bluuebunny/crossref_metadata_2025 huggingface dataset:
Residues from Organic Arsenical Herbicides in Chemically Thinned Forests
Authors: Newton Michael
Published: July 2010

Conifers in four Pacific Northwest locations and forest types were stem‐injected with the organic arsenicals cacodylic acid and monosodium methanearsonate (MSMA), herbicides used for forest thinning and insect control. Concentrations and locations of As residues in tree stems, twigs, foliage, and in litter and soil were determined. Within each forest type, spring treatment led to somewhat higher concentrations in crowns than did fall application; differences were larger with cacodylic acid than with MSMA. Most residue concentrations were in the range of 20 to 60 mg As/kg (dry‐weight basis). Trees killed 5 yr earlier showed As concentrations of 122 to 670 mg/kg in the phloem just above the injection sites, 10.9 to 25.0 mg/kg in the xylem, and 34.7 to 77.8 mg/kg in upper lateral twigs and terminal leader shoots. Residues in litter were lowest (5–9 mg/kg) in Douglas‐fir [Pseudotsuga menziesii (Mirb.) Franco] stands and highest (27–46 mg/kg) in lodgepole pine (Pinus contorta Engelm.) stands. Surface soil concentrations below the litter traps increased 0 to 3.7 mg As/kg over native soil concentrations of 1 to 7 mg/kg. Most observations were within the range of naturally occurring As in these sites. Persons using fuel from treated stands probably would not receive measurable exposure to toxic forms of As. Residues in fuelwood would be minimized if wood at the point of injection and bark on the lower stem were excluded from the fuel. Bark removal is made easy by injecting arsenicals in the fall.
Molybdenum Accumulation by Corn and Soybeans from a Molybdenum‐rich Sewage Sludge
Authors: Pierzynski Gary M. , Jacobs Lee W.
Published: July 2010

An anaerobically digested sewage sludge containing 1500 mg Mo/kg was applied to add 0 to 300 kg Mo/ha in two separate experiments. This field study was conducted with corn (Zea mays L.) and soybeans [Glycine max (L.) Merr.] over a 3‐yr‐period to evaluate high Mo additions to soils from the application of Mo‐contaminated wastes. A total Mo analysis of soils sampled after the third growing season accounted for 97% of the applied Mo in two sludge treatments. Concentrations of Mo in whole plant, diagnostic tissue, and grain samples from both crops were significantly increased with any sludge treatment. Lime residues in the sludge increased soil pH's from 4.8 to 7.1 resulting in further Mo accumulation in the plant samplings. Four soil extractants [1.0 M NH4HCO3 + 0.005 M DTPA, 1.2 M NaC2H3O1,Tamm's acid ammonium oxalate, and 0.5 M (NH4)2HPO4] in combination with soil pH were evaluated for their ability to predict Mo concentrations in the plant samplings. Soil pH became significant in the prediction equations when considering more than 1 yr of data. None of the extractants were proven to be clearly better or worse than the others. Further testing of the ammonium bicarbonate‐DTPA extractant is recommended because of its potential for simultaneous use with other plant nutrients and heavy metals in the soil during multielement analysis, as well as the ease by which it can be analyzed using plasma emission.
Effect of Simulated Acid Precipitation on Soil Microbial Activity in a Typic Quartzipsamment
Authors: Will M. E. , Graetz D. A. , Roof B. S.
Published: July 2010

The effects of acid precipitation on microbial and enzyme activities were determined in a field study near Melrose, FL. Three transects of two plots each were irrigated with lake water acidified with 7:3 (v/v) H2SO4/HNO3 to pH 3.0 or 3.6, or with unacidified lakewater (pH 4.6, control) at a rate of 10 cm/week for 20 weeks. The experimental plots were divided into covered and uncovered subplots to determine the effect of excluding natural rainfall (pH 4.6). The application of 200 cm of simulated acid precipitation did not significantly influence soil pH, respiration, or arylsulfatase activity. Phosphatase activity decreased under the pH 3.0 treatment and urease activity was stimulated by the pH 3.6 treatment. The amount of N mineralized over a 12‐week incubation period was lower in soil from the pH 3.0 treatmenthan in soil from the pH 3.6 and 4.6 treatments. After the application of 200 cm of simulated acid rain; soil pH, respiration, and phosphatase activity levels were lower in the plots protected from natural rainfall. Twenty‐four weeks after the last acid application there were no differences in any of the measured parameters between the pH treatments.
Plant Availability of Phosphorus in Sewage Sludge Compost
Authors: McCoy J. L. , Sikora L. J. , Weil R. R.
Published: July 2010

