bluuebunny/crossref_metadata_2025_split huggingface dataset:
Subsoil Characteristics and Landscape Position Affect Productivity of Reconstructed Mine Soils
Authors: Merrill Stephen D. , Ries Ronald E. , Power James F. 
Published: July 2010

AbstractThe placement of soil materials on minespoils during reclamation affects soil profile and landscape aspects of soil productivity. We hypothesized that the productivity of soil reconstructed by topsoil‐subsoil placement on sodic minespoil would be influenced by subsoil characteristics. A 1.4‐ha double wedge was constructed in west‐central North Dakota (annual precipitation 440 mm) from three subsoil materials (1.2‐m thickness at peak) placed in strips over smoothed minespoils so that north‐ and south‐facing slopes were 5 and 1.5%, respectively. Material mostly from B horizons of dominantly Argiboroll soils was used for subsoil treatments: (A) 50% clay; (B) 29% clay; and (C) 13% clay. Subsoils were covered with 0.2 m of mostly A horizon topsoil. Forage yields of crested wheatgrass [CWG, Agropyron desertorum (Fisch.) Schult.] were highest on C subsoil plots 4 yr out of 5 observed, and Russian wildrye [RWR, Psathyrostchys juncea (Fisch.) Nevshi] were highest on C subsoil plots 3 yr out of 4 observed. In contrast, 2 yr of spring wheat (Triticum aestivum L.) seed yields (824 kg ha−1 avg.) were 20 to 50% larger on A subsoil plots than on C subsoil, with B yields intermediate. Forage grass yields on north sideslopes of C subsoil plots averaged 1370 and 1040 kg ha−1 for CWG and RWR, about 20 to 60% greater than yields on other positions and subsoils. The largest spring wheat yields, 1068 kg ha−1, occurred on north sideslope positions of A subsoil plots. Sandy loam subsoils can enhance forage grass yields in rolling lands, while spring wheat yields can be increased by subsoils with greater water‐holding capacity.
High‐Resolution Bulk Density Images, Using Calibrated X‐ray Radiography of Impregnated Soil Slices
Authors: Bresson L. M. , Moran C. J. 
Published: July 2010

AbstractBulk density of undisturbed soil samples can be measured using computed tomography (CT) techniques with a spatial resolution of about 1 mm. However, this technique may not be readily accessible. On the other hand, x‐ray radiographs have only been considered as qualitative images to describe morphological features. A calibration procedure was set up to generate two‐dimensional, high‐resolution bulk density images from x‐ray radiographs made with a conventional x‐ray diffraction apparatus. Test bricks were made to assess the accuracy of the method. Slices of impregnated soil samples were made using hardsetting seedbeds that had been gamma scanned at 5‐mm depth increments in a previous study. The calibration procedure involved three stages: (i) calibration of the image grey levels in terms of glass thickness using a staircase made from glass cover slips, (ii) measurement of ratio between the soil and resin mass attenuation coefficients and the glass mass attenuation coefficient, using compacted bricks of known thickness and bulk density, and (iii) image correction accounting for the heterogeneity of the irradiation field. The procedure was simple, rapid, and the equipment was easily accessible. The accuracy of the bulk density determination was good (mean relative error 0.015). The bulk density images showed a good spatial resolution, so that many structural details could be observed. The depth functions were consistent with both the global shrinkage and the gamma probe data previously obtained. The suggested method would be easily applied to the new fuzzy set approach of soil structure, which requires generation of bulk density images. Also, it would be an invaluable tool for studies requiring high‐resolution bulk density measurement, such as studies on soil surface crusts.
Cadmium and Cobalt Desorption Kinetics from Soil Clays: Effect of Sorption Period
Authors: McLaren Ronald G. , Backes Clare A. , Rate Andrew W. , Swift Roger S. 
Published: July 2010

AbstractSoil solution metal concentrations and hence metal bioavailability are controlled by sorption‐desorption reactions at the surfaces of soil colloids. Compared with the numerous studies on sorption of metals by soils, there are relatively few that examine desorption, and even fewer that have measured desorption kinetics. The objective of this study was, using techniques and models developed previously for studies with synthetic oxides, to examine the effect of sorption period on the subsequent desorption kinetics of Cd and Co from two natural soil clay fractions. Cobalt was less readily desorbed from the clay fractions than Cd, but with both metals and clay fractions, increases in sorption period were accompanied by substantial decreases in the proportions of sorbed metal desorbed. As with the oxides studied previously, desorption kinetics for Cd and Co sorbed onto clay fractions were found to be described well by both a two‐site first‐order model and a model involving a lognormal distribution of first‐order rate constants. Reaction half‐lives derived from the models suggested a movement of Cd and Co to slower desorption reactions with increasing sorption period. However, some caution should be used in interpreting such parameters.
Simulation of a Potential Error in Determining Soil Salinity from Measured Apparent Electrical Conductivity
Authors: Friedman Shmulik P. 
Published: July 2010

