bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen Transformations in a Waterhyacinth‐based Water Treatment System
Authors: Moorhead K. K. , Reddy K. R. , Graetz D. A.
Published: July 2010

Fate 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

Biogeochemical 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

Longitudinal 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

A 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

Fertilized 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

Soil 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

A 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

Denitrification 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

Aquatic 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

Metals 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

In 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

The 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

The 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

A 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

A 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.
Toxicity of Alkyllead Salts to Anaerobic Nitrogen Transformations in Sediment
Authors: Blais Jean Simon , Marshall William D. , Knowles Roger
Published: July 2010

Four alkyllead chlorides (Me3PbCl, Me2PbCl2, Et3PbCl, Et2PbCl2; Me = CH3, Et = C2H5) were separately tested (at 0.1, 1.0, 5.0, and 10.0 µg L−1) for their inhibitory properties against denitrification and N2 fixation in a lake sediment as determined by acetylene blockage and acetylene reduction techniques. In the presence of added nitrate, glucose, and acetylene, alkyllead salts only moderately inhibited nitrous oxide, ethylene, and carbon dioxide accumulation by whole slurry incubations. These effects were more pronounced in supernatant from sediment. In general, ethylleads were more toxic than methyllead salts and dialkylleads were more inhibitory than their trialkyl homologs to these transformations. Successive incubations indicated that microbes adapted to the presence of these toxicants, a phenomenon also observed with other heavy metals. At the highest concentrations, which have been reported in sediments, no serious hazard to N transformations exists.
Seasonal Trends of Aluminum Chemistry in a Second‐Order Massachusetts Stream
Authors: McAvoy Drew C.
Published: July 2010

An investigation of streamwater chemistry was conducted to evaluate seasonal and spatial variations of Al in an acid‐sensitive watershed. Monthly grab samples were collected from three stream sites along the West Wachusett Brook, MA, and analyzed for all major solutes from March 1985 to January 1986. Total monomeric Al concentrations were greatest during high runoff periods with values as high as 22 and 11 µM in upland and wetland runoff, respectively. Survey results also illustrated the importance of ionic solute concentrations to the mobility and transport of Al. The mountain stream showed that basic cation dilution was an important factor contributing to greater Al transport during high flow periods. In contrast, organic acids in the wetland stream served as a mobile anion, and thus greatly affected Al transport by complexation and charge balance effects. Solubility with an aluminum hydroxide mineral phase did not appear to be a controlling factor of streamwater Al concentrations throughout the year. Results from a chemical equilibrium model showed the mountain stream to be potentially toxic to fish during high‐flow periods, whereas the wetland stream, being dominated by organo‐Al complexes, had a minimal potential for toxicological effects.
Fate of Trifluralin and Triallate Applied as a Mixture to a Wheat Field
Authors: Grover R. , Smith A. E. , Shewchuk S. R. , Cessna A.J. , Hunter J.H.
Published: July 2010

Dissipation of triallate [S‐(2,3,3‐trichloroallyl) diisopropylthiocarbamate] and trifluralin (a,a,a‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) in air and soil was measured following their application as a pre‐emergence treatment to a wheat (Triticum aestivum L.) field. Drift losses during application and incorporation were less than 1% of the amounts applied. Air samples, collected at six heights ranging from 30 to 200 cm above the soil surface initially and then above the crop canopy following emergence during the 67 d after application, showed distinct gradients of each herbicide in the air, with the highest concentrations in samples closest to the ground. The highest flux rates for triallate and trifluralin were 4 and 3 g ha−1 h−1 during the 4‐ to 6‐h period after application, when the concentrations at 30 cm were 2500 and 1700 ng m−3, respectively. Fluxes of both herbicides decreased with time, but were dependent mainly on soil moisture conditions. The total vapor losses for the 67‐d sampling period were 17.6 and 23.7% triallate and trifluralin, respectively. About half of these losses were in the first week. There were three distinct phases in the dissipation of both herbicides from the soil. The initial rapid phase, with vapor losses as the major route (Phase I), was followed by slow and continual dissipation over the entire growing season (Phase II), with volatilization and degradation as the potential pathways of dissipation. The third phase with little or no dissipation was reflective of the Canadian winter conditions. The gross dissipation of both herbicides during Phases I and II, however, followed the first‐order rate equation, with half‐concentration time of 88 ± 7 and 99 ± 9 d for triallate and trifluralin, respectively, with volatilization as the dominant process during Phase I.
Effects of Ozone and Sulfur Dioxide on Yield of Red Clover and Timothy
Authors: Kohut Robert J. , Laurence John A. , Amundson Robert G.
Published: July 2010

