bluuebunny/crossref_metadata_2025 huggingface dataset:
Sediment Fractionation of Cu, Ni, Zn, Cr, Mn, and Fe in One Experimental and Three Natural Marshes
Authors: Lindau C. W. , Hossner L. R.
Published: July 2010

Dredged sediments from the Gulf Intracoastal Waterway near Galveston, Tex., were used as a substrate material in the construction of an experimental intertidal salt marsh. The objective of this research was to compare selected substrate properties of the experimental site with those of established marshes. Clay mineralogical properties of the experimental marsh were compared with those of three nearby natural marshes. A sequential chemical extraction procedure was used to obtain data on the partitioning of micronutrients and heavy metals among selected marsh substrate fractions.

Clay minerals found in the sediments of the experimental marsh were equivalent to those identified in the natural marshes. Total elemental substrate concentrations of Cu, Ni, Cr, Zn, Mn, and Fe averaged 7.9, 8.6, 25.5, 25.2, 123, and 12,200 µg/g, respectively, over the four marsh sites. Copper, nickel, zinc, and chromium displayed only minor variations in substrate partitioning between the experimental and natural marsh samples. Micronutrients and heavy metal concentrations in the exchangeable and water‐soluble fraction were low compared with other fractions. Approximately 30% of the total substrate Cu, Ni, and Zn was associated with the organic matter fraction. Metals fixed within the lattice structures of clay and silicate minerals ranged from 20% Mn for experimental marsh samples to 90% Cr for one of the natural marshes. Major differences in Mn and Fe substrate partitioning were observed when the experimental marsh samples were compared with those of the natural marshes.
Comparison of the Soil Water Cycle in Clear‐Cut and Forested Sites
Authors: Kachanoski R. G. , de Jong E.
Published: July 2010

A study was undertaken to determine the importance of subsurface flow and drainage in a northern Saskatchewan forested basin, and to examine the effect of clear‐cutting on the hydrologic cycle. Components of the soil water cycle were estimated for clear‐cut and forested sites during the spring melt and growing season. Surface runoff was measured using interceptor troughs and tipping‐bucket gauges. Soil water contents were measured using a neutron probe. Soil water fluxes were calculated using Darcy's Law and mass‐balance equations. Creek flow was monitored using a water‐level recorder and still well. Surface runoff was insignificant on all plots during the growing well. Surface runoff was insignificant on all plots during the growing season. Clear‐cutting increased hillslope water yield fivefold during the snowmelt period and doubled drainage during the growing season, compared with the forested site. Stream hydrographs indicated the basin was dominated by subsurface flow. This was consistent with measurement made on the forested plots where calculated drainage values could account for almost all observed streamflow. Hydrograph separation was carried out using mass‐balance calculations of Ca and Mg. The separation was used to identify sources of subsurface water contributing to streamflow.
Nitrate Depletion in a Second‐Order Mountain Stream
Authors: Swank Wayne T. , Caskey William H.
Published: July 2010

The amount of NO3‐N exported in a second‐order mountain stream draining a clearcut and logged mixed hardwood forest was studied over a 4‐year period. Calculations based on measurements of stream chemistry and discharge rates indicated a within‐stream depletion of NO3 from the upper reaches of the stream to the watershed outlet. Within‐stream depletion the first year of treatment was 127% of total NO3‐N discharged from the watershed outlet and declined in succeeding years after treatment to 99, 42, and 5%. Assays of the quantities of denitrifying enzymes in stream sediment samples suggested 1.7 kg N year−1 were lost via this pathway, compared with 3.9 kg N year−1 calculated from within‐stream depletion for the same time period. This study suggests sediment denitrification is a major pathway by which NO3‐N is lost. Within‐stream gaseous transformations are important when accounting for changes in N dynamics associated with forest management practices, and the measurement of only hydrologic discharge of NO3 could result in underestimation of N losses.
Heavy Metal Retention in Cattle Tissues From Ingestion of Sewage Sludge
Authors: Baxter John C. , Barry B. , Johnson D. E. , Kienholz E. W.
Published: July 2010

Cows and young steers were fed a diet containing 0 and 12% anaerobically digested Ft. Collins sewage sludge for 9 months, followed by a 4‐month withdrawal period during which no sludge was fed. Analyses of liver samples taken at intervals throughout the study showed that uptake of Cd, Cu, and Pb was linear with time. Cadmium increased from approximately 1 to about 20 ppm (dry wt) during the 9‐month sludge ingestion period. Lead and copper increased in liver tissues during the ingestion period; however, both decreased in a linear pattern after sludge was removed from the diet. There was no significant decrease of Cd levels in liver during the sludge withdrawal period. Zinc and iron levels in liver tissues were not affected by the sludge ingestion. Cadmium levels in kidney increased from approximately 5 ppm to approximately 55 ppm during the sludge ingestion period, with no significant decrease after sludge was removed from the diet. Lead and zinc concentrations in kidney increased during the sludge ingestion period, whereas Fe and Cu levels were not affected. Muscle tissues from cows and steers showed a slight, but significant, Cd increase during the sludge ingestion period. Cows showed no decrease in muscle Cd levels after the sludge withdrawal period, whereas muscle Cd concentrations of steers significantly decreased.

