of this study.The findings reported herein support the hypothesis that Zn2+ is the form of Zn absorbed by plant roots. Furthermore, plants can obtain adequate Zn from a nutrient media when Zn2+ is maintained at approximately 10−10.6 M. This concentration is nearly 4,000 times lower than the 10−7 M reported by Carroll and Loneragan. The hypothesis proposed herein is that chelation aids in the transport and movement of metal ions to plant roots, but only Zn2+ is absorbed.
Effect of a Saline and Alkaline Ground Water on Soil Genesis in Semiarid Southern Iran
Authors: Abtahi Ali 
Published: July 2010

AbstractThe Marvedasht and Korbal soil series, developed in the Marvedasht area under similar climatic, vegetation, and parent material conditions, but with different topography and depths to saline ground water, were investigated. Marked differences in the morphological, physical, chemical, and mineralogical properties of soil appear to be due to variations in topography and the depth of saline and alkaline ground water.In this toposequence, soils with salic horizons (Salorthid) have formed on the flood plain with shallow ground water and soils with natric horizon (Natrixeralf) on the low terrace with deep ground water.Both soils are calcareous throughout. Exchangeable sodium which is the major cause of clay dispersion and migration is only effective whenever the excess salts have been leached.X‐ray analyses indicate this toposequence has a clear difference in relative occurrence of attapulgite and smectite clay minerals. The attapulgite is replaced by smectite in the drier climatic zones.
Variation in Physical Properties and Mineral Composition of Thin Loess Deposits in the Swift Current Area of Saskatchewan
Authors: Souster W. E. , St. Arnaud R. J. , Huang P. M. 
Published: July 2010

AbstractThe nature and distribution of thin loessial deposits occurring on the Swift Current Plateau in southwestern Saskatchewan were studied. Results of physical and mineralogical investigations confirm the eolian origin of the material and support the separation of these loessial soils from adjacent lacustrine soils for mapping purposes.A definite thinning trend is apparent along a southeasterly transect across the area. The particle‐size distribution of the material is very similar to typical loess and the phi median diameter of individual samples increases progressively with increasing distance from the source.Mineralogical analyses provide evidence of a sorting action during deposition of loess which is controlled by particle shape. Quartz and potassium feldspars, both 3‐dimensional tektosilicates, remain constant in very fine sand and silt fractions across the loess transect. In contrast, a marked concentration of platy micaceous minerals occurs in coarser fractions and their depletion is noted in finer fractions with transport distance. This sorting serves to explain previously anomalous trends in total K contents of size fractions as a function of distance reported for loessial deposits by other workers.
Dissolution Rates of Phosphate Rocks
Authors: Chien S. H. 
Published: July 2010

AbstractThe activity concept of phosphate‐rock solubility was tested kinetically with three phosphate rocks covering a wide range of solubility. Two approaches were used: a single extraction solution of low solid/solution ratio (0.2 g/500 ml) and successive extractions at a high ratio (5 g/500 ml). The solution used was 1N NH4OAc (pH 4.8). The results showed that the phosphate rocks differed in their solubility and each rock apparently contained two fractions which differed in solubility. The rate constant was found to depend on the degree of carbonate substitution for phosphate in apatite structure and the solid/solution ratio used.
A Modified Mercury Tensiometer
Authors: Savvides Loucas , Ayers Robert S. , Ashkar Mahmoud 
Published: July 2010

AbstractThe present paper introduces a modified type of Hg tensiometer. The manometer in this tensiometer uses the usual principal as for other Hg manometers. However, the main difference is that the Hg manometer is contained within the tensiometer body itself. A relatively small volume of Hg is used and the small mercury reservoir can be filled or emptied rather easily. Once the reservoir is filled, the mercury can usually be safely left for the lifetime of the tensiometer. Tensiometers of the proposed design have been handled successfully for scheduling irrigation on shallow soils by unskilled farmers in Cyprus for the last 4 years.
Experimental Test of the Langevin Equation as a Model for Water Flow Through Unsaturated Soil
Authors: Sposito Garrison , Sullivan Patrick J. , Gupta Vijay K. 
Published: July 2010

