bluuebunny/crossref_metadata_2025_split huggingface dataset:
Problems in Direct Steam Distillation of Soil for Mineral Nitrogen Determination Due to Carbonates
Authors: Clausen C. R. , Russelle M. P. , Flowerday A. D. , Olson R. A. 
Published: July 2010

AbstractA follow‐up study to one on Mg2+ interference in NO3‐ measurement by direct steam distillation of soil revealed an added problem of low recovery with the method when used on calcareous soils. The CO32‐ ion was presumed responsible, prompting the current investigation on the effect of soil CO32‐ and Mg2+ levels on NH4+ and NO3‐ determination by the method.Four series of CO32‐ amendments to distillation flasks were made to simulate soil levels of (i) low solubility CO32‐ [CaCO3 and 3 MgCO3·Mg(OH)2], (ii) soluble CO32‐ (K2CO3), (iii) Mg2+ and soluble CO32‐ combinations, and (iv) soluble CO32‐ in a Mg2+‐free system. All received 40 ppm N as NH4NO3 with NH4+ and NO3‐ measured by prescribed distillation procedures. The results show that Mg2+ and CO32‐ Independently suppress recovery of NO3‐ and Interact to interfere with both NH4+ and NO3‐ determination in direct distillation of calcareous soils.
Determination of Sorptivity based on In‐situ Soil Water Redistribution Measurements
Authors: Chong S. K. , Green R. E. , Ahuja L. R. 
Published: July 2010

AbstractA simple, physically based algebraic equation is derived for calculating sorptivity as a function of antecedent soil water content. The wetting front matric pressure head, Hf, determined from the field profile redistribution data in a previous study, is utilized in an equation which gives sorptivity, S, as a function of fillable porosity, i.e., the difference between the satiated and antecedent soil water content, (θs − θi), satiated hydraulic conductivity, Ks, and wetting front matric pressure head, Hf, namely, S2 = −2(θs − θi)KsHf. The final equation gives S explicitly as a function of antecedent water content, θi, with θs and Ks being constants for a given soil. The calculated sorptivity is assessed by its use in the Talsma‐Parlange infiltration equation and subsequent comparison of predicted and measured infiltration. The method was tested on seven different sites with 14 infiltration measurements on Oxisol soils of Hawaii. The percentage error between predicted and measured cumulative infiltration ranged from 2.1% to 51.9%, with an average error of 21.8% for the 14 comparisons.
Infiltration Prediction based on Estimation of Green‐Ampt Wetting Front Pressure Head from Measurements of Soil Water Redistribution
Authors: Chong S. K. , Green R. E. , Ahuja L. R. 
Published: July 2010

AbstractA simple, physically based algebraic equation was derived to calculate the wetting front matric pressure head, Hf, in the Green‐Ampt equation of infiltration. The derivation of the equation involved combining the simple hydraulic conductivity function with the wetting front matric pressure head function proposed by R. G. Mein and C. L. Larson (1971). The parameters in the derived equation were determined from fitting a power function to the experimental data of soil water content and soil water pressure head vs. elapsed time obtained during the post‐infiltration redistribution period. In the derived equation, Hf is expressed as a function of antecedent soil water content. At low initial water contents, the equation shows that Hf is essentially a constant. Evaluation of the calculated Hf values was accomplished by utilizing Hf in the Green‐Ampt equation to predict infiltration at seven field sites for soils at initial water contents below field capacity. Predicted cumulative infiltration was compared with infiltration measured with a double‐ring infiltrometer. The resulting Green‐Ampt predictions were accurate for initially dry soils, with a correlation value of r = 0.94 and a relative error of 12.1%.
Dissolution Rate of EDTA‐extractable Phosphate from Soils
Authors: Onken A. B. , Matheson R. L. 
Published: July 2010

