bluuebunny/crossref_metadata_2025_split huggingface dataset:
Topsoil and Subsoil Thickness Requirements for Reclamation of Nonsodic Mined‐land
Authors: Halvorson G. A. , Melsted S. W. , Schroeder S. A. , Smith C. M. , Pole M. W. 
Published: July 2010

AbstractEight trenches were excavated to a depth of 4.6 m and filled with one of three different textures of spoil to evaluate topsoil and subsoil thickness requirements for crop production on nonsaline, nonsodic spoil material. Yields of wheat (Triticum aestivum L.) in 1979 and 1982, barley (Hordeum vulgare L.) in 1980, and corn (Zea mays L.) in 1981 and 1983 were compared on plots with 0.23, 0.46, or 0.69 m of topsoil replaced over loamy sand spoil with and without subsoil, over clay loam spoil, or over silty clay loam spoil. Crop yields increased with increasing thickness of replaced topsoil, especially on trenches filled with loamy sand spoil. Crop yields were greater when subsoil was replaced than when no subsoil was replaced on loamy sand spoil at a given topsoil thickness. Average yields from the trenches were equal to or better than average yields from undisturbed plots in 1979 and 1983. On irrigated plots in 1983, response of silage and corn grain to subsoil/spoil treatments was similar to the nonirrigated plots. Wheat grown on irrigated plots in 1982 did not respond significantly to topsoil thickness or subsoil/spoil treatments. At least 0.69 m of topsoil plus subsoil was required to achieve highest yields on nonsodic, nonsaline, loamy sand spoil, but 0.46 to 0.69 m of topsoil was sufficient for highest yields on clay loam and silty clay loam nonsaline, nonsodic spoil. Crop yields were not increased by broadcast applications of N and P fertilizer.
Effects of Subsoiling and Mechanical Impedance on Tobacco Root Growth
Authors: Vepraskas M. J. , Miner G. S. 
Published: July 2010

AbstractRelationships between mechanical impedance and root growth have not been extensively defined for field conditions, and as a result, it is usually impossible to know with certainty when soil layers of high mechanical impedance are limiting root growth or where subsoiling is needed to improve root development. The primary objective of this investigation was to describe relationships between mechanical impedance and root concentration for both subsoiled and nonsubsoiled tillage treatments in field studies. Experiments were conducted at three locations in the North Carolina Coastal Plain on soils that were coarse‐textured Typic and Arenic Paleudults with tillage pans. At each site, flue‐cured tobacco (Nicotiana tabacum L.) was grown in subsoiled and nonsubsoiled (moldboard plow/disk) tillage treatments replicated four times. Penetrometer readings were made in the row and 0.30 m to the side of the row at 6‐ to 14‐d intervals for periods of 28 to 42 d; these data were averaged by depth and position and were expressed as mean cone index (CI). At approximately 52 and 75 days following transplanting, roots were counted by the trench‐profile method. At all locations, numbers of roots below the Ap horizon were significantly greater for the subsoiled, as compared to nonsubsoiled treatments for both root count dates. Mean CI was significantly correlated with root concentration in the Ap and E‐B horizons at all locations with r values ranging from −0.79** to −0.88** for both root count dates. The three tillage pans examined had mean CI's between 2.8 to 3.2 MPa. Subsoiling reduced the CI of the tillage pans for up to 47 d from transplanting and permitted significantly greater root penetration of the subsoil.
Extent and Persistence of Subsoil Compaction Caused by Heavy Axle Loads
Authors: Voorhees W. B. , Nelson W. W. , Randall G. W. 
Published: July 2010