AbstractA common method for estimating soil salinity is by in situ measurements of the apparent electrical conductivity, ECa, usually by a four‐electrode probe. It is assumed that the ECa can be regarded as taking place in parallel mode by two conductors on a bulk scale: the dissolved (ECb) and the adsorbed (ECs) ions. Therefore, the contribution to the ECa by the soil solution electrolytes, ECb, which serves to assess its salinity, can be deduced by subtracting the estimated ECs from the measured ECa. This assumption is wrong and leads to an evaluation of ECb higher than its real value. This study was conducted to characterize the error in estimating soil solution electrical conductivity, ECw. A simplified model of a randomly diluted and pore‐size‐distribution‐decorated simple cubic lattice serves to describe the pore network of a saturated soil. It is assumed that only within each pore can the electrical conductance be represented by a sum of two conductors: the dissolved and the adsorbed ions, acting in parallel. Using Monte Carlo lattice simulations, it was shown that the error due to the assumption of parallel mode on a bulk scale increases with increasing broadness of the pore‐size distribution, decreasing connectivities, and increasing cation‐exchange capacity. An illustrative example of real soils, typical of irrigated soils, indicated errors of up to 25% for electrolyte concentrations.
Kinetics of Ammonium Adsorption and Desorption by the Natural Zeolite Clinoptilolite
Authors: Kithome M. , Paul J. W. , Lavkulich L. M. , Bomke A. A. 
Published: July 2010

AbstractThe kinetics of NH+4 adsorption and desorption were investigated on the natural zeolite clinoptilolite to ascertain its ability to adsorb and release the important plant nutrient N in its NH+4 form at various pH values and initial NH+4 concentrations. Kinetics of NH+4 adsorption were evaluated on the samples using solutions containing 140.1, 280.2, 560.4, and 840.6 mg L−1 of NH+4‐N at pH 4, 5, 6, and 7, equilibrated for 5, 10, 15, 20, 30, 45, 60, 75, 90, and 120 min. Samples for NH+4 desorption were equilibrated with 70.1, 280.2, 560.4, and 1401 mg L−1 NH+4‐N solution at pH 4, 5, 6, and 7 for 2.5 h, and adsorbed NH+4 extracted with 2 M KCl for 5, 10, 20, 30, 45, 60, 90, 120, 150, 180, and 300 min. Equilibrium time for NH+4 adsorption ranged from 60 min for 140.1 mg L−1 initial NH+4‐N concentration at pH 4 to 120 min for 840.6 mg L−1 initial NH+4‐N concentration at pH 7. Desorption was nearly complete in 150 min for low initial NH+4 concentrations and 200 min for high initial NH+4 concentrations. Amounts of NH+4 sorbed increased with increasing pH and initial NH+4 concentrations. Models evaluated included the first‐order kinetics, modified Freundlich, parabolic diffusion, Elovich, and heterogeneous diffusion. All the models adequately described the NH+4 adsorption process, with r2 values ranging from 0.955 to 0.999. With the exception of first‐order kinetics, they also described the desorption process well, with r2 values ranging from 0.897 to 0.999, for all pH and initial NH+4 concentrations. Reaction rate coefficients (k) were calculated from the modified Freundlich model and ranged from 0.134 to 0.193 min−1 for the adsorption process, and 0.129 to 0.226 min−1 for the desorption process. The models indicated that NH+4 adsorption and desorption by the zeolite was diffusion controlled. Data from this study indicated the potential use of the tested natural zeolite as an NH+4 adsorbent and a controlled‐release NH+4 fertilizer.
Soil Nitrogen, Microbial Biomass, and Respiration along an Arctic Toposequence
Authors: Cheng Weixin , Virginia R. A. , Oberbauer S. F. , Gillespie C. T. , Reynolds J. F. , Tenhunen J. D. 
Published: July 2010

