bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Soil Response to Acidic Deposition in Nonsulfate Adsorbing Soils
Authors: Bloom P. R. , Grigal D. F.
Published: July 2010

A simple semiempirical model for the prediction of changes in soil pH and base saturation with acidic deposition was developed. In steady‐state ecosystems acidic deposition results in losses of basic cations from exchange sites. In the model, depletion of exchangeable bases is calculated from the difference between input acidity and output of H+ and Al3+ in water percolating through the solum. A correction for the decrease in bicarbonate weathering is made but sulfate adsorption is not considered. Estimates including the effect of increased mineral weathering with decreased pH can be made if the natural weathering rate is known and if the order with respect to H+ is known for the rate expression for soil weathering. The model predicted laboratory data for the acidification of samples for three soil horizons. For a fourth horizon, that was formed in contact with bedrock and high in weatherable minerals, the model overestimated the effect of the acid. Model predictions using soil data showed a slow decrease in soil pH and base saturation until the pH region of Al buffering was attained and then a new steady‐state was achieved. The pH and base saturation in the Al buffering region was similar to that found in very acid soils under forest vegetation.
Plant Uptake of Cadmium from Acid‐extracted Anaerobically Digested Sewage Sludge
Authors: Logan Terry J. , Feltz Robert E.
Published: July 2010

Approximately 80% of the Cd in an anaerobically digested sewage sludge (initially containing 11.6 mmol Cd kg−1) was removed by acid extraction and dewatering. The acid extracted sludge was treated by (i) neutralization to pH 5.9 with Ca(OH)2, (ii) addition of monocalcium phosphate (MCP) followed by Ca(OH)2 neutralization to pH 5.9, and, (iii) addition of rock phosphate (RP) followed by Ca(OH)2 neutralization to pH 5.9. The three treated sludges and the non acid‐extracted sludge (aerated prior to application to soil) were applied to Spinks loamy sand (sandy, mixed, mesic, Psammentic Hapludalfs) at rates equivalent to 18.7 and 37.4 µmol Cd kg−1. Swiss chard (Beta vulgaris) was grown in the greenhouse for 56 d. Cadmium, Fe, Ca, and P were measured in saturation extracts of treated soil at 0, 4,18, 39, and 60 d after sludge addition. These data indicated that hydroxyapatite was stable throughout the study in the soil receiving MCP treated sludge but not in other soil treatments. Cadmium concentration in saturation extracts of the soil with MCP sludge decreased below the detection limit of 1.8 × 10−10 mol L−1 by day 4 at the 37.4 µmol Cd kg−1 application rate, while Cd concentrations in saturation extracts of the other sludge treatments were much higher throughout the study. Chard yields were higher in the control than in any of the sludge treatments, and the difference was attributed to greater N availability in the control. Cadmium concentration in Swiss chard tissue at harvest was significantly lower from the MCP sludge than from the other sludges. Cadmium concentration in chard tissue was also higher from the aerated sludge (11.9 mmol Cd kg−1) than from the three acid‐extracted sludges (2.58–3.29 mmol Cd kg−1). No significant difference in the Cd concentration of chard was obtained for the 18.7 and 37.4 µmol Cd kg−1 rates of the MCP sludge, while Cd concentrations in chard increased linearly with Cd applied by the other sludges.
Environmental Effects on Metsulfuron and Chlorsulfuron Bioactivity in Soil
Authors: Anderson R. L.
Published: July 2010

Metsulfuron {2‐[[[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐71)amino] carbonyl]amino]sulfonyl]benzoic acid}, a sulfonylurea herbicide, is persistent in soil and may injure susceptible crops. To elucidate potential carryover situations, the effect of environment and soil factors on metsulfuron bioactivity was examined in a Platner loam (fine, montmorillonitic, mesic, Aricidic Paleustolls) and a Valent sand (mixed, mesic Ustic Torripsamments) soil with a corn (Zea mays L.) root bioassay. Increasing soil temperature from 8 to 24°C in the loam soil reduced the duration of metsulfuron bioactivity by 49%. The temperature effect on metsulfuron bioactivity in the sand was less pronounced, as the 16°C increase resulted in only 20% reduction of duration of bioactivity. The effect of soil water content on metsulfuron bioactivity was soil and temperature related. Increasing soil water increased metsulfuron degradation in the sand at 24°C, but not at 16°C, while in the loam, metsulfuron degradation was not affected by soil water level at either temperature. Incorporating metsulfuron in soil reduced the duration of bioactivity, while the presence of growing wheat (Triticum aestivum L.) plants in metsuifuron‐treated soil did not affect the duration of bioactivity. Metsulfuron retained on surface straw residue was washed off by simulated rainfall, but duration of metsulfuron bioactivity was increased by this straw residue retention. Chlorsulfuron {2‐chloro‐N‐[[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl) amino]carbonyl]benzenesulfonamide}, another sulfonylurea herbicide, persisted slightly longer than metsulfuron at the same rate in both soils when incubated at 16°C with identical soil water levels.
Crop Response to Soil Applications of Phosphogypsum
Authors: Mays D. A. , Mortvedt J. J.
Published: July 2010

