bluuebunny/crossref_metadata_2025_split huggingface dataset:
Urea‐Ammonium Sulfate and Urea‐Ammonium Phosphate Evaluation as Nitrogen Sources in the Southeast
Authors: Walker M. E. , Keisling T. C. , Marchant W. H. , Morey D. D. 
Published: July 2010

AbstractRecent increases in N fertilizer cost emphasize the need for information concerning the use of cheaper N sources to produce the most marketable yield per unit fertilizer cost. Urea‐ammonium sulfate (UAS) and urea‐ammonium phosphate (UAP) are two new fertilizer products in which urea is the main source of N. These materials were compared to ammonium nitrate (AN) as N sources for corn (Zea mays L., Coastal bermudagrass (Cynodon dactylin L. Pers.), and rye (Secale cereale L.).Each material was used to supply N at rates from 0 up to 448, 336, and 135 kg/ha on Coastal bermudagrass, corn, and rye, respectively. All crops were grown on Tifton soil (Plinthitic Paleudult; fine, loamy, siliceous, thermic). Corn was also grown on a Greenville soil (Rhodic Paleudult; clayey, kaolinitic, thermic). Recommended cultural practices normally used in the area were followed for each crop. Forage yield for Coastal bermudagrass and rye was measured and selected samples analyzed for ammoniacal N concentration. Corn grain yield was measured. Selected soil samples from the corn experiment were analyzed for nitrate‐N.Percent N increased in Coastal bermudagrass and rye forage as N application rate increased. Coastal bermudagrass recovered less N from both UAP and UAS than from AN at the 336 kg/ha N rate. All materials were equivalent as N sources for rye and corn. Irrigation of the corn was found to increase yields as well as nitrate‐N leaching. Applying 50% of the 336 kg/ha N at planting and the rest later to prevent leaching in corn production was no better on Tifton and Greenville soils than a single preplant N application of either 168 or 336 kg/ha. For Southeastern Coastal Plain conditions the two fertilizers evaluated could replace AN in corn and rye production without loss in N concentration, yield, or N use efficiency. The materials tended to be less efficient than AN in supplying N for Coastal bermudagrass production.
Mineralogy of Soils Developed on Pliocene‐Pleistocene Terraces of the Tombigbee River in Mississippi
Authors: Nash V. E. 
Published: July 2010

AbstractThe clay minerology of four soil pedons formed on Pliocene‐Pleistocene terraces was investigated. These pedons are in the Typic Hapludult, Typic Fragiudult, Aquic Fragiudult, Typic Ochraqualf subgroups and vary, respectively, in drainage from well drained to poorly drained. Smectite was the major mineral in all of the clay fractions with the maximum quantity usually coinciding with the zone of maximum clay accumulation. Hydroxy Al‐interlayered 2:1 clay was generally confined to the upper horizons of these soils. In the deeper horizons, particularly for the poorly drained Aquic Fragiudult and Typic Ochraqualf, the polymeric Al interlayers were replaced by Al(H2O)63+. These soils are all very acid and in the deeper horizons, which are continuously wet, Al‐polymers do not form. In cases where hydroxy Al‐interlayered minerals were deposited by sedimentation the Al‐polymers have been removed. Evidence is presented for a low charge smectite (montmorillonite) and a high charge smectite (beidellite) in these soils. In the surface horizons beidellite is the dominant species with Al‐interlayers, however in the deeper zones both types of smectite are found.
Differential Thermal Characteristics of Soil and Reference Quartz
Authors: Barwood H. L. , Hajek B. F. 
Published: July 2010

AbstractForty‐two reference quartz and soil quartz samples were analyzed by differential scanning calorimetry (DSC) and X‐ray diffraction (XRD). A single α‐β endothermic peak was obtained from 35 samples. Seven samples gave multiple endothermic peak curves. Although XRD indicated that most samples were essentially 100% α‐quartz, DSC peak height to width at one‐half peak height ratios of single peak curves ranged from 5.85 (quartz from sedimentary rocks) to 24.06 (igneous and metamorphic rock quartz). DSC height‐width peak ratios can be used to identify the origin of soil quartz to a specific geologic province (igneous, metamorphic, sedimentary). An apparent variation in quartz ΔH makes quantitation of soil quartz by thermal methods difficult. All but one of the multi‐peaked curves were obtained from vein quartz. No soil quartz showed multiple peaks.
Physical Components of the Diffusivity Coefficient
Authors: Malik R. S. , Laroussi Ch. , De Backer L. W. 
Published: July 2010

