bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Slope on Size and Distribution of Fields in Iowa
Authors: Runge E. C. A. , Riecken F. F. 
Published: July 2010

AbstractThe objective of this investigation was to determine the percentage of the land in Iowa and in the major soil associations within Iowa that would fall into various field sizes when slope criteria were the only factors determining field size. A method was developed to determine the percentage of land which would fall into various field sizes (10–160 acres or ca. 4–65 hectares). Slope and acreage of individual soil mapping delineations for selected fields within each 1/4‐section (ca. 65 hectares) tract was the input in this study. The soil map data by 1/4‐sections represents a 2% sample of Iowa and consists of approximately 4,500 individual 160‐acre tracts. For this study, 100 1/4‐section tracts were selected in each of the four replicates. The number of 1/4‐sections included in each replicate for each soil association was the same as the percentage of that soil association in Iowa.The frequency of occurrence of different size fields meeting six sets of slope criteria are given with 5 and 10% confidence intervals for Iowa, and without confidence intervals for soil associations within Iowa. As field size increased and as more level fields were evaluated, the percentage of land in Iowa meeting the slope criteria decreased. Most of the large nearly‐level fields are in soil associations in northwest and north‐central Iowa, and in the Missouri and Mississippi river bottomlands. The within 1/4‐section variance was less than that between 1/4‐sections.
A Simplified Method for Preparation of Soil Thin Sections
Authors: Gile Leland H. 
Published: July 2010

AbstractA simplified method for thin section preparation requires a relatively small amount of materials and time. Heating is required only twice, no evacuation is necessary, and only one impregnating solution is used. A ratio of 3.5 parts of acetone to 1 part of Laminac resin is used for impregnation, with Lupersol DDM as a catalyst. Impregnated chips and cover glasses are attached to slides with clamps, using epoxy as a cementing agent. The method has satisfactorily impregnated both noncalcareous and highly calcareous soil materials ranging in texture from clay to loamy sand, with and without gravel.
Relationships Among Electrochemical Properties, Type of Colloid and Adsorbed Cations of Soil and Mineral Colloidal Suspensions
Authors: Rhoads F. M. , Nash V. E. 
Published: July 2010

AbstractPotentiometric cation activities, electrophoretic mobilities and specific conductance at variable frequencies were determined on suspensions of five reference clay minerals and five soil clays. The objectives of this work are: (i) to determine the relationship between clay mineralogy and specific conductance with a variable frequency power source, (ii) to determine the interrelationship among the various electrochemical measurements, and (iii) to study the effect of different exchangeable cations on the electrochemical properties.Montmorillonitic minerals with a charge deficiency in the octahedral layer showed the greatest change in specific conductance with increasing frequency. Vermiculite, on the other hand, showed less evidence of a change in conductance with frequency; illite showed no change. This was taken to indicate that a greater proportion of the exchangeable cations on montmorillonite was in the Stern layer whereas the cations on the higher surface charge density clays were distributed between the Gouy and the chemisorbed layer.A Stern layer on the montmorillonite minerals developed to a greater extent for monovalent cations than divalent. The divalent cations were apparently located between the unit layers of the mineral and did not conduct electric current even at high frequencies.
The Significance of Apatite Inclusions in Soil Phosphorus Studies
Authors: Syers J. K. , Williams J. D. H. , Campbell A. S. , Walker T. W. 
Published: July 2010

AbstractApatite inclusions have been identified in several primary minerals, and their abundance and morphology have been described. A comparison of several methods used for the determination of total P in soils showed that Na2CO3 fusion is the most reliable method for samples which contain apatite inclusions and that the effectiveness of extraction was usually in the order: Na2CO3 fusion > HF digestion > HClO4 digestion > N H2SO4 extraction following ignition. Included apatite was identified using a petrological microscope in residues after digestion with 60% HClO4. This form was also extracted much more slowly by 0.5N HCl than was nonincluded apatite. Included apatite resistant to attack by 1N HCl was determined as “residual inorganic P” in fractionation studies on weakly weathered materials, and the influence of fineness of grinding on the ratio of “acid‐extractable Ca‐P” to residual inorganic P indicated the likely dimensions of the inclusions in different minerals.
Influence of Cations on Flocculation of Clay Minerals by Microbial Metabolites as Determined by the Electrical Sensing Zone Particle Analyzer
Authors: Santoro T. , Stotzky G. 
Published: July 2010