AbstractTo investigate the interactions among mineral N, C availability, microbial biomass, and respiration in arctic soils, we sampled soils five times during a growing season from a toposequence on a slope in northern Alaska. The toposequence consisted of six vegetative types from the ridge top to the stream bank: lichen heath, dry cassiope, moist carex (Carex spp.), water track, tussock tundra (intertussock), and riparian. The spatial distribution and temporal variation of soil mineral N, microbial biomass, soil C availability, and C turnover were soil type dependent. During the growing season, the concentration of soil NH+4‐N decreased in tussock tundra soils but increased in lichen heath soils. Soil C availability at all locations was the highest at the beginning of the growing season and declined thereafter. The C availability index (CAI) and the potential C turnover rate increased as soils became wetter. Tussock‐forming tundra soil was generally colder than other sites and had high C/N ratios, low amounts of mineral N, and a low potential C turnover index, and therefore, was the least biologically active type. In contrast, water track was the most biologically active site in the sequence and had the highest C and N availability, the highest potential C turnover index, and the highest microbial biomass C and N. The mosaic of diverse plant communities and soil types that comprise arctic landscapes necessitates that accurate estimates of large‐scale C or N budget can only be made by integration of all types of plant communities and soils.
Microvariability in Soil Test, Plant Nutrient, and Yield Parameters in Bermudagrass
Authors: Raun W. R. , Johnson G. V. , Lees H. L. , Sembiring H. , Phillips S. B. , Solie J. B. , Stone M. L. , Whitney R. W. 
Published: July 2010

AbstractThe scale or resolution where distinct differences in soil test and yield parameters can be detected has not been thoroughly evaluated in crop production systems. This study was conducted to determine if large differences in soil test and forage yield parameters were present within small areas (<1 m2). A 2.13 by 21.33 m area was selected for intensive forage and soil sampling from two bermudagrass [Cynodon dactylon (L.) Pers.] pasture sites (Burneyville and Efaw, OK). Each 2.13 by 21.33 m area was partitioned into 490, 0.30 by 0.30 m (1 by 1 ft) subplots. Bermudagrass forage was hand harvested at ground level from each 0.30 by 0.30 m subplot. Prior to forage harvest, spectral radiance readings (red, 671 ± 6 nm; green, 550 ± 6 nm; and near infrared, 780 ± 6 nm) were recorded from each subplot. Composite samples composed of eight soil cores, 0 to 15 cm deep and 1.9 cm in diameter, were collected from each subplot. At both locations, bermudagrass forage yield harvested from 0.30 by 0.30 m subplots ranged from <1300 to >10 000 kg ha−1. Soil pH ranged from 4.37 to 6.29 within the 2.12 by 21.33 m area at Burneyville and 5.37 to 6.34 at Efaw. No P or K fertilizer would have been recommended at Efaw using mean soil test P and K. The range in recommended fertilizer rates would have been 0 to 31 and 0 to 17 kg P ha−1 and 0 to 107 and 0 to 108 kg K ha−1 at Burneyville and Efaw, respectively, if recommendations were based on individual 0.30 by 0.30 m grid data. Significant differences in surface soil test analyses were found when samples were <1 m apart for both mobile and immobile nutrients.
Modeling Rain Erosivity Using Disdrometric Techniques
Authors: Cerro Carlos , Bech Joan , Codina Bernat , Lorente Jeroni 
Published: July 2010

AbstractThe erosive effect produced by direct raindrop impact on the soil surface may be quantified in terms of the raindrop kinetic energy (KE). This variable is usually calculated from the rainfall rate even though a precise description of the raindrop size distribution is required. In this study, raindrop size and fall velocities were measured for 2 yr in Barcelona, Spain, with an optical disdrometer. Fitted drop‐size distributions were used to obtain relationships between raindrop KE and rainfall rate. A comparison between KE calculated from experimental distributions indicated that the lognormal distribution model was most suitable to provide a KE‐rainfall rate relation. Predicted KE values from this relationship had better agreement with observations (differences of 7%) than predicted values from other models based on different rainfall conditions.
Persistence of Soil Structural Modifications Along a Historic Wagon Trail
Authors: Sharratt B. , Voorhees W. , McIntosh G. , Lemme G. 
Published: July 2010

