bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Initial and Boundary Conditions on Solute Transport through Undisturbed Soil Columns
Authors: Hamlen C. J. , Kachanoski R. G.
Published: January 2014

The effect of initial soil water content (θ) and steady and transient water flow boundary conditions (Jw) on the transport of identical solute pulses was examined in four undisturbed soil columns. Solute breakthrough curves (BTCs) and θ were monitored nondestructively using time domain reflectometry (TDR). Pulse concentrations were predicted from TDR impedances (Ω) using either a steady Jw calibration or a transient Jw calibration. The steady Jw calibration, βs, was estimated from the steady Jw BTC. The transient calibration, β(θ), was estimated from the changes in Ω−1(θ) between three different calibrating solutions of Cl− (1.106, 1.503, and 1.900 g L−1) in the pore space. All β(θ) curves had a very similar decreasing curvilinear shape. At one location the β(θ) curve was high and residual water was not completely replaced by the calibrating solutions. The steady Jw calibration values were generally slightly lower than the equivalent β(θ) value, but collectively they followed a similar decreasing curvilinear trend with steady θs Solute applied to initially dry soil tended to lead the transient Jw wetting front and breakthrough began with the start of cumulative drainage. These BTCs also had the greatest amount of BTC tailing. Solute applied to initially wet soil had less BTC tailing. The least amount of BTC spreading occurred during the steady Jw condition. The two transient Jw experiments had very similar distributions of solute with depth, despite the contrasting initial conditions. The pores actively transporting solute appear to be determined by the Jw boundary condition.
Splash–Saltation of Sand due to Wind‐Driven Rain
Authors: Cornelis Wim M. , Oltenfreiter Greet , Gabriels Donald , Hartmann Roger
Published: January 2014

Transport of sediment under wind‐driven rains is generally not accounted for in equations for sediment transport by wind. However, the contribution of this rainsplash–saltation process can be substantial. Wind‐tunnel experiments, in which horizontal fluxes were measured at four heights above a sand surface, were conducted to study sediment transport under wind‐driven rain and rainless wind conditions. It was shown that the horizontal flux could be described by a single exponential equation under both conditions. By integration of the horizontal flux over the height of rainsplash–saltation and saltation, respectively, the sediment transport rate was computed. Hence the obtained data set was used to validate the sediment transport models of Cornelis et al., which were developed from measurements of vertical deposition fluxes under wind‐driven rain and rainless wind conditions. The data followed the models very well, which suggests that they are adequate to predict the transport rate of sediment under wind‐driven rain and rainless wind.
Calibration of Capacitance Probe Sensors using Electric Circuit Theory
Authors: Kelleners T. J. , Soppe R. W. O. , Robinson D. A. , Schaap M. G. , Ayars J. E. , Skaggs T. H.
Published: January 2014

Capacitance probe sensors are an attractive electromagnetic technique for estimating soil water content. There is concern, however, about the influence of soil salinity and soil temperature on the sensors. We present an electric circuit model that relates the sensor frequency to the permittivity of the medium and that is able to correct for dielectric losses due to ionic conductivity and relaxation. The circuit inductance L is optimized using sensor readings in a modified setup where ceramic capacitors replace the sensor's capacitance plates. The three other parameters in the model are optimized using sensor readings in a range of nonconductive media with different permittivities. The geometric factor for the plastic access tube gp is higher than the geometric factor for the medium gm, indicating that most of the electromagnetic field does not go beyond the access tube. The effect of ionic conductivity on the sensor readings is assessed by mixing salts in three of the media. The influence is profound. The sensor frequency decreases with increasing conductivity. The effect is most pronounced for the medium with the lowest permittivity. The circuit model is able to correct for the conductivity effect on the sensors. However, as the dielectric losses increase, the frequency becomes relatively insensitive to permittivity and small inaccuracies in the measured frequency or in the sensor constants result in large errors in the calculated permittivity. Calibration of the capacitance sensors can be simplified by fixing two of the constants and calculating the other two using sensor readings in air and water.
Dependence of Zeta Potential and Soil Hydraulic Conductivity on Adsorbed Cation and Aqueous Phase Properties
Authors: Aydin Mehmet , Yano Tomohisa , Kilic Seref
Published: January 2014