Phosphogypsum (PG), a by‐product of the phosphate industry, was incorporated with soil to determine effects of land disposal on crop growth and uptake of cadmium (Cd) and radium (Ra). Application rates of PG were 0, 22, and 112 Mg ha−1. Soil was cropped sequentially with corn (Zea mays L.), wheat (Triticum aestivum L.), and soybeans [Glycine max (L.) Merr.] over a 1–5‐yr period. Yields of corn were decreased at the high PG rate, apparently because of a physiological calcium‐magnesium (Ca‐Mg) imbalance, but yields of wheat and soybeans were not affected by PG application. Concentrations of nutrient elements and Cd in the grain of each crop were not affected by PG application; the Cd concentration of Pg was 0.23 mg kg−1. Radiological assay of grain samples showed no increase in 226Ra radioactivity in any of the three crops due to PG application; PG contained 925 Bq kg−1 (25 nCi kg−1) of radioactivity. Analyses of soil after soybean harvest showed that the level of radioactivity in the surface 15‐cm layer increased from 35 Bq kg−1 in the control treatment to 73 Bq kg−1 at the high PG rate; the radioactivity level in the subsurface layer was not affected. These results suggest that PG may be applied to agricultural soils at relatively high disposal rates without increasing levels of Cd or radioactivity in corn, wheat, or soybean grain. Applications of By‐product PG at recommended rates of 500 to 1000 kg ha−1 as a source of Ca or S for crops would result in lower levels of Cd and radioactivity than those reported here.
Effects of Fertilizer, Pig Manure, and Sewage Sludge on Timothy and Soils
Authors: Warman P. R.
Published: July 2010

Research determined the effect of fertilizer, sewage sludge and pig (Sus scrofa domesticus) manure on timothy (Phleum pratense L.) yield, tissue composition, and soil fertility from 1979 to 1982. Field plots in Quebec on sandy loam and clay loam soils compared 0 fertilizer and annual applications (1979–1981) of two rates of fertilizer (F1,F2 = 110‐50‐85, 220‐50‐85 kg ha−1 N‐P2O5‐K2O), pig manure (PM1,PM2 = 75 150 wet Mg ha−1) or aerobically digested sewage sludge (SS1,SS2 = 150 300 wet Mg ha−1). The F2, PM2, and SS2 amendments produced similar yields and plant uptake of nutrients all 3 yr. Although nutrient uptake by timothy was generally higher on the clay loam, due to higher soil fertility and less leaching losses, the percent recovery of the applied nutrients (excluding N and Mn) was similar at both sites. Based on the K:(Ca + Mg) content and regardless of the treatment applied, a potential grass tetany problem exists in the timothy grown in the clay loam. No metal contamination was found in the soil or timothy following the application of any amendment. Only four soil chemical properties, of 11 measured, were influenced by the treatments on either soil. The PM2 treatment increased NO−3‐N, Bray P2 and extractable K; the SS2 treatment increased Bray P2 and DTPA Cu. The author, therefore, recommends the application of any of these amendments to timothy at either of the two rates.
Reducing Aspergillus Species Infection of Peanut Seed Using Resistant Genotypes
Authors: Mixon A. C.
Published: July 2010

Studies were conducted to determine the potential of reducing aflatoxin contamination using recently released peanut (Arachis hypogaea L.) genotypes found to be resistant to seed invasion by aflatoxin‐producing strains of Aspergillus Link ex Fr. flavus and A. parasiticus Speare. Under certain environmental conditions these fungi metabolize aflatoxins which are highly potent carcinogens when ingested by animals. Resistant lines (GFA‐1, GFA‐2, AR‐1, AR‐2, AR‐3, and AR‐4) were evaluated for resistance to seed invasion and colonization of intact, dry seed by the Aspergillus species. When rehydrated and inoculated seed were incubated under favorable conditions, all the resistant peanut lines were more resistant than commercial peanut cultivars, “Florunner” and ‘Sunbelt Runner’, in successive years of evaluating. Pod yields of GFA‐1 and GFA‐2 pod yields approached those of the commercial cultivars. AH the resistant genotypes could reduce contamination of seed immediately following harvest or in short term storage when environmental conditions are conducive to A. flavus and A. parasiticus infection.
Potassium Losses in Runoff and Drainage Waters from Cropped, Large‐scale Lysimeters
Authors: Jones Robert L. , Hinesly Thomas D.
Published: July 2010

Losses of total recoverable potassium (K) were measured in runoff and percolate waters from field lysimeter plots of Blount silt loam (fine, illitic, mesic Aeric Ochraqualfs) from May 1972 through April 1974. Six plots were irrigated annually with digested sewage sludge, while another six plots which had been treated with a complete fertilizer were irrigated with well water. Each year all plots were fertilized with KCl in amounts that supplied 269 kg K ha−1 prior to the preparation of a seedbed for corn (Zea mays L.). For the 2 yr of record, combined K losses in runoff and drainage waters from sludge‐treated plots averaged 41.9 and 8.2 kg ha−1, respectively. For the same years, losses from plots irrigated with well water averaged 23.3 and 10.5 kg K ha−1 in runoff and drainage waters, respectively. The differences between treatments within each year were not significant, but they were significant between years within treatment. Large K losses occurred in runoff during heavy summer rains and in winter when rapid snow melt and rain events took place. Consistently higher K losses were observed in drainage waters during late winter and spring periods for both years. Median concentrations of total recoverable K in runoff and drainage waters from sludge‐treated plots were, respectively, 7.5 and 4.8 mg L−1 in the first year and 7.8 and 2.4 mg L−1 during the second year. Respective data for water‐irrigated lysimeters were 6.0 and 2.9 mg K L−1 in 1972 through 1973 and 7.5 and 1.8 mg K L−1 in 1973 through 1974. Potassium losses were small when compared to amounts supplied as constituents of sludge and fertilizer and to soil levels of total native and acid‐extractable K. In the drier year, 1973 through 1974, total K losses in runoff and drainage from plots receiving conventional fertilizers were similar to weights of K removed in grain.
Response of Soybean to Low Concentrations of Ozone: II. Effects on Growth, Biomass Allocation, and Flowering
Authors: Amundson Robert G. , Raba Richard M. , Schoettle Anna W. , Reich Peter B.
Published: July 2010

