bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Transformations in a Waterhyacinth‐based Water Treatment System
Authors: Moorhead K. K. , Reddy K. R. , Graetz D. A. 
Published: July 2010

AbstractFate of added 15NH4‐N and 15NO3‐N in waterhyacinth [Eichhornia crassipes (Mart.) Solms]‐based water treatment system was evaluated under controlled conditions. Labeled 15NH4‐N uptake by waterhyacinth exceeded 15NO3‐N uptake. Total 15N recovery by waterhyacinth ranged from 57 to 72% for added 15NO3‐N and 70 to 89% for added 15NH4‐N. Both sediment and detritus were potential sources of N for waterhyacinths. Waterhyacinths cultured in sewage effluent removed 55% of the added 15NH4‐N and 14% of the added 15NO3‐N, respectively. Three to 44% of the added 15NH4‐N was lost through nitrification in the water column and subsequent denitrification in the underlying sediments, whereas 24 to 86% of the added 15NO3‐N was lost through denitrification. In a system without plants, 13 to 89% of the added 15NH4‐N and 48 to 96% of the added 15NO3‐N were lost from the system through a combination of nitrification/denitrification and NH3 volatilization.
Cation Cycling in a Base‐poor and Base‐rich Northern Hardwood Forest Ecosystem
Authors: Thorne J. F. , Anderson J. E. , Horiuchi K. M. 
Published: July 2010

AbstractBiogeochemical cycles of Ca, Mg, K, and Na were studied in a small forested watershed on relatively base‐rich terrain at the Sleepers River Research Watersheds (SRRW) in northeastern Vermont and on base‐poor terrain at the Hubbard Brook Experimental Forest (HBEF) in central New Hampshire. The two watersheds are comparable except that shallower soils at the SRRW are weathered from calcareous and quartz mica schist till, whereas the deeper soils at the HBEF are weathered from schist, gneiss, and quartz monzonite till. Inputs of the four cations in precipitation were similar except for Ca; Ca inputs were an order of magnitude greater at the SRRW. Total annual cation outputs were more strongly related to total stream flow and parent material geochemistry than to cation inputs in precipitation. Analysis of the variation in cation output in stream water with respect to flow suggests strong geochemical control of cation output at the SRRW. Similar analysis of data from the HBEF suggests a more complex pattern of cation output related to biological cycling of cations. Inputs of acidity may serve to flush the soil at the HBEF of cations.
Longitudinal Variations in Trace Metal Concentrations in a Northern Forested Ecosystem
Authors: Driscoll C. T. , Fuller R. D. , Simone D. M. 
Published: July 2010

AbstractLongitudinal variations in the concentrations of four trace metals (Fe, Pb, Mn, and Zn) in soil solutions and streamwater were investigated at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. The soils at Hubbard Brook are well‐drained Spodosols. Concentrations of Pb and dissolved organic carbon (DOC) were elevated in soil solutions draining organic (Oa) horizons both in coniferous (red spruce, Picea rubens; balsam fir, Abies balsamea) and northern hardwood (yellow birch, Betula alleghaniensis; American beech, Fagus grandifolia; sugar maple, Acer saccharum) stands. In the coniferous zone, concentrations of Pb were high in streamwater, while DOC and Fe concentrations were elevated in the lower mineral soil (Bs2) solutions and streamwater. In hardwood stands, reduced DOC concentrations in Bs2 soil solutions and streamwater relative to Oa horizon concentrations coincided with lower concentrations of Fe and Pb, and apparent retention of these solutes in the mineral soil. Concentrations of Pb and Fe were highly correlated with DOC in soil solutions and streamwater suggesting that mobilization/immobilization of Pb and Fe were predominately controlled by transfer of DOC through complexation reactions. In contrast, concentrations of Mn and Zn were highest in streams and soil solutions in high‐elevation hardwood stands. Elevated concentrations in deciduous vegetation and patterns of solution concentration suggest that vegetative cycling may be important in regulating transfer of Mn. Results of this study indicate that hydrologic pathways, vegetation, and soil characteristics related to hillslope position all contribute to regulate trace metal concentration in drainage waters. As a result, considerable variability in trace metal transport is evident within a relatively small catchment.
Combined Effects of Ozone and Water Stress on Alfalfa Growth and Yield
Authors: Temple P. J. , Benoit L. F. , Lennox R. W. , Reagan C. A. , Taylor O. C. 
Published: July 2010

