bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluxes of Carbon Dioxide, Nitrous Oxide, and Methane in Grass Sod and Winter Wheat‐Fallow Tillage Management
Authors: Kessavalou Anabayan , Mosier Arvin R. , Doran John W. , Drijber Rhae A. , Lyon Drew J. , Heinemeyer O. 
Published: July 2010

AbstractCropping and tillage management can increase atmospheric CO2, N2O, and CH4 concentrations, and contribute to global warming and destruction of the ozone layer. Fluxes of these gases in vented surface chambers, and water‐filled pore space (WFPS) and temperature of survace soil were measured weekly from a long‐term winter wheat (Triticum aestivum L.)‐fallow rotation system under chemical (no‐tillage) and mechanical tillage (noninversion subtillage at 7 to 10 cm or moldboard plowing to 15 cm) follow management and compared with those from “native” grass sod at Sidney, NE, from March 1993 to July 1995. Cropping, tillage, within‐field location, time of year, soil temperature, and WFPS influenced net greenhouse gas fluxes. Mean annual interrow CO2 emissions from wheat‐fallow ranged from 6.9 to 20.1 kg C ha−1 d−1 and generally increased with intensity and degree of tillage (no‐till least and plow greatest). Nitrous oxide flux averaged <1.2 g N ha−1 d−1 for sod and 1 to 2 g N ha−1 d−1 for wheat‐fallow. Tillage during fallow increased N2O flux by almost 100%. Nitrous oxide emissions were 1.5 to 3.7 times greater from crop row than interrow locations with greatest differences occurring during periods of highest N2O emission. Mean annual N2O flux over the 3 yr of study were 1.54 and 0.76 g N ha−1 d−1 for row and interrow locations. Methane uptake ranged from 5.9 to 9.9 g C ha−1 d−1 and was not influenced by row location. Seasonal CO2 and N2O flux, and CH4 uptake ranked as spring ≥ summer > autumn > winter. Winter periods accounted for 4 to 10% and 3 to 47% of the annual CO2 and N2O flux, respectively, and 12 to 21% of the annual CH4 uptake. Fluxes of CO2 and N2O, and CH4 uptake increased linearly with soil temperature. No‐till fallow exhibited the least threat to deterioration of atmospheric or soil quality as reflected by greater CH4 uptake, decreased N2O and CO2 emissions, and less loss of soil organic C than tilled soils. However, potential for increased C sequestration in this wheat‐fallow system is limited due to reduced C input from intermittent cropping.
Ammonia Volatilization from Tall Fescue Pastures Fertilized with Broiler Litter
Authors: Marshall S. B. , Wood C. W. , Braun L. C. , Cabrera M. L. , Mullen M. D. , Guertal E. A. 
Published: July 2010

AbstractAmmonia (NH3) volatilization is an important and often overlooked component of the N budget in many agricultural systems involving land application of animal wastes. We quantified the amount and rate of NH3 volatilization from broiler litter applied to established tall fescue pastures (Festuca arundinacea Schreb.). Study sites were located in the Coastal Plain (Alabama), Piedmont (Georgia), and Cumberland Plateau (Tennessee) Major Land Resource Areas (MLRA) of the southeast USA. Litter was applied to supply 70 kg of available N ha−1 based on equations developed by the U.S. Department of Agriculture (USDA) and the U.S. Environmental Protection Agency (USEPA). Measurements of NH3‐N volatilization were taken using a micrometeorological, field‐scale technique for 14 d immediately following litter application during the spring of 1995 and 1996. Ammonia flux for the study period ranged from 3.7 to 10.6 kg N ha−1 in 1995, and from 3.5 to 8.0 kg N ha−1 in 1996. A sharp increase in volatilization rate occurred 1 to 3 d after litter application at all three sites in both years. However, volatilization rates rapidly decreased to normal levels within 10 d. Volatilization rates peaked at 2.8 kg NH3‐N ha−1 d−1 in 1995 and 2.2 kg NH3‐N ha−1 d−1 in 1996. Overall, N losses due to NH3 volatilization were less than expected based on previous studies. These data suggest that for these conditions, NH3 volatilization was a relatively minor component of the N cycle and was not a major pathway for N loss.
Accumulation Dynamics of Triclopyr Ester in Aquatic Leaf Packs and Effects on Detritivorous Insects
Authors: Kreutzweiser David P. , Thompson Dean G. , Staznik Bozena , Shepherd Janelle A. 
Published: July 2010

