bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spatial Distribution of Soil Heat Flux and Growing Degree Days
Authors: Wolf J. K. , Rogowski A. S. 
Published: July 2010

AbstractIn agricultural areas, groundwater pollution by NO2‐3 from excessive fertilizer, manure, and amendment applications is becoming a serious problem. To control such pollution, assessment of the potentially most critical recharge zones is needed. Spatial parameterization of soil heat flux can delineate areas of high C and N mineralization and help identify such zones. Soil heat‐flux distributions were estimated on a central Pennsylvania farm and surrounding watershed from changes in the optical‐rotation angle of a sucrose solution, water content, and bulk density. The change in rotation angle is a function of soil temperature and occurs during the chemical reaction when sucrose is converted to glucose and fructose. Volumetric soil water content and bulk density were used to compute soil heat capacity. Estimates of soil temperature and heat capacity were combined to produce estimates of soil heat flux and growing degree days at different scales. Their spatial distributions were computed using geostatistical techniques. Measured and derived properties were found to exhibit anisotropic spatial structure related to soil‐forming factors and scale. Land‐use management implications suggest that this method identifies warmer or colder zones as well as areas with high or low C and N mineralization potential on farm and watershed scales.
Interactions of Microorganisms and Soil during Fenamiphos Degradation
Authors: Ou L.‐T. 
Published: July 2010

AbstractEnhanced degradation of a number of pesticides occurs in soils with a history of previous exposure to the chemical. Little is known, however, about the duration of enhanced degradation after a single field application of a pesticide or the microorganisms responsible for the enhancement. Soil samples collected 2, 3, and 4 yr after one application of the nematicide fenamiphos [ethyl‐3‐methyl‐4‐(methylthio)phenyl (1‐methylethyl) phosphoramidate] at a rate of 4.48 kg ha−1 to an experimental site planted in potato (Solanum tuberosum L.) near Hastings, FL, were used to determine mineralization rates and total‐toxic‐residue (TTR) disappearance rates. Both mineralization rates and TTR disappearance rates in samples collected 2 and 3 yr after field application were enhanced compared with the corresponding control samples. Half‐lives for TTR in soil samples collected 2 and 3 yr after field application of fenamiphos were 22 and 89 d, respectively, while half‐life values for the corresponding control samples were 131 and 130 d. During a 70‐d incubation period, 67.2, 27.8, and 9.8% of applied 14C‐fenamiphos was mineralized in soil samples collected 2, 3, and 4 yr after field application, while 10.8, 11.5, and 9.5% of applied 14C‐fenamiphos in the corresponding control samples was mineralized. Mineralization rates in soil collected 4 yr after field application were the same as in the control sample. Microorganisms capable of degrading fenamiphos could not be isolated from the soils. A mixed bacterial culture derived from soil collected 2 yr after the field application, in the presence of a small amount of this soil, however, did mineralize fenamiphos. Without the small amount of soil, the mixed culture did not mineralize the nematicide.
Determination of the Aromaticity of Humic Substances by X‐Ray Diffraction Analysis
Authors: Schnitzer M. , Kodama H. , Ripmeester J. A. 
Published: July 2010

AbstractAromaticity is an important indicator of the origin, stability, and chemical reactivity of soil humic materials. The only method available at the present time for measuring the aromaticity of these materials is 13C nuclear magnetic resonance (NMR), so that there exists a need for an alternate, independent method. With this in mind, we developed a method based on the x‐ray diffraction (XRD) analysis of humic materials. Total areas in XRD patterns are subdivided into areas due to G (aromatic) and γ (aliphatic) bands. The G‐band area, expressed as a percent of the total area, is assumed to be a measure of the aromaticity. The method was tested on 14 natural humic acids, one natural fulvic acid, and one synthetic humic acid. Aromaticities so measured were then compared with aromaticities computed from 13C‐NMR spectra. The agreement between the two methods was acceptable. This establishes the XRD method as a valid alternative to the 13C‐NMR method.
Equations for Estimating the Amount of Nitrogen Mineralized from Crop Residues
Authors: Vigil M. F. , Kissel D. E. 
Published: July 2010