AbstractA 2‐yr study (1984 and 1985) designed to determine the interactive effects of ozone (O3) and water stress on alfalfa (Medicago sativa L. cv. WL‐514) was conducted in Shafter, CA. The objectives of this study were to develop O3 dose‐yield response functions for alfalfa, to determine how water stress could alter these functions, and to describe the cumulative effects of multiple‐year exposures to O3 on this perennial crop. Field‐grown alfalfa, raised under normally irrigated (NI) or water‐stressed (WS) conditions in open‐top chambers, was exposed to five O3 treatments including charcoal‐filtered (CF), nonfiltered (NF), NF plus an additional 33, 67, or 100% of ambient O3 concentrations (NF × 1.3, NF × 1.7, and NF × 2.0, respectively). Ambient O3 concentrations averaged 0.049 µL L−1 in 1984 and 0.042 µL L−1 in 1985 for the seasonal 12‐h (0900–2100) means from April to October. Water stress reduced total seasonal yield about 10% in 1984 and 27% in 1985. Ozone significantly reduced yields in both years, and the interaction between O3 and water stress was statistically significant in 1985 and for combined 1984 and 1985 years. Seasonal yields for 1985 in NI plots were reduced 0, 14.9, 24.3, and 24.9% in NF, NF × 1.3, NH × 1.7, and NF × 2.0 treatments, respectively. Comparable seasonal yield reductions in WS plots were 5.9, 7.2, 13.5, and 18.1%. Ozone dose‐alfalfa yield loss functions were homogeneous between 1984 and 1985 and no evidence of a cumulative effect of multiple‐year exposure to O3 was found on top growth. However, crown (underground stem) weights were significantly reduced by O3, suggesting that continued exposure to O3 could shorten the productive life of alfalfa stands, in addition to its effect on yield.
Influence of Overwatering and Fertilization on Nitrogen Losses from Home Lawns
Authors: Morton T. G. , Gold A. J. , Sullivan W. M. 
Published: July 2010

AbstractFertilized home lawns represent a potential source of NO3‐N contamination to groundwater and surface waters. The waterborne losses of inorganic N from Kentucky bluegrass (Poa pratensis L.) turf subjected to three levels of N fertilization (0, 97, and 244 kg N ha−1 yr−1 as urea and methylene urea) and two irrigation regimes (scheduled by tensiometer and overwatering with 3.75 cm of water per week in addition to rainfall) were measured. The site was located on a Merrimac sandy loam (sandy, mixed, mesic Typic Dystrochrept). Soil‐water percolate was collected by suction plate lysimeters placed below the root zone. Surface runoff was quantified with orifice flow splitters. Soilwater percolate flux comprised >93% of the total water and inorganic‐N discharged from all treatments. Mean annual flow weighted concentrations of inorganic N in soil‐water percolate were below the U.S. drinking water standard on all treatments and ranged from 0.36 mg L−1 on the overwatered, unfertilized, control treatment to 4.02 mg L−1 on the overwatered, high N treatment. Annual losses ranged from 32 kg ha−1 on the overwatered high N rate treatment to 2 kg ha−1 on the scheduled irrigation, unfertilized, control treatment. Overwatering in conjunction with fertilization generated significantly higher annual flow weighted concentrations and mass loss than the unfertilized controls. Nitrogen loss and concentrations from the scheduled irrigation treatments were not significantly different from the controls.
Soil Water Depletion Under Crops on Reclaimed and Undisturbed Soils
Authors: Schroeder S. A. , Halvorson G. A. 
Published: July 2010

AbstractSoil water depletion by profile depth increments and total water usage were measured yearly under either small grains or corn (Zea mays L.) over a 4‐yr period on undisturbed Williams loam (fine‐loamy, mixed Typic Argiborolls) and soil reclaimed following simulated stripmining. The reclaimed soil had topsoil thicknesses of either 0.23, 0.46, or 0.69 m respread over nonsaline, nonsodic spoil materials whose textures were gravelly loamy sand with and without a clay loam subsoil, clay loam, or silty clay loam. Total water usage and soil water depletion (for profile depths of 0 to 0.6 m and 0.6 to 1.5 m) were consistently greater, but essentially significant (P = 0.10) only in 1 yr, for the undisturbed compared to the reclaimed soil (averaged over topsoil thickness or spoil texture). Grain or biomass yields were significantly higher for the undisturbed compared with the reclaimed soil when growing‐season precipitation was inadequate or poorly distributed. Shallower rooting depths and thus lesser soil water depletion even though the reclaimed soil had similar amounts of plant‐available soil water at planting for 3 of the 4 yr resulted in water stress conditions and reduced potential productivity in inadequate precipitation years on the reclaimed soil. Similar water‐use efficiency values were found for both the undisturbed and reclaimed soils for all 4 yr. If amounts of available soil water at planting and soil water depletion values had been more uniform between the undisturbed and reclaimed soils, the reclaimed soil most likely would have met the reclamation law requirement of “equal or better than” productivity present prior to mining (undisturbed soil productivity) for all 4 yr.
Determination of 1,2‐Dibromoethane (EDB) in Field Soils: Implications for Volatile Organic Compounds
Authors: Sawhney B. L. , Pignatello J. J. , Steinberg S. M. 
Published: July 2010