AbstractIn this paper the parameters that appear in the Langevin Equation, a molecular model for the flow of water through soil, are expressed as functions of the hydraulic conductivity, the water diffusivity, and the soil water matric potential. Since the parameters must have values lying within certain ranges in order that the Langevin Equation and the Markovian hypothesis on water flow that comes from it be applicable, it is possible to test the equation and the hypothesis experimentally. The results for 15 different soils show that the equation and the Markovian hypothesis are consistent with soil water data for homogeneous, unsaturated soils throughout the normal field range of water content.
Hydrolysis and Decomposition of Calcium Montmorillonite
Authors: Frenkel Haim , Suarez Donald L. 
Published: July 2010

AbstractThe extent to which exchangeable calcium hydrolysis occurs during the preparation of homoionic calcium montmorillonite clay and the rate of the reaction in distilled water at various supension concentrations and levels of CO2 was determined at 25°C. The rate and extent of hydrolysis was found to be comparable to that reported for sodium montmorillonite and increased with CO2 concentration. CEC was appreciably reduced during washing of residual salts while preparing calcium montmorillonite. The mechanism of hydrolysis is discussed.
Nitrate Dissimilation and Population Dynamics of Denitrifying Bacteria During Short Term Continuous Flow
Authors: Volz M. G. , Starr J. L. 
Published: July 2010

AbstractA solution containing 100 µg ml−1 of NO3‐‐N, 200 µg ml−1 of glucose‐C, and 0.01N CaSO4 was supplied continuously to soil in acrylic plastic columns (6‐cm inside diam × 10‐cm length) for up to 96 hours while N2 gas was passed through the system. Concentrations of NO3‐‐N in the effluent decreased to 20 µg ml−1after 60 hours. Simultaneously, NO2‐‐N concentrations increased from traces to 65 µg ml−1 and more than 70% of applied C had been utilized after 60 hours. These results indicate that most C oxidation was coupled with NO3‐ reduction although nearly all applied NO3‐ was ultimately denitrified after 96 hours.Denitrifiers estimated by a most probable number (MPN) technique increased from 1.1 × 103g−1 oven‐dry soil to maximum populations of 1.9 × 107 g−1 during 96 hours of infiltration. From measured biomass increases and soluble N concentrations as functions of soil depth at “quasi” steady states during the course of the experiment, specific denitrification rates per microbe, rd, were determined. These values ranged from 1.3 × 10−5 to 6.8 × 10−7 (µg N ml−1) hour−1 per denitrifier for 18 to 96 hours respectively; the decrease may have been due to the activities of different denitrifier species.A heat shock treatment of soil which had been sampled before, during, and after the experiment and was then suspended in sterile distilled water indicated that most denitrifiers were present as vegetative cells, especially after 18 hours. In addition, after 96 hours a gram negative rod unclassified CDC VA‐1, very closely related to Pseudomonas cepacia, capable of growth on yeast extract agar and in vitro denitrification was the sole denitrifier species isolated at dilutions near extinction using a MPN technique. These data indicate that, irrespective of the physiological diversity of denitrifier species present prior to anaerobiosis, a single bacterial type may become dominant as a result of a given set of environmental conditions.
Quantitative Relationships Among Nutrients Leached From Soils
Authors: Terman G. L. 
Published: July 2010

AbstractThis study was undertaken in an attempt to quantify relationships among anions (An) and cations (Cat) leached from soils. Several sets of published data on leaching of ions from acid and nonacid soils were evaluated by linear regression calculations based on the chemical equivalency of Σ Cat and Σ An leached. Calcium, Mg, K, and Na comprised most of Σ Cat, and NO3, SO4, and Cl, most of Σ An. Bicarbonate (HCO3) is also leached from nonacid soils; H is assumed to account for most of the excess of Σ An over Σ Cat in leachates from acid soils. The regression coefficient for each cation on Σ An indicates its contribution to anion leaching and that for each anion on Σ Cat indicates its contribution to cation leaching. Amounts of each ion leached from a given soil depended largely on amount of soluble ion present and amounts of leachate. Calcium and NO3 tended to dominate Σ An and Σ Cat leached if these ions were applied or were abundantly present in a soil. Magnesium, Na, SO4, and Cl were increasingly important as the proportionate supply of each increased. Potassium was not leached in amounts appreciable enough to influence amounts of anions lost, and HCO3, although present in appreciable amounts in nonacid soils, apparently was not related to Σ Cat leached. Amounts of ions leached were much more closely correlated with leachate volumes among soils and time periods than with leachate volumes from various treatments for a given time period.
Test of a Soil Water Model Under Field Conditions
Authors: Beese F. , Van der Ploeg R. R. , Richter W. 
Published: July 2010

