bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removal of Iron Oxides and Amorphous Material From Soil Clays—Treatment Sequence Effect
Authors: Johnson Leon J. , Yeh Ching‐Hwan 
Published: July 2010

AbstractIn the great majority of soil samples, more iron, alumina, and silica were found when iron removal preceded extraction of alkali‐soluble amorphous material. Iron oxyhydroxide is postulated to be present as a protective surficial coating whose removal makes accessible more alkali soluble silica and alumina. Iron may also be part of an amorphous component whose solubility in alkali is increased after removal of the contained iron by a dithionite treatment. Prior alkali treatment reduces the susceptibility of iron oxyhydroxides to the dithionite treatment.
A Procedure for Placing Large Undisturbed Monoliths in Lysimeters
Authors: Brown K. W. , Gerard C. J. , Hipp B. W. , Ritchie J. T. 
Published: July 2010

AbstractIncreasing need for studies of leaching water and possible pollutants through soil profiles led to the development of a method for placing large undisturbed soil monoliths in metal boxes for use as drainage lysimeters. Materials and equipment used in the technique are usually available or can be leased from local contractors. Monoliths as large as 1.5 m deep and with surface areas of 3 m have been taken. The technique could be used for even larger monoliths. Thus far, lysimeters have been installed in clay, sandy clay, loam and sand soils. The upper lip of several of the lysimeters described here was buried 25 cm below the surface to allow normal tillage, bed preparation and furrow irrigation.
Influence of Moisture on Rice Straw Decomposition in Soils
Authors: Pal D. , Broadbent F. E. 
Published: July 2010

AbstractLaboratory incubation experiments were conducted for 4 months at 22 ± 0.5C with two fine‐textured soils amended with doubly tagged (13C and 15N) rice straw (Oryza sativa L.) under different moisture regimes. The moisture levels were 30, 60, and 150% of water‐holding capacity, (WHC). The extent of straw decomposition was found to be a power function of time. Differential equations were derived to give rate functions for each moisture level.Native soil organic carbon loss was depressed by added energy materials when either moisture or oxygen supply limited decomposition. At 30% WHC, priming ratios were < 1.0 initially, and increased with time of incubation but did not reach unity within 4 months incubation. At 60% WHC, the ratios were > 1.0 and decreased with time of incubation but remained above 1.0 throughout incubation. At 150% WHC, priming ratios were < 1.0 and did not vary much during the entire decomposition period. The net release of straw‐N at 60% WHC was higher than at 30% WHC. At 150% WHC, straw‐N released during decomposition was lost from the system, presumably by denitrification. Soil inorganic nitrogen changes followed trends similar to net release of straw‐N. The influence of moisture variables on soil organic nitrogen transformations was more pronounced than the influence of decomposing straw.
Microcombustion Method for the Determination of Carbon‐14‐Labeled Pesticide Residues in Soil
Authors: Beard W. E. , Guenzi W. D. 
Published: July 2010

AbstractA dry combustion procedure commonly used for total carbon analysis was modified and used to determine the concentration of 14C‐labeled pesticides in soil. Modifications included replacement of the Ascarite®3 CO2 trap with a solution of an organic base compatible with liquid scintillation solvents, and minor carrier gas flow changes. Recovery of three pesticides from four soils ranged from 83 to 99% and averaged 94%.
A Field Study of Soil Water Depletion Patterns in Presence of Growing Soybean Roots: II. Effect of Plant Growth on Soil Water Pressure and Water Loss Patterns
Authors: Arya L. M. , Blake G. R. , Farrell D. A. 
Published: July 2010

AbstractSoil‐water pressure and water‐loss patterns in the root zone of soybean (Glycine max L.) genotype P.I. 79.648 were determined from daily observations during irrigation‐drying cycles for four growth periods after planting. Tensiometric measurements of soil water pressure were made on a 10‐cm square grid from one plant row to an adjacent one spaced 80 cm apart, and between 10‐ and 70‐cm depths. Water contents were inferred from pressure‐water content relationships.During the first irrigation‐drying cycle, soil‐water pressures were marked by strong lateral and vertical gradients. As plants aged from one irrigation‐drying cycle to the next, these gradients decreased; soil‐water pressures at most depths decreased more slowly with the drying time. The proportional contribution of surface layers to the total water loss from the 10‐ to 70‐cm depth interval decreased as the plants matured while contributions from the lower layers increased. These changing patterns of soil‐water pressure and water loss are consistent with the expected shift in root activity.
Methods for Measuring Short‐Chain Fatty Acids and Ammonia from Animal Wastes
Authors: Elliott L. F. , Travis T. A. 
Published: July 2010

