bluuebunny/crossref_metadata_2025 huggingface dataset:
Tillage and Crop Influences on Physical Properties for an Epiaqualf
Authors: Blanco-Canqui Humberto , Gantzer C. J. , Anderson S. H. , Alberts E. E.
Published: January 2014

Tillage impacts on soil properties differ among soils. This study investigated tillage, cropping, and wheel traffic (WT) effects of 13‐yr of no‐tillage (NT), chisel plow (CP), and moldboard plow (MP) under continuous corn (Zea maysL.) and soybean (Glycine maxL.) including a check treatment of continuous cultivated fallow (CCF) on bulk density (ρb), organic matter (OM), soil–water retention, and saturated hydraulic conductivity (Ksat) on a Mexico silt loam (fine, smectitic, mesic, Aeric Vertic Epiaqualf). Possible relationships between runoff and effectiveKsat(Keff) were also studied. Soil properties were determined on intact cores of 76‐mm diam. collected from trafficked and nontrafficked positions for the 0‐ to 100‐mm and 100‐ to 200‐mm depths from the Midwest Research Claypan Farm erosion plots near Kingdom City, MO. Results show that the CCF had lower ρb, OM,Ksat, and higher surface runoff than other treatments (P< 0.01). Tillage effects on soil properties among NT, CP, and MP were small and crop dependent. Corn had lowerKsat(7.3 mm h−1) than soybean (11.7 mm h−1;P< 0.01). Conversely, corn had slightly higher ρb(1.53 Mg m−3) than soybean (1.48 Mg m−3;P< 0.01). The ρbincreased from 1.47 to 1.52 Mg m−3and OM decreased from 15.5 to 14.0 g kg−1with depth (P< 0.01). Wheel traffic reducedKsatby three times and increased ρbby 6% (P< 0.01). Bulk density was a significant predictor of logKsat(P< 0.01) but not for soils under CCF management. TheKeffwas not related to runoff with the exception of the CCF treatment, which had slightly more runoff and lowerKeff(P< 0.05). Overall, tillage treatments had no significant effects on soil properties; however, cropping and WT had small significant effects on ρbandKsat
Impact of Banded Potassium on Crop Yield and Soil Potassium in Ridge‐Till Planting
Authors: Rehm G. W. , Lamb J. A.
Published: January 2014

Adequate application of fertilizer K has been identified as a key management practice needed to achieve optimum production in a ridge‐till planting system. However, the impact of K fertilization frequency has not been documented. Additionally, banded application of K also raises questions about the correct procedure to be followed for collection of soil samples. This study was conducted in the fields of three farmers who used the ridge‐till planting system for corn (Zea mays L.) and soybean (Glycine max L.) grown in rotation. Potassium was applied in a subsurface band in the center of existing ridges in the fall of Year 1 before corn and Year 2 before soybean at rates of 0, 18.5, 37.0, 55.5, and 74.0 kg ha−1 To measure the effect of residual K on soybean yield, the rates were doubled and applied only once (before Year 1). Grain yield of both corn and soybean at all sites was not affected by K application. Potassium uptake by young corn plants was increased by K rate, but uptake was not related to yield. Potassium use had no significant effect on K concentration in the most recently matured soybean trifoliate leaves sampled at early bloom. At two sites, banded K produced changes in soil test K to a depth of 15.0 cm at a distance to 15.0 cm from the row.
Dynamics of Pig Slurry Nitrogen in Soil and Plant as Determined with15N
Authors: Chantigny Martin H. , Angers Denis A. , Morvan Thierry , Pomar Candido
Published: January 2014

The fate of pig (Sus scrofa) slurry labeled with15N was investigated when applied on a clay soil (fine, mixed, frigid, Typic Humaquept) and a sandy loam (loamy, mixed, frigid, Typic Dystrochrept) cropped to maize (Zea maysL.) in 2000 and to barley (Hordeum vulgareL.) in 2001. The slurry was applied in spring 2000, and plant and soil samples were collected at 6 h (Day 1) and at Days 14, 42, 96, and 413 after application. The samples were analyzed for15N content in plant, in whole soil, and in soil NH4+–N, NO3−–N, organic N, and clay‐fixed N pools. Percentage15N recovery was >93% in both soils at Day 1 and decreased slowly thereafter. Rapid clay fixation of slurry15N occurred at Day 1, and was greater in the clay soil (34% of applied15N) than in the sandy loam (11%). At Day 96, less of the applied slurry15N was recovered in maize grown on the clay soil (29%), as compared with the sandy loam (50%). At the same period, the residual soil15N was mostly present as organic N and NO3−–N in the sandy loam, and as organic and clay‐fixed N in the clay soil. At Day 413,15N recovery in barley was about 3% of the initially applied N in both soils. The15N recovery was generally higher in the clay soil than in the sandy loam, but total15N recovery from the soil–plant system was similar for both soils. We conclude that soil type had little influence on the total15N recovery from the soil–plant system, but significantly influenced the fate of slurry N in the various soil pools and plant N uptake on the year of application.
A Simplified Falling‐Head Technique for Rapid Determination of Field‐Saturated Hydraulic Conductivity
Authors: Bagarello V. , Iovino M. , Elrick D.
Published: January 2014