AbstractFlocculation of clay minerals by microbial metabolites was determined by measuring changes in particle‐size distribution. No floculation occurred when clay and metabolite mixtures were analyzed in sodium metaphosphate as the suspending electrolyte. When the mixtures were analyzed in electrolytes containing the chloride salt of the cation to which montmorillonite was made homoionic, all metabolites caused flocculation in the presence of trivalent cations, some with divalent cations, but none with monovalent cations. Similar results were obtained with purified rhizobial polysaccharides, which, however, also flocculated kaolinite homoionic to Na. The degree of flocculation of the clays differed with the source of the metabolites. A nonionic polyacrylamide (Separan) flocculated both montmorillonite and kaolinite, regardless of the type of cation present. The possible implications of these results in the aggregation of soil by microorganisms are discussed.
Synthesis and Transformation of Phenolic Compounds by Epicoccum nigrum in Relation to Humic Acid Formation
Authors: Haider K. , Martin J. P. 
Published: July 2010

AbstractDuring the growth of the fungus Epicocium nigrum in glucose‐asparagine medium, 2,4‐dihydroxy‐6‐methylbenzoic acid(orsellinic acid) and 2‐methyl‐3,5‐dihydroxybenzoic acid (cresorsellinic acid) are synthesized. These are altered by decarboxylation, by introduction of additional hydroxyl groups, by oxidation of methyl groups, and by further decarboxylation to form over 20 phenols. Some of the phenols are trihydroxy benzene compounds such as 2,4,5‐trihydroxy toluene, which are autoxidizable at pH values of 6 or above. These compounds, after autoxidation to quinones, couple with resorcinol‐type phenols or with o‐diphenols. Nonresorcinol type phenols added to the culture solution are altered by introduction of hydroxyl groups, by demethoxylation, and by oxidative splitting of the side chain. The benzene ring is essentially resistant to degradation by the fungus. Amino acid compounds present in the culture medium or formed by the organism are either linked into oxidative polymers of the phenols or are deaminated by action of some of the oxidized phenols. “Humic acid” formation commences at about pH 6 in the nutrient solution and is associated with the disappearance of the phenols. Carbon‐14 studies indicated that the phenol ring of added compounds takes part in polymer formation. With time, mixtures of the same phenols synthesized by the fungus and peptides or amino acids will react to give “humic acid”‐type compounds, However, evidence for weak phenoloxidase activity in the fungus mycelium was found. During autolysis this phenolase may be released into the medium and could further an oxidative polymerization of the phenols and their autoxidation products.
Relative Absorption of Strontium and Calcium by Certain Algae
Authors: Fuller Wallace H. , Hardcastle James E. 
Published: July 2010

AbstractThe relative uptake of strontium and calcium was compared, using seven different species of algae (A. falcolus var. aci cularis, Scenedesmus, sp., Pediastrum sp., Sphaerocystis sp., Phormidium sp., Nostoc sd., and Anabaena sp.,) isolated from fresh water and arid land. Uptake always fovored calcium over strontium when the two elements were present in nutrient media together. Strontium was absorbed in addition to the calcium requirement. With Scenedemus sp., however, strontium actually appeared to compete with calcium.
An Acid‐Free Vanadate‐Molybdate Reagent for the Determination of Total Phosphorus in Soils
Authors: Tandon H. L. S. , Cescas M. P. , Tyner E. H. 
Published: July 2010

AbstractAn acid‐free vanadate‐molybdate reagent was developed for the spectrophotometric determination of P in HClO4 digests of soils. The optimum acidity in the analysis is derived from the residual acidity of the HClO4 digest of soils. A comparative study of the proposed reagent with a commonly used molybdenum‐blue method on ten widely different soils indicated that the proposed method gave highly reproducible results and was not affected by high amounts of Fe3+ which is invariably present in soils. In rare cases chromium interference can be serious because of the similarity of the color of the chromate ion to that of the molybdivanadophosphoric complex. For soils low in chromium, chromate interference can be removed by volatilization as chromyl chloride during the digestion. The modified reagent greatly simplifies the determination of total P and is admirably suited for automated analysis.
Interaction of Limestone Particle Size and Phosphorus on the Control of Soil Acidity
Authors: Barrows Harold L. , Taylor Alan W. , Simpson Elmer C. 
Published: July 2010

