bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural Mycorrhizal Colonization of Pines on Reclaimed Surface Mines in Virginia
Authors: Schoenholtz Stephen H. , Burger James A. , Torbert John L. 
Published: July 2010

AbstractThe effects of spoil type, slow‐release fertilization, and weed control using glyphosate on the degree of ectomycorrhizal colonization of container‐grown white (Pinus strobus L.), loblolly (P. taeda L.), and Virginia (P. virginiana Mill.) pines were studied on two strip‐mined sites (sandstone vs. siltstone overburden material) in southwestern Virginia. Although some seedlings were successfully colonized at both sites, the number of seedlings colonized and the proportion of short‐root colonization per seedling were consistently higher on the sandstone spoil. On both sites, loblolly and Virginia pines had more ectomycorrhizal formation than white pine. Foliar P levels of all three species on the sandstone spoil and of loblolly pine on the siltstone spoil were significantly correlated with ectomycorrhizal development. The degree of ectomycorrhizal formation for any of the species on either spoil was not decreased by slow‐release fertilization or glyphosate applications. These results indicate that natural mycorrhizal colonization is compatible with these cultural treatments, and that colonization from indigenous fungal species may be adequate, eliminating the need for artificial inoculation.
Microbial Mobilization of Cadmium in Soil Under Aerobic and Anaerobic Conditions
Authors: Chanmugathas Pushparany , Bollag Jean‐Marc 
Published: July 2010

AbstractThe role of microorganisms in Cd mobilization from soils was investigated. Soils treated with Cd and washed to remove readily soluble Cd were suspended in a nutrient medium (at a ratio of 1:20 wt/v) and incubated (aerobically or anaerobically) for a period of 160 d. While no Cd was released from gamma‐irradiated sterile soils under aerobic or anaerobic conditions, a significant amount of “strongly bound” or “fixed” Cd was mobilized from nonsterile samples of all softs tested. The rate and extent of microbial Cd mobilization was dependent on the soil type, aeration, and moisture content. Among the four soils tested, Morrison sandy loam and Morrison loam soils (Ultic Hapludalfs) showed aerobically and anaerobically a greater degree and a faster rate of microbial Cd mobilization compared to Hagerstown silt loam soils (Typic Hapludaifs). In all soils but the Morrison sandy loam soil, the amount of Cd released was considerably greater under anaerobic than aerobic conditions. Although soil moisture content did not have a distinct effect in anaerobic experiments, under aerobic conditions air‐dried field soils exhibited a significantly greater rate and extent of microbial Cd mobilization than did fresh soils that had been kept moist at 5 °C. Cadmium release was much more rapid during anaerobic incubation, but upon prolonged incubation (up to 3 weeks), a continued removal of Cd from the aqueous phase occurred in anaerobic, but not the aerobic samples. In many instances, the pH of the soil suspensions decreased to an acidic level (near pH 5.5) with a concurrent release of Cd. Based on our results, mobilization of strongly bound or fixed Cd is a microbially mediated process and this is affected by soil environmental factors such as soil type, aeration, and moisture content.
Short‐term Transformations of Copper in Copper‐amended Soils
Authors: Miller W. P. , Martens D. C. , Zelazny L. W. 
Published: July 2010

AbstractCopper was added to three soils in the laboratory at a rate of 48 mg Cu kg−1 in the form of either CuSO4 or a swine (Sus scrofa domesticus) manure obtained from swine fed a high‐Cu ration (equivalent to 100 Mg manure ha−1 containing 1060 mg Cu kg−1). In order to assess the potential transformations of the added Cu among various chemical forms in the soils, a sequential extraction methodology was used to determine types of soil‐Cu associations in samples taken 1, 4, 12, and 29 d after Cu additions to moist soils. Copper added as high‐Cu manure substantially increased water‐extractable Cu in all soils through the entire incubation period, while CuSO4 additions resulted in higher exchangeable Cu levels through days 4 to 12. Most of the Cu added in both forms was recovered in “specifically adsorbed” forms, with 20 to 25 mg CuSO4‐Cu kg−1 being Pb‐extractable and 15 to 20 mg manure‐Cu kg−1 being acetic acid‐extractable throughout the incubation period. Significant amounts of Cu were also associated with soil organic matter (K4P2O7‐extractable), more so when the Cu was added as high‐Cu manure (10–15 mg Cu kg−1) than as CuSO4 (5 mg kg−1). Some additional added Cu was associated with Mn oxides and noncrystalline Fe oxides after 12 d of incubation, particularly in the two soils containing higher amounts of these oxides. These results suggest increases in short‐term availability and mobility of Cu in these soils, particularly with high‐Cu manure amendment, although longer‐term reversion processes may reduce bioavailability over time.
Tilted‐bed Simulation of Erosion and Chemical Runoff from Agricultural Fields: I. Runoff of Sediment and Sediment‐associated Copper and Zinc
Authors: Wauchope R. Don 
Published: July 2010