The amount of sludge consumed by cattle during the course of this study was extreme, and would not occur under normal agricultural practices; however, even though large quantities of sludge were consumed, there were no apparent ill effects on animal health or performance.
Dissipation of Massive Quantities of 2,4‐D and 2,4,5‐T n‐Butyl Esters in Field Mini‐Lysimeters
Authors: Majka Joseph T. , Cheng H. H. , Muzik T. J.
Published: July 2010

The patterns of dissipation of 2,4‐D (2,4‐dichlorophenoxyacetic acid) and 2,4,5‐T (2,4,5‐trichlorophenoxyacetic acid) n‐butyl esters, applied in 1:1 mixtures at 560 or 2,800 kg/ha of each herbicide to soils in field mini‐lysimeters, were monitored periodically from December 1976 to April 1979. The lysimeters were located in Pullman, Wash., and packed with soils from Washington, Wyoming, and Mississippi. Both 2,4‐D and 2,4,5‐T were dissipated to < 1% of the initial concentration at the lower application rate in the Washington and Wyoming soils; however, at the higher application rate, dissipation of 2,4‐D was greatly impeded and dissipation of 2,4,5‐T was negligible in these soils. Dissipation of both herbicides in the acidic Mississippi soil was extremely slow even at the lower application rate. Surface soil pH was lowered following herbicide application. Some downward movement of both herbicides from the 0‐ to 5‐cm to the 5‐ to 10‐cm soil layer was evident. By the end of the experimental period, revegetation had begun only on the Washington and Wyoming soils treated at the lower application rate.
Heavy Metal Absorption by Winter Wheat Following Termination of Cropland Sludge Applications
Authors: Chang A. C. , Page A. L. , Bingham F. T.
Published: July 2010

Winter wheat (Triticum spp. var. Anza) and soils were sampled at the third and the fourth year following the termination of sludge applications to a cropland site to examine the effect of deposited Cd and Zn on crop yield and metal concentrations in plants and the soil. Higher yields of wheat grain, due apparently to the residual N, P, micronutrients, and organic matter from the sludge treatment, were obtained from the sludge‐treated soils than from the controls. Although the treated soils received substantial quantities of Cu, Ni, and Pb, elevated plant‐tissue concentrations of these elements were not found in the wheat grain and straw. The plants, however, extracted greater amounts of Cd and Zn from the sludged than from non‐sludged fields. The metal contents of sludge‐affected wheat straw (0.07–0.16 µg/g Cd; 19–26 µg/g Zn) and grain (0.04–0.09 µg/g Cd; 22–45 µg/g Zn) were within the range typical for wheat grown on uncontaminated soils. Four years after the termination of sludge disposal, the heavy metals accumulated almost entirely in the 0‐ to 15‐cm soil layer where sludges were incorporated. The elevation of Cd and Zn did not result in any detectable increase in the concentration of water‐extractable Cd and Zn in the sludge treated soils. Attempts to recover heavy metals in the soil failed to account completely for all of the added metals. An average of 67% of the added metals was recovered from the surface 30 cm of the soil profile.
Survival and Growth of Pine Hybrid Seedlings With Pisolithus Ectomycorrhizae on Coal Spoils in Alabama and Tennessee
Authors: Berry C. R.
Published: July 2010

Container‐grown seedlings of specific pitch pine (Pinus rigida Mill.), loblolly pine (P. taeda L.), and pitch × loblolly pine (Pinus rigitaeda) hybrids were grown for 2½ years on unamended coal spoils in Alabama and Tennessee with Pisolithus tinctorius (Pt) ectomycorrhizae and, in separate plots, with naturally occurring ectomycorrhizae. The hybrid lines grew as well as or better than the loblolly or pitch lines. Seedlings with Pt ectomycorrhizae grew faster than seedlings with naturally occurring ectomycorrhizae. There was a significant genotype × mycorrhizal interaction at the Tennessee site. Trees with Pt ectomycorrhizae usually had lower concentrations of several elements in the foliage, including potentially toxic Mn, than trees with naturally occurring ectomycorrhizae. These data suggest that, on coal spoils, maximum benefit from Pt ectomycorrhizae can be obtained through selection of host genotypes known to be suited to the area and known to respond in a high degree to stimulation by the ectomycorrhizal fungus.
Uptake, Accumulation, and Translocation of Arsenical Compounds by Cotton
Authors: Marcus‐Wyner Lynn , Rains D. W.
Published: July 2010

Uptake, accumulation, and translocation of arsenic from different arsenical compounds were investigated in cotton plants (Gossypium hirsutum L. ‘SJ‐4’). Cotton plants grown in solution culture were exposed to arsenic trioxide (As2O3) from 0 to 8 µg As mL−1. Arsenic was readily taken up by the roots but was not translocated to the shoots. In contrast, when cacodylic acid (hydroxydimethylarsine oxide; (CH3)2As(O)OH) was applied in the range of 0–40 µg As mL−1, As was found not only in the roots but also in the leaves and reproductive structures. Plants treated with the herbicides MSMA (monosodium methanearsonate) and DSMA (disodium methanearsonate) also accumulated As in the roots and shoots. The defoliant, cacodylic acid, was applied as a foliar spray at the commercially recommendated rate of 1.4 kg/ha of cacodylic acid equivalents to cotton plants with green and mature bolls. Cottonseed from the treated bolls did not accumulae As above 2.6 µg As g−1, the tolerance limit. However, at higher application rates, the As concentrations increased in the cottonseed.