AbstractMethods for measuring free fatty acids and ammonia‐nitrogen are discussed. Free fatty acids can be separated easily from manure constituents by steam distillation. The free acids were subsequently analyzed by flame ionization gas chromatography, following concentration and acidification of the distillate. Linear detection limits for the flame ionization detector ranged from 15 to 300 µg of acid/ml of sample with a 1‐µliter injection. Linear detection limits were increased to 1.5 µg with a 10‐µliter injection. Percent recoveries of the fatty acids ranged from 61 to 95%. Ammonia‐N was separated from light‐chain amines using the Nessler technique. Interference by methylamine and ethylamine‐N with the NH4‐N determination was only about 6% of the equivalent NH4‐N.
Nutrient Transport in Surface Runoff as Influenced by Soil Cover and Seasonal Periods
Authors: Burwell R. E. , Timmons D. R. , Holt R. F. 
Published: July 2010

AbstractNitrogen (N), phosphorus (P), and potassium (K) losses in surface runoff water and sediment were determined for five soil cover conditions on a Barnes loam soil in west‐central Minnesota. The five soil cover conditions studied were: (1) continuous, clean‐cultivated fallow; (2) continuous corn (Zea mays L.); (3) corn in rotation; (4) oats (Avena sativa L.) in rotation; and (5) hay in rotation.Losses of water, sediment, and nutrients were determined for three seasonal periods; (P1) critical runoff period caused by melting snow and ice, (P2) critical erosion period from corn planting to 2 months later and (P3) noncritical runoff‐erosion period exclusive of periods 1 and 2.Much of the annual sediment and nutrient losses occurred during the critical erosion period (P2). Snowmelt runoff (P1) accounted for much of the annual water and soluble nutrient losses.Average annual quantities of NH4‐N and NO3‐N contributed by precipitation exceeded the annual losses in surface runoff, but ortho‐P losses in surface runoff were greater than the amount contributed by precipitation.
Weathering and Authigenic Halloysite in Soil Developed in Mazama Ash
Authors: Dudas M. J. , Harward M. E. 
Published: July 2010

AbstractHydrated halloysite is the dominant clay mineral formed by weathering of Mazama dacitic tephra. Allophane was also identified as a weathering product in some soils developing in this volcanic deposit. The amount of weathering and clay formation is related to soil moisture contents. In well drained upland soils, localized formation of clay occurred in pumiceous ash and lapilli near the contact with the palesols. Alteration of tephra in lower portions of these profiles was related to an area of higher moisture content above the less permeable paleosols. In poorly drained areas, considerable weathering of the Mazama tephra has occurred. This is evidenced by relatively high clay contents (15–20%) and easy physical disintegration of particles to a slippery paste. The Mazama tephra often appears relatively fresh even though deposition occurred 6,600 years ago. Limited weathering in upper horizons of well‐drained soils is attributed to inadequate moisture when temperatures are favorable for alteration processes.The authigenic halloysite in Mazama ash soils has a low degree of crystallinity suggesting early stages of formation. Low degree of order is indicated by loss of diffraction peaks after heating to 300C for 2 hours and low endothermic peak temperatures during differential thermal analysis.
Chemical Weathering of Glauconite
Authors: Abudelgawad Gilani , Page A. L. , Lund L. J. 
Published: July 2010

