bluuebunny/crossref_metadata_2025 huggingface dataset:
Clothianidin Seed Treatments Inconsistently Affect Corn Forage Yield When following Soybean
Authors: Cox William J. , Cherney Jerome H. , Shields Elson
Published: March 2007

Cool conditions after corn (Zea mays L.) planting frequently delay emergence in the northeastern USA, which is conducive to damage by the soil insect pest, seed corn maggot (Delia platura). Two hybrids with three seed‐applied insecticide treatments, which included a control, 0.25 mg a.i. seed−1 clothianidin [(E)1‐(2‐chloro‐1, 3‐thiazol‐5‐ymethyl)‐3‐methyl‐2‐nitroguanidine], and 1.25 mg a.i. seed−1 clothianidin, were evaluated in 2004 and 2005 in New York. The objective of the study was to determine if clothianidin affects final plant densities, total dry matter (DM) accumulation during vegetative growth, DM yield, and forage quality in an environment with occasional soil insect pests. Corn emerged in 7 d in 2004 so clothianidin did not affect final plant densities, but the 1.25 mg a.i. treatment vs. the control of one hybrid had 1.3 Mg ha−1 greater DM yield. Corn emerged in 17 d in 2005, and the 0.25 mg a.i. treatment averaged 3296 more plants ha−1 while both clothianidin treatments vs. the control of one hybrid had 1.4 to 1.7 Mg ha−1 greater DM yields. Lack of negative responses of final plant densities, vegetative growth, and DM yield indicates that clothianidin seed treatments have no phytotoxic effect on corn. Nevertheless, seed treatments did not affect forage quality or calculated milk yields so our study indicates that clothianidin seed treatment is not justified when corn follows soybeans [Glycine max L. (Merr)] in the northeastern USA.
Effect of Winter Wheat Crop Residue on No‐Till Corn Growth and Development
Authors: Kravchenko Anatoliy G. , Thelen Kurt D.
Published: March 2007

Two established methods for increasing the sustainability of production agricultural cropping systems are (i) increasing crop residue levels by reducing tillage and (ii) including a winter annual crop in the rotation. A wide range of crop yield responses have been reported for no‐till systems adopted to a corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. However, little research has been done in the Northern Corn Belt on no‐till corn following winter wheat (Triticum aestivum L.). The objective of this study was to evaluate the effect of winter wheat crop residue on the growth and development of no‐till corn. The experimental design was a randomized complete block. Treatments consisted of no‐till systems with three levels of winter wheat residue [no wheat residue (NWR), wheat root residue only (WRR), and wheat root and shoot residue (WRSR)]. Data were collected in 2003, 2004, and 2005. Measurements included plant emergence, plant height, time of tasseling (VT stage), chlorophyll content, presidedress soil nitrate test (PSNT) soil nitrate levels, soil moisture and temperature, corn grain yield, grain moisture, and grain test weight of corn at harvest. In all years, the presence of winter wheat residue above and below ground decreased soil temperature, increased soil moisture, and decreased chlorophyll content in corn leaves and plant height in the early stages of corn development. The VT stage of corn was delayed for about 1 wk in residue systems. Winter wheat residue decreased the amount of plant available N and increased grain moisture and test weight of corn grain at harvest. Emergence and population of corn in 2003 and 2005 were reduced in residue systems. The use of a PSNT‐based N application rate was successful in maintaining corn grain yield in wheat residue systems with corn grain yield in NWR systems in 2003 and 2004 despite wheat residue antagonism of corn growth and development. In 2005, corn grain yield in wheat residue treatments was less than in NWR treatments, but was equal to PSNT target yields.
Competitive Adsorption of Heavy Metals in Humic Substances by a Simple Ligand Model
Authors: Jeong Chang Yoon , Young Scott D. , Marshall Stewart J.
Published: March 2007

Proton and metal ion binding to humic acids has been recognized as an important factor in controlling metal speciation and mobility in aqueous and soil environments. The binding and competition behavior of humics has not been fully described, however, due to the polydisperse mixtures of natural organic polyelectrolytes with different functional groups. The simplified discrete binding group type of model (Model A) was used in this study. Model A was applied to describe three single metals and their competitive binding on the humic acids. Model A considers only a single carboxyl group type and a single phenolic hydroxyl group type with a variable electrostatic interaction factor that is expressed as a polynomial equation. Metal binding experiments were performed using a batch‐type dialysis equilibration method, and mass and charge balance expressions were used to calculate individual components of the system. The fit of Model A suggested that the major binding site for the three metal ions tested (Cd, Zn, and Cu) was a bidentate chelate of the carboxyl groups. Model A described two‐ and three‐metal competition on the humic acids using the intrinsic stability constant for the single metal ion. The model used in this study adequately described the competition of two metals; however, it showed weaknesses when applied to more complex systems, especially when metals with substantially different binding characteristics were present. Model A presented a better prediction with adjusted Cu concentration (2:1:1 Cu/Cd/Zn).
Soil Microbial Fingerprints, Carbon, and Nitrogen in a Mojave Desert Creosote‐Bush Ecosystem
Authors: Ewing Stephanie A. , Southard Randal J. , Macalady Jennifer L. , Hartshorn Anthony S. , Johnson Mara J.
Published: March 2007