This paper deals with the effects of pH, electrolyte concentration, and exchangeable Na percentage (ESP) on electrophoretic mobility (EM)/zeta potential (ζp) of clay particles and hydraulic conductivity (HC) of the clay/sand mixtures. The soils taken from Japan and Kazakhstan were used for obtaining clay fractions. For EM determinations, clay suspensions were prepared at a concentration of 4 g of clay per 100 mL of distilled water (DW) or electrolyte solution. The electrophoretic mobilities were measured using Burton apparatus with water‐cooling system and converted into ζp. For HC measurements, clay/sand mixtures were designated 16:84. Columns of these mixtures were prepared by packing 120 g of mixtures into 50‐mm diameter plastic cylinders to a bulk density of about 1.4 g cm−3Results showed clearly that the mobility was very sensitive to the ion valence adsorbed on the clay. The negative electrophoretic mobilities of homoionic Na– Ariake soil (AS) clay and Na–Kzyl‐Orda soil (KS) clay were 2.13 × 10−8and 2.14 × 10−8m2s−1V−1, respectively, whereas Ca clays flocculated. The ζp values of AS clay and KS clay, as a function of the ESP, varied between −12.83 and −26.84 mV, and −5.68 and −27.00 mV, respectively, at ESP > 30. Although the smectitic AS clay was less sensitive than the micaceous KS clay to pH changes during electrophoresis experiment, its HC also was affected by pH changes. Decreased pH from 7 to 5 could easily result in two to three times high HC values for both clay/sand mixtures. The EM of both soil clays was similar at pH 10 to 12, and exchangeable Na percentages 90 to 100. Sharp increases in EM and decreases in HC of AS clay were observed at exchangeable Na percentages 50 and 60, respectively. Similar trends related to EM were also obtained for the KS clay. However, salt concentration of the suspension solution did not have consistent effect on the EM values. This behavior of the clays was consistent with HC observation. The results indicated that HC of the clay/sand mixtures could be correlated to ζp. The saturated HC of the mixtures was found to change as an exponential function of the ζp of clay particles.
Soil Carbon and Nitrogen Mineralization
Authors: Haney R. L. , Franzluebbers A. J. , Porter E. B. , Hons F. M. , Zuberer D. A.
Published: January 2014

Carbon and N mineralization in dried soils that are rewetted has been proposed as a rapid index of C and N mineralization potential and to reflect soil management, but further research is needed on effects of soil type and drying temperature for this approach. The objective of this study was to determine the effect of maintaining soil field moisture or drying soil at 40, 60, or 100°C followed by rewetting and a 3‐d incubation on C and N mineralization across diverse soil types. Strong correlations between C mineralized in 24 d from field moist soils vs. C mineralized in 24 h from soils dried at 40 or 60°C were observed. Carbon mineralization values for 24 vs. 3 d resulted in nearly linear relationships for all drying treatments. Nitrogen mineralization in 24 d from moist vs. dried at 40 or 60°C and rewetted soils were also highly correlated with field moist N mineralization. The drying and rewetting pre‐incubation of soil followed by a 3‐d incubation was shown to be a useful indicator of longer‐term (24 d) C mineralization potential. Nitrogen mineralization potential may also be obtained after drying/rewetting at 40 or 60°C without the need for keeping soil in a continuously field‐moist state.
Nitrogen Use Efficiency of 15N‐labeled Poultry Manure
Authors: Thomsen Ingrid K.
Published: January 2014

The timing between poultry manure N mineralization and crop N uptake as influenced by manure application time (winter or spring) and bedding material [barley (Hordeum vulgare L.) straw, wood chips, or no bedding] was investigated with 15N‐labeled poultry manure. Reference plots received either a high or low dose of 15N‐labeled mineral fertilizer in spring or were without manure and fertilizer N. The 15N recovery was measured for 1 yr in spring barley and for the two following years in perennial ryegrass (Lolium perenne L.). Barley grain yield and N uptake were significantly higher when poultry manure had been applied in spring compared with application in winter. The barley 15N recovery was 15% for winter‐applied manure and 38% for manure applied in spring. The recovery of manure 15N from spring‐applied poultry manure corresponded to 82% of what was taken up by barley in the fertilizer‐amended soil, where 15N recovery averaged 46%. Bedding in poultry manure had no effect on crop 15N uptake. Ryegrass recoveries of 15N from manure and fertilizer were 4 to 6% in the second year and 1 to 2% in the third year. After 3 yr, 94% of 15N of spring‐applied poultry manure and 88% of mineral fertilizer were recovered in crops plus soil. Total recovery of 15N from winter‐applied poultry manure averaged 56%. The bedding had no influence on total 15N recovery. It is concluded that although poultry manure contains bedding with high C:N ratios which potentially could immobilize N for a period, optimum time for manure application is in the spring.
A COMPARISON OF SEVERAL APPROACHES TO MONITOR WATER‐TABLE FLUCTUATIONS
Authors: Morgan C. P. , Stolt M. H.
Published: January 2014

Relationships established between redoximorphic features and the seasonal high water table should be based on the most accurate representation of water‐table fluctuations. In this study, we compared hydrographs developed using water‐table readings made at weekly intervals over a 12‐wk period to those developed over the same period for an adjacent water‐table well using measurements recorded every half hour by a data logger. The hydrograph developed using the weekly readings underestimated the height of the water table for 33% of the study period. A simple inexpensive maximum water‐table recording device (MWTRD) was developed to record the highest level the water table reached during the interval between site visits. Two approaches are demonstrated for improving the accuracy of the weekly hydrograph using data collected by the MWTRD along with a limited amount of logger data. These adjusted hydrographs accounted for >80% of the underestimation of the height of the water table compared with the weekly measurements.
Calcium Loss in Central European Forest Soils
Authors: Jandl Robert , Alewell Christine , Prietzel Jörg
Published: January 2014