AbstractWheel traffic of heavy farm machinery is causing increased concerns about soil compaction. To offset the increasing weight of large equipment, tires have increased in both size and numbers in an effort to keep constant the contact pressure on the soil surface. Recent research has indicated, however, that increasing axle load can cause increasing and deeper compaction irrespective of surface contact pressure. Axle loads of 9 and 18 Mg were applied in replicated field experiments initiated in 1981 and 1982 in Minnesota as part of an international cooperative study on the effects of high axle loads on deep soil compaction and plant response. Such axle loads are typical of modern harvest and transport equipment. These heavy axle loads were applied only at the beginning of the experiment, and are compared with check treatments where axle loads are limited to ≤4.5 Mg. Various soil parameters were measured to assess the extent and persistence of subsoil compaction. When the subsoil was relatively dry, axle loads of 9 and 18 Mg did not cause significant changes in bulk density, penetrometer resistance, or hydraulic conductivity deeper than about 20 to 30 cm, the normal depth of tillage. However, when the subsoil was relatively wet, bulk density increased about 0.08 Mg m−3 from about the 30‐ to 50‐cm depth. Saturated hydraulic conductivity decreased from 2 to 0.2 cm h−1 due to 18‐Mg axle load on a Webster clay loam (Typic Haplaquolls). A similar relative decrease was measured on a Nicollet clay loam (Aquic Hapludolls). Evidence of subsoil compaction persistence was measured 4 yr after initial heavy axle loading in spite of annual winter soil freezing to depths up to 90 cm.
Changes in Void Distribution and Volume During Compaction of a Forest Soil
Authors: Lenhard Robert J. 
Published: July 2010

AbstractBulk density and water retention measurements were conducted after 0, 1, 2, 4, 8, 16, and 32 trips with a rubber‐tired skidder on a forest soil whose surface was formed from volcanic ash. Changes in these measurements were used to evaluate effects of travelling intensity with heavy equipment on some soil physical properties. Bulk density reached a maximum after four trips and remained statistically constant with additional trips. A parameter indexing the poresize distribution, however, changed after four trips. The distribution of flow channels, therefore, was altered even with no significant change in mass per unit volume relationships. Compression of the soil during each skidder pass and elastic rebound thereafter was identified as the mechanism resulting in changes of the pore‐size distribution while bulk density remained constant. Effects of heavy equipment operation on the pore‐size distribution and water retention properties should be recognized in forest management.
Evaporite Mineralogy Associated with Saline Seeps in Southwestern North Dakota
Authors: Timpson M. E. , Richardson J. L. , Keller L. P. , McCarthy G. J. 
Published: July 2010

AbstractSaline seepage in western North Dakota occurs when water in excess of crop use leaches soluble salts from the root zone and transports them laterally to lower landscape positions. Evapotranspiration moves these dissolved salts upward through the soil, resulting in salt crust formation at the surface. This study was undertaken to detail the mineralogic changes occurring as saline waters migrate through the soil profile, and to determine the mineralogic composition of the saline efflorescences present at the soil surface of four saline seeps in Hettinger County, North Dakota. Mineralogic changes resulting from upward water movement in soils were accurately predicted using the Hardie‐Eugster model of closed basin brine evolution. The sequence calcite‐gypsum‐ and mixed Na‐Mg‐(SO4) minerals occurs as saline waters migrate upward through the profile. The following minerals occur in surface efflorescences; mirabilite, thenardite, epsomite, hexahydrite, bloedite (Na2Mg(SO4)2·4H20), konyaite (Na2Mg(SO4)2·5H20), loewite Na12Mg7(SO4)13·15H2O), and gypsum. Hydration state, mineral occurrence, and mineral solubility were seasonally dependent.
Air Encapsulation: I. Measurement in a Field Soil
Authors: Fayer M. J. , Hillel D. 
Published: July 2010

AbstractEncapsulated air is an important component of shallow water table fluctuations. Our objective was to measure the quantity and persistence of encapsulated air in a field setting. Using sprinkling rates of either 3.5 × 10−6 or 3.8 × 10−5 m s−1, we brought the water table in a field soil from a depth of 1.5 m to the surface on several occasions. Moisture contents during and after sprinkling were monitored with a neutron probe. Twice following sprinkling, the water table was maintained at the surface for more than 20 d, during which time we continued to monitor moisture contents. With the water table at the surface, differences between the porosity and the measured moisture content were attributed to encapsulated air. Encapsulated air contents ranged from 1.1 to 6.3% of the bulk soil volume, depending on the rate of sprinkling, soil depth, and initial soil moisture content. During ponding, encapsulated air persisted at the 0.3m depth for up to 28 d. The results indicate that encapsulated air is measurable in a field situation and that its quantity and persistence should be considered in analyzing the results of similar field experiments.
Nitrification Rates in Profiles of Differently Managed Soil Types
Authors: Hadas Aviva , Feigenbaum Sala , Feigin A. , Portnoy Rita 
Published: July 2010

