bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Closed, Well‐oxygenated System for the Determination of the Emission of Carbon Dioxide, Nitrous Oxide, and Ammonia
Authors: Fine P. , Feigin A. , Waisel Y. 
Published: July 2010

AbstractA simple closed system was set up for the measurement of CO2, N2O, and NH3 emission from soil samples kept under well‐oxygenated atmosphere. The system is an adaptation of a method suggested by Cornfield (1961a). Carbon dioxide is precipitated from the atmosphere as BaCO3, while O2 is generated from a BaO2 solution in equivalent amounts. With the aid of the proposed method, the simultaneous and quantitative determination of the mineral N forms in soils, of the gaseous N forms, and of CO2 may be performed even in well‐oxygenated conditions. Tests carried out in incubated soilsludge mixtures indicated that gaseous N forms may constitute a large fraction of the organic N ammonified. This may result in an underestimation of the mineralization potential of the organic N. Gas measurement may be needed where losses of N gases are likely or for the testing of the suitability of incubation techniques for the assessment of N mineralization capacities. The method is especially useful for the study of C and N dynamics in soil‐sludge mixtures.
Suspension Concentration Effects on Depositional Crusts and Soil Hydraulic Conductivity
Authors: Shainberg I. , Singer M. J. 
Published: July 2010

AbstractDepositional crusts form when turbid water infiltrates into soils. These crusts may reduce water infiltration rates. The effect of four concentrations of fine particles (0, ∼0.25, ∼0.5, and ∼1.0%) and two electrolyte concentrations (0.001 M and 0.005 M Cl‐) on water infiltration rate was studied. Infiltration and hydraulic conductivity (HC) of two nonsodic soils were not affected by leaching with the salt solutions because the electrolyte concentration in the percolating water was sufficient to prevent clay dispersion and swelling in the soils. The clay and silt that deposited at the soil surface decreased the water infiltration rate. The HC of the depositional crust was 2 and 3 orders of magnitude less than the HC of bulk soils in the 0.005 M and 0.001 M solutions, respectively. The rate of crust formation and the decrease in infiltration rate increased with increase in the solids concentration. Applying a −1.5‐kPa potential reduced crust HC but had no effect on soil HC. The effect of a potential was more pronounced on the crust deposited from the 0.005 M suspensions than on crust deposited from 0.001 M suspensions.
Effects of Dissolved Organic Carbon and Sulfate on Aluminum Mobilization in Forest Soil Columns
Authors: Evans Andrew 
Published: July 2010

AbstractA column study was conducted using a Cecil soil that was leached with various combinations of SO2‐4 and dissolved organic carbon (DOC), with the eluent pH adjusted to 4.6. Aluminum mobilization increased in the order SO2‐4 < DOC + SO2‐4 < DOC with Al being present primarily as Al in the 1000 to 2500 molecular aggregate range (MAR). The addition of SO2‐4 to the soil resulted in a reduction in DOC in the <1000 (MAR) with a corresponding increase in the 1000 to 2500 and 2500 to 5000 (MAR). Subsequent leaching with SO2‐4 after DOC treatment reduced Al mobilization. The number of pore volumes of eluent required for SO2‐4 break‐through decreased with elevated DOC levels in solution. Preliminary results suggest that SO2‐4 and organic species <1000 (MAR) compete for similar adsorption sites.
Soil Disturbance by Skyline Yarding vs. Skidding in a Loamy Hill Forest
Authors: Miller James H. , Sirois Donald L. 
Published: July 2010

AbstractSoil disturbance was assessed on harvested units of mature southern pines (Pinus spp.), where a part of each unit was logged with a cable skyline system and a part with rubber‐tired ground skidders. Effects of the two methods of harvesting were studied by aerial and ground surveys. Cable yarding required 2% less acreage in landings than skidding, and yarding corridors occupied 12% less area than skid trails. Physical and chemical analyses of surface soils (upper 15 cm) showed that loam soils with clay subsoils were most severely affected by the displacement of topsoil after both methods of logging. On 8 to 14% of both logged areas, harvesting activities resulted in significant reductions in organic matter, available moisture holding capacity, and available P, Ca, and K. Silt loam soils were severely compacted by cable yarding in the corridors that consistently ran upslope creating the greatest erosion potential. It is concluded that the carefully planned use of skyline cable systems would minimize the area affected by severe soil disturbance and should be considered for future harvesting in this Jocale.
A Freezing Technique for Sampling Skeletal, Structureless Forest Soils
Authors: Froehlich H. A. , Miles D. W. R. 
Published: July 2010