Soybean plants were subjected to ozone (O3) and water stress to determine whether the two stresses interact to alter growth. Potted soybean (Glycine max [L.] Merrill cv. Hodgson) plants were exposed to O3 for 6.8 h daily in four controlled environment chambers. The air supply to the chambers was filtered, and constant amounts of O3 were added: 0.01, 0.05, 0.09, or 0.13 µL L−1. Within each O3 treatment, half of the plants were watered daily and half had water withheld 2 or 3 d per week. At 2‐week intervals plants were harvested and divided into leaves, stems, and roots. Exposure to increasing concentrations of O3 resulted in a linear decline in growth, but did not influence the allocation of biomass to roots, stems, and leaves. Ozone also delayed the onset of flowering. Weekly water stress periods of 2 or 3 d duration significantly inhibited the growth of soybean but did not alter the allocation of biomass or delay the onset of flowering. Water stress acted to close stomates and reduce the effective O3 dose which resulted in a reduced percent reduction in growth that could be attributed to O3 stress.
Metals in Low‐elevation, Southern Appalachian Forest Floor and Soil
Authors: Berish C. W. , Ragsdale H. L.
Published: July 2010

Litter and humus, and surficial (0–5 cm) and deeper (25–30 cm) mineral soil were collected from two, 90‐yr‐old forests to measure readily‐available, potentially‐available, and total‐pool quantities of metals in low elevation, southern Appalachian soils. Soils of the two forested watersheds are either in the Evard or Tate series, a fine‐loamy, mesic family of Typic Hapludults. Concentrations of Ca, K, Mg, Mn, Cd, Co, Cu, Pb, and Zn in soils were determined by three extraction methods (water soluble, weak acid, and total dissolution). Total soil Ca, K, Mg, and Mn pools were two or more orders of magnitude greater than trace metal pools. Total soil metal pools at both depths followed a trend of K ≫ Ca ≥ Mg > Mn ≫ Zn > Cu ≫ Pb ≥ Co ≫ Cd. Fractions of the total metal pools that were readily and potentially available generally decreased with depth.

Litter and humus trace metal concentrations of two low elevation watersheds in the Coweeta Basin contain lower concentrations of Cu, Zn, and Pb than commonly reported for the northeastern USA. Aerial deposition of Cd, Co, and Pb was indicated by the surficial forest floor enrichment in those elements compared to the mineral soil. The largest trace metal pool in forest floor litter and humus was for lead, and was presumably from long‐range transport, deposition and subsequent retention on humic materials. Metals measurement in the relatively pristine organic forest floor and mineral soil at Coweeta will be useful for future evaluations of trace metal impacts on southern Appalachian forest ecosystems.
Analysis of Time‐dependent Chemical Processes in Soils
Authors: Skopp J.
Published: July 2010

Analysis of time‐dependent processes in soils has been the subject of recent interest. Examples of such interest include the demonstration of nonequilibrium conditions during transport, slow release of plant nutrients, and a fundamental interest in reaction mechanisms. No unified approach to these problems exists in the literature. The present study was undertaken to provide uniformity in terminology and a methodology for solving a variety of problems. The interrelationship of chemical kinetics and transport processes is examined. Particular attention is paid to potential ambiguities and alternative interpretations of concentration histories. A variety of rate law formulations are presented. Microscopic and macroscopic approaches to transport process are described. The implications of these descriptions of transport upon chemical reactions are discussed, it is concluded that reaction kinetics and transport may be readily confounded. Furthermore, different kinetic mechanisms may result in concentration histories that are not distinguishable experimentally.
Nitrogen Mineralization of Sewage Sludges in Soils
Authors: Garau M. A. , Felipó M. T. , de Villa M. C. Ruiz
Published: July 2010

In order to profit from recycling sewage sludge through the soil‐plant system, it is necessary to know the amount of mineralizable organic‐N from sludge. The purpose of this study was to determine N‐mineralization of two sewage sludges in two different soils, comparing leached and nonleached incubation procedures. The cumulative N mineralized during successive incubation periods increased linearly with incubation time and sludge incorporation rate. The mineralization process was more influenced by soil type than by rate and kind of sludge applied. The amount of mineralized‐N was higher for the leaching procedure. This cumulative‐N expressed as the percentage of applied organic‐N was inversely dependent on sewage sludge rate added for the leached procedure and is independent of the rate for the nonleached. The N‐mineralization rate was 0.0202 ± 0.0011 and 0.0650 ± 0.0068 d−1, respectively, for leached and nonleached procedures. The potentially mineralizable N increased with the sludge rate applied and was higher for aerobic sludge and neutral soil. In general, the leached method gave twofold higher vlaues than the nonleached method. The net percentage of potentially mineralizable N vs. organic‐N added was 43.0 ± 7.8 and 27.7 ± 4.0, respectively, for leached and nonleached procedures.
pH Buffering in Forest Soil Organic Horizons: Relevance to Acid Precipitation
Authors: James Bruce R. , Riha Susan J.
Published: July 2010

