bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery of Compacted Soils in Mojave Desert Ghost Towns
Authors: Webb Robert H. , Steiger John W. , Wilshire Howard G. 
Published: July 2010

AbstractResidual compaction of soils was measured at seven sites in five Mojave Desert ghost towns. Soils in these Death Valley National Monument townsites were compacted by vehicles, animals, and human trampling, and the townsites had been completely abandoned and the buildings removed for 64 to 75 yr. The soils studied (generally sandy, mixed, Typic Calciorthids) were derived from granitic or volcanic alluvium at elevations from 1310 to 1730 m. Compaction measurements in the townsites, including penetration depth, penetration resistance, bulk density, and peak shear stress, indicated that only one site had completely recovered to ambient soil conditions after 75 yr. Recovery times extrapolated using a linear recovery model ranged from 80 to 140 yr and averaged 100 yr. The recovery times were related to elevation, suggesting freeze‐thaw loosening as an important factor in ameliorating soil compaction in the Mojave Desert.
Spatial Dependence and Interpolation of Soil Properties in West Sumatra, Indonesia: I. Anisotropic Variation
Authors: Trangmar B. B. , Yost R. S. , Uehara G. 
Published: July 2010

AbstractSpatial and temporal interaction of soil‐forming factors and processes determine the distribution of soil properties within the landscape. This study relates anisotropic spatial dependence of particle size fractions, pH and 25% HCl‐extractable P to directional differences in the main soil‐forming factors in Sitiung, West Sumatra, Indonesia. Linear geometric anisotropic models were fitted to pooled directional semivariances for each of these properties. Directions of maximum variation coincided with the main southwest to northeast axis of volcanic tuff fallout, deposition of alluvium and the general sequence of soil weathering in the region. Anisotropy ratios ranged from 1.5 for subsoil pH to 5.2 for subsoil HCl‐P. Topsoil textural components and pH were more variable than in subsoils, having larger sample variances and larger anisotropy ratios. Punctual kriging of topsoil sand content using the linear geometric anisotropic model resulted in low estimation variances in densely sampled areas where weighting of neighbor samples by direction as well as distance took most effect. Quantitative analysis of anisotropic spatial dependence of soil properties can aid interpretation of soil genesis. Estimates of anisotropic spatial dependence can also be incorporated into kriging interpolation for optimal, unbiased spatial estimation with minimum variance.
Boron Adsorption and Silicon Release by the Clay Minerals Kaolinite, Montmorillonite, and Illite
Authors: Goldberg Sabine , Glaubig R. A. 
Published: July 2010

AbstractBoron adsorption behavior on the clay minerals kaolinite, montmorillonite, and illite was investigated. Adsorption increased at low pH, exhibited a peak in the pH range 8 to 10, and decreased at high pH. It was assumed that B adsorbs by means of a ligand exchange mechanism with aluminol groups at the edges of the clay particles. The constant capacitance model was able to describe B adsorption on kaolinites over the entire pH range studied (3–12), using only one adjustable parameter: the boron surface complexation constant. The model was able to fit B adsorption on montmorillonites and illites using three adjustable parameters; however, the chemical significance of some of the surface complexation constants is uncertain. Silicon release to solution increased in the order: kaolinite ∦ illite < montmorillonite and exhibited a minimum in the pH range 8 to 9. Boron adsorption on kaolinites was reduced only slightly in the presence of added silicate despite considerable silicate adsorption. Boron adsorption on montmorillonites was unaffected by the presence of added silicate. It is suggested that B and silicate adsorb on specific sites and that little anion competition occurs.
Speciation of Hydroxy‐Aluminum Solutions by Wet Chemical and Aluminum‐27 NMR Methods
Authors: Bertsch Paul M. , Layton W. John , Barnhisel R. I. 
Published: July 2010