AbstractPrevious field studies have demonstrated that residues of the herbicide, triclopyr butoxyethyl ester (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid, butoxyethyl ester) (TBEE), can accumulate in submerged leaf material of aquatic systems at concentrations up to 20 times the maximum aqueous concentrations. Accumulated TBEE residues may pose a risk of adverse effects to detritivorous invertebrates inhabiting and using natural leaf packs. We examined the dynamics of TBEE accumulation and persistence in leaf materials of laboratory and outdoor aquatic systems, and determined the ecological significance of this in terms of effects on detritivorous insects and organic matter processing. Accumulations of TBEE in leaf packs of semi‐static laboratory microcosms were up to 80 times aqueous concentrations, and residues persisted for 4 to 5 d. Leaf material of flow‐through laboratory microcosms accumulated TBEE at much higher rates (up to 1000 times aqueous concentrations), but residues were cleared by 48 to 72 h. Accumulation and persistence in flow‐through units were dependent on water depth, velocity, and exposure duration. Accumulated TBEE residues were less in outdoor stream channels than in laboratory flow‐through units, probably because of losses through sorption to natural benthic material in the stream channels. Despite accumulations of TBEE in leaf packs at up to 90 mg kg−1 in systems treated at or near expected environmental concentrations, there was no significant mortality of detritivorous insects and no significant reductions in leaf consumption. Significant mortality and reduced feeding occurred only in systems treated at concentrations well above (up to 10 times) expected environmental concentrations.
Long‐Term Soil Redistribution in a Small French Watershed as Estimated from Cesium‐137 Data
Authors: Bernard Claude , Mabit Lionel , Wicherek Stanislas , Laverdière Marc R. 
Published: July 2010

AbstractChanges initiated in the 1970s in the agricultural landscape of the north European plains have resulted in increased water erosion. The spatial redistribution of 137Cs was used to assess the magnitude of long‐term soil movements in a 180 ha watershed located in northern France. The 137Cs base level was estimated at 2000 ± 200 Bq m−2. The point data suggest annual soil movements ranging from a loss of 18 Mg ha−1 to a deposition of 19 Mg ha−1. After spatializing these data, it is concluded that 41% of the watershed area can be considered as stable. Some 45% of the watershed area suffered a net soil loss, with an average rate of 6 Mg ha−1 yr−1. Net deposition occurred over 14% of the area, with an average annual rate of 7 Mg ha−1. From these values, it was estimated that a net output of 1.9 Mg ha−1 yr−1 of eroded material would have left the watershed. This represents a sediment delivery ratio of 59%. These results are consistent with those of other European researchers under comparable environments. They also stress the point that redeposition is an important part of the global erosion process. Finally, these results highlight some of the advantages of the 137Cs technique, which makes possible the development of long‐term sediment budgets at the watershed scale.
Natural‐Gradient Transport of Bromide, Atrazine, and Alachlor in an Organic Carbon‐Rich Aquifer
Authors: Springer A. E. , Bair E. S. 
Published: July 2010

AbstractIn situ values of retardation factors and dispersivity were determined from a field tracer study using bromide, atrazine (2‐chloro‐4‐ethlamino‐6‐isopropylamineo‐s‐triazine), and alachlor (2‐chloro‐2′‐6′‐diethyl‐N‐(methoxymethyl)‐acetanilide). The tracers were injected at the water table in an unconfined aquifer to evaluate how these pesticides are attenuated within the groundwater flow system in a typical alluvial valley setting in the Midwest where corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] are the dominant crops and atrazine and alachlor are the most commonly used pesticides. Water samples were collected for 49 d after tracer injection from 63 wells to establish the direction and magnitude of tracer movement. Following injection, no degradation products of atrazine were detected in any of the monitoring wells. Aquifer hydraulic properties were measured in the field prior to the test. Sorption on organic carbon (0.0009–0.0016 Mg/Mg) in the aquifer caused the transport of atrazine and alachlor to be retarded relative to bromide. At the scale of the field test, retardation factors of 6.1 and 7.1 were estimated for atrazine and alachlor, respectively, based on a one‐dimensional, nonlinear least squares inversion analysis. These retardation factors are two to three times larger than retardation factors measured in laboratory batch tests using the same aquifer materials, are larger than other values reported in the literature, and are due to the relatively large fraction of organic C found in the aquifer. Dispersivity was approximately 9 cm at a distance of 1 to 2 m from the injection well and approximately 140 cm at a distance of 5 m from the injection well.
Remediating RDX‐Contaminated Water and Soil Using Zero‐Valent Iron
Authors: Singh J. , Comfort S. D. , Shea P. J. 
Published: July 2010