Creosote‐bush [Larrea tridentata(Sessé & Moc. ex DC.) Coville] shrubs in California's Mojave Desert support well‐developed soil resource islands, where individual shrubs define areas of elevated soil nutrients, water‐holding capacity, and microbial activity. To better understand the spatial variability of microbial communities and potential impacts on nutrient cycling in shrub ecosystems, we examined microbial communities using polar lipid fatty acids (PLFA) and several soil properties including δ15N, DNA, C and N contents under mature shrubs and as a function of horizontal distance (0–3 m) away from the base of the shrubs. Shrub‐base soils (0 m) contained more C and N, were slightly more acidic, and supported significantly larger microbial populations than soils between shrubs. The PLFA fingerprints also suggested that microbial communities, particularly at the shrub base, had a different composition than soils between shrubs, including a higher proportion of actinomycetes containing the biomarker 10me17:0. Soil respiration was generally highest at 0 m, corresponding with larger microbial biomass and larger C and N pools, but was highly variable, probably due to contributions from grasses and forbs. Average δ15N values resembled plant material at the shrub base (4‰) and were significantly isotopically enriched away from the shrubs (7‰), suggesting that fractionating losses of soil N occurred between shrubs. The elevated nutrient status of resource islands supported soil microbial communities that were larger, were different in character, respired more actively, and cycled N more tightly than those found in open spaces between shrubs. These open spaces “leak” isotopically light N from the soil.
Carbon Dynamics under Long‐Term Conservation and Disk Tillage Management in a Norfolk Loamy Sand
Authors: Novak J. M. , Bauer P. J. , Hunt P. G.
Published: March 2007

Soil organic carbon (SOC) sequestration is an important process to mitigate CO2 emissions. Our objectives were to determine the rates of C sequestration and to determine if the SOC pool was at or approaching equilibrium in plots under long‐term (24‐yr) conservation (CT) and disk tillage (DT) management. The plots were Norfolk loamy sand (fine‐loamy, kaolinitic, thermic, Typic Kandiudult) and were under a row crop rotation. All plots received annual subsoiling, while only plots under DT were surface disked. Soil cores were collected to 90 cm deep. After 24 yr, the only significant increase in SOC occurred in CT plots at a 0‐ to 5‐cm depth. The SOC pool in plots under DT was at a near‐steady state, while the SOC pool under CT was not at equilibrium. This supports the conclusion that CT is an effective countermeasure to offset atmospheric CO2 emissions.
Effect of Transient Irrigation on Boron Transport in Soils
Authors: Communar G. , Keren R.
Published: March 2007

Water redistribution and solute concentration changes caused by water evaporation can affect B transport in unsaturated soils under a subsurface transient water flow regime. Our objective was to assess the effect of nonequilibrium adsorption on B transport in unsaturated, homogeneous soil under periodic infiltration cycles using adsorption and transport parameters obtained from independent batch and column experiments. Column experiments using flow interruption were conducted at two pore‐water velocities: 0.25 and 2.5 cm h−1 Transport of B at low velocity was unaffected by flow interruption, whereas interruption of fast flow resulted in appreciable perturbation of the B concentration in outflows. The convection–dispersion equation (CDE) with a rate‐limited reaction term was fitted to the fast‐flow B breakthrough curves (BTCs) to determine the mass‐transfer rate coefficients controlling nonequilibrium B transport behavior in soils. This CDE, coupled with the Richards equation, was used to simulate B transport in unsaturated soils under irrigation cycles consisting of water infiltration, internal drainage (redistribution), and evaporation. The B transport under transient nonmonotonic flow depended strongly on the rate‐limited step of B adsorption. At a small value of the mass‐transfer coefficient, the B BTCs had a characteristically jagged shape, showing increase–decrease cycles in solution B concentrations. The B adsorption tended to balance the solution B concentration increase caused by water evaporation. The final B concentrations, however, exceeded unity in the upper part of the BTCs that were obtained at different soil depths. The results revealed that deviation from adsorption equilibrium may lead to appreciable changes in solution B concentration, especially in the topsoil where the water flow is explicitly transient and nonmonotonic.
Prediction of Soil Organic Carbon Content Using Field and Laboratory Measurements of Soil Color
Authors: Wills Skye A. , Burras C. Lee , Sandor Jonathan A.
Published: March 2007

The understanding, prediction, and modeling efficacy of soil organic carbon (SOC) distribution across fields and larger regions requires a large number of samples that are costly to analyze. The objective of this study was to evaluate soil color measurements to predict SOC for agriculture and prairie land uses. Munsell soil color book (B) and chroma meter (C) color readings were taken at the midpoint depth of each horizon (HB and HC) and predetermined depth increments (IB and IC) on 125 cores. Horizon matrix (HD) colors were determined by standard description. A chroma meter was used to determine the color of prepared samples, ground to <2 mm. Both color data sets were used in a regression analysis to predict SOC content by weight and volume. The best predictors for each technique are the models that incorporate Munsell value and chroma along with the depth from which the measurement was taken. Separating samples by land use improved the prediction of SOC. Transforming SOC content by log10 improved the coefficient of determination for nearly all models. The best predictors of SOC were HD for SOC by weight (agricultural field r2 = 0.79, prairie r2 = 0.53), HB for SOC by volume (agricultural field r2 = 0.76, prairie r2 = 0.57), and IC and IB for log‐transformed SOC by weight and volume (agricultural field r2 = 0.84, prairie r2 = 0.62). This study indicates that while SOC content predictions can be made with field measurements, there are limitations to their predictive usefulness.
Mapping Peatlands in Ireland using a Rule‐Based Methodology and Digital Data
Authors: Connolly John , Holden Nicholas M. , Ward Shane M.
Published: March 2007