AbstractPartially neutralized Al solutions with OH/Al molar (ñ) ratios ranging from 0.25 to 2.5 were studied employing 27Al nuclear magnetic resonance spectroscopy and the ferron‐timed colorimetric assay. The monomeric Al concentrations (Ala) estimated by the ferron assay were consistently higher than the actual concentration determined by NMR spectroscopy. The differences between the methods indicate the presence of a small polymer which reacts rapidly with ferron and is erroneously assigned to the monomeric Al fraction. The polymeric Al component (Alb) estimated by the ferron method could be partitioned into a more rapidly reacting fraction (≤1 h) and a slowly reacting fraction (>1 h). The amount of Al associated with the rapidly reacting polymeric fraction corresponded to the amount of [AlO4 Al12(OH)24(H2O)12]7+ polymer directly determined by NMR spectroscopy. The slower reacting component of the Alb fraction is believed to be a polymer of the hexameric ring morphology. Direct NMR measurements provided evidence for specific adsorption of Al13 to a cation exchange resin and differential precipitation kinetics of this polymer with added sulfate. These data indicate that characterizing hydroxy Al solutions without direct measurements can lead to erroneous interpretations concerning the distribution between monomeric and polymeric Al and the nature and types of polymeric Al present.
Anisotropy of a Fragipan Soil: Vertical vs. Horizontal Hydraulic Conductivity
Authors: Dabney S. M. , Selim H. M. 
Published: July 2010

AbstractUndisturbed core samples were obtained in vertical and horizonal directions from surface and subsurface horizons of an Olivier silt loam (Aquic Fragiudalfs, fine‐silty, mixed, thermic) in order to test for anisotropy. Saturated hydraulic conductivity, bulk density, penetrometer resistance, and volumetric moisture content at soil matric potential of 30 J kg−1 were measured. Hydraulic conductivity values within the Ap did not differ in horizontal and vertical sampling directions. However, within the Btx1 horizon, measured conductivity values were three times greater in vertical than in horizontal directions. This was attributed to the primarily vertical orientation of flow‐restrictive zones within the fragipan. Bulk density and moisture content differed between surface and subsurface horizons, but were not influenced by direction of core sampling. Penetrometer resistance did not differ between horizons or sampling direction, but was significantly greater in brown than in grey areas of the fragipan. The results of this study have relevance to models of soil water flow and the sampling methods described should be applicable to testing for anisotropy in other soils.
Method of Estimating the Travel Time of Noninteracting Solutes Through Compacted Soil Material
Authors: Horton R. , Thompson M. L. , McBride J. F. 
Published: July 2010

AbstractThe pollutant travel time through compacted soil material (i.e., when a pollutant introduced at the top first appears at the bottom) cannot be accurately predicted from the permeability (saturated hydraulic conductivity) alone. The travel time is also dependent on the effective porosity of the material; i.e., the portion of the total porosity that contributes significantly to fluid flow. Once permeability and effective porosity are determined for a selected material, the travel time of noninteracting pollutants through specified thicknesses of compacted material at specified hydraulic gradients can be predicted easily. Pollutant travel time is directly proportional to effective porosity and thickness of a compacted layer and inversely proportional to permeability and hydraulic gradient. This paper presents a straightforward method of determining the effective porosity of compacted soil materials. The determination of effective porosity is based upon the total porosity and the spread on a log scale in the pore sizes of a compacted sample. The total porosity is calculated from measurements of bulk and particle density. Pore size distribution information is obtained from the cumulative porosity curve of the sample as measured by a mercury‐intrusion porosimeter. Once the total porosity and pore size distribution information are obtained for a particular sample, the effective porosity can be determined directly by using a graphical relationship. This paper also compares measured and predicted solute breakthrough times for three compacted soil materials. Predicted travel times through compacted samples of glacial till, loess, and paleosol materials were reasonably close to measurements of CL‐ travel time.
Stratigraphy and Genesis of Polygenetic Soils on the Illinoian Till Plain of Southwestern Ohio
Authors: Ransom M. D. , Smeck N.E. , Bigham J. M. 
Published: July 2010