AbstractSoil and water contaminated with RDX (hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) pose a serious threat to the environment and human health. Our objective was to determine the potential for using zero‐valent iron (Fe0) to remediate RDX‐contaminated water and soil. Mixing an aqueous solution of 32 mg RDX L−1 (spiked with 14C‐labeled RDX) with 10 g Fe0 L−1 resulted in complete RDX destruction within 72 h. Nitroso derivatives of RDX accounted for approximately 26% of the RDX transformed during the first 24 h; these intermediates disappeared within 96 h and the remaining 14C products were water soluble and not strongly sorbed by iron surfaces. When RDX‐contaminated soil (30 mg RDX kg−1 spiked with 14C‐RDX) was treated with a single amendment of Fe0 (20 g kg−1 soil) in a static soil microcosm, more than 60% of the initial 14C‐RDX was recovered as 14CO2 after 112 d. Treating surface and subsurface soils containing 3600 mg RDX kg−1 with 50 g Fe0 kg−1 at a constant soil water content (0.35–0.40 kg H2O kg−1 soil) resulted in a 52% reduction in extractable RDX following 12 mo of static incubation. A second Fe0 addition at 12 mo further reduced the initial extractable RDX by 71% after 15 mo. These results support the use of zero‐valent iron for in situ remediation of RDX‐contaminated soil.
Nitrogen Leaching from Unlined Cull‐Onion Landfills
Authors: Hutchings J. J. , Hammel J. E. , Osiensky J. L. 
Published: July 2010

AbstractDisposal of cull onions (Allium cepa L.) in unlined landfills in the Treasure Valley region of eastern Oregon and southwestern Idaho is a historic management practice that has been identified as potentially causing NO3‐N contamination of regional groundwater. To investigate NO3‐N generation and transport during a 6‐yr period, monitoring wells were placed in the cull onion waste inside two landfills. The soil below each landfill was instrumented with soil‐solution samplers and matric‐potential sensors. Four to 6 Mg of organic N were loaded into each landfill in the form of onion waste. Little leaching of NO3‐N was observed during the study. With the exception of a NO3‐N pulse during loading, solution NO3‐N concentrations within and beneath both landfills remained <1 mg L−1. Concurrently, NH4‐N increased to 500 mg L−1 at 0.5 m and to 7 mg L−1 at 3 m below the landfill bases. Build‐up of NH4‐N and lack of NO3‐N in the landfills are hypothesized to result from nitrification inhibition in an anaerobic environment. Hydraulic heads showed that saturated waste resided over unsaturated soil. Formation of a hydraulically restrictive layer at the interface between the landfill contents and the underlying soil probably caused these conditions. Saturated cull‐onion landfills do not appear to be a source of NO3‐N contamination. Potential groundwater contamination from nitrification upon drying of landfill contents can be mitigated by removing and land‐applying residual waste after sufficient degradation.
Boron, Zinc, Iron, and Manganese Content in Four Grassland Species
Authors: Adarve M. J. , Hernández A. J. , Gil A. , Pastor J. 
Published: July 2010

AbstractA pot experiment was carried out to test the response of the B, Zn, Fe, and Mn concentration in four wild herbaceous species exposed to three landfill leachate treatments of increasing concentration of contaminants. The species tested were clustered clover (Trifolium glomeratum L.), cotton clover (T. tomentosum L.), wall barley (Hordeum murinum L.), and soft brome (Bromus hordaceus L.). The legume species accumulated more Fe and B than the grasses. The least contaminated leachate (leachate A) significantly increased the Fe and Mn content in T. glomeratum. Leachate B significantly increased the Zn content in both clover species and Fe content in T. glomeratum and H. murinum, while it significantly decreased the B content in T. glomeratum. The most contaminated leachate (leachate C) significantly increased the Zn content in T. glomeratum, while it significantly decreased the B and Fe content. In the four species the content of B, Fe, and Mn in the plants under the leachate treatments was in a normal values range, while in T. glomeratum and H. murinum the Zn content had in some cases a toxic level (>100 mg L−1). The dry weight of the four species tested diminished significantly under the most contaminated leachate. The ANOVA confirmed a major significant influence of the “species factor” on the response of the plant to leachate supply, but the treatment factor also had significant F‐values in some cases. The species tested have a potential revegetation value for some areas degraded by landfill leachates.
Comparison of Four USEPA Digestion Methods for Trace Metal Analysis Using Certified and Florida Soils
Authors: Chen Ming , Ma Lena Q. 
Published: July 2010