Peatlands have been recognized as being an important global C pool and make significant contributions to national C fluxes. In Ireland, they cover a considerable amount of the national land area, but no recent inventory or mapping has been undertaken to quantify the spatial extent of this important resource. This study used a rule‐based methodology implemented as a series of hierarchical rules in ArcGIS to estimate the extent of contemporary peatlands in Ireland from soil and land‐cover maps dating from the 1970s, 1980s, and 1990s. The Derived Irish Peat Map was produced at a pixel resolution of 100 m and shows Ireland's peatland resource to be 0.95 Mha or 13.8% of the national land area. This is comparable to estimates of 13.2% from CORINE land‐cover data (1990s), 17.0% from the Peatland Map of Ireland (1970s), and 16.7% from the General Soil Map (1980s). The derived map depicts the spatial extent of three peatland types: raised bog and low‐ and high‐level blanket bog. Ground truthing of the derived map enabled estimates of pixel reliability to be calculated. The derived map has an overall reliability of 75% compared with the reliability of 65% for CORINE, 58% for the Peatland Map of Ireland, and 50% for the General Soil Map. We concluded that the methodology created a value‐added soil map product from a number of data sources, all of which were to some degree imperfect. The approach taken could be applied to similar survey problems not related to peatlands.
Total Soil Carbon and Water Quality: An Implication for Carbon Sequestration
Authors: Eshel Gil , Fine Pinchas , Singer Michael J.
Published: March 2007

Carbon sequestration in soil has been suggested as a means of reducing the rate of increase of atmospheric CO2Most soil science research has been on soil organic carbon (SOC) sequestration but in arid and semiarid climates, soil inorganic carbon (SIC) may offer another option for C sequestration. A field study was conducted in Bakersfield, CA, to determine if irrigation water quality (fresh water [FW] vs. treated effluent [TE]) affected the distribution and amount of SIC and SOC in the upper 4 m of soil and parent material compared to a nonirrigated (NI) field. Significant carbonate depletions were found in the upper 2 m in both irrigated fields compared with the NI. Differences in carbonate content between irrigated fields were also related to soil texture. Total carbonate and clay‐size carbonate were more abundant at the sites irrigated with TE than at the sites irrigated with FW, indicating that the TE had inhibited carbonate dissolution. Based on stable isotope analyses (13C and18O) and radiocarbon dating, we estimated that irrigation for >75 yr sequestered about 7.15 kg m−2(4 m)−1of SIC under FW and between 0.9 and 2.4 kg m−2(4 m)−1under TE, if carbonate dissolution is C sequestration. Adding C loss due to SOC decomposition to the SIC sequestration, the fields may be a source for 8.8 and 17.4 to 15.9 kg m−2(4 m)−1of C under FW and TE, respectively. This study provides some of the first evidence of how water quality affects the C budget in an arid region.
Redox Processes in Mangrove Soils under Rhizophora mangle in Relation to Different Environmental Conditions
Authors: Ferreira T. O. , Otero X. L. , Vidal-Torrado P. , Macías F.
Published: March 2007

Pore‐water and solid‐phase analysis was undertaken to study the effects of different environmental conditions on redox processes in mangrove soils on the southern coast of Brazil. Three Rhizophora mangle (L.) mangrove forests were studied in different physiographic positions—riverine, fringe, and basin forest—and substrate compositions. Our results indicate different geochemical conditions in soils from different physiographic positions. In the fringe soils, the low acid‐volatile sulfide and pyrite Fe contents, associated with high values of Fe2+ in pore water, indicate oxic and suboxic conditions in surface layers (0–10 cm). Below this depth, anoxic conditions prevail and sulfate reduction becomes the dominant process of organic matter decay, as indicated by higher concentrations of dissolved HS− and pyrite Fe. In the basin forest, long periods of tidal flooding and low rates of litter export maintained anoxic conditions and high organic matter contents, necessary for anoxic respiration to take place, as shown by the low Fe2+ and HS− concentrations in pore water, along with high degree of Fe pyritization values and high concentrations of pyrite Fe. In the riverine soils, the lowest concentrations of pyrite Fe and the highest concentrations of HS−in pore water were obtained in response to low availability of reactive Fe (0–10cm, 31.8 ± 8.0 mmol kg−1; 20–30 cm, 43.2 ± 32.3 mmol kg−1) due to its sandy texture, which limits pyrite synthesis. Our results indicate that the participation and intensity of each process may vary within different physiographic positions because of the effects on the frequency and duration of tidal flooding and soil composition. Our results also show that R. mangle is present on substrates with different geochemical conditions (oxic, suboxic, and anoxic).
Dissolution of Zinc‐Cadmium Sulfide Solid Solutions in Aerated Aqueous Suspension
Authors: Barrett K. A. , McBride Murray B.
Published: March 2007

