bluuebunny/crossref_metadata_2025_split huggingface dataset:
Denitrification and Nitrous Oxide Production in Successional and Old‐Growth Michigan Forests
Authors: Robertson G. Philip , Tiedje James M. 
Published: July 2010

AbstractSoils from 12 successional and old‐growth forests in Michigan were examined for N2O production under each of three incubation conditions: without amendment, in a 20% (vol/vol) acetylene atmosphere, and in an acetylene‐amended atmosphere after a simulated rainfall. Intact cores were taken during the growing season and incubated in the laboratory for 90 to 180 min in a porespace‐recirculation system that sampled for N2O and CO2 at 10‐min intervals. Measurable rates of N2O production occurred in cores from all sites and under all incubation conditions; in general but not always, rates were higher in the presence of C2H2 than in its absence, and increased upon simulated rainfall. Under acetylene‐ and water‐amended conditions, mean production was highest in an old‐growth and a late‐successional hardwood site and in a recent clearcut (30 to 80 mg N2O‐N m−2 d−1); intermediate rates (2 to 3 mg N2O‐N m−2 d−1) were observed in soils from a midsuccessional hardwood stand and from two old‐field communities, and low rates (<0.6 mg N2O‐N m−2 d−1) occurred in soils from a young sand dune community, from a midsuccessional and a late‐successional hardwood stand, and from a managed, a midsuccessional, and an old‐growth conifer community. Nitrate production, CO2 production and water content could explain 65% of the variation in rates of N2O production among sites under acetylene‐amended conditions. Nitrate pool sizes and pH differed substantially among sites but were not well correlated with N2O production. The presence of a class of cores that produced N2O only in the absence of acetylene suggests that sources of N2O other than denitrifiers may be important in some sites.
Potassium Chloride for Improved Urea Fertilizer Efficiency
Authors: Rappaport B. D. , Axley J. H. 
Published: July 2010

AbstractMuriate of potash (KCl), a major source of fertilizer K, can be applied in combination with urea [(NH2)2CO] to reduce ammonia (NH3) volatilization. Addition of KCl in combination with urea to fertilize field crops should not increase fertilizer costs.Laboratory investigations with a Klej loamy sand (Aquic Quartzipsamments) showed that a combination of 1 part urea with 1 part or greater of KCl (by weight) as a fertilizer solution reduced ammonia losses from 42% to 4.6% or less.Application of 1 part of KCl to 1 part urea in a liquid fertilizer increased sorghum‐sudan grass (Sorghum sudanese L.) hay yields over that of urea alone by 85 g m−2 in field studies on a Galestown sandy loam (Psammentic Hapludults). Also, 0.77 parts of KCl to 1 part of urea was equally beneficial. Yield of field corn (Zea mays) on a Hagerstown silt loam (Typic Hapludalfs) was increased by urea in combination with potassium chloride over urea alone by 113 g m−2.
Contour‐Lined Photobase Maps for Soil Mapping
Authors: Hodges Robert L. , Baker James C. , Darling Dennis 
Published: July 2010

AbstractContour‐lined photobase maps have proved advantageous to soil scientists making soil surveys in the wooded areas of the Coastal Plain of Virginia. On conventional, unlined aerial photographs, dense vegetative regrowth of cut over woodlands appear as uniform tones. This restricts photo interpretation, making accurate depiction of soil boundaries difficult. Contour‐lined photobase maps allow the soil scientist to maintain location within the accuracy of the topographic map, resulting in increased accuracy in soil boundary placement. In the Coastal Plain of Virginia, contour‐lined photobase maps have facilitated an increase in the mapping rate.
Boron Adsorption by Montmorillonite as Affected by Particle Size
Authors: Keren R. , Talpaz H. 
Published: July 2010

AbstractThe effect of clay particle size on B adsorption by the Na and Ca forms of montmorillonite was determined at two pH levels. Boron adsorption by the smaller clay particles of both Na and Ca forms was much greater than by the larger clay particles at both pH levels. The increase in B adsorption in the smaller clay particle systems was related to the increase in the edges' surface area of the clay platelets. Data from batch experiments were compared with results computed according to fitted adsorption coefficients (maximum B adsorption and affinity coefficients which related to the binding energy). The agreement between calculated values and experimental results indicates that the adsorption model can be used to predict B adsorption by Na‐ and Ca‐montmorillonite at various particle sizes.
Amendment of Mine Spoil to Increase the Number and Activity of Microorganisms
Authors: Lindemann W. C. , Lindsey D. L. , Fresquez P. R. 
Published: July 2010