The Ca concentration in the soil of many Central European forest ecosystems is declining. The evidence for the extent of Ca loss in Norway spruce (Picea abies L. [Karst.]) forests was investigated from changes in exchangeable Ca between 1985 and 2000 at Weilhartsforst/Upper Austria and from soil solution chemistry between 1992 and 1999 at Coulissenhieb/NE Bavaria. The temporal trend of exchangeable Ca in the soil and the Ca concentration in the soil solution were compared with the change in the Ca concentration in spruce needles. The decline of the pool of exchangeable Ca in the soil within 15 yr was not reflected by the Ca concentration of needles in Austria. Analysis of a large regional database revealed that soil exchangeable Ca was only loosely correlated with the Ca level in needles and entirely unrelated to the rate of forest growth. At the Bavarian site a decline in soil solution Ca concentration and Ca/Al and a decline in needle Ca concentrations were observed; however, changes in foliar Ca concentrations were not statistically correlated with soil solution chemistry. This would suggest that trees access Ca from sources that are not evident from soil chemical data. Despite ongoing Ca losses, we did not identify an immediate stress for the forest ecosystems.
Nitrous Oxide Emission and Methane Consumption Following Compaction of Forest Soils
Authors: Teepe Robert , Brumme Rainer , Beese Friedrich , Ludwig Bernard
Published: January 2014

Fluxes of the greenhouse gases, N2O and CH4, were measured across a skid trail at three beech (Fagus sylvaticaL.) forest sites with soils of different texture. At each site three skid trails were established by applying two passes with a forwarder. Soil compaction in the middle of the wheel track caused a considerable increase of N2O emissions with values elevated by up to 40 times the uncompacted ones. Compaction reduced the CH4consumption at all sites by up to 90%, and at the silty clay loam site its effect was such that CH4was even released. These changes in N2O and CH4fluxes were caused by a reduction in macropore volume and an increase of the water‐filled pore space (WFPS). Additionally, the slipping of the forwarder's wheels led to a mixing of the humus layer with the mineral soil, which resulted in a new layer. This layer reduced gas exchange between the soil and the atmosphere. Trace gas fluxes were altered in the trafficked soil and in the adjacent areas. Despite the significant changes in the trace gas fluxes on the skid trails, the cumulative effect of the two gases on the atmosphere was small with respect to total emissions. However, if soil trafficking is not restricted to the established skid trail system the area of compaction and consequently the atmospheric load by greenhouse gases may increase with every harvesting operation.
Total Soil Nitrogen in the Coarse Fraction and at Depth
Authors: Whitney Nicol , Zabowski D.
Published: January 2014

Historically, studies estimating total soil N are based almost exclusively on the ≤2‐mm soil particles (fine soil fraction), and generally have not included that portion of soil >2‐mm (coarse soil fraction) or soil >1‐m depth. This study examined the underestimation of the total soil N pool by following traditional or standard soil sampling and analysis. Seventeen varied soil series plus one soil classified to the level of Great Group were sampled from Alaska, Oregon, Puerto Rico, and Washington. Total soil N in each profile was quantified for the soil fine and coarse fractions, as well as for soil depths >1 m. In soils with a coarse fraction, the average percentage of total soil N contained in the coarse soil fraction ranged from 0.3 to 37%, increasing with an increase in coarse soil mass (the highest percentage of N for an individual profile was 67% in a Cryorthent with 92% coarse fragments). For soils with depths >1 m, the percentage of soil N below 1 m relative to the whole profile ranged from 7 to 35%. An average of 0.03% N concentration in the coarse soil fraction was found for all major genetic mineral horizons. Results of this study indicated that up to one‐half of the total soil N of a profile would have been missed by the combined exclusion of the coarse fraction and soil below 1‐m depth from analysis. The coarse soil fraction may reflect storage and/or potential sources of N not considered in traditional soil N budgets.
Predictive Mechanistic Model of Soil Phosphorus Dynamics with Readily Available Inputs
Authors: Karpinets T. V. , Greenwood D. J. , Ammons J. T.
Published: January 2014

Fertilizer and manure P applications together with cropping practices can have a lasting effect on soil fertility and can result in pollution of waterways. This study was aimed at providing a general model for the long‐term changes in soil P extracted with conventional tests. The model maintains three active pools of soil P: extractable soil P (X), absorbed P that is not extractable but interchanges reversibly with X (Y), and mineral P that provides solubility‐product type buffering of X (Pbuffer). There is also an input for the net P addition. Equations derived from the model define most of the published patterns of response of X found in long‐term field experiments. They underpin a dynamic version of the model that permits annual inputs and calculates the time‐course of the various P pools. A method was devised for calibrating the dynamic version from measurements that are usually made in long‐term experiments. Models calibrated in this way gave good fits to the data from six soils from four countries. Values of the coefficients indicated that solubility product buffering had a decisive influence on the P economy of some but not all soils. The model gave predictions of X that were in good agreement with measurements in three long‐term experiments that were entirely independent of those used for calibrating the model. Other possible methods of calibration are discussed. The model concisely represents key factors affecting the dynamics of X over the long term and has both interpretative and predictive value.
Potassium Buffering Characteristics of Three Soils Low in Exchangeable Potassium
Authors: Wang Jim J. , Harrell Dustin L. , Bell Paul F.
Published: January 2014

