bluuebunny/crossref_metadata_2025_split huggingface dataset:
Miscible Displacement: IV. Mixing in Glass Beads
Authors: Nielsen D. R. , Biggar J. W. 
Published: July 2010

AbstractA column of 390µ glass beads was used in a series of miscible displacement experiments to investigate over a wide range of flow velocities the contributions of diffusion and variations in pore‐water velocities to mixing. The two fluids were aqueous solutions of Na2SO4 and NaCl having equal densities and with tritium added to the NaCl. A desired minimum solute‐solid interaction was obtained as indicated by the data. It was found that diffusion causes a significant amount of mixing during displacement. An application of the information to the movement of nutrients in the soil moisture stream is discussed.
Effects of Past Agricultural Practices on the Survival and Growth of Planted Trees
Authors: Gilmore A. R. , Boggess W. R. 
Published: July 2010

AbstractFour pine species (loblolly, shortleaf, red, and white) and three hardwood species (sycamore, green ash, and yellow‐poplar) were planted on a recently abandoned agronomic experimental field in southern Illinois that had been used for 40 years to test crop rotations with various soil and fertilizer practices. After 7 growing seasons, pine survival and growth were poorest on the old limed plots (attributed to competition from weeds). After 6 growing seasons, hardwood survival and growth were best on the old limed plots. The effect of the tree species and the past fertilizer practices upon the chemical composition of the soil are given. Five years after plots were planted to pines, soil organic matter remained approximately the same on fertilized plots but nearly doubled on unfertilized plots.
Potassium and Ammonium Taranakites, Amorphous Aluminum Phosphate, and Variscite as Sources of Phosphate for Plants
Authors: Taylor A. W. , Lindsay W. L. , Huffman E. O. , Gurney E. L. 
Published: July 2010

AbstractAs shown by the response of three successive crops of corn, the effectiveness of potassium and ammonium taranakites as sources of phosphorus increased with prolonged contact with the soil. This effect was independent of the soil pH. Potassium taranakite was a consistently better source of phosphorus than ammonium taranakite.On acid soil, amorphous aluminum phosphate was a moderately effective source of phosphorus, whereas crystalline variscite was ineffective. On calcareous soil, amorphous aluminum phosphate, variscite, and both taranakites were as effective as monocalcium phosphate, and on this soil the particle size of the aluminum phosphate was the controlling factor in their effectiveness.
Saprophytic Activity of Rhizoctonia as Affected by the Carbon‐Nitrogen Balance of Certain Organic Soil Amendments
Authors: Davey C. B. , Papavizas G. C. 
Published: July 2010

AbstractCarbon (C) from cellulose added to soil slightly suppressed the competitive saprophytic activity of Rhizoctonia, whereas nitrogen (N) from NH4NO3 increased it. Cellulose and NH4NO3, combined to produce a wide range of C/N ratios and incorporated in soil, suppressed Rhizoctonia activity at most C/N ratios. With certain exceptions, soil bacteria and fungi increased in numbers with decreasing C/N ratios. Soil streptomycetes were not greatly affected. Oat straw and soybean hay enriched with NH4NO3suppressed Rhizoctonia activity at all C/N ratios tested. The cellulolytic fungus Humicola greatly increased in numbers in the presence of decomposing oat straw whereas Trichoderma was not affected.
Complexing of Metals by Soil Organic Matter
Authors: Mortensen J. L. 
Published: July 2010

AbstractSoil organic matter forms complexes with metals by ionexchange, surface adsorption, chelation, and complex coagulation and peptization reactions. Little is known concerning the nature of the ligands in polymeric components of soil organic matter which chelate metals, but carboxyl, hydroxy, and amide groups are probably involved. A number of low molecular weight compounds capable of chelating metals have been isolated from soils.Metallo‐organic matter complexes must be identified and characterized before unequivocal evidence for their formation in soils can be obtained.
Recovery of Fixed Ammonium by Corn in Greenhouse Studies
Authors: Walsh L. M. , Murdock J. T. 
Published: July 2010