Field and greenhouse studies were conducted to compare the effectiveness of Blue Plains sewage sludge compost (BLU), Parkway sewage sludge compost (PAR), and triple superphosphate (TSP) as sources of P for corn. These amendments were applied to a Sassafras sandy loam (Typic Hapludults) in a field study and to the Sassafras soil and a Christiana silty clay loam (Typic Paleudults) in a greenhouse study. First‐year application rates in the field study ranged from 0 to 1500 kg total P/ha. Plots were split the second year with one‐half receiving no additional P and one‐half receiving P equal to 1st‐yr rates. Nitrogen as NH4NO3 was applied at variable rates to plots so that the total assumed available N equaled 180 and 219 kg N/ha for the 1st and 2nd yr, respectively. Dry matter yield and P uptake were measured at the eight‐leaf stage (V8) and at maturity. Below the 100 kg P/ha rate, there were no significant differences in P uptake or yield among the different sources and rates of P. Above the 100 kg P/ha rate, TSP but not the composts, significantly increased growth and P uptake by corn in both field and greenhouse studies. The TSP was approximately four to seven times more effective than either compost in raising tissue P concentration in corn (Zea mays L) ear leaves. A maximum of 2.05 and 11.2% of the P applied as compost and TSP, respectively, was taken up by the corn. Soil P extracted by the dilute double acid (0.5 M HCl and 0.0125 M H2SO4) and 0.5 M NaHCO3 methods increased with increasing P application from all sources. Extractable soil P by both methods correlated well with total P uptake from TSP but did not correlate well with P uptake from the composts. A P fractionation indicated that most of the compost P was associated with Fe and Al and only 2 to 5% was in organic forms. The Fe‐bound P fraction of the amended soils increased with increasing P application from all sources. Two factors appeared to control the P uptake response of corn: the treatment of the wastewater to remove P at the sewage treatment plant, and the P fixing capcity of the soil.
Sediment Losses from Forest Management: Mechanical vs. Chemical Site Preparation After Clearcutting
Authors: Beasley R. S. , Granillo A. B. , Zillmer V.
Published: July 2010

The comparative effects of mechanical and chemical site preparation on water yields and sediment losses following forest clearcutting were evaluated over a 4‐yr period in the Athens Plateau area of southwestern Arkansas. After 1 yr of pretreatment measurements, three forested watersheds were clearcut and the residual vegetation and debris were sheared and windrowed but not burned. Three watersheds were clearcut in a similar manner, but received chemical site preparation. Residual trees on two watersheds were injected with 2–4,D amine; the third watershed was aerially sprayed with a mixture of Tordon® (active ingredient; picloram [4‐amino‐3,5,6‐trichloropicoline acid]) and Garlon® (active ingredient; triclopyr [3,5,6‐trichloro‐2‐pyridinyloxyacetic acid]). Three additional watersheds were left undisturbed for controls. Mean annual sediment losses on the mechanically, site prepared watersheds during the first posttreatment year were significantly higher than those from either the chemically site prepared watersheds or controls. Chemical site preparation did not significantly increase sediment losses. Although 2nd yr losses for the mechanical site preparation and control treatments doubled over 1st‐yr levels, no significant treatment effect was detected for either site preparation treatment. Third‐year losses decreased below 1st‐yr losses for all treatments but not to pretreatment year levels. The relatively sharp declines in sediment losses during the third posttreatment year were attributed to rapid regrowth of natural vegetation on the sites.
Carbon and Nitrogen Mineralization Kinetics for Poultry Litter
Authors: Gale P. M. , Gilmour J. T.
Published: July 2010