AbstractThe variation of nitrification rates among soils and within soil profiles has received little attention compared with the well‐established relations with soil moisture and temperature. In this study, the rate of nitrification was determined in profiles of various soil types and under different agricultural management. Verhulst's equation was used to express the accumulation of nitrate (NO‐3) with time and modified to describe the rate of ammonium (NH+4) decrease. The maximal rate of nitrification (Kmx) and the delay period (t′) were derived from the equation and used to characterize quantitatively the nitrification process in various soil samples. The Kmx and t′ of surface soil samples were from 5 to 70 mg kg−1 d−1 and from 0.2 to 8 d, respectively. The Kmx decreased and t′ increased with soil depth. Soil factors mostly affecting the rate parameters were: pH decreasing from 7.8 to 6.6 or HCO‐3 decreasing below 1 mol m−3, previous agricultural management, and soil depth. Data obtained from 15N studies indicated that mineralization rate of soil organic N in NH+4‐treated soils was not always negligible relative to nitrification.
Desiccation Tolerance of Clover Rhizobia in Sterile Soils
Authors: Fuhrmann J. , Davey C. B. , Wollum A. G. 
Published: July 2010

AbstractProcedures were developed to examine the effect of low soil moisture on clover rhizobia (Rhizobium leguminosarum biovar trifolii, formerly R. trifolii). A study was then conducted to determine the feasibility of identifying desiccation‐tolerant rhizobia as a possible means of improving inoculant quality for cool‐season, annual clovers (Trifolium L.). Five clover rhizobia isolates were tested for response to three water potential regimes in two sterile soils over a 42‐d incubation period. Initial soil water potential for all treatment combinations was −0.1 MPa. The three water potential regimes imposed were a constant −0.1‐MPa treatment and two progressive desiccation treatments having equilibrium potentials of ca. −70 and −500 MPa, respectively. These treatments were obtained by using sulfuric acid solutions to manipulate the relative humidity levels of the atmosphere surrounding the inoculated soils. The two soils used (0–10 cm) were an Altavista (Aquic Hapludults) loamy sand and a Cecil (Typic Hapludults) sandy clay loam. Overall survival of the rhizobia was highest, and relative persistence of the isolates was similar, in both soils at the −0.1 MPa treatment. Population levels were generally lowest under the −70 MPa desiccation regime. Population trends under the desiccation regimes were strongly affected by soil type and appeared to reflect the differential desiccation rates observed between the physically dissimilar soils. Although soil type also affected relative survival among the rhizobia, one isolate exhibited excellent survival at all treatment combinations. The more consistent estimates of relative desiccation tolerance were obtained with the finer‐textured Cecil soil, −500 MPa desiccation regime, and a minimum 21‐d incubation period.
Pedogenic Imogolite and Soil Environments: Case Study of Spodosols in Quebec, Canada
Authors: Wang C. , McKeague J. A. , Kodama H. 
Published: July 2010

AbstractSpodosols similar in parent material, relief, and age but different in soil climate and vegetation were studied along two transects in Quebec, Canada. Soils of the northern transect (between 50 and 52°N) were under spruce (Picea mariana) forest in a colder region than that of the southern transect (at 46°N) where the forest was mainly deciduous, dominantly maples (Acer sp. L.) with greater rooting depth. Major differences in properties of pedons between the two transects were: total organic C in B horizons of the northern pedons was less than half that in southern pedons, and ratios of inorganic to organic amorphous Al and Fe in B horizons of the northern pedons were 5 to 10 times that of the B horizons of the southern transect. Both the lower organic C content and the higher ratios of inorganic to organic amorphous Al and Fe in the pedons of the northern transect may be attributed to the differences in vegetative cover, soil temperature, and biological activities of the two transects. Pedogenic imogolite was detected in all B and some C horizons of the northern transect but in none of the pedons of the southern transect. The high organic C content in the pedons of the southern transect is thought to retard the formation of imogolite. The domination of inorganic forms of amorphous Al and Fe in the spodic and spodic‐like horizons of the northern transect support the hypothesis that much Al and probably some Fe are translocated and deposited as inorganic complexes with Si in some Spodosols. It indicates the desirability of basing the chemical criteria of a spodic horizon on an extractant that removes both organic and inorganic amorphous products of pedogenesis. The currently‐used pyrophosphate extractant removes mainly organic‐associated forms of Al and Fe.
Transformations of Biotite to Kaolinite During Saprolite‐Soil Weathering
Authors: Rebertus R. A. , Weed S. B. , Buol S. W. 
Published: July 2010