AbstractIsothermal horizontal infiltration experiments were conducted in 53–63 µm, 74–88 µm, or 105–125 µm glass bead fractions with water, 6% ethyl alcohol water solution, 20% ethyl alcohol water solution, ethyl alcohol, and methyl alcohol. From these experiments, the diffusivity coefficient was determined using the Bruce and Klute (1956) procedure and D(θ) was established for the fluid content, θ, from 0% to saturation.The D(θ) variation in the fluid content range between 3 and 30% was investigated. The functional relationships between D(θ) and the properties of the fluid, the geometry and the solid matrix were investigated. The physical components of D(θ) were determined using:
urn:x-wiley:03615995:saj2sssaj197903615995004300040001x:equation:saj2sssaj197903615995004300040001x-math-0001 where r* and R* are the mean radius of pores and beads, respectively, σ, µ and ΔHv are the surface tension, viscosity and molar heat of vaporization of the fluid, respectively, and α is the fluid‐solid contact angle.The physical significance of the diffusivity coefficient given by Laroussi and De Backer (1975) defining this coefficient as the ease with which the fluid particles spread from a wetting front, is clarified and confirmed.
A Galerkin in Time, Linearized Finite Element Model of 2‐Dimensional Unsaturated Porous Media Drainage
Authors: Cushman John H. , Kirkham Don , Keller Roy F. 
Published: July 2010

AbstractTwo‐dimensional drainage in porous media by a modified finite element technique is examined. This technique consists of using Galerkin's method on the temporal as well as the spatial dimensions and coupling it with a simple linearizing scheme (considering physical properties constant over individual elements).We apply this method to four separate drainage problems, two of which have been studied previously by other authors. With both of the previous studied problems, our results compared well.
Nature and Properties of Water in Montmorillonite‐Water Systems
Authors: Low Philip F. 
Published: July 2010

AbstractData are presented on several properties of water in montmorillonite‐water systems. The data indicate that these properties differ from the same properties of bulk water because of differences in intermolecular bonding. Also, it is found that the value, J, of each property is described by the general equation J = J° exp β/(mw/mm) in which J° is the value of the given property in pure bulk water, mw/mm is the mass ratio of water to montmorillonite and β is a constant. The proposal is made that, since all of the water properties obey a common equation, their deviation from the corresponding properties of bulk water must be caused by a common factor. By making appropriate substitutions for mw/mm and analyzing the resulting equations, the common factor is shown to be interaction of the water with the surfaces of the montmorillonite layers. The nature of this interaction, and ways in which it might affect intermolecular bonding, are discussed.
Use of Gypsum Stones to Lower the Sodium Adsorption Ratio of Irrigation Water
Authors: Ahmad Bashir , Kemper W. D. , Haider Ghulam , Niazi M. A. 
Published: July 2010

AbstractMany sources of irrigation water have sufficiently high Na+/Ca2+ ratios to be harmful to soils and crops. When the salt contents of the waters are reasonably low, the primary method of lowering this ratio is to apply extra Ca2+ on the fields or in the water. Gypsum is generally the most reasonably priced source of Ca2+. A major portion of its current cost is associated with grinding the stones to a powder and application of this powder to the fields.This study shows that gypsum stones 5 to 20 kg in size are a useable source of the Ca2+ needed to bring down the sodium adsorption ratio (SAR) in sodic irrigation waters. The dissolution rate of the gypsum stones is proportional to the square root of the velocity of flow through the bed. Since the time of residence of solution in the bed is inversely proportional to its velocity through the bed, the increase in concentration of Ca2+ in solution as it passes through the whole bed is inversely proportional to the square root of the velocity of flow. Solution concentration is also inversely proportional to the square root of the size of the stones in the bed.Equations were developed to facilitate design of channels with the proper cross section and length to supply the needed amounts of Ca2+ to the water when the average size of the stones, the flow rate of the water, and the initial ionic concentration of the water are known.
Comparison of Methods to Extract Spores of Vesicular‐Arbuscular Mycorrhizal Fungi
Authors: Smith Garriet W. , Skipper Horace D. 
Published: July 2010