Plant availability of soil K is controlled by dynamic interactions among its different pools. Misunderstanding of these dynamics leads to mismanagement of soil fertility. This study was conducted to evaluate buffering characteristics of low exchangeable‐K soils that showed different sugarcane (Saccharum spp.L.) responses to K amendment. Three silt loams, Crowley (fine, smectitic, hyperthermic Typic Albaqualfs), Dundee (fine‐silty, mixed, active, thermic Typic Endoaqualfs), and Norwood (fine‐silty, mixed, superactive, hyperthermic Fluventic Eutrudepts), were evaluated by using a modified quantity/intensity (Q/I) approach, which allows partitioning of K changes in the soil–solution system into exchangeable and nonexchangeable pools. Total potential buffering capacity (PBCt) was found to correlate significantly (r= 0.97,P< 0.01) with the buffering capacity due to nonexchangeable K (PBCn) rather with that due to exchangeable K (PBCe). Impact factor (β), a measure of effect of added K on nonexchangeable K, was inversely correlated with a soil's conversion magnitude (α) of converting added K to exchangeable K (r= 0.95,P< 0.01). Of the three soils, Dundee exhibited much smaller β values than Crowley and Norwood but the soil converted much of added K to exchangeable K (60–65%) throughout its surface and subsurface soils. Both Crowley and Norwood possessed higher PBCtas well as higher PBCnand PBCethan Dundee, but Crowley required relatively lower critical exchangeable K (EKr) and solution K (CKr) levels below which release of nonexchangeable K was initiated. The overall results indicated that the partitioned Q/I approach could be used to explicitly evaluate short‐term K dynamics in soil–solution systems. The nonexchangeable K buffering characteristics along with the differences between critical levels (EKror CKrand EK0or CK0) have important implications in assessing the likelihood of nonexchangeable K release and could be calibrated for soil fertility management.
Mobility and Lability of Phosphorus from Granular and Fluid Monoammonium Phosphate Differs in a Calcareous Soil
Authors: Lombi E. , McLaughlin M. J. , Johnston C. , Armstrong R. D. , Holloway R. E.
Published: January 2014

Phosphorus availability is a major factor limiting crop production in highly calcareous soils. Recent field trials on calcareous soils in southern Australia have shown that fluid fertilizers may provide a useful alternative to granular fertilizer products. Fluid sources of P enhance P uptake and yield when compared with granular fertilizers applied at the same rate. This work aimed to compare the behavior of one fluid (technical grade monoammonium phosphate, TG‐MAP) and one granular (monoammonium phosphate, MAP) form of P fertilizer in a highly calcareous soil. Changes in soil pH, P diffusion, solubility, and lability (using isotopic dilution techniques) were determined at different distances from the point of application over 5 wk. Furthermore, reaction products in MAP granules were investigated using spectroscopic techniques. The results indicated that P from fluid TG‐MAP diffused more and was more available than P supplied as granular MAP. Also, X‐ray diffraction (XRD) and energy dispersive X‐ray microanalyses (EDXMA) of the MAP granules indicated that a significant percentage (12%) of the initial P remained in the granules even after 5 wk of incubation in the soil. The enhanced P availability of fluid fertilizers observed in field trials compared with granular forms is discussed in relation to differences in the dissolution, diffusion, and reaction processes in soils.
Carbon Pools and Accumulation Rates in an Age‐Series of Soils in Drained Thaw‐Lake Basins, Arctic Alaska
Authors: Bockheim J. G. , Hinkel K. M. , Eisner W. R. , Dai X. Y.
Published: January 2014

We examined soils in 20 drained thaw‐lake basins (DTLBs) near Barrow representing four age classes: young [0–50 years before present (BP)], medium (50–300 BP), old (300–2000 BP), and ancient (2000–5500 BP). In addition, we examined an erosional remnant that is about 8000 yr in age with deep organic deposits. There are significant age‐related differences in thickness of the organic layer, which for DTLBs represents surface organic accumulation since lake drainage. The lower portion of the organic layer progresses in decomposition stage from fibric in young basins to sapric in ancient basins and the erosional remnant. Whereas extractable organic matter (humic‐ and fulvic‐acid fractions) in the organic layer decreases, the nonextractable portion (humin) increases with basin age. There are significant age‐related differences (p = 0.027) in soil organic carbon (SOC) of the organic layer; however, there were no significant differences in C pools for other depths or within the upper 100 cm. Profile SOC pools in DTLBs average 48 kg m−3, which is less than elsewhere on the Arctic Coastal Plain (62 kg m−3). From a depth of 100 to approximately 160 cm, SOC pools average 3.2 kg C m−2 dm−1, confirming that there are large amounts of SOC below the traditional reporting depth of 100 cm. The spatial variability of SOC pools increases with relative basin age class and is likely because of increased variability in hydrology related to enrichment of ground ice in the upper permafrost. The long‐term net accumulation (during the last 5500 yr) of SOC is 13 g m−2 yr−1
Passive Pan Sampler for Vadose Zone Leachate Collection
Authors: Barzegar A. Rahman , Herbert Stephen J. , Hashemi A. Masoud , Hu C. S.
Published: January 2014