Cotton plants grown in the greenhouse in Yolo clay loam (fine silty, mixed, nonacidic, thermic Typic Xerorthents) with a soil background level of 6 µg As g−1, were grown with cotton‐gin trash containing cacodylic acid at 0 to 53.5 µg As g−1 mixed into the soil. Analyzed plant samples contained < 0.05 µg As g−1 and did not accumulate or concentrate arsenic from the soil.
Determination of Algal‐available Phosphorus on Soil and Sediment: A Review and Analysis
Authors: Hegemann David A. , Johnson Arthur H. , Keenan John D.
Published: July 2010

Important advances have been made recently in identifying the sources of algal‐available P in soils and sediments. Algal bioassays have shown that considerable amounts of the total soil P may be algal‐available under the appropriate environmental conditions. At present, however, the reported research contains no convincing evidence that the bioassay techniques used quantitatively measured all of the algal‐available P present in the soils and sediments tested,. Although chemical fractionation procedures have shown from which fractions algae obtain P, there is no evidence that all of the chemically extracted P in those fractions is algal‐available. Quantitative assessment of algal‐available P in soils and sediments will depend upou the development of long‐term algal assay procedures.
Distribution of Cadmium, Zinc, Copper, and Lead in Soils of Industrial Northwestern Indiana
Authors: Miller W. P. , Mc Fee W. W.
Published: July 2010

Five undisturbed locations of sandy Oakville and Plainfield soils under oak forest in the heavily industrialized region of northwestern Indiana were sampled at four depths, to assess the nature and extent of Cd, Zn, Cu, and Pb contamination. The litter layer and top 2.5 cm of soil at a site within 5 km of the center of the industrial complex were highly contaminated with Cd, Zn, Cu, and Pb. Levels of Cd and Zn decreased rapidly with distance to the south and east, while Cu and Pb decreased more erratically, with all metals reaching nearly background levels at 18 km. Samples taken deeper in the profiles (30 to 36 cm) did not show elevated metal levels compared with a rural site 67 km to the south. Sequential extraction methods applied to the top 2.5‐cm soil samples showed large amounts of relatively labile metals associated with exchange sites (KNO3‐extractable: 23, 10, 1, and 8% of total Cd, Zn, Cu, and Pb, respectively), bound by soil organic matter (Na4P2O7‐extractable: 21, 33, 24, and 41% of the total Cd, Zn, Cu, and Pb), and associated with carbonates and/or noncrystalline Fe oxides (EDTA‐extractable: 12, 8, 26, and 28% of the total Cd, Zn, Cu, and Pb). Minimal amounts of the metals were within the small amount of crystalline Fe and Mn oxides present in these soils. Non‐extractable (residual) metals amounted to 26, 32, 23, and 4% of the total Cd, Zn, Cu, and Pb.
Some Heavy Metals in Soils Treated With Sewage Sludge, Their Effects on Yield, and Their Uptake by Plants
Authors: Valdares J. M. A. S. , Gal M. , Mingelgrin U. , Page A. L.
Published: July 2010

The possible use of sludge with high heavy metal concentrations and at high rates in calcareous soil was demonstrated in this study. Mixtures of two sludges were added to soils in various proportions up to 4% sludge content. One sludge was rich in Ni and Cd, while the other was relatively poor in heavy metals. Three soils varying in pH from 7.7 to 5.5 were tested. The concentrations of Cd, Ni, Cu and Zn in the DTPA and saturation extracts of the soil‐sludge mixtures were determined and correlated with their uptake by plants and the yield of Swiss chard (Beta vulgaris L., cv. Ford Hook Giant) grown on these mixtures. The metal‐poor sludge hardly affected the yield of the relatively salt‐resistant Swiss chard. The metal‐rich sludge reduced the yield drastically in noncalcareous soils after a critical amount of that sludge (1.5%) was added to the soils. Yet, even 4% of this metal‐rich sludge increased the yield of Swiss chard, as compared with the sludge‐free control in a calcareous soil.

The best fit to yield was obtained by multiple regression with metal content in the soil saturation extract. The solubility in soil solution of Cd, Ni and Zn was strongly affected by the pH. The uptake of Ni and Zn by plants was significantly larger in the acid soil than in the calcareous soil. The difference in the uptake of Cd and Cu between the soils was smaller. Plant uptake of the metals was generally predicted better by the total metal addition or concentration in the DTPA extract than by metal concentration in the soil saturation extract. In noncalcareous soils the total metal addition correlated as well as metal content in the DTPA extracts with the metal concentration in the soil solution, with the uptake by plants and with the yield.

It has been known for some time that heavy metals introduced as mineral salts do not exhibit in soil the same behavior as heavy metals released from the sludge itself. The heavy metal contents in the soils were varied, therefore, by mixing the two sludges rather than by adding mineral salts to one sludge. Results of the relatively recent studies in which spiked sludges were used should be interpreted with care.
Effects of Ozone and Sulfur Dioxide on Tuber Yield and Quality of Potatoes
Authors: Foster K. W. , Timm H. , Labanauskas C. K. , Oshima R. J.
Published: July 2010

Air pollution injury of the potato plant (Solanum tuberosum L.) has been documented previously, but potato yield losses have not been estimated in replicated experiments having controlled exposures to ozone (O3) and sulfur dioxide (SO2) A controlled‐environment study involving the speckle‐leaf‐sensitive cultivar ‘Centennial Russet’ was conducted to examine the effects of chronic exposure to O3 and SO2 on plant growth and tuber yield and quality.

Ozone, at the highest seasonal dose (44.2 ppm‐h), reduced leaf dry weight 48%, root dry weight 58%, tuber number 38%, and total tuber yield 45%. Lower exposures affected these parameters in linear proportion to the O3 dose. Mean stem (minus leaves) dry weight, tuber dry weight, tuber dry matter percentage, partitioning of dry matter to tubers, and tuber sugar concentrations were not affected. Tuber N concentration increased linearly by up to 21% as the O3 dose increased. Plants grown outside of chambers in ambient air showed effects consistent with results obtained within the chambers. The plants grown outside received a total seasonal O3 dose of 50.4 ppm‐h and produced 58% less tuber yield than filtered air control plants.