AbstractGlauconite samples were collected from geologic cuts in the Barce Plateau in the eastern part of Libya. The glauconite was associated with limestone, dolomitic limestone, marl, marl stone, chert, and kaolinite. Samples of the glauconite from the area of study after removal of carbonates gave X‐ray diffraction spacings of 10.0, 7.2, 5.0, 3.6 and 3.3 Å. Spacings of 10.0, 5.0, and 3.3 Å represent the 001, 002, and 003 reflection of micaceous components. Spacings of 7.2 and 3.6 Å were due to kaolinite. No 060 reflection was observed for random samples. The absence of this spacing, although not entirely specific for glauconite, is indicative of glauconite‐like minerals. Petrographic analysis and chemical composition confirmed that the micaceous mineral studied was glauconite. (The term glauconite in the area of the study was given by the field geologist based upon the morphology of the micaceous material.)Potassium depletion of the glauconite by sodium tetraphenyl boron (NaTPB) treatment produced diffraction spacings of 14 to 15 Å when Mg saturated. Amounts of K removed by NaTPB and by exhaustive treatments with 1N NaCl were 183 and 179 meq/100 grams, respectively, which were about 95% of the total potassium as determined by Na2CO3 fusion. This demonstrated that essentially all of the K in the glauconite is of interlayer origin.Equilibrium studies showed that the rate of K removed from the glauconite by 1N NaCl was dependent upon contact time and suspension density. Selectivity coefficients for the exchange of K by Na at equilibrium were about 2500. Infrared spectra of K‐depleted glauconites were quite similar to the IR spectrum of the specimen layer silicate nontronite. Amounts of K removed by and cation exchange capacities following selective K depletion techniques, the chemical composition, X‐ray diffraction and the infrared spectra show that K‐depletion of glauconite gives rise to an iron rich vermiculite.
Simple Flow Plugs for Regulating Gas Composition
Authors: Miller D. E. 
Published: July 2010

AbstractOxygen and nitrogen contents in a gas were accurately controlled by passing compressed air and nitrogen at regulated pressure through flow plugs. The flow plugs were constructed from bronze oxygen hose couplers with porous plastic dises as flow restrictors. Gas flow rate through a plug was varied by changing the number and porosity of disks and the applied gas pressure.
Decomposition of Carbon‐14 Labeled Plant Materials in a Grassland Soil Under Field Conditions
Authors: Nyhan J. W. 
Published: July 2010

AbstractA study was made of decomposition of plant materials under field conditions using carbon‐14 labeled blue grama (Bouteloua gracilis [H.B.K.] Lag. x Steud.). A grassland soil was amended with blue grama herbage and roots in February 1971 and sampled at intervals until March 1972. For ground blue‐grama herbage buried in the top 2.6 cm of soil at two amendment levels (128 and 1,280 kg/ha) 54–57% of initially added carbon‐14 was lost in 412 days. For plant‐root material at amendment levels of 384 and 1,920 kg/ha, only 26–37% of the carbon was lost in this time period. Rates of carbon loss were significantly affected by season of burial; plants buried in February and May exhibited losses of 56% in 335 days and 42% in 314 days, respectively. Segments of blue‐grama herbage mixed with soil and placed on the soil surface for 412 days showed carbon losses of 39 and 50%, respectively. Additions of fresh, blue‐grama herbage to soil containing partially degraded, labeled plant material had no significant effect on radiocarbon loss rates.The experimental technique used to estimate blue grama carbon losses under field conditions is evaluated and the decomposition results are discussed relative to decay patterns of native blue grama.
Climate, Time, and Organisms in Relation to Podzol Development in Michigan Sands; II. Relationships Between Chemical Element Concentrations in Mature Tree Foliage and Upper Humic Horizons
Authors: Messenger A. S. 
Published: July 2010

AbstractComparison of the chemical composition of northern hardwood and conifer foliage within polypedons of several sandy Podzols (Spodic Udipsamments and Typic Haplorthods) in northern Michigan indicates a succession to hardwoods resulting in a significant increase in concentrations of foliar N and most other macronutrient elements accompanied by a decrease in foliar Al concentrations. These successional changes appear independent of the degree of soil acidity developed under conifers.Upper humic horizons under forest stands dominated by white pine (Pinus strobus L.) and/or hemlock [Tsuga canadensis (L.) Carr.] contain high levels of extractable aluminum and large capacities for production of crenic acid. The foliar composition of these species suggests a mechanism for considerable flux of aluminum in soil profiles and depletion of basic cations in eluvial horizons.Foliar compositions of northern hardwoods favor humus types and microflora that produce much reduced or negligible quantities of crenic acid.
Maryland Soils Developed in Residuum from Chloritic Metabasalt Having High Amounts of Vermiculite in Sand and Silt Fractions
Authors: Coffman C. B. , Fanning D. S. 
Published: July 2010