AbstractA 218‐day experiment on a fallow loess soil was carried out to study infiltration and redistribution under natural field conditions. On an experimental plot of 6 by 6 m tensiometers had been installed in 11 depths: 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 cm. They were read at short irregular intervals. The precipitation was measured daily. The hydraulic functions of the layered, horizontal soil and a relation between potential evaporation, actual evaporation, and the soil suction at 5‐cm depth had been established previously. With use of these soil and atmospheric data the unsaturated soil moisture flow equation was solved numerically. Purpose of the numerical analysis was to determine if the unsaturated soil moisture flow equation does describe observed soil moisture behavior for such a long period. It was found that the calculated soil suction values for all depths deviated less than 15% from the measured ones. It is concluded that the unsaturated moisture flow equation can be useful means to supplement field measurements on infiltration, redistribution, evaporation, and internal drainage.
A Quick Method for Estimating Soil Water Diffusivity Functions
Authors: Miller R. D. , Bresler Eshel 
Published: July 2010

AbstractPublished data for horizontal infiltration into air dry (θd) nonsodic stable soil, imply a regression equation D(θ) = 0.001 m2 exp [8(θ‐θd)/(θw‐θd)] where the limit of wetting is θw and m is a constant relating visual position, xf of wetting front at time t, m = xf/(t)1/2. If m isn't constant, D(θ) may not exist.
Factors Influencing the Crust Test for in situ Measurement of Hydraulic Conductivity
Authors: Baker F. G. 
Published: July 2010

AbstractField trials using the crust test were used to determine the influence of five parameters on the saturated and unsaturated hydraulic conductivity values measured on two soils of different structure. These factors were (i) the diameter, (ii) the height of the soil pedestal used in the test, (iii) the degree of soil wetness at which k was measured, (iv) soil structure, and (v) operator effects. Diameter and height were found to strongly affect measurement when they had low values. These two design factors were dependent on the wetness and structure of the soil. Operator differences were small.
Sulfuric Acid as an Amendment for Reclaiming Soils High in Boron
Authors: Prather R. J. 
Published: July 2010

AbstractLaboratory results indicated that sulfuric acid can effectively aid in reclaiming soils high in boron. Results of a study, using 80‐cm columns of a soil high in B, indicated that a surface application of 3.22 metric tons/ha of concentrated (96%) H2SO4 followed by leaching with 3 pore volumes, p.v. of water was nearly as effective in reducing the level of water‐soluble soil B as was leaching with 16 p.v. of water. A direct pH effect on B adsorption affinity can explain the enhanced reclamation effect at the soil surface but cannot account for the beneficial effect found at lower soil column depths. Data suggested that competition by silicate ion for adsorption sites may be contributing to the enhanced desorption of B at lower soil depths.
Enzymatic Activities and Extractable Organic Matter in Soils Invaded by Lycopodium tristachyum Fairy Rings
Authors: Spalding Brian P. , Duxbury J. M. 
Published: July 2010

AbstractThe interaction of fairy rings of Lycopodium tristachyum Pursh. with the soil which they invade was examined by measurement of various soil enzymatic activities and extractable soil organic matter. The activities of cellulase, xylanase, inulinase, α‐galactosidase, invertase, peroxidase, chitinase, and polygalacturonase were enhanced in soil under the rings compared with soil just outside the rings. The activity of urease was lower under the ring while the activity of β‐glucosidase was unaffected. The amount of nitrogen, hexose, and phenolics extracted by 0.01M CaCl2 during autoclaving was enhanced in soil under the ring. The level of reducing substances extracted by dilute buffer and the optical density of buffered extracts were similarly elevated. Extractable lipid, humic acid, and β‐humus were independent of soil location. Significant correlations between some readily extractable organic components and the activities of chitinase, invertase, xylanase, and α‐galactosidase in the soil were observed.
Uptake by Barley of Water Table‐ or Surface‐applied Cadmium
Authors: Kirkham M. B. 
Published: July 2010