AbstractBiotite transformations in 10 pedons representing a developmental sequence of soils formed from coarse‐grained regional metamorphic rocks in the Piedmont and lower elevations of the Blue Ridge provinces of North Carolina are reported. Kaolinite is common to abundant in sand fractions of six of the pedons and is found to some extent in nine of the 10 pedons. Most of the kaolinite is derived from the pseudomorphic (isomorphic and largely isovolumetric) alteration of biotite. Biotite first alters to interstratified biotite‐vermiculite in which the vermiculite is hydroxy‐Al interlayered. The kaolinization of biotite extends throughout the grain, the pseudomorphs retaining the morphology of the biotite precursor but having the optical and structural properties of kaolinite. The koalinite pseudomorphs can be considered as single crystals because unit cells within the individual grains are all aligned crystallographically. A transformation model is proposed that accounts for most of the properties observed in weathering biotite. The degree of kaolinization of biotite increases with nearness to the soil surface and with increased degree of soil development. In the saprolite of the shallowest Dystrochrept biotite is relatively unweathered. In the sola of deeper Dystrochrepts and fine‐loamy Hapludults most of the biotite is kaolinized. Sand‐sized kaolinite pseudomorphs are less elastic and tenacious than fresh biotite and begin to physically disintegrate in the upper sola of fine‐loamy soils under the influence of processes of pedoturbation. In deeply developed clayey soils, kaolinite pseudomorphs may be absent from the sola. The increased clay content of clayey soils over that of fine‐loamy soils is largely a result of claysized kaolinite added from the comminution of sand‐sized kaolinite pseudomorphs of biotite.
Characterization of Hydroxy‐Aluminum Solutions by Aluminum‐27 Nuclear Magnetic Resonance Spectroscopy
Authors: Bertsch Paul M. , Thomas Grant W. , Barnhisel Richard I. 
Published: July 2010

AbstractLaboratory synthesized hydroxy‐Al solutions were characterized by nuclear magnetic resonance (NMR) spectroscopy. Solutions ranging in Al concentration from 3.4 × 10−3 to 1.0 mol L−1 at OH/Al ratios (ñ) of 0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 1.75, 2.25, and 2.50 prepared with base injection rates of 0.6 and 1.2 cm3 min−1 were investigated. For concentrated solutions (0.5 mol L−1), two polymeric species produced observable resonance peaks, the [AlO4Al12(OH)24(H2O)2]7+ polynuclear (i.e., “Al13”) species with a chemical shift (δ) 63‐ppm downfield of the hexaaquaaluminum species, and the dimer Al2(OH)2(H2O)4+8, which displayed a broad resonance ≅ 3‐ppm downfield from the hexaaqua‐Al cation. In solutions of much lower Al concentration (3.4 × 10−2 mol L−1), the Al13 polynuclear species was observed at ñ>0.25 and its concentration was found to increase linearly as a function of ñ. For ñ = 2.5, the concentration of the Al13 polymer decreased at the 1.2 cm3 min−1 base injection rate; however, this was not the case at the 0.6 cm3 min−1 neutralization rate where the concentration continued to increase linearly. The data suggest that the distribution of Al species in partially neutralized solutions are acutely sensitive to Al concentration and neutralization rate.
Determining the Saturated Hydraulic Conductivity of a Soil Containing Rock Fragments
Authors: Brakensiek D. L. , Rawls W. J. , Stephenson G. R. 
Published: July 2010

