bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Improved Method For Field Extraction and Laboratory Analysis of Large, Intact Soil Cores
Authors: Tindall James A. , Hemmen K. , Dowd J.F. 
Published: July 2010

AbstractVarious methods have been proposed for the extraction of large, undisturbed soil cores and for subsequent analysis of fluid movement within the cores. The major problems associated with these methods are expense, cumbersome field extraction, and inadequate simulation of unsaturated flow conditions. A field and laboratory procedure is presented that is economical, convenient, and simulates unsaturated and saturated flow without interface flow problems and can be used on a variety of soil types. In the field, a stainless steel core barrel is hydraulically pressed into the soil (30‐cm diam. and 38 cm high), the barrel and core are extracted from the soil, and after the barrel is removed from the core, the core is then wrapped securely with flexible sheet metal and a stainless mesh screen is attached to the bottom of the core for support. In the laboratory the soil core is set atop a porous ceramic plate over which a soil‐diatomaceous earth slurry has been poured to assure good contact between plate and core. A cardboard cylinder (mold) is fastened around the core and the empty space filled with paraffin wax. Soil cores were tested under saturated and unsaturated conditions using a hanging water column for potentials ≤0. Breakthrough curves indicated that no interface flow occurred along the edge of the core. This procedure proved to be reliable for field extraction of large, intact soil cores and for laboratory analysis of solute transport.
Conceptual and Empirical Foundations for Agricultural‐Environmental Policy Analysis
Authors: Antle John M. , Just Richard E. 
Published: July 2010

AbstractThe knowledge base necessary to support informed agricultural‐environmental policy involves many disciplines. This article presents a conceptual framework for agricultural‐environmental policy analysis based on integration of disciplinary knowledge. The framework demonstrates that, with suitably coordinated data collection and research design activities, policy analysis can be conducted on the basis of disciplinary research. In other words, interdisciplinary data collection rather than interdisciplinary research is needed. Current publicly financed data generation efforts could serve agricultural‐environmental policy needs if disciplinary expertise were used to ensure compatibility with disciplinary requirements while coordinating efforts so as to allow data integration for subsequent policy analysis.
Sorption of the Herbicides Atrazine and Metolachlor to Selected Plastics and Silicone Rubber
Authors: Topp Edward , Smith Ward 
Published: July 2010

AbstractThe adsorption of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine) or metolachlor (2‐chloro‐6′‐ethyl‐N‐(2‐methoxy‐1‐methylethyl)acet‐o‐toluidine) to a variety of plastics and silicone rubber was determined. Both herbicides adsorbed rapidly to silicone rubber, Nalgene 180, Tygon R‐3603, and somewhat less rapidly to low‐density polyethylene. Neither of the herbicides was significantly adsorbed by high‐density polyethylene or acrylic plastic. Very little sorbed metolachlor or atrazine was extracted with methanol and acetone from low‐density polyethylene, indicating that the compounds were tightly adsorbed. Radiolabeled atrazine residues slowly desorbed from Nalgene plastic into water with only the parent compound detectable by gas chromatography, indicating that no chemical transformation had taken place. Organic materials used in containers or equipment coming in contact with atrazine or metolachlor should be screened for their interaction with these compounds.
Selenium and Sulfur Relationships in Alfalfa and Soil under Field Conditions, San Joaquin Valley, California
Authors: Severson R. C. , Gough L. P. 
Published: July 2010

