bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Sulfur‐coated Urea Fertilizers on Merion Kentucky Bluegrass
Authors: Waddington D. V. , Turner T. R. 
Published: July 2010

AbstractSulfur‐coated urea (SCU) appears to be both agronomically and economically feasible for use as a slow‐release N source on turfgrasses. Because considerable variation can occur among SCU products, this study was conducted to evaluate six formulations that were representative of different coating weights and coating methods.Five experimental formulations from the Tennessee Valley Authority and Gold‐N, a product of Imperial Chemical Industries, were applied to ‘Merion’ Kentucky bluegrass (Poa pratensis L.) at a rate of 195 kg N/ha in the spring of 1974, 1975, and 1976. Coating weights of S on TVA materials had been varied to obtain laboratory 7‐day dissolution rates of 17, 26, and 35% from material coated with S only; and 16 and 26% from material coated with S plus a wax sealant. Gold‐N was coated with S plus a paraffin sealant and had a dissolution rate of 36%.Clipping weights and turf color were used to evaluate turfgrass response. With S‐only coatings, turfgrass response increased as coating weight decreased (dissolution rate increased). Differences due to coating weight were greatest in the first year, and diminished in the following years. In yield and color comparisons over three seasons, a low dissolution rate treatment never produced more response than a higher dissolution rate treatment. In comparison of materials with similar dissolution rates but with different coating methods, release of N was more rapid with a S plus wax coating than with a S‐only coating. The 7‐day dissolution rate was not dependable in predicting field response when coating method was varied.Plots were sampled for residual CSU in 1976, 1977, and 1978. After three growing season, residual SCU pellets ranged from 3 to 37% of the total applied weight; and after 2 additional years in which no fertilizer was applied, 0 to 13% remained. Variations in SCU formulation caused significant differences in turfgrass response to fertilization and in the amount of residual material; thus, factors such as coating weight and method should be known and taken into consideration when developing a fertilization program based on SCU.
Release of Urea by Granules of Sulfur‐Coated Urea
Authors: Jarrell W. M. , Boersma L. 
Published: July 2010

AbstractUrea diffuses through holes in the coatings of granules of sulfur‐coated urea (SCU) into the surrounding soil. The ability to predict the rate at which urea is released from SCU granules aids in matching the slow release characteristics of the fertilizer to specific climatic and soil conditions.When openings are small and the concentration of urea immediately outside each opening is very low, a two‐stage release pattern is proposed. During the initial stage, solid urea is dissolving and urea diffuses out of the granule at a constant rate. When all of the urea inside the granule has dissolved, the rate of release decreases logarithmically with time. The equations describing rates of release during the two stages are
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0001 for the constant rate period, and
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0002 for the falling rate period, where mr = m/Mo with m being the amount of urea released and Mo the amount of urea initially present in the granule, D is the diffusion coefficient, Ap is the cross sectional area of the pore through which diffusion occurs, Δxp is the length of the pore, ρ is the density of urea, and csat is the solubility of urea. The diffusion coefficient D and the solubility of urea csat are temperature‐dependent, according to
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0003 where T is absolute temperature and Tc is temperature in degrees centigrade.The temperature dependence of the release rate during the constant‐rate period as determined by experiment agreed well with that predicted from theory. These equations may be used to predict the rate of release provided the physical properties of the given SCU are known.
Particle Size Effects on Stockpiling and Spreading Agricultural Limestone
Authors: Alley M. M. , McCart G. D. , Wolf D. D. , Smith E. S. 
Published: July 2010