AbstractThe availability of native fixed NH4 and applied NH4 fixed in the Ap and B1 horizons of a Dodge silt loam was investigated. In addition, the effect of freezing on the fixation of applied NH4 was studied. By applying K and N to either the same or separate layers of soil in green‐house pots it was also possible to evaluate the effect of K on the release of fixed NH4. When NH4 and K were applied in the same layer of soil, the Ap and Bl horizons fixed 5 and 15% of the added NH4, respectively. An additional 5% of the added NH4 was fixed in each horizon when the soil was frozen after applying NH4. However, when NH4 and K were applied to separate layers of soil, negligible amounts of NH4 were fixed. Highly significant correlations between exchangeable K in the moist soil after cropping and the amount of applied NH4 fixed as measured by differential N uptake showed that the level of exchangeable K in the soil controlled the release of fixed NH4 to the crop. Correlations between two methods of measuring fixation of applied NH4, namely, differential N uptake and analysis of the soil after cropping, were highly significant.These studies also indicated that about 15% (0.12 me. per 100 g.) of the native fixed NH4 in the Bl horizon was released when the level of exchangeable K in the soil was very low. However, very little native fixed NH4 was released from the Ap horizon, presumably because sufficient K remained in the soil of this horizon to block release of fixed NH4. These studies indicate that even under the most advantageous conditions very little of the native fixed NH4 is available to crops.
Some Geographic Aspects of the Seventh Approximation
Authors: Orvedal Arnold C. , Austin Morris E. 
Published: July 2010

AbstractThe Seventh Approximation sharpens the relationship between soil classification and soil geography; and it is likely to lead to more valid geographic correlations between genetic factors and soil morphology. Although the Seventh Approximation is expected to bring about only a few changes on large‐scale, detailed soil maps, the opposite is true for small‐scale, general soil maps. Even on the general maps, however, many, perhaps most, soil boundaries will appear where they would have appeared using the current soil classification; but the changes will be drastic in the nomenclature. The fact that substantive names are, or will be, provided for all classes in all categories makes soil classes of all categories available for use on maps. This fact makes possible a better matching of categorical and cartographic levels of generalization. The Seventh Approximation does not alter the need for the concepts of soil phases and soil associations.
Influence of Variations in the Diffusivity‐Water Content Relation on Infiltration
Authors: Hanks R. J. , Bowers S. A. 
Published: July 2010

AbstractEstimates of the influence of variations in the diffusivity (or conductivity)‐water content relation on infiltration were made using a numerical method. Where the diffusivity was increased or decreased up to a factor of two at saturation, infiltration was markedly changed. However, variations of the diffusivity by a factor of 100 at drier moisture contents had no significant influence on infiltration. This implies that infiltration is governed, to a large extent, by the soil properties at water contents near saturation and is little influenced by soil properties at drier water contents.
Factors Responsible for Poor Response of Corn and Grain Sorghum to Phosphorus Fertilization: III. Effects of Soil Compaction, Moisture Level and Other Properties on P‐Zn Relations
Authors: Ward R. C. , Langin E. J. , Olson R. A. , Stukenholtz D. D. 
Published: July 2010

AbstractGreenhouse experiments were used to study soil compaction, moisture level, soluble P and Zn, pH, organic matter and clay contents, K saturation and titratable alkalinity as these soil factors influenced P‐Zn relationships in corn. Some of the resulting observations help to explain why starter fertilizers containing P may on occasions cause depressions in plant growth.Fertilizer P applied in the row markedly reduced Zn concentration of corn. Increasing soil compaction and soil moisture level caused further depressions of Zn concentration. The combination of irrigation practice on newly graded (and compacted) land, especially when soil P is high, would seem to portend Zn deficiency problems.Soil K saturation also appears to have a decided influence on P‐Zn relations in the plant. The higher the percent K saturation of the soil, the less did applied P reduce plant utilization of Zn in these experiments.
Morphology and Genesis of a Sol Brun Acide with Fragipan in Uniform Silty Material
Authors: Jha P. P. , Cline M. G. 
Published: July 2010

AbstractThe physical, chemical, and mineralogical data assembled indicate that physical phenomena have been major factors involved in the development of genetic horizons of a Sol Brun Acide with a fragipan. Gross mineralogy is primarily inherited; chemical alteration is confined mainly to fine fractions in zones of maximum permeability above the fragipan and along connecting fracture planes. Evidence is presented that compaction by glacial ice, periglacial phenomena, or weight of overburden is not essential for development of density in fragipans. Density and firmness are attributed to reorganization of particles upon alternate dessication and wetting, possibly augmented by seasonal frost action and some illuviation of clay. Dessication is suggested as the major factor in development of polygonal fracture planes. Clay destruction by weathering is suggested as a major factor contributing to the character of zones of apparent eluviation. It is suggested that the fragipan is being degraded both from the top and from the fracture planes.
Miscible Displacement: V. Exchange Processes
Authors: Biggar J. W. , Nielsen D. R. 
Published: July 2010