AbstractThe amount of N mineralized or immobilized during the decomposition of a crop residue will influence the amount of N available for crop uptake and will ultimately impact N‐management practices and groundwater quality. The objective of this work was to determine quantitative relationship(s) between a crop residue's chemical properties and the potential net amount of N that would mineralize in a season. Eight experiments (six from the literature and two conducted by the authors) were combined to determine general relationships between net N mineralized and residue chemical characteristics. Regression analysis indicated that 75 and 72% of the variability in the measured amounts of N mineralized in the eight experiments could be explained using either the C/N ratio or the square‐root transformation of N concentration of the residue, respectively. The break point between net N mineralization and net immobilization was calculated to be at a C/N ratio of 40, which corresponds to a N concentration of about 10 g N/kg (assuming residue C is 400 g/kg). Eighty percent of the variability in the amount of N mineralized could be explained by a regression equation that included N and the lignin‐to‐N ratio as independent variables. The fitted equations provide estimates of the maximum amount of N that potentially will mineralize in a season from incorporated crop residues of different N contents.
Soil Genesis Associated with Periglacial Ground Wedges, Laramie Basin, Wyoming
Authors: Munn L. C. , Spackman L. K. 
Published: July 2010

AbstractPeriglacial ground wedges, indicative of former dry permafrost environments during the Pleistocene, occur in the high basins of Wyoming. At a study site in the Laramie Basin in southcentral Wyoming, a comparison was made between a soil developed in a ground wedge and the soil that was host to the wedge. The wedge soil has accumulated clay (315 kg m−2), carbonate (171 kg m−2), and gypsum (155 kg m−2). Both the soils developed in the wedges and the soils in the wedge host are Borollic Natrargids, but the wedge soils are more coarsely textured and have lesser accumulation of carbonate than the host soil. Mineralogy of wedge and host soils is similar, including quartz, calcite, plagioclase, smectite, and illite. Gypsum accumulation is superimposed over carbonate‐ and clay‐accumulation horizons in both soils. The wedges are thought to have been active in pre‐Wisconsin time. Soil genesis in these soils indicates progressive accumulation of clay and carbonate. Gypsum accumulation has apparently accelerated during the Holocene in these soils.
Organic Polymers' Effect on Soil Shear Strength and Detachment by Single Raindrops
Authors: Barry P. V. , Turco R. F. , Stott D. E. , Bradford J. M. 
Published: July 2010

AbstractOrganic matter is known to influence soil erodibility, but little work has been done to determine the effects of specific organics on erosional processes. Our study was designed to assess the influence of organic polymers known to increase aggregate stability on nearsurface soil shear strength and soil detachment by single raindrops during time. An index of shear strength was obtained with a Swedish fall‐cone device and detachment was based on soil loss in the splash of a single raindrop. Two soils with similar texture but differing organic‐matter contents were used. Amendments studied were polyvinyl alcohol (PVA), an experimental starch graft polymer (SGP), and a mixture of a microbial polysaccharide rich in levans and other cellular material (LEV). The amendments initially induced significant increases in soil shear strength ranging from 1.5 to 5.5 times greater than untreated soil. The pattern of change of shear strength during time was nearly identical for all treatments, and was attributed to an aging process. Significant changes induced by the amendments in the amount of soil detached varied with time. The patterns of change during time seen in the PVA‐amended soils were similar to the controls, while the LEV and SGP response curves differed. In conjunction with decomposition‐rate data, it was concluded that the transformation products formed during the decomposition of the LEV and SGP were causing temporal changes in the soil that the Swedish fall‐cone device was insensitive to, but influenced the response of the soil to raindrop detachment.
Time Domain Reflectometry Measurements of Water Content and Electrical Conductivity of Layered Soil Columns
Authors: Nadler A. , Dasberg S. , Lapid I. 
Published: July 2010