Plant responses to SO2 exposure were much less pronounced than their responses to exposure to O3. However, leaf symptom development in O3‐treated plants was markedly intensified by the presence of SO2. Small reductions in tuber yield and mean tuber size, but not in tuber number, were observed in SO2‐treated plants. Tuber N concentration increased slightly in SO2‐treated plants.

A significant O3 × SO2 interaction was observed in the case of tuber N concentration only; SO2 accentuated the O3‐induced increase in N content.
Small Mammal Soil Burrowing as a Radionuclide Transport Vector at a Radioactive Waste Disposal Area in Southeastern Idaho
Authors: Arthur W. John , Markham O. Doyle
Published: July 2010

During 1978 and 1979, small mammals excavated a total mass of 12,450 kg soil to the 36‐ha surface of a solid radioactive waste disposal area in southeastern Idaho. Elevated concentrations of 238Pu, 239,240Pu, and 241Am were detected in excavated and surface soils in the waste disposal area. The inventory of 66 µCi (90Sr, 137Cs, 238Pu, 239,240Pu, and 241Am) transported to the surface of the waste disposal area by small mammal excavations was significantly (P ≤0.05) greater than the 20 µCi estimated to occur in excavated soils at a control area where no radioactive waste was disposed. Seventy‐seven percent of the radioactivity in soil excavated to the surface of the waste disposal area by small mammals was 238Pu, 239,240Pu and 241Am; 98% of the radioactivity in excavated soil in the control area was 90Sr and 137Cs. Small mammal burrowing is a mode of transuranic radionuclide transport to the surface of the waste disposal area; however, the total amount of plutonium in excavated soils was only 0.05% of the amount estimated to occur in waste disposal area surface soils in 1974.
Decomposition of Sewage Sludge Compost in Soil: IV. Effect of Indigenous Salinity
Authors: Tester C. F. , Parr J. F.
Published: July 2010

To determine the effects of indigenous salinity on rates of compost decomposition and nitrogen transformations, a sewage sludge‐woodchip compost was leached with water. Leached and unleached composts were mixed with a loamy sand at rates of 0, 112, and 224 t ha−1 (dry wt), equivalent to 5 and 10% of the dry soil weight, and incubated at 25°C in a constant atmosphere of CO2‐ and NH3‐free air for 160 d. Rates of compost C decomposition and N mineralization were determined by monitoring an air stream for CO2 and NH3 evolution, and by measuring changes in the extractable organic and inorganic fractions of C and N in soil with time.

The initial rate of CO2 evolution from the soil amended with leached compost lagged behind that of the soil amended with unleached compost. However, after 33 d of incubation, the leached compost treatments mineralized C at a faster rate, and after 160 d had evolved 14 and 32% more CO2 for the 112 and 224 t ha−1 rates, respectively. The initial lag may have resulted from partial removal of the more readily decomposable water‐soluble C by leaching. The total cumulative compost C evolved as CO2 from the unleached and leached compost mixtures after 160 d of incubation were about the same, i.e, 14% and 16%, respectively. However, the amounts of net N mineralized in the unleached and leached systems were greatly different. Approximately 14% of the N in the unleached compost had mineralized after 160 d, whereas the soil amended with leached compost exhibited a net immobilization of mineral N. These results indicate that salts and other compounds that are present in sewage sludge compost (water soluble) can inhibit compost decomposition when added to soil, and enhanced decomposition results in more immobilization of mineral N when these inhibitory compounds are removed by leaching.
Mineralization of Nitrogen in Sewage Sludges
Authors: Parker Chris F. , Sommers Lee E.
Published: July 2010

Mineralization of organic N is one of the principle factors governing the annual amount of sewage sludge applied to agricultural cropland. The mineralization of sludge organic N was studied in a Fincastle silt loam soil treated with 24 sewage sludges obtained from sewage treatment plants in several regions of the United States. The mineralization of sludge organic N was determined during a 16‐week incubation by analysis of inorganic N in (i) leachates from soil‐sludge‐sand mixtures and (ii) subsamples of unleached soil‐sludge mixtures. The nonleached procedure gave slightly higher estimates of mineralizable N in most sludges (average of 17 and 16% N mineralized by nonleached and leached procedures, respectively). The approximate amounts of mineralizable N in sludges expressed as a percentage of organic N were: raw and primary, 25%; waste‐activated, 40%; anaerobically digested, 15%; and composted, 8%. Inorganic N released from sludges by autoclaving in 0.01M CaCl2 or extracting with H2SO4 + KMnO4 was not highly correlated with N mineralization. Sludge organic N content was a reasonable predictor of mineralization of sludge N added to soils. The following regression equation was found to describe the mineralization of sludge organic N in soil: % of added sludge N mineralized = 6.37 × % sludge organic N + 4.63 (r = 0.77). To calculate the appropriate sludge application rates for agronomic crops, the percentage of sludge N mineralized during the initial cropping season should be related either to the process used for sludge treatment or to the concentration of organic N in the sludge.
Behavior of Chromium in Soils: V. Fate of Organically Complexed Cr(III) Added to Soil
Authors: James Bruce R. , Bartlett Richmond J.
Published: July 2010

Organically complexed Cr(III) added to soils may remain soluble, whereas the free Cr(III) metal ion would quickly become adsorbed and/or hydrolyzed and precipitated in the absence of soluble, complexing ligands. To separate these two phenomena, a laboratory procedure was developed to simulate the disposal of Cr(III)‐containing organic wastes in soils, and to investigate the solubilities of organic complexes of this heavy metal after addition to soil. The method involves adding Cr(NO3)3 to solutions of organic ligands adjusted to a pH between 3 and 8 to form inorganic hydrolyzed species and organic complexes at each pH. After measuring soluble Cr vs. pH, moist soil is added to bring the pH of each Cr‐ligand system to 6.5–7.0, thereby precipitating nncomplexed, inorganic Cr(III), and labile Cr(III)‐organic complexes. Subtracting Cr(VI) formed from total soluble Cr in the soil suspension gives a relative measure of organically complexed Cr(III) originally present in the aqueous systems at each pH.