AbstractA technique was developed to take large undisturbed samples in forest soils with high coarse‐fragment content. Each sampling site was wetted with water, a metal pin was driven into and carefully removed from the soil, and liquid N2 was poured into the resulting hole. A frozen sample up to 200 mm in diam and 450 mm deep could be excavated and transported frozen to the laboratory. This sampling technique allowed measurement of bulk density, particle size distribution, and organic matter characteristics. The large size of the samples permitted sampling of soils with coarse fragments up to 85 mm in diam.
Soil‐water Properties as Affected by Twelve Annual Applications of Cattle Feedlot Manure
Authors: Sommerfeldt T. G. , Chang C. 
Published: July 2010

AbstractA long‐term study was set up to determine the effects of annual applications of manure, at rates in excess of the recommended, on a Dark Brown Chernozemic (Typic Haploborolls) soil. Cattle (Bos taurus) feedlot manure was applied at 0, 30, 60 and 90 Mg ha−1 to nonirrigated and 0, 60, 120, and 180 Mg ha−1 to irrigated land at the Lethbridge Research Station. Soil‐water properties of the soil at 0‐ to 15‐ and 15‐ to 30‐cm depths, as affected by the manure, are reported. In the surface 15 cm of soil, the mean volume of plant‐available water retained by the soil between 20 and 1500 kPa tension decreased with increasing rates of manure on both the nonirrigated and irrigated blocks of land. The saturated hydraulic conductivity of the soil cores and the infiltration rate of the soil in the field were unaffected by the applied manure.
Influence of Spatially Variable Soil Hydraulic Properties on Predictions of Water Stress
Authors: Anderson S. H. , Cassel D. K. , Skaggs R. W. 
Published: July 2010

AbstractModels are often used to predict drainage system effects on crop production. Variability of soil hydraulic properties on predictions made by many models have not been evaluated. This study evaluated several methods for predicting water transport properties and corn (Zea mays L.) stress as influenced by variable soil hydraulic properties in a field of Portsmouth sandy loam (Typic Umbraquults). Upflux, drainage volume, and infiltration parameters as functions of water table depth were predicted using hydraulic conductivity and soil water retention functions for three soil horizons measured at 150 locations in a field. Crop stress due to both deficient and excess soil water conditions and relative crop yield were estimated using DRAINMOD, a water management simulation model, for three selected methods of averaging soil property inputs. Small differences existed among the three approaches for the 30‐yr average relative corn yield. Large differences in relative corn yield occurred in dry years indicating that the variability of the soil properties was important to consider in predicting crop stress during relatively dry years. More information for the field soil‐drainage response was obtained using the individual locations method which allowed soil property inputs to vary from location to location at each of the 150 points in the field. However, the field averages approach is more practical because fewer data are required to perform the necessary computations and only a 3% difference in the 30‐yr relative yield resulted between the individual location and field average methods.
Estimating Soil Water Content Using Cokriging
Authors: Yates S. R. , Warrick A. W. 
Published: July 2010

AbstractUsing cokriging estimates, and estimation variances of the gravimetric moisture content (GMC) were made using one and two additional random functions: the bare soil surface temperature and the percent sand content. The semivariograms and cross‐semivariograms were obtained as well as the sample correlation between the GMC and the auxiliary functions. Various measures of the differences and quality of the estimates for kriging and cokriging were calculated and compared on the basis of the sample correlation and whether the auxiliary random functions were over‐sampled with respect to the GMC. The average estimation variance for cokriging compared to kriging was reduced for all levels of absolute sample correlation considered (i.e., 0.15‐0.83). The mean sum of squares error between the actual and estimated values obtained by the jack‐knifing technique was found to be lower for cokriging when compared to ordinary kriging when highly correlated auxiliary random variables were used but could be greater than that of ordinary kriging for less correlated auxiliary variables. It was found that the additional complexity of cokriging may be justified when the magnitude of the sample correlation exceeded 0.5 and the auxiliary functions were over‐sampled with respect to the GMC.
Steady Three‐dimensional Absorption in Anisotropic Soils
Authors: Philip J. R. 
Published: July 2010