AbstractA method is described for determining 1,2‐dibromoethane (EDB) in soils previously fumigated with EDB. The procedure involves extraction of soil with methanol at 75°C for 24 h in a sealed vial, followed by gas chromatographic analysis of the extract. Reproducibility of the method was demonstrated using replicated samples by separate analysts, and the detection limit was ≤1.8 µg kg−1. Acetone and acetonitrile were as efficient. Other published methods for determining volatile organic compounds (VOCs) in soils and sediments gave very low recoveries relative to the above method. A purge and trap method (EPA Method 8240) released less than 10% EDB, even at higher temperatures and longer purge times than recommended. Thermal desorption from soil columns with a stream of N2 at 100 to 200°C resulted in decomposition rather than desorption of EDB. By contrast, a freshly added spike was recovered quantitatively at these temperatures. Two other methods, sonication‐extraction and Soxhlet extraction, which are commonly used for nonvolatile and semivolatile compounds in soil, also gave low recoveries of EDB from the fumigated field soils. The vigorous conditions needed to extract a labile compound like EDB are consistent with our previous findings that EDB in the field samples is trapped in soil micropores from which diffusive release is slow.
Nitrogen Cycling in a Multiple‐Crop Vegetable Production System
Authors: Lowrance Richard , Smittle Doyle 
Published: July 2010

AbstractDenitrification losses of N and crop uptake of N were measured in intensive vegetable crop production systems on a Bonifay sand soil (loamy, siliceous, thermic, grossarenic Plinthic Paleudults) in the Georgia Coastal Plain. Nitrogen uptake efficiencies for total aboveground biomass averaged 59% of N applied to crops, but only 28% of fertilizer N was removed in crop harvest. Over the course of the study, a total of 388 kg ha−1 of N fertilizer was applied and a total of 90 kg ha−1 was removed in crop harvest. Most of the remainder of the fertilizer N (about 290 kg ha−1) was available for leaching as nitrate (NO3). Even though N fertilization rates were high, denitrification rates were low, <2 kg ha−1 yr−1. Additions of nitrate and glucose to undisturbed soil cores showed that denitrification was limited by C availability and by lack of anaerobic conditions in the field. In the first year of the study, denitrification rates before fertilizer addition and irrigation were higher than after. The method of fertilizer application (broadcast vs. applied in irrigation water) had no effect on denitrification rates or crop N uptake.
Aquatic Weed Biomass Disposal: Effect on Soil Organic Matter
Authors: Tate Robert L. , Riemer Donald N. 
Published: July 2010

AbstractAquatic weed biomass was amended to field plots of a Freehold sandy loam (Typic Hapludults) either as a mulch or incorporated into the surface soil with the objective of determining the potential for using soil as a repository for excess weed biomass and for using this biomass to augment soil organic matter levels and associated biological processes. Potential and actual dehydrogenase activities, soil organic C, total Kjeldahl N, and the C/N ratio of the soil were measured. Tomato plants (Lycopersicon esculentum Mill.) were grown in the plots. Amendment of the soil with aquatic weeds annually for up to 3 yr resulted in two‐ to threefold increases in actual and potential dehydrogenase and total Kjeldahl N. No consistent effect of inclusion of nitrogenous fertilizer with the aquatic weed amendments was detected. Analysis of the data with multiple linear regression techniques indicated that total Kjeldahl N and soil moisture were major controllers of both potential and actual dehydrogenase activities. This study suggests that aquatic weeds, whether added as a mulch or incorporated into the surface of the soil profile, have little effect on soil C, at least in the short run, but have a positive impact on the ecosystem through augmentation of the soil organic N pools and increased microbial activity.
Retention of Metals by Several Soils of the Southeastern United States
Authors: King Larry D. 
Published: July 2010