AbstractWagon wheel ruts are still visible along pioneer trails in the USA, which suggests that vehicular traffic can modify soil properties for a century. We compared physical properties of a Barnes loam (fine‐loamy, mixed Udic Haploboroll) across three transects of the 1864 to 1871 Wadsworth Trail. Compaction was evident within wheel ruts of the trail, as penetration resistance and bulk density were 10% greater and water infiltration and air permeability were 50% lower within the wheel ruts than outside the trail. Erosion was also apparent within the wheel ruts, as the greater density could not fully account for the thinner A horizon (60 mm). Our investigation suggests that degradation of soil properties caused by compaction or erosion from wagon wheel or animal traffic may persist for >100 yr. This information underscores the importance that agricultural practices must minimize soil loss or compaction.
Natural Abundance of Nitrogen‐15 in a Forest Soil
Authors: Koba Keisuke , Tokuchi Naoko , Yoshioka Takahito , Hobbie Erik Alan , Iwatsubo Goro 
Published: July 2010

AbstractBecause of measurement difficulties, only a few studies on natural 15N abundance (δ15N) of inorganic N in forest soil have been pursued despite its importance for interpretations of plant δ15N signatures. To investigate stable N isotope ratios in inorganic N, the δ15N values and concentrations of total N, NH+4‐N, and NO−3‐N of forest mineral soils in four profiles were measured along a slope (altitude of 765–870 m) in a coniferous (Japanese red cedar, Cryptomeria japonica D. Don) forest in Japan. Generally, the δ15N values of total N, NH+4‐N, and NO−3‐N increased with increasing soil depth. The values of δ15N ranged from 1.0 to 6.8‰, 2.5 to 15.6‰, and −14.8 to 5.6‰ for total N, NH+4‐N, and NO−3‐N, respectively. Additionally, the δ15N values were different between NH+4‐N and NO−3‐N for each soil depth. Thus, it was concluded that the assumptions about inorganic N used in interpretation of plant δ15N values were valid. Moreover, on upper slope sites where soil inorganic N was predominantly NH+4‐N, the order of δ15N was generally total N > NH+4‐N > NO−3‐N for each depth, whereas the order of δ15N was NH+4‐N > total N > NO−3‐N on lower slope sites where NH+4‐N was less dominant as soil inorganic N and relatively high net nitrification rates were measured. Our results suggested that nitrification plays an important role in regulating δ15N in forest‐soil N.
Spatial Variability of Methane, Nitrous Oxide, and Carbon Dioxide Emissions from Drained Grasslands
Authors: van den Pol‐van Dasselaar A. , Corré W. J. , Priemé A. , Klemedtsson Å. K. , Weslien P. , Klemedtsson L. , Stein A. , Oenema O. 
Published: July 2010

AbstractEmissions of CH4, N2O, and CO2 from soils are the result of a number of biological and physical processes, each influenced by several environmental and management factors exhibiting spatial variability. This study aimed to assess the spatial variability and spatial dependence of CH4, N2O, and CO2 emissions and their underlying soil processes and properties from grasslands on drained peat soil (Terric Histosol). Emissions and possible controlling factors were measured at a field location in Sweden. Measurements were done on two adjacent sites on peat soil on two successive days for each site. Spatial variability was analyzed with trend analysis and variograms. Both sites consumed small amounts of atmospheric CH4, i.e., 0.03 and 0.05 mg CH4 m−2 d−1, and emitted N2O and CO2, i.e., 5 to 19 mg N2O m−2 d−1 and 4 to 6 g CO2 m−2 d−1. Spatial variability of emissions was high, with coefficients of variation of 50 to 1400%. Emissions either showed a spatial trend or were spatially dependent with ranges of spatial dependence of 50 to >200 m. However, spatial dependence of emissions showed differences between sites and short‐term temporal variability. Variograms of emissions and soil processes, which are partly biological in nature and have a high degree of inherent variability, should be interpreted with care.
Loblolly Pine Root Growth and Distribution under Water Stress
Authors: Torreano Scott J. , Morris Lawrence A. 
Published: July 2010

AbstractA rhizotron study was conducted to assess the relationship between soil water availability and shoot and root growth of loblolly pine (Pinus taeda L.) under conditions where O2 availability and mechanical resistance were considered not limiting. Relationships between soil water availability and (i) root growth rate, (ii) root distribution, (iii) growth periodicity, and (iv) above‐ and belowground allocation were evaluated under four watering regimes ranging from maintaining profile near field capacity (WK 1) to withholding moisture for 4 wk (WK 4). The final distribution of cumulative root growth was similar among watering treatments, even though root growth shifted downward with depth during the growing period due to water depletion in surface soils. Relative root elongation rates were found to be linearly related to soil water potential. The strength of this relationship was improved by considering only periods of active root growth. Reductions in above‐ and belowground growth were proportional among water‐restricting treatments. Stem volume and root growth in the driest treatments were reduced 46 and 41%, respectively, compared with the WK 1 cells, indicating that patterns of biomass allocation above and below ground were similar among treatments. In the absence of other limiting soil factors, flushes of root growth in this study were a function of relatively short‐term changes in soil water potential. Our results indicate that when maximum tree biomass is desired, management efforts in establishing pine should be aimed at reducing any restrictions to root growth during establishment.
Water Content Response of a Profiling Time Domain Reflectometry Probe
Authors: Ferré P. A. , Rudolph D. L. , Kachanoski R. G. 
Published: July 2010