AbstractIf mine spoil areas are not topsoiled in spoil reclamation, microbial numbers and activities may need stimulation. The objectives of this study were to determine the effect of spoil amendment on microbial parameters and mycorrhizal infection of grass species in the field. Spoil on the San Juan coal mine near Farmington, New Mexico was amended with hay, sludge, or topsoil inoculum, or was covered with 30 cm of topsoil as normally practiced. Microbial parameters measured in both the rhizosphere and nonrhizosphere included numbers of bacteria, Streptomyces, ammonium oxidizers, Azotobacter, dehydrogenase enzyme activity and fungal genera distribution. Mycorrhizal inoculum (roots and soil containing Glomus mosseae and G. fasciculatum) was also applied and plants were examined for percentage mycorrhizal roots. The addition of either sludge or hay or topsoiling increased the number of microorganisms, enzyme activity and fungal genera distribution in nonrhizosphere spoil. Topsoil added as an inoculum had little or no effect on these biological factors. Only the number of Azotobacter was significantly increased in the rhizosphere by spoil amendment. Providing an available carbon source was more critical in stimulating an active and varied microflora than was a topsoil inoculum. Mycorrhizal infection was poor in all treatments. Amendments had no or little effect on percentage mycorrhizal roots. Covering the spoil with 30 cm of topsoil provided the greatest amount of mycorrhizal infection.
Fate of Labeled Nitrogen Fertilizer Applied to Winter Wheat for Five Years
Authors: Olson R. V. , Swallow C. W. 
Published: July 2010

AbstractTo assess the effect of time and rate of fertilizer N applications on fate of the applied N, a 5‐yr field experiment was conducted with winter wheat (Triticum aestivum L.). Microplots confined in metal frames to a depth of 1.42 m received annual applications of (NH4)2SO4 containing 7.65 atom %15N. Treatments, replicated four times, consisted of 50 and 100 kg N/ha applied in fall and spring on a Pachic Argiustoll soil. In four of the years, spring applications gave better fertilizer use efficiency than fall treatments, probably because of greater immobilization of fall‐applied N. After 5 yr, 27 to 33% of the applied fertilizer N had been removed by the grain. Soil N use was increased by fertilizer in some years and in those cases was correlated highly with increased growth, suggesting that the cause was larger root systems rather than a priming effect. Amounts of fertilizer N in the 1.8‐m soil profiles increased each year and at the end of the experiment averaged 54% of that applied during the 5 yr for 50‐kg treatments and 47% for 100‐kg treatment. From 71 to 77% of the surface‐applied fertilizer N remaining in the profiles was in the 0‐ to 0.1‐m soil layers. Most of the residual fertilizer N was immobilized in organic forms, but late applications and dry conditions in 1980 greatly reduced both nitrification and immobilization. There was good agreement between 15N and difference measurements of crop removal of fertilizer N for the 5‐year period, although difference measurements were more variable and did not agree well with 15N measurements in individual years.
Ultrasonic Dispersion of Soil Aggregates Stabilized by Polyvinyl Alcohol and T403‐Glyoxal Polymers
Authors: Moen D. E. , Richardson J. L. 
Published: July 2010

AbstractAggregate and structural analysis of soils treated with polymeric soil conditioners has proved to be a problem and prompted this study utilizing an ultrasonic dispersion method. Two Red River Valley soils, a Glyndon loam and a Fargo silty clay were tested along with a mine spoil material from near Zap, North Dakota. The Fargo and Glyndon soils were treated in the laboratory with T403‐glyoxal, a newly developed two‐phased amine‐aldehyde polymer, and polyvinyl alcohol (PVA). The dispersion created by an ultrasonic power input of 37.5 W for 30 to 400 s was determined by pipette analysis. The percent clay remaining undispersed decreased exponentially with increased time of exposure to ultrasound. Stability of sample aggregates was determined by the initial dispersion value and strength of aggregates by the rate of dispersion (slope). Tests using a sodium‐affected minespoil material resulted in low values for both stability on wetting and aggregate strength thus supporting the methods used. Polymer treatments resulted in 50% increases in stability on wetting and large increases in aggregate strength. Samples treated with 1% PVA or 5% T403‐glyoxal were made effectively coarser because of the extreme strength of microaggregates. Polyvinyl alcohol was much more effective per unit weight than T403‐glyoxal, but the latter was effective in creating very strong microaggregates (<0.25 mm), which effectively reduced plasticity of the soils.
Formation of Ferric Oxyhydroxides from Ferrous and Ferric Perchlorate in Stirred Calcareous Systems
Authors: Loeppert R. H. , Hossner L. R. , Amin P. K. 
Published: July 2010