AbstractThe kinetics of phosphorus (P) dissolution in EDTA (ethylenedi‐aminetetraacetic acid) solution were investigated for several soils for the purpose of determining if the dissolution rate constants could be related to crop response to applied P. Eight kinetic models were evaluated using coefficients of determination (R2) and standard errors of estimate (SE). Additionally, the effects of temperature and soil‐solution ratio on P dissolution in the EDTA solution were determined.Relatively high values of R2 and low values of SE indicated that P dissolution in EDTA solution for the soils used was most often best described by the two‐constant rate equation, the Elovich‐type equation, and the differential rate equation. None of the models best described the dissolution for all soils. Using R2 and SE for evaluation, the best relationships found between dissolution rate constants and yield response to applied P were for the two‐constant rate equation (R2 = 0.97; SE = 2.58) and the differential rate equation (R2 = 0.95; SE = 2.69). Soil‐solution ratio affected the values of dissolution rate constants, with those obtained from the differential rate equation most sensitive. The Arrhenius equation described reasonably well the effect of temperature on values of the dissolution rate constants.
Transformations of Amide Nitrogen in Soils
Authors: Frankenberger W. T. , Tabatabai M. A. 
Published: July 2010

AbstractAmides added to soils are hydrolyzed to ammonium (NH+4) and their corresponding carboxylic acids. Studies of transformations of amide‐N in soils deserve attention because amides have potential as nitrogen (N) fertilizers. In this work, the transformations of amide‐N (200 µg/g of soil) were studied in field‐moist soils incubated under aerobic conditions at 30°C for 14 days. The recovery of inorganic N (as NH3, NH4+, NO2‐, and NO3‐) produced from 25 amides or their derivatives was determined and compared with those obtained with (NH4)2SO4 and urea added to five soils. Results showed that with the exception of cyanamide, dicyandiamide, benzenesulfonamide, and sulfanilamide, which resisted decomposition, all other amides were readily hydrolyzed in the five soils used. With most of the amides studied, the inorganic N produced was accumulated as NO3‐. The recovery of nitrogen as NO3‐ from each of five soils treated with urea, acetamide, propionamide, 2‐cyanoacetamide, n‐butyramide, oxamide, or DL‐lactamide was <50% of the N added. The average percentage of NH4+‐N recovered from the soils used exceeded 40% of the total inorganic N produced when thioacetamide, fluoroacetamide, and 2‐chloroacetamide were added to soils. With one sandy soil, the addition of urea, formamide, N‐benzylformamide, and p‐nitrobenzamide resulted in accumulation of NO2‐, ranging from 5 to 21% of the inorganic N recovered. Appreciable amounts of NH3 were volatilized when formamide, acrylamide, 2‐cyanoacetamide, p‐nitrobenzamide, and urea were applied to soils, especially from the sandy soil. The average recovery of amide‐N as inorganic N from the five soils used ranged from 4% with dicyandiamide to 100% with formamide.
Adsorption and Reduction in Bioactivity of Polychlorinated Biphenyl (Aroclor 1254) to Redroot Pigweed by Soil Organic Matter and Montmorillonite Clay
Authors: Strek H. J. , Weber J. B. 
Published: July 2010

AbstractAroclor 1254 polychlorinated biphenyl (PCB) applied to untreated (1.4% organic matter) and H2O2‐treated (0.2% organic matter) Lakeland sand at rates of 0, 50, 100, 150, and 200 ppm caused significant reductions in redroot pigweed (Amaranthus retroflexus L.) growth at the high rates of application. Polychlorinated biphenyl decreased plant height in the H2O2‐treated soil much more than in the untreated soil. A greater decrease in dry weight also resulted in the H2O2‐treated soil, but only at the 200 ppm rate. In one study, soil was amended with montmorillonite clay and organic matter (peaty muck) at rates of 0, 2.5, 5.0, and 10.0% by weight and treated with 200 ppm PCB. The organic matter proved to be much more effective than montmorillonite in reducing PCB toxicity to pigweed at the lower rates of addition (2.5 and 5.0%), but no differences were noted between the two adsorbents at the 10% rate. Adsorption of 14C‐labeled PCB closely resembling Aroclor 1254 by the untreated and H2O2‐treated soils, montmorillonite clay, organic matter, and activated carbon was measured. The order of highest to lowest adsorption was as follows: activated carbon ≫ organic matter > montmorillonite clay > Lakeland sand > H2O2‐treated Lakeland sand. These experiments suggest that organic matter content of a soil, and clay content to a lesser extent, are involved in reducing the availability of soil‐applied PCB to pigweed. Differences in reduction of PCB toxicity to pigweed are explained by differences in adsorption by the adsorbents.
Phosphate Rock Dissolution and Availability in Cerrado Soils as Affected by Phosphorus Sorption Capacity
Authors: Smyth T. J. , Sanchez P. A. 
Published: July 2010