AbstractStockpiling of agricultural limestone is a necessity in many agricultural regions due to transportation and production limitations. Particle size influence on stockpiling and spreading ground limestone must be quantified in order to produce a material that is effective in neutralizing soil acidity and can be uniformly spread after weather‐exposed storage. Effects of particle size on bulk density, percent moisture, and spread pattern uniformity by a commercial twin‐spinner bulk spreader were measured. Calcitic and dolomitic limestones with >60% passing a 100‐mesh (150 µm) sieve bridged in the spreader body and resulted in uneven flow to the spreader spinners. Handling problems were not encountered with materials having <55% passing a 100‐mesh sieve. Ground limestones with particle size distributions of 85 to 88, 48 to 61, and 39 to 56% passing 20‐ (850 µm), 60‐ (250 µm), and 100‐mesh sieves, respectively, were evenly spread after outdoor storage. Bulk densities ranged from 1.34 to 1.53 g/cm3 while moisture contents varied from 0.7 to 6.0%.
Extractability of Phosphorus from Phosphate Minerals Common in Soils and Sediments
Authors: Williams J. D. H. , Mayer T. , Nriagu J. O. 
Published: July 2010

AbstractA four‐step fractionation scheme has been applied to a large suite of phosphate minerals common in soils and sediments. In general, most of the P contained in iron and aluminum minerals can be extracted by dithionite‐citrate‐bicarbonate (DCB) and/or NaOH treatment. Most of the P bound to apatites was liberated during digestion with 1.0N HCl solution. Thus the scheme provides a reasonable separation of Fe‐ and Al‐bound P from the P generally associated with apatites in soils. A large fraction of the P in fish bones was released by DCB reflecting the influence of the degree of crystallinity on the dissolution of the mineral phases. Crandallite (and related plumbogummite minerals), monazite, and xenotime were not extensively dissolved by the reagents employed in the fractionation procedure.
Spatial Variability of Nitrogen‐15 and Total Nitrogen in Some Virgin and Cultivated Soils
Authors: Broadbent F. E. , Rauschkolb R. S. , Lewis Kristine A. , Chang Grace Y. 
Published: July 2010

AbstractSoil cores were taken from six locations representing three virgin and three cultivated soils in increments of 15 or 30 cm down to depths ranging from 120 to 300 cm. The number of samples of an individual soil profile varied from 20 to 96, though smaller numbers of some subsurface horizons were obtained at two locations where very rocky conditions were encountered. Frequency distribution analysis of δ15N values and of total N showed that they were log‐normally distributed in about half the groups of samples. Assumption of normal distribution in all samples would result in a maximum error of 37% in total N and 0.1% in 15N content if the real distribution were in fact log‐normal. Coefficients of variation of total N were somewhat lower in cultivated soils than in virgin soils, but C.V. values for atom %15N were comparable in the two groups of soils. It is concluded that the magnitude of natural variation in δ15N values at a given sampling site, both laterally and vertically, is so great as to preclude tracing biological events by means of natural abundances.
Properties and Classification of an Eroded Soil in Southeastern Nebraska
Authors: Lewis D. T. , Witte D. A. 
Published: July 2010

AbstractPedons representing soil properties within three mapping units of the Wymore soil series were studied to determine if they were correctly classified and named. Present concept of the three units suggests that they differ in slope and/or erosion class, but that they are within the concept of fine, montmorillonitic, mesic Aquic Arquidolls. Pendons representing the noneroded, 0–2% slope unit (Wt) and the noneroded, 2–7% slope unit (WtC) exhibited properties that supported their present classification. However, 64% of the pedons sampled in the delineations representing the eroded, 2–7% slope unit (WtC2), and consequently the pedon representative of the WtC2 unit, had an epipedon that appeared to have been formed through tillage of a subsurface horizon. Established criteria for the mollic epipedon and the agrillic subsurface horizon were not evident. An ochric epipedon and cambic subsurface horizon existed in this pedon. These features plus a high base saturation, lack of pedogenic lime and mottling in the solum supported placement of the pedon representative of the WtC2 unit in the subgroup Aquic Dystric Eutrochrept. This pedon is representative of > 45,000 ha in the region of its existence.
The Penetration Resistance in a Soil with Well‐defined Structural Units
Authors: Bradford J. M 
Published: July 2010

AbstractBased on both laboratory and in situ probe penetration tests within each horizon of a soil with well‐defined structural units, the magnitude and variability of probe resistance values in relation to probe diameter and structural features are presented. Total penetration resistance was equal for 0.376‐ and 0.514 cm‐diam 60° angle probes; however, the resistance standard deviation and coefficient of variation were larger for the smaller probe. A pocket penetrometer gave significantly larger penetration resistances. There was a close relationship between probe penetration resistance of a 0.376‐cm‐diam probe and root length in natural B3 horizon.
Amorphous Material and Aluminum Interlayers in Quebec Spodosols
Authors: De Kimpe C. R. , Laverdiere M. R. 
Published: July 2010