AbstractExact solutions are given for steady absorption from spheroidal cavities into soils with axisymmetric anisotropy independent of moisture potential. The needle, sphere, and disc are special cases. Apart from their direct relevance to systems with gravity negligible, our results yield the leading terms of expansions describing steady infiltration into such soils for small and moderate values of the dimensionless cavity length. The effectively wetted region is a spheroid with aspect ratio µ, where µ2 is the anisotropy. The analysis suggests that, in anisotropic soils, vertical conductivity influences the capillary component of flow much more strongly for disc permeameters than for borehole permeameters. Generalizations of the problem solved in detail involve (i) inequality of the three conductivity principal components, (ii) cavity axes skew to conductivity axes, (iii) ellipsoidal cavities. Any one, combination of two, or all three, of these generalizations leads to essentially the same mathematical problem with the solution expressible in terms of the incomplete elliptic integral of the first kind.
Solute Transport Through a Stony Soil
Authors: Schulin R. , Wierenga P. J. , Flühler H. , Leuenberger J. 
Published: July 2010

AbstractMovement of tritium and Cl‐ was studied through undisturbed, unsaturated columns of a Rendoll soil (Eutrochreptic rendoll) containing between 50 and 55% by volume of stones. The columns, 30 cm in diameter and 50 cm long, were leached at a steady flow rate varying from 0.16 to 41 cm/d. Breakthrough curves from these stony soils were smooth and mostly symmetrical, especially for the lowest flux. Based on an analysis with the classical two‐parameter convection‐dispersion equation, it was found that the dispersion coefficient was linearly related to pore water velocity with an average dispersivity of about 4 cm. The difference between the retardation factors for Cl‐ and tritium averaged 0.16 pore volumes. Using a four‐parameter transport equation with exchange between mobile and immobile liquid phases, an immobile water fraction of 15% was found, independent of the leaching rate. The four‐parameter model provided no better fit to the experimental data than the two‐parameter model for the lowest flux and only slightly better fits for all the other cases. This indicates that nonequilibrium conditions between mobile and immobile phases were of minor importance in modeling solute transport through this stony soil.
Populations of Bradyrhizobium japonicum in Fields Cropped with Soybean‐Rice Rotations
Authors: Weaver R. W. , Morris D. R. , Boonkerd N. , Sij J. 
Published: July 2010

AbstractThe population density of Bradyrhizobium japonicum in soil, before planting, largely determines the potential yield increase of soybean (Glycine max L. Merrill) due to inoculation. Soybean is cultured in rotation with rice (Oryza sativa L.) in the paddy rice belt of the southern USA. Nineteen fields were sampled to determine the influence of paddy rice culture on the population of B. japonicum. Populations in fields following soybean were approximately 1 × 104 bradyrhizobia g−1 soil. Growing rice after soybean did not reduce the population of bradyrhizobia. Apparently the bradyrhizobia were able to survive the conditions in saturated soil for several months.
Susceptibility to Compression of a Clay Loam Haplaquoll
Authors: Culley J. L. B. , Larson W. E. 
Published: July 2010

AbstractThe objective of this study was to determine the compressibility of a poorly drained clay loam soil cropped to corn (Zea mays L.) with moldboard plowing as primary tillage (CN) or with no tillage (NT). Undisturbed cylindrical cores (100 cm3)obtained from planter‐tracked (WT) and untracked (NWT) interrows just prior to harvest, were subjected to uniaxial compression after being equilibrated at soil moisture potentials (ψ) of −5, −10, −20, and −40 kPa. The precompression (over‐consolidated) and virgin compression regions were isolated by plotting bulk weight volume (v) against the logarithm of applied pressure. The breakpoint or precompression pressures (σp), which separated the over‐ and virgin compression regions, were determined using a statistical procedure. There was no apparent σp for cores from CN‐NWT interrows with ψ at or above −10 kPa. Tracking of tilled interrows resulted in the presence of over‐consolidated regions at all moisture potentials. Virgin compression indices (slopes) decreased in the order CN‐NWT > CN‐WT > NT‐NWT > NT‐WT. A highly significant correlation (p < 0.01) was obtained between σp and the undrained strength as measured by the fall‐cone device.
Surface Charge Characterization and Soil Solution Composition of Four Soils from the Southern Piedmont in Georgia
Authors: Gillman G. P. , Sumner M. E. 
Published: July 2010

