bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Growth Stage on Soybean Response to Chronic Ozone Exposure
Authors: Heagle Allen S. , Miller Joseph E. , Rawlings John O. , Vozzo Steven F. 
Published: July 2010

AbstractFour cultivars of soybean [Glycine max (L.) Merr., cv. Forrest, Davis, Bragg, and Ransom] were exposed to chronic doses of O3 in open‐top field chambers to determine if a relationship exists between growth stage and yield response to O3. The season was divided into four 31‐d quarters (Q1–Q4) in which plants were exposed either to charcoal‐filtered air (C) or to nonfiltered air with O3 added (N). Sixteen different quarterly sequences represented all possible combinations of the C and N treatments. The mean 31‐d O3 concentration (7 h d−1 mean) in the N treatment was almost identical at 96 to 98 nL L−1 (ppb) for each quarter. In the sequence with N during all four quarters (NNNN), plants were exposed from emergence to physiological maturity. Mean yields in the NNNN treatment, expressed as a percentage of yield in the CCCC treatment ranged from 44% for Forrest (56% loss) to 70% for Bragg (30% loss). Ozone exposure during mid‐ to late‐growth stages generally caused a greater yield decrease than exposure during early growth stages. Models to estimate O3‐yield relationships were developed separately for each cultivar using seasonal and quarterly O3 statistics. A statistical comparison for relative goodness‐of‐fit between these two models was not possible. However, the models based on the quarterly O3 values provided estimates with less absolute deviation from the observed data than models based on seasonal O3 values. Models based on quarterly O3 values generally confirmed that the relative effect of O3 during a given quarter was related to when the pod‐fill stage occurred. For example, with the early‐maturing Forrest, pod fill occurred mainly during Q3 so O3 stress during Q3 had the greatest effect. For the later‐maturing Bragg, pod fill occurred mainly during Q4 so O3 stress during Q4 had the greatest effect.
Agronomic Effectiveness of Wood Ash as a Source of Phosphorus and Potassium
Authors: Erich M. Susan 
Published: July 2010

AbstractWood ash is a residual material produced when wood is burned for energy production. It is a useful soil amendment because it raises soil pH and has the potential to supply plant nutrients. The two studies described in this paper were designed to assess the plant availability of P and K in wood ash. Both studies compared nutrient uptake by corn (Zea mays L.) grown in the greenhouse in wood ash—amended soils to nutrient uptake from fertilizer‐amended soils. The wood ashes used were chemically characterized for available P and soluble K content by ammonium citrate extraction, as well as for total P and K. In addition wood ash‐ and fertilizer‐amended soils from the P availability study were extracted with Bray‐1, Olsen, and NH4OAc solutions after harvest. Wood ashes were found to be more similar to conventional P fertilizer materials when the amendments were compared on a citrate‐extractable P basis than when they were compared on a total P basis. For K there was little difference between ash and fertilizer sources, whether they were compared on a total K or a citrate‐extractable K basis. The buffered NH4OAc (pH 3.0) extract was adequate for determining K availability in wood ash—amended soils, but inadequate with regard to P availability in these soils. The buffered solution may have dissolved residual wood ash and released P that was not actually plant‐available. Either the Bray‐1 or the Olsen extract provided a relative measure of P availability that was consistent for both fertilizer‐ and wood ash—amended soils.
Growth and Elemental Content of Two Tree Species Growing on Abandoned Coal Fly Ash Basins
Authors: Carlson Claire L. , Adriano Domy C. 
Published: July 2010