AbstractVesicular‐arbuscular mycorrhizal spores were extracted from soil (pot cultures) using adhesion‐flotation, sucrose‐centrifugation, gelatin column, wet‐sieve, and a new plating method. Counts of 150‐ to 300‐µm diam spores were significantly higher for the plate method by 528, 370, and 258% than for the adhesion‐flotation, sucrose‐centrifugation, and gelatin column methods, respectively. Counts of 100‐ to 300‐µm diam spores were higher for the plate method by 200 and 149% than for the wet‐sieve and modified wet‐sieve methods. Spore counts within four spore size ranges (50 to 100, 100 to 150, 150 to 300, and > 300 µm diam) were greater for the plate method than for the wet‐sieve and modified wet‐sieve methods by approximately four and two times, respectively. The plate method was consistently higher than the wet‐sieve method only for small spores (50 to 100 µm diam) from soybean field soils. Although the new plate method is not applicable for extracting and quantifying large spores (> 100 µm diam) for low spore population soils (field soils), it is recommended for the purpose of quantifying spores in high population soils (> 20 spores/g) as might be encountered in pot cultures.
Studies of Nitrous Oxide Emission from a Grass Sward
Authors: Denmead O. T. , Freney J. R. , Simpson J. R. 
Published: July 2010

AbstractThe exchange of nitrous oxide (N2O) between soils and the atmosphere is believed to play an important part in controlling stratospheric ozone levels, but so far, very little information is available on rates of emission or absorption of N2O by soils in the field. The paper reports measurements of N2O exchange made over 5 months from winter to summer in an unfertilized, mown, grass sward.Ambient air was drawn continuously in an open flow system through the above‐ground portion of a steel cylinder driven into the ground. The enrichment or depletion of N2O in the air stream was measured with an infrared gas analyzer. Exchange rates as small as 1 ng N m−2 sec−1 could be measured.Nitrous oxide was always emitted from the sward, even at very low soil moisture contents. The emission showed a clear diurnal cycle in phase with the temperature of the surface soil; peak emission rates occurred in the afternoon, minima near sunrise. Additions of water as small as 5 mm increased emission rates markedly. Both results suggest that most of the N2O was produced close to the soil surface rather than at depth in the soil profile. Further, the production of N2O was accompanied by a net increase in soil nitrate.Emissions were largest in the spring. With the soil moist to less than field capacity, average daily emissions over periods of several days ranged from 0.6 to 2.5 mg N m−2.
Aluminum Accumulation and Tolerance of Triticale and Wheat in Relation to Root Cation Exchange Capacity
Authors: Mugwira L. M. , Elgawhary S. M. 
Published: July 2010

AbstractSince plant characteristics associated with Al tolerance vary from one species to another, the objective this study was to relate Al tolerance, Al accumulation, root Cation Exchange Capacity (CEC), and exchangeable Al in triticale (X Triticosecale, Witt Mack) and wheat (Triticum aestivum L.). Ten cultivars of the two species were grown in nutrient solutions with 0 or 6 ppm Al added. The solutions were adjusted to pH 4.8 either at transplanting or daily during plant growth. Aluminum accumulation and displacement by Ca and K from roots exposed to Al for up to 24 hours were also determined. With the solution pH adjusted only at transplanting, the relative root lengths (Al/no Al) indicated that the order of Al tolerance was 6TA 298 and 6TA 131 > 6TA 385 > 6TA 203 triticale and Atlas 66 > Thorne and Seneca > Monon > Redcoat and Arthur wheats. Similar Al tolerance ratings were obtained when solutions were adjusted daily to pH 4.8. Correlation coefficients between relative root lengths and root Al concentrations were −0.93** and −0.90** for triticale and −0.85** and −0.063 for wheat, respectively with pH unadjusted and pH adjusted. Correlation coefficients between plant‐induced pH values and root Al concentrations were −0.19 for triticale and −0.79** for wheat. The root CEC values were generally lower in Al‐tolerant than Al‐sensitive cultivars. The results also suggested that the CEC of roots may be a factor in controlling Al absorption in the first 6 hr of plant exposure before the exchange sites are Al‐saturated at longer periods.
Influence of Surface Roughness and Clod Size and Stability on Soil and Water Losses
Authors: Johnson C. B. , Mannering J. V. , Moldenhauer W. C. 
Published: July 2010