Sampling agrochemicals in the vadose zone provides an early warning system for ground water pollution. However, accurate in situ determination of agrochemicals in the vadose zone is often not feasible because of lack of appropriate instrumentation. This paper presents a new passive soil water sampler to effectively collect vadose zone leachate. The passive pan sampler (PPS), and a suction cup lysimeter (SCL) were positioned in soil columns. Two soil types were used. Vacuums applied to both PPS and SCL were adjusted to tensiometer readings in each soil column. Measurements included volumetric soil water content by time domain reflectometry (TDR), soil water potentials by tensiometers at three positions in each soil column, and the cumulative leachate collection (CLC) for the PPS, SCL, and free drainage (FD). Measurements were made at two initial soil water potentials of less than −10 kPa and −20 to −25 kPa, referred to high (HSWP) and low (LSWP) soil water potentials. Results indicated that the PPS performed well in both soil types irrespective of the initial soil water potential. Leachate collected by SCLs in the soils was lower than that collected by PPSs. The maximum CLC for silt loam soil ranged from 9.6 to 10.0 mL cm−2at both water potentials for PPS, 1.6 to 2.1 mL cm−2at both water potentials for SCL, and 0 to 2.0 mL cm−2at HSWP for FD and 0 to 0.7 mL cm−2at LSWP for FD, respectively. The corresponding values for the sandy loam soil were 8.0, 2.7, and 5.2 mL cm−2, for PPS, SCL, and FD, respectively. The leachate collection efficiencies of PPS at HSWP (98%) and LSWP (99%) were significantly (P< 0.01) higher than for SCL at HSWP (59%) and LSWP (31%), indicating greater performance of the PPS.
Soil Carbon‐13 Natural Abundance under Native and Managed Vegetation in Brazil
Authors: Wilcke Wolfgang , Lilienfein Juliane
Published: January 2014

The conversion of native Cerrado vegetation (a mixed C3 and C4 vegetation) to Pinus caribaea Morelet plantations (a pure C3 vegetation) and to Brachiaria decumbens stapf pastures (a pure C4 vegetation) likely affects the C cycle. We used the natural abundance of 13C (δ13C) in vegetation and soil to: (i) quantify the contributions of C3 and C4 plants to the organic matter input into the soil under Cerrado vegetation and (ii) determine the degree of the replacement of original Cerrado‐derived C by Pinus plantations and pastures. The mean δ13C value of the soils (Anionic Acrustoxes) under Cerrado vegetation ranged from −20.5 to −19.7‰, which was dissimilar to the mass‐weighted mean δ13C signal of the aboveground biomass (−25.8‰). This was because grasses being C4 plants contributed 11% to the aboveground biomass but about 50% of the organic matter input to the soil, which was estimated with a simple mixing model of the C3 and C4 13C signals. After 12 and 20 yr, only 30% of the original organic matter in the topsoil was replaced by new organic matter under pasture or Pinus plantation, respectively. This turnover took place without significantly changing the C storage of the top 2 m of the soil (17–19 kg m−2). The C replacement under Pinus affected only the top 0.15 m. Our results demonstrate that the C replacement in soils following land‐use change in the Oxisols of this study takes several decades and is considerably slower under Pinus than under pasture.
Contributions of Edward Elway Free to American Soil Science in the Early 1900s
Authors: Brevik Eric C.
Published: January 2014

The early 1900s were a time of rapid growth in American soil science. Edward Elway Free is not well known but produced some excellent work during this time. Free majored in chemistry at Cornell University and graduated in 1906. He worked as a chemist with the University of Arizona from 1906–1907, as a physical scientist with the Bureau of Soils from 1907–1912, and as a private consultant in chemistry and physics after 1912. In 1917 Free earned a Ph.D. from Johns Hopkins University. He continued to run his consulting company until his death on 24 Nov. 1939. Publication trends over Free's career include publications in chemistry (1908–1910), eolian processes and soil physics (1909–1912), and economic resources (1912–1917). After 1917 his agriculturally related publications were in soil aeration and weather and climate.
Short‐Term Effects of Land Leveling on Soil Chemical Properties and Their Relationships with Microbial Biomass
Authors: Brye K. R. , Slaton N. A. , Mozaffari M. , Savin M. C. , Norman R. J. , Miller D. M.
Published: January 2014

Spatial variability and distributions of soil chemical properties and the relationships between soil chemical and biological properties are not well characterized in agroecosystems that have been land leveled to facilitate more uniform delivery of irrigation water. The objectives of this study were to characterize the short‐term impacts of land leveling on the magnitudes, spatial variability, and spatial distributions of soil chemical properties and to evaluate the impact of land leveling on the relationships between soil chemical properties and microbial biomass in a Stuttgart silt loam (fine, smectitic, thermic Albaqultic Hapludalf) used for irrigated soybean [Glycine max (L.) Merr.] and rice (Oryza sativa L.) production in the Mississippi Delta region of eastern Arkansas. A grid‐sampling approach was used to characterize pre‐ and postleveling soil chemical properties and microbial biomass. Results of this study demonstrate that land leveling, a severe form of anthropogenic soil disturbance, causes significant alteration of the magnitudes, spatial variability, and spatial distributions of many soil chemical properties. Soil electrical conductivity (EC) and the contents of P, K, Mg, Na, S, Mn, and Cu in the top 10 cm significantly increased, while soil pH and organic matter (OM) and Fe contents significantly decreased, as a result of land leveling. Land leveling also significantly altered many linear relationships among soil chemical properties and microbial biomass. The benefit of improved water distribution must be weighed against the relatively severe and immediate alteration of soil properties and natural processes brought on by land leveling. Further research is required to ascertain long‐term effects of altered soil biogeochemical properties on crop growth as a result of land leveling.
Separation of solids and disinfection for agronomical use of the effluent from a UASB reactor
Authors: Sundefeld Junior G. C. , Piveli R. P. , Cutolo S. A. , Ferreira Filho S. S. , Santos J. G.
Published: January 2014