Simplified measurements of the field‐saturated hydraulic conductivity, Kfs, require short duration experiments, small water volumes, and easily transportable equipment. A simplified falling‐head (SFH) technique for the rapid determination of Kfs has been developed and tested. The technique consists in applying a small volume of water on a soil surface, confined by a ring inserted a short distance into the soil, and then measuring the time from the application of water to the instant at which the surface area is no longer covered by water. A measurement of the initial and field‐saturated soil water contents, and an estimate of the α* parameter of the Gardner's exponential model are then used to calculate Kfs using a simple solution that includes gravity. The Kfs of both repacked and undisturbed soil cores was determined in the laboratory by the SFH and the early time constant‐head (ECH) techniques. The SFH and (constant‐head) pressure infiltrometer (PI) techniques were then compared in the field. The maximum discrepancy between the mean Kfs results obtained within an experiment was of a factor of approximately two. This difference is negligible in most practical applications and it was concluded that the SFH technique compared favorably with the ECH technique in the laboratory and to the PI technique in the field. The SFH technique appears promising for determining Kfs in a relatively short period of time without the need for extensive instrumentation or analytical methodology, and therefore it appears suitable for detailed field measurements over large areas.
A Simple Method for Estimating Water Diffusivity of Unsaturated Soils
Authors: Wang Quanjiu , Shao Mingan , Horton Robert
Published: January 2014

Numerical models have been extensively used for predicting water and solute transport in saturated and unsaturated soils. Soil hydraulic properties are required for quantitatively describing water and chemical transport processes in soils by the numerical models. Soil water diffusivity is one of the important hydraulic properties. Several approaches have been developed to estimate the soil water diffusivity, however the intensive calculations and time‐consuming measurements required by the methods for determining soil water diffusivity limit the application of the methods. It is necessary to develop a method with easily performed experiments for determining soil water diffusivity. In this paper, the problem of water absorption into a horizontal soil column is solved, and the relationship between cumulative infiltration and infiltration rate with the distance of the wetting front are obtained. Based on the relationships, a new and relatively simple method for estimating soil water diffusivity is presented in this paper. Experiments of water absorption into 60‐cm long and 25‐cm long horizontal soil columns were conducted to evaluate the method. Estimates of soil water diffusivity by the new method were in good agreement with estimates by the Bruce and Klute method. With the new method short (approximately 8 cm) soil columns can be used, and it is possible to use the new method to estimate soil water diffusivity of undisturbed soils. Therefore, the present method provides simplicity for determining soil water diffusivity.
Aggregate‐Size Stability Distribution and Soil Stability
Authors: Márquez C. O. , Garcia V. J. , Cambardella C. A. , Schultz R. C. , Isenhart T. M.
Published: January 2014

A new theoretical and experimental framework that permits an accurate determination of aggregate‐size stability distribution is presented. The size‐stability distribution in addition to estimating aggregate‐size distribution distinguishes between amounts of stable and unstable macroaggregates (>250 μm). The determination of aggregate‐size stability distribution involves the assumptions that soil aggregates can be categorized in terms of their size and water stability (slaking resistance). Experimentally this procedure involves the slaked and capillary‐wetted pretreatments; and a subsequent slaking treatment of aggregates >250 μm in size. We also propose the stable aggregates index (SAI) and the stable macroaggregates index (SMaI) for studying soil stability based on aggregate resistance to slaking. These indices account for the total weighted average of stable aggregates and the total weighted average of stable macroaggregates, respectively. Both the SAI and the SMaI indices were shown to be sensitive to the effects of vegetation on soil stability under different riparian buffer communities. The SAI and the SMaI indices were higher in surface soils under cool‐season grass than any of the other treatments. These soils samples are well aggregated with SAI = 74% and SMaI = 56% followed by SAI = 55% and SMaI = 37% under existing riparian forest, SAI = 40% and SMaI = 21% under 7‐yr switchgrass and SAI = 36% and SMaI = 18% under cropped system.
Critical Evaluation of the Use of Laser Diffraction for Particle‐Size Distribution Analysis
Authors: Eshel G. , Levy G. J. , Mingelgrin U. , Singer M. J.
Published: January 2014

Determination of soil particle‐size distribution (PSD) by sieving, hydrometer, and pipette methods as well as by laser diffraction (LD) suffers from inherent flaws, mainly due to the difficulty in defining the size of irregularly shaped particles. Therefore these methods yield only estimates of PSD. The objective of this study was to determine whether a functional relationship exists between the PSDs obtained by the combined sieve‐pipette method and those obtained by LD. Samples from 42 California soils were analyzed. For the LD measurements a Beckman–Coulter LS‐230 apparatus with a 750‐nm laser beam that measures particles in the range of 0.04 to 2000 μm was used, employing the Mie theory for the PSD calculations. Values of 1.5 and 0.2 for the real part and the imaginary term of the refractive index (RI), respectively, gave satisfactory results for the optical model calculations. Volume percentage of the clay‐size fraction obtained by LD was generally lower than mass percentage of the clay fraction derived by the pipette method. The opposite trend was noted for the silt‐size fraction. Coefficients of determination for the regression equations for the clay, silt, and sand fractions determined by the two methods were 0.702, 0.689, and 0.821, respectively. Good agreement between measured and calculated LD values for one size class was accompanied by poor agreement between measured and calculated values for the other. The LD method provides a continuous PSD curve, which enables a detailed data analysis and a flexible application of different particle‐size dependent classification systems.
New Method for Determining Water‐Conducting Macro‐ and Mesoporosity from Tension Infiltrometer
Authors: Bodhinayake Waduwawatte , Si Bing Cheng , Xiao Chijin
Published: January 2014