AbstractThe major argument for measuring the soil salt concentration and water content at the same position is their high correlation and spatial variability. Time domain reflectometry (TDR) was used for simultaneous measurement of soil water content, θ (derived from the soil dielectric constant ε), and bulk soil electrical conductivity, σa (from the attenuation of a transmitted pulse), for uniform and layered soil profiles in the laboratory. The purpose of the study was to test the different concepts of travel time and attenuation by using independent estimates of θ and σa. Both parallel (two‐rod) and simulated coaxial (three‐rod) probes resulted in essentially the same ε. The three‐rod probe measurements were easier to interpret and did not necessitate an impedance‐matching transformer. The TDR measurements of θ for layered profiles were not always accurate, especially when wet soil was overlying dry soil, due to erroneous interpretation of the TDR trace. In this case, the pulse travel time should be measured at the inflection point, which is sometimes difficult to identify, and not at the minimum of the TDR trace. This study reports a new method of calculating σa, which is based on a direct measurement of the transmission‐line load by TDR. This new method, which is simpler than the previous ones and independent of multiple reflections, was found to correlate better than the previously published methods with another, independent method for σa measurement (four‐electrode technique).
Mathematical Analysis of One‐Dimensional Solute Transport in a Layered Soil Profile
Authors: Leij Feike J. , van Genuchten M. Th. , Dane J. H. 
Published: July 2010

AbstractSolute transport studies involving layered media are important for investigating how restricting layers affect rates of solute migration in the soil profile and, more generally, for examining the influence of soil heterogeneity on solute transport. Analytical solutions of the one‐dimensional advection‐dispersion equation (ADE) were obtained with the help of Laplace transforms for transport in a two‐layered soil profile. Assuming that the layers are, in effect, semi‐infinite, solutions were obtained for first‐type (constant concentration) and third‐type (constant flux) conditions at both the inlet boundary and the interface of the two layers. Concentration profiles were also obtained for a finite first layer via numerical inversion of the Laplace transform solution, using a third‐type condition at the inlet, and, simultaneously, a first‐ and third‐type condition at the interface. Volume‐averaged or resident‐type concentrations were used in all cases. First‐type conditions did not meet our criterion of mass conservation, whereas third‐type conditions caused discontinuities in the concentration at the interfaces of layers with differing transport parameters. The concentration at the interface was found to be continuous, and no mass‐balance error occurred, when first‐ and third‐type conditions were imposed simultaneously at the interface. Serveral example calculations show the effect of soil layering on solute transport in a one‐dimensional soil profile.
Weathering of a Mica by Roots and Rhizospheric Microorganisms of Pine
Authors: Leyval C. , Berthelin J. 
Published: July 2010

AbstractThe weathering of minerals within the rhizosphere has been demonstrated many times; however, only a few studies have been concerned directly with root‐microorganism interactions. This study was conducted to determine the influence of symbiotic (mycorrhizal) and nonsymbiotic microorganisms on rhizospheric weathering of mica. A lysimetric experiment was performed in a greenhouse to study the weathering of a mica (phlogopite) by roots and rhizospheric microorganisms of pine (Pinus sylvestris L.). Pine roots were inoculated or not with an acid‐producing rhizobacteria (Agrobacterium sp.) and an ectomycorrhizal fungus (Laccaria laccata [Scop.: Fr.] Berk. and Broome). In noninoculated pine, rhizospheric phlogopite particles were smaller than control phlogopite particles and partially transformed into vermiculite. Inoculation of pine roots with the bacteria increased cation‐exchange capacity and losses of K from the mica flakes. Losses were attributed to increased production of organic acids in the rhizosphere by the bacteria. Fewer losses of K were observed in pine mycorrhizosphere as monitored by x‐ray diffraction. Electron microscopic observation with a microprobe, however, demonstrated that K losses were greater for the phlogopite particles closely attached to the mycorrhizae. The mycorrhizal effect was attributed to an increase of exchange surface area, rather than to an increase in acidification. Dual inoculation significantly promoted mycorrhizal infection and phlogopite cation‐exchange capacity, compared with inoculation with the bacterium or the fungus alone.
Diagnosis and Recommendation Integrated System Modifications for Fraser Fir Christmas Trees
Authors: Rathfon R. A. , Burger J. A. 
Published: July 2010