AbstractThree pedons each of Clermont (Typic Glossaqualfs) and Avonburg (Aeric Fragiaqualfs) soils were investigated on the Illinoian till plain of southwestern Ohio in order to evaluate parent material stratigraphy and to determine if paleosols were substantially altered following burial by a thin mantle of loess. The relationship between fragipan development and paleosol properties was also examined. The soils were found to have formed in 57 to 69 cm of Late Wisconsinan (Peoria) loess overlying a composite Early Wisconsinan and Sangamon paleosol. The Sangamon paleosol, which was most strongly developed at approximately 150 to 200 cm, was formed in Illinoian till. The material from about 70 to 140 cm consisted of a mixture of Early Wisconsinan loess and Illinoian till with till characteristics dominating. Evidence for a mixed zone in the upper paleosol included (i) a higher silt content than the lower paleosol, (ii) a maximum in elemental Ca in the total silt fraction, and (iii) an abundance of pedotubules in up to 50% of some horizons suggesting that mixing was caused by bioturbation. Modification of the paleosols has occurred as evidenced by recharge with secondary carbonates and bases leached from the overlying loess. A fragipan was identified in only one Avonburg pedon that had a clay content of 27% in the upper part of the paleosol as compared to 31 to 38% for the other pedons. Fragipans appear to have formed in these soils only if the clay content of the upper part of the paleosol is currently less than about 30%.
Soils with Bx Horizons in the Upper Coastal Plains of South Carolina
Authors: Smith B. R. , Callahan L. L. 
Published: July 2010

AbstractSoils with firm, dense Bx horizons are extensive in the Upper Coastal Plains including the Sandhills of Georgia, North Carolina, and South Carolina. The Bx horizons are slightly brittle to brittle, but prisms with bleached, vertical faces are often weakly developed or absent. Three pedons of a series representative of these soils were studied in detail to characterize the soils, to determine if they have fragipans, and to determine if they are properly classified. Particle size distribution data show that the Bx horizons also meet the criteria of argillic horizons, as do many fragipans. Bulk densities are high in the Bx horizons. Free Fe oxide contents are highest in the Bt or Bx horizons, just as are clay contents. Clay mineralogy in the surface horizons is predominately hydroxy‐Al interlayered vermiculite (HIV) and kaolinite with substantial amounts of gibbsite. HIV and gibbsite decrease and kaolinite increases with depth. Micromorphological examinations reveal dense packing of quartz skeleton grains with a mixture of clay minerals and Fe oxyhydroxides and very few voids in the Bt, Bx, and C horizons. Yellow illuviation argillans and red illuviation ferriargillans are fairly common in the Bt and Bx horizons. Some segregation of Fe oxyhydroxides has occurred in the soils. Brittleness of the Bx horizons is restricted to the reddish‐colored material. This indicates that weak cementation by Fe oxyhydroxides in the presence of clay minerals is at least partly responsible for the brittleness. The Bx horizons are brittle in approximately 45 to 50% of the volume and have many of the properties of fragipans. The establishment of a Fragic subgroup of Hapludults is proposed for these and similar soils.
Three‐Minute Analysis of Chloride, Nitrate, and Sulfate by Single Column Anion Chromatography
Authors: Barak Phillip , Chen Yona 
Published: July 2010

AbstractAccepted techniques of single column ion chromatography of inorganic anions were extended to separation of chloride, nitrate, and sulfate using 15 mM phthalic acid as an eluent, permitting reduction of column length to 30 mm and thereby reducing analysis time to three min. Using a 50 µL sample loop, detection limits were 0.05 mmolc L−1 and coefficient of variation values ranged from 0.8 to 1.7% using peak height measurements and 0.8 to 8.1% using peak area measurements. This configuration is appropriate for routine analysis of soil water extracts and ground water.
Ion‐selective Electrode Determinations of Exchangeable Potassium in Soils
Authors: Farrell R. E. , Scott A. D. 
Published: July 2010