AbstractFour soils (Cecil, Typic Hapludult; Davidson, Rhodic Paleudult; Dyke, Typic Rhodudult; and Townley, Typic Hapludult) from the Southern Piedmont in Georgia, which have received large applications of gypsum, as well as soils from control plots, have been characterized with respect to their surface charge properties. The soils have variable charge character to varying degrees, but added gypsum has not affected fundamental surface charge properties such as cation and anion exchange capacities. The addition of Ca via gypsum has, however, altered the proportion of exchangeable basic and acidic cations. Analysis of extracted soil solution showed that Ca from gypsum can move rapidly through the profile, causing Mg to be displaced from exchange sites and therefore to be susceptible to leaching. A distinction is made between total cation exchange capacity and basic cation exchange capacity, and their significance with respect to exchangeable cations present is discussed.
A New Technique for Assessment of Reversibly Adsorbed Phosphate
Authors: van der Zee S. E. A. T. M. , Fokkink L. G. J. , van Riemsdijk W. H. 
Published: July 2010

AbstractA new desorption technique for soil phosphate is described, in which Fe oxide coated filter paper is used as an “infinite” sink for P. This technique is applied to study desorption kinetics for nine sandy soils. The desorption can be explained with a simple Lang‐muir kinetics model. The mean value of the desorption rate constants found is kd = 0.2 ± 0.08 h−1. The estimated errors that are due to re‐equilibration during the experiments are less than experimental error. The amounts of P desorbed with the new technique, Pi, are compared to the amounts that desorb if a conventional dilution technique, Pw, is used. The new technique desorbs more P than the conventional method (Pi > Pw). By comparing Pi with oxalate‐extractable P (Pox) it is evident that reversibly adsorbed P rarely exceeds one‐third of Pox. Differences between the soils can be explained in terms of the oxalate‐extractable amounts of Fe and Al.
Effects of Soil Acidification on Chemical and Mineralogical Properties of a Limed Soil
Authors: Lietzke D. A. , Peterson D. V. 
Published: July 2010

AbstractTwo soil acidulents were compared for their effects on soil chemical and mineralogical properties. Aluminum sulfate [Al2(SO4)3 · 18 H2O] powder was applied at rates of 0.13, 0.26, 0.52, and 1.05 kg m−3 (7.5, 15.0, 30.0, and 60.0 g per pot, respectively). Elemental S powder was added at rates of 0.03, 0.06, 0.13, and 0.26 kg m−3 (1.9, 3.8, 7.5, and 15.0 g per pot, respectively). Sawdust was incorporated into the soil at rates of 0, 20, 40, and 60 m3 m−3 (% by volume). The soil used in this experiment was a previously limed sandy loam surface from a Typic Hapludult with an initial pH of 6.2. On a mass basis, approximately eight times as much Al2(SO4)3·18 H2O as elemental S was needed to cause a two‐unit decrease in soil pH. The acidity produced by S maintained low pH longer than Al2(SO4)3·18 H2O. Extractable levels of Ca and Mg in the highest acidulent treatments were approximately double that of the controls at the conclusion of the experiment. This is a probable response to lime particles from a previous liming being dissolved by acids. Extractable K, because of destruction of illitic clay minerals, was significantly higher in the S treatments than in the Al2(SO4)3 treatments or controls. Extractable Al levels were greater than the controls only at higher rates of both acidulents. Extractable Al levels at a given pH were higher in the Al2(SO4)3‐treated soils than in those treated with S. Destruction of clay minerals, including gibbsite, kaolinite, and hydroxy interlayered vermiculite were evident in the highest S treatment, even though both the Ca/Mg and K/NH4 cation exchange capacity values increased when compared to the controls. Aluminum sulfate had little effect on clay mineral stability when compared to the controls, and may have increased the heat stability of K saturated hydroxy interlayered vermiculite.
Interactions Among Vesicular‐Arbuscular Mycorrhizae, Soil, and Landscape Position
Authors: Day L. D. , Sylvia D. M. , Collins M. E. 
Published: July 2010