AbstractThe Diagnosis and Recommendation Integrated System (DRIS) has been used successfully to diagnose the nutrition of many crops. Some practioners, however, cite problems in applying DRIS to certain crops. Among the problems are: identifying a suitable expression of yield, maintaining symmetry in DRIS index equations, and dealing with extremely variable micronutrients. The purpose of this study was to resolve problems as they were encountered in applying DRIS to Fraser fir (Abies fraseri [Pursh] Poir.) Christmas trees. A total of 107 Fraser fir plantations were sampled for foliage, soil, and diameter measurements. Foliage was analyzed for N, P, K, Ca, Mg, Zn, Mn, Fe, Cu, and B. Age‐adjusted diameter was used successfully as the growth‐response variable. The DRIS symmetry was maintained by including nonsignificant ratios, but setting their standardization functions equal to zero. This reduced the influence of the nondiscriminating nutrient ratios on the DRIS analysis. Norm ranges, as opposed to discrete norms, were used successfully to correct for the influence of extremely variable micronutrient ratios on the DRIS analysis. This combination of adaptations and modifications of DRIS should greatly enhance its use for this tree crop.
Comparison of Statistical and Standard Techniques to Classify and Delineate Sodic Soils
Authors: Seelig B. D. , Richardson J. L. , Knighton R. E. 
Published: July 2010

AbstractStatistical estimates of soil variability within and among delineations of taxonomic units are useful in designing and checking classification systems. We compared soil classification and spatial differentiation of a landscape dominated by sodic soils. Both statistical methodologies and standard soil‐survey techniques were used to differentiate soils. Forty‐nine pedons at three landform positions were compared with canonical discriminant analysis, principal component analysis, and kriging. Statistical analyses improved soil classification and allowed a clearer view of the field distribution of soil properties, compared with standard soil‐survey techniques. Soils with properties indicative of strong leaching (Solods) are recognized as significantly different from other soil taxonomic components at the intermediate and wetland positions. Solods were extensive at the wetland position, but could not be differentiated from Typic Natraquolls solely by morphologic observation. Although Solods are related to other leached soils, Argiaquolls and Argialbolls, they also possess soil properties that are similar to associated sodic soils. Leptic Natriborolls and Udic Natriborolls were similar except for salinity. The salinity difference by itself does not produce significant statistical differentiation between the soils of the two natric subgroüps. High salinity would be better recognized as a soil‐series phase, not a separate subgroup of Natriborolls.
Soil‐Forming Processes in Alic Melanudands under Japanese Pampas Grass and Oak
Authors: Dahlgren R. A. , Ugolini F. C. , Shoji S. , Ito T. , Sletten R. S. 
Published: July 2010

AbstractCurrent soil‐forming processes and the effect of Japanese oak (Quercus serrata Thunb.) tree invasion on soils developed under Japanese pampas grass (Miscanthus sinensis Anders.) were investigated in Alic Melanudands forming on recent dacitic tephra deposits in Japan. The Andisols examined are members of the nonallophanic group of Andisols whose clay‐sized mineralogy is dominated by Al/Fe humus complexes and hydroxy‐Al interlayered 2:1 minerals, rather than short‐range‐order aluminosilicates common to most Andisols. Two study sites were chosen that had similar soil‐forming factors except for the present vegetation. One site has remained under Japanese pampas grass, while the other site was invaded by Japanese oak 50 yr ago. To examine soil processes, soil solutions were collected for a 2‐yr period, using tension lysimeters. Results indicate that translocation of Fe, Al, and dissolved organic C is not a major process in these Andisols. Aqueous concentrations of Si are sufficient for the formation of allophane/imogolite; however, the Al appears to be preferentially incorporated into the interlayer of 2:1 layer silicates and Al‐humus complexes and is, therefore, unavailable for synthesis of short‐range‐order minerals. Invasion of the oak vegetation resulted in a lowering of soil solution pH due to production of organic acids from the decomposing oak litter, and to removal and storage of base cations in the oak biomass. The lowering of the solution pH resulted in increased Al concentrations and decreased HCO3 concentrations in the A horizons of the oak site. When compared with the pampas grass site, the oak vegetation appears to promote greater cycling of Ca, Mg, K, and Cl in the upper 20 cm of the soil profile.
Weathering Environments and Occurrence of Imogolite/Allophane in Selected Andisols and Spodosols
Authors: Ugolini F. C. , Dahlgren R. A. 
Published: July 2010