Samples of organic surface horizons (Oi, Oe, Oa) from New York State forest soils were equilibrated with 0 to 20 cmol HNO3 kg−1 soil in the laboratory by a batch technique designed to simulate reactions of acid precipitation with forest floors. Each organic horizon retained a constant percentage of added H+ (67–96%) regardless of quantity added, and buffer capacities of the samples ranged from 18 to 36 cmol (H+) kg−1 (pH unit)−1, an order of magnitude higher than those measured in underlying mineral horizons. Calcium was the dominant cation in unacidified equilibrium solutions, and its concentration changed the most in response to acidification of the soils. Aluminum contributed <1% to total cationic charge in solution and Fe concentration decreased upon addition of up to at least 5 cmol (H+) kg−1. From 38 to 79% of H+ removed by the soils was not balanced by increases in soluble Ca, Mg, K, Mn, Fe, Zn, Al, and Cu, and buffering by soluble organic and inorganic constituents accounted for 8 to 58% of H+ removal. Protonation of anions of weak organic acids in solution and solid phases probably accounted for this H+ removal without increasing cation concentrations. Because of H+ removal by forest floor organic horizons and the dominance of Ca in equilibrium solutions, potential impacts of acid precipitation on aluminum solubility of underlying mineral horizons of forest soils will be due more to Ca(NO3)2 and CaSO4 in leaching water, rather than to direct effects of HNO3 and H2SO4.
Chemical Quality of Suspended Sediment from Watersheds Subjected to Surface Coal Mining
Authors: Dick W. A. , Bonta J. V. , Haghiri F.
Published: July 2010

The chemical quality of suspended sediment in surface water runoff, which is changed as a result of surface coal mining activities, may influence water quality and have effects where the sediment is deposited downstream from the mine site. Suspended sediment samples were collected from three small watersheds in east‐central Ohio prior to, during, and after surface mining and reclamation. The chemical quality of the suspended sediment was determined by measuring Ca, Mg, Fe, Al, Mn, Ni, Pb, Cd, Cu, Zn, Sr, P (following pretreatment of the sample with 30% H2O2 and extraction with 0.3 MHCl), acetate‐soluble SO2−4, pH, organic C, and Hg. Differences in concentrations of parameters were observed among the three watersheds and were related to the composition of the overburden material. At Watersheds C06 and M09, the concentrations of the chemical parameters in suspended sediment samples, collected after reclamation had been completed, were not significantly (P = 0.05) different than concentrations measured prior to surface mining. An exception was the concentration of organic C, which was lower during the postreclamation period. The concentrations of Mg, Fe, and Al were significantly greater at Watershed J11 during the postreclamation period compared to the premine period while P, organic C, Mn, and Pb concentrations were significantly lower. Concentrations of parameters in suspended sediment samples collected concurrently at the inlet and outlet of the sediment ponds at Watersheds C06 and M09 were not significantly (P = 0.05) different. However, due to settling of the larger and heavier sediment particles, a trend toward increased concentration of parameters in sediment samples collected at the pond outlet compared to the pond inlet occurred at both Watersheds C06 and M09.
Effect of Sludge Additions on Nitrogen Removal in Soil Columns Flooded with Secondary Effluent
Authors: Lance J. C.
Published: July 2010

Mixing sewage sludge with the surface layer of soil in columns was tested as a way to increase N removal in soil columns flooded with secondary effluent containing 18 mg/L total N. Dry sludge was mixed in the top 5 cm of two columns at an application rate equivalent to 50 Mg/ha. The infiltration rates of the two columns were 30 and 60 cm/d. The infiltration rates were the same before and after addition of sludge. Nitrogen (total) removed by the 30 cm/d column was increased from about 22 to about 55% by adding sludge. The same amount of sludge added to the 60 cm/d column decreased N removal for several cycles before N removal stabilized at 34% or at about double the rate measured before sludge was added. Sludge decomposition in the soil columns apparently provided a steady source of organic C for denitrifying bacteria. Nitrogen removal at the 30 cm/d infiltration rate was sufficient to maintain the average total N content in the water from the column outlet at 8 mg/L. These results show that mixing sludge with soil in ground‐water recharge basins could allow increased application rates of sewage water and thereby reduced costs. Utilization of some sludge without contaminating the groundwater would be an added benefit.
Phosphorus Solubility in Sludge‐amended Calcareous Soils
Authors: O'Connor G. A. , Knudtsen K. L. , Connell G. A.
Published: July 2010

Sludge additions to calcareous soils in New Mexico increased water soluble and NaHCO3‐extractable P as well as plant uptake of P, whereas inorganic fertilizer P has often been ineffectual. This paper describes attempts to explain sludge effects in terms of increased solubility of secondary Ca‐P solid phases (e.g., tricalcium and octacalcium phosphate) in amended calcareous soils. Both greenhouse and field data, representing several croppings of amended soils were examined. Ancillary effects, primarily slight pH reductions, associated with sludge additions to the soils were apparently responsible for increased P solubility in amended soils.
Environmental Radiation Exposure Rate in Louisiana
Authors: Beck James N. , Keeley Dean F. , Meriwether John R. , Thompson Ronald H.
Published: July 2010