AbstractDifferences in aboveground tissue concentrations of trace elements were assessed for sweetgum (Liquidambar styraciflua L.) and sycamore (Platanus occidentalis L.) growing on two abandoned coal fly ash basins and a control soil (Fuquay sand; loamy, siliceous, thermic Arenic Plinthic Kandiudult; pH = 4.99). The “wet basin” (pH = 5.58) had originally received precipitator ash in an ash‐water slurry, while the “dry basin” (pH = 8.26) had received both precipitator and bottom ash in dry form. In general, trees from the wet basin exhibited elevated trace element concentrations in comparison to the controls, while the dry basin trees exhibited reduced concentrations. One of the most striking differences in elemental concentrations among the ash basin and control trees was observed for Mn, with the control trees exhibiting concentrations orders of magnitude greater than the ash basin trees. Differences in foliar trace element concentrations among the sites can generally be explained by differences in substrate trace element concentrations and/or substrate pH. While trees from the wet ash basin generally had the highest trace element concentrations, these trees also attained the greatest height and diameter growth, suggesting that the elevated trace element concentrations in the wet basin substrate are not limiting the establishment of these two species. The greater height and diameter growth of the wet basin trees is presumably a result of the greater water‐holding capacity of the substrate on this site. Differences in growth and tissue concentrations between sweetgum and sycamore highlight the importance of using more than one species when assessing metal toxicity or deficiency on a given substrate.
A Simple Effects Analysis of the Effects of Phosphogypsum Application on Phosphorus Transport to Runoff Water and Eroded Soil Sediments
Authors: Korentajer L. , Henry P. C. , Eisenberg B. E. 
Published: July 2010

AbstractPhosphorus contamination of surface waters as a result of land application of phosphogypsum (PG—a soil amendment containing orthophosphate‐P) has not yet been investigated. A laboratory rainfall simulator study was conducted to assess the initial and residual effects of PG application on P transport to runoff water and eroded soil sediments. The experiment was carried out using three soils of various dispersivity and four rates of PG application (0, 2, 5, and 10 Mg ha−1, in three replicates). Simulated rainfall was applied during three consecutive wet‐dry cycles consisting of a 1‐h rainfall event followed by a 4‐ to 6‐d drying period. A split‐plot design was used, consisting of soils and rates of PG application as the main plot treatments, and the storm as the split‐plot treatment. A simple effects analysis was used to interpret the interactive effects between storms, PG rate, and soils. The beneficial effects of PG in reducing the amounts of runoff and sediment yield depended on the soil dispersivity. In a highly dispersive soil the positive effect was apparent at the lower rates of application (<5 Mg ha−1) and gradually leveled off at the higher application rates. Conversely, on a soil with low dispersivity the beneficial effect of PG was obtained only at the higher rates of application (>5 Mg ha−1). Differences in response to the PG application were explained in terms of the complementary effects of PG on chemical dispersion and mulching. The effects of PG decreased in subsequent storms indicating a progressive removal of PG from the soil surface by runoff and downward percolation. The orthophosphate‐P concentrations in the runoff were generally much greater than 0.025 mg L−1, which is considered as the threshold concentration limiting algae proliferation in surface waters. Phosphorus removal by runoff and erosion gradually decreased in subsequent storms. The data indicated that P experts were determined by the combined effect of PG rate on the amounts of labile P available for transport, and its effects on the amounts of runoff and sediment yield. The results of the study suggesthat application of high PG rates may resalt in P being exported to the waterways adjacent to the site of application and hence it may contribute to the enhanced eutrophication of the waterways.
Cellulose Decay in Natural and Disturbed Peatlands in North Carolina
Authors: Bridgham Scott D. , Richardson Curtis J. , Maltby Edward , Faulkner Stephen P. 
Published: July 2010

AbstractCarbon cycling is central to nutrient dynamics and accretion rates in wetlands. Drainage and conversion of wetlands has been occurring at an accelerating rate. This paper compares decay rates in natural and disturbed peatlands in the southeastern USA and examines relationships between edaphic factors and decay rates. Cellulose decay rates (as tensile strength loss of cotton fibers) were used to compare decomposition potentials in these peatlands. A 1984 pilot experiment included undisturbed short pocosin and several sites under various stages of agricultural conversion. A spring 1987 experiment included an increasing nutrient availability gradient in undisturbed communities from short pocosin to tall pocosin to gum swamp, drained pocosin with natural vegetation remaining, and pocosin converted to pine forestry and agriculture. In the 1984 experiment, disturbed sites had decay rates approximately nine times greater than undisturbed pocosin. In the 1987 experiment, disturbed sites had decay rates from 1.8 to 10.3 times natural sites. The greatest decay rates occurred in the agricultural site with its high nutrients, less acidic conditions, and relatively low soil moisture. Drained pocosin had the next highest decay rates, although pH and nutrients were low. Pine (Pinus taeda L.) forestry had intermediate rates of decay, while undisturbed sites had low rates. The more nutrient‐rich, but wet and low pH, gum swamp site had similar or slightly higher rates than the pocosin sites. Drainage, relieving excessive soil moisture and the resultant anaerobiosis, was the dominant factor explaining the greater decay rates in the disturbed sites. Other factors, such as nutrient availability and low pH, may have had secondary effects on cellulose decay. Rates were also compared to a global data set based on potential evapotranspiration. Natural sites have rates very close to those predicted, while disturbed sites have much higher rates (1.9–4.4 × predicted).
Estimating Nutrient Exports to Estuaries
Authors: Frink Charles R. 
Published: July 2010