AbstractFrom 60 to 90% of the calcium exchange capacity (pH 7 Ca acetate saturation, Mg acetate replacement) was attributable to > 2µm particles in subsoil horizons of an Ultic Hapludalf developed in residuum from chloritic metabasalt in Maryland's Middletown Valley. Vermiculite was the dominant reactive mineral in several soils examined from the area. For material above the rock from which organic matter and free iron oxides had been removed, the fraction of CaEC attributable to “vermiculite” (measured by CEC methods) interlayers increased with increasing particle size and (for whole soils) with increasing depth. The vermiculite appears to have formed from chlorite at the rock‐saprolite boundary, since vermiculite is absent in the rocks and chlorite is absent in the saprolite and micas are rare in both rocks and saprolites. Weathering also produces kaolinite and free iron oxides and eventually destroys vermiculite as shown by examination of soils of differing degrees of development.Most of the pedons examined in the present and in related studies were included in the Myersville and Fauquier soil series by concepts used for a soil survey of the study area published in 1960. Both soil series are placed in Ultic Hapludulfs in the current Soil Taxonomy, but many pedons mapped as Fauquier and Myersville in the 1960 survey appear to be Dystric Eutrochrepts and some on steep slopes are Udorthents. The soils examined do not meet requirements for vermiculitic family mineralogy in present Soil Taxonomy, even though cation exchange properties appeared governed by vermiculite. Substitute criteria are proposed to base vermiculitic family mineralogy on the “vermiculite” content of whole‐soils.
The Activity Concept of Phosphate‐Rock Solubility
Authors: Chien S. H. , Black C. A. 
Published: July 2010

AbstractVariously treated samples of a finely ground Florida phosphate rock were equilibrated with dilute HCl solutions, and the ion‐activity product of the carbonate apatite mineral in the phosphate rock was then determined from analyses made on the solutions. Constant ion‐activity products or solubility‐product constants were found within a certain pH range in each instance. The solubility, as reflected by the numerical value of the constant, decreased with an increase in the proportion of the phosphate rock dissolved in the solubility determination or prior thereto. After a certain portion of the phosphate rock had been dissolved, however, no further decrease in solubility was found with further extraction of the phosphate rock. These results are similar to those obtained previously with synthetic hydroxyapatite and were interpreted in the same way, namely, that the solids are not uniform but exist in a range of activities.
Analytical Characteristics of Humic and Fulvic Acids Extracted from Tropical Volcanic Soils
Authors: Griffith S. M. , Schnitzer M. 
Published: July 2010

AbstractCertain tropical soils formed on materials of volcanic origin on islands in the West Indies, tend to accumulate substantial amounts of organic matter but are so infertile that the addition of lime and fertilizers does not increase crop response. To obtain a better understanding of this unusual behavior, humic and fulvic acids were extracted from problem soils on the island of Dominica, and characterized by chemical and spectroscopic methods.Elementary and functional group analyses as well as optical and IR data for humic and fulvic acids extracted from the tropical soils were similar to those of humic and fulvic acids from soils from widely differing climatic zones. The only major difference was the tenacity with which the tropical fulvic acids retained (in water‐soluble form) relatively large amounts of ash (between 9.4 and 12.6% of oven‐dry weights), rich in silica. Our data suggest that the unusually high resistance to degradation of organic matter in these soils is, at least in part, related to the formation of stable silica‐fulvic acid “complexes.”
Variations in the Natural Abundance of 15N of Wheat Plants in Relation to Fertilizer Nitrogen Applications
Authors: Shearer Georgia , Legg J. O. 
Published: July 2010