Citric acid, diethylenetriaminepentaacetic acid (DTPA), fulvic acids, and water‐soluble organic matter from air‐dried soil kept Cr(III) in solution above pH 5.5, and prevented its immediate removal by soil.

Added Cr‐citrate remained soluble for at least 1 y in limed samples of an Ultic Hapludalf Ap horizon incubated at field capacity moisture. Because organic acids similar to those studied here may be found in sewage sludge, animal manures, and industrial wastewater, these results should be useful in predicting the fate of Cr(III) added to soils amended with such wastes.
Assessment of Heavy Metal Equilibria in Sewage Sludge‐Treated Soil
Authors: Behel David , Nelson Darrell W. , Sommers Lee E.
Published: July 2010

The objective of this research was to determine the effects of sewage sludge on speciation of metals in the soil solution. Sewage sludge was applied to an acid soil (pH ≈ 5) as a single treatment in 1971, or as annual treatments from 1971 through 1974 in amounts totaling from 50 to 800 t/ha. Surface soil samples were obtained from the plots in 1977 and the soil solutions were analyzed for Zn, Cd, Cu, Ni, Pb, Mn, Fe, Ca, Mg, Al, Na, K, PO4, SO4, Cl, pH, and organic C. The metal and ligand species in the soil solutions were calculated with the computer program GEOCHEM. Application of sludge increased soil solution concentrations of Zn, Mn, and Cd, while Cu, Ni, and Pb were present in most solutions at levels below the detection limits of the analytical methods used. Cadmium, zinc, and manganese in the soil solution appeared to exist predominately as the free ion. Complexation by inorganic and organic ligands ranged from 9 to 37%, 3 to 22%, and 3 to 31% of the total soluble Cd, Zn, and Mn, respectively, depending on the model used to represent metal interaction with soluble organic C. Cadmium was complexed with organic ligands to a greater extent than were zinc or manganese. Sulfate, phosphate, and chloride formed inorganic complexes with Cd, Zn, and Mn, but they constituted < 10% of the total metal present. Speciation of Zn and Cd into free metal ion and complexed forms was essentially the same in the soil solution, regardless of metal concentrations in solution and rate or frequency of sludge application. The solubility and DTPA extractability of Cd were increased to a greater extent by a single application of sludge than by multiple, annual additions.
The Effect of Soil Redox Potential and pH on the Reduction and Production of Nitrous Oxide
Authors: Smith C. J. , Wright M. F. , Patrick W. H.
Published: July 2010

Experiments were conducted in controlled redox systems to assess the effects of pH and Eh on N2O reduction and production. Soil/water suspensions (ratio 1:3) were incubated at pH 5, 6, 7 and 8.5, and the redox potential (Eh) was controlled at selected potentials between −200 and +350 mV. Maximum N2O reduction was measured at pH 6 and 7. The critical Eh for N2O reduction and production occurred at +250 mV for pH 6, 7, and 8.5, and +300 mV for pH 5. Although N2O reduction began at a higher potential at pH 5, the rate of reduction was slightly lower under anoxic conditions at this pH. Alkaline conditions did not change the critical redox potential, but the rate of N2O reduction was lower. The data also demonstrate that soil can act as a sink for N2O under anoxic conditions.
Proxy Variables from Pollution Control
Authors: Daines David R. , Heady Earl O.
Published: July 2010

Where the level of pollution from one farm cannot be reliably measured or estimated, environmental policies may be difficult to formulate and enforce. For this situation, a policy approach is suggested, which focuses on variables other than direct output of pollution. The use of proxy variables is illustrated in an analysis of alternative policies for controlling agricultural soil loss in the United States. An interregional programming model of U.S. agriculture is used to analyze and compare the proxy variable approach to direct limits and taxes on gross soil loss, with soil management practices employed as proxy variables. In achieving targeted soil loss reductions, the soil management practice policy would be less costly to society than a direct limit of 12.5 t/ha of soil loss, but a tax on each t of soil loss would be the least costly approach, assuming that soil loss could be easily quantified.
Hybrid Differences in Estimation of Preharvest Occurrence of Bright Greenish‐Yellow Fluorescence and Aflatoxin in Corn
Authors: Lillehoj E. B. , Manwiller A. , Whitaker T. B. , Zuber M. S.
Published: July 2010

Replicate, 200‐g kernel samples were acquired from 26 corn (Zea mays L.) hybrids of the 1980 South Carolina yield trials to study the interrelationships between moisture at harvest, bright greenish‐yellow (BGY) fluorescence, and aflatoxin concentrations. A modification of the BGY fluorescence detection method was developed to increase the accuracy of the rapid estimation of aflatoxin levels through a quantitative assessment of fluorescent material in finely ground samples. Ground samples from all of the test hybrids contained some BGY‐fluorescing particles, and > 90% of them contained aflatoxin. Although an elevated toxin level was only detected in kernels of a single hybrid, results based on the averages of hybrids in three hybrid maturity groups (short‐, mid‐, and full‐season) showed that kernels of the short‐season hybrids contained elevated levels of moisture, BGY fluorescence, and aflatoxin. Variation in moisture levels apparently was related to staggered planting dates of the three maturity groups to facilitate flowering at about the same time. Regression analyses showed significant associations between kernel moisture, BGY fluorescence, and aflatoxin. The results were considered in the context of development of rapid techniques for assessment of regional, preharvest aflatoxin contamination of corn.
Nitrogen‐15‐Labeled Nitrate Transport in a Soil with Fissured Shale Substratum
Authors: Rose C. W. , Chichester F. W. , Phillips I.
Published: July 2010

