bluuebunny/crossref_metadata_2025_split huggingface dataset:
Field Decay of Wheat Straw and its Effects on Metribuzin and S‐Ethyl Metribuzin Sorption and Elution from Crop Residues
Authors: Dao Thanh H. 
Published: July 2010

AbstractBest agricultural management practices (BMP) are needed for minimizing the potential off‐site transport of agricultural chemicals while retaining their chemical efficacy. Field and laboratory studies of herbicide‐crop residue interactions in conservation tillage systems were conducted to determine weather‐induced changes in wheat (Triticum aestivum L.) straw chemical composition, the capacity of plant residues to retain metribuzin [4‐amino‐6‐(1,1dimethyl‐ethyl)‐3‐(methyl‐thio)‐1,2,4‐triazin‐5(4H)‐one] and its S‐ethyl analog (S‐ethyl metribuzin), and the changes in herbicide sorption characteristics of these residues as they decay in the field. At harvest, undecayed wheat straw exhibited Freundlich straw‐water partition coefficients of 13.1 and 24.2 µmol kg−1/(µmol L−1)1/n, where 1/n = 0.78 and 0.60 at 20 °C for metribuzin and S‐ethyl metribuzin, respectively. Lignin accounted for the majority of the sorption capacity of intact wheat straw. The purified cellulose fraction did not significantly sorb the herbicides. Increased sorption capacity of decaying straw was associated with a decline in cellulose concentration or conversely the lignin enrichment of the straw. Field decay reduced straw cellulose concentration at the rate of 1.56 × 10−3 d−1 for straw in partial contact with the ground, following grain harvest in 1983, and 3.97 × 10−4, and 4.39 × 10−4 d−1 for standing straw in 1985, and 1986, respectively. Observed asymmetrical breakthrough curves of both chemicals from packed straw columns also suggested a slow mechanism of release of the herbicides from crop residues. Wheat straw's affinity could reduce herbicidal efficacy of soil‐activated chemicals if they were applied as a surface spray in conservation tillage systems. Although metribuzin and S‐ethyl metribuzin are primarily soil‐activated herbicides, they would still be effective for post‐emergence control of Bromus spp. in winter wheat due to foliar absorption and slow release from the straw mulch. By the same token, the straw mulch is a temporary storage medium to alter these herbicides' environmental dispersion pattern and may be a significant mechanism of retardation of agricultural chemical movement to the subsurface of lands under conservation tillage.
Water Quality Impacts Associated with Wheat Culture in the Southern Plains
Authors: Smith S. J. , Sharpley A. N. , Naney J. W. , Berg W. A. , Jones O. R. 
Published: July 2010

AbstractWater quality information regarding wheat culture in the Southern Plains is sparse. The objective of this study is to determine the extent to which the area's surface and ground‐water quality is influenced by different wheat cultural practices. Concentrations and amounts of sediment, N and P in surface runoff water were determined for conventional till (CT), reduced till (RT), and no till (NT) wheat (Triticum aestivum L.) watersheds in the High Plain, Reddish Prairie, and Rolling Red Plain land resource areas of Oklahoma and Texas. During the 4 to 6 yr study periods, RT and NT practices were superior to CT for reducing sediment and associated particulate nutrient discharge. Mean annual discharge ranged from 230 to 15 900 kg ha−1 for sediment, 1 to 27 kg ha−1 for total N, and 0.1 to 6 kg ha−1 for total P. Irrespective of tillage practice, annual soluble nutrient losses in surface runoff water tended to be small, often < 1 kg ha−1 N or P. Successful prediction of soluble P, particulate P, and particulate N losses was achieved using appropriate kinetic desorption and enrichment ratio procedures. Soluble N in runoff posed no particular water quality problem, but recommended P levels were exceeded, even from baseline, unfertilized grassland watersheds. With regard to groundwater quality, elevated levels of NO−3 (e.g., 34 mg N L−1 maximum) were observed on one Reddish Prairie NT watershed.
Relations among NaOH‐Extractable Phosphorus, Suspended Solids, and Ortho‐Phosphorus in Streams of Wyoming
Authors: Parker Michael 
Published: July 2010