Although red clover (Trifolium pratense L.) and timothy (Phleum pratense L.) are important crops in the northeast, little is known about their responses to air pollution in the field. A crop of red clover and timothy was exposed to O3 and SO2, both alone and in combination, in open‐top chambers to evaluate effects on yield. Ozone treatments were charcoal‐filtered air, nonfiltered air, and nonfiltered air to which O3 was added to maintain concentrations 1.5 and 2.0 times ambient. Sulfur dioxide treatments were ambient and three levels of addition that simulated the concentrations and dynamics of exposures near point sources of the pollutant. Yield was based on the total biomass obtained in two harvests each year. Two studies were conducted in consecutive years. Sulfur dioxide had no effect on yield and there were no interactions between the pollutants in either study. In the first year, O3 produced no effects on timothy but reduced the yield of clover and, consequently, the yield of the combined species. Red clover was less prevalent in the stand in the second year and O3 had no detectable impact on the yield of clover or on total yield since the stand was dominated by the O3‐resistant timothy. The two studies indicated that effect of O3 on yield was a function of both the concentration of the pollutant and the relative O3‐sensitivity and prevalence in the stand of the component species.
Municipal Sludge for Minespoil Reclamation: I. Effects on Microbial Populations and Activity
Authors: Seaker E. M. , Sopper W. E.
Published: July 2010

A field study of five coal surface mine sites reclaimed with sewage sludge and one site reclaimed by conventional methods (chemical fertilizer) was conducted to assess the effects of sludge amendments and time on populations of bacteria, fungi, and actinomycetes, and on microbial respiration and organic matter decomposition. The sludge‐amended sites ranged in age from 1 to 5 yr following sludge application at rates of 120 to 134 Mg ha−1 (dry wt. basis). All sites were planted to grass and legume cover. Populations of aerobic heterotrophic bacteria, fungi, and Nitrobacter, and soil respiration rate, were highest on the 1‐yr‐old site due to the high organic matter input. On the four older sites, values decreased, but remained within the ranges reported for undisturbed soils. Actinomycete populations peaked on the 3‐ and 4‐yr‐old sites, while populations of Nitrosomonas were not related to the age of the site. Decomposition rate was lowest on the 1‐yr‐old site, and increased significantly with site age. As measured by microbial populations and activity, ecosystem recovery on the sludge‐amended sites appeared to be occurring at a more rapid rate than on the fertilizer‐amended site, which after 5 yr, exhibited sparse microbial populations and low activity. The microbial populations in the sludge‐amended spoil were not adversely affected by the heavy metals applied in the sludge, when compared with populations of soil microbes reported for undisturbed soils.
Wet Deposition Estimates from Long‐Term Bulk and Event Wet‐Only Samples of Incident Precipitation and Throughfall
Authors: Richter D. D. , Lindberg S. E.
Published: July 2010

This report describes a 2‐yr study comparing two sampling systems that are used to measure major ionic constituents in incident precipitation and canopy throughfall: long‐term bulk sampling vs. event‐based, wet‐only sampling. Major deviations in chemical concentrations (SO2−4, NO−3, K+, Ca2+, and H+) were documented between the two sampling systems, deviations that were ion‐specific in both incident precipitation and throughfall. Differences in chemical concentrations between the two sampling systems were greater (i) during the growing than during the dormant seasons, and (ii) for incident precipitation (collected in the open) than for throughfall under chestnut oak forest (Quercus prinus L.) canopies. Nutrient‐cycling processes in forests may be misinterpreted if flux data are based solely on long‐term bulk samplers of incident precipitation and canopy throughfall. For example, comparison of bulk and wet‐only throughfall solutions suggests that when bulk samplers collect throughfall under hardwood canopies, the ability of hardwood canopies to increase pH of low pH precipitation may be overestimated.
A Pilot‐Scale Evaluation of Alum Treatments to Reduce Lake Sediment Phosphorus Release
Authors: Young Thomas C. , Collins Anthony G. , Armstrong Robert A.
Published: July 2010