AbstractIt is critical to compare existing sample digestion methods for evaluating soil contamination and remediation. USEPA Methods 3050, 3051, 3051a, and 3052 were used to digest standard reference materials and representative Florida surface soils. Fifteen trace metals (Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, and Zn), and six macro elements (Al, Ca, Fe, K, Mg, and P) were analyzed. Precise analysis was achieved for all elements except for Cd, Mo, Se, and Sb in NIST SRMs 2704 and 2709 by USEPA Methods 3050 and 3051, and for all elements except for As, Mo, Sb, and Se in NIST SRM 2711 by USEPA Method 3052. No significant differences were observed for the three NIST SRMs between the microwave‐assisted USEPA Methods 3051 and 3051a and the conventional USEPA Method 3050 except for Hg, Sb, and Se. USEPA Method 3051a provided comparable values for NIST SRMs certified using USEPA Method 3050. However, for method correlation coefficients and elemental recoveries in 40 Florida surface soils, USEPA Method 3051a was an overall better alternative for Method 3050 than was Method 3051. Among the four digestion methods, the microwave‐assisted USEPA Method 3052 achieved satisfactory recoveries for all elements except As and Mg using NIST SRM 2711. This total‐total digestion method provided greater recoveries for 12 elements Ag, Be, Cr, Fe, K, Mn, Mo, Ni, Pb, Sb, Se, and Zn, but lower recoveries for Mg in Florida soils than did the total‐recoverable digestion methods (3050, 3051, and 3051a).
Formulation and Adjuvant Effects on Leaching of Atrazine and Metolachlor
Authors: Hall J. K. , Jones G. A. , Hickman M. V. , Amistadi M. K. , Bogus E. R. , Mumma R. O. , Hartwig N. L. , Hoffman L. D. 
Published: July 2010

AbstractAtrazine (6‐chloro‐N‐ethyl‐N′‐(methyethyl)‐1,3,5‐triazine‐2,4‐diamine) and metolachlor (2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide) levels in pan lysimeter leachates, collected 1.2 m deep in a Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf), were used to evaluate leaching of these chemicals applied in combination (1.7 + 1.7; 3.4 + 3.4 kg a.i. ha−1) as a commercial formulation (CF) or adjuvant (polyacrylate polymer)‐amended (AA)‐CF and as a microencapsulated (ME) or starch‐encapsulated (SE) formulation in conventional tillage (CT) and no‐tillage planted corn (Zea mays L.). Atrazine leached more under NT than CT conditions. Areal losses of atrazine in 1992 from NT at the low rate were 4, 66, and 277 µg m−2 for the treatment sequence (CF, SE, and AA‐CF); at the high rate, losses were 887, 488, and 334 µg m−2. These amounts represented losses of <0.01 to 0.16% and 0.26 to 0.10%, respectively, of applied rates. In 1993, areal losses for the treatment succession (lesser rate) were 888, 253, and 497 µg m−2 of atrazine (0.52, 0.15, and 0.29%); these treatments (greater rate) yielded 5440, 1220, and 1600 µg m−2 of applied chemical (1.60, 0.36, and 0.47%). Application of ME (polyurea polymer) and AA‐metolachlor reduced mobility of this chemical at both rates in 1993, but their effect was especially exemplified at the greater rate where a loss of 2.29% (CF) was reduced to 0.83% (ME) and 0.54% (AA). Where herbicide leaching was reduced, greater concentrations, particularly atrazine, were detected in the surface 15 cm of soil in late‐season and in leachates, 6 to 12 mo following application.
Impacts of Historical Changes in Land Use and Dairy Herds on Water Quality in the Catskills Mountains
Authors: Scott C. A. , Walter M. F. , Brooks E. S. , Boll J. , Hes M. B. , Merrill M. D. 
Published: July 2010

AbstractSurface water eutrophication has been linked to nonpoint sources of agricultural nutrients. Based on 1938 and 1968 aerial photos and 1993 Landsat imagery of a 31.7 km2 watershed, corn (Zea mays L.)/hay rotation, pasture, forest, and impervious/water land uses were digitized in a raster GIS. Monthly runoff volumes resulting from each year's land use were predicted using a variable source area hydrologic model. Historical data on dairy animal populations and the spatial distribution of current soil test phosphorus (STP) levels were used to derive manure loading intensities. Event‐mean SP concentration in runoff as a function of manure application intensity and soil test P was derived from field data and published sources. The maximum predicted event‐mean SP concentration in runoff was 15.8 mg L−1. Watershed average potential SP loading to perennial streams remained essentially constant at 0.14 kg ha−1 yr−1 over the period 1938 to 1993. Herd size and total manure load dropped significantly over the period 1938 to 1993; however, the P content in manure and confinement of animals increased, counteracting the hypothesized trend that SP loading would drop. The analyses indicate that, for 1993, <6% of the agricultural land accounted for 50% of the agricultural SP load, suggesting that with improved manure handling practices over a relatively small area, it may be feasible to reduce SP loads to streams.
Revegetation on a Coal Fine Ash Disposal Site in South Africa
Authors: Van Rensburg L. , De Sousa Correia R. I. , Booysen J. , Ginster M. 
Published: July 2010