AbstractNutrient export coefficients for Long Island Sound were estimated by relating measured concentrations of N and P in 33 Connecticut lakes to land use in their watersheds. This approach does not require that watersheds represent a single category of land use, but rather uses the lake to integrate contributions from all sources. These estimates were then compared with those obtained from an extensive review of the literature. The results suggest that current models with a sediment transport component tend to overestimate N and P exports from agricultural land and underestimate exports of N and P from wooded and urban land. These differences are likely attributable to greater transport of nutrients in the soluble phase than predicted by such models. Moreover, efforts to reduce erosion may not be effective in preventing losses of nutrients, particularly N, where increased infiltration may actually increase N exports. In conclusion, it appears that more emphasis should be placed on management strategies to reduce leaching losses of N, with less emphasis on structural practices to reduce erosion.
Can Aquatic Macrophytes Mobilize Technetium by Oxidizing Their Rhizosphere?
Authors: Sheppard S.C. , Evenden W.G. 
Published: July 2010

AbstractTechnetium (Tc) is very mobile in aerated surface environments, but is essentially immobile and biologically unavailable in anaerobic sediments. Aquatic macrophyte roots penetrate anaerobic sediments, carrying O2 downward and frequently creating oxidizing conditions in their rhizosphere. We hypothesized that this process could mobilize otherwise unavailable Tc, possibly leading to incorporation of Tc into human or animal foods. Through experiments with rice (Oryza sativa L.), and with a novel artificial macrophyte root, we concluded that this pathway is unlikely to be important for annual plants, especially in soils with a high biological oxygen demand. The relatively slow oxidation of Tc limited its mobilization by short‐lived root systems.
Fate of Heavy Metals in an Abandoned Lead‐Zinc Tailings Pond: II. Sediment
Authors: Sidle Roy C. , Chambers Jeanne C. , Amacher Michael C. 
Published: July 2010

AbstractDistribution of Cu, Zn, Cd, and Pb in sediments within a 14‐ha‐abandoned, Pb‐Zn tailings pond in north central New Mexico was investigated. Tailings were higher in heavy metals and fines in the south portion of the pond largely related to depositional patterns. Metals concentrations in surface deposits (above tailings) decreased across the pond from east to west, probably due to fluvial processes, surface disturbance by offroad vehicles, and surface erosion deposits. The two wet meadow soil/vegetation types at the south end of the pond had higher levels of heavy metals in surface soil and subsoil than the more xeric soil/vegetation types in the mid‐ to upper (north) portions of the pond. Ratios of total Cu, Zn, Cd, and Pb concentrations in surface soils to underlying and surface tailings, and ratios comparing the south and north portions of the pond, indicate that the relative order of mobility is Cd > Zn > Cu > Pb. Although chemical processes are partly controlling the distribution of metals within the pond, fluvial processes are at least as important. The amount and distribution of extractable metals in surface deposits overlying tailings can be used to determine topsoiling requirements for revegetation of the south end of the pond. The distribution of total metals in the upper 1.5 m of the pond suggests that surface water should be routed around the east side of the pond to prevent erosion of contaminated deposits and pollution of groundwater.
Soil Adsorption of Neutral and Anionic Forms of a Sulfonamide Herbicide, Flumetsulam
Authors: Fontaine D. D. , Lehmann R. G. , Miller J. R. 
Published: July 2010