The present work addresses the preparation of the effluent from a full-scale upflow anaerobic sludge blanket (UASB) reactor for drip irrigation of orange crops. The pilot plant included a lamella plate clarifier followed by a geo-textile blanket filter and a UV disinfection reactor. The clarifier operated with a surface load of 115 m3m−2d−1, whereas the filter operated with 10 m3m−2d−1. The UV reactor was an open-channel type and the effective dose was approximately 2.8 W h m−3. The effluent of the UASB reactor received 0.5 mg L−1 cationic polyelectrolyte before entering the high-rate clarifier. Suspended solids’ concentrations and Escherichia coli and helminth egg's densities were monitored throughout the treatment system for 12 months. Results showed that the total suspended solids concentration in the filter effluent was lower than 7 mg L−1 and helminth density was below 1.0 egg L−1. The UV disinfection demonstrated the ability to produce a final effluent with E. coli density lower than 103MPN/100 mL (MPN: most probable number) during the entire process. Thus, the World Health Organization standards for unrestricted crop use were met. Agronomic interest parameters were controlled and it was possible to identify the important contribution of treated sewage in terms of the main nutrients.
Characterizing o- and p-nitrophenols adsorption onto innovative activated carbon prepared from date pits
Authors: Altaher Hossam , Dietrich Andrea M.
Published: January 2014

The production and performance of activated carbon prepared from date pits was investigated. Date pits are an abundant local waste product in many countries; converting them to a commercial product would increase the sustainability of this fruit crop. The date pit activated carbon was shown to have similar characteristics of pore size and surface functional groups as other commercial carbons. Batch experiments were conducted with o- and p-nitrophenol to evaluate the performance of this carbon. Results were analyzed according to Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherms. The adsorption capacity of o-nitrophenol was 142.9 mg/g while that of p-nitrophenol was 108.7 mg/g. The adsorption process was physical in nature. The position of the −NO2 group in the benzene ring has a considerable effect on the adsorption capacity and rate of uptake. The kinetic results showed that a pseudo second-order model appropriately describes the experimental data. The analysis of kinetic data revealed that the mechanism of adsorption is complex with both liquid film diffusion and intraparticle diffusion contributing to adsorption of both adsorbates.
Dielectric barrier discharge induced degradation of diclofenac in aqueous solution
Authors: Rong Shaopeng , Sun Yabing , Zhao Zehua , Wang Huiying
Published: January 2014

A dielectric barrier discharge (DBD) reactor as one of the advanced oxidation processes was applied to the degradation of diclofenac in aqueous solution. The various parameters that affect the degradation of diclofenac and the proposed evolutionary process were investigated. The results indicated that the inner concentrations of 10 mg/L diclofenac can be all removed within 10 min under conditions of 50 W and pH value of 6.15. The existence of Fe2+ in the liquid phase can promote the degradation of diclofenac. But it was rather ineffective in mineralization, because the intermediates containing the aromatic rings were recalcitrant to be degraded. Five intermediates were identiﬁed by liquid chromatography-mass spectrometry (LC-MS), the OH · radical and O3 were the major reactive species, and played an important role in the degradation of diclofenac. The toxicity of diclofenac degraded by DBD was assessed and the results indicated the efficiency of the DBD in the detoxification of the diclofenac solution.
Modelling ammonium-oxidizing population shifts in a biofilm reactor
Authors: Vannecke T. P. W. , Bernet N. , Steyer J.-P. , Volcke E. I. P.
Published: January 2014

The dynamic reactor behaviour of a nitrifying inverse turbulent bed reactor, operated at varying loading rate, was described with a one-dimensional two-step nitrification biofilm model. In contrast with conventional biofilm models, this model includes the competition between two genetically different populations of ammonia-oxidizing bacteria (AOB), besides nitrite-oxidizing bacteria (NOB). Previously gathered experimental evidence showed that different loading rates in the reactor resulted in a change in the composition of the AOB community, besides a different nitrifying performance. The dissolved oxygen concentration in the bulk liquid was put forward as the key variable governing the experimentally observed shift from Nitrosomonas europaea (AOB1) to Nitrosomonas sp. (AOB2), which was confirmed by the developed one-dimensional biofilm model. Both steady state and dynamic analysis showed that the influence of microbial growth and endogenous respiration parameters as well as external mass transfer limitation have a clear effect on the competition dynamics. Overall, it was shown that the biomass distribution profiles of the coexisting AOB reflected the ecological niches created by substrate gradients.
Becoming an Academic for the Twenty-First Century: What Will Count as Teaching Quality in Higher Education
Authors: Jasman Anne , Blass Eddie , Shelley Steve
Published: January 2014

