bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Fertilizer Source on Denitrification and Nitrous Oxide Emissions in a Maize‐field
Authors: Duxbury J. M. , McConnaughey P. K. 
Published: July 2010

AbstractThe C2H2‐block method was used to measure denitrification in a maize (Zea mays L.) field over the 85‐d period between sidedressing with N fertilizer and harvest. Measurement locations were changed weekly in order to avoid problems associated with microbial utilization of C2H2 and inhibition of nitrification. Nitrous oxide (N2O) fluxes were measured both with and without C2H2 addition to soil. Without C2H2 addition to soil, 0.3 kg N ha−1 was evolved from both unfertilized and Ca(NO3)2 treated soil, whereas 2.5 kg N ha−1 was evolved from urea treated soil. This difference was attributed to formation of N2O during nitrification of NH+4 liberated from urea. With C2H2 addition to soil, 1.6, 2.0, and 2.4 kg N ha−1 were evolved as the result of denitrification in the zero N, Ca(NO3)2, and urea treated sites, respectively. Total gaseous N loss from a particular N treatment was approximated by adding together the N2O‐N loss with and without C2H2 addition to soil. The gaseous N loss associated with fertilizer addition was <3% of that applied. The ratio of N2/N2O evolved without C2H2 addition to soil was estimated to be in the range of 4:1 to 7:1 for the zero N and Ca(NO3)2 treatments and about 1:1 for the urea treatment. Denitrification was responsible for at least 80% of the measured gaseous N loss from the zero N and Ca(NO3)2 treatments. About equal amounts of gaseous N loss from the urea treatment occurred via denitrification and during nitrification of liberated NH+4.
Profile Modification and Irrigation Effects on Yield and Water Use of Wheat
Authors: Eck Harold V. 
Published: July 2010

AbstractWhere water is limited, there are continuous searches for management practices that increase water use efficiency (WUE). Profile modification (PM) of Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls) has been shown to increase yield and WUE of grain sorghum [Sorghum bicolor (L.) Moench] and alfalfa (Medicago sativa L.). We hypothesized that it might increase those of winter wheat (Triticum aestivum L.) and, combined with limited irrigation, might further increase water use efficiency. A 4‐yr study was conducted on a site on which PM treatments (imposed in 1964) included thorough mixing of the soil profile to 0, 0.9, and 1.5 m with a wheel‐type ditching machine. Measurements in 1985 showed that PM still affected infiltration rate, bulk density, and surface elevation of the soil. Irrigation treatments were: (i) fall irrigation only (preplant or preplant + emergence), (ii) fall irrigation plus one spring irrigation, (iii) fall irrigation plus two spring irrigations, and (iv) fall irrigation plus three spring irrigations. Under irrigation Treatment I, compared to yields on unmodified soil, average grain yields were increased 11% by 0.9‐m PM and 20% by 1.5‐m PM. With Treatment II, average increases were 16 and 25%, respectively, but under treatments III and IV, PM did not affect grain yields. Under irrigation Treatment I, compared to WUE on unmodified soil, WUE for grain production was increased 10% on 0.9‐m PM soil and 16% on 1.5‐m PM soil. Under Treatment II, the respective increases were 15 and 21%, but with treatments III and IV, PM had little effect on WUE. Profile modification‐induced increases in wheat grain yield and WUE were small compared to those obtained with grain sorghum and alfalfa in previous studies. Profile modification of Pullman clay loam is not a feasible practice for wheat production because of limited yield response and high energy requirements to accomplish PM.
Effect of Sulfate on Ionic Transport and Balance in a Slightly Acidic Forest Soil
Authors: Khanna P. K. , Weaver G. T. , Beese F. 
Published: July 2010