AbstractRough cloddy surfaces increased infiltration and decreased soil erosion compared to smoother surfaces as determined by simulated rainfall studies. Overtilling reduced surface roughness and cloddiness. One field experiment showed that a rough surface decreased runoff by 77% and soil erosion by 89% of that from a smooth surface. Tillage of wet soil increased surface roughness, but another field experiment showed that clods resulting from plowing the soil when wet were quite unstable compared with clods from plowing nearer the upper plastic limit. Tilling of compacted soil results in greater cloddiness than tilling of uncompacted soils. However, a laboratory experiment showed that compacted loam clods were less resistant to breakdown by water drop energy than those from uncompacted soil. Compaction of silty clay loam and silty clay soils did not change their stability significantly. To be effective as an erosion control measure, soil clods must be large enough and stable enough to keep infiltration at a high level until the crop canopy covers the soil surface. These studies describe the size and stability necessary to maintain a high level of runoff and erosion control.
Cation Exchange and Selectivity in Heated Minerals
Authors: Komarneni Sridhar 
Published: July 2010

AbstractVarious minerals that are commonly present in shales were heated in air as well as hydrothermally and their cation exchange capacity (CEC) and cation exchange selectivity (CES) values were determined. The CEC values of all the heated minerals decreased because of partial or complete collapse of the layers.The CES (KX/Ca1/2X) values of montmorillonites and micaceous vermiculites increased because of wedge site formation by partial collapse after heat treatment to 500 and 750°C in air. The CES values of coarse grained micas, however, decreased by dry heat treatment because of the collapse of frayed edges or wedge zones. Heated illites randomly interstratified with montmorillonite behaved like the specimen montmorillonites, while heated, well crystallized illites behaved similarly to the coarse grained micas. That the wedge zones are enormously selective for potassium was clearly proven here by the collapsed, heated minerals.The CES values of poorly crystalline illites interstratified with montmorillonite increased while those of well crystallized illites with discrete vermiculite impurity decreased upon hydrothermal treatment at 400°C and 500 bar (pressure). The decrease or increase in CES of the hydrothermally heated illite minerals can be explained by the loss or creation respectively of wedge zones just as in the case of air‐heated minerals.
Measurement of Apparent Electrical Conductivity of Soils by an Electromagnetic Induction Probe to Aid Salinity Surveys
Authors: de Jong E. , Ballantyne A. K. , Cameron D. R. , Read D. W. L. 
Published: July 2010

AbstractA noncontacting soil resistivity probe, based on electromagnetic induction, was used to measure soil salinity. Good correlations were obtained between the apparent bulk soil conductivity measured by the instrument and the electrical conductivity of saturated paste extracts or the bulk electrical conductivity measured by the Wenner four‐probe method. The electromagnetic induction technique provided less detailed information on salinity changes with depth than the other methods, but was faster and can provide a continuous record of salinity changes along a transect.
Ion Chromatographic Determination of Sulfate and Nitrate in Soils
Authors: Dick W. A. , Tabatabai M. A. 
Published: July 2010

AbstractA simple and precise ion chromatographic (IC) method for determination of SO42‐ and NO3‐ in soils is described. It involves determination of these anions in soil extracts by using a Dionex Model 10 Ion Chromatograph. An aliquot (≃2 ml) of soil extract is injected in the eluent stream (3.0mM NaHCO3 + 1.8mM Na2CO3), and the anions are separated by an analytical column containing Dionex low‐capacity anion‐exchange resin in the HCO3‐ form and converted to the corresponding acids by a suppressor column containing a strong acid cation‐exchange resin in the H+ form. Conductivity is used as the mode of detection. Results of SO42‐ and NO3‐ in soils by the IC method agreed closely with those obtained by the methylene blue and steam‐distillation methods, respectively. Tests indicated that S2‐, SO32‐, S2O32‐, S2O52‐, S4O62‐, SCN‐, thiourea, glucose‐6‐sulfate, and p‐nitrophenyl sulfate do not interfere in determination of SO42‐. Also, NO2‐ does not interfere in determination of NO3‐. This method gives quantitative recovery of SO4‐S and NO3‐N added to soils (5–50 µg/g soil). The detection limit is 1 µg SO4‐S or NO3‐N/g soil (0.2 µg SO4‐S or NO3‐N/ml of soil extract). With the IC method, SO4‐S and NO3‐N can be determined simultaneously in about 10 min.
Mineralization of Carbon and Phosphorus from Carbon‐14 and Phosphorus‐32 Labelled Plant Material Added to Soil
Authors: Dalal R. C. 
Published: July 2010