AbstractPesticide loss from agricultural fields by runoff was simulated using a rainfall simulator over 2.2‐ by 1.2‐m fiberglass “tilted bed” soil trays. Intense rainfall events were applied to eight trays containing a loam soil at 1.3 ± 0.4% slope. To simulate soil‐surface‐applied pesticides thai are lost in the sediment phase of runoff, the soil surfaces of six of the trays (two were used as controls) were sprayed with aqueous solutions of Cu and Zn salts to give “application rates” of 1 kg elemental Cu and Zn/ha. The rainfall simulator applied 30 mm of rain to the trays in 5 min with a CV of 10%, and an average of 7.6 mm of runoff was obtained with a CV of 14%. The trays that received salt applications showed significantly lower erosion rates (629 ± 160 kg/ha) than those that did not receive salts (1200 ± 100 kg/ha), even though the total salt applied was only 11 kg/ha. All measurable Cu and Zn was found in the sediment phase of the runoff, and enrichment of the metals in the sediment was a function of runoff flow rate. The estimated adsorption constants (Kd) for Cu and Zn in this soil were 186 and 20, respectively, but this difference did not effect runoff losses; the total loads of Cu and Zn from individual trays, after correction for background Cu and Zn, were essentially identical and highly correlated with soil loss. The total losses of the tracers ranged from 3 to 7% of the amounts applied, in good agreement with field studies of losses of pesticides strongly bound to soil. These results suggest that this system may provide an inexpensive alternative to field testing for pesticide mobility in runoff, and provide insights into the physical process by which pesticides are entrained into runoff.
Simultaneous Determination of Nitrification and Nitrate Reduction in Sediment‐Water Columns by Nitrate‐15 Dilution
Authors: DeLaune R. D. , Smith C. J. 
Published: July 2010

AbstractThe magnitude of N loss from nitrification‐denitrification reactions in sediment‐water columns of a freshwater lake of Louisiana Gulf Coast drainage basin receiving elevated N loading from agricultural runoff was determining using 15NO3 dilution. Isotope dilution using added labeled NO3 allowed for the simultaneous determination of nitrification and NO3 reduction in the sediment‐water column. The contribution of internal NH4 pools in bottom sediment to NO3 content in water column through diffusion and nitrification was measured. Nitrate reduction averaged 134 µmol m−2 h−1 over a 50‐d incubation period in the sediment‐water columns. Nitrification averaged 90 µmol m−2 h−1, approximately 70% of the denitrification rate. Nitrification and ammonium assimilation were also determined in lake water using 15N‐labeled NH4 as a tracer. The nitrification rate determined in the water (0.9–1.4 mmol N m−3 d−1) was less than the rates measured in the sediment‐water columns (1.4–3.3 mmol N m−3 d−1) using 15NO3 dilution. The results presented and isotope dilution technique used are applicable for use in understanding the fate of N in sediment‐water systems of other aquatic environments.
Variability in Sorption Coefficients of Metolachlor on a Captina Silt Loam
Authors: Wood L. S. , Scott H. D. , Marx D. B. , Lavy T. L. 
Published: July 2010