The environmental radiation exposure rate has been measured using thermolumineseent dosimetry at 26 monitoring stations in Louisiana over a period of 2 yr. Sets of LiF dosimeters that are essentially tissue equivalent in their energy response characteristics were left at each station for 90 d, replaced, and the exposure they received determined. The chips were exposed to a standard source three times during the 2‐yr period to assure their accuracy. On at least two occasions during the study period, samples of soil were taken at each station. These samples were dried, ground, sieved for uniformity, and analyzed by gamma ray spectroscopy. The specific activity of 40K, 137Cs, and some of the decay products of U and Th were determined. The average exposure rate for all stations was found to be 19.6 ± 2.8 µC kg−1 yr−1 (76 ± 11 mR yr−1). The range in values, from 15.0 to 25.5 µC kg−1 yr−1 is generally explained by the variation of the 40K specific activity in the natural soil bodies where the stations are located. The 40K specific activity ranges from 100 to 900 Bq kg−1 across the state. The other activities are also related to soil type, but none vary as dramatically as 40K. The results obtained agree with other more limited surveys and provide a large, reliable baseline to which future studies can be referred when assessing changes in environmental radiation levels.
Wood Residue and Fertilizer Amendment on Bentonite Mine Spoils: II. Plant Species Responses
Authors: Smith J. A. , De Puit E. J. , Schuman G. E.
Published: July 2010

Second growing season plant species biomass, composition, and diversity responses to varied wood residue and fertilization treatments on bentonite mine spoils are reported. Two seed mixtures, each with six plant species,, were seeded on four wood residue rates (0, 45, 90, and 135 Mg ha−1) and four N fertilization regimes (0, 2.5, 5.0, and 7.5 kg N Mg−1 of wood residue). Some species were poorly established irrespective of treatment (green needlegrass, Stipa viridula) or became established to a limited extent only under specific residue‐fertilization treatment combinations (slender, crested, and pubescent wheatgrass; Agropyron trachycaulum, A. desertorum, and A. trichophorum, respectively). The remaining species became well established under specific treatment combinations. Western wheatgrass (Agropyron smithii) and Nuttall saltbush (Atriplex nuttallii) responded positively to increasing residue rate, but were unaffected by fertilization. Smooth brome (Bromus inermis), streambank/thickspike (Agropyron riparium/dasystachyum), tall (Agropyron elongatum) and intermediate (Agropyron intermedium) wheatgrass exhibited significant, although varied, interactive responses to residue and fertilization rate. Total plant biomass was responsive to residue rate, but peaked at a lower rate (90 Mg ha−1) for the native than for the introduced (135 Mg ha−1) mixture. Differences in species and growth form composition occurred among treatments. Maximum diversity occurred at residue rates lower than those for maximum productivity; 45 Mg ha−1 and 90 Mg ha−1 for the native and introduced mixtures, respectively. Diversity was consistently stimulated by fertilization for the introduced species mixture, but responded variably to fertilization for the native mixture.
Nitrate Leaching and Drainage from Annual and Perennial Crops in Tile‐drained Plots and Lysimeters
Authors: Bergström Lars
Published: July 2010

Leaching of NO3 with drainage water from tile‐drained field plots and from three types of lysimeters was estimated during a 4‐yr period. Treatments included barley (Hordeum distichum L.) with and without N‐fertilizer, a grass ley (Festuca pratensis), and a lucerne ley (Medicago sativa) (i.e., 4‐yr forage crops). The maximum amount of NO3 leached was 36 kg N ha−1 yr−1 for barley fertilized with Ca(NO3)2 (120 kg N ha−1 yr−1). For unfertilized barley the corresponding amount was 5 kg N ha−1 during the same period. The NO3 fluxes from the grass and lucerne leys were mostly below 5 kg N ha−1 yr−1. However, after the grass ley was plowed, considerable leaching occurred, reaching 42 kg N ha−1 during 20 weeks following plowing. Weather conditions had a strong influence on the temporal distribution of leaching losses. Lysimeters, compared with tile‐drained plots, had generally higher drainage volumes. The slow dynamics of groundwater beneath the drainage‐tiles can explain most of this difference. Lysimeters with disturbed soil profiles usually had higher drainage volumes than lysimeters with undisturbed profiles. Despite these differences, all methods consistently estimated the relative differences between the cropping systems concerning leaching of NO3. The degree of variation in drainage flow between lysimeter replicates was also satisfactorily low.
Mineralization Potential for Phenol in Subsurface Soils
Authors: Dobbins Durell C. , Thornton‐Manning Janice R. , Jones Daniel D. , Federle Thomas W.
Published: July 2010

The mineralization of 14C‐phenol to 14CO2 was determined in each horizon of four contrasting soil profiles using a modification of the approach used to determine heterotrophic potential in aquatic environments. Short‐term mineralization rates were determined at 12 concentrations ranging from 5 to 10 000 µg phenol kg−1 dry soil and the data were reduced using a hyperbolic saturation model similar to that used for describing enzyme kinetics. The kinetic terms Vmax and K′ were estimated using nonlinear regression. Phenol was mineralized in all soil samples at each concentration examined. The Vmax values ranged from 0.018 to 22.4 ng phenol kg−1 dry soil s−1; K′ values ranged from 20 to 2355 µg phenol kg−1 dry soil. Generally within each soil profile, Vmax tended to decline with increasing depth; however, the magnitude and pattern of this decline varied widely according to soil type. The Vmax in the Ap horizons (3–15 cm) ranged from 2.49 to 13.8 ng kg−1 dry soil s−1. The Vmax in the B22t horizons (30–101 cm) ranged from 0.839 to 2.65 ng kg−1 s−1, and Vmax in the deepest horizons (81–187 cm) ranged from 0.145 to 4.75 ng kg−1 dry soil s−1. This study indicates that soil horizon and soil type are important determinants of the biodegradation of phenol, a potential groundwater pollutant, as it passes through the soil column.
An Ion‐association Model for Highly Saline, Sodium Chloride‐dominated Waters
Authors: Sposito Garrison , Traina Samuel J.
Published: July 2010