AbstractReactions between Fe salts and CaCO3 are important in influencing the nutrient availability of Fe in calcareous soils and are also important in soil pedogenic processes. The objective of this study was to investigate the reaction between Fe2+ or Fe3+ and CaCO3, especially with regard to influence of CaCO3 surface area and PCO2 on rate of reaction and Fe oxide product. Ferrous or ferric perchlorate, 0.01M, was reacted with calcite in stirred aqueous suspensions while bubbling vigorously with an oxidizing purge gas. Redox potential and pH were monitored continuously during the reactions. Upon addition of Fe(ClO4)2 to an aqueous calcite suspension, pH was initially controlled by the solution phase Fe at approximately 5.0 to 6.0; however, as the Fe salt was completely precipitated there was a rapid rise in pH to the equilibrium pH of calcite. In all cases, pH and redox endpoints corresponded closely. Rate of reaction was strongly dependent on CaCO3 surface area. With the Fe(ClO4)2 system and with air as the purge gas, rate of reaction was linearly related to calcium carbonate surface area. Increased PCO2 resulted in reduced rates of reaction and deviation from the linear relationship between surface area and rate of reaction. With the Fe(ClO4)2 system, mineralogy of the Fe oxide product as determined by x‐ray diffraction was influenced by PCO2. Lepidocrocite and goethite were the dominant products formed in the presence of air and 20% CO2 (balance air), respectively. With the Fe(ClO4)3 system, poorly crystalline ferrihydrite was the only product obtained.
Macroporosity to Characterize Spatial Variability of Hydraulic Conductivity and Effects of Land Management
Authors: Ahuja L. R. , Naney J. W. , Green R. E. , Nielsen D. R. 
Published: July 2010

AbstractTo develop simplified methods of hydraulic characterization of field soils and effects of management, frequency distribution of macroporosity (or effective porosity) in a soil is investigated as a measure of its saturated hydraulic conductivity distribution. The effective porosity (φe) of a soil is related to its saturated hydraulic conductivity (Ks) by a generalized Kozeny‐Carman equation. The exponent of this relationship is assumed to vary within a narrow range (value of 4 or 5). The equation is then combined with scaling theory to derive the frequency distribution of Ks scaling factors from the φe distribution. These concepts are tested on experimental data for two widely different soils, a mollisol and an oxisol. The φe is defined as total porosity minus soil water content at −33 kPa pressure head. The exponent of the Ks‐φe relationship is found to be nearly 4 for the soil‐core data of both soils, while for a smaller set of in‐situ field data for oxisol, which was within a narrow range of φe, the value of the exponent was smaller. There was a considerable scatter in the relationships. However, with the exponent set equal to 4 or 5 the distribution of Ks scaling factors derived from φe distribution closely matched the experimental Ks‐derived distribution. The approach has a promise for large‐scale applications.
Hydraulic Conductivity and Water Retention of Clay Soils Containing Coarse Fragments
Authors: Ravina Israela , Magier Joshua 
Published: July 2010

AbstractField observations show that clay soils with medium to high coarse fragment contents are less compacted, have a more favorable structure and provide better physical condition for tree growth than similar soils containing small amounts of coarse fragments. The effect of coarse fragments on soil compaction, hydraulic conductivity, and moisture retention at low suctions was investigated. Increasing coarse fragment content increased resistance to compaction and consequently preserved lower soil bulk density. Larger volumes of large pores were found after compaction of soil with increasing coarse fragment content. In compacted soils of increasing coarse fragment content, hydraulic conductivity was higher. Aerated porosity of soils between fragments increased with increasing fragment content. It was concluded that coarse fragments contribute to improved physical conditions by acting as a “skeleton,” which resists soil compaction.
Aerobic and Anaerobic Microbial Populations in No‐till and Plowed Soils
Authors: Linn D. M. , Doran J. W. 
Published: July 2010