AbstractThe binding of a weakly acidic herbicide (N‐2, 6‐difluorophenyl‐5‐methyl‐1,2,4‐triazolo(1,5a)pyrimidine‐2‐sulfonamide) to soil is presented as an ionization of the weak acid in solution, and the partitioning of both the anionic and neutral forms of the compound into the soil organic matter. This theoretical description is combined with experimentally determined bulk adsorption constants to give the organic C adsorption constants (Koc) for neutral (650 ± 40 L kg–1) and anionic (12 ± 1 L kg–1) forms of the molecule. Additional experiments with four soils adjusted to different pH levels gave an average Koc of 750 L kg±1 for the neutral form. Describing the soil sorption as a combination of anionic and neutral forms provided an adequate description of the measured sorption.
Laboratory Weathering of Combusted Oil Shale
Authors: Essington M. E. 
Published: July 2010

AbstractProper management of large volumes of spent oil shale requires an understanding of disposal environment chemistry and mineralogy. Laboratory weathering is one method to rapidly and inexpensively assess the long‐term potential for spent oil shales to degrade the environment. The objective of this study was to examine the mineralogy and leachate chemistry of three combusted oil shales (two Green River Formation and one New Albany) in a laboratory weathering environment using the humidity cell technique. The mineralogy of the combusted western oil shales (Green River Formation) is process dependent. In general, processing resulted in the formation of anhydrite, lime, periclase, and hematite. During the initial stages of weathering, lime, periclase, and anhydrite dissolve and ettringite precipitates. The initial leachates are highly alkaline (pH > 10.5), saline, and dominated by Na, hydroxide, and SO4. As weathering continues, ettringite dissolves, gypsum and calcite precipitate, and the leachates are dominated by Mg, SO4, and CO3. Leachate pH is rapidly reduced to between 8.5 and 9 with leaching. The combusted eastern oil shale (New Albany) is composed of quartz, illite, hematite, and orthoclase. Weathering results in the precipitation of gypsum. The combusted eastern oil shale did not display a potential to produce acid drainage. Leachate chemistry was dominated by Ca and SO4. Element concentrations continually decreased with weathering. In a western disposal environment receiving minimal atmospheric precipitation, spent oil shale will remain in the initial stages of weathering, and highly alkaline and saline conditions will dominate leachate chemistry. In an eastern disposal environment, soluble salts will be rapidly removed from the spent oil shale to potentially affect the surrounding environment.
Treatment of Four Biorefractory Contaminants in Soils Using Catalyzed Hydrogen Peroxide
Authors: Tyre Bryan W. , Watts Richard J. , Miller Glenn C. 
Published: July 2010

AbstractThe treatment of soil contaminated with pentachlorophenol, trifluralin [2,6‐dinitro‐N, N‐dipropyl‐4‐(trifluoromethyl) benzenamine], hexadecane, and dieldrin (3,4,5,6,9,9‐hexachloro‐1a,2,2a,3,6,6a,7,7a‐octahydro‐2,7:3,6‐dimethanonaphth[2,3‐b]oxirene) using catalyzed hydrogen peroxide [H202 and iron(II)] was investigated in a soil of low development with organic C ranging from 2000 mg kg–1 to 16 000 mg kg–1. Soil treatment was conducted at pH 3 with 240 and 400 mg L–1 iron additions and 120 000 mg L–1 H2O2. Pentachlorophenol and trifluralin degradation rates decreased as a function of soil organic C content. However, soil organic C had no effect on the degradation rates of dieldrin and hexadecane. In addition, the four contaminants degraded at equal rates with soil containing organic C > 10 000 mg kg–1. The ratio of first‐order rate constants for contaminant degradation to hydrogen peroxide consumption (kcontaminant/kh2O2) was used as an empirical measure of treatment efficiency. These ratios were sensitive to both the soil organic C content and to the concentration of iron added during treatment. The efficiency ratios were highest for treatment with no iron addition; these data suggest that iron minerals and H2O2 provide a system in which Fenton‐like oxidations are catalyzed. The ability of iron minerals and H2O2 to oxidize pentachlorophenol was evaluated in goethite‐, hematite‐, and magnetite‐silica sand at pH 3. Pentachlorophenol was degraded in the mineral‐silica sand systems, which was verified by the loss of organic C and the stoichiometric recovery of chloride.
Predicting Nitrate Formation from Soil, Fertilizer, Crop Residue, and Sludge with Thermal Units
Authors: Honeycutt C. W. , Potaro L. J. , Halteman W. A. 
Published: July 2010