AbstractSolutions of Cd were placed for 66 days at the bottom or top of columns (42‐cm long by 15‐cm diam) containing fine sandy loam soil, half of which were planted with barley (Hordeum vulgare L. ‘Liberty’) and half of which were bare, to determine rate of movement upward or downward of Cd. Three solutions with Cd, as CdSO4, were used: distilled water with 0.1 µg/ml Cd; distilled water with 10 µg/ml Cd; secondary effluent with 10 µg/ml Cd. An average of 200 ml/day was added to the top or bottom of columns with plants; there was no drainage water with top additions. An average of 100 or 50 ml/day was added to the top or bottom, respectively, of columns without plants. Drainage water, which collected at the bottom of columns without plants and watered from the top, was analyzed daily for Cd. Plants and soil were analyzed weekly for Cd concentration.In less than 7 days, Cd applied at the surface moved to the bottom and Cd applied at the bottom moved to the surface. At harvest, plants treated with Cd at the bottom contained up to three times more Cd than plants treated with Cd at the top because roots of plants with Cd at the bottom contained higher concentrations of Cd than roots of plants in columns with Cd at the top. Columns without roots had higher concentrations of extractable Cd than columns with roots. Concentrations of Cd in leachate from columns receiving 10 µg Cd/ml effluent were about two times higher than concentrations of Cd in leachate from columns receiving 10 µg Cd/ml water. About the same amounts of Cd were leached out of columns receiving 0.1 µg Cd/ml water or 10 µg Cd/ml water. The results showed that barley roots more readily absorbed Cd placed in a shallow water table than Cd placed in the soil surface.
Distribution Pattern of Inorganic Nitrogen Following Anhydrous Ammonia Injection into a Vertisol
Authors: Khengre S. T. , Savant N. K. 
Published: July 2010

AbstractDistribution patterns of inorganic forms of N and diffusion coefficients of NH4+ were studied after injection of 800 mg of anhydrous NH3‐N per dish, each dish containing 1 kg of soil (Vertisol, bulk density 1.20 g/cm3) maintained at 1/3‐bar moisture percentage and incubated for 120 days. Bell‐shaped distribution patterns of NH4+ and undissociated NH3(aq) were observed. Diffusion coefficients of NH4+ decreased with incubation time. During a 15‐day incubation period, diffusion coefficients of NH4+ increased with increase in moisture content up to 36% (cm3/cm3), but decreased with further increase in moisture content. A temporary accumulation of NO2‐‐N was noticed up to 30 days of incubation at the periphery, but eventually NO2‐‐N was observed near the injection point through 90 days. Production of NO3‐‐N was first observed at the periphery followed by virtually even distribution throughout the retention zone.
The Soils of the Intertidal Zone of Rookery Bay, Florida
Authors: Coultas C. L. 
Published: July 2010

AbstractThe intertidal zone of Rookery Bay, Florida is vegetated primarily with mangrove trees. Mangroves are important to the south Florida fisheries. This work was undertaken to characterize and classify the intertidal soils of Rookery Bay in order to better understand and manage these areas.Most intertidal soils are classified as Typic Sulfihemists‐Typic Sulfaquents. They consist of thin organic deposits over fine sands to sandy clay loam. Spodic Psammaquents also occur at higher elevations. These soils are very poorly drained, saline, and saturated with extractable bases. Most soil samples became more acidic upon drying, probably due to the oxidation of S containing materials. Total S ranged from 0.75% to 1.77% in the sulfidic horizon.
Multiple Tensiometer Flushing System
Authors: Huber M. J. , Dirksen C. 
Published: July 2010