Characterization of water‐conducting porosity at and near saturation is required in understanding rainfall and snowmelt infiltration and runoff as well as chemical transport in soil. There are methods available to quantify water‐conducting porosity in situ, but with serious limitations. The objective of this paper was to present a general equation for water‐conducting porosity based on ponded‐ and tension‐infiltration measurements. Some analytical solutions are developed for specific unsaturated hydraulic conductivity functions such as the Gardner's exponential and rational power models, Brooks and Corey model, and van Genuchten–Mualem model. Tension infiltrometer measurements were taken at six different pressure heads between −0.3 to −2.2 kPa and double‐ring infiltrometer measurements at a pressure head of 0.35 kPa. The analytical solutions were compared with numerical solutions and existing methods for calculation of water‐conducting porosity. Both the analytical and numerical solutions can reliably determine the water‐conducting porosity of surface soils in situ within the practical pressure head range of the tension infiltrometer. Our method gave consistent water‐conducting porosity, regardless of the width of pressure head ranges. The existing methods overestimated water‐conducting macroporosity by a factor of greater than two and overestimated total water‐conducting porosity by a factor of >10 for measurements taken at large pressure head intervals compared with that of our method. Combining with hydraulic parameter estimation from tension infiltrometer measurements, our method may reduce the number of tension infiltration measurements required to calculate water‐conducting porosity.
Calibration of Capacitance Probe Sensors in a Saline Silty Clay Soil
Authors: Kelleners T. J. , Soppe R. W. O. , Ayars J. E. , Skaggs T. H.
Published: January 2014

Capacitance probe sensors are a popular electromagnetic method of measuring soil water content. However, there is concern about the influence of soil salinity on the sensor readings. In this study capacitance sensors are calibrated for a saline silty clay soil. An electric circuit model is used to relate the sensor's resonant frequency F to the permittivity (ε) of the soil. The circuit model is able to account for the effect of dielectric losses on the resonant frequency. Dielectric mixing models and empirical models are used to relate the permittivity to the soil water content (θ). The results show that the electric circuit model does not fit the F–ε(θ) data if the calibrated bulk electrical conductivity (EC) model is used. The dielectric losses are overestimated. Increasing the exponent c in the tortuosity factor of the bulk EC model and thereby lowering the bulk EC and the dielectric losses improves the performance of the model. Measured and calculated volumetric water contents compare reasonably well (R2 = 0.884). However, only 73 out of 88 data points can be described. The rejected points are invariably at high water contents where the high dielectric losses result in the sensor frequency being insensitive to ε(θ).
Relations between Soil and Tree Stem Water Content and Bulk Electrical Conductivity under Salinizing Irrigation
Authors: Nadler Arie
Published: January 2014

In a semiarid region in a grapefruit (Nucellar ‘Marsh seedless, Citrus paradise Macf.) orchard irrigated with salinized waters, the water content (θ) and bulk electrical conductivity (σa) of the trees’ stems and the root‐zone soil was monitored by time domain reflectometry (TDR) and electrical conductivity meter for a year. For the purpose of irrigation scheduling the objective was to verify correlations between (i) stem and soil θ and (ii) stem and soil σ. Measured θsoil and σa, soil were in good agreement with the irrigation treatments, peaking in summer and decreasing during autumn. Only a weak correlation between stem's σa and θ and the soil's parameters was found and attributed to time after installation of probes in the stem; the higher σa, stem (5–10 × 10−2 dS m−1), measured up to three months after installation, were accredited to the salt content of ruptured stem cells. After curing of the installation wound the insulating effect of the cells' membranes may explain the lower σa, stem (2–5 × 10−2 dS m−1) measured 3 to 12 mo after installation. Periods of θsoil increase (day of year [DOY] = 80–200, and 200–280) observed by the soil probes indicated surplus irrigation. Presently the rate, intensity, and variability of the grapefruit stem reaction to soil water status and salinity leaves the soil parameters as better indicators for accurate irrigation scheduling.
ANALYTICAL SOIL–TEMPERATURE MODEL
Authors: Elias Elimoel A. , Cichota Rogerio , Torriani Hugo H. , de Jong van Lier Quirijn
Published: January 2014

The exponential‐sinusoidal one‐dimensional analytical model reasonably describes soil temperature profile. Surface temperature may be represented by the sum of two sinusoids, one related to annual and the other to daily temperature variations, each one having constant amplitude. We introduce here a correction for the temporal variation of daily amplitude, and demonstrate that the heat equation can still be solved analytically. We compared temperature predictions obtained from the novel and from the usual analytical solution, using the root mean squared error (RMSE). For individual days, at a depth z = 0.10 m, the maximum value was RMSE = 0.30°C; for whole months, the maximum value was RMSE = 0.29°C, and the minimum was RMSE = 0.06°C. The only additional information required to apply our novel equation is information on temporal variation of daily amplitude, so we suggest our equation should be preferred when such data are readily available.
Predicting Boron Adsorption Isotherms by Midwestern Soils using the Constant Capacitance Model
Authors: Goldberg Sabine , Suarez Donald L. , Basta Nicholas T. , Lesch Scott M.
Published: January 2014