AbstractThe reactivities of two phosphate rocks (PR), North Carolina and Patos de Minas, were compared in seven acid soils from the Cerrado of Brazil during 158 days of laboratory incubation. Four soils are classified as Typic Acrustox and the remaining three Typic Haplustox, Aeric Tropaquept, and Ustoxic Quartzipsamment. Dissolution was accompanied by measurements of resin‐ and Olsen‐extractable P and exchangeable Ca. North Carolina PR was more reactive than Patos de Minas PR. Changes in Olsen‐P were more indicative of the PR dissolution process than resin‐P. Maximum PR reactivity, as measured by increases in calcium, occurred in those soils maintaining the lowest amounts of Olsen‐extractable P. Such soils have the highest clay and free Fe2O3 contents and, consequently, the highest P sorption capacities. Maintenance of low levels of solution P is considered an important driving force for PR dissolution in these acid soils. Consequently, high P sorption capacity favored the dissolution of PR in such soils. The “i” modifier in the Fertility Capability Classification system separated those soils in which phosphate rocks reacted rapidly from those that reacted at a slow rate.
Clay Minerals in Northern Plains Coal Overburden as Measured by X‐ray Diffraction
Authors: Klages M. G. , Hopper R. W. 
Published: July 2010

AbstractMathematical models were tested for changing x‐ray diffraction data to percentages of clay minerals in coal overburden. Various factors for adjusting peak areas were tested on 50 eastern Montana samples that contained smectite, illite, and kaolinite, with lesser amounts of other minerals. Cation exchange capacities (CEC) of the clays were estimated from the calculated mineral percentages and correlated against measured CEC. The best model gave an r2 of 0.89. It was used for estimating clay mineralogy at six mine sites in the Northern Great Plains. Average mineral contents in the surface 8 to 38 m of five of seven drill holes in the Montana‐Wyoming border area were 40% smectite, with 20% each of illite and kaolinite. Clays from greater depths in the same area had no smectite and an average of 50% each of illite and kaolinite. All samples from a mine in central North Dakota were high in swelling clay, with an average of 60% smectite and 10% vermiculite. Samples from four holes at a mine in eastern Wyoming were all high in kaolinite, having an average of 50% with 30% illite and 10% interstratified smectite‐vermiculite.
Diffusion of Potassium, Calcium, and Magnesium in Bozeman Silt Loam as Influenced by Temperature and Moisture
Authors: Schaff B. E. , Skogley E. O. 
Published: July 2010

AbstractA laboratory experiment was conducted to study the influence of temperature and moisture on the diffusion of potassium (K), calcium (Ca), and magnesium (Mg) to an H‐saturated resin sink in Bozeman silt loam with bulk density of 1.45 g/cm3. Diffusion of K and Ca to the resin sink was significantly (P < 0.005) influenced by temperature (5, 15, and 30°C), but that of Mg was not. Soil moisture (10, 17, and 28%) significantly (P < 0.005) influenced the diffusion of all three cations. The temperature by soil moisture interaction was significant for all three cations. The concentrations of extractable K, Ca, and Mg in four concentric soil layers, each about 1 mm in thickness, around the resin sink also were measured during the 96‐hour diffusion period. The concentration of each cation in each layer was significantly influenced by temperature and moisture.
Availability and Extractability of Phosphorus from Soils Having High Residual Phosphorus
Authors: Adepoju A. Y. , Pratt P. F. , Mattigod S. V. 
Published: July 2010

AbstractSurface soil materials from the 0‐ to 15‐cm depth of 12 sites were cropped in the greenhouse to determine quantities of phosphorus (P) removed in harvested forage and to correlate chemical soil tests with P removal by crops. Soil samples taken before and after cropping were analyzed for P extracted by NaHCO3 and by an anion‐exchange resin (AER). Quantities of P extracted by NaHCO3 and by AER before cropping were significantly correlated with total P removed by cropping, with the NaHCO3‐extracted P producing the higher correlation coefficients. However, in terms of relationships of P removed by cropping with extractable P, the soils separated into two groups. The first group, characterized by relatively high ratios of P removal in crops to extractable P, particularly for soil samples taken after cropping, tended to have relatively high pH, high soluble Ca, and clayey textures. The second group, having lower ratios of P removal to extractable P, tended to have neutral pH values and relatively low soluble Ca and sandy textures. The data suggest that the estimation of quantities of available P from soil analysis might be highly dependent on soil characteristics and the nature of the P compounds that have accumulated.
A Theoretical Study of the Inclusion of Dispersion in Boundary Conditions and Transport Equations for Zero‐order Kinetics
Authors: Parlange J.‐Y. , Starr J. L. , Barry D. A. , Braddock R. D. 
Published: July 2010