AbstractMetals in municipal and industrial wastes can cause toxicities in plants and Cd can accumulate to concentrations that pose a health hazard for livestock and humans. Therefore, soil properties important in reducing plant availability of metals must be identified. The capacity of a soil to remove metals from solution is one estimate of the effect of that soil on metal availability to plants. Thirty five milliliter volumes of separate solutions of Cd (0.18 mol m−3), Co (0.34 mol m−3), Cr (0.77 mol m−3), Cu (1.10 mol m−3), Ni (0.34 mol m−3), Pb (0.97 mol m−3), Sb (1.64 mol m−3), and Zn (0.61 mol m−3) were equilibrated for 6 d with 5‐g samples of soil from the A horizons and some B horizons of 10 mineral and three organic soils (21 samples). Total removal from solution (sorption) was determined. The samples then were extracted with 1 M KCl so the quantity of nonexchangeable metal could be determined. The respective ranges of sorbed and nonexchangeable metal, expressed as a percentage of the total quantity of metal in the initial solution, were: Cd 0–90, 0–55; Co 15–93, 1–89; Cr 31–100, 22–100; Cu 36–100, 13–100; Ni 12–95, 5–82; Pb 31–100, 14–98; Sb 50–100, 42–99; Zn 13–98, 5–94. Stepwise multiple regression was performed (on mineral soils only) using sand; silt; clay; pH; cation exchange capacity (CEC); exchangeable cations; organic matter; dithonite‐extractable Al and Fe; and ammonium oxalate‐extractable Al, Fe, and Mn as independent variables and the quantity of sorbed or nonexchangeable metal as the dependent variable. Sorbed and nonexchangeable Cd, Co, Cu, Ni, and Zn were related mainly to soil pH or dithonite‐extractable Fe (Fed). Sorbed and nonexchangeable Cr, Pb, and Sb were related mainly to Fed, ammonium oxalate‐extractable Fe, Sand, or clay. Relative retention of metals by soil was in the order Pb > Sb > Cu > Cr > Zn > Ni > Co > Cd. Although CEC is widely used in regulations governing metal loading rates on agricultural land, the results of this study indicate that Fe oxides and clay content would be better parameters to use for soils of the southeastern USA.
Effect of Selected Soil Properties on Cadmium Content of Tobacco
Authors: King Larry D. 
Published: July 2010

AbstractIn a greenhouse study, limed and unlimed soil from the A horizon of six mineral soils and three organic soils of the southeastern USA was amended with 0, 1, 2, and 4 kg Cd ha−1 as CdCl2 (1.8, 3.6, and 7.2 mg Cd pot−1). Tobacco (Nicotiana tabacum L.) was grown until flower initiation (42 d). The 2‐ and 4‐kg Cd rates reduced dry weight on the Norfolk soil (Typic Paieudult), but Cd had no effect on dry weight on the other soils. Cadmium concentration was a maximum in the lower leaves and decreased with leaf position up the stalk. At the 2‐kg Cd rate, liming reduced leaf Cd concentration in only three soils. Lack of liming effect in the other soils was thought to be a result of high organic matter, high initial pH, or small pH changes effected by the lime. Lime reduced the effects of Cd loading rate and soil types on Cd concentration in tobacco. Stepwise multiple regression was used to relate soil properties to leaf Cd concentration and removal of Cd by tobacco harvest. When organic and mineral soils were considered together, leaf Cd and Cd removal were best related to the Cd sorptive capacity of the soils as determined in previous studies (Cd removed from a Cd solution or sorbed Cd not removed with 1 M KCl). When only the mineral soils were considered, inherent soil properties like sand content, ammonium oxalate‐extractable Fe (Feo), and pH dominated the regression models. With limed mineral soils (pH 5.7–7.0), models for leaf Cd and Cd removal contained pH, Feo, and/or ammonium oxalate‐extractable Cd. Model‐calculated values and actual values differed by only ±4% so the models should be useful in ranking soils from the southeastern USA for their capacity to retain salt sources of Cd. Soil cation exchange capacity, which is used to regulate Cd loading rates on agricultural soils, did not appear in any of the models.
Soil Salinity and Ambient Ozone: Lack of Stress Interaction for Field‐Grown Alfalfa
Authors: Olszyk David M. , Maas Eugene V. , Kats Gerrit , Francois Leland E. 
Published: July 2010

AbstractThe interaction of ambient photochemical oxidants (primarily ozone, O3) and salinity on vegetation was evaluated in the field for ‘U.C. Salton’ and ‘Moapa’ alfalfa (Medicago sativa L.). Salinity treatments were imposed by irrigating with waters having average electrical conductivities of 0.9, 3.4, and 6.3 dS m−1, which resulted in mean saturated‐soil extract conductivities in the root zone of approximately 1.5, 5.8, and 8.1 dS m−1, respectively. Plants were exposed in open‐top chambers to filtered or unfiltered air at ambient O3 concentrations during three regrowth periods, and filtered or unfiltered air plus added O3 during a fourth. No overall interaction between O3 and salinity occurred for alfalfa growth or yield. The only general effect of O3 itself was to increase the percent empty nodes at three of the four harvests. Percent empty nodes due to ozone tended to decrease with increasing salinity, but the interaction was statistically significant only for the second harvest. Salinity by itself was more detrimental to plants than O3, causing occasional decreases in dry weight and height. Large differences in growth and yield occurred between the two cultivars, but they were not associated with O3 or salinity sensitivity. At the levels tested, salinity would affect plants more than O3 in areas where both stresses occur.
Sewage Sludge‐Soil Interactions as Measured by Plant and Soil Chemical Composition
Authors: Hue N. V. , Silva J. A. , Arifin R. 
Published: July 2010