Prediction of B adsorption and transport has required detailed studies of B adsorption and subsequent determination of model parameters. In this study we tested a general regression model previously developed for predicting soil B surface complexation constants from easily measured soil chemical characteristics. The constant capacitance model, a chemical surface complexation model, was applied to B adsorption isotherms on 22 soils from the A and B horizons of 16 soil series from Oklahoma and Iowa. The measured chemical properties were surface area, organic C (OC) content, inorganic C (IOC) content, and Al oxide content. The prediction equations of Goldberg et al. (2000) were used to obtain constant capacitance model values for B surface complexation constants thereby providing a completely independent evaluation of the ability of the constant capacitance model to describe B adsorption. The model was well able to predict B adsorption isotherms on the majority of the soils. The regression model was used to obtain the parameters for the constant capacitance model. Then the constant capacitance model was used to predict the soil specific B adsorption. This is in contrast to regression models that fit adsorption of a series of soils. The distinction is that using the combined regression equations and the constant capacitance model only soil properties and not adsorption are needed to predict soil specific B adsorption data. The prediction equations developed from a set of soils primarily from California, were able to predict B adsorption on a set of soils from different parts of the country. This result suggests wide applicability of the model prediction equations developed previously, for describing B adsorption both as a function of solution B concentration and solution pH.
Identification of scyllo‐Inositol Phosphates in Soil by Solution Phosphorus‐31 Nuclear Magnetic Resonance Spectroscopy
Authors: Turner Benjamin L. , Richardson Alan E.
Published: January 2014

A large proportion of the organic P in soils can occur as scyllo‐inositol phosphates. These compounds are rarely detected elsewhere in nature and remain poorly understood, partly because conventional procedures for their determination are lengthy and erroneous. We report a straightforward procedure for the determination of scyllo‐inositol phosphates in soil extracts using solution 31P nuclear magnetic resonance (NMR) spectroscopy. Solution 31P NMR chemical shifts of a range of synthetic scyllo‐inositol phosphate esters were determined in alkaline solution. Of these, only the signal corresponding to scyllo‐inositol hexakisphosphate at approximately 4.2 ppm was identified in soil NaOH–EDTA extracts, constituting between 6.5 and 9.8% of the NaOH–EDTA extracted P. This signal has been previously assigned to choline phosphate, but we confirmed it to be an inositol phosphate using hypobromite oxidation, a procedure that destroys all organic matter except inositol phosphates. Lower order scyllo‐inositol phosphate esters were not identified in the extracts studied here, and literature reports suggest that they probably occur in insufficient concentrations to be detected by this procedure. The identification of scyllo‐inositol hexakisphosphate in soils and other environmental samples will allow its quantification in a range of environments, and facilitate research into the origins and function of this enigmatic compound.
Evaluation of Adsorbed Arsenic and Potential Contribution to Shallow Groundwater in Tulare Lake Bed Area, Tulare Basin, California
Authors: Gao S. , Fujii R. , Chalmers A. T. , Tanji K. K.
Published: January 2014

Elevated As concentrations in shallow groundwater in parts of the Tulare Basin, California, are a concern because of potential migration into deeper aquifers that could serve as a source of future drinking water. The objectives of this study were to evaluate adsorbed As and the potential contribution to groundwater using (i) isotopic dilution, (ii) successive extraction with an electrolyte solution resembling the pore‐water chemical composition, and (iii) PO4exchange for As. Sediment samples collected from 2 to 4 m below land surface in the Tulare Lake bed area contained a total As concentration of 24 mg As kg−1Pore water extracted under hydraulic pressure contained a total As concentration of 590 μg As L−1, which predominantly contained As as arsenate [As(V), 97%], a minor amount of arsenite [As(III), 3%], and non‐detectable organic As. The isotopic dilution method [73As(V)] estimated that the concentration of adsorbed As(V) on the sediment was 5.7 mg As kg−1at pH 8.5 and 6.7 mg As kg−1at pH 7.5, respectively. Fourteen successive 24‐h extractions with the artificial pore water released up to 57 to 61% of the adsorbed As(V) that was determined by isotopic dilution, indicating that only a portion of the adsorbed As could be released to groundwater. The phosphate‐exchangeable As (0.1MPO4, pH 8.5 or 7.5) was 63% of the isotopically exchangeable As(V). Thus, extraction of As by 0.1MPO4at ambient pHs is recommended as a method to determine the potential amount of As(V) on sediments that could be released to the solution phase. The overall results indicated that adsorbed As could be a significant source of As to groundwater. However, other factors that affect As transport such as the leaching rate need to be considered.
Surface Runoff along Two Agricultural Hillslopes with Contrasting Soils
Authors: Needelman Brian A. , Gburek William J. , Petersen Gary W. , Sharpley Andrew N. , Kleinman Peter J. A.
Published: January 2014