An empirical ion‐association model for concentrated aqueous solutions in which NaCl is the principal solute was developed for incorporation into the computer program GEOCHEM. The model involved the use of the Davies equation to calculate the activity coefficients of charged species and other semiempirical equations based in statistical mechanics to calculate the activity coefficients of neutral complexes. Model validation was initiated through prediction of the solubilities of gypsum, amorphous silica, and barite in NaCl solutions and other Na‐salt solutions. Predicted solubilities usually agreed with measured values to within ±5% at ionic strengths up to 2 kmol m−3 (mol L−1). These encouraging results suggest that the model, although limited in scope and validation, will be useful for chemical speciation calculations on highly saline soil solutions and brines.
Residual Effects of Sewage Sludge on Soybean: I. Accumulation of Heavy Metals
Authors: Heckman J. R. , Angle J. S. , Chaney R. L.
Published: July 2010

The potential for excessive crop uptake of heavy metals from land previously amended with sludge is of concern because of the persistence of heavy metals. Field studies were therefore conducted at two locations in 1983 and 1984 to examine the residual effects of sewage sludge on heavy metal uptake by soybean [Glycine max (L.) Merr.]. The Fairland plots (Typic Hapludults) had been amended with two rates of anaerobically degested sludge in 1975. The Beltsville plots (Typic Paleudults) had been established in 1976 with limed‐anaerobically digested, limed‐raw, limed‐compost, or heat‐treated sludge and in 1978 with Nu‐Earth (Chicago, IL) anaerobically digested sludge. Treatments consisted of various sludge rates and pH regimes. The concentrations of metals in soybean shoots at the R4 growth stage varied according to sludge type, application rate, and soil pH. Metal uptake from low metal, limed sludges was similar to that of controls. Metal uptake was, however, increased by unlimed sludges that were high in metal content. Digested sludge linearly increased shoot metal concentrations of Zn, Cd, Cu, and Ni. Compared to the unamended control, soybean Zn increased from 24 to 165 mg kg−1 and Cd increased from 0.06 to 0.25 mg kg−1 at the 112 Mg ha−1 rate. The shoot Cd concentration was over seven times higher from Cd rich Nu‐Earth sludge as compared to the other sludges. Shoot Zn and Cd concentrations exhibited significant linear and quadratic relationships with rates of heat‐treated and Nu‐Earth sludge. There was a greater response of shoot Zn and Cd accumulation to sludge rate at low soil pH. At the 100 Mg ha−1 rate of Nu‐Earth sludge, soybean Zn and Cd concentrations, respectively, were 59 and 1.75 mg kg−1 at soil pH 6.4 and 84 and 2.54 mg kg−1 at soil pH 5.8. These results indicate that sludge composition and soil pH can have a substantial influence on soybean metal uptake for at least 9 yr after the initial sludge application.
Chemistry of Tension Lysimeter Water and Lateral Flow in Spruce and Hardwood Stands
Authors: Joslin J. D. , Mays P. A. , Wolfe M. H. , Kelly J. M. , Garber R. W. , Brewer P. F.
Published: July 2010

The concentrations of H+, NO−3, SO2−4, soluble Al, and undissociated acidity were measured in throughfall, soil solution, and streamflow during five rainfall events on two steeply sloping forested sites in the Great Smoky Mountains. The sources and sinks of these chemical species on a spruce‐birch (Picea rubens Sarg.‐Betula lenta L.) site were compared to those on a hardwood site. The chemistry of water collected in zero‐tension lateral flow collectors during storm events was contrasted with water collected at corresponding depths in tension lysimeters. Tension lysimeter samples from the spruce site had much higher concentrations than those from the hardwood site of H+ (3–7 ×), SO2−4 (1.5–2 ×), Al (2–5 ×), and undissociated acidity (1.5–2 ×). Baseflow from a first‐order stream draining the spruce site was significantly higher in Al and H+ than hardwood site baseflow. On both sites the largest sources of H+ and undissociated acidity were throughfall (incident precipitation + canopy sources) and the O horizon; on the spruce site the O horizon was the predominant source of each. Aluminum and SO2−4 also increased dramatically with passage through the O horizons, especially on the spruce site. Only the spruce site generated appreciable lateral flow. Nitrate, undissociated acidity, and Al concentrations in spruce site lateral flow were not significantly (p <0.05) different from those in corresponding tension lysimeter samples. Electrical conductivity and concentrations of H+ and SO2−4, however, were higher in lateral flow from spruce site B horizons than in corresponding tension lysimeter water. Reduced soil contact time and contact surface area were hypothesized reasons for the ineffectiveness of these B horizon sinks with regard to rapid lateral flow. Lateral flow pathways on the spruce site may have also bypassed sinks for Al and undissociated acidity that exist in the lower mineral horizons and bedrock zone. Stream pH depressions during stormflow may be related to rapid subsurface flow and interflow emanating from these acidic spruce‐birch sites.
Soil Clogging During Subsurface Wastewater Infiltration as Affected by Effluent Composition and Loading Rate
Authors: Siegrist Robert L.
Published: July 2010