Published data on the fate of 15N‐labeled fertilizer applied to 4 Coshocton, Ohio, monolith lysimeters showed a series of declining NO3−‐N concentration maxima in the lysimeter percolate during 3 winter drainage periods subsequent to the single 336 kg/ha fertilizer application. A possible explanation of these concentration maxima as arising from the leaching of previously immobilized and subsequently mineralized N was quantitatively inadequate. In this study, we sought an alternative explanation of these observations.

The lowest meter in the 2.44‐m deep monolith profile of Keene silt loam consisted of fissured shale bedrock, and analysis of mass conservation of 15N‐labeled inorganic N in the fissured layer provided an explanation of these observed annually periodic concentration maxima. Some of the calculated flux of labeled N into the top of the fissured layer was shown to be stored within the layer, and to reappear in subsequent annual winter drainage periods. Two possible mechanisms, which allowed such temporary storage, were identified: storage within the pore space of the crack system, and storage in micropores of the weathered rock by lateral diffusion from solution contained in the cracks.
Atmospheric Sulfur Deposition, Neutralization, and Ion Leaching in Two Deciduous Forest Ecosystems
Authors: Richter D. D. , Johnson D. W. , Todd D. E.
Published: July 2010

In the 1981 water year, bulk precipitation was primarily a solution of dilute H2SO4, and SO42‐ was the dominant anion in tbroughfall and soil leachates in two eastern Tennessee deciduous forests. Ecosystem inputs of SO42‐, which included dry deposition of forest canopies, may have been up to 40% greater than input estimates based on atmospheric deposition sampling in open areas. Volume‐weighted mean annual pH of bulk precipitation was 4.3; of throughfall 4.8; and of leachates from O2, A1, and B21 soil horizons about 6.0. At both sites, strong acids in precipitation were largely neutralized prior to rainwater's infiltration into mineral soil.

Base cations that exchanged with H+ (hydrogen ions) in acid precipitation were almost entirely supplied by forest canopies and litter layers, and did not come directly from exchangeable mineral soil pools. Annual fluxes of HCO3− alkalinity from B21 horizons, about 0.42 and 0.51 kmol (−) ha−1 (keq ha−1) at the two sites, indicated that the natural H+ input from the partial ionization of H2CO3 was of similar magnitude to H+ input in bulk precipitation in 1981 [0.60 kmol(+)ha−1]. However, even in these infertile soils with low cation exchange capacities (CEC) [<7.2 cmol (NH4+) kg−1 (meq/100 g) in surface 50‐ or 80‐cm soil], exchangeable bases were more than two orders of magnitude greater than annual H+ input in bulk precipitation, and represented a substantial reserve for base cations in canopies and litter layers that exchanged with H+ in acid rain. Furthermore, inputs of H+ from acid precipitation were equal to about 0.4% of the base cations that are biologically cycling and immediately available in these ecosystems. Although poorly quantified, mineral weathering and deep rooting will supply, over time, substantial amounts of additional base cations for biologic cycling. Both soils are base‐poor Udults and classified as sensitive to acid rain, but the deposition, cycling, and soil data presented in this report indicate that leaching remains a process affecting cation reserves and soil development only over the very long term.
Nitrogen Loss From a High‐Fertility, Rotational Pasture Program
Authors: Owens L. B. , Van Keuren R. W. , Edwards W. M.
Published: July 2010

A beef cattle‐pasturing system involving four rotationally grazed summer pastures (SG) and four pastures used rotationally for winter grazing/feeding (WGF) was studied on sloping upland watersheds in Ohio to determine effects of livestock management on N levels in water. Both summer and winter areas annually received 224 kg N/ha as NH4NO3 fertilizer. Surface runoff was collected automatically during runoff events, and subsurface flow was sampled from spring developments on a weekly basis. Although seasonal N concentration and transport in surface runoff tended to be greater in the area occupied by the cattle, N concentration and transport in runoff from the two areas were quite similar and did not significantly impair water quality, based on U.S. Public Health Standards. The NO3‐N concentration in the subsurface flow from the WGF area was higher than in the subsurface flow from the SG area. The NO3‐N concentration in the subsurface flow from both areas increased progressively throughout the study period, and reached levels as high as 18 mg/L. The subsurface flow provided the main pathway for N transport, with the surface transport being approximately 20 and 14% of the total N transport from the SG and WGF areas, respectively. The amount of sediment‐N transported was very small because of low soil loss.
PCB Partitioning in Sediment‐Water Systems: The Effect of Sediment Concentration
Authors: Horzempa L. M. , Di Toro D. M.
Published: July 2010