AbstractSpatial variability of soil properties is important in determining pesticide behavior in soils. A study was conducted on a 4‐ha field to measure the spatial variability in sorption coefficients (K) for the herbicide metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl)acetamide] and to correlate these K values to other soil properties. The soils in this field were Captina and Johnsburg (Typic Fragiudults). The rectangular field was sampled on a grid with 135 nodes. At each node, samples of the Ap, Bt, and Btx horizons were taken for determinations of water content at 10 and 1500 kPa, pH, particle size analysis, sorption coefficients (K), and organic matter content. Means, standard deviations, minimum values, maximum values, and coefficients of variation (CV) were determined on all properties. In addition, multiple linear regression analyses were performed to determine the maximum correlation between K and the soil properties. Soil organic matter content was the soil property most highly correlated with the adsorption of metolachlor in the surface soils (Ap). Adsorption was also significantly correlated with clay content, water content at 1500 kPa, and pH. Semivariograms were constructed for each horizon for the organic matter content and K. Semivariograms for organic matter indicated a range of spatial dependency of 110 m in the Ap and no spatial structure for the Bt and Btx horizons. The range for K was 110 m in the Ap and 42 m in the Bt with no spatial structure evident in the Btx horizon. The data for K and organic matter were normalized by dividing each semivariance by the mean squared for each parameter, which resulted in similar semivariograms in the Ap horizon. Contour plots of kriged values for normalized organic matter and normalized K in the Ap horizon were also similar.
Microbial Degradation of 1,2‐Dibromoethane in Shallow Aquifer Materials
Authors: Pignatello Joseph J. 
Published: July 2010

AbstractThe use of 1,2‐dibromoethane (ethylene dibromide, EDB) as a soil fumigant in agriculture has resulted in groundwater contamination. The objective of this study was to determine the importance of microbial degradation to natural decontamination of EDB in aquifer materials. Shallow aquifer materials were obtained from two sites in Connecticut that are contaminated with EDB. Experiments were conducted in batch microcosms of core soil material and groundwater (no additional nutrients) at temperatures and initial EDB concentrations representative of the sites (9°C, 0.5–5 µg kg−1). Ethylene dibromide was degraded aerobically in all samples except autoclaved controls; products of [14C]‐EDB degradation included varying amounts of 14CO2, solid‐bound 14C (microbial biomass), and a nonvolatile water soluble fraction. At one of the sites, rates were faster in samples obtained from within the contaminant plume, suggesting adaptation of the microbial community to the presence of the chemical. Degradation was slowed at low‐oxygen (ca. 0.1 mg O2 L−1) compared to air‐saturated (ca. 11 mg O2 L−1) conditions. The compound was also degraded in the absence of oxygen but the products were not investigated. First‐order half‐lives under all conditions tested ranged from 35 to 350 d. The implications of these results to natural loss of EDB at one of the sites are discussed.
Relative Efficiency of Factorial Designs for Estimating Response Surfaces with Reference to Gaseous Pollutant Mixtures
Authors: Allen O. B. , Marie B. A. , Ormrod D. P. 
Published: July 2010

AbstractThe evaluation of the effects of air pollutant mixtures on plant growth is very demanding of experimental resources since each replicate of each pollutant treatment requires a separate chamber. Consequently the choice of an efficient experimental design is particularly important. In 1954 Box was the first researcher to recognize that when all factors are quantitative, complete factorial designs are often inefficient. He proposed using a class of incomplete factorial designs termed response surface designs. This paper presents the statistical methodology for comparing experimental designs and illustrates this methodology by comparing five commonly used two factor designs—three response surface designs and two complete factorial designs. The response surface designs were the most efficient. However, failure to replicate the center point as recommended will dramatically reduce efficiency of the design near the center. Placement of treatments outside the region of interest can increase precision within the region of interest, particularly near the boundary. The methodology that is presented may be used for comparing designs with any number of factors.
Accumulation of Selenium in Crops Grown on Sludge‐treated Soil
Authors: Logan T. J. , Chang A. C. , Page A. L. , Ganje T. J. 
Published: July 2010

AbstractUptake by barley (Hordeum vulgare L. var. Briggs), Swiss chard (Beta vulgaris L. var. Fordhook), and radish (Raphanus sativas L. var. Cherry Belle) of Se from composted Los Angeles County sewage sludge applied to land was studied in a long‐term field study. Sludge was applied at 0, 22.5, 45, 90, and 180 Mg/ha per year for 8 to 10 yr and the data reported here are for the last year of the study. Total surface (0–15 cm) soil Se increased with the highest rate of sludge addition from <0.1 mg/kg in the control soil to 1.2 mg/kg. Only 13 to 25% of the sludge‐applied Se could be accounted for in the 0‐ to 15‐cm depth of incorporation and there was no measurable Se (<0.1 mg/kg) in the subsoil to 150 cm. There was little or no measurable uptake of Se by barley leaf and grain at the level of detection (0.05 mg/kg) of this study, and there were also no significant increases in chard or radish Se concentrations with sludge addition. Selenium concentrations in chard (0.05–0.11 mg/kg) were severalfold lower than those in radish (0.17–0.26 mg/kg).
Relative Effectiveness of Sewage Sludge as a Nitrogen Fertilizer for Tall Fescue
Authors: Kiemnec G. L. , Jackson T. L. , Hemphill D. D. , Volk V. V. 
Published: July 2010