AbstractProcedures using ion‐selective electrodes (ISEs) for the accurate determination of NH+4 ‐and Ba2+‐exchangeable K+ in soil extracts are described. The exchangeable K+ in 30 soil samples was extracted with neutral solutions of 1.0 M NH4OAc and 0.5 M BaCl2 and determined by atomic absorption spectrometry (AAS) to establish the K+ levels sought with the electrodes. Potentiometric measurements were then made with electrochemical cells consisting of either a valinomycin‐based K+‐selective electrode (VKE) or a cationic glass‐membrane electrode (CGE) and a double‐junction sleeve‐type reference electrode assembly with a saturated LiOAc salt bridge. The electrochemically analyzed solutions (1:5 extract/water dilutions) had a common ionic strength and a pH near 7 or a LiOH‐adjusted pH of 11.6. A comparison of the AAS values for the Ba2+‐ and NH+4‐exchangeable K+ demonstrated the feasibility of using either extractant for an evaluation of ISE methods. Interferences from NH+4 and Li+ limited the use of the CGE to the neutral BaCl2 extracts, where it yielded exchangeable K+ values that were only poorly correlated (r = 0.655) with those obtained by AAS. However, the Ba2+‐exchangeable K+ values obtained with the VKE were highly correlated (r = 0.983) with and not significantly different (α = 0.05) from those obtained by AAS with the neutral extracts and even more so with solutions at pH 11.6 (r = 0.998; α = 0.01). Accurate direct‐potentiometric determinations of the exchangeable K+ in the NH4OAc extracts were not feasible, even at pH 11.6. But the NH+4‐exchangeable K+ values obtained with the VKE and a modified standard additions technique were highly correlated (r = 0.987) with and not significantly different (α = 0.05) from those obtained by AAS.
Spectrofluorometric Investigation of Trace Metal Complexation by an Aqueous Chestnut Leaf Litter Extract
Authors: Blaser P. , Sposito Garrison 
Published: July 2010

AbstractFluorescence spectroscopy was investigated as a method for quantitating trace metal complexes with the organic ligands in a water extract of chestnut (Castanea sativa L.) leaf litter. Copper(II) and aluminum(III) were selected as environmentally significant metals with which to characterize the method as applied to the leaf litter extract. Solutions of Cu or Al mixed with the extract exhibited fluorescence that decreased in relative intensity as the total metal concentration and/or the pH increased. Data were obtained in the pH range 5 to 8 for total Cu concentrations up to 160 mmol m−3 and in the pH range 4 to 8 for total Al concentrations up to 100 mmol m−3. The fluorescence intensity data for Cu were comparable to those obtained in previous studies for solutions of Cu and soluble humic materials. A conventional equation was used to calculate an overall stability coefficient for metal complexation by the leaf litter extract. The pH‐dependence of this stability coefficient was modeled mathematically in terms of pH‐independent conditional stability constants through a new application of the Scatchard quasiparticle model. The quasiparticle species Cu(OH)nH0.9L (n = 0 or 1; L = organic ligands) were sufficient to model the Cu data with the two pH‐independent conditional stability constants, cβ0/0.9 = 1012.6 and cβ1/0.9 = 105.3. For the Al data, the conditional stability constants cβ0/0 = 108.55 and cβ2/0 = 10−1.8 were obtained for the quasiparticle species Al(OH)nL (n = 0 or 2). These stability constants can be used in computer speciation programs to estimate organic complexation of Cu(II) or Al(III) by the leaf litter extract, but otherwise have no molecular chemical significance.
Organic Matter Leaching as a Component of Carbon, Nitrogen, Phosphorus, and Sulfur Cycles in a Forest, Grassland, and Gleyed Soil
Authors: Schoenau J. J. , Bettany J. R. 
Published: July 2010

AbstractThe profiles of a forest (Typic Cryoboralf), grassland (Aridic Haploboroll), and gleyed (Argiaquoll) soil were examined to assess the role of organic matter leaching in determining organic matter composition in genetic horizons of soil profiles. An increasing proportion of NaOH extractable C, N, P, and S was found in the fulvic acid (FA) fraction as depth in the profiles increased, suggesting that fulvic acids produced in biologically active surface horizons have been translocated to B and C horizons by percolating water. The fulvic acid in B and C horizons was highly enriched in N, P, and S relative to the humic acid and fulvic acid in surface horizons, indicating that the organic matter being translocated downward is richer in N, P, and S than fractions not susceptible to leaching. Leaching of nutrient‐rich organic matter thus provides a valid explanation for the observed narrowing of soil organic matter C/N, C/P, and C/S ratios with increasing depth. The lowest HA/FA ratios coincided with the depth of CaCO3 accumulation, revealing a possible role of Ca and other basic cations in precipitation of organic matter from solution. Of the four elements studied, P appeared to be the most susceptible to deep leaching in the organic form. This is believed to reflect the predominance of organic P in the low molecular weight, mobile fraction of soil organic matter. Loss of labile, nutrient‐rich organics from surface horizons by leaching may be important in controlling element turnover rates and nutrient distribution within soil profiles. It may also represent a major nutrient export mechanism.
Spatial Variation of Soil Properties and Rice Yield on Recently Cleared Land
Authors: Trangmar B. B. , Yost R. S. , Wade M. K. , Uehara G. , Sudjadi M. 
Published: July 2010