The targeting of critical surface runoff‐producing zones should account for the influence of subsurface soil characteristics. In this study we assessed the runoff response of contrasting colluvial and residual soils. The study was conducted along two hillslopes within a 39.5‐ha mixed land use watershed in Pennsylvania. Six sites (four colluvial, two residual) were monitored for runoff, hydraulic head, water table depth, and soil water content. A total of 111 rainfall events were monitored during the periods of July to December 2000, April to December 2001, and April to December 2002. Two high‐intensity (5‐min peak > 8 cm h−1) events had return periods of 2.5 and 4 yr. The colluvial soils are somewhat poorly and moderately well drained with fragipans and high clay content (37–44%) argillic horizons (fine, mixed, semiactive, mesic Aquic Fragiudalfs); the residual soils are well drained with moderate clay content (24%) argillic horizons (fine‐loamy, mixed, semiactive, mesic Typic Hapludults). Across all events, overall runoff yields averaged 2.4% from the four colluvial sites and 0.01% from the two residual sites. The two colluvial sites with the greatest runoff production were located at the base of a primarily colluvial hillslope. The largest events at these sites occurred during periods of surface saturation (soil surface to a depth of at least 30 cm). These results suggest that nonwinter P management for these residual soils should focus on rare, large events. Nutrient management planning could be improved if runoff estimation methods were to better integrate information on subsurface and upslope soil hydrologic properties.
Organic Matter and Aggregate Size Interactions in Infiltration, Seal Formation, and Soil Loss
Authors: Lado M. , Paz A. , Ben-Hur M.
Published: January 2014

The objectives of this study were to investigate (i) the effect of soil organic matter (OM) content on the mechanisms that form a seal, and (ii) the OM content and aggregate size interactions in seal properties, infiltration rate (IR), and soil loss. Two samples of sandy loam (Humic Dystrudept) designated low‐OM soil (2.3% by weight OM) and high‐OM soil (3.5% OM) were studied. Aggregate sizes <2, 2 to 4, and 4 to 6 mm of each soil were exposed to 80 mm of simulated rainfall with an intensity of 42 mm h−1 The final IR increased with increasing aggregate size from 4.2 to 5.2 mm h−1 in the low‐OM soil, and from 5.8 to 10.8 mm h−1 in the high‐OM soil. There was a significant interaction between OM content and aggregate size in seal formation and final IR. The low aggregate stability and the high dispersivity of the low‐OM soil allowed the development of a dense and thick crust for all the aggregate sizes. Conversely, the high aggregate stability and the low dispersivity of the high‐OM soil limited the seal formation. Consequently, the IR values were high and differences in IR among the three aggregate sizes in this soil were relatively high. The soil losses increased with increasing aggregate size, ranging from 4.5 × 10−3 to 6.6 × 10−3 kg m−2 mm−1 in the low‐OM soil, and from 1.2 to 3.8 × 10−3 kg m−2 mm−1 in the high‐OM soil. In this case, no significant interaction was found between soil OM content and aggregate size.
Soil Organic Matter Fractions under Managed Pine Plantations of the Southeastern USA
Authors: Echeverría Marietta E. , Markewitz Daniel , Morris Lawrence A. , Hendrick Ronald L.
Published: January 2014

Herbicide application in plantation forests may affect soil productive capacity through its effect on the quantity and characteristics of soil C. We examined changes in surface soil (<10 cm) soil organic matter (SOM) fractions in 12‐ to 18‐yr‐old pine stands from the Lower Coastal Plain and Piedmont of the southeastern USA that were receiving complete competition control treatments (n= 13 paired plots). Light (LF) (<1.6 g cm−3), medium (MF) (1.6–2.0 g cm−3), and heavy (HF) fraction (2.0 g cm−3) SOM were isolated by density separation and the HF was hydrolyzed isolating a hydrolyzable (H‐HF) and residual fraction (R‐HF). Herbicide treated surface soils had lower whole soil C (12.8 g kg−1) and N (0.51 g kg−1) compared with untreated controls, 16.1 g C kg−1and 0.63 g N kg−1Across all sites, the greatest decreases in soil C and N occurred in the LF and MF fractions. The majority of C and N in Lower Coastal Plain surface soils (∼90% sand) is partitioned in the LF + MF, while in the Piedmont soils (∼60% sand) it is in the H‐HF. Decreases in these SOM fractions were only slightly greater than decreases in whole soil SOM. Additionally, there was a significant decrease of 27, 41, and 31% in net N mineralization (7‐d anaerobic incubation) due to treatment in a Piedmont site for whole soil (WS), WS + L/MF, and WS + HF, respectively. For the Lower Coastal Plain site, there was an 18% decrease in the WS + L/MF mixture only. Complete competition control in both the Piedmont and Coastal Plain clearly decreased SOM quantity. Decreases in SOM quality as indicated by decreased net N mineralization potential were also evident. The results suggest herbicide treatments may decrease the productive capacity of surface soils.
An efficient biotreatment process for polyvinyl alcohol containing textile wastewater
Authors: Magdum Sandip S. , Minde Gauri P. , Adhyapak Upendra S. , Kalyanraman V.
Published: January 2014