AbstractDuring 1984–1986, 369 water samples from seven streams and a sewage treatment plant in Wyoming were analyzed for NaOH‐extractable P (NaOH‐P; a possible index of biologically available P), ortho‐P (OP), and suspended solids (SS). Regressions predicting NaOH‐P were developed from data on SS and OP, plus information on variability in time (year of sampling), meteorology (volume discharge), and presence/absence of beaver (Castor sp.) dams. Scatter plots, ANOVA, and cluster analyses indicated data could be aggregated into four groups reflecting processes that differ among the eight stations (e.g., relations among volume discharge, SS, and OP). These groups are composed of one to three stations, and index a component of spatial variability. Adjusted R2 and precision (95% confidence limits for the mean) always tended to be poor when OP was more influential in affecting NaOH‐P than were SS (R2 = 21–88%); only in some cases where SS were highly influential were adjusted R2 and precision good. If data presented are representative, then the best precision obtainable from regressions will be about ±50% of the mean value for NaOH‐P. This value compares favorably with many other techniques, so predicting NaOH‐P from regressions should be useful for some applications.
Measurement and Characterization of Macropores by using AUTOCAD and Automatic Image Analysis
Authors: Singh Piyush , Kanwar Rameshwar S. , Thompson Michael L. 
Published: July 2010

AbstractMacropores (with equivalent diameters greater than 1600 µm) were quantified under no‐till and conventional tillage practices by using AUTOCAD and automatic image analysis. To quantify macropores, undisturbed soil blocks (50 by 50 cm) were impregnated with plaster of paris slurry. After the plaster of paris set, soil layers were taken out in 5‐cm increments to a total depth of 60 cm. At each soil plane pictures were taken by a 35‐mm camera and macropores were traced on transparent acetate sheets. The pictures and transparent sheets were analyzed by using an automated image analyzer and AUTOCAD, respectively, for total number, perimeter, area, and size frequency distribution of macropores. The AUTOCAD method proved to be simpler and better than the image analysis technique. Larger and continuous cracks accounted for greater macropore area in conventional tillage sites than in no‐till sites. On the other hand, more worm holes and root holes accounted for a greater number and larger perimeters of macropores in no‐till sites in comparison to conventional tillage sites.
Positional, Spatially Correlated and Random Components of Variability in Carbon Dioxide Efllux
Authors: Aiken R. M. , Jawson M. D. , Grahammer K. , Polymenopoulos A. D. 
Published: July 2010

AbstractThe ability to distinguish spatial variability either from deterministic trends or from experimental treatment effects contributes to the accuracy and interpretation of field experiments. The objective of this study was to characterize three components of soil and soil plus vegetation CO2 efllux: the positional trend, spatial correlation, and random variation. Soil CO2 efflux was measured in a wheat (Triticum aestivum L.) field at two different dates with differing soil water contents, and soil plus vegetative CO2 efflux was measured at three grassland sites. Carbon dioxide efflux was determined by the alkali absorption method using static chambers located at 3‐m intervals within a 18 m by 18 m square grid. Positional trends were identified using a multiple regression technique, and with a t‐test extended into two dimensions. Data were detrended using a generalized least squares (GLS) regression procedure. Semivariograms were used for analysis of spatial correlation and random variability. The assumption of spatial homogeneity (first‐order stationarity) was not founded for CO2 efflux for four of the five data sets. Positional trends accounted for 16 to 48% of the total variability in these cases. Spatial correlation was not detected, although ignoring positional trends may well have resulted in the opposite conclusion. Spatial structure was affected by the soil water content under wheat. Defining the spatial structure of soil respiration requires determinations under a range of environmental conditions. Advantages of the trend identification and quantification procedures utilized are direct application of common regression techniques, direct evaluation of first‐order stationarity following trend removal and correction for correlated error structure.
Propanil: Toxicological Characteristics, Metabolism, and Biodegradation Potential in Soil
Authors: Pothuluri Jairaj V. , Hinson Jack A. , Cerniglia Carl E. 
Published: July 2010