AbstractSulfate (CaSO4) was percolated at low (1.4 mg S L−1) and high (60.8 mg S L−1) concentrations, in a solution of composition equivalent to that of the canopy drip under beech (Fagus sylvatica L.) forests, through undisturbed columns of a slightly acid soil (Terra Fusca Rendzina or Lithic Rendoll). Concentrations of Ca2+, Mg2+, NO‐3, and probably HCO‐3 increased and of K decreased in the percolates. Decomposition of soil organic matter caused a significant production and subsequent leaching loss of 1.0 mmolc m2 of NO‐3 during the experimental period of 156 d. Sulfate was released by the soil during the phase of low SO2‐4 addition but was retained during the phase of high SO2‐4 addition. Production of NO‐3 and probably HCO‐3, retention and release of SO2‐4, and the release of cations involved a significant amount of production/consumption of protons in the soil. Calcium (II) and Mg2+ were leached from the soil but K+ was retained. Breakthrough curves showed peaks, usually wide, for cations when about two pore volumes of solutions had been replaced. Sulfate behaved as a reactive ion in this soil and its transport could be described by a solute transport model using suitable parameters (adsorption isotherms, apparent diffusion coefficients, bulk density, and water content), which were obtained from independent studies.
Field Denitrification Estimation by Nitrogen‐15 and Acetylene Inhibition Techniques
Authors: Mosier A. R. , Guenzi W. D. , Schweizer E. E. 
Published: July 2010

AbstractDirect quantification of denitrification N loss from N‐fertilized soils has been a long standing problem in soil N research. Recently 15N or acetylene inhibition methods have been used to make in‐field estimates of N loss from the soil resulting from denitrification. both methods have potential problems that may affect the validity of the data acquired. A field study was conducted to compare the acetylene inhibition approach with a 15N technique for measuring total N evolution (N2O + N2) from a N‐fertilized soil. Miniplots were established in an unplanted clay loam soil and fertilized with 15N‐labeled ammonium sulfate. Total N emissions were followed during three irrigation and subsequent drying events. The total N emissions measured by the acetylene method averaged 12 kg N ha−1 compared to 9 kg N ha−1 measured by the 15N technique from the nonacetylene‐treated plots. This difference between methods was small relative to the spatial variability observed in measuring gaseous N emissions in the field.
A Clay Suspension Stability End Point Titration Method for Measuring Cation Exchange Capacity of Soils
Authors: Pleysier J. , Janssens J. , Cremers A. 
Published: July 2010

AbstractThe silver‐thiourea (AgTU) method for cation exchange capacity (CEC) measurement of soils involves the assessment of Ag in the AgTU soil extracts. Silver can be easily measured by an atomic absorption spectrophotometer or with a radio isotope and scintillation counter. Laboratories for soil analysis in developing countries often do not have access to such instruments. A simple method for measuring Ag in the AgTU soil extracts was, therefore, developed. The method involves a stability end point titration of a stable montmorillonite clay suspension calibrated with AgTU solutions ranging from 5 × 10−4 to 10−2 mol L−1. The AgTU‐CEC measured by this clay titration method was compared with the “effective” CEC by NH4OAc and KCI extractions and with the AgTU‐CEC measured by an atomic absorption spectrophotometer. The correlation coefficients were 0.95 and 0.97, respectively.
Supercritical Gas Extraction of Alkanes and Alkanoic Acids from Soils and Humic Materials
Authors: Schnitzer M. , Hindle C. A. , Meglic M. 
Published: July 2010

AbstractThree soils and two humic materials were extracted with n‐pentane by supercritical gas extraction. The extracts contained a variety of compounds separated by chemical and gas chromatographic techniques and identified by gas chromatography‐mass spectrometry. The compounds identified in the extracts included n‐alkanes (ranging from n‐C12 to n‐C32), with n‐C26, and n‐C24 alkanes in prominence, and smaller amounts of cyclic alkanes (C19 to C31). The major components, however were n‐fatty acids (n‐C7 to n‐C29), accompanied by lesser amounts of branched fatty acids (C12 to C19), and unsaturated fatty acids (n‐C‐16, n‐C‐18 and n‐C‐18). hydroxy‐fatty acids (C12 to C16), and alkanoic α,ω‐diacids (C15‐C25). The overall even‐to‐odd preference indexes for the n‐alkanes and n‐fatty acids were 1.35 and 4.15, respectively, suggesting microbiological origins for these compounds. Total alkanes extracted from the soils and humic preparations ranged from 4.3 to 8.9 and 32.5 to 201.4 mg/kg, respectively. By contrast, alkanoic acids extracted varied from 94.5 to 208.9 mg/kg for the soils and 740.1 to 1576.6 mg/kg for the humic materials. Supercritical gas extraction appears to be a promising procedure for the relatively mild and efficient extraction of specific organic components from soils and humic materials.
Laboratory Apparatus to Apply and Sample Anhydrous Ammonia in Bands
Authors: Izaurralde R. C. , Kissel D. E. , Swallow C. W. 
Published: July 2010