AbstractVarious size fractions of limestone and calcite were equilibrated in a Leon fine sand previously treated with varying rates of phosphorus. The efficiency of 42‐ to 48‐mesh liming material was reduced 1.1, 1.6, and 5.8%, respectively, by the addition of 25, 50, and 150 ppm P. The same levels of P reduced the efficiency of 12‐ to 14‐mesh material 2.2, 3.6, and 8.5%. Material finer than 80‐mesh was not affected. The reduced efficiencies were attributed to the formation of surface coatings of phosphatic material. The susceptibility of a given soil to coat liming material may be assessed by measurements of hydrogen ion (H+) and phosphate (H2PO4‐) potentials.
Potassium Fixation by Amorphous Aluminosilica Gels
Authors: van Reeuwijk L. P. , de Villiers J. M. 
Published: July 2010

AbstractSynthetic aluminosilica gels fixed potassium in varying amounts against replacement by common alkali and alkaline earth cations; the larger the solvated size of the replacing cation the greater was the amount of K retained. Replacing power thus followed the lyotropic series NH4 > Na > Ba > Ca > Mg. The amounts of K fixed against exchange by a particular ion increased with total cation‐exchange capacity (in turn dependent on gel composition) and with the pH value at which K‐saturation originally took place. A marked increase in capacity to fix K was shown to result from drying the gels prior to K‐saturation. Drying presumably increased the rigidity of channels in the gel structure which restrict the passage of larger hydrated cations and which, as with zeolites, are responsible for the fixation phenomenon. For xerogels, wet‐ and dry‐fixation measurements yielded results of the same order of magnitude.
Microbially Induced Phytotoxicity in Stubble‐Mulched Soil
Authors: Norstadt Fred A. , McCalla T. M. 
Published: July 2010

AbstractIncubations of subtilled soil amended with wheat straw (Triticum aestivum L.) caused the development of a phytotoxic soil. Studies of the toxic soil and wheat residues revealed increased Penicillium urticae Bainier numbers and formation of patulin, a potent phytotoxic substance. Microbial activity, as measured by plate counts and O2 consumption, increased as phytotoxicity increased. Inoculation of incubated, amended, non‐sterile subtilled soil with P. urticae B. caused the greatest proliferation of the fungus and patulin formation at the time intervals corresponding to highest phytotoxicity. The plant symptoms and the inhibition of Trichoderma sp. during incubations of the subtilled soil were indications of patulin formation. Associated microorganisms during incubation of subtilled soil amended with wheat straw quite likely caused the development of a substrate favorable to P. urticae B. growth and patulin formation.
Genesis and Relative Weathering Intensity Studies in Three Semiarid Soils
Authors: Smith B. R. , Buol S. W. 
Published: July 2010

AbstractThe role of clay illuviation and clay formation in situ in the development of argillic horizons in arid and semiarid regions has been the subject of some controversy among pedologists. This study included two profiles with argillic horizons and one profile without an argillic horizon.Thin section examinations revealed very few illuviation cutans and some stress cutans. Fine clay (< 0.2µ) / coarse clay (2‐0.2µ) ratios increased in the argillic horizon of the two Haplargid profiles. Relative weathering intensities within the three profiles were estimated from CaO/ZrO2 molecular ratios obtained by X‐ray spectrographic analysis of the silt fraction. These molecular ratios indicate that maximum weathering has occurred at or near the soil surface and that weathering has decreased with depth in all of the profiles studied. It is concluded that clay formation in situ is not solely responsible for the development of an argillic horizon in arid and semiarid soils. More likely, both clay formation in situ and enrichment by illuviation of fine clay (<0.2µ) are responsible for the argillic horizons in soils of arid and semiarid regions.
Self‐Diffusion of Tritiated Water in Montmorillonite and Kaolinite Clay
Authors: Phillips R. E. , Brown D. A. 
Published: July 2010