The aim of this work was to optimize the biodegradation of polyvinyl alcohol (PVA) containing actual textile wastewater for a sustainable treatment solution. The isolated microbial consortia of effective PVA degrader namely Candida Sp. and Pseudomonas Sp., which were responsible for symbiotic degradation of chemical oxidation demand (COD) and PVA from desizing wastewater. In the process optimization, the maximum aeration was essential to achieve a high degradation rate, where as stirring enhances further degradation and foam control. Batch experiments concluded with the need of 16 lpm/l and 150 rpm of air and stirring speed respectively for high rate of COD and PVA degradation. Optimized process leads to 2 days of hydraulic retention time (HRT) with 85–90% PVA degradation. Continuous study also confirmed above treatment process optimization with 85.02% of COD and 90.3% of PVA degradation of effluent with 2 days HRT. This study gives environment friendly and cost effective solution for PVA containing textile wastewater treatment.
Performance evaluation and bacteria analysis of AFB-MFC enriched with high-strength synthetic wastewater
Authors: Huang Jian-sheng , Guo Yong , Yang Ping , Li Chong-ming , Gao Hui , Feng Li , Zhang Yun
Published: January 2014

In order to study the performance and bacterial communities of an anaerobic fluidized bed microbial fuel cell (AFB-MFC) system, the 16S rDNA gene sequencing was applied, and high-strength synthetic wastewater was treated by the AFB-MFC system. The high-strength synthetic wastewater, in which the concentrations of chemical oxygen demand (COD), nitrite nitrogen, and nitrate nitrogen were above 19,000, 2,516–3,871 and 927–1,427 mg/L, was treated by the AFB-MFC system. The removal efficiency of COD, nitrite nitrogen, and nitrate nitrogen reached 70–89, 98 and 98%, while the maximum voltage was 394 mV. The bacteria analysis revealed the presence of Alistipes putredinis, Carnobacterium sp., Victivallis vadensis, Klebsiella pneumoniae, Thauera sp., Parabacteroides merdae, Parvimonas micra, Parabacteroides sp., and Desulfomicrobium baculatum in the anode chamber. In addition, the Klebsiella pneumoniae was observed to have the capability of organic degradation and electricity generation, while the Thauera sp. has the capability of denitrification.
Effect of ambient temperatures on disinfection efficiency of various sludge treatment technologies
Authors: Bauerfeld Katrin
Published: January 2014

Sewage sludge produced during municipal wastewater treatment has to be treated efficiently in order to reduce impacts on the environment and on public health. In Germany and many countries, large quantities of sludge are reused in agriculture in order to recycle nutrients and organic material. In order to quantify the effect of different ambient temperatures on conventional and advanced sludge treatment technologies as well as on disinfection efficiency, a comprehensive research study was performed at Braunschweig Institute of Technology. The detailed results show that ambient temperature has a strong effect on biological liquid sludge stabilization and on natural dewatering and drying technologies, although microbiological quality of treated sludge, indicated by Escherichia coli concentration, does not meet the requirements for unrestricted reuse in agriculture. Composting and lime treatment of sludge are most efficient on reducing E. coli, as high temperatures and high pH values arise in the material respectively.
Development of a highly specific and productive process for n-caproic acid production: applying lessons from methanogenic microbiomes
Authors: Agler M. T. , Spirito C. M. , Usack J. G. , Werner J. J. , Angenent L. T.
Published: January 2014

High productivity and specificity in anaerobic digesters arise because complex microbiomes organize into a metabolic cascade to maximize energy recovery and to utilize the advantage that the gaseous end product methane freely bubbles out of the system. These lessons were applied to ascertain whether a reactor microbiome could be shaped to produce a different end product. The liquid product n-caproic acid was chosen, which is a 6-carbon-chain carboxylic acid that is valuable and that has a relatively low maximum solubility concentration for product recovery. Acetoclastic methanogenesis was inhibited by pH control and a route was provided for n-caproic acid extraction by implementing selective, in-line recovery. Next, ethanol was supplemented to promote chain elongation, which is a pathway in which short-chain carboxylic acids are elongated sequentially into medium-chain carboxylic acids with two-carbon units derived from ethanol. The reactor microbiome developed accordingly with the terminal process catalyzed by chain-elongating bacteria. As a result, n-caproic acid production rates increased to levels comparable to anaerobic digestion systems for solid waste treatment.
Organic removal activity in biofilm and suspended biomass fractions of MBBR systems
Authors: Piculell Maria , Welander Thomas , Jönsson Karin
Published: January 2014

The moving bed biofilm reactor (MBBR) wastewater treatment process is usually designed based on the assumption that all activity in the process occurs in the biofilm on the MBBR carriers, although there is always some active biomass in the bulk liquid due to biofilm sloughing and, sometimes, free-growing bacteria. In this study the removal of organic matter is evaluated in laboratory-scale MBBR reactors under varying load, hydraulic retention time (HRT), oxygen concentration and volumetric filling degree of carriers in order to determine the heterotrophic activity in the different fractions of the MBBR biomass. The results showed that the heterotrophic conversions in an MBBR can show the same type of diffusion limited dependency on oxygen as nitrification, even for easily degradable substrates such as acetate. The contribution to the removal from the suspended biomass is shown to vary depending on HRT, as the amount of suspended solids changes. The developed method in this report is a useful tool for determining heterotrophic activity in the separate fractions of biomass in MBBRs.
Oxygen-induced dynamics of nitrous oxide in water and off-gas during the treatment of digester supernatant
Authors: Stenström F. , Tjus K. , la Cour Jansen J.
Published: January 2014