AbstractPropanil [3′,4′‐dichloropropionanilide (DCPA)] is a biologically active pollutant. Propanil is extensively used around the world for control of weeds in rice (Oryza sativa L.) production. Although propunil by itself is of low toxicity, the highly toxic impurities 3,3′,4,4′‐tetrachloroazobenzene (TCAB) and 3,3′,4,4′‐tetrachloroazoxybenzene (TCAOB) from the manufacture of 3,4‐dichloroaniline (DCA) often contaminate the 3,4‐DCA‐derived herbicide propanil. These componnds are approximately isosteric to 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), and acting at the Ah receptor, are toxic by mechanisms similar to those of TCDD. Both TCAB and TCAOB are cytotoxic, embryolethal, and teratogenic, and hence are classified as possible human genotoxins. In soil, biodegradation of propanil liberates DCA, which is converted by microbial peroxidases to TCAB and other azo products. The TCAB and TCAOB may accumulate in rice‐growing soils, and leach into groundwater. The toxicity and fate of these compounds in the environment and the ability of microorganisms to detoxify them are discussed.
An Evaluation of Nitrogen Mineralization Indices for Organic Residues
Authors: Douglas B.F. , Magdoff F.R. 
Published: July 2010

AbstractOrganic residues without high levels of toxic metal or organic constituents are usually applied to agricultural soils at rates based on assumed contributions of available N to the growing crop. However, there is no accepted test for assessing potential available N supply from residues. Although the actual contribution will depend on soil characteristics and climate as well as residue characteristics, a chemical index might be useful in ranking residues according to potential available N contributions. An experiment was conducted to evaluate a number of chemical indices for N availability. The 19 residues used in the study consisted of seven types of manures, six sewage sludges, and six composted or mixed soil amendments. Organic residues were mixed with sandy top‐soil and perlite and incubated in glass tubes in the laboratory for 67 d. Total N, total Kjeldahl N, organic N, and N released into the Walkely‐Black acid‐dichromate digest (WBN) were significantly correlated with the amount of N mineralized as well as the fraction of organic N mineralized during the incubation. The best relationship for the amount of N mineralized was with WBN (r2 = 0.89 for a quadratic relationship). The strongest of the correlations for fraction of organic N mineralized was also with WBN (r2 = 0.82).
Transport and Prediction of Sulfate in Agricultural Runoff
Authors: Sharpley Andrew N. , Smith S. J. , Jones O. R. , Berg W. A. , Coleman G. A. 
Published: July 2010

AbstractThe measurement and simulation of sulfate‐S (SO4‐S) mobility in agricultural watersheds is necessary to evaluate the effect of management practices on associated crop S deficiencies, enhanced leaching loss of nutrient cations, and acidification of percolation waters. The concentrations and amounts of SO4‐S in runoff from six grassed and 13 cropped watersheds in the Southern Plains were, thus, measared over a 4‐yr period. Sulfate‐S transport in runoff was predicted using an equation describing the kinetics of SO4‐S desorption from soil and compared with measured values. No SO4‐S was added to any of the watersheds directly as S fertilizer or indirectly in N or P fertilizer material. No difference (at 5% level) in SO4‐S concentration in runoff from grassed (mean annual value of 12.6 mg L−1) and cropped (mean annual value of 11.0 mg L−1) watersheds was observed. Differences in amounts (0.2–18.9 kg ha−1 yr−1) were a function of runoff volume as influenced by land management. A general trend of increasing SO4‐S concentration in runoff with decreasing pH was observed, which may be a function of S dry deposition and soil and crop conditions. Measured and predicted SO4‐S concentrations in runoff for individual events were not significantly different (at 5% level), with an average predictive standard error of 1.6 mg L−1 for all watersheds, representing 17% of the measured concentration. The equation may, thus, provide a predictive tool in agronomic and environmental studies of SO4‐S movement in agricultural watersheds.
Chemical Composition of Ochreous Precipitates from Ohio Coal Mine Drainage
Authors: Winland R. L. , Traina S. J. , Bigham J. M. 
Published: July 2010