The soil clogging effects of wastewater effluent composition and loading rate were investigated in pilot‐scale infiltration cells installed in situ in the structured silty clay loam subsoil of a Typic Argiudoll (fine‐silty, mixed, mesic). Over a 70‐month period domestic septic tank effluent (DSTE), graywater septic tank effluent (GSTE) and tapwater (TW) were intermittently applied in an average of 5.2 doses/d to yield daily loading rates of 1.3, 2.6, and 5.2 cm/d. Soil clogging was negligible in all TW treatments and in the GSTE treatments at 1.3 and 2.6 cm/d. In the GSTE treatments at 5.2 cm/d and in all DSTE treatments, severe soil clogging led to continuous ponding of the soil infiltrative surfaces. A logistic model fit to the experimental data confirmed that soil clogging development was highly correlated with the cumulative mass density loadings of total biochemical oxygen demand and suspended solids. After 62 and 70 months of loading, soil properties were determined with depth. Clogged infiltrative surface zones exhibited significant accumulations of organic materials at the infiltrative surface and within the first few millimeters of the soil matrix. This field study demonstrated that higher quality wastewater effluents can be discharged to subsurface infiltration systems at hydraulic loading rates in excess of those utilized for DSTE without stimulating soil clogging development.
Tilted‐bed Simulation of Erosion and Chemical Runoff from Agricultural Fields: II. Effects of Formulation on Atrazine Runoff
Authors: Wauchope R. Don
Published: July 2010

The concentrations and loads of atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] in runoff water from “tilted‐bed” soil trays under intense simulated rainfall were similar to losses reported in field studies. Atrazine was applied at rates of 2.7 to 3.4 kg/ha as emulsion, wettable powder, dispersible liquid, and dispersible granule formulations, on a loam soil in eight 2.2‐ by 1.2‐m trays tilted to 1.3% slope. In simulated storms in which 3 cm of rainfall fell in 5 min and generated 0.7 cm of runoff, total atrazine losses ranged from 4 to 8% for the emulsion and dispersible‐liquid applications and 9 to 12% for the dispersible‐granule and wettable‐powder formulations. One‐fifth of the total losses occurred in the first liter of the runoff. This initial “flush” loss of atrazine in the water front resulted in concentrations up to 23 mg/L in the first runoff depending on the differing particle sizes of the spray deposits of the different atrazine formulations. The tilted‐bed/rainfall simulator system appears to offer promise as an inexpensive and convenient supplement to field experiments for characterizing pesticide movement or yield in runoff and evaluating the potential of new chemicals for nonpoint source pollution.
Nitrogen Mineralization in Sewage‐sludge‐Amended Coal Mine Spoil and Topsoils
Authors: Voos Gerard , Sabey B. R.
Published: July 2010

A 16‐week laboratory incubation was conducted to determine the rate of net N mineralization in sewage‐sludge‐amended coal mine spoil, two topsoils, a 1:1 mixture of the spoil with each topsoil, and a quartz sand. Sewage sludge was added at rates of 0, 40, 80, and 120 Mg ha−1, which added 0, 1630, 3260, and 4890 kg N ha−1, respectively. The total amount of inorganic N that accumulated during the experiments increased significantly as the rate of sewage sludge addition increased in each of the materials and mixtures tested. However, the rate of sludge addition did not have a similar effect on the amount of NO3‐N accumulated. The soil materials did affect the amount of NO3‐N that accumulated in 16 weeks. Little or no NO3‐N had accumulated in any of the sand treatment samples and only small amounts were produced in the spoil. Ammonium‐N increased with increasing rates of sewage sludge in all materials and mixtures examined. The rate of ammonification was more stable after the 8‐week sampling interval in most cases. Mineralization of organic N added with the sewage sludge varied between 10 to 34%. At all rates of sludge addition, more organic N was minerlized in stock piled topsoil than in the other materials. A nonlinear least squares regression equation for N mineralization as first‐order kinetics slightly overestimates N mineralization in the 4‐ to 8‐week interval and slightly underestimated N mineralized through 16 weeks.
Element Leaching and Capillary Rise in Sandy Soil Cores: Experimental Results
Authors: Sheppard Marsha I. , Thibault D. H. , Mitchell J. H.
Published: July 2010

Disposal of hazardous wastes by burial is a common practice. This practice usually involves several barriers to the migration of the wastes, one of which is the unsaturated soil zone. The long‐term consequences of capillary rise of water and its dissolved contaminants through the unsaturated soil is not easy to assess. Similarly, downward migration after a surface contamination event, such as irrigation with contaminated groundwater, is a complex process. This study examines both the leaching and capillary rise of Tc, I, Np, U, Th, Cs, Cr, and Mo through a sandy soil. Eighty undisturbed soil cores from a forest floor were contaminated, half were contaminated 10 cm from their base to simulate contact with contaminated groundwater (groundwater cores), and the other half were contaminated below the litter layer to simulate soil surface deposition (leaching cores). Cups at the base of the cores served as receptacles for groundwater or for leachate. The cores were placed in the ground with their surfaces exposed to natural rainfall. After 1 yr, half of the cores were exhumed. Soil moisture and temperature conditions in the cores reflected the trends of moisture and temperature at the coring site. Leachate analyses and exhumation data of the leaching cores indicated element mobility as Tc ≥ I >> Mo ≥ Cr >>> U ≥ Np, Cs, Th, with Tc the most mobile and Th the least mobile. Only Tc, I, Mo, and Cr passed through the cores in the leachate in the first year. The groundwater cores showed that Tc, I, Mo, and Cr are most likely to reach surface soils from contaminated groundwater based on one year of data. Partition coefficient (Kd) values for Tc, I, and U from batch sorption experiments were compared with Kd values obtained from the exhumation porewater and soil, by soil horizon.
Speciation of Trace Inorganic Contaminants in Plants and Bioavailability to Animals: An Overview
Authors: Cataldo D. A. , Wildung R. E. , Garland T. R.
Published: July 2010