AbstractWe designed a profiling time domain reflectometry (TDR) probe. The probe includes two short rods that measure through two parallel access tubes. Small diameter wires lead to the top of the measurement interval, limiting the sensitivity of the probe to the medium above the region of interest. Larger diameter target rods span the sample interval, leading to greater sensitivity of the probe to the medium surrounding the access tubes within the measurement interval. The probe sensitivity is further increased by sealing the access tubes and filling them with water. Six prototype probes built using readily available components showed a consistent sensitivity to the soil, receiving ≈25% of the total probe response from the medium around the access tubes in the sample interval. We tested three methods of field calibration of the probe. The calibrated profiling‐probe responses produce water‐content profiles comparable to those determined with a neutron probe during the advance of a wetting front.
Sorption of Imidacloprid on Soil Clay Mineral and Organic Components
Authors: Cox L. , Koskinen W. C. , Celis R. , Hermosin M. C. , Cornejo J. , Yen P. Y. 
Published: July 2010

AbstractSoil clay mineral and organic components have been shown to be responsible for sorption of many pesticides. This study assessed the influence of the different components of the clay fraction of five soils and model sorbents (montmorillonite, Fe oxide, and humic acid) and their binary and ternary associations on sorption of the insecticide imidacloprid (1‐[(6‐chloro‐3‐pyridinyl)‐methyl]‐N‐nitro‐2‐imidazoli‐dinimine). Sorption was very high on a clay fraction containing a high content of low‐laminar‐charge montmorillonite and relatively high organic C content. When organic matter of the soil clays was reduced by H2O2, sorption decreased; however, the sorption coefficient based on organic C (Koc) increased. The increase in Koc was greater on clays whose surface areas substantially increased after H2O2 treatment. This indicates a contribution of the surfaces of mineral components of the soil clay to sorption of imidacloprid. Imidacloprid sorbed on both montmorillonite and humic acid, whereas sorption on Fe oxide was very low. The sorption distribution coefficient, Kd, on montmorillonite increased from 15 to 180 when pH was decreased from 3.5 to 1.0, suggesting protonation of the ‐NH group of the imidazol ring. Sorption on binary and ternary associations of these model sorbents indicated that organic matter is the single most important component affecting sorption of imidacloprid, although there is some contribution of the mineral surfaces.
Sorption and Redox Activity of Cobalt Corrinoids on Hectorite
Authors: Kliewer K. E. , Morra Matthew J. 
Published: July 2010

AbstractHalogenated synthetic organic compounds are widespread contaminants of the environment; however, little is known concerning their potential dehalogenation by extracellular corrinoids. Our primary objective was to determine if corrinoids sorbed to soil colloids are redox active and thus viable electron transfer mediators of contaminant dehalogenation in reduced soils and sediments. Dicyanocobínamide, cyanocobalamin (vitamin B12), and aquocobalamin were sorbed onto Ca2+‐, K+‐, and Na+‐hectorite and sorption isotherms determined. Additional assessment of sorption reactions was performed using x‐ray diffraction (XRD) and infrared (IR) spectroscopy. Redox states of the sorbed corrinoids in hectorite suspensions were monitored using ultraviolet and visible (UV‐VIS) spectrophotometry. Corrinoid molecular size and charge, as well as the saturating cation, controlled corrinoid sorption. The XRD results indicated that Co corrinoids intercalated hectorite, expanding the basal spacing from 1.45 to 2.21 nm for Ca2+‐, 1.17 to 2.70 nm for K+‐, and 1.31 to 2.81 nm for Na+‐hectorite. The IR spectra of bound corrinoids yielded little information on binding mechanisms, but indicated that axial ligands remained intact. The central metal of bound corrinoids was reduced to Co(I) by Ti(III) and reoxidized to Co(III) by introduction of O2, thus demonstrating that redox activity of sorbed corrinoids was maintained and reversible. Microbially produced extracellular corrinoids may act as potential electron transfer mediators when in association with clays, possibly participating in the reductive dehalogenation of organic contaminants.