AbstractImproved N utilization efficiency is a logical goal for reducing ground and surface water NO–3 contamination associated with various agricultural practices. Providing farmers with a tool for predicting NO–3 production from various N sources should allow for improved N utilization efficiency. This study was conducted to determine if soil thermal units (degree days) could be used to predict NO–3 formation from unamended soils and from soils amended with inorganic N, papermiil sludge, and crop residue. Fifteen studies were compiled from the literature where NO–3 formation had been temporally assessed over three or more temperatures. Data were compiled from three countries, nine states, eight soil orders, 38 soil series, and 473 soil × treatment combinations. Wide ranges in NO–3 concentration were found when assessed vs. days, owing to the various temperature treatments. However, this range was dramatically reduced for approximately 95% of the data files examined when NO–3 concentration was plotted vs. degree days. Nitrate concentration × thermal unit relationships were found to be soil‐specific, indicating this relationship should be determined for each soil or group of similar soils. Regression analyses of covariate data suggested that factors such as soil texture, pH, and climate may influence the nitrate × thermal unit relationship. Although the thermal unit approach has its limitations, its ease of calculation and demonstrated predictive capability suggest it may be a valuable tool for improving N utilization efficiency.
Nitrogen Retention in Forest Soils
Authors: Johnson Dale W. 
Published: July 2010

AbstractFactors affecting N retention in both fertilized and natural forest ecosystems are reviewed. Collectively, the literature suggests that current conceptual models describing N competition among heterotrophs, plants, and nitrifiers in the soil may need some modification. Nitrifiers seem to be better competitors for N than previously recognized, especially in situations where N inputs are continuously elevated (such as in polluted sites or with repeated fertilization). The assumption that heterotrophs are the most effective competitors for N may be valid for the short term with relatively low N inputs, but may not hold true over the long term or with high N inputs. The apparent “mining” of N from soils by trees in N‐poor sites suggests that they, rather than heterotrophs, are the most effective long‐term competitors for N in such cases. Nonbiological reactions of N with soil organic matter are known to be a major cause of N immobilization following fertilization and may represent significant competition for N during decomposition in unfertilized sites as well.
A Supplemental Ultraviolet‐B Radiation System for Open‐Top Field Chambers
Authors: Booker F.L. , Fiscus E.L. , Philbeck R.B. , Heagle A.S. , Miller J.E. , Heck W.W. 
Published: July 2010

AbstractStudies suggest that increased ultraviolet‐B (UV‐B) radiation at the earth's surface due to stratospheric ozone (O3) depletion may affect crop production. Current levels of tropospheric O3 are known to decrease crop yields. To assess the combined effects on plants of increased UV‐B radiation and chronic exposure to O3, a commonly used constant‐addition supplemental UV‐B radiation system was modified for use in open‐top field chambers. Lamp banks containing 14 filtered UV‐B‐313 fluorescent lamps were suspended in 33 chambers to which either charcoal‐filtered, nonfiltered, or nonfiltered air plus O3 was added. Lamp banks provided ample levels and distribution of biologically effective UV‐B (UV‐BBE) radiation for stimulating up to a 29% loss of column O3, according to a radiative transfer model. However, ground‐based measurements of solar UV‐BBE radiation provided a more realistic base than the model for simulations of column O3 loss using supplemental UV‐B radiation. Shading by the lamp bank and chamber assembly reduced the daily solar UV‐BBE, UV‐A, and visible irradiances inside the chamber on average by 24% ± 5% compared with ambient levels. Biweekly adjustments of the supplemental UV‐BBE irradiance level and exposure period provided treatments that were proportional to the seasonal trend in solar UV‐BBE radiation. Control of supplemental UV‐BBE irradiance in proportion to solar UV‐BBE irradiance during the day would better simulate the effects of stratospheric O3 depletion. However, the constant‐addition system was a simpler and less expensive method than the proportional‐addition system for examining the relative sensitivity of plants to the combined effects of increased UV‐B radiation and O3 under field conditions.