Presented is a simple mass‐balance approach to evaluating alum inactivation of sediment‐bound phosphorus (P) using continuous‐flow reactors and aerobic sediments from a eutrophic luke (Black Lake, NY). The method permitted tests of treatment effects on the rate and duration of sediment P release, was simple to interpret, statistically reliable, and could be applied to other eutrophic systems. Analyzed as a zero‐order process, sediment P release rate decreased linearly as a function of alum dose, and the maximum dose tested (equivalent to 1.22 g Al m−2) halved the zero‐order P release rate for four hydraulic retention periods.
Spatial Variability of Phosphate Adsorption Parameters
Authors: van der Zee S. E. A. T. M. , Nederlof M. M. , van Riemsdijk W. H. , de Haan F. A. M.
Published: July 2010

Reversible phosphate (designated P) adsorption for acid soils with a narrow pH range is described with the Langmuir kinetics equation. Using a combination of two experimental desorption techniques, i.e., desorption in water and desorption in the presence of an “infinite” sink for P, respectively, the adsorption maximum (Qm) and the adsorption constant (K) were assessed for soils (pre‐)saturated with P. The adsorption maximum was proportional with the sum of oxalate‐extractable Fe and Al (ME) (i.e., Qm ≈ 0.135 ME), for topsoil samples from a field and a watershed. The K values found for the field and for the watershed samples were in the same order of magnitude (K = 15−25 L mmoL−1). The adsorption maximum and the adsorption constant, as well as the amounts of P desorbed, were spatial variates. The distributions were fitted to the normal as well as the lognormal distribution at the significance level of 0.05, using the Kolmogorov‐Smirnov test statistic.
Phosphorus and Potassium Relationships in Southwestern Virginia Coal‐Mine Spoils
Authors: Howard J. L. , Amos D. F. , Daniels W. L.
Published: July 2010

Nutrient deficiencies are commonly reported as a major limiting factor in reclaiming Appalachian surface‐mine spoils. Our objective was to intensively study the P and K relationships of representative mine spoils and contiguous natural soils derived from the Wise Formation in southwestern Virginia. Quantity/intensity (Q/I) relationships for P and K were developed for the major occurring spoils and representative natural soil materials. Sandstones (sublitharenites) and siltstones dominate the Wise Formation and show three phases of cementation—an initial carbonate phase, a second goethite phase, and a third silica overgrowth phase. Total P ranged from 255 to 530 mg/kg in the dominant sandstone and siltstone spoil types, and the majority of P was associated with complex carbonates. Phosphorus in the weathered natural soil materials was dominantly associated with Fe oxides. Phosphorus Q/I analyses coupled with P fractionation data indicate that fixation by Fe oxides is the most likely cause of P deficiencies in rock spoils derived from the Wise Formation and may be a widespread problem limiting revegetation and reclamation success in the Appalachian region. This problem is difficult to rectify by fertilization; hence, Fe oxide‐rich strata, and spoils derived from them, should be avoided during regrading to optimize surface mine reclamation. Micas and traces of feldspars are the dominant sources of K in the mine spoils. Potassium fixation by weathered mica occurs in natural soils derived from the Wise Formation, but not in unweathered spoils. Nonferruginous rock substitutes for topsoil are therefore superior as a plant growth medium in regard to P and K availability.
Desorption of Atrazine and Cyanazine from Soil
Authors: Clay S. A. , Allmaras R. R. , Koskinen W. C. , Wyse D. L.
Published: July 2010

Removal of soluble soil organic carbon (SSOC) during herbicide desorption studies using the batch equilibration method may affect the herbicide‐soil‐solution equilibrium particularly if herbicide‐SSOC complexes can form. Desorption characteristics of atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine) and cyanazine (2‐{[4‐chloro‐6‐(ethylamino)‐s‐triazine‐2‐yl]amino}‐2‐methylpropionitrile] were determined in a Ves clay loam (Aquic Hapludolls). For adsorption, the soil was equilibrated with 0.01 M CaCl2 solutions containing atrazine or cyanazine. Desorption with 0.01 M CaCl2 each day for 5 d resulted in hysteresis when compared to the adsorption isotherm. Replacement of the equilibration solution with soil extract for 5 d, while maintaining a higher SSOC content in the desorption equilibration solution than did the CaCl2 solution, did not change desorption isotherm equations. The SSOC‐herbicide complexes were not detected in any of the adsorption and desorption equilibration solutions by ultrafiltration (membranes with molecular mass cut offs of 10 000 and 500 daltons), HPLC, or TLC techniques. Either s‐triazine‐SSOC complexes were not formed in sufficient quantities or they were not stable enough to affect desorption of the herbicide during batch equilibration.
Dissolved Oxygen Requirements for the Indirect Photolysis Treatment of Two Refractory Herbicides
Authors: Watts Richard J. , Adams V. Dean , Middlebrooks E. Joe
Published: July 2010