AbstractThe interrelationships among mycorrhizae, soil, and landscape position were investigated for a bahiagrass pasture (Paspalum notatum Flugge) in northern Florida. A significant effect of landscape position was found for spore number, root colonization, root length, the ratio of Acaulospora and Glomus to Gigaspora spores, and number of spores per centimeter of colonized root. Root colonization and propagule numbers were least in the most erosive positions (shoulder and backslope) of the landscape. This implied that the population density of vesicular‐arbuscular mycorrhizae (VAM) fungi may be reduced by soil erosion even if erosion is not severe enough to affect plant cover. The pattern of soils across the landscape influenced the distribution of genera of VAM fungi; soils in footslope positions had sandier surface textures as a consequence of erosional/depositional processes and favored higher populations of Gigaspora than of Acaulospora and Glomus.
Effects of Phosphorus and Acidity on Levels of Silica Extracted from a Palouse Silt Loam
Authors: Brown T. H. , Mahler R. L. 
Published: July 2010

AbstractConcentrations of Si found in soil solutions are affected both by soil pH and by P availability. Consequently, it was hypothesized that the heavy local use of NH4‐based N fertilizers and of P fertilizers could greatly affect the Si chemistry of soils from the Palouse area of northern Idaho. The objectives of this study were to evaluate the effects of P and acidity on concentrations of Si in water extracts from Palouse silt loam (fine‐silty, mixed, mesic, Pachic Ultic Haploxerolls) soils and to correlate observed effects with possible mechanisms responsible for Si solubility, Soil samples were equilibrated with acid and with P for periods of 0.2 to 150 d in 0.02 M CaCl2 solutions. Increased acidity and the presence of P were both found to increase the concentrations of Si in solution above control levels. These data appear to be additive, suggesting that the mechanisms responsible for increasing solution Si levels for the respective treatments are different. It is postulated that acidity increases Si concentrations in solution by directly affecting the solubility of compounds containing Si, and that P oxyanions compete directly with Si compounds for specific sorption sites.
A Zinc Soil Test Calibration Based upon Mehlich 3 Extractable Zinc, pH, and Cation Exchange Capacity
Authors: Junus M. A. , Cox F. R. 
Published: July 2010

AbstractThe soil Zn critical level generally decreases as organic matter content increases. Certain other properties, notably cation exchange capacity (CEC) and optimum soil pH, also vary with organic content. These properties and Mehlich 3 extractable Zn (M3Zn) were used to calibrate a Zn soil test from greenhouse and field data. Soils were collected from four lime treatments in field experiments conducted on six Ultisols. An Inceptisol and a Histosol were also sampled and four lime treatments established, providing a range in pH and organic matter content. Three levels of Zn as ZnSO4 · 7H2O were added to each soil. Soybeans [Glycine max (L.) Merr., cv. Centennial] and corn (Zea mays L., cv. Pioneer 3369A) were grown successively in the greenhouse, each for 5 weeks. Mehlich 3 extractable Zn decreased with an increase in soil pH on only one of the eight soils, but Zn concentration in plants grown on all soils decreased with an increase in soil pH. Mehlich 3 extractable Zn alone accounted for little of the variation in the plant Zn concentration of the two crops. Including soil pH and CEC in the model increased the R2 to 0.56 and 0.50 for soybeans and corn, respectively. When the squared and first‐order interaction terms of these variables were considered, the R2 increased to 0.76 for soybeans and 0.66 for corn. For corn grown in the field, these same variables were found to be important in Zn soil test calibration. The form of the regression equation proved to be illogical, however, because the range in soil properties was not sufficient to produce a reliable prediction equation. Regression equations from the greenhouse were then adjusted to predict the leaf Zn concentrations of crops grown in the field. For corn, an equation that gave reasonable estimates of leaf Zn concentration in the field was developed. This equation may be used to interpret the need for Zn fertilization over a continuum of extractable Zn concentration, pH, and CEC in soils.