Anoxic conditions in Zn‐ and Cd‐contaminated soils and sediments result in the formation of highly insoluble metal sulfides. Little is known, however, about the ability of mixed Zn–Cd sulfides, the most likely solid phases to form in these environments, to persist and limit Zn and Cd solubility under intermittently oxidizing conditions that are common with fluctuating water tables in wet soils. We therefore conducted laboratory experiments to measure the zero‐order rate constants for oxidative dissolution of synthetic solid solutions of Zn–Cd sulfides under aerated conditions, and the release of SO42−, Zn2+, and Cd2+ into solution. It was found that ultrafine synthetic metal sulfide particles with moderately high Zn/Cd mole ratios (≥20) were relatively stable under fully aerated conditions, and oxidized at much slower rates than sulfides with low Zn/Cd ratios. At the same time, high‐Zn sulfides were very efficient at retaining Cd in insoluble form even at very high solid‐phase Cd concentrations (>10000 mg kg−1) and low pH (<5), preferentially releasing Zn into solution. The preferential retention of Cd in sulfide particles with high Zn/Cd ratios was indicated by the persistence of much higher Zn/Cd mole ratios in solution than in the solid as the sulfide suspensions were equilibrated with atmospheric O2 In contrast, Cd‐rich Zn–Cd sulfides were readily oxidized under aerated conditions with the release of high concentrations of both Zn and Cd into solution. We concluded that colloidal Zn–Cd sulfide solid solutions high in Cd would be unlikely to limit the solubility of Cd or Zn to levels that would be nontoxic to soil biota or plants, whereas metal sulfides with high Zn/Cd ratios may be sufficiently persistent to retain Cd in an insoluble form in intermittently aerobic as well as anaerobic heavy‐metal‐contaminated wetlands.
Characterizing Soil Water‐Conducting Macro and Mesoporosity as Influenced by Tillage Using Tension Infiltrometry
Authors: Moret D. , Arrúe J. L.
Published: March 2007

Knowledge of soil water conductive porosity is of paramount importance for understanding the water and solute movement in soil. The objective of this study was to describe and evaluate an alternative pore index, i.e., the representative mean pore radius for two consecutive soil water tensions (λΔΨ), for characterizing the water‐transmitting macro‐ and mesoporosity of soil. The hydraulic conductivity (K) and related hydraulic parameters were measured using a tension disk infiltrometer at −14, −4, −1, and 0 cm water pressure heads at a soil depth of 2 cm on a long‐term conservation tillage experiment (after 9 yr of trial) under conventional tillage (CT), reduced tillage (RT), and no‐tillage (NT) treatments. The soil was loam (Xerollic Calciorthid). The measurements were performed within the first half of a 16‐ to 18‐mo‐long fallow period. Unlike the model based on the classical capillary rise theory, which assumes no differences between measurement sites (e.g., tillage treatments) for the corresponding equivalent pore radius (C0) for macro‐ and mesopores, significant differences in λΔΨ values for macro‐ and mesopores were found between the three tillage systems tested. The number of water‐transmitting macro‐ and mesopores per unit area estimated by means of the capillary rise approach was significantly greater than that calculated using the λΔΨ pore index. Although significantly higher values of λΔΨ for both macro‐ and mesopores were observed under NT, a significantly lower near‐saturation K was found under NT than CT and RT treatments due to the lower density of water‐transmitting macro‐ and mesopores.
Water Retention and Hydraulic Conductivity of Cross‐Linked Polyacrylamides in Sandy Soils
Authors: Bhardwaj A. K. , Shainberg I. , Goldstein D. , Warrington D. N. , J.Levy G.
Published: March 2007

Mixing superabsorbents, such as cross‐linked polyacrylamides (PAM), with sandy soils may decrease water percolation rates and increase water availability to crops. Four polymers were evaluated for their effects on water retention and hydraulic conductivity (HC) in the presence of either tap or distilled water and within sand mixtures. Water retained by the absorbents alone (at low suction) ranged between 200 and 500 kg kg−1 of polymer; water retained by the polymers when mixed with sand ranged between 40 and 140 kg kg−1 Water retained per kilogram of polymer increased with an increase in polymer concentration in the sand while undergoing desorption, but absorbed water decreased with polymer concentration during sorption, indicating an effect of hysteresis and absorption kinetics in the water absorption process. Applying a hydraulic head of tap water initially caused a decrease in the HC, explained by the decrease in the volume of the soil–absorbents mixtures, followed by a steady increase in HC ascribed to drainage of water from the swollen polymer granules that led to an increase in the size of pores available for water flow. Leaching the soil–absorbent mixtures with distilled water, simulating rainwater, increased the volume of the mixtures (due to polymer swelling) and decreased their HC due to pore blockage by the swollen polymer grains. Better understanding of the interaction among absorbents, soil, and water quality may produce an efficient and economic technology for improving the water management of sandy soils.
Organic Amendments Affect Soil Parameters in Two Long‐Term Rice‐Wheat Experiments
Authors: Tirol-Padre A. , Ladha J. K. , Regmi A. P. , Bhandari A. L. , Inubushi K.
Published: March 2007