Indirect photolysis in lagoons under solar radiation has been proposed for the treatment of pesticide‐laden agricultural runoff, pesticide container rinsate, and industrial wastes. A common indirect photolysis mechanism, singlet oxygen generation, consumes oxygen through electrophilic attack on the organic waste components. Photolysis lagoons will require optimum oxygen input to achieve economical treatment. Dissolved oxygen requirements were investigated for the photolysis of bromacil (5‐bromo‐3‐sec‐butyl‐6‐methyluracil) sensitized by methylene blue and terbacil (3‐tert‐butyl‐5‐chloro‐6‐methyluracil) sensitized by riboflavin. Indirect photolysis rate as a function of dissolved oxygen residual followed saturation curves. Methylene blue‐sensitized photolysis of bromacil reached maximum rate at 1 to 2 mg L−1 O2 and the maximum rate of riboflavin‐sensitized photolysis of terbacil was reached at approximately 5 mg L−1 O2. Dissolved oxygen uptake rates for the indirect photolysis reactions correlated with electrophilic attack of singlet oxygen on the substrates. Aeration requirements for indirect photolysis treatment systems may be calculated based on the criteria presented.
Streamflow Nutrient Dynamics on Coastal Plain Watersheds
Authors: Lowrance Richard , Leonard Ralph A.
Published: July 2010

Streamflow and water quality parameters were measured on five watersheds (262 ha‐11 487 ha) of the Little River in the coastal plain near Tifton, GA. Concentrations of nitrate, ammonium, chloride, ortho‐P, total P, total N, and electrical conductivity were determined. Loads and flow‐weighted concentrations were calculated for the five watersheds and for six subwatersheds formed by subtraction of smaller watersheds from larger ones. Mean concentrations and total loads calculated from samples taken every 3 h were not significantly different from samples taken every 12 h on two watersheds. In general, nitrate was enriched and chloride diluted relative to baseflow during storm events. This was attributed to reduction of nitrate in soils and aquifers of riparian areas. Both nitrate loads and concentrations were decreased during low flow years, whereas chloride concentrations were significantly higher in a year with abnormally low flows. Ortho‐P concentrations increased during storm events, but total P showed the opposite response. Enrichment of NO3‐N and ortho‐P and dilution of Cl and conductivity were due, in part, to concentrations in rainfall. Nutrient loads on the 11 watersheds and subwatersheds were similar except for one subwatershed that had the lowest percent of cropland but the highest loads. These high loads were due to exceptionally high flow rates in 1983 and 1984 following clear cutting of forest on nearly 25% of the subwatershed in late 1982. Nutrient loads in Streamflow were not correlated with the percent of land in spring‐planted row crops but were correlated with land in winter wheat, which is fertilized in late fall or early winter. Conditions that change hydrologic responses of watersheds may change the nonpoint sources of nutrients by changing water volumes and by altering processes that create nutrient concentrations in Streamflow.
Phosphate Uptake by Microbial Assemblages: Model Requirements and Evaluation of Experimental Methods
Authors: Tarapchak Stephen J. , Herche Lynn R.
Published: July 2010

A “compound” Michaelis‐Menten model provides a conceptual framework for analyzing substrate‐dependent phosphate (P) uptake by natural microbial assemblages. Phosphate uptake can be separated into three substrate domains: a region near ambient P concentrations, an intermediate region, and a high‐substrate region representing substrate saturation of microbial uptake sites. Simulated P uptake for hypothetical microbial communities, ranging from non‐phosphorus‐limited to multiple‐nutrient‐limited communities, shows that (i) commonly used “high‐level” P addition schemes will underestimate community uptake rates near natural ambient P concentrations in phosphorus‐stressed systems by at least an order of magnitude, and (ii) deviations from the simple Michaelis‐Menten model may be widespread in nature, particularly in highly phosphorus‐stressed or multiple‐nutrient‐limited systems. A P uptake experiment on a natural microbial assemblage from a phosphorus‐limited oligotrophic lake illustrates application of the compound model and statistical procedures for analyzing data. An empirical procedure, based on the concept of substrate‐dependent continuity in P uptake, is proposed to determine if P addition schemes are adequate to estimate uptake constants near ambient lakewater P concentrations.
Pitch × Loblolly Pine Growth in Organically Amended Mine Soils
Authors: Moss S. A. , Burger J. A. , Daniels W. L.
Published: July 2010