AbstractSurface soils from long‐term tillage comparison experiments at six U.S. locations were characterized for aerobic and anaerobic microbial populations and denitrification potential using an in situ acetylene blockage technique. Measurements of soil water content, bulk density, and relative differences in pH, NO‐3‐N, water‐soluble C, and total C and N contents between tillage treatments were also determined at the time of sampling. Numbers of aerobic and anaerobic microorganisms in surface (0–75 mm) no‐till soils averaged 1.35 to 1.41 and 1.27 to 1.31 times greater, respectively, than in surface‐plowed soils. Bulk density, volumetric water content, water‐filled pore space, and water‐soluble C and organic C and N values were similarly greater for surface no‐till soils compared to conventionally tilled soils. Deeper in the soil (75–300 mm), however, aerobic microbial populations were significantly greater in conventionally tilled soils. In contrast, below 150 mm, the numbers of anaerobic microorganisms differed little between tillage treatments. In no‐till soils, however, these organisms were found to comprise a greater proportion of the total bacterial population than in conventionally tilled soils. Measurements of the denitrification potential from soils at three locations generally followed the observed differences in anaerobic microbial populations. Denitrifying activity, after irrigation with 15 mm of water, was substantially greater in surface 0‐ to 75‐mm no‐till soils than in conventionally tilled soils at all locations. At the 75‐ to 150‐mm soil depth, however, the denitrification potential in conventionally tilled soils was the same or higher than that of no‐till soils. In surface no‐till soils, increased numbers of anaerobic microorganisms and a substantially greater denitrification potential, following irrigation, indicate the presence of less‐aerobic conditions in comparison to conventionally tilled soils. This condition appears to result from greater soil bulk densities and/or water contents of no‐till soils, which act to increase water‐filled porosity and the potential for water to act as a barrier to the diffusion of oxygen through the soil profile.
Soil Temperature Effects on Root Growth and Phosphorus Uptake by Corn
Authors: Mackay A. D. , Barber S. A. 
Published: July 2010

AbstractTemperature affects each of the mechanisms involved in P uptake by corn. The extent to which each reduces P uptake, however, has not been resolved. The objective of this study was to determine the effect of temperature on each of the parameters used in a mechanistic mathematical model that predicts P uptake and then to use the model in a sensitivity analysis to evaluate the temperature dependency of parameters critical for predicting P uptake by corn. The effect of soil temperature, 18 and 25°C, and soil P status on root growth and P uptake by corn (Zea mays L.) was investigated in a series of pot experiments in a controlled climate chamber. Total yield of corn was 4‐ to 6.4‐fold, root growth 2.6‐ to 5.1‐fold, and P uptake 2‐ to 4‐fold greater at 25°C than at 18°C. Increasing air temperature to 25°C while holding soil temperature at 18°C resulted in a 2.7‐fold increase in root growth and a 2.2‐fold increase in P uptake. Predicted P uptake calculated with a mechanistic mathematical model by corn grown for 8, 15, and 21 d agreed with observed P uptake at both 18°C (y = 0.97x + 3.64, r = 0.99**) and 25°C (y = 1.07 x − 1.86, r = 0.99**). In the sensitivity analysis the parameters used to calculate P uptake at 18°C were changed individually to those measured at 25°C and then P uptake was again predicted. Rate of root growth, which increased 4.97‐fold when temperature increased from 18 to 25°C, had the most pronounced effect on calculated P uptake, indicating that this was the primary reason low temperature reduced P uptake by corn. The parameters describing the movement of P to the root surface and P uptake at the root surface appear to play only a minor role in causing reduced P uptake by corn at low temperature.
Effects of Desurfacing of Alfisols and Ultisols in Southern Nigeria: I. Crop Performance
Authors: Mbagwu J. S. C. , Lal R. , Scott T. W. 
Published: July 2010