AbstractEight medium amendments were conducted on top of a fine ash coal dump (i) to evaluate a few cost‐effective treatments that could determine the minimum fertility status required for the local ash to support the establishment of a viable vegetation cover, and (ii) to select suitable grass species that would establish on the ash and could serve as a foundation for long‐term rehabilitation. Degree and success of grass establishment per medium amelioration treatment is expressed in terms of total biomass, percentage basal cover, and in terms of a condition assessment model. Both the chemical and physical nature of the ash medium before and after amendment was characterized, as were the concentrations of some essential and potentially toxic elements in leaf samples. In terms of medium amelioration 5000 kg ha−1 compost, or 500 kg ha−1 kraal manure or 480 kg 2:3:2 ha−1 proved to be most effective. The grass species that occurred with the highest frequency, irrespective of treatment, were the perennials bermudagrass [Cynodon dactylon (L.) Pers. var. dactylon], weeping lovegrass [Eragrostis curvula (Schrader) Nees], and the annual teff [Eragrostis tef (Zuccagni) Trotter]. Of the potentially toxic extractable metals monitored in the leaves of vegetation on the dump, only Se accumulated to an average level of 4.4 mg kg−1 that could be toxic to livestock.
The Effect of Acidification and Chelating Agents on the Solubilization of Uranium from Contaminated Soil
Authors: Ebbs Stephen D. , Norvell Wendell A. , Kochian Leon V. 
Published: July 2010

AbstractThe role of acidification and chelating agents in the solubilization of uranium (U) from contaminated soil was examined in a series of experiments. Soil acidification and the addition of chelating agents were the two methods compared initially. The results indicated that the addition of citric acid solubilized more U than acidification or the other amendments tested. This increase in U solubility was, however, transitory. A subsequent experiment indicated that citrate concentration had a more dramatic effect on U solubility than did acidification. The greatest soluble U concentration during this experiment (775 mg kg−1 soil, or ∼85% of the total U) was observed after 24 h in the presence of 20 millimoles citrate kg−1 soil at pH 5. The persistence of U solubility over the 96‐h experimental period was primarily a function of pH and citrate degradation. In a separate experiment, in which citric acid rather than citrate was added to contaminated soil, the soluble U concentrations observed were generally lower than those observed in the presence of citrate. Citric acid decreased soil pH to values ≤3.6, and solubilized higher concentrations of Al and Fe than observed in the presence of citrate. Since the maximum solubilization of U was observed at pH 5, the implication of these results is that a combined approach, using both soil acidification and citric acid addition, may be necessary to maximize the phytoextraction of U from soils with a pH > 6.0.
Particle‐Facilitated Transport of Prochloraz in Undisturbed Sandy Loam Soil Columns
Authors: de Jonge H. , Jacobsen O. H. , de Jonge L. W. , Moldrup P. 
Published: July 2010

AbstractThe mobility of strongly sorbing pesticides in soils may be higher than formerly assumed, due to facilitated transport along with mobilized colloids. Our objective was to verify whether facilitated transport enhances the vertical movement of prochloraz (N‐propyl‐N‐[2‐(2,4,6‐trichlorophenoxy)ethyl] imidazole‐1‐carboxamide). Experiments were carried out using 20 cm diam. by 20 cm long undisturbed soil columns taken from the topsoil (sandy loam, Typic Hapludalf) from a field under barley/grass (Hordeum vulgare L/Lolium perenne L.) cultivation near Rogen, Denmark. Prochloraz was applied to the surface as a pulse in solution. The irrigation intensity was 10 mm h−1, and the lower boundary of the columns was at atmospheric pressure. Three treatments each with four replicates were performed to study the effect of ionic strength and pH on pesticide and particle transport. Leaching of particles and pesticide was promoted by decreasing the ionic strength of the irrigation solution, and increasing pH by ammonia application. This is in line with the theory of electrostatic interactions. Preferential flow and particle transport were the two most important factors determining the amount of pesticide leached. A large variability in amount leached was observed among the replicates (standard deviations of 38–141%) mainly due to differences in water transport in the columns. Particle‐facilitated transport was significant, but did not dominate prochloraz transport. Depending on the pH and ionic strength of the applied solution, 2.5 to 13.1% of the leached pesticide was sorbed to particles with diameter d > 0.24 µm, and 3 to 9% to particles with 0.02 < d < 0.24 µm.