The movement of both essential and pollutant trace elements through agricultural food chains is a complex problem, influenced in part by plant‐mediated changes in trace element speciation that may alter the rate and extent of gastrointestinal absorption after ingestion of plant tissues by animals. An overview is provided of a series of investigations undertaken to describe the processes governing the chemical behavior of several cations (Pu, Ni, Cd, and Fe) and anions (Tc, Se, and S) during transport in the plant xylem and after deposition in plant tissues. Cations were generally present in xylem exudale as organic acid, amino acid, and peptide complexes specific to the element, whereas anions tended to remain in the inorganic forms initially absorbed by the root. Once deposited in tissues, both cations and anions were associated with more complex, but soluble, plant metabolites. The cations (Pu, Ni, Cd) were directly associated with >10 000 molecular weight proteins, whereas the anions (Se and Tc) appeared to undergo chemical reduction and incorporation into proteins using enzymatic processes functioning for S metabolism. The importance of these plant processes on gastrointestinal absorption was demonstrated for Pu and Tc, which differed markedly in their behavior in plants and animals.
Characterization of Soluble Organic Compounds and Complexation of Copper, Nickel, and Zinc in Extracts of Sludge‐amended Soils
Authors: Dudley L. M. , McNeal B. L. , Baham J. E. , Coray C. S. , Cheng H. H.
Published: July 2010

An anaerobically digested, municipal sewage sludge was mixed with an acid and a neutral soil and incubated for periods of up to 30 weeks at 25 ± 2°C and approximately −33 kPa water potential. Aliquots from saturation pastes were passed through a Sephadex™ G‐15 gel filtration column and the fractions analyzed for total soluble C, Cu, Ni, and Zn. Infrared spectra were recorded for fractions containing a soluble‐C or metal‐concentration maximum. Copper was associated with soluble organic compounds throughout the 30‐week incubation, and through 4 weeks was found primarily in fractions containing amide functional groups. Zinc generally eluted in a region suggesting the presence of Zn‐inorganic complexes. Soluble Ni was associated with organic compounds at high pH during the initial 4 weeks of incubation, but in extracts of subsequent incubations the element partitioned about evenly between organic and inorganic complexes below neutral pH. The relative strength of adsorption bands in the IR spectra, which were diagnostic for polysaccharides, proteins, and amino acids, declined over the study period. The dominant spectral features for extracts of sludge‐soil mixtures incubated 4 weeks or longer were diagnostic bands for aromatic and aliphatic carboxylic acids. A least squares (L2) approximation to proton titration curves was used to select a subset of ligands, which provided the smallest error term. The set of ligands from which the subset was selected was acetate, citrate, maleate, phthalate, salicylate, arginine, lysine, ornithine, and valine. Total soluble concentrations of Ca, Cu, Ni, Zn, Cl, NH3, PO4 and organic ligands, and pH and PCO2 values (0.03 kPa), were used to calculate ion speciation in the extracts via the computer program GEOCHEM. Values for the fractions of total soluble Cu, Ni, and Zn bound by soluble organic matter as predicted by GEOCHEM agreed with values determined by gel separation.
Nitrous Oxide Production throughout the Year from Fertilized and Manured Maize Fields
Authors: Cates R. L. , Keeney D. R.
Published: July 2010

Two field sites on a loam soil were established to monitor N2O concentration in the soil atmosphere and rate of emission from the soil surface. The sites were cropped to maize (Zea mays L.) and managed at two high‐N levels (181 or 237 kg N ha−1). Both sites received 168 kg N ha−1 as feedlot cattle (Bos taurus) manure (preplant‐incorporated) and 13 kg N ha−1 as NH4NO3 fertilizer in the row at planting. One site (Site B) received additional soil‐incorporated N (56 kg N ha−1) as urea. Fluctuations in N2O emissions from the two sites were temporally similar, and differed only in magnitude with Site A (no additional fertilizer), emitting about 3.6 kg N2O‐N ha−1 yr−1 and Site B about 5.2 kg N2O‐N ha−1 yr−1, or about 2% of the N applied. Most of the N2O was emitted between mid‐June and the end of July when the soil was warm and NH+4‐N was present, and at spring thaw (late March the following year) when soils were cold and near water‐saturated. High N2O emissions during the growing season occurred following precipitation events, and hence were associated with high soil water and probably with the initiation of soil drying. Nitrous oxide production was continuous during winter months, presumably a result of denitrification. The N2O concentration in the profile of the frozen soil increased to high levels (nearly 2000 µL L−1 N2O at Site B) before spring thaw. At thaw, nearly 330 d after application of the N amendments, an apparent physical release period occurred and N2O flux was far higher (about 50 g N2O‐N ha−1 d−1) than at most times during the growing season.
Trees as Monitors of Tritium in Soil Water
Authors: Kalisz P. J. , Stringer J. W. , Volpe J. A. , Clark D. T.
Published: July 2010

Tritium (3H) activities in the foliage of forest trees were found to reflect 3H activities in soil water along the perimeter of a retired low‐level radioactive waste disposal site. Spatial variability in foliage 3H activity clearly delineated patterns of 3H in soil water as deep as 3 m. Late summer increases in foliage 3H activity paralleled increases in soil water activity and also suggested greater uptake of water from deep reservoirs after surface soils had dried out. White and chestnut oak (Quercus alba L. and Q. prinus L.) dominated the study area and were good monitors of 3H, regardless of tree size. Spatial patterns of 3H in foliage of these species over a 5‐ha watershed were interpretable in terms of the local landscape and the probable pathways of movement of contaminated water originating on the disposal site. Results of this study suggest that trees and other deeply rooted plants may serve as simple and effective monitors of soil water contamination and may therefore be useful additions to permanent monitoring systems.