AbstractRelationships between total Se and S or soluble SeO4 and SO4 in soils and tissue concentrations in alfalfa (Medicago sativa L.), under field conditions in the San Joaquin Valley of California, suggest that the rate of accumulation of Se in alfalfa may be reduced in areas where high Se and S concentrations in soils were measured. These data suggest that the balance between carbonate and sulfate minerals in soil may have a greater influence on uptake of Se by alfalfa than does the balance of SeO4 and SO4 in soil solution. Soil and alfalfa were sampled from areas representing a wide range in soil Se and S concentrations. Specific sampling locations were selected based on a previous study of Se, S, and other elements where 721 soil samples were collected to map landscape variability and distribution of elements. Six multiple‐linear regression equations were developed between total and/or soluble soil chemical constituents and tissue concentrations of Se in alfalfa. We chose a regression model that accounted for 72% of the variability in alfalfa Se concentrations based on an association of elements in soil (total C, S, Se, and Sr) determined by factor analysis. To prepare a map showing the spatial distribution of estimated alfalfa Se concentrations, the model was applied to the data from the previously collected 721 soil samples. Estimated alfalfa Se concentrations in most of the study area were within a range that is predicted to produce alfalfa with neither Se deficiency nor toxicity when consumed by livestock. A few small areas are predicted to produce alfalfa that potentially would not meet minimum dietary needs of livestock.
Degradation of Perchloroethylene by Fenton's Reagent: Speciation and Pathway
Authors: Leung Solomon W. , Watts Richard J. , Miller Glenn C. 
Published: July 2010

AbstractSilica sand contaminated with perchloroethylene (PCE) was effectively treated by Fenton's reagent. Silica sand contaminated with PCE at 1000 mg/kg was totally mineralized in 3 h by Fenton's reagent with initial concentration of about 2.1 M of H2O2 and 5 mM of FeSO4. Results from gas chromatography‐mass spectroscopy (GC‐MS) revealed that dichloroacetic acid was the sole significant intermediate species generated, and was believed to be the limiting species leading to mineralization. Experimental measurements of chloride and total organic C suggested that total dechlorination was achieved before decarboxylation in the process of mineralization. A degradation pathway of PCE with Fenton's reagent is proposed based on experimental observations and reactions reported in literature. Formic acid is proposed to be the final intermediate species before it is mineralized to CO2. Perchloroethylene and H2O2 followed pseudo first‐order decomposition kinetics and the rate constants were determined to be 1.65/h ± 0.475/h and 0.206/h ± 0.036/h, respectively.
Nutrient Transformations in Sediments as Influenced by Oxygen Supply
Authors: Moore P. A. , Reddy K. R. , Graetz D. A. 
Published: July 2010

AbstractThe oxidation status of sediments greatly affects biogeochemical processes. The objective of this study was to determine the influence of various levels of O2 on nutrient transformations in lake sediments. Decomposition of sediment organic matter was evaluated under varying levels of O2. Bulk sediment samples obtained from a hypereutrophic lake in central Florida were incubated in stirred microcosms at 25°C for 100 d at four O2 levels. The O2 levels were accomplished by bubbling N2 containing 0, 0.2, 2.0, and 20.0% O2 through the stirred suspensions. Redox potential (Eh) measurements indicated that the two highest O2 levels (i.e., 2.0 and 20.0% O2) resulted in oxidizing conditions (Eh > 400 mV), whereas the lowest O2 levels (0 and 0.2% O2) resulted in reduced conditions (Eh < −300 mV). First‐order rate constants calculated based on CO2 evolution were 0.00010, 0.00027, 0.00062, and 0.00068 d−1 for the 0, 0.20, 2.0, and 20.0% O2 levels, respectively. Methane was detected in the sediments incubated under 0 and 0.2% O2 level, with CO2/CH4 ratios of 3.5 and 160, respectively. Accumulation of soluble organic C (SOC) was greater under reduced conditions than oxidized conditions. Ammonium concentrations decreased rapidly in the oxidized treatments, with concurrent increases in NO3‐N concentrations, whereas under reducing conditions NH4‐N concentrations slowly increased. Rates of N mineralization were slightly higher under oxidized conditions. Although the ratio of N mineralized to CO2 evolved was higher at low O2 levels, the amount of N mineralized vs. the sum of C metabolites (CO2 + CH4 + SOC) was relatively constant under all O2 levels (6.7:1). Reducing conditions resulted in a depletion of SO2−4, whereas under oxidizing conditions SO2−4 concentrations increased, probably due to sulfide oxidation. Soluble reactive P concentrations were lower under oxidizing conditions.
Long‐Term Groundwater Quality Changes from a One‐Time Surface Bromide Application
Authors: Owens L. B. , Edwards W. M. 
Published: July 2010