AbstractOchreous precipitates and associated solutions were collected from waters draining abandoned coal works at 28 locations in eastern Ohio. Major and trace element contents of the precipitates were determined, and comparisons were made with source solutions to evaluate the effects of pH, organic C, and ionic strength on solid‐phase composition and trace metal distribution. The pH and calcalated ionic strength of the effluents ranged from 2.6 to 7.8 and 6 to 106 mmol L−1, respectively. Associated precipitates consisted primarily of poorly crystallized oxides and oxyhydroxides of Fe with jarosite occuring as a major constituent of only one specimen. Mean Fe, SO4, Al, and Si contents of the precipitates were 8.7, 1.34, 1.11, and 0.25 tool kg−1, respectively. Silicon content increased with increasing pH of the source solution suggesting pH‐dependent adsorption. In contrast, SO4 and Al appeared to be influenced both by precipitation and adsorption reactions. Partition coefficients for As, B, Ba, Co, Cu, Cr, Mn, P, and Zn showed a preferential accumulation of all elements by the solid phase with mean log Kd values ranging from 2.9 for Cu to 6.3 for As. Manganese, Co, and Zn all showed increased partitioning into the solid phase with increasing pH and decreasing ionic strength of the drainage waters. Copper appeared to be strongly associated with organic matter, and a weaker but positive relationship was also observed with Co and Zn. No effects of pH, ionic strength, or organic C were observed for any other trace elements. Solubility equilibrium calculations suggested that the solid phase concentrations of Co, Cr, Cu, Mn, Zn, and As were primarily controlled by adsorption and/or coprecipitation phenomena whereas Ba and P activities in solution exceeded the solubilities of barite and strengite, respectively.
A Branch Exposure Chamber for Fumigating Ponderosa Pine to Atmospheric Pollution
Authors: Houpis James L. J. , Costella Mark P. , Cowles S. 
Published: July 2010

AbstractThe investigation of the effects of atmospheric pollution on metabolism and growth of woody species has long been hampered by the very difficult task of exposing mature individuals to controlled environments of air pollutants. This paper describes the design, construction, and testing of an alternative tool to whole‐tree enclosures for measuring pollution response in mature woody tissue. The chamber is a new design, though not a new concept, and is referred to as a branch exposure chamber. Designed primarily for ozone and acid precipitation exposures (and used additionally for CO2 measurements), the branch exposure chamber incorporates four major parts: support structure, fan‐air supply unit, charcoal filter unit, and exposure chamber. The exposure chamber is a 1.5‐m long by 0.7‐m diam. cylinder. The chamber is constructed of Teflon sheeting stretched over an aluminum frame; the aluminum frame is totally wrapped with nonreactive, aluminum‐backed Teflon tape. Three zones in the chamber affect exposure of the experimental tissue: an initial buffer region for mixing, a main exposure region, and an exhaust frustrum. Aerodynamic testing of the chamber‐mixing characteristics show that mixing is uniform and complete within the main exposure region. Thermal buildup within the chamber was a maximum of 3 °C under a wide range of ambient meteorological conditions. Based on current field trials of the chamber, material deterioration due to environmental variables (e.g., ultraviolet radiation, heat oxidants), is not expected to affect operation of the chamber for 24 mo. The BEC is inexpensive to build and operate, and represents a viable alternative to a whole‐tree chamber.
Trough Versus Funnel Collectors for Measuring Throughfall Volumes
Authors: Reynolds B. , Neal C. 
Published: July 2010

AbstractThroughfall was collected, at fortnightly intervals, for 1 yr beneath mature stands of Sitka spruce [Picea sitchensis (Bong.) Carr.] and Japanese larch [Larix kaempferi (Lamb.) Carr.] using arrays of troughs and funnels. There was no statistically significant difference between the annual total amounts of throughfall collected by the troughs and the funnels. Analysis of the fortnightly data revealed a small bias toward a lower catch by the troughs, although for any given fortnight, quite large differences might occur. Discussion of the results in relation to a recent paper by Kostelnik et al. concludes that there is insufficient evidence on which to reject funnels in favor of troughs for throughfall studies.
Runoff and Sediment Losses from Tall Fescue under Simulated Rainfall
Authors: Gross C. M. , Angle J. S. , Hill R. L. , Welterlen M. S. 
Published: July 2010