The effect of sediment concentration variations on polychlorinated biphenyl (PCB) sorption to natural lake sediment (Saginaw Bay, Mich.) and montmorillonite clay has been investigated. In studies utilizing tritiated 2,4,5,2′,4′,5′‐hexachlorobiphenyl (HCBP), partition coefficient values for adsorption isotherms (πa) were found to increase as sediment concentrations (m) were decreased from m = 1000 mg/L to m = 50 mg/L. HCBP adsorption to montmorillonite (m = 1000 mg/L, πa = 2900 L/kg; m = 50 mg/L, πa = 10 600 L/kg) appeared to be more sensitive to sediment concentration than did adsorption to the Saginaw Bay sediment (m = 1000 mg/L, πa = 9900 L/kg; m = 50 mg/L, πa = 17 100 L/kg). Evidence suggests that these variations are not the result of nonlinear isotherms. Although variations in solution chemical composition and kinetic effects were found to affect partitioning, neither factor appeared to adequately account for the magnitude of the observed sediment concentration effect. In experiments in which sediment concentrations were decreased (m = 1000 mg/L to 10 mg/L) while equilibrium aqueous HCBP concentrations were maintained at approximately constant levels, πa values for adsorption increased. The behavior was in conformity with the isotherm results. The observed behavior might be due to direct solid phase interactions between suspended particles. The occurrence of such interactions in natural waters could have potentially significant implications for efforts to predict sediment‐water PCB distributions.
Loss of Fall‐Applied 2,4‐D in Spring Runoff from a Small Agricultural Watershed
Authors: Nicholaichuk W. , Grover R.
Published: July 2010

The loss of 2,4‐D (2,4‐dichlorophenoxyacetic acid) applied in fall to wheat (Triticum aestivum L.) stubble on fields of Wood Mountain loam soil in semiarid southwestern Saskatchewan was measured in surface runoff from snow. The range of runoff volumes over the 6‐y period was representative of runoff observed over a 30‐y period at the same location.

The loss of 2,4‐D was greater from the treated stubble compared with fallow, which served as the control. The average loss from the control of 1.3 g/ha gives an indication of background limits that can be expected if 2,4‐D is applied a year earlier.

The 2,4‐D loss in snowmelt runoff is similar to losses in rainfall runoff from a severe storm soon after application.

The 6‐y average loss was 4.1% of the amount applied (0.42 kg/ha). Correlation analysis showed the amount of loss to be a function of runoff.

The average flow‐weighted mean concentration of 31 µg/L was well below the USEPA maximum permissible level of 100 µg/L, and slightly above the U.S. National Academy of Sciences and National Academy of Engineering objective of 20 µg/L for drinking‐water standards.
Yield Reduction of Soybean Due to Exposure to Sulfur Dioxide and Nitrogen Dioxide in Combination
Authors: Amundson Robert G.
Published: July 2010

Two soybean [Glycine max (L.) Merr.] cultivars, ‘Beeson’ and ‘Hark,’ were grown in the field and exposed to SO2 alone and in combination with NO2 in open‐top chambers supplied with charcoal‐filtered air to remove ambient O3. The exposures were for 56 midday hours during the pod‐filling period at concentrations of approximately 481 or 1335 µg m−3 SO2 with or without 115 µg m−3 NO2.3 Visible injury was produced only on plants exposed to the higher SO2 concentration, but senescence was accelerated in several treatments (i.e., control about the same as low SO2 < low SO2 + NO2 < high SO2 < high SO2 + NO2. The treatments of high SO2 alone reduced the yields of Hark 26% and Beeson 9%; NO2 with high SO2 reduced the yields 35% for Hark and 31% for Beeson. The lower concentration of SO2 alone reduced the yields of Hark 20% and Beeson 6%; the presence of NO2 at the lower SO2 concentration did not increase the effect on yield reduction in either cultivar. These results suggest that (in the absence of ambient O3) NO2 in combination with SO2 can reduce soybean yield more if the SO2 dose is above a threshold value.
Sewage Sludge Application to Calcareous Strip‐Mine Spoil: II. Effect on Spoil and Corn Cadmium, Copper, Nickel, and Zinc
Authors: Pietz R. I. , Peterson J. R. , Hinesly T. D. , Ziegler E. L. , Redborg K. E. , Lue‐Hing C.
Published: July 2010

Metal concentrations in calcareous strip‐mine spoil and corn tissue (Zea mays L.) were examined in a long‐term field experiment using anaerobically digested sewage sludge. A total of 258 dry Mg ha−1 of sludge were applied to the highest sludge treatment from 1973 to 1977. Sewage sludge significantly increased the amounts of 0.1M HCl‐extractable Cd, Cu, Ni, and Zn in the spoil (0–15 cm). Spoil pH, 7.8, was not significantly affected by sludge applications, but yearly pH varied significantly.

Cadmium and zinc concentrations in leaves and grain were significantly increased each year by sludge applications. In 1977, 28.7 µg Cd g−1 and 200 µg Zn g−1 were observed in leaves from the highest sludge treatment. Grain Ni concentrations were significantly increased after application of 258 Mg ha−1 of sludge. Significant (P ≤0.01) increases were observed for the total plant uptake of Cd and Zn from 1974 to 1977 and Ni in 1977. The order of metal enrichment for corn was Cd > Zn > Ni > Cu.

Regression analyses showed that for Cd, Ni, and Zn the cumulative application in sludge and the 0.1M HCl‐extractable amounts from spoil were the most significant variables relating to the additive increases of these metals in corn tissue. The spoil mineral composition and pH appeared to be important in determining why Cd, Ni, and Zn availability did not decrease rapidly with time.
Performance of Goats and Lambs Fed Corn Silage Produced on Sludge‐Amended Soil
Authors: Dowdy R. H. , Bray B. J. , Goodrich R. D. , Marten G. C. , Pamp D. E. , Larson W. E.
Published: July 2010

An animal feeding study was conducted to measure the effects of feeding corn (Zea mays L.) silage grown on sludge‐amended vs. conventionally fertilized soil on the performance of dairy goats (Capra hircus) and market lambs (Ovis aries). Annual applications of 0, 15, 30, and 45 Mg/ha of sewage sludge (105–186 mg Cd/kg) produced corn silage that contained high levels of bioaccumulated Cd (5.26 mg/kg, year III). Zinc accumulated in the silage to a lesser extent, which resulted in undesirably low Zn/Cd ratios. In vitro digestible dry matter, cell wall constituents, acid detergent fiber and lignin, and silica accumulation were not affected by sludge fertilization.