AbstractClay fraction from spodic B horizons of Appalachian and Laurentian soils was recovered after organic matter and sesquioxides removal. Sodium citrate and sodium hydroxide further extracted various amounts of Al, Si, and Fe. Samples from the Appalachian sites released < 5% Al2O3 + SiO2 and < 1% Fe2O3. There were only small differences between the amounts of material extracted by both reagents. After citrate treatment, a moderate increase of CEC was observed and related to Al interlayer removal, while after NaOH + citrate treatment the CEC decreased slightly because of amorphous material removal. Samples from the Laurentian sites released from 9.3 to 30.0% Al2O3 + SiO2 in NaOH and subsequently 1.6 to 6.0% Fe2O3 in Na‐citrate. The presence of large amounts of amorphous material prevented the identification of clay minerals by X‐ray diffraction analysis, and its removal caused a strong decrease of the CEC. Citrate alone extracted this poorly crystalline material at a slower rate and for these samples, this was followed by a decrease of the cation exchange capacity.
Activities of Cu2+ and Cd2+ in Soil Solutions as Affected by pH
Authors: Cavallaro N. , McBride M. B. 
Published: July 2010

AbstractThe concentrations of free copper and cadmium ions in soil suspensions were measured by an ion‐selective electrode as a function of pH after equilibrating metal salt solutions with the soils. Similar experiments were done with water‐extractable organic matter. Free (uncomplexed) Cu2+ concentrations were strongly pH‐dependent in the soil systems, but well below the level where precipitation could have occurred. Free Cd2+ concentrations were much less affected by pH adjustment, and the nonacid soil systems approached saturation or oversaturation with respect to CdCO3 precipitation at high pH. Similiar dependence of the free metal ion concentration on pH was found in water extracted organic matter solutions. Precipitation of CdCO3 in oversaturated solutions containing the extracted organic matter was slow, while none of the copper‐organic matter solutions attained oversaturation with respect to Cu(OH)2 or Cu2(OH)2CO3.
The Effect of Nitrate on Nitrous Oxide Reduction in Organic Soils and Sediments
Authors: Terry Richard E. , Tate Robert L. 
Published: July 2010

AbstractInhibition of N2O reduction by NO3‐ in cultivated Pahokee muck was determined by measuring N2O accumulation in soil samples incubated in the presence and absence of acetylene. At NO3‐‐N levels of 40 mg/liter or greater, nearly 100% of the gaseous denitrification products were N2O in Pahokee muck. Reduction of the accumulated N2O proceeded rapidly after the NO3‐ was exhausted from the soil. In comparison, N2O was readily reduced in ditch sediment samples in the presence of comparable concentrations of NO3‐. With NO3‐‐N concentrations in the ditch sediments ranging from 90 to 39 mg/liter, < 10% of the gaseous denitrification products were N2O. Similarly, NO3‐ levels in soil samples from a vegetable field which had been flooded 22 days had negligible effect on N2O reduction. These data demonstrate that the inhibitory effect of NO3‐ on N2O reduction was less in sediments and in organic soils that had been subjected to prolonged flooding than in the cultivated soils.
Enzymatic Activities in Coniferous Leaf Litter
Authors: Spalding Brian P. 
Published: July 2010