AbstractSoil receives a large amount of P annually through above and below ground plant materials and animal excretions. This P in these materials becomes available to the growing plants through microbial decomposition. Since P mineralization follows C mineralization (CO2 loss), both C loss and P mineralization (measured by the amount of P utilized by oats (Avena sativa L.) from the added roots and tops of 14C‐ and 82P‐labelled white clover (Trifolium repens L.) were assessed for 10 weeks in the controlled environment chambers (26°C/16°C, 12‐hour day/night temperature). By 10 weeks, 42 and 38% of applied P was utilized by oats from the roots and tops, respectively. During the same period, about 55 and 70% of the C was lost from the roots and tops, respectively, of the added plant material. The half‐lives, t1/2, of 82P utilization from the roots and tops were 10.8 and 12.4 weeks, respectively. The corresponding t1/2 of 14C mineralization were 15.3 and 8.1 weeks in the presence of plants and 15.2 and 9.7 weeks in the absence of plants.After the initial rapid loss of C, P mineralization followed C mineralization (or loss) of the added plant material closely. Since the decaying of roots and tops of crop plants and pastures in the field release P upon mineralization, this factor should be considered in soil P management practices.
The Effect of Roots on Soil Denitrification
Authors: Smith M. Scott , Tiedje James M. 
Published: July 2010

AbstractThe effects of plant roots on denitrification were studied using the acetylene inhibition method, both with short‐term anaerobic assays for potential denitrifying activity and with intact plants in soil. Experiments with anaerobic assays demonstrated that denitrification activity was greater in the rhizosphere of both pot and field grown plants. A split‐plate technique showed that potential denitrifying activity decreased rapidly in the first few millimeters away from roots. These effects were shown to be due, at least in part, to differences in available organic matter.A new method was developed for measuring short‐term denitrification rates of soils with intact plants in an aerobic atmosphere. The soil conditions in these assays were comparable to field conditions. When soil NO3‐ concentrations were high, the results confirmed prevailing opinion that denitrification rates are increased in the rhizosphere. In contrast, the planted soils denitrified at significantly lower rates than unplanted soils when NO3‐ concentrations were low. Thus, denitrification may sometimes be reduced in the rhizosphere. These experiments also indicated that increasing NO3‐ concentration increased the ratio N2O/(N2 + N2O), but that the roots had no consistent effect on this ratio.
Survival of Rhizobium in Soils Undergoing Drying
Authors: Pena‐Cabriales J. J. , Alexander M. 
Published: July 2010

AbstractStreptomycin‐resistant mutants of Rhizobium were used to study Rhizobium survival in soils undergoing drying. The decline in numbers of R. japonicum in soil was biphasic. The initial, rapid phase coincided with the time of major water loss, and the subsequent slow rate of decline of viability occurred as the soil lost little water. Similar population charges were found with other species of Rhizobium. The rate of dying of R. japonicum and R. leguminosarum during the second phase in soil at relatively low moisture levels was governed by the water content of the soil. In 10 days of drying, the cell numbers of the six Rhizobium species and a cowpea Rhizobium were reduced by two logarithmic orders of magnitude, and no differences in susceptibility were noted between the fast‐ and slow‐growing rhizobia. Exposure of R. japonicum to several cycles of wetting and drying resulted in a further reduction in population size with each cycle. The percentage survivors of R. japonicum was not greatly affected by the time required for the drying but was different in different soils. Rhizobia that proliferated in soil showed somewhat better survival than those grown in culture and added to soil. Decayed organic residues afforded little protection against desiccation, but placing the root‐nodule bacteria in a suspension of the polysaccharide they elaborate allowed for somewhat better survival.