Dry matter intake, daily milk production, and feed efficiency of dairy goats were not affected by 3 y of continuous consumption of high Cd silage. Market lambs fed sludge‐fertilized corn silage tended (P < 0.05, year II) to have higher daily gains than did those fed control silage, whereas feed efficiency (kilograms gain ÷ kilograms feed) was not affected by sludge fertilization.
Influence of Atrazine on Denitrification in Soil Columns
Authors: Cervelli S. , Rolston D. E.
Published: July 2010

The effects of the herbicide atrazine (2‐chloro‐4(ethylamino)‐6‐(iso‐propylamino)‐s‐triazine) on denitrification was evaluated during steady transport of 15N‐nitrate through 0.15 m long columns of San Cataldo silt loam (Fluvisol, according to the FAO world map legend) and Yolo loam soil (Typic Xerorthents). The soil atmosphere was maintained at a small O2 partial pressure by flowing a gas mixture of 70% He and 30% N2 through plastic jackets surrounding the plastic soil columns, which had many holes (1 mm diam) drilled through the column sides. This column design allowed evolved N2 and N2O gases to be measured in the effluent gas of each column. The nitrate (NO3−) concentration in the solution effluent and the evolved gases from columns with added atrazine (3 mg kg−1) were compared with that from columns without atrazine. Nitrate reduction rates were determined from a mathematical solution of transport and transformation of nitrate according to first‐order kinetics. The presence of atrazine in the soils resulted in slightly increased nitrate reduction rates over that of the controls. Atrazine caused a decrease in the N2/N2O ratio of the evolved gases. A small amount of NO was also detectable in San Cataldo column without atrazine. The apparent inhibition of N2O reduction by atrazine may have environmental implications in relation to N2O release from the soil to the atmosphere.
Determining Sludge Fertilization Rates for Forests from Nitrate‐N in Leachate and Groundwater
Authors: Brockway Dale G. , Urie Dean H.
Published: July 2010

Municipal and papermill wastewater sludges were applied to conifer and hardwood forests growing on sand soils (Entic Haplorthods, Spodic Udipsamments, and Alfic Haplorthods), in northwestern Lower Michigan where annual precipitation averages 765 mm/y, to investigate the impact of sludge on nitrate‐N concentrations in soil water and groundwater. During the first growing season after treatment, all forms of N in groundwater and soil water remained near background levels except under aspen (Populus grandidentata Michx.) plots treated with 46 dry Mg municipal sludge/ha. Following the first spring snowmelt period after sludge was applied (spring 1977), nitrate‐N concentrations exceeded the 10 mg/L potable water standard in groundwater under plots treated with 16 or more dry Mg/ha undigested papermill sludge. Soil leachate exceeded 10 mg/L under pine plantations receiving 19.3 dry Mg/ha and aspen sprout stands receiving 23 dry Mg/ha or more anaerobically digested municipal sludge.

Sludge application rates which would not degrade water quality in water‐table aquifers were estimated by regression analysis of nitrate (NO3−) concentrations in relation to dry solids loading. Applying raw papermill sludge at rates not exceeding 9.5 dry Mg/ha (670 kg total N/ha) to a red pine (Pinus resinosa Ait.) plantation was found to be consistent with levels that met the 10 mg/L potability standard in groundwater. These analyses showed anaerobically digested municipal sludge could be applied to a red pine and white pine (Pinus strobus L.) plantation at 16.5 dry Mg/ha (990 kg total N/ha) or less and to aspen sprouts at rates up to 19 dry Mg/ha (1140 kg total N/ha) with the same water quality limits.
A Comparative Study of Bermudagrass Grown on Soils Amended with Aerobic or Anaerobically Digested Sludge
Authors: Amundson R. G. , Jarrell W. M.
Published: July 2010

A greenhouse pot experiment was conducted in which bermudagrass [Cynodon dactylum (L.) Pers.] was grown on Holtville silty clay and San Emigdio fine sandy loam soils, which were amended with aerobically (AEDS) and anaerobically (ANDS) digesed sludges to supply N at 600, 900, and 1200 kg ha−1. Ammonium sulfate [(NH4)2SO4] was applied to other pots at rates to supply N at 300 and 600 kg ha−1. A second 600 kg N treatment as (NH4)2SO4 was applied in three split applications. All (NH4)2SO4 treatments received 60 kg of P as monocalcium phosphate (MCP). Cumulative yields of bermudagrass grown on aerobic sludge treatments were greater than those yields on anaerobic sludge treatments for both soils. Patterns of plant yields indicate that a large initial release of plant‐available N occurred in aerobic sludge treatments relative to anaerobic treatments. Though not statistically significant, more N was accumulated by plants grown on aerobic than on anaerobic sludge‐amended soils. On both soils, aerobic sludge‐P was more plant‐available than anaerobic sludge‐P. Calculated recoveries of sludge‐applied N and P showed little variation due to soil type at equal rates of sludge application. For both soils, 1 Mg of aerobic sludge or anaerobic sludge produced bermudagrass yields equivalent to those resulting from the application of 24–37 kg (NH4)2SO4‐N and 7–10 kg (NH4)2SO4‐N, respectively. Tissue concentrations of Cd were below 9 × 10−4 mmol kg−1 for all treatments, and were not considered to be excessive.