AbstractMiscible displacement experiments have shown that the physical processes associated with microscopic flow velocities should be included in any theory of exchange during flow through soils. Water contents and average‐flow velocities were controlled in Oakely soil columns initially saturated with Ca ion. Without disturbing the water content and flow velocity, Ca acetate of 0.1N and 0.05N concentration was displaced by MgCl2 solutions of similar concentration. The distribution of Mg2+ and Cl‐ ion in the effluent was related to the volume passing through. Mg2+ ion appeared in the effluent well in advance of that predicted on the basis of exchange theory. Three mathematical models that include the exchange process were compared with the data to ascertain their usefulness in predicting positions and shapes of breakthrough curves. Although the theories were generally inadequate, they did serve to emphasize the important contribution of microscopic flow velocity and ionic diffusion to the mixing or dispersion of solutions in porous media and to exchange processes.
The Effect of Soil Moisture Content Upon the Uptake of Molybdenum, Copper, and Cobalt by Alsike Clover
Authors: Kubota Joe , Lemon E. R. , Allaway W. H. 
Published: July 2010

AbstractThe effect of soil moisture level on the uptake of Mo, Cu, and Co by alsike clover was investigated in a greenhouse experiment with two Brown Podzolic soils from New Hampshire and a Weisenboden and a Brown soil from Nevada. A wet soil condition increased the Mo in the soil solution and plant Mo content on all four soils. The Co concentration in the soil solution was higher in pots maintained at the high moisture level than at the low moisture level. This increase in Co concentration with soil wetness was reflected in alsike clover, over four cuttings, on the two Brown Podzolic soils, but not in plants from the two Nevada soils. Copper contents in the plants and in the soil solution did not differ consistently because of soil wetness.
A Field Measurement of Total Porosity and Surface Microrelief of Soils
Authors: Burwell R. E. , Allmaras R. R. , Amemiya M. 
Published: July 2010

AbstractTotal porosity of the layer to be plowed was estimated from undisturbed cores collected before primary tillage. Using a point quadrant instrument, soil surface elevation measurements were made before and after preplant tillage, and after each cultivation to determine the effects of tillage on total porosity of the plowed layer. Large apparent differences in capacity to detain water, as inferred from total porosity, were observed among preplant tillages and among particular combinations of preplant and postplant tillage that are used in the western Corn Belt.When total porosity of the plowed layer was measured in the ensuing fall and spring, relatively small changes in total prosity were observed. This result suggests that this physical property persists over a long time in a Barnes loam.To evaluate the effects of tillage on surface geometry and temporary water storage in surface depressions, macro and random surface roughness as measured by the point quadrant instrument are considered. Estimates of the standard error among logarithm of the elevation heights differed among tillage treatments. The standard error is suggested as an index of random roughness.
Monovalent‐Divalent Cation‐Exchange Equilibria in Soils in Relation to Organic Matter and Type of Clay
Authors: Pratt P. F. , Grover B. L. 
Published: July 2010

AbstractCation‐exchange equilibria at pH 7 were measured using ion pairs of Na‐Ca, Li‐Ca and Li‐Mg on each of 10 soils. Data on Li‐Mg and Na‐Ca ion pairs were nearly the same and data on Li‐Ca were highly correlated with exchange equilibria data on both Na‐Ca and Li‐Mg. Two soils containing largely amorphous clay minerals showed a higher preference for Li than soils containing dominantly crystalline clay minerals. Destruction of the organic matter in two soils increased the ratio of Na to Ca adsorption to a much greater extent than would be predicted by the decrease in measured surface charge density. At a sodium‐adsorption ratio (SAR) of 100 (mmole per liter)1/2, organic‐matter free soils containing dominantly montmorillonite and illite clays had ratios of Na to Ca adsorption of 1.66 to 1.94 (excluding one soil, 1.66 to 1.78). Two soils with dominantly amorphous minerals had ratios of 0.92 and 1.10, and one soil with a mixture of kaolinite, illite, and amorphous clays had a ratio of 1.35.
The Role of Hydrolysis in the Reaction of Heavy Metals with Soil‐Forming Materials
Authors: Hodgson J. F. , Tiller K. G. , Fellows Martha 
Published: July 2010