An incubation study was conducted to evaluate the relationship between net C and net N mineralized during the decomposition of surface‐applied poultry (Gallus gallus) litter. The two litters studied were passed through a 2‐mm sieve and comparisons were made among the fine and coarse fractions, and a 50:50 mixture of these fractions. Carbon mineralization for the fine fraction, as measured by CO2 evolution, followed first‐order kinetics. Three distinct phases of decomposition were observed. Rapid phase rate constants followed the Arrheniuns equation for the 11 to 25°C temperature range, while slow and intermediate phase rate constants at 18 and 25°C were temperature independent. The fine fraction C mineralization rate constants for the rapid phase were 0.018, 0.038, and 0.049 d−1 at temperatures of 11, 18, and 25°C, respectively. For the intermediate and slow phases, rate constants at 25°C were 0.011 and 0.006 d−1, respectively. At 25°C, the rapid phase rate constant for the course fraction was 0.041 d−1 and that of the mixture was 0.046 d−1 . No effect due to size fraction was observed for the intermediate and slow phases. During the rapid phase, net N mineralization paralleled net C mineralization after an initial flush of N mineralization at 1 d. In a comparison among temperatures, the linear relationship between net N mineralized and net C mineralized had a slope of 0.62 for the fine fraction of both litters. The parallel intercepts for this relationship, 160 g N (kg N)−1, for pine (Pinus spp.) shavings and 116 g N (kg N)−1 for wheat (Triticum aestivum L.) straw litter, correlated well with the N mineralized in 1 d, as determined in a separate experiment. In a comparison among fractions, coarse, fine, and mixed fractions had slopes of 0.52, 0.64, and 0.25, respectively, at 25°C. The intercept for the coarse fraction was 65 g N (kg N)−1 with no differences due to litter type. However, differences due to litter type were observed for the fine and mixed fractions.
Nitrogen Transformations in Ponds Receiving Polluted Water from Nonpoint Sources
Authors: Reddy G. B. , Reddy K. R.
Published: July 2010

A laboratory study was conducted to determine the role of N transformations in ponds receiving inorganic N‐rich effluents from septic fields, agricultural, and pasture watersheds. Undisturbed sediment columns were obtained from three ponds. Floodwater in the columns was enriched with either 15NH+4‐N or 15NO−3‐N. Ammonium removal rates ranged from 55 to 85 mg N m−2 d−1, while NO−3‐N removal rates ranged from 48 to 71 mg N m−2 d−1. Twenty‐three to 49% of floodwater 15NH+4‐N diffused into the sediment during a 22‐d incubation period and was recovered in 15NH+4‐N (6–12% of the floodwater 15NH+4‐N) and organic 15N fractions (14–37% of the floodwater 15NH+4‐N). When 15NO−3‐N was added to the floodwater, about 7% was tied up in the sediment. Ponds receiving effluents from septic tanks and pastured areas retained less floodwater N in the sediment compared to sediments of the pond receiving runoff from agricultural watershed.
Vapor‐phase Diffusion of Benzene in Soil
Authors: Karimi Ali A. , Farmer Walter J. , Cliath Mark M.
Published: July 2010

The volatilization of benzene (C6H6), a component of volatile emissions from landfills receiving certain industrial wastes, was characterized in the laboratory using a simulated landfill apparatus. The steady‐state vapor diffusion of C6H6 in soil under isothermal conditions and negligible water flow was directly related to soil air‐filled porosity. The volatilization flux of C6H6 through a soil cover was greatly reduced by increased soil bulk density and increased soil‐water content. The actual flux through the soil cover could be predicted from the soil porosity term, P10/3a P−2T, where Pa is the soil air‐filled porosity and PT is the total porosity. The diffusion coefficient in air for C6H6 calculated from the experimental results was 8.91 × 10−6 m2 s−1, at 20 °C, which agrees with other reported data.
Effects of Sulfur Dioxide on Nitrogen Fixation, Carbon Partitioning, and Yield Components in Snapbean
Authors: Griffith S. M. , Campbell W. F.
Published: July 2010