This article explores quality in university teaching using a ‘futures’ perspective. In a recent article by Blass and colleagues, a number of scenarios were developed to explore the type of higher education workforce that might be needed within the UK by 2035. In discussion of these scenarios — leading knowledge creation, responsive knowledge creation, regional conglomerates, no government funding and total government funding — the team were mindful of how these scenarios would impact on academic work and the workforce needed to undertake different and perhaps a more differentiated set of work roles, responsibilities and ways of working. However, the issue of what counts as quality within these possible scenarios was not considered. In this article the definitions and differentiation of teacher and teaching quality are explored. Recent trends in Australian and English higher education policy in relation to teaching quality are also discussed. Teaching quality is then considered in relation to the underlying values and assumptions that might operate within each of these scenarios about teaching. The authors then speculate on the impact this would have on what might count as quality in teaching in 2020, and what academics may have to face within each of these scenarios in relation to their work roles, ways of working and opportunities for career progression. In conclusion, the authors suggest that the concept of ‘teaching’ in higher education may need to be radically reconsidered to match the needs of students whatever scenario may develop in higher education.
Researching amid the Heat and Noise of Political Debate
Authors: Thrupp Martin
Published: January 2014

This article discusses the everyday politics surrounding research on a controversial government policy. The research in question is the Research, Analysis and Insight into National Standards (RAINS) project on National Standards in New Zealand primary schools being undertaken by the author. This three-year study was funded by the New Zealand primary teachers' union, the NZEI, an organisation opposed to the National Standards policy. The project was quickly attacked by a cabinet minister and the media but there have also been significant accomplishments in carrying out and reporting the research and in relevant activism. As the article discusses the political setbacks and successes while undertaking the research, it reflects on issues such as research funding, research ‘independence’, the reporting of findings from controversial research projects, the tensions between being a researcher and an activist and the importance of supportive networks. The article provides a case study of how challenges to the legitimacy of research and academic involvement in public debate may need to be anticipated and addressed by researchers much like other aspects of their work.
Responsive or Responsible? Democratic Education for the Global Networked Society
Authors: Biesta Gert
Published: January 2014

In this article, which is based on an invited keynote presentation given at the 14th biennial conference of the European Association for Research on Learning and Instruction (EARLI), the author discusses the question of how education should respond to the ongoing rise of the global networked society. He provides an analysis of the history and transformation of global networks, making a distinction between centred, decentred and pseudo-decentred networks. Against this background he discusses two different educational responses to the global networked society. He characterises the first as a responsive response, one where education is urged to adapt itself to the demands of the global networked society. He discusses the twenty-first-century skills movement as an example of such a response. He characterises the second as a responsible response, one that takes a more critical position vis-à-vis the different manifestations and demands of such a society. He argues that the proper educational response has to be a responsible rather than a responsive one, on the assumption that education should always be understood as more than just a fonction of existing social and societal orders because it comes with a duty to resist. He shows how this duty is both inherently educational and inherently democratic.
SGLT-2 Inhibitors: A New Mechanism for Glycemic Control
Authors: Chao Edward C.
Published: January 2014

IN BRIEF

Glucosuria, the presence of glucose in the urine, has long been regarded as a consequence of uncontrolled diabetes. However, glucose excretion can be induced by blocking the activity of the renal sodium-glucose cotransporter 2 (SGLT-2). This mechanism corrects hyperglycemia independently of insulin. This article provides an overview of the paradigm shift that triggered the development of the SGLT-2 inhibitor class of agents and summarizes the available evidence from clinical studies to date.
Multicenter prospective evaluation of dogs with trauma
Authors: Hall Kelly E. , Holowaychuk Marie K. , Sharp Claire R. , Reineke Erica
Published: January 2014

Objective—To determine hospital admission variables for dogs with trauma including values determined with scoring systems (animal trauma triage [ATT], modified Glasgow coma scale [MGCS], and acute patient physiologic and laboratory evaluation [APPLE] scores) and the usefulness of such variables for the prediction of outcome (death vs survival to hospital discharge).

Design—Prospective, multicenter, cohort study.

Animals—315 client-owned dogs.

Procedures—By use of a Web-based data capture system, trained personnel prospectively recorded admission ATT, MGCS, and APPLE scores; clinical and laboratory data; and outcome (death vs survival to discharge) for dogs with trauma at 4 veterinary teaching hospitals during an 8-week period.

Results—Cause of injury was most commonly blunt trauma (173/315 [54.9%]) followed by penetrating trauma (107/315 [34.0%]), or was unknown (35/315 [11.1%]). Of the 315 dogs, 285 (90.5%) survived to hospital discharge. When 16 dogs euthanized because of cost were excluded, dogs with blunt trauma were more likely to survive, compared with dogs with penetrating trauma (OR, 8.5). The ATT (OR, 2.0) and MGCS (OR, 0.47) scores and blood lactate concentration (OR, 1.5) at the time of hospital admission were predictive of outcome. Surgical procedures were performed for 157 (49.8%) dogs; surgery was associated with survival to discharge (OR, 7.1).