AbstractThe transport of a solute in a soil column is considered for zero‐order kinetics. The visible displacement of the solute is affected by dispersion. The dispersion coefficient enters both the transport equation and the boundary condition. It is shown that the latter is the most important effect and a simple equation is proposed to describe solute transport, which takes into account the influence of dispersion in the boundary condition, but not in the transport equation. Validity and limitations of this equation are discussed in some detail by comparison with the complex but exact solution for zero‐order kinetics.
Substitution of Ammonium and Potassium for Added Calcium in Reduction of Ammonia Loss from Surface‐applied Urea
Authors: Fenn L. B. , Matocha J. E. , Wu E. 
Published: July 2010

AbstractAmmonia (NH3) volatilization loss from surface application of urea must be reduced if urea is to gain further acceptance for use in pastures and on other non‐ or low‐tillage systems which do not permit soil incorporation. The method used to reduce NH3 loss should not increase costs of the N fertilizer significantly. Preferably, the material used should itself be a fertilizer nutrient.The nitrate salts of the monovalent cations NH+4, K+, and Na+ were tested as substitutes for chloride or nitrate salts of Ca2+ to depress NH3 losses when mixed with surface‐applied urea. Ammonia losses were measured from soils with different cation exchange capacities (CEC) in the laboratory, with residual N quantified by growing sudangrass on the variously treated soils under greenhouse conditions.Laboratory and/or greenhouse data indicate that NH3 loss from surface‐applied urea was most effectively reduced by Ca salts. Substitution of K, Na, and NH4 salts for Ca salts was increasingly effective as soil CEC increased. Monovalent salts were effective in reducing NH3 losses if the soil had exchangeable Ca2+ + Mg2+. In sand, however, monovalent salts did not reduce NH3 losses. The order of effectiveness on nonsandy soils was Na+ = K+ > NH+4 in reducing NH3 loss.Potassium as KNO3 or KCl can be used effectively to partially replace (Ca + Mg) nitrate or chloride salts with urea to reduce NH3 losses. Ammonium nitrate was ineffective in reducing NH3 losses except where high N application rates were used or where little or no soil CEC existed. The efficacy of NH4NO3 seemed to be due to its acidic nature more than displacement of exchangeable Ca2+ + Mg2+.
Field Vs. Laboratory Determined Hydraulic Conductivities of Some Slowly Permeable Horizons
Authors: Watts F. C. , Huckle H. F. , Paetzold R. F. 
Published: July 2010

AbstractSaturated hydraulic conductivities K(µm/s) of soils of spodic and argillic horizons were measured in several Florida soils. The soils were Haplaquods, Haplohumods, Glossaqualfs, and Argiaquolls. Two methods of measurement were compared. The core method consistently gave larger hydraulic conductivity values than the piezometer method. The lowest K(µm/s) rates were in argillic horizons. The permeability classification of most soils studied depended upon the measurement method used.
Salt Status of Glacial Till Soils of North‐Central Montana as Affected by the Crop‐Fallow System of Dryland Farming
Authors: Ferguson Hayden , Bateridge Tom 
Published: July 2010

AbstractPaired samples from adjacent dry‐farmed and native grassland areas of glacial till soils of north‐central Montana were analyzed for soluble salts to determine if crop‐fallow farming has caused increased salt leaching. The results indicate that approximately 50 years of crop‐fallow farming has significantly reduced the soluble salt content of some soils. From an edaphological standpoint the salt reduction in the root zone is beneficial. However, up to 90 t/ha of salt have been moved in the soil toward (to) the groundwater table; this is the source of the salts causing groundwater salinization and saline seeps.
Perched Water Tables on Hillsides in Western Oregon: II. Preferential Downslope Movement of Water and Anions
Authors: Hammermeister D. P. , Kling G. F. , Vomocil J. A. 
Published: July 2010