Nitrous oxide (N2O) is a potent greenhouse gas and of special concern in wastewater treatment. It is formed in biological wastewater treatment under both aerobic and anaerobic conditions. A major reason for high N2O emissions is low oxygen concentration during nitrification. In this full-scale study of N2O emissions from a sequencing batch reactor for treating digester supernatant, the oxygen concentration was reduced stepwise to investigate how N2O emissions were influenced. N2O concentrations were measured online in water and off-gas. A distinct relationship was found between low oxygen concentration and high N2O emissions. N2O was formed in water during both nitrification and denitrification. Decreased oxygen concentration during nitrification led to increased nitrite concentration, which in turn led to increased N2O concentration in the subsequent denitrification phase. When the nitrification resumed, accumulated N2O was stripped off to the atmosphere. Very high concentrations of N2O, over 56,000 ppmv, were measured in the off-gas. Furthermore, the maximum amount of N2O emitted during one cycle corresponded to 107.6% of the total nitrogen load (21.9% of total nitrogen present in the bulk liquid at the beginning of the cycle). This is among the highest emission levels ever measured from a full-scale municipal plant for digester supernatant.
Comparison of two standard odor intensity evaluation methods for odor problems in air or water
Authors: Curren Jane , Snyder Cherie L. (Cher) , Abraham Samantha , Suffet I. H. (Mel)
Published: January 2014

Government agencies responsible for ensuring healthful water and/or air quality are often faced with resolving public complaints of nuisance odors. Understanding variations in odor intensity may ultimately lead to the establishment and application by such agencies of quantitative limits for effective odorant control. An odor panel was trained in suprathreshold odor intensity evaluation using both the ASTM Method E544 (Butanol Method) and the APHA Method 2170 (Flavor Profile Analysis (FPA) Method). A linear mixed model was fitted to the panel data, taking into account the fixed effects of concentration levels and the random effects of panelists and sessions. The FPA method proved easier to administer and revealed less inter-session variance than the ASTM Method, suggesting its greater utility in applications involving odor panels. For both methods, there was a high standard deviation, relative to the mean. This finding indicates that the intensity scales may be useful for understanding relative odor intensities, but should not be used as a precise measure, or as a basis for establishing regulatory limits.
Magnetic Fe3O4@C nanoparticles as adsorbents for removal of amoxicillin from aqueous solution
Authors: Kakavandi Babak , Esrafili Ali , Mohseni-Bandpi Anoushiravan , Jonidi Jafari Ahmad , Rezaei Kalantary Roshanak
Published: January 2014

In the present study, powder activated carbon (PAC) combined with Fe3O4 magnetite nanoparticles (MNPs) were used for the preparation of magnetic composites (MNPs-PAC), which was used as an adsorbent for amoxicillin (AMX) removal. The properties of magnetic activated carbon were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunaeur, Emmett and Teller and vibrating sample magnetometer. The operational factors affecting adsorption such as pH, contact time, adsorbent dosage, initial AMX concentration and temperature were studied in detail. The high surface area and saturation magnetization for the synthesized adsorbent were found to be 671.2 m2/g and 6.94 emu/g, respectively. The equilibrium time of the adsorption process was 90 min. Studies of adsorption equilibrium and kinetic models revealed that the adsorption of AMX onto MNPs-PAC followed Freundlich and Langmuir isotherms and pseudo-second-order kinetic models. The calculated values of the thermodynamic parameters, such as ΔG°, ΔH° and ΔS° demonstrated that the AMX adsorption was endothermic and spontaneous in nature. It could be concluded that MNPs-PAC have a great potential for antibiotic removal from aquatic media.
Preferential catalytic ozonation of p-nitrophenol by molecularly imprinted Fe3O4/SiO2 core-shell magnetic composites
Authors: Yang Jiannan , Li Shuzhen , Gong Yibin , He Chun , Zhang Qiong , Wu Jinqing , Liao Weichen , Shu Dong , Tian Shuanghong
Published: January 2014

Molecularly imprinted Fe3O4/SiO2 core-shell magnetic composites (Fe3O4/SiO2-MIP) were successfully prepared via anchoring p-nitrophenol (p-NP) imprinted functional polymers on the surface of amino-modified Fe3O4/SiO2 core-shell particles. Synthesized magnetic Fe3O4/SiO2-MIP composites were characterized by X-ray diffraction, scanning electronic microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and magnetic property measurement. The preferential catalytic ozonation of p-nitrophenol was evaluated in comparison with the competitive reaction in the presence of coexistent phenol. The results showed that the prepared Fe3O4/SiO2-MIP composites exhibit strong adsorption ability due to the strong bonding between p-NP and the molecularly imprinted layer. The Fe3O4/SiO2-MIP demonstrated a preferential catalytic ozonation of p-NP by the recognition ability of the molecularly imprinted layer to the target p-NP. The enhanced catalytic activity using Fe3O4/SiO2-MIP composites could be attributed to the excellent recognition absorption of the MIP layer on the surface of Fe3O4/SiO2-MIP to p-NP.
Kinetic evaluation of chromium(VI) sorption by water lettuce (Pistia)
Authors: Chakraborty Rupa , Karmakar Sukalpa , Mukherjee Somnath , Kumar Sunil
Published: January 2014