Conclusions and Clinical Relevance—Results indicated ATT and MGCS scores were useful for prediction of outcome for dogs evaluated because of trauma. Penetrating trauma, low blood lactate concentration, and performance of surgical procedures were predictive of survival to hospital discharge. The methods enabled collection of data for a large number of dogs in a short time.
Evaluation of the radiographic infrapatellar fat pad sign of the contralateral stifle joint as a risk factor for subsequent contralateral cranial cruciate ligament rupture in dogs with unilateral rupture: 96 cases (2006–2007)
Authors: Fuller Mark C. , Hayashi Kei , Bruecker Kenneth A. , Holsworth Ian G. , Sutton Jessie S. , Kass Philip H. , Kantrowitz Brett J. , Kapatkin Amy S.
Published: January 2014

Objective—To determine prevalence of the contralateral radiographic infrapatellar fat pad sign and contralateral radiographic degenerative sign (degenerative changes) and evaluate both signs as risk factors for subsequent contralateral cranial cruciate ligament (CrCL) rupture in dogs with unilateral CrCL rupture.

Design—Retrospective cohort study.

Animals—96 dogs with unilateral CrCL rupture and 22 dogs with bilateral CrCL rupture.

Procedures—Dogs with unilateral CrCL rupture were classified as having normal (n = 84) or abnormal (12) contralateral stifle joints on the basis of joint palpation. Associations between potential predictive variables and rates of subsequent contralateral CrCL rupture were evaluated.

Results—Of the 84 dogs with unilateral CrCL rupture in which the contralateral stifle joint was palpably normal, 29 (34.5%) had a contralateral fat pad sign and 31 (36.9%) had a degenerative sign. All dogs with unilateral CrCL rupture in which the contralateral stifle joint was palpably abnormal had a contralateral fat pad sign and degenerative sign. The contralateral fat pad sign was the most important risk factor for subsequent rupture of the contralateral CrCL. For dogs with unilateral CrCL rupture and palpably normal contralateral stifle joint with and without a contralateral fat pad sign, median time to subsequent rupture was 421 and 1,688 days, respectively, and the 3-year probability of subsequent rupture was 85.3% and 24.9%, respectively.

Conclusions and Clinical Relevance—Bilateral stifle joint radiography should be performed for all dogs with CrCL rupture. Bilateral stifle joint arthroscopy should be considered for dogs with a contralateral fat pad sign.
Relationships among video gaming proficiency and spatial orientation, laparoscopic, and traditional surgical skills of third-year veterinary students
Authors: Millard Heather A. Towle , Millard Ralph P. , Constable Peter D. , Freeman Lyn J.
Published: January 2014

Objective—To determine the relationships among traditional and laparoscopic surgical skills, spatial analysis skills, and video gaming proficiency of third-year veterinary students.

Design—Prospective, randomized, controlled study.

Sample—A convenience sample of 29 third-year veterinary students.

Procedures—The students had completed basic surgical skills training with inanimate objects but had no experience with soft tissue, orthopedic, or laparoscopic surgery; the spatial analysis test; or the video games that were used in the study. Scores for traditional surgical, laparoscopic, spatial analysis, and video gaming skills were determined, and associations among these were analyzed by means of Spearman's rank order correlation coefficient (rs).

Results—A significant positive association (rs = 0.40) was detected between summary scores for video game performance and laparoscopic skills, but not between video game performance and traditional surgical skills scores. Spatial analysis scores were positively (rs = 0.30) associated with video game performance scores; however, that result was not significant. Spatial analysis scores were not significantly associated with laparoscopic surgical skills scores. Traditional surgical skills scores were not significantly associated with laparoscopic skills or spatial analysis scores.

Conclusions and Clinical Relevance—Results of this study indicated video game performance of third-year veterinary students was predictive of laparoscopic but not traditional surgical skills, suggesting that laparoscopic performance may be improved with video gaming experience. Additional studies would be required to identify methods for improvement of traditional surgical skills.
The Tale of Assisted Human Reproduction Canada: A Tragedy in Five Acts
Authors: Baylis Françoise , Downie Jocelyn
Published: January 2014

In the spring of 2012, Assisted Human Reproduction Canada (AHRC)—the federal agency tasked with the oversight of assisted human reproduction in Canada—was abolished through the passage of the omnibus budget bill. This ignominious end was in part a response to the Supreme Court of Canada’s Reference re Assisted Human Reproduction Act. However, as we recount in this article, it was also a result of a series of squandered opportunities to regulate assisted human reproduction in the interests of those who use or are born of assisted human reproductive technologies. This article details the genesis, life, and death of the AHRC. We conclude that many millions of public dollars and many hours of experts’ time have been spent, all for naught.
Of Surrogate Mother Born: Parentage Determinations in Canada and Elsewhere
Authors: Busby Karen
Published: January 2014

This article examines statutory regimes and judicial decisions in Canada on parentage and citizenship for children born to surrogate mothers and compares these laws with those of other countries, especially Britain and Australia. Provincial parentage laws (with the notable exception of Québec) and federal law and policy on citizenship favour an expedited process requiring minimal, if any, judicial or administrative oversight on issues related to exploitation such as free and informed consent or financial arrangements. In contrast, British and Australian processes are more inquisitive, expensive, inflexible, and time consuming. Complicated post-birth parentage and citizenship laws do little to protect women against exploitation because, after the birth, surrogate mothers are almost never reluctant to hand over children to intended parents. As long as a genetic link is established between an intended parent and the child, concerns about child trafficking should also be assuaged. Once a child is born, and absent the rare case where disputes arise between the surrogate mother and the intended parents or where there is no genetic link between the child and an intended parent, it will almost always be in that child’s best interests to establish the child’s parentage and citizenship quickly and with certainty.