AbstractThe purpose of this experiment was to use a conservative tracer to study the impacts on groundwater quality of a one‐time application of a water soluble chemical. Potassium bromide was applied at a rate of 168 kg Br−/ha to two 1.1‐ha pasture watersheds in east‐central Ohio. The watersheds had well‐drained residual silt loam soils and with slopes of 12 to 25%. A nearly impermeable clay layer under the watersheds created a perched aquifer from which groundwater samples could be taken at developed springs. There were seasonal variations in Br− concentrations in the groundwater and the highest concentrations (9.2 mg/L maximum peak) occurred within 3 yr following the Br− application. Ten years following the Br− application, Br− concentration in the groundwater was still slightly above initial baseline levels. Even with a one‐time application of a soluble chemical constituent on the surface of a small aquifer system, a multiyear impact was produced on the quality of groundwater.
Neutralization of Soil Acidity and Release of Phosphorus and Potassium by Wood Ash
Authors: Ohno Tsutomu 
Published: July 2010

AbstractWood ash is a residual by‐product being produced at an annual rate of 1.5 to 3.0 million t by wood burning power plants in the USA. Currently, much of this ash is being landfilled. Landspreading of wood ash, which is an alternative liming agent, on both agricultural and forest soils is being proposed as a means of disposal that is both environmentally and economically attractive. As with any soil amendment, there is a potential of adverse environmental impact from the landspreading of wood ash. An experiment was conducted to evaluate the initial rate of soil acidity neutralization by wood ash and the release of P and K into suspensions of 10 acid soils. The wood ash had a CaCO3 equivalence of 480 g kg−1. Changes in soil suspension pH, which were used to quantify the rate of acid neutralization by wood ash, and concentrations of P and K of wood ash‐amended soil suspensions were measured at reaction periods ranging from 30 to 300 s. Soil acidity neutralization rates were strongly correlated with soil pH and decreased 41% per unit pH increase in the pH 3.8 to 6.2 range. After the initial release of P into suspension, sorption of released P resulted in decreasing P concentration in the suspension with increasing reaction time for 7 of the 10 soils. Sorption of released P was greater at lower soil pH values, suggesting precipitation as Al and Fe phosphates. In contrast, the solubility of wood ash K was very high. The increase of suspension K levels resulted from the release of wood ash K as well as from the displacement of K on soil exchange sites by Ca and other exchangeable cations released directly from wood ash into the soil suspension. The increase in suspension K was equivalent to 55% of the total K content of the wood ash. The net K content of the suspensions remained near the same level during the reaction period suggesting that soil solution levels of K would immediately increase upon landspreading of wood ash.
Pesticides in Iowa Precipitation
Authors: Nations B.K. , Hallberg G.R. 
Published: July 2010

AbstractRainfall was sampled for pesticides to assess their occurrence in precipitation and potential impacts on water resources. Three areas in Iowa were sampled; two localities were in rural settings, and a third in an urban area. Fourteen pesticides, including ten herbicides and four insecticides, were detected from October 1987 through September 1990. Atrazine, alachlor, cyanazine, and metolachlor were the most commonly detected, with one or more of these four herbicides found in almost every rainfall sample during the growing season. Concentrations of individual pesticides ranged from 0.1 µg L−1 to 40.0 µg L−1, with most detections under 1.0 µg L−1. Pesticide detections in rainfall began in April and ended in July or August, probably related to the timing of chemical application and greater volatilization rates during warmer weather. Samples from the urban site had detections of the same agricultural chemicals found at the rural sites, but in lesser quantities. In addition to the commonly detected herbicides, three of the four insecticides detected in rainfall were only found in urban samples. Two of these have urban as well as agricultural uses. Some variation of pesticide detections were seen at the three sampling localities, related to regional and local use patterns. Concentrations were greater at sampling sites near fields where pesticides are applied, suggesting that local volatilization and distance of transport affect the concentrations in rainfall. Pesticide concentrations were highest at the beginning of a rainfall event with concentrations becoming lower in samples taken later in the event.
Rapid Analysis of Climate Gases by Wide Bore Capillary Gas Chromatography
Authors: Sitaula Bishal K. , Luo Jiafa , Bakken Lars R. 
Published: July 2010