Soils on the mountainous terrain of southwestern Virginia are difficult to recover and replace before and after surface mining for coal. For this reason, combinations of soil, weathered rock, and blasted, unweathered rock are authorized as topsoil substitutes. If treated and amended properly, topsoil substitutes might be made even more productive for tree growth than the original soil disturbed by mining. Accordingly, the benefits of added municipal sewage sludge, sawdust, and inorganic fertilizer were assessed. Seven surface treatments were applied to 2:1 sandstone/siltstone overburden on a reclaimed coal surface mine in Wise County Virginia: fertilizer (168, 147, and 139 kg/ha of N, P, and K, respectively); limed (7.8 Mg/ha), and fertilized topsoil (30 cm deep); fertilized sawdust (112 Mg/ha) + 336 kg/ha slow‐release N (SRN); and lime‐treated municipal sewage sludge at rates of 22, 56, 112, and 224 Mg/ha. Stem volumes of 3‐yr‐old pitch × loblolly pines (Pinus rigida Mill. × P. taeda L.) were five times larger in soils amended with sawdust + SRN and nearly three times larger in soils amended with 22 and 56 Mg/ha sludge than fertilized‐only seedlings. Soil moisture retention was two times higher in sawdust‐amended soils than in all other treatments and contributed to increased seedling growth. Increased seedling mortality and decreased growth due to severe Mn deficiencies and/or high soluble salt levels was observed in the 112 and 224 Mg/ha sludge treatments.
Acid Precipitation Effects on Growth and Yield Responses of Twenty Soybean and Twelve Snap Bean Cultivars
Authors: Reddy M. R.
Published: July 2010

Greenhouse studies were conducted to determine the effects of simulated acid precipitation on growth, yield, and nutrient content of soybean [Glycine max (L.) Merr.] and snap bean (Phaseolus vulgaris L.). Twenty cultivars of soybean and twelve cultivars of snap bean were grown in pots and treated with simulated precipitation at pH 2.5, 3.5, 4.5, or 5.6 (control). Soybean and snap bean plants were treated with simulated precipitation once a week beginning until fruit maturity. Soybean plants showed leaf scorching and yellowing of leaves at pH 2.5 and 3.5, whereas snap bean did not show any visible symptoms. Soybean and snap bean cultivars responded differently to acid precipitation treatments. ‘McNair 700’ and ‘Pioneer 5482’ soybean and ‘Commodore’ bush and ‘Provider’ bush snap bean cultivars yields were decreased significantly under acid treatments. Eighteen soybean and 10 snap bean cultivars were unaffected. In general, acid precipitation treatments resulted in a greater number of soybean pods without seed compared to the control. Treatments at pH 3.5 and 2.5 affected soybean and snap bean growth and yield more than the other pH levels. Potassium content of soybean shoot decreased significantly under acid precipitation treatments, whereas Ca, Mg, and micronutrient contents were not affected by low pH treatment. Nutrient content of snap bean was unaffected by acidity.
Delivery of Nonpoint‐Source Phosphorus from Cultivated Mucklands to Lake Ontario
Authors: Longabucco Patricia , Rafferty Michael R.
Published: July 2010

Cultivated mucklands (Histosols) in western New York State were investigated as a nonpoint source of P to Lake Ontario. The 70 500‐ha Oak Orchard Creek watershed, which contains 3250 ha of heavily fertilized muck cropland, was monitored at several sites for a year in order to construct a P budget for the system and determine the mucklands' relative contribution. Runoff during the late winter‐early spring period appears to be the most important hydrologic factor in governing annual phosphorus loading from the mucklands, greater than either total precipitation or total runoff for the year. Surplus P leached from muckland soils and delivered to the creek in subsurface runoff accounts for the large dissolved P load measured in the creek at the study site draining the muck cropland. At this stream monitoring location, the mucklands represented only 27% of the drainage area, but were estimated to contribute between 55 and 86% of the annual dissolved reactive P (DRP) load. The load from Oak Orchard Creek to Lake Ontario for the study period was 37 000 kg of total P (TP), 20 000 kg of which was DRP. Half of the P load was delivered to Lake Ontario in 3 months—March, April, and May—when rain and snowmelt produced significant runoff and high creek flows. A mass balance calculation suggests that as much as 72% of the DRP load and 39% of the TP load entering Lake Ontario from Oak Orchard Creek could be attributed to P losses from the cultivated mucklands located 65 km upstream.