AbstractImogolite and allophane have been found in various soil environments, but most commonly occur in Spodosols and Andisols. Controversy exists regarding the origin of these short‐range‐order aluminosilicates, especially in Spodosols. The proto‐imogolite theory suggests that imogolite forms in the surficial mineral horizons and is subsequently transported to the B horizons. In contrast, evidence from analyses of soil solutions collected from Spodosols in the Washington Cascades shows that Al is migrating primarily as an organic complex, with no proto‐imogolite detected in the percolating solutions. The Andisols we studied in Japan also show an absence of imogolite/allophane in the A horizons and an abundance of imogolite in the B horizons. Extremely low levels of Al are transported from the A to the B horizons, indicating that imogolite was not translocated from the overlying A horizons. The occurrence of imogolite/allophane in the B horizons of both the Spodosol and Andisol is best explained by in situ formation. Indeed, soil solution composition from the Spodosol indicates that imogolite is unstable in the E and Bhs, but stable in the Bs, BC, and C horizons. The B horizons containing imogolite in the Spodosol and Andisol have a similar weathering environment characterized by non‐Al‐complexing inorganic proton donors (e.g., H2CO3, HNO3), low concentrations of dissolved organic C, a pH between 5 and 6.5 that promotes Al polymerization, and Si concentrations adequate to support the stability of imogolite. In situ formation of allophane and imogolite is proposed for both the Spodosol and Andisol.
Ionic Factors Affecting the Formation of Short‐Range Ordered Aluminosilicates
Authors: Huang P. M. 
Published: July 2010

AbstractThe formation of short‐range ordered aluminosilicates is substantially influenced by organic and inorganic ligands, metallic cations, and montmorillonite. Chemical composition, size, number, and nature of the functional groups, and concentrations of non‐humified organic acids play a vital role in perturbing the formation of allophanes and imogolite. Humic substances also substantially perturb the interactions of hydroxy‐Al ions with orthosilicic acid and thus inhibit the formation of these aluminosilicates. Inorganic ligands such as phosphates and sulfates vary in their ability to impede the formation of these aluminosilicates. Iron has a stronger inhibiting effect than Mn on imogolite formation, resulting in the formation of poorly ordered mineral colloids. Adsorption of hydroxy‐aluminosilicate (HAS) in the interlayers of montmorillonite results in an expanded structure. The transformation of HAS ions to noncrystalline aluminosilicates can, therefore, be affected by naturally occurring expansible layer silicates such as montmorillonite. These ionic factors perturb the genesis of allophane and imogolite to various extents, resulting in the formation of ill‐defined aluminosilicate complexes, HAS‐interlayered expansible layer silicates, and/or precipitated hydroxy‐Al‐organic or ‐inorganic complexes. Organic and inorganic ligands with a strong affinity for Al significantly modify the nature of the soluble products, which range from proto‐imogolite sol complexed with organic or inorganic ligands to hydroxy‐Al‐organic or‐inorganic complexes.
Tiron Dissolution Method Used to Remove and Characterize Inorganic Components in Soils
Authors: Kodama Hideomi , Ross G. John 
Published: July 2010

AbstractTreatments using NaOH and Na2CO3 have been widely used to remove poorly crystalline and noncrystalline aluminosilicates and hydrous oxides of Si and Al. However, NaOH treatment is often too harsh and Na2CO3 treatment is usually too mild and must be repeated. Treatment using alkaline Tiron (4,5‐dihydroxy‐1,3‐benzene‐disulfonic acid [disodium salt], C6H4Na2O8S2) was as effective as acid oxalate in the dissolution of allophane, imogolite, and poorly crystalline hydrous Fe oxides. In contrast to oxalate, Tiron effectively removed opaline silica, and the difference between extracted Si could be used to measure the amount of opaline silica. Unlike oxalate, Tiron dissolved little magnetite. As gibbsite is partially dissolved by Tiron, the rates of Al release by gibbsite (<2 µm) dissolution at different temperatures were used to estimate the gibbsite contents of soil clays containing this mineral. Generally, a single treatment with Tiron appears to be sufficient to mildly but effectively clean up samples for x‐ray diffraction of crystalline minerals with amounts of extracted Si, Al, and Fe indicating the presence and quantities of poorly crystalline and noncrystalline aluminosilicates as well as hydrous oxides of Fe, Al, and Si, including opaline silica.