AbstractMeasurements were made by two laboratories of the δ15N (per mill 15N excess) of winter wheat plants (Triticum aestivum L.) grown at five locations in Pennsylvania on experimental plots. The plots were fertilized with N at various rates. The results from both laboratories showed a consistent decline in δ15N with increasing rates of N application. Such a decrease in δ15N is consistent with increasing contributions of fertilizer N to the plants as the rate of application increased, given that fertilizer N has a lower 15N content than the soil N. The coefficients of regression of δ15N of wheat on N application rate were always negative and usually significantly different from zero. The regression coefficients computed from the results of the two laboratories were not significantly different from each other in 12 of 16 experiments. There was, however, a systematic, unexplained difference in the results from the two laboratories. A regression of one set of data on the other resulted in a regression coefficient significantly different from one, the theoretically expected value.
Thermal Conductivity of a Red Pine Forest Floor
Authors: Pennypacker S. P. , Sopper W. E. , Kardos L. T. 
Published: July 2010

AbstractThe insulating value of red pine (Pinus resinosa Ait.) forest floor litter was determined by measuring thermal conductivity, k, using a heat line source method. Test specimens consisted of natural forest floor and individual samples of reconstituted needle and humus components that had respective average dry weight bulk densities of 0.058, 0.229, and 0.233 g/cm3. Measurements were taken of the organic material under both frozen and unfrozen conditions at moisture contents ranging from oven‐dry to approximately 300% by weight. The conductivity of the three materials was expressed as a function of moisture content and density at temperatures of approximately — 16 and 25C. Freezing increased conductivities in reconstructed samples of organic particles, but not in natural samples. The failure to obtain increased conductivities in natural samples is probably due to the absence of an ice formation or a structure of adjoining ice crystals within the porous humus layer.
Changes in the Physical Properties of Soil Clays Due to Precipitated Aluminum and Iron Hydroxides: I. Swelling and Aggregate Stability After Drying
Authors: El‐Swaify S. A. , Emerson W. W. 
Published: July 2010

AbstractCompressed discs of an illite, a kaolinite, and a mixture of the two were formed from freeze‐dried dispersed suspensions of the clays, into which one level of Fe(OH)3 and two levels of Al(OH)3 had been precipitated. The precipitated Fe was found to consist of particles about 40Å in diameter and amorphous to X‐ray, rather than the acicular goethite that precipitates under similar conditions in the absence of clay. It was deduced from N2 and water vapor sorption measurements that the precipitated Al was present as very thin layers on the surface of the clay particles, which in the case of the illite could bridge some of the particles. Their form was generally indeterminate, in contrast to the well‐crystallized bayerite formed in the absence of clay.All three hydroxy treatments inhibited the double‐layer swelling of the Na‐illite and Na‐kaolinite/illite mixture in dilute NaCl solutions. Both on weight percent and on an equimolar basis, Al was more effective than Fe in reducing the slaking of dry clay discs and in increasing the resistance of clay to dispersion in pyrophosphate solutions. Possible bonding mechanisms between the precipitate and the clays are discussed.
Reaction Products of Polyphosphates and Orthophosphates with Soils and Influence on Uptake of Phosphorus by Plants
Authors: Subbarao Y. V. , Ellis Roscoe 
Published: July 2010

AbstractAmmonium polyphosphate and diammonium phosphate were compared as sources of P for corn (Zea mays L.) in a growth chamber experiment with an alkaline‐calcareous soil and a slightly‐acid soil. Reaction products of the two P sources in soils and soil extracts correlated with results obtained in the growth chamber.Applied P increased dry weights, uptake of P by the plants, and available soil P in the slightly acid soil. Both sources of P effectively supplied P for plant growth on this soil. Ammonium and magnesium orthophosphates, formed as reaction products in the laboratory experiments when the two P fertilizer materials were added, should furnish sufficient P for plant growth.Neither source of P increased dry weights, uptake of P by plants, or available soil P in the alkaline‐calcareous soil as much as with the slightly‐acid soil. Dry weights of plants and uptake of P were significantly less with polyphosphate than with orthophosphate, both at 36 ppm applied P. Polyphosphate also failed to increase the available soil P. A reaction product, Ca(NH4)2P2O7·H2O, that is highly stable in alkaline‐calcareous soil was formed when ammonium polyphosphate was added. Its stability and low solubility explain the limited availability of P. The compounds, Mg2KH(PO4)2·15H2O and Ca4H(PO4)3·2.5 H2O, formed when diammonium phosphate was added. They provided more P for plants at the highest rate of application, but uptake of P was limited for both sources of P in this soil.