AbstractTo describe how soil properties affect anhydrous ammonia (NH3) retention, more accurate laboratory methods are needed to apply anhydrous NH3 in a line source (band) and sample the resulting NH3 retention zone. We developed and tested a line‐source NH3 applicator and a method for sampling the resulting NH3 retention zone. The applicator has a system of flow control valves and a flow meter to regulate the rate of NH3 flow to an injection needle. The needle is held stationary while NH3 is injected into a box of soil. The box of soil moves on a platform whose speed can be varied to change the NH3 application rate. The soil sampling method was to sequentially remove concentric cylindrical cores of increasing radii centered around the line of NH3 injection. Ammonia was applied to two soils with different NH3 retention capacities and the resulting NH3 retention zones were sampled. Accurate NH3 deliveries were possible with the system described. The coefficient of variation of the platform speed was <1%. The sampling method gave N recoveries that ranged between 95 to 99%. By using the concentric ring sampling method, ammoniacal‐N concentrations of duplicate retention zones at different distances from the injection line were not significantly different. Thus, the applicator and soil sampling method proved to be both accurate and precise for studying NH3 retention zones in soil.
Argillic Horizon Expression and Classification in the Soils of Two Michigan Hydrosequences
Authors: Cremeens D. L. , Mokma D. L. 
Published: July 2010

AbstractTwo hydrosequences in central Michigan were investigated to evaluate the degree of Bt horizon expression as influenced by the depth and duration of soil saturation. Each hydrosequence was sampled in duplicate and consisted of well or moderately well, somewhat poorly, and poorly drained soils. Total clay ratios, I/E indices (fine clay/total clay of the illuvial zone divided the fine clay/total clay of the eluvial zone), and argillan development were greatest in the well‐drained soils and decreased with decreasing depth to and increasing duration of soil saturation. One of the poorly drained soils lacked Bt horizons while one had Bt horizon expression similar to that of the somewhat poorly drained soils. The water table regimes of all poorly drained soils were similar. The poorly drained soils with Bt horizons contained relatively large amounts of smectite, particularly in the clay films, while those lacking Bt horizons contained virtually no smectite. The Bt horizons developed to a greater degree where moisture fronts penetrated the solum the greater period of the year. Where penetration was retarded by soil saturation, mineralogy contributed to the degree of Bt horizon development.
Clay Minerals, Humus Complexes, and Classification of Four “Andepts” of Maui, Hawaii
Authors: Wada K. , Kakuto Y. , Ikawa H. 
Published: July 2010

AbstractClay minerals and humus complexes in the Pane, Kula, Kaipoioi, and Olinda soils, derived from basalt‐andesitic to andesitic volcanic ash on Maui, Hawaii, were studied by a combination of methods. These soils have ustic soil moisture regimes except for the Olinda, which has an udic moisture regime. The clay content of all soil samples was high (35‐73%). Allophane and/or noncrystalline Fe oxides were abundant in the Pane, Kula, and Kaipoioi soils, but they were not identified or were present only in small amounts in the Olinda soil. In the Olinda soil, layer silicates, largely of eolian origin, and hematite were major clay components. Substantial amounts of halloysite and imogolite were found in the surface and subsurface horizons, respectively, of the Pane soil. Maghemite or hematite and magnetite were major silt and fine sand components in all samples and the content of weatherable minerals was <10% except for the Kaipoioi soil. Iron and Al bound with humus increased in the soils in the order of Pane <Kula <Kaipoioi Olinda, showing an inverse relation with formation of allophane and noncrystalline Fe oxides. The organic matter inhibits the formation of allophane and imogolite by lowering of activity of Al through formation of metal‐ligand bonds. Using the U.S. system of soil taxonomy, the sampled Pane soil is classified as an Eutrandept, and the sampled Kula and Kaipoioi soils as Dystrandepts, while the sampled Olinda soil is not classified as an Andept. In the Andisol proposal, the Pane, Kula, and Kaipoioi soils would be classified as Haplustands, while the Olinda would be Hapludand. These taxonomic names require further consideration regarding the definition of the great groups or suborders of Andisols.
Water Sorption Characteristics of Aluminum‐ and Calcium‐saturated Soil Clays
Authors: Karathanasis A. D. , Evangelou V. P. 
Published: July 2010