The impacts of continuous applications of an organic manure (farmyard manure [FYM], green manure [GM], and wheat straw [WS]) combined with inorganic fertilizers (N, P, and K) on soil parameters and productivity of rice (Oryza sativaL.)–wheat (Triticum aestivumL.) systems were investigated in two long‐term experiments under conventional tillage in Ludhiana, India, and Bhairahawa, Nepal. Changes in total and labile soil C and N, and microbiological parameters relative to unfertilized and inorganically fertilized controls were measured. Organic amendments had positive but variable effects. In Ludhiana, FYM application increased total C and N, permanganate‐oxidizable C, and hot‐water‐extractable C (HWEC) by 40 to 70% relative to the control after 20 yr and maintained HWEC and total N with time. In the other treatments, HWEC and total N showed declining trends with time, whereas total C increased by 17% on average. In Bhairahawa, although total organic C and N increased with organic amendments after 15 yr, HWEC did not. Increases in C and N, respectively, as fractions of the applied organic fertilizers were 11 to 23 and 37 to 39% from FYM, 4 to 21 and 19 to 41% from GM, and 3 and 24% from WS. The FYM improved available P, cation exchange capacity, potential mineralizable N, and dehydrogenase activity, but microbial biomass C, basal respiration, flush of CO2after rewetting dried soil, and metabolic quotient remained unchanged. The current practice of inorganic fertilization alone cannot maintain the soil quality needed to sustain crop productivity. Amounts of organic manures to supplement inorganic fertilizers must be optimized to increase C and N accumulations in the soil without negative effects on crop yield.
Hydration Kinetics of Wettable and Water‐Repellent Soils
Authors: Hurrass Julia , Schaumann Gabriele E.
Published: March 2007

The hydration kinetics of soil organic matter (SOM) are influential factors for transport and sorption processes in soil. Nevertheless, our knowledge about wetting and swelling processes, which both control the overall hydration kinetics, is limited. In this study, we observed the hydration process of actually water‐repellent and wettable soil samples by three independent methods. The rate of water uptake by water‐repellent samples was distinctly lower than that of wettable samples when the water was supplied in the liquid phase, but was comparable when water was supplied in the gas phase. Gravimetric measurements of the water uptake and 1H nuclear magnetic resonance relaxometry showed that wetting of water‐repellent soils may last up to 3 wk. This duration is distinctly longer than the water drop penetration time of the samples, which consequently only reflects the first wetting step of the soil surface and does not consider infiltration of larger amounts of water. Since the achievement of equilibrium conditions is a slow process, the hydration kinetics of SOM may control transport and sorption kinetics in water‐repellent soils. Differences in the freezing, melting, and evaporation processes of soil water of actually water‐repellent and wettable soil samples, observed by differential scanning calorimetry (DSC), are probably only a consequence of different water contents under field conditions. Consequently, the DSC measurements provided no evidence of a general difference in the way water binds in water‐repellent and wettable soil samples.
Comparing Unsaturated Colloid Transport through Columns with Differing Sampling Systems
Authors: Ilg Katrin , Ferber Eckhard , Stoffregen Heiner , Winkler Andreas , Pekdeger Asaf , Kaupenjohann Martin , Siemens Jan
Published: March 2007

Methodological difficulties of colloid sampling in the vadose zone are limiting our knowledge regarding the relevance of colloid transport for groundwater contamination. We compared the colloid sampling efficiency of five different lysimeters in a column experiment (9 cm length, 8 cm diameter) using 59Fe‐labeled goethite: polyester membranes with a pore diameter of (i) 1.2 μm and (ii) 10 μm, (iii) porous glass plates with 16‐μm pore diameter, (iv) wick samplers, and (v) zero‐tension lysimeters. Four replications of each lysimeter type were tested with concentrations of 0.1 and 10 mg L−1 goethite. The irrigation rate was 58 mm h−1, which caused an average transport velocity of 240 mm h−1 Compared with NO3−, a tendency of accelerated transport of goethite in the sand columns was observed. The mean recovery of 59Fe for all lysimeters was 30.7 ± 6.7% for the small and 3.4 ± 3.5% for the large colloid input concentration. For the small goethite concentration, no differences between lysimeter systems were detected. In contrast, the lysimeters performed differently at large concentrations: zero‐tension and 10‐μm membrane lysimeters showed the largest (9.1 and 6.8%), wick lysimeters the smallest colloid recovery (0.7%), which was related to trapping of colloids in the wick. We conclude that membranes of 10‐μm pore size and zero‐tension lysimeters are superior for colloid sampling, but the results of the latter may be biased toward an overestimation of colloid transport because of water saturation at the lysimeter–soil interface.
Theoretical Solid/Solution Ratio Effects on Adsorption and Transport: Uranium(VI) and Carbonate
Authors: Phillippi John M. , Loganathan Vijay A. , McIndoe Melissa J. , Barnett Mark O. , Clement T. Prabhakar , Roden Eric E.
Published: March 2007