An investigation was performed to evaluate the uptake capacity of Pistia in living condition for adsorptive removal of chromium(VI) from spiked solution for examining a remedial measure for disposal of chrome-laden wastewater in an urban wetland system. Kinetics results show about 78% removal was achieved for 3 mg/L initial concentration of Cr(VI). Experimental data showed that the root portion absorbed more Cr(VI) (28.54 μg/g) compared to accumulation in leaf (5.73 μg/g). It was also noted that the plant could effectively remove Cr(VI) from the solution with minor damage up to an initial Cr(VI) concentration of 3 mg/L, for which the adsorption isotherm studies were conducted. The maximum uptake capacity of the plant was recorded as 0.05 mg/g of Cr(VI) at the equilibrium level after a contact period of 7 days for an initial concentration of 8 mg /L, although severe physiological damage occurred. The experimental results were plotted in Langmuir and Freundlich isotherm models and both were found to be well fitted (r2 = 0.979 and r2 = 0.974 respectively). The high value of n (2.16) reveals a strong bond between the plant root and dissolved Cr(VI), which favours the adsorption process. The order of the reaction was also examined on the basis of uptake capacity and it was found that the second order model fitted best.
Review of Australian Higher Education: An Australian Policy Perspective
Authors: Montague Alan
Published: January 2014

Higher education is one of the key foundations that economic prosperity is founded upon. Government policies, funding and strategic planning require a fine balance to stimulate growth, prosperity health and well-being. The key Australian government policies influenced by a Review of Australian Higher Education report include attracting many more Australian citizens from disadvantaged backgrounds to higher education and increasing to 40% by 2020 the number of Australian people aged 25 to 34 years attaining at least a bachelor-level qualification — a challenge, given that the current level is 29%. An added key policy is the move to a student entitlement funding model that Australia introduced from 2012, with around half of the 46 recommendations being implemented by early 2013. This article undertakes research based on secondary data from extensive literature reviews to comment critically on the efficacy of the policy approached recommended by the Review of Australian Higher Education in 2008, and now being gradually implemented. Australia faces significant challenges in higher education to rebuild, redevelop, sustain and progress higher education. The domestic and global competition for talented and skilled people is becoming more crucial. Ageing populations combined with a decreasing proportion of young people, particularly within OECD countries, exacerbates the problem. Australia, among most, if not all nations, must develop many more innovative and skilled people to sustain and rejuvenate its industry and society.
Activist Academics: What Future?
Authors: Grey Sandra J.
Published: January 2014

Four decades on from the Year of the Student, when university campuses were sites of protest and dissent, it is crucial to consider how the involvement of university academics in activist causes has changed. Using social movement frameworks this article examines how organisational, political and cultural contexts have hindered social and political activism by New Zealand academics. Declining resources and increased accountability mechanisms in the tertiary education sector have intersected with a cultural context dominated by pragmatism and instrumentalism to constrain activism by academics. Despite these constraints, the author argues that it is crucial for academics to be involved in forms of day-to-day resistance and to establish ongoing connections to activist organisations in order to challenge the hegemonic narratives of marketisation and managerialism which are impacting on all parts of New Zealand society, including universities.
Biosurveillance as a Terrain of Innovation in an Era of Monopoly Finance Capital
Authors: Magnusson Jamie
Published: January 2014

Situated in a context of higher education policy, this article examines the institutionalization of ‘innovation’ as a national neoliberal economic strategy. As neoliberal capital has become increasingly financialized, this innovation strategy has come to be woven through biotechnological innovation as an economic strategy, and oriented to the politics of permanent war. Following a ‘strong-state’ thesis, relations of monopoly finance capital increasingly organize knowledge production within higher education and the need for technological innovation related to national security. The author shows that the resulting academic cultures of innovation are heavily invested in subordinating research in the areas of health and environment to military strategy in order to achieve full spectrum global systems of biosurveillance.
The Policy Delphi: A Method for Identifying Intended and Unintended Consequences of Educational Policy
Authors: Manley R. Adam
Published: January 2014

This article highlights a rarely utilized but effective technique for identifying intended and unintended consequences of past or current policy or policy change. The author guides the reader through the process of identifying potential participants, contacting participants, developing the policy Delphi instrument, and analyzing the findings by sharing an example of a research study he recently completed. In addition, the author also shares other potential uses of this methodology.
Justice for All? Special Education 2000 and the Politics of Difference
Authors: McMenamin Trish
Published: January 2014

In this article I will argue that New Zealand's Special Education 2000 (SE2000) policy demonstrates the way in which seemingly just and fair policies can lead to occurrences of injustice and unfairness towards some of those whom they impact. What this debate turns on is the justice of a policy which takes as its starting point the unquestioned premise that the educational needs of all disabled children and young people will be best served in local state-funded schools rather than in day-special schools and the legitimacy of the decisions and actions of policy makers and bureaucrats based on this premise. Drawing on Iris Marion Young's conceptions of justice and her notion of ‘oppression’ and ‘domination’ as two social conditions that define injustice, the author argues that SE2000 in its conception and enactment serves to perpetrate, rather than mitigate, injustice on some disabled children and young people and their families with respect to schooling options and choices.
Marx and Foucault: Subjectivity, Employability and the Crisis of Youth Unemployment in the Great Global Recession
Authors: Peters Michael A. , Besley Tina
Published: January 2014

This article explores the different approaches taken to the concepts of work or labour by Marx and Foucault, examining in particular the question of subjectivity in relation to youth unemployment and the current crisis of youth unemployment as part of the aftermath of the global recession of 2008.