AbstractThe widespread incidence of soil erosion in the tropics has been reported but few studies have dealt with the specific problem of decline in crop productivity associated with the soil loss. An understanding of the effect of topsoil loss on crop yield is needed in order to develop some management practices for restoring productivity on eroded soils. The effects of topsoil removal on maize (Zea mays L.) and cowpea (Vigna unguiculata L.) grain yields and their response to N and P rates were investigated in one double cropping sequence on an Ultisol at Onne in southeast Nigeria, and two Alfisols at Ikenne and Ilora in southwest Nigeria. In comparison with unfertilized uncut control, maize grain yield was reduced by 95.4, 95.4, and 100% at Onne, 30.5, 73.6, and 93.5% at Ikenne, and 72.5, 82.6, and 99.5% at Ilora for 5‐, 10‐, and 20‐cm soil depths removed, respectively. Cowpea yield reductions were 62.7, 70.6, and 68.3% at Onne, 1.5, 59.1, and 65.1% at Ikenne and 42.6, 33.1, and 80.5% at Ilora for 5, 10, and 20 cm of soil removal, respectively. None of the fertilizer combinations used was an effective substitute for topsoil removed at Onne during the two seasons and at Ilora during the second season. The rate of 60 and 120 kg N ha−1 in combination with 30 kg P ha−1 restored maize yield at Ikenne equivalent to or within 4% of the control for 5 cm soil removed. At Ilora combinations of 60 and 120 kg N ha−1 and 15 and 30 kg P ha−1 produced maize grain yields equivalent to or within 43% of control where 5 cm soil was removed.
Effect of Exchangeable Sodium and Phosphogypsum on Crust Structure—Scanning Electron Microscope Observations
Authors: Gal M. , Arcan L. , Shainberg I. , Keren R. 
Published: July 2010

AbstractThe effect of soil sodicity and phosphogypsum treatment on the structure of the crust of two soils (sandy loam and clay soil) was studied using a scanning electron microscope (SEM). The crust of the sandy loam with ESP 1.0, and the two soils at all levels of sodicity when treated with phosphogypsum, consisted of a compacted skin seal attributed to the mechanical impact of raindrops. Little clay movement or development of a “washed in” layer was observed under these conditions. Conversely, when the ESP > 1.6 (in the two soils) the crust consisted of naked sand and silt grains over a dense “washed in” layer. The compacted layer of disintegrated aggregates is not stable when soil and water conditions are favorable for clay dispersion (sodic soils and low electrolyte soil solutions). In soils with no exchangeable sodium, aggregate breakdown and surface compaction by raindrops are the dominant mechanisms for crust formation. In soils with ESP values above 1.5, chemical dispersion of the soil clays (enhanced by the sodicity of the soil, the low electrolyte concentration in the rain, and the stirring effect of the raindrops) and the downward movement of the clays into the “washed in” layer clogging the pores in this layer were the dominant mechanisms in crust formation. Soils with a “washed in” layer had a very low infiltration rate.
Konyaite in Salt Efflorescence from a Tertiary Marine Deposit near Geelong, Victoria, Australia
Authors: Shayan A. , Lancucki C. J. 
Published: July 2010

AbstractKonyaite [Na2Mg(SO4)2·5H2O] was identified for the first time in Australia in salt efflorescences from a Tertiary marine deposit below exposed basalt flows at a quarry near Geelong, Victoria. Other soluble salts in the efflorescence were epsomite (MgSO4·7H2O), gypsum (CaSO4·2H2O), and halite (NaCl). Heating at 110°C converted the konyaite to a mixture of bloedite [Na2Mg(SO4)2·4H2O], loeweite [Na4Mg2(SO4)4·5H2O], and thenardite (Na2SO4). Recrystallization at 23°C of the efflorescence dissolved in varying amounts of water indicated that epsomite and thenardite form from dilute solutions, whereas increasing amounts of konyaite recrystallize from the more concentrated solutions under faster evaporative conditions. The salts are transported to the basalt quarry site in river seepage or ground water from the neighboring marine deposits and are left on the exposed surfaces by evaporation.
Routine Procedure for Rapid Determination of Soil Carbonates
Authors: Loeppert R. H. , Hallmark C. T. , Koshy M. M. 
Published: July 2010

AbstractA procedure is presented for the routine determination of soil carbonates based on the following reaction: CaCO3 + 2 HC2H3O2 → Ca2+ + 2 C2H3O2‐ + H2O + CO2 (g) A known quantity of acetic acid is added to a known quantity of soil. The pH of the reaction mixture is then determined following complete dissolution of CaCO3. Calcium carbonate content is determined empirically from a standard curve relating pH to known CaCO3 content according to the equation: pH = K + n log [CaCO3/(T − CaCO3)], in which T equals the total amount of calcium carbonate which could be completely dissolved by the acetic acid added to the system, and K and n are constants. Several possible sources of error exist in the procedure; however, potential errors may be minimized by the maintenance of optimum working conditions. Results obtained by the acetic acid procedure compared favorably with results obtained by the Chittick procedure. The proposed procedure has the advantage of simplicity and offers a rapid alternative for routine determination of soil carbonates.