AbstractThe quick‐freeze technique of measuring diffusion coefficients of ions in clays and soils was adapted to the measurement of self‐diffusion coefficients of tritiated water in clays. The self‐diffusion coefficients of tritiated water were approximately equal in the kaolinite and montmorillonite clays. The water contents, oven‐dry weight basis, used for montmorillonite were 125.0, 118.5, 100.0, and 87.0%; the water contents used for kaolinite were 60.5, 55.0, 43.5, and 39.0%. The calculated average number of water layers on each mineral surface ranged from 3.5 to 5.5 for montmorillonite and from 17 to 26 for kaolinite. The self‐diffusion coefficients in creased in a linear manner as the average number of water layers present on each mineral surface increased; a slightly different rate of increase was obtained for each of the two clays. The lack of difference of the diffusion coefficients in the two clays could not be explained on the basis of charge density of the clays nor was a difference in viscosity a plausible explanation. A longer path length of the diffusing water molecules in the kaolinite and a smaller relative mobility of the diffusing water molecules in the montmorillonite is given as a possible explanation.
Retention of Boron by Layer Silicates, Sesquoxides, and Soil Materials: II. Sesquioxides
Authors: Sims J. R. , Bingham F. T. 
Published: July 2010

AbstractBoron retention by hydroxy iron and aluminum materials was found to be pH dependent with maximum retention occurring in the alkaline range. The hydroxy aluminum materials retained B in amounts that were an order of magnitude greater than the amounts retained by the hydroxy iron materials. Boron retention by these materials was significantly reduced by aging on a steam bath prior to being treated with B.Iron and aluminum were precipitated from solutions in the presence of B in application of the “mole ratio” method of determining the formulas of complexes. Evidence was obtained indicating Fe(III) or Al(III) and B were precipitated in stoichiometric proportions. Considering these precipitated forms as “solid complexes” with the general formula, MXn, a greater variety of complexes was found in the Al(III) systems than in the Fe(III) systems. In the Fe(III)‐B systems, values of n for the most part were ≤1.0; in the Al(III)‐B systems, values of n were ≥1.0.Samples of similar constitution to those used in the “mole ratio” study were prepared for each metal at three pH levels. The amount of B combined in the precipitate was determined as a function of aging. The amount of B combined in the precipitate of the pH 6 samples remained relatively unchanged throughout the course of the 42‐day aging period whereas the amount of B combined in the pH 9, 10, and 11 samples decreased with time. Since the observed decreases in the amounts of B combined in the precipitates were limited to the pH 9, 10, and 11 samples, it was concluded that the ready source of hydroxyl ion in these suspensions promoted hydrolysis of the hydroxy iron and aluminum precipitates, resulting in expulsion of B from the precipitates probably as borate ions.
Influence of pH, Calcium, Iron, and Aluminum on the Uptake of Radiophosphorus by Cranberry Plants
Authors: Medappa K. C. , Dana M. N. 
Published: July 2010

AbstractRadiophosphorus accumulation by the cranberry (Vaccinium macrocarpon L.) was studied in relation to pH, Ca, Fe, and Al in nutrient solutions. There was no direct effect of H+ activity on radiophosphorus (32P) accumulation by the plants between pH 3 and 7. However, with the medium at pH 8, phosphorus (P) accumulation was depressed. From media at pH 3 to 7, the plants were capable of accumulating comparable amounts even at low levels of 32P activity. Calcium concentrations from 0 to 750 ppm and Fe concentrations from 0 to 50 ppm had no appreciable effect on the uptake of 32P. Phosphorus accumulation tended to increase with the addition of 1.2 ppm Al but decreased with 12 ppm or more. This decrease in P accumulation in the presence of Al was more pronounced at pH 6.5 than at pH 3.5 or 4.5. It is suggested that at the highest pH value aluminum phosphate precipitated both inside and outside the root tissue and thereby impaired P accumulation in the shoots.
Tolerance of Soybean Varieties To High Levels of Phosphorus Fertilizer
Authors: Dunphy E. J. , Meissen M. E. , Fulcher C. E. , Kurtz L. T. 
Published: July 2010