The air pollutant SO2 is known to affect plant biochemistry and physiology, although very little is known about its effects on N2‐fixation in legumes. This study sought to determine if N2‐fixation, C partitioning, and plant productivity of snapbean (Phaseolus vulgaris L.) were affected under short‐term, low‐level SO2 exposures. Plants were exposed, 29 d after planting (7 d before anthesis), to 0, 18, and 36 µmol SO2 m−3 for 4 h d−1 for 5 d in a fumigation chamber. On the last day of SO2 treatment, plants were also exposed to 14CO2 to determine changes in C partitioning patterns. At these concentrations, there was no visible damage to plant tissue and no significant changes in dry weight or yield components. Only the 36 µmol SO2 m−3 treatment reduced C2H2 reduction rates, but recovery to near control rates occurred within 24 h after SO2 removal. Leaves of plants treated with 18 µmol SO2 m−3 exported more of their total assimilated 14C than control plants, while those treated with 36 µmol SO2 m−3 retained greater amounts. Retention of 14C at the 36 µmol SO2 m−3 level may account for the inhibition of C2H2‐reduction because of less photosynthate arriving at the root nodules. These data suggest that SO2 levels that do not cause visible injury may interfere with C metabolism and transport in snapbean.
Characterization of Iron and Zinc in Albuquerque Sewage Sludge
Authors: Knudtsen Karen , O'Connor G. A.
Published: July 2010

Chemical forms of Fe and Zn present in anaerobically digested sewage sludge from Albuquerque, NM were identified and quantified. Water‐soluble Fe and Zn were speciated based on charge and stability of metal complexes, and on their degree of association with soluble organics. Chemical forms of Fe and Zn present in the solid phase of the sludge were characterized with a sequential extraction procedure. Soluble Fe was predominantly present as negatively charged slowly labile organic complexes of molecular weights > 1000 daltons. Zinc was associated with negative and neutral species that were very or moderately labile, according to the techniques used. The contribution of soluble organics to the chemistry of Fe and Zn was evaluated using gel chromatography. Iron was associated with a larger portion of sludge organics and with larger molecular weight fractions than Zn complexes. The percentage of total sludge Fe and Zn found in readily soluble forms was very small (<1%). The amounts may nevertheless represent significant pools of metal forms available for plants. Zinc was found in larger concentrations than Fe in the potentially more labile, organic, and carbonate fractions of the sludge. The Albuquerque sludge is an excellent source of Fe and Zn to plants because it contains readily soluble forms of these metals that may be maintained in soil solution through organic complexation.
Swine Manure and Lagoon Effluent Applied to a Temperate Forage Mixture: II. Rainfall Runoff and Soil Chemical Properties
Authors: Westerman P. W. , King Larry D. , Burns J. C. , Cummings G. A. , Overcash M. R.
Published: July 2010

Rates of swine (Sus scrofa domesticus) waste used for crop production must be sufficient to supply adequate nutrients but must not pose a surface or groundwater pollution hazard. To determine acceptable rates, plots of predominantly tall fescue (Festuca arundinacea L. Schreb) on a Cecil soil (Typic Hapludults) received no treatment (C); commercial fertilizer (F) at 201‐34‐65 kg N‐P‐K ha−1 yr−1, swine manure slurry (M) supplying 670 kg N ha−1 yr−1, or swine lagoon effluent (E) applied by sprinkler irrigation to supply 600 (E1) or 1200 (E2) kg N ha−1 yr−1 for 4 yr. The waste treatments, chosen to evaluate acceptable maximum application rates when land is limited, resulted in much higher applications of N, P, K, and other nutrients than are normally used for temperate species. Runoff from E2 had an annual mean concentration of 13 mg L−1 NO3‐N but the low runoff volume resulted in mass transport of only about 10 kg NO3‐N ha−1 yr−1. Concentration of P was significantly higher with E2 (9 mg L−1) and M (6 mg L−1) than with the other treatments. The runoff quality from E1 was not significantly different than that from F. Soil NO3‐N concentrations to a depth of 200 cm showed significant differences in the order E2 = M > E1 > F = C. For E2, 49% of the applied N could not be accounted for by crop removal, increased soil NO3‐N, or runoff. Mehlich 1 extractable P was greater with E2 than with the other treatments. Extractable soil K and Na were increased by E1 and E2 but treatments had little or no effect on extractable Ca, Mg, Cu, Zn, Mn, or on total N, organic matter, or pH. Analysis of runoff and soil NO3‐N data indicate that M, E2, and perhaps E1 supplied excess N. Consequently, surface and groundwater pollution hazards may be created by applying manure and effluent at the rates studied. Pollution by runoff was more likely when rainfall occurred soon after manure or fertilizer application.
Natural Mycorrhizal Colonization of Pines on Reclaimed Surface Mines in Virginia
Authors: Schoenholtz Stephen H. , Burger James A. , Torbert John L.
Published: July 2010