AbstractMany rangeland soils contain various amounts of rock fragments (>2 mm and <75 mm), which influence soil hydraulic and water storage properties. Most published data on these properties are only for the fine earth fraction (<2 mm). Determining properties for soils containing rock fragments requires either in situ measurements or procedures that adjust fine earth fabric properties for the coarse fraction content. The hydraulic conductivity is a major determinant of the infiltration and water movement properties of soils. Additionally, the saturated conductivity is used as a scaling parameter in modeling partially saturated flow in porous media. In this Note, literature is reviewed on calculating the saturated hydraulic conductivity for soils containing rock fragments. The two most widely used methodologies are based on knowing either the volume fraction of the rock fragments or the void ratio of the field soil and the fine earth fabric. Both of these soil properties require somewhat laborious laboratory procedures. We show that a calculation of the saturated conductivity of the bulk soil can be accomplished by using only the rock fragment fraction on a weight basis. For many soils the rock fragment fraction on a weight basis is routinely determined and published. For example, the Soil Conservation Service pedon data files list the rock fraction on a weight basis. We test our calculation of the saturated hydraulic conductivity with published data on the saturated conductivity of a stony soil. We show that our simple formulation using the rock fraction on a weight basis duplicates the observed data. Furthermore, it is as accurate as the more complicated procedure requiring void ratio information.
Preferential Flow and Hydraulic Conductivity of Forest Soils
Authors: Moore I. D. , Burch G. J. , Wallbrink P. J. 
Published: July 2010

AbstractMacroscopic analytical methods, based upon the capillary rise formula and the Hagen‐Poiseuille equation, were used to quantify the combined effects of soil‐pore size and preferential flow on the hydraulic conductivity of forest soils. A density function was derived that relates effective pore diameters of heterogeneous soil‐pore systems to measured hydraulic conductivity. Density functions derived for soils from sites with different topographic influences and disturbance effects characterized the effect of preferential flow on their hydraulic conductivity. It was shown that macroscopic methods can describe preferential flow without having to resort to microscopic examination of individual pores. If the required properties of the undisturbed parent soil (hydraulic conductivity and equivalent pore size) have been characterized, then these methods can predict the effect of disturbance on the hydraulic behavior of the soils.
Infiltration and Water Extraction from Trickle Irrigation Source: The Effective Hemisphere Model
Authors: Ben‐Asher J. , Charach Ch. , Zemel A. 
Published: July 2010

AbstractInfiltration from a point trickle source in the presence of water extraction is investigated using an approximate hemispherical model. Analytic expressions for the position of the wetting front are derived. In the short‐time limit the wetting front follows a simple t1/3 dependence. The rate of advance of the wetting front depends on a single soil parameter, closely related to the saturated water content. At larger times the effects of water extraction modify the solution to an exponential approach to a limiting radius, which is determined by the balance between the competing discharge and extraction processes. The results are consistent with available experimental data and with predictions of various existing models.
Saturation, Aeration, and Color Patterns in a Toposequence of Soils in North‐central Indiana
Authors: Evans C. V. , Franzmeier D. P. 
Published: July 2010

AbstractThe purposes of this study were to determine how geomorphology and stratigraphy influence soil water and O2 regimes, how water and O2 regimes are reflected in soil color patterns, and how soil color patterns can be used to predict soil behavior and suitability for various uses. We measured water table depths, soil‐water O2 levels, and saturated hydraulic conductivity (Ksat), and described soil color patterns in soils formed in silty loess and loam glacial till in two forested toposequences. In both sequences, Aqualfs and Aquolls are on the swells and swales, respectively, of the till plain summit, and Udalfs occupy hillslope shoulder and backslope positions along drainageways cutting back into the till plain. Compact glacial till C horizons had very low Ksat values, which forced subsurface water to flow laterally, through more permeable B horizons, to lower landscape positions. In this manner, stratigraphy and shape of the land surface controlled water movement in the landscape. Udalfs had deeper water tables, shorter saturation periods, higher soil‐water O2 levels, and higher chroma colors than Aqualfs and Aquolls. Udalfs, however, were periodically saturated above a depth of 1 m. Soils with dominant chroma of 2 or less in B horizons had water‐oxygen regimes of saturation and reduction consistent with the aquic moisture regime. Soils with no chromas ≤2 but with some three or four chroma colors had water‐oxygen regimes of saturation and oxidation. Such chromas should be recognized as indicators of soils that are occasionally saturated but not reduced. These saturated‐oxidized soils are not properly recognized in soil interpretation records and published soil surveys. They can be farmed without artificial drainage but they have definite limitations for many nonagricultural uses such as on‐site waste disposal.