AbstractA system for simultaneous flushing of a large number of tensiometers is described. It includes a multiple shutoff valve and a manometer with movable bottom. Flushing procedures are described; they are fast and simple. It can be used with any direction of installation of tensiometers or tubing, for instance, when all tubing is kept below the soil surface to reduce temperature fluctuations. A concentric tubing arrangement reduces air diffusion into the measuring tubing. The system offers potential for improved data quality and reduced need for flushing.
Field Measured and Simulated Corn Leaf Water Potential
Authors: Reicosky D. C. , Lambert J. R. 
Published: July 2010

AbstractThe dynamic nature and magnitude of field‐measured leaf water potential for sweet corn (Zea mays L.) was compared with that predicted by the model TROIKA. Some plant parameters for corn were estimated from the literature and field observation, whereas the moisture desorption curve and the hydraulic conductivity‐water content relationship were determined for the Varina sandy loam. Leaf water potential‐relative water content relationships were determined in the greenhouse. Hourly microclimate data were used as input to the model, and the predicted and observed values of leaf water potential were compared for 3 days during the growing season. Generally, the model predicted leaf water potential with reasonable accuracy throughout the day. Water potential gradients in the soil were small as compared with those across the root and across the stomatal opening.
Multicomponent Cation Adsorption During Convective‐Dispersive Flow Through Soils: Experimental Study
Authors: Lai Sun‐Ho , Jurinak J. J. , Wagenet R. J. 
Published: July 2010

AbstractThe adsorption of Na+, Mg2+, and Ca2+ from aqueous solutions flowing through soil was examined under different total cation concentrations and input pulse volumes. The pulses of Na+ and Mg2+, which were introduced into a Ca2+‐saturated Yolo loam soil column, appeared separately in the effluent. The degree of separation decreased with total concentration, but was not affected significantly by the pulse volume. At constant total concentration, the initial appearance of the Na+ pulse in the effluent was not affected by input volume; the appearance of the Mg2+ pulse was delayed with increasing pulse volume. The experimental results were compared to theoretical calculations based on a single component linear equilibrium model. At a low loading (a small amount of adsorbate with respect to a large amount of adsorbent), the agreement of the theoretical model and the experimental results was satisfactory. However, when the loading was increased, the discrepancy between the calculated values and the experimental results increased.
Potassium and Rubidium Adsorption and Diffusion in Soil
Authors: Baligar V. C. , Barber S. A. 
Published: July 2010

AbstractUptake of cations by plant roots growing in soil is believed to be influenced by the relative adsorption strengths of cations by soil exchange sites. The adsorption of K and Rb by four soils was investigated to determine the differences in adsorption of K and Rb which may occur and how they are affected by soil properties with the view of using this information to evaluate the uptake mechanisms for K and Rb by plant roots growing in soil.Rubidium was adsorbed preferentially to K by all four soils. Selectivity coefficient kRb/K, indicating the size of the effect ranged from 1.9 to 4.4. Adding K decreased kRb/K, increased the amount of nonexchangeable Rb, and decreased exchangeable Rb. There was a negative correlation (r2 = 0.78) between exchangeable K in the soil and kRb/K. The level of K in the soil had a greater effect on kRb/K than varying types of exchange sites present due to differences in clay and amounts of organic matter in the four soils investigated. The size of the selectivity coefficient indicated that the difference between K/Rb ratios in the solution and exchange phases of these soils used and differences between soils made them suitable for use in plant uptake studies of the mechanisms of K and Rb uptake.
A New Approach to Soil Testing: III. Differential Adsorption of Potassium
Authors: Stout W. L. , Baker D. E. 
Published: July 2010

AbstractDonnán type ratios were used to develop an index to account for the differential adsorption of K in two widely different soils of the Rayne and Hublersburg series. This index was used to calculate an adjusted K requirement for the soils using the approach of Baker. Three corn hybrids (Zea mays L.) were grown in the two soils treated with different levels of K and multiple regression analysis was used to relate soil test variables to plant K content.Most of the variation in the index, KE/S, was associated with soil effects, making the index useful in characterizing the two soils with respect to differential K adsorption and in calculating soil K requirements. Over 60% of the variation in plant K content was explained by the soil K requirement calculated from the index. Compared with a critical K level of 98 ppm exchangeable K for soils with a CEC of 10 meq/100 g and a KE/S of 1.0, the comparable critical values for K were 71 ppm for the Rayne and 114 ppm for the Hublersburg.