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

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

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

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

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

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

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

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

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

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

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

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

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

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

To assess the availability of sludge‐borne Cd and Zn over time, corn (Zea mays L.) and soil (Typic Hapludoll silt loam) were sampled for 6 yr following termination of three annual applications of sewage sludge. Cumulative sludge applications totaled 0, 60, 120, and 180 Mg ha−1. Sludge treatments consistently resulted in greater Cd and Zn accumulation in stover than did the control treatment for each of the 6 yr following the final sludge application. Cadmium and Zn concentration in stover increased linearly within treatment levels for all years. Concentrations of Cr, Cu, Ni, and Pb in stover and grain fluctuated annually, with no predictable effect of sludge rate. Of the metals measured in stover and grain, only stover Cd exceeded the suggested National Research Council tolerance level of 0.5 mg kg−1 in animal feed for all sludge treatments in all years. Cadmium uptake decreased over time at all sludge rates, and was inversely related (P > 0.01) to time in years following terminal application. Zinc uptake declined slightly over time, although not to the same degree or with the same predictability as Cd uptake. Soil Cd and Zn extractable with DTPA and 1 M HNO3 were highly correlated with plant metal uptake within years. However, metal uptake diminished with consecutive croppings for constant levels of extractable Cd and Zn. Hence, the reliability of either DTPA or 1 M HNO3 in the prediction of Cd and Zn uptake in subsequent croppings is questionable.
Model for Long‐term Phosphate Reaction Kinetics in Soil
Authors: van der Zee Sjoerd E. A. T. M. , van Riemsdijk Willem H.
Published: July 2010

A simplified reaction kinetics model for long‐term P‐sorption in soils receiving large quantities of P‐rich animal manure is presented. Results from soil analyses for samples taken in 84 fields in nine different soil types indicate that the oxalate extractable P provides a good estimation of total P. Sorption experimental data for reaction periods up to 249 d show that measured sorption is proportional to In(t). Total sorption, F, (at long reaction periods) that includes P already present (Pox) appears to be proportional to the sum,M, of oxalate‐extractable Fe and Al. These results are described with a model where soil reactivity is related linearly to M, and the reaction kinetics are expressed in terms of a composite concentration time variable, I. This leads to the relationship F = kM In(I), where k is a characteristic of the soil. Comparisons with results in literature indicate that the concentration dependence of the reaction is accurately described by using I instead of time as a variable. Differences in reactivity (k) for different soil horizons or soil types are apparent from the different k values for topsoils and subsoils. Sorption measured during 40 h (Fr) may be extrapolated to long‐term (1–2 yr) sorption (Fm) for each soil separately without correction of the value of I for the reaction period in the field by simply setting Fm = Pox + 1.8 Fr. For a P concentration of 5 mmol L−1 this leads to a value of αm = Fm/M = 0.63 ± 0.14 for topsoils. Extrapolation using the average k value found for short‐term sorption experiments results in the same value of αm.
Metal Availability in Sludge‐amended Soils with Elevated Metal Levels
Authors: Rappaport B. D. , Martens D. C. , Reneau R. B. , Simpson T. W.
Published: July 2010