AbstractAssays for measuring the activities of cellulase, xylanase, mannase, amylase, β‐glucosidase, invertase, and protease employing buffered suspensions of ground coniferous and deciduous leaf litter exhibited zero‐order kinetics. Only a small percentage of the whole‐litter activities of invertase (3%), β‐glucosidase (3%), and protease (1%) were extractable into 0.05M potassium acetate, pH 5.0; however, extractable activities of cellulase and xylanase represented from 39 to 174% of the whole‐litter activities indicating their soluble exocellular nature. Extractable protease and amylase activities were best correlated (r=0.65 and 0.65, respectively) with the average daily rates of CO2 evolution in a group of 90 leaf litter samples equally representing 18 coniferous species. Enzymatic activities were readily detectable in extracts of all samples but classification of the samples by species provided little differentiation in the distribution of either enzymatic activities or rates of CO2 evolution. Mannase, cellulase, and xylanase activities were well‐correlated with each other (r=0.88) in all samples. Assays at‐tempting to measure a pool of readily‐metabolizable substances in litter by extractable reducing substances, ninhydrin‐positive substances, glucose, and phenolics failed to show correlation coefficients > 0.41 with rates of CO2 evolution. Addition of D‐(+)‐catechin to litter extracts, up to levels equivalent to those observed in the group of samples, did not inhibit any carbohydrase thus suggesting the lack of inhibition of litter‐decomposing enzymes by the concentrations of phenolics present in these coniferous leaf litters.
Use of Soil Survey Data in a Model for Simulating Regional Soil Moisture Regimes
Authors: Bouma J. , de Laat P. J. M. , Awater R. H. C. M. , van Heesen H. C. , van Holst A. F. , van de Nes Th.J. 
Published: July 2010

AbstractDepth to water table and evapotranspiration rates were simulated with the computer program GELGAM for an area of 6 by 6 km, which was described by square nodal areas of 25 ha each in a grid with a mesh width of 500 m. Soils which occupied the largest part within a nodal area (as determined by analyzing a soil map) were considered representative for the nodal area and were characterized by basic data in terms of rooting depth, moisture retention curves and hydraulic conductivity curves. Four simulation runs were made with GELGAM, using increasingly detailed and costly basic data obtained by estimates and measurements in four phases as follows: (i) identical estimates for all nodal areas; (ii) estimates based on an existing soil map; (iii) estimates from one on‐site boring per nodal area, and (iv) measurements of physical data.Estimates of physical data were based on extrapolation of data obtained for similar soil horizons elsewhere, using empirical relationships with soil texture, organic matter content, and bulk density. Such estimates, when based on descriptions of mapping units in the soil survey report, were good for surface horizons but poor for the deeper subsoil beyond the solum in the region of the fluctuating water table. Simulated depth to water table agreed well with measured depths in all phases, but only when using measured physical data for the deeper subsoil. Simulated evapotranspiration using phase 1 data produced poor results for individual nodal areas when compared with phase 4 data (reference level), while phase 2 data produced good results if measured physical data for the deeper subsoil were included. Physical variability of nodal areas was better characterized by the soil survey data than by results from a single boring (phase 3).Use of existing soil survey data, in combination with selected on‐site investigations, could reduce the cost of data gathering in this study by an estimated 50% as compared with the common procedure of making systematic borings in each grid point. The degree of detail of interpretation of simulation results for nodal areas should be limited by the field variability observed.
A Scanning Electron Microscopy Evaluation of the Fabric and Mineralogy of Some Soils from Malaysia
Authors: Eswaran H. , Daud N. 
Published: July 2010

AbstractFour pedons — an Aquic Dystropept, Typic Paleudult, Tropeptic Haplorthox, and Haplic Acrorthox — representing a sequence of soils on shales in Peninsular Malaysia were employed to evaluate the changes in plasmic fabric and related distribution patterns as a function of soil genesis. The decreases in sepic features when proceeding from the cambic to the oxic stage of soil formation is due to changes in colloid composition (micaceous to kaolinite‐sesquioxide), size of colloid (coarse to fine clay), and masking of the optical properties of the plasma by the free Fe. Complimentary SEM studies are presented to show the structure of the domains and the interdomain relationships which determine the plasmic fabrics and the related distribution patterns.Scanning electron microscopy (SEM) and thin‐section micrographs of secondary goethite and gibbsite are presented and based on the SEM morphologies, a silicification of the gibbsite to kaolinite is postulated in the surface horizons of the Acrorthox.
The Priming Effect on Rate of Tobacco Mosaic Virus Degradation in Soil Columns
Authors: Cheo P. C. , Nickoloff Jon A. 
Published: July 2010