AbstractA study was initiated to examine runoff volume and sediment loss from various density tall fescue (Festuca arundinacea Schreb.) turf stands. Plots were established with seeding rates of 0, 98, 244, 390 and 488 kg ha−1 and allowed to mature for 9 months. Three different rainfall intensities (76, 94, and 120 mm h−1) were applied to the plots using a variable intensity rainfall simulator. Results indicate that there were significant differences in runoff volume and sediment load as affected by rainfall intensity. The runoff initiation time for the 0 kg ha−1 seeding rate was the only seeding rate that was significantly different from all others. Mean runoff rates over time were significantly different for the first 5‐min time interval of the 30‐min storm for all three intensities. There was a significant difference in total sediment load for all three rainfall intensities. At the high (120 mm h−1) rainfall intensity, there was over a sixfold reduction in sediment loss when comparing the 0 kg ha−1 seeding rate to the 98 kg ha−1 seeding rate. Greater sediment loss reductions were observed at the lower rainfall intensifies when comparing the same seeding rates. Sediment loss rates did not differ for the 98, 244, 390, and 488 kg ha−1 seeding rates at the low (76 mm h−1) and medium (94 mm h−1) rainfall intensities. At the high (120 mm h−1) rainfall intensity, significant differences were detected between the 0 kg ha−1 and the 488 kg ha−1 seeding rate. The 98, 244, and 390 kg ha−1 seeding rates were not statistically different at this intensity. These results indicate that even low density turfgruss stands significantly reduce sediment loss.
Sorbed Chemical Transport in Overland Flow: II. Enrichment Ratio Variation with Erosion Processes
Authors: Ghadiri H. , Rose C.W. 
Published: July 2010

AbstractBreakdown of soil aggregates by rainfall, loss of sediment, and the enrichment of fine particles, organic matter, and N in eroded sediment were measured in flume experiments with a constant rainfall rate of 100 mm h−1. Experiments covering two soil types with different soil surface configurations and slopes were designed to ensure beth exclusion of runoff entrainment as a major erosion factor, and that throughout exposure to rainfall the soil surface was unprotected by any significant depth of water. Sediment concentration differed initially for different experimental configurations, but all approached a single value after equilibrium was attained. Slope length did not have any effect on sediment concentration when rainfall was the only erosive agent at work and no surface rilling occurred. A rainfall‐induced mechanism of transient microrilling has been proposed for sediment transport when there is no significant depth of water or rills under rainfall. Aggregate size distribution of the eroded sediment was drastically different to that of the original soil. The percentage of fine particles in the eroded sediment was more than 50% of the total, while this size fraction constituted less than 5% of the original soil. The proportion of large aggregates in the eroded sediment was less than in the original soil, and the intermediate size fractions remained unchanged. This dramatic production of fine particles is due to direct raindrop impact on the exposed surfaces of soil aggregates. The resulting loss of fine sediment from large aggregates has been termed raindrop stripping, a process that can lead to significant enrichment of any sorbed chemical concentrated in the outer layers of soil aggregates. The peeling action of raindrops was shown to be responsible for the formation of the bulk of fine particles found in eroded sediment. This mechanism, together with the differential concentration of sorbed chemicals within the aggregates, were found to be the main cause of the enrichment of sorbed chemicals in the eroded sediment. The enrichment ratio of organic C and N beth decreased with cumulative soil loss and duration of the erosion event.
Radiocesium Levels in Swedish Moose in Relation to Deposition, Diet, and Age
Authors: Palo R. T. , Nelin P. , Nylen T. , Wickman G. 
Published: July 2010

AbstractDuring the hunting season in September 1986 in Västerbotten, Sweden, the mean concentration of 137 Cs in muscle tissue of moose [Alces alces (L.)] was 500 Bq kg−1 (SD = 400) (median = 398) fresh weight in calves, and 300 Bq kg−1 (SD = 250) (median = 253) in adults. In September 1987, the median concentration in calves was 401 Bq kg−1 and 201 Bq kg−1 in adults. In September 1988 the mean concentration of 137 Cs was 1300 Bq kg−1 (SD = 1000) (median = 930) in calves, and 640 Bq kg−1 (SD = 520) (median = 499) in adults. Calves contained about 40% higher activity concentration than adults. A positive correlation between muscle activity and deposition per square meter was evident. Concentration in typical food plants for moose such as bilberry (Vaccinium myrtillus L.) peaked at 2000 Bq kg−1 (SD = 1000) in July 1986 but had declined to about 600 Bq kg−1 (SD = 200) by July 1988. However, in birch (Betula pubescens Ehrh.) the activity concentration did not differ between 1986, 1987 and 1988. Rumen content analyses showed that in 1988, utilization of lingonberry (Vaccinium vitis‐idaea) increased while the proportion of willow (Salix spp.) decreased. No relationship between the proportion of specific plant species in the rumen and flesh activity concentration was noted. An increase in foraging on highly contaminated plant species such as bilberry, aquatic plants and mushrooms in July and August 1988 might explain the rise in concentration in moose in September. Diet selection by animals is an important factor in predicting the uptake of environmental contaminants and the changes in tissue levels of such contaminants with time.