Field studies were conducted in 1984 with in situ controlled lateral flow plots to determine Cd, Cu, Ni, and Zn availabilities for corn (Zea mays L.) grown on sludge‐amended soils. These plots were constructed in Bojac loamy sand (Typic Hapludult), Davidson clay loam (Rhodic Paleudult), and Groseclose silt loam (Typic Hapludult) located in the Coastal Plain, Piedmont, and Ridge and Valley provinces of Virginia, respectively. An aerobically digested sludge from a wastewater treatment plant with major industrial inputs was applied to the soils at rates of 0, 42, 84, 126, 168, and 210 dry Mg ha−1. The highest sludge rate supplied 4.5 kg Cd, 760 kg Cu, 43 kg Ni, and 620 kg Zn ha−1. Corn grain and stover yields at the three locations increased linearly as a function of increased rate of sludge application (r2 ≥ 0.92**, significant at the 0.01 level). Metal concentrations in corn grain and earleaves from all treatments on the three soils were within normal levels. Nonsignificant relationships occurred between levels of DTPA‐extractable Cd, Cu, Ni, and Zn and the respective metal concentration in corn earleaves for data combined over the three soils. Amounts of DTPA‐extractable Cd, Cu, Ni, and Zn in the Ap horizon of the three soils increased linearly (r2 = 0.76** to 0.88**) with rate of sludge application. Maximum DTPA‐extractable metal levels in the soils were 0.6 mg Cd, 150 mg Cu, 4.0 mg Ni, and 75 mg Zn kg−1. The order of DTPA‐extractable metal concentrations in the soils, Cu > Zn > Ni > Cd, paralleled the amounts of metals applied via sludge application. Phytotoxicity did not occur in the corn grown on these diverse soils, even where Cu and Zn were applied in excess of USEPA guidelines.
Tall Fescue Production and Nutrient Status on Southwest Virginia Mine Soils
Authors: Roberts J. A. , Daniels W. L. , Bell J. C. , Martens D. C.
Published: July 2010

Tall rescue (Festuca arundinacea Schreb.) is a hardy grass species commonly used in surface mine reclamation and soil conservation. This study documented changes in fescue production (five growing seasons) and nutrient status (three growing seasons) as influenced by spoil type and various amendments. In Exp. I, fescue growth and nutrient status on five mixes of fertilized sandstone (SS) and siltstone (SiS) spoils were compared. A 2:1 SS/SiS control and treatments of 112 Mg ha−1 sawdust, native topsoil, and 22, 56, 112, and 224 Mg ha−1 municipal sewage sludge were compared in Exp. II. Standing biomass was measured in 1982–1984 and 1986 and tissue nutrient levels were measured in 1982–1984. High SiS spoils inhibited initial biomass production in Exp. I, but parent material effects diminished with time. All spoil mixes maintained adequate fescue production for five growing seasons, primarily due to small annual N additions (56 kg ha−1). In Exp. II, highest yields were maintained on ≥56 Mg ha−1 sludge treatments. Fescue production declined consistently through 1984 in all other treatments, probably due to N stress. Fescue production was highest the second year (1983) in all treatments of both experiments, but dropped sharply in 1984. Overall results indicate N was most limiting to production in the short term, but P becomes limiting over time. Sludge‐amended soils supported higher N, P, and cation tissue concentrations. Total P uptake appeared to be limited by low N levels, even when adequate soil P was available. potassium uptake rates greatly exceeded K fertilizer applications. Heavy metal uptake was not a problem, even in very high sludge treatments. Sludge‐amended mine soils were superior to both native topsoil and inorganically fertilized spoils in their ability to sustain long‐term fescue production without periodic augmentation.
The Influence of Selenium, Salinity, and Boron on Alfalfa Tissue Composition and Yield
Authors: Mikkelsen R. L. , Haghnia G. H. , Page A. L. , Bingham F. T.
Published: July 2010

Alfalfa (Medicago sativa L.) was grown in greenhouse sand culture to determine the effects of Se(VI), SO2−4‐salinity and B on alfalfa tissue composition and yield. A 4 × 2 × 2 factorial experiment was conducted with treatments consisting of four Se concentrations (0, 0.25, 0.5, and 1.0 mg Se(VI) L−1 as Na2SeO4), two B concentrations (0.5 and 3.0 mg B L−1 as H3BO3), and two salinity levels (0.5 and 5.0 dS m−1 as Na2SO4 and CaSO4·2H2O). Three cuttings were made and the vegetative portions analyzed for dry weight and total Se, S, and B. Plant yields were significantly reduced by both salinity and Se(VI) but not by B. Tissue Se concentrations were positively correlated with Se in the irrigation water but negatively correlated with SO2−4‐salinity and B. Plant Se was reduced from 620 mg Se kg−1 to less than 7 mg Se kg−1 in the presence of SO2−4‐salinity. A synergistic effect between Se and S was found at the basal nutrient concentration of SO2−4 (0.5 mM). Tissue S was increased from less than 3 g S kg−1 to over 10 g S kg−1 with the addition of 1 mg Se L−1. Alfalfa can potentially accumulate extremely high concentrations of Se when exposed to soluble Se(VI) in the root zone.