AbstractWater sorption by Al‐ and Ca‐saturated bentonites and soil clays with montmorillonitic, mixed, illitic, and kaolinitic mineralogy were quantitatively evaluated at water vapor pressure levels (P/P0) of 0.50, 0.90, and 0.98 by thermogravimetry (TG) and differential scanning calorimetry techniques. After a 14‐d equilibration time, Al‐saturated clays adsorbed less water than Ca‐clays at low water vapor pressures but 10 to 12% more at P/P0 = 0.98. Heats of dehydration (ΔH) followed similar trends but the enthalpy required to remove 1 g of H2O from either Al‐ or Ca‐clays was approximately equal for clays with similar mineralogy. Enthalpy per unit weight of H2O decreased with decreasing interlayer space availability reaching minima in kaolinitic clays. Moisture retention differences between Al‐ and Ca‐clays at different P/P0 levels are attributed to structural organization differences of the H2O molecule—exchangeable cation network in the interlayer space as well as differential expansion at high hydration states. Practical implications of these relationships may be higher field moisture capacities, higher moisture retention during drought, and poorer field expression of cracks in acid soils with relatively high degree of Al‐saturation, especially when the soil contains significant montmorillonite quantities. Thirty‐five acid soil samples on which these relationships were tested indicated significant dependence of soil moisture characteristics on the degree of Al saturation of the clay surface.
Transport of Chloride Ion in a Water‐unsaturated Soil Exhibiting Anion Exclusion
Authors: James Ronald V. , Rubin Jacob 
Published: July 2010

AbstractMiscible displacement techniques were used to create Cl‐ concentration profiles in unsaturated laboratory columns of Delhi sand (Typic Xeropsamments), each having a nearly uniform water content. The three steady flow rates used resulted in three different, average water contents. Chloride concentrations near the top of the column were smaller and penetration of Cl‐ in the column was deeper than expected assuming that Cl‐ is a noninteracting solute. Such observations indicate the presence of anion exclusion. This interpretation is further substantiated by chloride and tritium breakthrough curves obtained from a saturated column of the same soil. The saturated experiments show that tritium occupies the entire measured pore volume of the column, but that Cl‐ is restricted to a smaller pore volume. The formulation of the conventional convection‐dispersion theory for solute transport in soil which includes anion exclusion resulted in model calculations that fitted the unsaturated Cl‐ concentration profiles quite well. The dispersion coefficients obtained for the unsaturated profiles increase with water velocity and are lower than those previously reported for comparable water velocities in the same but saturated soil. The dispersivity of the unsaturated soil is also smaller than that reported for the saturated soil. For the experimental conditions used, the effective Cl‐ exclusion volume was found to be independent of water content and velocity and occupied about ten percent of the unsaturated water content.
Effect of Acidity on Nitrogen Mineralization and Nitrification in Atlantic Coastal Plain Soils
Authors: Weier K. L. , Gilliam J. W. 
Published: July 2010

AbstractThe objective of this study was to determine the effect of acidity on mineralization, nitrification, and N2O evolution during these processes on naturally acid soils from the lower Coastal Plain of North Carolina. Six acid surface soils (pH ≤4.5) from the Tidewater region of North Carolina, with a range of organic matter (OM) contents (28‐850 g kg−1) were limed to give a range of pH values so that the effect of acidity on mineralization of organic N and nitrification of (NH4)2SO4 could be studied under controlled conditions in the laboratory. Cumulative net mineralization over 21 d was significantly (p <0.01) influenced by acidity in four of the six soils. However, no soil exhibited a significant net mineralization increase between the very acid initial pH value and the pH value to which liming is recommended (pH 4.8‐5.2 for Histosols) for crop production. Liming to pH values <7 increased net mineralization in only one soil. Adding a small increment of lime tended to decrease mineralization although this effect was significant in only one soil. Essentially all organic N mineralized was converted to NO‐3 at all pH values. However, the very high acidities tended to inhibit the nitrification of NH+4 added as (NH4)2SO4. There was apparently no influence of organic matter content on any of the processes studied except N2O evolution where the soils with <120 g OM kg−1 evolved the highest amounts of N2O during nitrification. Much of the N2O evolution was apparently due to denitrification because addition of nitrapyrin did not eliminate the evolution. It was concluded that the liming of acid soils in the Tidewater Region of North Carolina would have little influence upon N mineralization rates. The recommended pH values of 4.8 to 5.2 for Histosols appears to be adequate for both mineralization and nitrification.
A Nonweighing Lysimeter Design for Field Studies Using Nitrogen‐15
Authors: Reeder J. D. 
Published: July 2010