AbstractA soybean (Glycine Max. L. Merr.) variety classified as “tolerant” to very high levels of P fertility was paired and compared with a “very sensitive” variety in field experiments involving seven levels of P fertilizer (0, 16, 49, 147, 442, 1,330, and 3,980 kg P/ha). These experiments were carried out at two locations with three pairs of varieties over a 3‐year period, and irrigation was included as a variable at one location for 2 years.Yields of “tolerant” and “very sensitive” varieties were similar at the lower P levels, although responses by the “very sensitive” variety sometimes appeared slightly larger.Yields of all varieties were depressed by the largest P application, but the yield of the “tolerant” member of each pair was always greater than that of the “very sensitive” variety. At this largest P addition, the average yield of the “very sensitive” varieties was only two‐thirds of that of the “tolerant” varieties. These results were consistent with the “tolerance classification” that had been made previously by Howell and Bernard (4) from the behavior of the varieties in solution culture under greenhouse conditions.Irrigation resulted in marked increases in yields of both “tolerant” and “very sensitive” varieties, but no interactions were found among irrigation, varieties, and levels of P fertilizer.The observed relation between P‐fertilizer additions and yield of soybeans indicated that the addition of the P‐fertilizer in geometric rather than arithmetic increments would often be advantageous for such experiments involving a wide range of fertilizer additions.
Organic Soils on the Lower Coastal Plain of North Carolina
Authors: Dolman J. D. , Buol S. W. 
Published: July 2010

AbstractThe organic deposits on the lower Coastal Plain of North Carolina form a blanket of variable thickness over a mineral landscape which was dissected during the Wisconsin glacial period. The characteristics of the soils developed in the organic deposits show a distinct relationship to their position over the pre‐peat landscape.The soils found over the higher parts of the pre‐peat landscape are chiefly classified as Leptists and mineral soils with histic epipedons. They consist of debris from a mixed swamp forest vegetation, have brown to black colors, are well aerated, friable, and show considerable faunal activity.The soils found over the lower parts of the pre‐peat land scape are chiefly classified as Saprists. They are formed from remains of Nyssa‐Taxodium swamp vegetation, have reddishbrown to dark reddish‐brown colors, are poorly aerated and are structureless. When wet they are paste‐like but upon drying they become hard, often irreversibly so. They are more acid than the shallow organic soils, and very little faunal activity is in evidence.Translocation of organic matter can be observed in the shallow organic soil but presently not in the deep area. The organic matter in the deep soil appears to be more resistant to oxidation than that in the shallow organic soil.
Availability of Boron in Various Boronated Fertilizers
Authors: Mortvedt J. J. 
Published: July 2010

AbstractRates of B dissolution from various boronated fertilizer granules in soil increased with the level of water‐soluble B in the fertilizers. Effectiveness of B for alfalfa (Medicago sativa L.) was similar whether partially dehydrated borax (Na2B4O7 · 5H2O) was either mixed alone with the soil or incorporated with various fertilizers and applied to the soil in a greenhouse experiment. Uptake of B increased with rate of applied B, but forage yields were not affected. Plant uptake of B correlated well with a combination of the level of water‐soluble B in the fertilizers and the number of granules applied, but not with either parameter alone. This suggests that dissolution of B from boronated fertilizers and distribution in the soil are important for optimum application of B with macronutrient fertilizers.Forage yields and P uptake by corn (Zea mays L.) and alfalfa were increased with rate of P applied as concentrated superphosphate (CSP) in another greenhouse test. The inclusion of various concentrations of B as borax in CSP granules did not affect yields or P uptake by either crop, indicating that borax can be incorporated into this fertilizer without impairing its effectiveness as a P source.
Clay Retention, Activities, and Excised Root Uptake of Ions in Bentonite Suspensions and Dialyzates
Authors: Snyder G. H. , Reicosky D. C. , McLean E. O. , Franklin R. E. 
Published: July 2010

AbstractSuspensions of bentonite clay saturated with varying Ca and K or Rb ratios and containing several concentrations of CaCl2 or KCl were membrane equilibrated with equal volumes of water. Activities and concentrations of Ca and K or Rb, and Cl ions in both suspension and dialyzate phases were determined with electrode and radioactive tracer techniques. The “suspension effect” (greater activity of cations and lesser activity of anions in the suspension than in the dialyzate phase) increased with increased K saturation (decreased Ca saturation) and with decreased electrolyte concentrations. Permanent charge cation exchange sites appeared to contribute most to the suspension effect, while the pH‐dependent charges favored hydrolysis of the metallic cations and thus tended to mask the suspension effect.A given concentration of electrolyte was many times more effective in causing changes in cation retention by the clay phase when the clay was predominantly saturated with Ca rather than with Rb. Higher retention of cations at high Rb saturations generally paralleled the electrode‐measured activities and excised root uptake (corn and soybeans) of cations. Addition of 0.2 S of CaCl2 decreased the differences in cationic activities between phases and generally eliminated significant differences in uptake between phases.