AbstractSoil columns were set up to monitor tobacco mosaic virus (TMV) degradation in a time sequence study. One set of columns received a constant input of virus for nearly 3 months (challenged columns) and an additional set of soil columns received only a single treatment of virus (fresh columns). Gradual degradation of TMV in the challenged columns netted negligible residual virus at the end of the challenging period, even though a total of 11.75 mg of TMV had been added. When a high titer of virus was introduced into both columns for comparison, a much faster rate of virus degradation occurred in the challenged columns, especially in the early stages. In fresh columns the rate of virus degradation was sluggish at the early stage but accelerated after 2 weeks. Therefore, repeated additions of a small amount of TMV stimulated the process of TMV degradation in soil. The rate of TMV degradation was comparatively higher in the upper (0–10 cm) layers of the soil column than the lower (10–20 cm) layers.
Nitrate Movement with Zero‐order Denitrification in a Soil Profile
Authors: Kanwar R. S. , Baker J. L. , Johnson H. P. , Kirkham D. 
Published: July 2010

AbstractA theoretical analysis of the movement of nitrates in an unsaturated soil with zero‐order denitrification is presented. The transport equation and boundary conditions are established to represent a field situation (i.e., application of N to the surface of a soil that already has nitrogen present in its profile). An analytical solution is derived. For given values of the diffusivity, pore solute velocity, and the rate coefficients for denitrification, the relative concentration profiles are shown at different times. Comparison with published data is made and it seems that the theoretical relationship fits the data reasonably well.
Sodium/Calcium Exchange in Montmorillonite and Illite Suspensions
Authors: Shainberg I. , Oster J. D. , Wood J. D. 
Published: July 2010

AbstractThe effect of salt concentration and exchanger composition on Na/Ca exchange in montmorillonite and illite suspensions (0.02 to 0.08 g clay/g water) was studied, where the equivalent fraction of exchangeable Ca, ECa, ranged from 0.6 to 1. A theoretical evaluation based on double‐layer theory for montmorillonite indicates that the formation of tactoids and internal surfaces at the Ca3+ end of the exchange isotherm can cause the Vanselow selectivity coefficient, KV, to depend on exchangeable cation composition and total electrolyte concentration. Whereas for montmorillonite, KV increased with ECa (0.6 < ECa < 1), as predicted for internal surfaces, the reverse was true for illite, where external surfaces predominate. Likewise, for a given Na adsorption ratio, dilution of the equilibrium solution for illite (0.6 < ECa < 1) and for montmorillonite (ECa ≃ 0.6) decreased KV as predicted for external surfaces.The average Gapon selectivity coefficient for the montmorillonite (0.011) and illite clays (0.023) with ECa ≤ 0.8, suggests that the value for soils, (0.0148) reflects their mixed mineralogy.
Exchangeable Aluminum and pH as Indicators of Lime Requirement for Corn
Authors: Farina M. P. W. , Sumner M. E. , Plank C. O. , Letzsch W. S. 
Published: July 2010

AbstractNotwithstanding a voluminous body of literature on the subject there is still poor agreement regarding the relative merits of lime requirement indices based on exchangeable Al and those based on pH measurements. The work reported here was conducted in an effort to obtain greater clarity on the subject. Lime × P × Mg factorialized pot experiments were conducted on Mollisols, Ultisols, and Oxisols using corn as an indicator crop. Plant tissue was analyzed for several essential elements plus Al and the soils were tested for exchangeable cations, P, and pH. Yield responses fell into three categories: (i) those in which liming neither promoted nor depressed growth, (ii) those where growth was initially promoted by liming with no depressive effect and (iii) those where liming to neutral pH values depressed yield. The results showed that corn response to lime was essentially similar over a wide range of soils when Al saturation of the soil was used as the index of lime requirement. Corn response was poorly related to pH in water but the relationship improved when salt pH was used. As nearneutral pH values were approached, the uptake of a number of nutrients was reduced, suggesting that the long‐held view that such pH values have beneficial effects on nutrient availability warrants re‐investigation.