The reactive transport of metal and radionuclide contaminants in the subsurface often significantly influences their long‐term fate and effect in the environment. Typically, predictions of contaminant migration at a site involve the measurement of a distribution coefficient (KD), which is used to describe the interactions between the contaminant and the subsurface. The typical implicit assumption is that the adsorption isotherm (e.g., KD) is independent of the solid/solution ratio. Many geochemical factors, however, play a significant role in the reactive transport of contaminants in groundwater. The adsorption and transport of U(VI), for example, is strongly influenced by the presence of Fe oxyhydroxides and the carbonate system. However, these solutes or adsorbates and adsorbent interact with one another in a complex and highly nonlinear manner. Modeling of U(VI) adsorption has shown that under certain conditions, the solid/solution ratio can theoretically have a significant impact on the U(VI) adsorption isotherm. In particular, combining strongly interacting solutes [U(VI) and carbonate] and adsorbents [Fe(III) oxyhydroxides] that have monocomponent solute or adsorbate adsorption isotherms that are independent of the solid/solution ratio results in a multicomponent system where adsorption isotherms become dependent on the solid/solution ratio. The solid/solution ratio can therefore be critical when extrapolating the results of batch experiments, generally conducted at low solid/solution ratios, to column experiments and then to the field. These results have implications for modeling, scaling, and predicting the reactive transport of U(VI) and other strongly interacting solutes (e.g., metals and dissolved organic C) in subsurface environments.
Macronutrient Depletion and Redistribution in Soils under Conifer and Northern Hardwood Forests
Authors: Schroth Andrew W. , Friedland Andrew J. , Bostick Benjamin C.
Published: March 2007

While potentially important in the context of global biogeochemical change, the influence of different forest communities on chemical weathering rates in soils is poorly understood. We investigated the influence of four forest types (northern hardwood vs. three conifer plantations) on base cation depletion and redistribution in soils at Marsh–Billings–Rockefeller National Historical Park (MBRNHP) on 100‐yr forest development time scales. This site was ideal for the examination of forest‐type influence on the chemical denudation of the landscape during soil development due to a unique forest management history. Soils at MBRNHP are mildly acidic and developed on a silicate‐rich parent material with trace carbonates. Soil composition beneath different forest types indicates significant depth‐dependent differences in cation depletion. Conifer forest surface soils were more acidic and depleted in mineral‐phase base cations than those under northern hardwood forests. This was presumably due to aggressive weathering agents produced by fine‐root exudation and organic matter decomposition in conifer forest surface soils. At depth, there was a more acidic and sometimes cation‐depleted soil profile under northern hardwood relative to conifer forests, which could be associated with deeper root networks of northern hardwood species and related high nutrient demands, proton release, and mechanical weathering of deep soil. Depth‐dependent trends were more evident with Ca and Mg depletion profiles than Na and K, suggesting that vegetative enhancement of the weathering environment was most effective in dissolving more pedogenically reactive divalent cation mineral phases. This model of forest‐type enhancement of chemical weathering has important ramifications in the context of global biogeochemical change and forest management.
A Review of the Use of the Basic Cation Saturation Ratio and the “Ideal” Soil
Authors: Kopittke Peter M. , Menzies Neal W.
Published: March 2007

The use of “balanced” Ca, Mg, and K ratios, as prescribed by the basic cation saturation ratio (BCSR) concept, is still used by some private soil‐testing laboratories for the interpretation of soil analytical data. This review examines the suitability of the BCSR concept as a method for the interpretation of soil analytical data. According to the BCSR concept, maximum plant growth will be achieved only when the soil's exchangeable Ca, Mg, and K concentrations are approximately 65% Ca, 10% Mg, and 5% K (termed the ideal soil). This “ideal soil” was originally proposed by Firman Bear and coworkers in New Jersey during the 1940s as a method of reducing luxury K uptake by alfalfa (Medicago sativa L.). At about the same time, William Albrecht, working in Missouri, concluded through his own investigations that plants require a soil with a high Ca saturation for optimal growth. While it now appears that several of Albrecht's experiments were fundamentally flawed, the BCSR (“balanced soil”) concept has been widely promoted, suggesting that the prescribed cationic ratios provide optimum chemical, physical, and biological soil properties. Our examination of data from numerous studies (particularly those of Albrecht and Bear themselves) would suggest that, within the ranges commonly found in soils, the chemical, physical, and biological fertility of a soil is generally not influenced by the ratios of Ca, Mg, and K. The data do not support the claims of the BCSR, and continued promotion of the BCSR will result in the inefficient use of resources in agriculture and horticulture.
Low Dissolved Organic Carbon Input from Fresh Litter to Deep Mineral Soils
Authors: Fröberg M. , Jardine P. M. , Hanson P. J. , Swanston C. W. , Todd D. E. , Tarver J. R. , Garten C. T.
Published: March 2007

Dissolved organic carbon (DOC) leached from recent litter in the forest floor has been suggested to be an important source of C to the mineral soil of forest ecosystems. To determine the rate at which this flux of C occurs, we have taken advantage of a local release of 14C at Oak Ridge National Laboratory Reservation, Oak Ridge, TN (35°58′N, 84°16′W). Eight replicate 7‐ by 7‐m plots were established at four field sites on the reservation in an upland oak forest setting. Half of the plots were provided with 14C‐enriched litter (Δ14C ≈ 1000‰), and the other half with near‐background litter (Δ14C ≈ 220‰) for multiple years. Differences in the labeled leaf litter were used to quantify the movement of litter‐derived DOC through the soil profile. Soil solutions were collected for several years with tension lysimeters at 15‐ and 70‐cm depths and measured for DOC concentration and 14C abundance. The net amount of DOC retained between 15 and 70 cm was between 2 and 10 g m−2 yr−1 There were significant effects of the litter additions on the 14C abundance in the DOC, but the net transport of 14C from the added litter was small. The difference in Δ14C between the treatments with enriched and near‐background litter was only about 130‰ at both depths, which is small compared with the difference in Δ14C in the added litter. The primary source of DOC within the mineral soil must therefore have been either the Oe or Oa horizon or the organic matter in the mineral soil. During a 2‐yr time frame, leaching of DOC from recent litter did not have a major impact on the C stock in the mineral soil below 15 cm in this ecosystem.
Modeling Soil Carbon and Nitrogen Dynamics in No‐till and Conventional Tillage Using PASTIS Model
Authors: Oorts Katrien , Garnier P. , Findeling A. , Mary B. , Richard G. , Nicolardot B.
Published: March 2007