AbstractPerched water tables on hillsides in western Oregon potentially provide a means by which pollutants from agricultural and domestic sources may enter surface waters and consequently degrade the quality of these waters. This paper reports the results of experiments which were carried out to investigate the flow of solutes and water from buried line sources in and above perched water tables on three different hillsides in western Oregon. In the saturated soil and rock mantles of two hillsides, evidence suggests that water and solutes flow preferentially through large continuous voids. The evidence includes the very high maximun rate of anion movement downslope, the failure of pore velocities calculated from Darcy's Law to predict the rate and direction of anion movement, the short time before high levels of anions are detected downslope, and the spatial variability in the maximum rates of anion movement over the depth and width of sites. On the third hillside, tracer anion movement and soil water pressure measurements indicate that preferential flow occurs through large continuous pores during heavy rainfall while the surrounding soil and rock mantle remains unsaturated. Finally, experiments with Rodamine WT dye show that a variety of continuous voids of different origins and sizes conduct water and solutes preferentially in the soil and upper regions of rock on these hillsides.
Identification of Ferrihydrite in Soils by Dissolution Kinetics, Differential X‐ray Diffraction, and Mössbauer Spectroscopy
Authors: Schwertmann U. , Schulze D. G. , Murad E. 
Published: July 2010

AbstractFerrihydrite is a poorly crystalline, natural Fe3+ oxide which occurs in ochreous spring precipitates and hydromorphic soils of humid temperate climates. The identification of ferrihydrite in soils is complicated by its association with goethite, quartz, and layer silicates.The following criteria were used to identify ferrihydrite in Fe‐oxide accumulations from soils: high solubility in acid oxalate, five to six broad x‐ray diffraction lines, and the existence of a typical magnetic hyperfine field distribution at 4K in Mössbauer spectra rather than a discrete field value. Identification of low concentrations of ferrihydrite (≲ 20% oxalate‐soluble Fe) by x‐ray diffraction was made possible by subtracting diffraction data obtained after oxalate treatment from data obtained before such a treatment (differential XRD). Oxalate treatment preferentially dissolves ferrihydrite over goethite. This led to an increase in the quadrupole splitting observed in Mössbauer spectra from ∼0.10 to ∼0.23 mm s−1, resulted in a significantly narrower field distribution, and intensified the goethite DTA peak.
Construction of Soil Thermocouples for the Novice
Authors: Culik M. N. , Doran J. W. , Richards K. A. 
Published: July 2010

AbstractSoil temperatures affect the physical, chemical, and biological properties of most soils. Consequently, measurement of soil temperatures is important to understanding the effects of management practices that alter soil temperatures on the soil ecosystem. Thermocouples are often used for measurement of soil temperature where large amounts of data are collected and the use of other temperature‐sensing devices is either too expensive or impractical. However, information on the construction and design of soil thermocouples is often difficult to assemble. Procedures and recommendations are given in this note which will aid the novice in assembling materials, constructing, and connecting thermocouples for measurement of soil temperatures.
Characterization of Copper Availability and Corn Seedling Growth by a DTPA Soil Test
Authors: Dragun James , Baker Dale E. 
Published: July 2010

AbstractA greenhouse experiment was conducted to determine (i) the physical and/or chemical properties of soils which control Cu availability; (ii) if 0.0004M DTPA (diethylenetriaminepentaacetic acid) effects a small exchange of Cu in soils; and (iii) if pCu, estimated by iterative computer calculations based on DTPA stability constants, reflects the availability of Cu in soils. The growth and Cu accumulation of corn seedlings were studied using 16 northeastern United States soils, each treated to contain 125, 250, and 500 ppm total Cu. Soil pH, percent organic matter, cation exchange capacity (CEC), percent clay, percent silt, percent sand, percent Na2O, and DTPA‐extractable Cu were measured in order to relate soil properties to Cu availability and seedling growth.The soil factors affecting the mean soil Cu activity coefficient and therefore controlling Cu availability were pH and the silt fractions of Na‐bearing minerals. The DTPA at 0.0004M with a 1:10 soil‐to‐solution ratio did not effect a small exchange for Cu. For most soils, the DTPA extracted the labile Cu. Finally, when medium and fine‐textured soils are tested by the Baker DTPA soil test, resulting pCu values of approximately 11.9 and less should in general indicate high soil Cu availability (i.e., soil Cu availability ≧ 0.16 ppm) and reduced corn growth.