AbstractThe utilization of sewage sludge on agricultural lands requires prior knowledge of the interactions among sludge, soil, and plant. A green house experiment was conducted on three mineralogically different soils: a limed, volcanic ash‐derived Andept (Akaka series, thixotropic, isomesic Typic Hydrandepts), an alkaline Vertisol (Lualualei series, very‐fine, montmorillonitic, isohyperthermic Typic Chromusterts) and a limed, manganiferous Oxisol (Wahiawa series, clayey, kaolinitic, isohyperthermic Tropeptic Eutrustox). Each soil received four rates (0, 45, 90, and 180 Mg ha−1) of a Honolulu sewage sludge, and an N‐P‐K fertilizer treatment. Lettuce (Lactuca sativa L.) was grown as a test crop. Concentrations of plant Cu and Fe were not significantly affected by sludge rate; plant Cd and Zn concentrations increased as sludge rate increased regardless of soil type. Plant Ni remained essentially constant as sludge rate increased in two of the soils; in the Oxisol, plant Ni increased with increasing sludge rate. Manganese in the soil solution drastically increased with sludge rate, and became phytotoxic (plant Mn exceeded 700 mg kg−1, a level above which significant yield reduction occurred) with increasing sludge addition in the Oxisol, and with 180 Mg ha−1 in the Vertisol. The Andept, with its high adsorption capacity, retained most of the heavy metals added by the sludge; this soil also retained phosphate so strongly that P was the growth‐limiting factor in all treatments as indicated by low dry‐matter yields, low plant P (<1.4 vs. 4.0 mg kg−1 for maximum yield) and by low soil‐solution P concentration (<0.08 vs. 0.40 mg P L−1). In terms of heavy metal accumulation in plants, it appeared that the Andept could tolerate the highest sludge loading rate, and the Oxisol the lowest.
Effect of Meteorological Parameters on Ammonia Loss from Manure in the Field
Authors: Brunke R. , Alvo P. , Schuepp P. , Gordon R. 
Published: July 2010

AbstractA micrometeorological flux measuring technique was used to determine ammonia (NH3) volatilization from surface‐applied swine (Sus scrofa) and dairy (Bos taurus) manure under precipitation‐free June to October weather conditions. An attempt to correlate observed volatilization rates of NH3 to single meteorological parameters such as windspeed, temperature, net radiation, etc. was inconclusive insofar as these variables are not independent under field conditions; correlations with windspeed and net radiation appeared generally high. An approximate linear relationship was obtained, however, between applied total N or ammoniacal‐N and NH3 flux within the meteorological conditions encountered during the experiments. This is consistent with the assumption that volatilization from liquid manure is primarily determined by the drying rate of the manure insofar as partial pressure of NH3 is the primary parameter determining volatilization. A derived meteorological variable such as the hay drying index already used in some network agrometeorological forecasts may thus be the most suitable single indicator of high‐volatilization weather conditions.
A Dual‐Buffer Titration Method for Lime Requirement of Acid Minesoils
Authors: Harper W. S. , Baker D. E. , McCormick L. H. 
Published: July 2010

AbstractA lime requirement test termed the dual‐buffer titration (DBT) was developed for acid minesoils occurring in Pennsylvania. The DBT uses two buffers to stoichiometrically account for contributions of hydrogen ions (H+) to soil acidity to pH 7.0, including those from the hydrolysis of Al. The first buffer lowers the soil pH to 3.17 to dissolve Al‐OH polymers, amorphous coatings, and interlayer species. The second buffer raises the pH to approximately 8.2, titrating the exchangeable Al3+ and other hydrolyzed species to neutralized forms. Lastly, a titration of the buffers‐soil mixture with standardized base to pH 8.2 provides a direct measure of the lime requirement. For comparison, a 5‐month CaCO3 incubation of 31 soils was also determined. The results by the two methods were highly correlated (r = 0.92) for 24 samples and statistically the same at a probability level of 0.001.