The performance of the PASTIS model was evaluated to simulate soil C and N fluxes under real field conditions with conventional moldboard plowing (CT) and no‐tillage (NT) systems differentiated for 33 yr for a loamy soil in northern France. Afterward, the influences on the C and N fluxes by soil temperature, soil water content, and quantity and localization of soil organic matter (SOM) and crop residues in the soil profile were determined. The model PASTIS was able to provide good simulations for the dynamics of soil water content and temperature, CO2 emissions, residue decomposition, and N mineralization. Simulation showed that the presence of the mulch layer in NT reduced cumulative total water evaporation and increased water drainage at the bottom of the 25‐cm depth. Furthermore, simulation showed that the larger cumulative total CO2 flux in NT resulted from larger CO2 emissions as a product of crop residue decomposition and not as product of SOM decomposition. The larger amount of accumulated residues of previous crops in NT more than compensated for the slower residue decomposition rate of surface compared with incorporated residues. It was the water content of the surface crop residues that largely controlled the magnitude of this difference in decomposition rate of the crop residues between CT and NT. This means that, besides the amount of crop residues in both tillage systems, the distribution of rainfall and potential evaporation have a large influence on the differences in C and N fluxes between the two tillage systems
In Situ Characterization of Soil Clay Content with Visible Near‐Infrared Diffuse Reflectance Spectroscopy
Authors: Waiser Travis H. , Morgan Cristine L. S. , Brown David J. , Hallmark C. Tom
Published: March 2007

Visible and near‐infrared (VNIR, 400–2500 nm) diffuse reflectance spectroscopy (DRS) is a rapid, proximal‐sensing method that has proven useful in quantifying constituents of dried and ground soil samples. Very little is known, however, about how DRS performs in a field setting on soils scanned in situ. The overall goal of this research was to evaluate the feasibility of VNIR‐DRS for in situ quantification of clay content of soil from a variety of parent materials. Seventy‐two soil cores were obtained from six fields in Erath and Comanche counties, Texas. Each soil core was scanned with a visible near‐infrared spectrometer, with a spectral range of 350 to 2500 nm, at four different combinations of moisture content and pretreatment: field‐moist in situ, air‐dried in situ, field‐moist smeared in situ, and air‐dried ground. The VNIR spectra were used to predict total and fine clay content of the soil using partial least squares (PLS) regression. The PLS model was validated with 30% of the original soil cores that were randomly selected and not used in the calibration model. The validation clay predictions had a root mean squared deviation (RMSD) of 61 and 41 g kg−1 dry soil for the field‐moist and air‐dried in situ cores, respectively. The RMSD of the air‐dry ground samples was between the two in situ RMSDs and comparable to values in the literature. Smearing the samples increased the field‐moist in situ RMSD to 74 g kg−1 Whole‐field holdout validation results showed that soils from all parent materials need to be represented in the calibration samples for maximum predictability. In summary, DRS is an acceptable technique for rapidly measuring soil clay content in situ for various water contents and parent materials.
Carbon Storage in the Soils of a Mesotidal Gulf of Maine Estuary
Authors: Jespersen J. L. , Osher L. J.
Published: March 2007

Estuaries have the highest primary productivity of all ecosystems, yet the soils in estuarine environments have been largely overlooked in C sequestration studies. This research quantified organic C stored in the top 1 m of soils from the Taunton Bay estuary in Hancock County, Maine. Taunton Bay is centrally located within Maine's Island–Bay Coastal Complex, a physiographic region that encompasses 47% of the state's coastline. Riverine inputs of sediments and sediment‐associated organic matter to this and most Maine estuaries are quite low. These estuary soils form by incremental additions of reworked glaciofluvial marine sediments and estuarine organic matter to the soil surface. The organics are protected from decomposition by anaerobic conditions. As sea level rises, the estuary area increases by inundating and submerging the soils at its edges. The average concentration of soil organic C in the top 1 m of these estuary soils is 2.4% and the average soil bulk density is 0.67 g cm−3 The organic C content is 136 Mg C ha−1, which is greater than the C content in the top 1 m of Maine's upland soils. These results suggest that systematically quantifying and dating the C in estuarine soils will provide valuable data for use in regional and global C budgets and climate models.
Transient Response Simulation of an Off-Road Motorcycle with Conventional and Multicell Tire Inflation Mechanisms
Authors: Richards Christopher M. , Summers Thomas Wade
Published: March 2007