AbstractSewage sludge application rates on grasses are mainly determined by N availability and concentration of toxic metals in sludge. The exact availability of N in sludge is difficult to predict. A 3‐yr study was conducted to determine which sludge rates would give yields of tall rescue (Festuca arundinacea Shreb. ‘Alta’) comparable to yields obtained from inorganic N application. Sludge and NH4NO3 were surface applied at annual rates of 0, 110, 220, 440, and 880 (sludge only) kg N/ha. Dry matter yield of tall rescue from sludge‐treated soils was 36, 56, and 50% of that on NH4NO3‐treated soils for 1976, 1977, and 1978, respectively. Sludge was 27, 41, and 44% as effective as NH4NO3 as a source of available N in 1976, 1977, and 1978, respectively. Ammonium‐N in the sewage sludge apparently provided most of the available N for fescue growth. Concentrations of Zn, Cd, and Cu were higher and Mn lower in tall fescue grown on sludge‐treated soil with NH4NO3 and usually increased toward the end of the growing season. However, plant concentrations of these heavy metals never reached toxic levels at any time. Sewage sludge was an effective and safe nutrient source for tall fescue.
Phosphorus Renovation of Wastewater by Overland Flow Land Application
Authors: Payer Frank S. , Weil Ray R. 
Published: July 2010

AbstractAn operating overland flow wastewater system was studied. Three treatments were imposed on the Reed canarygrass (Phalaris arundinacea L.) cover: cut four times per year and harvest residue (treatment 1); cut four times per year and leave residue (treatment 2); and cut one time per year and leave residue (treatment 3). Effluent was sampled at 6, 12, 18, and 37 m from the point of application as well as from final collection weirs and spray nozzles. Samples were collected at the beginning and the end of four continuous application periods, which were followed by rest periods of 4 to 6 weeks. Hydraulic loadings were 14 to 20 cm week−1 (0.035 m3 m−1 h−1) of effluent containing 1.6 mg P L−1. The removal rates for total P for three periods ranged from 62 to 72%, but there was no net total P removal during the first period (July). The removal rate for dissolved P was significantly greater at the end than at the beginning of the application period in three out of four cases. Following the season's final cutting in the fall, treatment 1 was significantly more efficient than treatment 3 for the removal of mass ortho‐P. Plant uptake accounted for 45% of the total P annually removed by the system. It was suggested that more intensive cutting and harvesting might further improve P removal rates. On several occasions, dissolved P concentration was greater on the 6‐m flow distance than in the influent as applied. The dispersed condition of the surface soil/thatch apparently affected P removal processes. In general, the extended periods of continuous application did not appear to reduce the system's capacity for P removal and offered some management flexibility.
Tebuthiuron Distribution in Soil following Application of Pellets
Authors: Whisenant Steven G. , Clary Warren P. 
Published: July 2010

AbstractPersistence, activity, and distribution of tebuthiuron {N‐[5‐(1,1 dimethylethyl)‐1,3,4‐thiadiazol‐2‐yl]‐N,N′‐dimethylurea} in two soils were studied following application of 40% active ingredients (a.i.) extruded pellets. Tebuthiuron dissipation from the surface 3 cm and within 2 cm of the point of pellet placement was best explained by the nonlinear regression equation: Y = bXa, where Y is the tebuthiuron concentration in milligrams per kilogram, b is 7.05 × 106, X is time (d) after pellet placement, and a is −2.272 (r2 = 0.97). Applications of 40% tebuthiuron pellets at 0.6 or 1.1 kg ha−1 left a detectable residue on 9 to 21 and 17 to 38% of the treated areas, respectively. The lower percentages were on a loam soil with 47 g kg−1 soil organic carbon (OC) content and the higher percentages were on loam soils with 17 and 18 g kg−1 OC. Crested wheatgrass [Agropyron cristatum (L.) Gaertn.] seedling growth was reduced 50% (GR50) by tebuthiuron concentrations of 0.04 to 0.20 mg kg−1, depending on soil OC content. Two years after application of 0.6 kg ha−1, 40% tebuthiuron pellets to a big sagebrush (Artemisia tridentata Nutt.) community, with a loam soil that had a 30% shrub cover (17 g kg−1 OC in interspaces and 48 g kg−1 OC under former shrub canopies), <20% of the surface soil contained the crested wheatgrass GR50.
Growth of Rillscale on Bentonite Mine Spoil as Influenced by Amendments
Authors: Voorhees M. E. , Trlica M. J. , Uresk D. W. 
Published: July 2010