AbstractThis paper describes the design and use of a nonweighing lysimeter in a field study in which 15N cycling was monitored within a revegetated disturbed‐land ecosystem over a period of 5 yr. The design successfully overcame sampling problems associated with a rocky terrain. Recovery of added 15N was satisfactory, with <10% of added 15N unaccounted for two seasons after application. However, the water content of the natural spoil profile could not be exactly duplicated in the lysimeter. Although the lysimeter was designed to minimize sampling problems associated with a specific research site, the design is applicable to other field conditions in which leaching losses need to be monitored.
Influence of Soil Organic Matter Concentrations on Carbon and Nitrogen Activity
Authors: Woods L. E. , Schuman G. E. 
Published: July 2010

AbstractThe relationship of soil organic matter (OM) concentration to microbial biomass concentration and mineralizable OM is central to understanding the establishment and functioning of soil nutrient cycles. These parameters are presumably related to aboveground plant biomass and plant N concentration, but the mechanisms and controls of these interactions are not well understood. To further evaluate these relationships, a field study was established in a series of soil materials whose organic C concentrations ranged from 1 to 21 g kg−1. Surface soil (0‐15 cm) and vegetation samples were collected from plots of each treatment during the 1983 growing season. Microbial biomass was measured by chloroform fumigation and incubation; mineralizable C and N were measured in 20‐d laboratory incubations; plant growth was measured by weighing material clipped from 0.18‐m2 frames; and plant N concentration was measured by Kjeldahl digestion and colorimetric analysis. Microbial biomass increased linearly with soil OM concentration. Mineralizable N and plant production also increased with soil OM, but were greater with 7 than with 15 g kg−1 of organic C. Even though aboveground plant biomass was greater with either 7 or 15 than with 21 g kg−1 organic C, plant N concentrations were highest with 21 g kg−1. Soil OM concentrations were more closely related to microbial biomass than to mineralizable C and N, or to plant biomass and plant N concentrations. Nitrogen mineralization in the laboratory corresponded to plant N concentration in the field. Soil OM concentrations controlled microbial biomass C and N concentrations. However, additional factors also influenced the activity of the microbes and the resultant OM mineralization and plant N concentrations.
Modeling the Plant Uptake of Cadmium and Zinc from Soils Treated with Sewage Sludge
Authors: Mullins G. L. , Sommers L. E. , Barber S. A. 
Published: July 2010

AbstractTo evaluate models for predicting plant uptake of Zn and Cd, a growth chamber study was conducted with soils collected from research plots in Ohio, Indiana, Michigan, and Wisconsin that had been treated 4 yr previously with 100 Mg ha−1 of an anaerobically digested sewage sludge from Chicago, IL. The single application of sludge supplied 19‐kg Cd and 340 kg Zn ha−1. Sludge application increased the concentration of Cd and Zn in the shoots and roots of corn (Zea mays L.) seedlings grown for 16 and 22 d in the four soils. The application of sludge had no effect on the growth and properties of the corn root systems. Soil characteristics and kinetic parameters for Zn and Cd uptake were combined with a nutrient uptake model to predict Cd and Zn uptake by corn seedlings. In the untreated and sludge‐treated soils predicted Cd uptake (Y) was related to observed uptake (X) in nmol pot−1 by: Y = 90.03 + 1.41X (r = 0.81). Overprediction of Cd uptake by 41% may have resulted from an incorrect value of the Michaelis‐Menten constant, Km, and/or neglecting Cd efflux from roots. Calculated Zn uptake in the untreated and sludge‐treated soils was related to observed uptake by: Y = 3.29 + 0.857X (r = 0.91) where units for Y and X are µmol Zn pot−1. A sensitivity analysis was conducted with the model to determine how each soil and plant factor affected predicted Cd and Zn uptake. Plant factors that had the greatest effect on Cd and Zn uptake include the root growth constants, average root radius, and water influx rate. Kinetics of Cd and Zn uptake and half‐distance between roots had little effect on Cd and Zn uptake. Concentration of Cd and Zn in the soil solution (Ci) was the soil parameter showing the greatest effect on predicted metal uptake. In comparison, average buffer power and diffusion coefficients for Zn and Cd had minimal impact on predicted metal uptake.