AbstractCrop yields on cleared forest land of the humid tropics are often highly variable due to spatial heterogeneity of soil properties. This study aimed to characterize spatial variation of soil chemical properties and yield components of upland rice (Oryza sativa) on a 0.1‐ha field of recently cleared land in West Sumatra, Indonesia. Plants were taller, stover and grain yields higher on sites where forest rash had been piled and burned, compared to the surrounding soils and other sites where topsoils had been removed. This pattern was largely caused by lower levels of Al saturation and higher concentrations of exchangeable cations in burned sites compared to other parts of the plot. The range of spatial dependence for soil acidity and exchange characteristics was 3 to 4 m, but increased to 7 m for organic C, total N, and extractable P. Semivariograms of crop components were better structured and had longer ranges (up to 20 m) than the soil chemical properties. Block kriging gave more precise local estimation of grain yield at unsampled locations than terrain unit means because it utiliized the inherent structure of variation determined from quantitative spatial analysis of observed values. Block kriged values of grain yield ranged from 11 to 355 g/m2 with estimation standard deviations ranging from 9 to 24 g/m2, depending on distance of interpolated cells from the 122 sample locations.
Silty Deposits of a Low, Pleistocene‐age Terrace in Eastern Arkansas
Authors: West L. T. , Rutledge E. M. 
Published: July 2010

AbstractA segment of Terrace Qtb3 of the Western Lowlands of Arkansas was transected to determine if the silty material capping the terrace is loess or silty alluvium. Four sites along an east‐west transect were sampled to test the hypothesis that the material is loess with its source area immediately east of the terrace segment. Three deposits dominated by silts were identified at each site by morphology, fine‐earth and clay‐free particle size distribution, and by distribution of total Ca and K in the coarse silt fraction. The lowest of the silty deposits was identified as alluvium by its sand contents and stratification in the lower part. The morphology of the upper two deposits was similar to that of loess on other terraces in the area. However, relationships between clay‐free particle size distribution and log distance from the proposed source area were not those expected for loess. Thus, these two deposits are also interpreted as silty alluvium. Geomorphic relationships indicate that the terrace is younger than Illinoian, but no minimum age can be deduced from current data.
Seed Zone Soil Temperature and Early Corn Growth with Three Conservation Tillage Systems
Authors: Al‐Darby A. M. , Lowery B. 
Published: July 2010

AbstractDetailed data are needed to quantify the effect of conservation tillage (CT) on corn (Zea mays L.) emergence and early growth in the Northern Corn Belt. Corn was grown using three CT systems: till‐plant (TP), chisel (CH), and no‐till (NT) and conventional moldboard plow (CN) on a Griswold silt loam soil (Typic Argiudoll) during the 1982 to 1984 growing seasons. Soil temperature at the seed depth (5 cm) was measured hourly. Daily means and cumulative growing degree days (GDD) based on seed zone temperatures were calculated. Corn emergence was monitored. Leaf area and dry matter per hectare were measured at different growth stages. Relative growth rates (RGR) were calculated from daily measured plant heights. Soil temperature at the 5‐cm depth ranked CN > TP > CH > NT. Initial corn emergence rates with the NT system were depressed compared to CN; the emergence rate ranked CN > TP = CH > NT. However, time to 100% emergence was delayed by 8, 2 to 3, and 2 d for NT compared to CN in 1982, 1983, and 1984, respectively. All tillage systems started to emerge at 40 to 55 GDD and reached a maximum emergence at 70 to 80 GDD. During the first 5 weeks after emergence, corn growth parameters (plant height, leaf area, dry matter) of NT were consistently lower, and in some cases significantly lower than CN. These growth parameters were highly correlated with GDD. The RGR fluctuated in the same manner as the daily 5‐cm soil temperature during the first 5 weeks after emergence. The correlation coefficients of log RGR vs. daily mean soil temperatures were highly significant and followed the soil temperature trends. Thus, the lower soil temperature associated with CT systems, especially NT, is one of the main factors affecting emergence and seedling growth and development.