Resistance to complete loss of inflation pressure due to puncture is the primary purpose for using nonconventional multicell tire inflation mechanisms. However, recent subjective testing of one particular multicell mechanism also reveals beneficial ride performance characteristics. To gain scientific understanding of this additional benefit, an off-road motorcycle model is developed. Pneumatic stiffness behavior of a conventional inner-tube and the multicell inflation mechanism is described by a simplified tire model which has been shown to accurately predict experimentally measured static stiffness data. Numerically simulated transient response data from the vehicle model is used to evaluate ride performance characteristics when the two mechanisms are used for tire inflation. Data analysis is also performed to reveal why performance improves when the multicell mechanism is utilized. The procedure is validated using experimental data collected on a real vehicle under conditions similar to the numerical simulation.
The Impact of Plus-Sized Wheel/Tire Fitment on Vehicle Stability
Authors: Daws J. W. , Larson R. E. , Brown J. C.
Published: March 2007

Plus-sizing in the tire industry is the growing practice of replacing a vehicle’s original equipment wheel size with a larger diameter wheel and replacing the tire with a lower-aspect-ratio tire of the same diameter. This practice is normally associated with aftermarket sales, and there is a growing trend for vehicle dealerships to fit these larger wheels/tires to new cars. This paper discusses the general practice and its effect on some of the performance characteristics of vehicles. A vehicle taken from the NHTSA New Car Assessment Program’s rollover “Star” rating program is used to illustrate the impact of plus sizing on static stability. Some of the dynamic tire effects that could influence vehicle stability are discussed, and preliminary testing data on the dynamic impact of plus sizing are presented.
Measuring Lateral Tire Performance on Winter Surfaces
Authors: Phetteplace G. , Shoop S. , Slagle T.
Published: March 2007

The Army has approved and funded an Army Technology Objective (ATO) entitled “High Fidelity Ground Platform and Terrain Mechanic Modeling.” This ATO is being jointly performed by the Engineer Research and Development Center (ERDC) along with the U.S. Army Tank Automotive Research, Development and Engineering Center (TARDEC) and the Army Research Laboratory (ARL). Two of the ERDC laboratories are participating in the ATO: The Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, NH, and the Geotechnical and Structures Laboratory in Vicksburg, MS. One of CRREL’s major milestones for the ATO is to extend two-dimensional ground contact models for the TARDEC Real-time Simulator to full three-dimensional functionality by including the lateral forces. Central to that requirement is an understanding of lateral forces on all-seasons terrain. While modeling of vehicle tire lateral force interactions for typical hard paved surfaces is well understood, there is a need to translate that understanding in a consistent manner into off-road terrain and low-friction surfaces. The experimental work described in this paper is fundamental to gaining the required understanding. The experimental work, performed with instrumented vehicles, was accomplished via a contract with the Nevada Automotive Test Center. The testing included both lateral and longitudinal traction tests on winter surfaces. The surfaces included ice, packed snow, and disaggregated snow. The two principal tires tested were an all-season LT235/75R15 that has been the subject of many tests on the CRREL instrumented vehicle, and a tire used on the military’s HMMWV, size 37×12.50R16.5. For each tire and surface, tests at a minimum of two inflation pressures were conducted. For each surface/tire/inflation variant a minimum of ten replicate data sets were obtained. This paper reports the results of the tests and the analysis conducted to date.
Effect of Pre-treatment with Inhaled Furosemide on Allergen Nasal Challenge
Authors: Nucera Eleonora , Schiavino Domenico , Milani Alessandro , Patriarca Giampiero
Published: March 2007

The inhalation of furosemide has been reported to inhibit the bronchospasm induced by several agents. In the present study, we evaluated the effect of inhaled furosemide on the specific nasal challenge test in patients with allergic rhinitis. A total of 21 consecutive patients with allergic rhinitis (positive skin test and RAST) and a positive based nasal provocation test (NPT) with the specific allergen were investigated. In each patient, we compared the changes in nasal air-flow (anterior rhinomanometry) during NPT after inhalation of placebo and 20 mg furosemide. The previously positive NPT response to the inhalation of the specific allergen became negative after the furosemide pretreatment in 16 patients (76.2%, p < 0.001, chi-square test). The nasal air flows during NPT were significantly increased after furosemide treatment with respect to placebo inhalation (F = 17.2, d.f. = 1 and 3; p < 0.03; covariance analysis). Our results suggest that the pretreatment with inhaled furosemide in atopic subjects is able to exert a protective effect on the nasal mucosa reactivity to the specific allergen. Therefore, the anti-reactive effect of the drug on the airways is not confined to the bronchial asthmatic response.
Endoscopic Lothrop Procedure: The University of Miami Experience
Authors: Casiano Roy R. , Livingston Jeffrey A.
Published: March 2007

Over a 2-year period, 21 patients with clinical and radiologic evidence of persistent or recurrent frontal sinusitis who had a prior ethmoidectomy and/or frontal sinusotomy underwent an endoscopic Lothrop procedure. The patients’ chief complaints were headaches (13), nasal obstruction and/or purulent rhinorrhea (4), orbital abscess/cellulitis (2), anosmia (1), and cough (1). Preoperative frontal headaches were present in 19 patients.

The common frontal ostium remained patent (>50% of intraoperative size) by flexible fiberoptic examination and transillumination 2–24 months postoperatively in 12 of 21 patients (57%). Eighteen of 21 patients (86%) had improved or resolved chief complaints. All but 4 of 19 patients (21%) with preoperative frontal headaches had improved or resolved symptoms. Two patients required additional surgery during the follow-up period. The endoscopic Lothrop procedure is a viable option before frontal sinus obliteration in patients with recurring frontal sinusitis who have failed conventional endoscopic techniques. The surgical technique and results will be presented.