AbstractA gas chromatographic method that gives sensitive and rapid (3.3 min) measurement of the three greenhouse gases CO2, CH4, N2O is described. A wide bore capillary column operated at optimal conditions gave sufficient separation to allow a switch of the column flow between two detector systems (TCD and FID in series, and ECD) during the chromatogram; thus, all three gases could be analyzed with a single sample injection. Application of a peristaltic pump allowed gas samples to be transfered directly from gas sampling vials, through a drying agent [Mg (Cl04)2] and into the injection loop (0.5 mL) Back flushing of the injection system (pump and drying agent) with He between each injection ensured minimal carry over between samples (<0.6%). Experiences with storage of gas samples in vials with butyl rubber septa are described.
Determination of Alachlor, Atrazine, and Metribuzin in Soil by Resin Extraction
Authors: Basta N.T. , Olness Alan 
Published: July 2010

AbstractAn accurate and precise procedure for simultaneous resin extraction of alachlor (2‐chloro‐2′,6′‐diethyl‐N‐methoxymethylacetanilide), atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐1,3,5‐triazine), and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3(methylthio)‐1,2,4‐triazin‐5(4H)‐one] in soil extracts is described. The procedure consists of three steps: (i) equilibration of resin extractors (RE) with water extracts of soil, (ii) elution of pesticides from RE by using methanol, and (iii) determination and confirmation of pesticide by dual‐column gas chromatography with thermionic specific detection. Recovery of dissolved pesticides by anion‐exchange resin, cation‐exchange resin, and nonpolar resin was studied. Ion‐exchange resins generally adsorbed pesticides well, but showed poor desorption characteristics. The effect of solution pH and salt concentration on pesticide adsorption by a nonpolar resin was studied. Quantitative amounts of pesticide (>95%) were adsorbed from solution by a nonpolar resin over a wide range of solution pH (2.5–10.0) and dissolved salt (0–100 mM NaCl). Pesticide adsorbed by RE ranged from 80 to 90%, and methanol desorbed 80 to 85% of adsorbed pesticides. Overall pesticide recoveries by the RE procedure were very reproducible with an average recovery of 67.7 ± 2.0%. Results obtained by the RE procedure agreed closely with those obtained by solid‐phase extraction (SPE) with octadecyl (C18) bonded porous silica. Extraction time required by the RE procedure is a function of temperature and decreases from 5 d at 22 °C to 2 d at 75 °C. The RE procedure has the same degree of precision as C18‐SPE and is inexpensive.
Physical and Chemical Properties of Potential Topsoil Substitutes in Kentucky Oil Shale Mining Reclamation
Authors: Hower Judith M. , Barnhisel Richard I. , Hopkins T. C. 
Published: July 2010

AbstractBecause the soils that frequently overlie eastern U.S. oil shale outcrops and near‐surface deposits are relatively shallow, acidic, and infertile, use of topsoil substitutes and supplemental materials are anticipated to achieve satisfactory reclamation during surface mining. This study was conducted to determine the effects of weathering on selected overburden strata (the Borden and Bedford Shales) in terms of particle‐size distribution, moisture retention character, reactivity, and macronutrient availability. Shale samples were subjected to 40 freeze/thaw cycles in the laboratory to simulate field conditions. Laboratory analyses of “weathered” shales indicate these materials could be used as effective topsoil substitutes in mine reclamation. Shale weathering produced a material in the fine earth fraction that approached residual soils in ability to retain moisture and have low lime requirements. Suggested P amendment of weathered overburden was 75 to 150 kg P ha−1. Availability of K in weathered overburden exceeded levels in native soils and because these values were generally very high, K amendment of overburden materials would not be needed. To confirm these findings in terms of vegetative cover and growth response, the establishment of field test plots is necessary.
Carbon‐13 Nuclear Magnetic Resonance Spectra of Soil Water‐Soluble Organic Carbon
Authors: Novak J.M. , Bertsch P.M. , Mills G.L. 
Published: July 2010