AbstractThis study was conducted to evaluate the effects of spoil amendments on growth of the dominant invader of bentonite mine spoil, Atriplex suckleyi (Torrey) Rydb. an annual, commonly known as rillscale. Application of amendments in the fall had a greater positive effect on growth of rillscale than application of amendments in the spring. Amendment with sawdust, alone or in combination with other amendments, increased growth of rillscale through at least two growing seasons. Amendments of gypsum and inorganic fertilizer alone had little effect on plant growth, but the highest production of rillscale (3500 kg/ha) was achieved on spoil that had been treated in the fall with a combination of gypsum, sawdust (with N), and fertilizer (N, P, and K) amendments. High production capabilities and degree of response to spoil treatment support the hypothesis that rillscale could be useful for early revegetation of bentonite mine spoil.
Solution Composition Effects on Cadmium Sorption by Forest Soil Profiles
Authors: Homann Peter S. , Zasoski Robert J. 
Published: July 2010

AbstractCadmium sorption can reduce Cd transport through sewage sludge‐amended forest soils. Three mineral soil horizons from each of six western Washington State soil series were evaluated for their potential to sorb Cd. Horizons varied in pH from 3.6 to 6.4, in clay content from 100 to 470 g kg−1, in organic C from 3 to 87 g kg−1, and in cation exchange capacity from 1.8 to 35.8 cmolc kg−1. Batch equilibrium experiments were conducted in three background solutions (calcium nitrate, calcium sulfate, and sodium sulfate) that had ionic strengths of 0.016 and were maintained at pH values close to the natural soil pH. Between 4 and 97% of the initial 10 µM Cd was sorbed by 1 g soil in 0.1‐L background solution. Sorption varied among the horizons in each soil profile, but there was no consistent trend with depth among the six profiles. Sorption did not differ significantly between calcium nitrate and calcium sulfate solutions. However, it was significantly lower in calcium sulfate than sodium sulfate solution, supporting the hypothesis that calcium competition lowers Cd sorption. The amount of Cd sorbed when a solution concentration of 1 µM free Cd2+ is maintained (Cdsorbed) decreased 81% when free Ca2+ increased from 0.09 mM Ca2+ in sodium sulfate to 4.0 mM Ca2+ in calcium sulfate solution. The Cdsorbed increased with increased natural soil pH. A horizons had higher Cdsorbed than B horizons of similar natural soil pH, possibly due to their higher organic matter contents.
Cadmium and Zinc Availability to Corn following Termination of Sewage Sludge Applications
Authors: Bidwell A. M. , Dowdy R. H. 
Published: July 2010

AbstractTo assess the availability of sludge‐borne Cd and Zn over time, corn (Zea mays L.) and soil (Typic Hapludoll silt loam) were sampled for 6 yr following termination of three annual applications of sewage sludge. Cumulative sludge applications totaled 0, 60, 120, and 180 Mg ha−1. Sludge treatments consistently resulted in greater Cd and Zn accumulation in stover than did the control treatment for each of the 6 yr following the final sludge application. Cadmium and Zn concentration in stover increased linearly within treatment levels for all years. Concentrations of Cr, Cu, Ni, and Pb in stover and grain fluctuated annually, with no predictable effect of sludge rate. Of the metals measured in stover and grain, only stover Cd exceeded the suggested National Research Council tolerance level of 0.5 mg kg−1 in animal feed for all sludge treatments in all years. Cadmium uptake decreased over time at all sludge rates, and was inversely related (P > 0.01) to time in years following terminal application. Zinc uptake declined slightly over time, although not to the same degree or with the same predictability as Cd uptake. Soil Cd and Zn extractable with DTPA and 1 M HNO3 were highly correlated with plant metal uptake within years. However, metal uptake diminished with consecutive croppings for constant levels of extractable Cd and Zn. Hence, the reliability of either DTPA or 1 M HNO3 in the prediction of Cd and Zn uptake in subsequent croppings is questionable.