AbstractWater‐soluble organic carbon (WSOC) was extracted from the surface horizon (0–15 cm) of a South Carolina floodplain soil (Pickney series‐sandy, silicious, thermic Cumulic Humaquepts) using either 1.2‐µm Whatman glass fiber type C (GF) or polycarbonate (PC) (<0.4 µm) filters. The trend in functional group C distribution for both WSOC fractions was O‐alkyl > aliphatic > aromatic > carboxylic acid > carbonyl structures. Overall, the 13C NMR spectra showed similar functional group C distributions for fractions obtained with both filters.
Herbicide Adsorption and Organic Carbon Contents on Adjacent Low‐Input Versus Conventional Farms
Authors: Mallawatantri A.P. , Mulla D.J. 
Published: July 2010

AbstractLittle quantitative information is available concerning the long‐term impact of alternative framing practices on herbicide adsorption and soil factors that control adsorption. The objective of this study was to evaluate the effects of long‐term conventional vs. long‐term, low‐input farming management practices on herbicide adsorption and soil properties that control adsorption at different landscape positions. Soil samples were collected at depths of 0 to 15 cm along a 350‐m boundary between adjacent long‐term conventional and low‐input farms near Spokane, WA. These samples were characterized for soil organic C (OC) and clay contents, soil pH, and linear adsorption partition coefficients (Kd) using the 14C radiolabeled herbicides metribuzin [4, amino‐6‐11,1‐dimethylethyl)‐3‐(methylthio)‐1,24‐triazine‐5(4,1,1)‐one], diuron, [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea], 2,4‐D [(2,4‐dichlorophenoxy)acetic acid], and triallate [S‐(2,3,3‐trichloroally) diisopropylthiocarbamate]. Carbon contents were significantly higher on the low‐input farm than the conventional farm at all slope positions, with values at the bottom slope position of 19.4 g kg−1 on the low‐input farm and 12.2 g kg−1 on the conventional farm. Carbon contents also decreased significantly at upper slope positions, with values at the top slope of 9.0 g kg−1 on the low‐input farm and 6.0 g kg−1 on the conventional farm. The Kd values for the four herbicides studied were significantly larger on the low‐input farm than the conventional farm at all slope positions. Significant decreases in adsorption occurred on both farms at top‐slope positions relative to bottom‐slope positions. From 80 to 95% of the increase in Kd values could be explained by increases in OC contents, but the best‐fitting regression line had a large negative intercept for metribuzin, 2,4‐D, and diuron. We conclude from this that although the regression model may be used to estimate Kd values from measured OC contents at moderate to high values of OC, the model has no physicochemical significance and the slope of the model does not equate to a value for Koc.
Water Quality Characteristics Associated with Southern Plains Grasslands
Authors: Smith S. J. , Sharpley A. N. , Berg W. A. , Naney J. W. , Coleman G. A. 
Published: July 2010

AbstractWater quality information regarding grasslands in the Southern Plains of Oklahoma and Texas is sparse. The objective of this study was to determine the extent to which the area's surface and groundwater quality is influenced by native and introduced grass management practices. Concentrations and amounts of sediment, N, and P in surface runoff water were determined for 14, 1‐ to 6‐ha watersheds in the Reddish Prairie and Rolling Red Plain land resource areas for periods of 3 to 13 yr. In general, surface water quality was influenced slightly during the study periods by dominant grass species, area grazing practices, or recommended fertilizer rates, but sediment losses were curtailed greatly by gully amelioration. Mean annual discharge ranged from 30 to 71 000 kg ha−1 for sediment, 0.1 to 11 kg ha−1 for total N, and 0.02 to 4 kg ha−1 for total P. Highest losses were from watersheds with established, active gullies. Annual soluble nutrient losses in surface runoff tended to be small, often <1 kg ha−1 N or P. Successful prediction of soluble P, particulate P, and particulate N in surface runoff was achieved using appropriate kinetic desorption and enrichment ratio procedures. Soluble N in surface runoff posed few water quality problems, but soluble and total P concentrations often exceeded proposed 0.01 and 0.02 mg L−1 respective critical limits for eutrophication, even on the more pristine watersheds. In the case of groundwaters, occasional, elevated NO3‐N (i.e., 18 mg L−1 maximum) concentrations were observed beneath certain N fertilized, introduced and native grasses on shallow water table (3–20 m depth), medium‐textured soils.