AbstractThe proposition that hydrolysis may account for the selective adsorption of heavy metals by clay surfaces is compared with an alternate explanation of specific exchange of the metal with weakly dissociable H+. It is shown that past evidence offered in support of the two hypotheses is somewhat ambiguous. Theoretical treatment is presented for the competition of ions in adsorption reactions which provides a means of distinguishing between the two alternatives through the effect of H+ on the metal‐clay reaction in the presence of a competing ion. Experimentally, the effect of H+ on the reaction of Co2+ with montmorillonite is studied in the presence and absence of Mg2+, a weakly competing ion. Ionic strength is held constant, and nonspecific reactions are minimized with an excess of CaCl2. The results are interpreted as favoring the hydrolysis hypothesis. Inherent assumptions are considered.
The Effect of Cation‐Exchange Capacity, Clay Content, and Fixation on Rubidium‐86 Diffusion in Soil and Kaolinite Systems
Authors: Evans S. D. , Barber S. A. 
Published: July 2010

AbstractAn investigation of the factors influencing the diffusion of Rb86 in eight soils showed that the more strongly Rb86 was absorbed by the soils the slower was the rate of diffusion. In leached soils that were dried after labeling, diffusion was correlated with the amount of Rb86 fixed against NH4OAc extraction. In leached soils that were kept moist after labeling, diffusion was closely related to clay content and exchange capacity. In dilute kaolinite systems, diffusion was related to the amount of Rb86 in solution.
The Effect of Rubidium‐86 Diffusion on the Uptake of Rubidium‐86 by Corn
Authors: Evans S. D. , Barber S. A. 
Published: July 2010

AbstractUptake of Rb86 by corn roots was highly correlated with the diffusion of Rb in soil and kaolinite systems. At values of Dp/b above 1 × 10‐6 cm.2 sec.‐1 the relationship was curvilinear whereas it was more nearly linear at rates less than this. The curvilinear relation at the higher rates of diffusion was attributed to the limitations of the rate of absorption of the root.
A Comparison of Mg2+, Ca2+, and Sr2+ as Exchange Ions for Mineralogical Studies of Clays
Authors: Weed S. B. , Leonard R. A. 
Published: July 2010

AbstractStrontium‐, Ca2+‐, and Mg2+‐saturated clay minerals were studied with respect to X‐ray diffraction, differential thermal analysis, cation exchange capacity, and glycerol adsorption. In general, 3‐layer clay minerals saturated with Sr2+ lost interlayer water at lower temperatures and at higher vapor pressures than did Mg2+‐clays; Ca2+‐clays were intermediate. A clay mineral‐ion‐saturation interaction was apparent. Calcium‐ and Sr2+‐saturation of clays yielded similar values for cation exchange capacity. Strontium‐saturated 3‐layer clays retained more glycerol than did clays saturated with Ca2+. Expansion of vermiculite with glycerol and ethylene glycol was dependent on cation saturation and lattice charge. Strontium‐saturated vermiculites expanded to near 16Å. more readily than did Mg2+‐clays, and Ca2+‐clays were intermediate. Vermiculites with high lattice charge expanded less readily than did vermiculites with relatively low lattice charge.Strontium can satisfactorily substitute for Ca2+ and Mg2+ in routine mineralogical studies of clays though special care may be needed to control relative humidity. Additional information regarding lattice charge of 3‐layer clays may be obtained by using several divalent ion saturations.
Comparative Properties of Plant Lignins and Humic Materials of Soils. 1. Yields and Cation Exchange Properties of Plant Lignins Isolated by Different Techniques
Authors: Thompson S. O. , Chesters G. , Engelbert L. E. 
Published: July 2010

AbstractYields and cation‐exchange capacities for Ca and Cu were determined for lignin samples isolated with 72% H2SO4, HCl‐H3PO4 mixture, 5% aqueous NaOH, and 1,4‐dioxane. Yields varied with extractant in the order: acid‐ > dioxane‐ > NaOH‐extracted lignins. For equal time, a higher yield of dioxane pine lignin was obtained by fractional than by a one‐step extraction. In most cases cation‐exchange capacities varied with lignin source and with method of extraction as follows: (a) Straw lignins > wood lignins; (b) alkali‐ > dioxane‐ > acid‐extracted lignins.Lignins isolated by fractional extraction with dioxane showed the later fractions to have higher exchange capacities. Values for the one‐step extracted isolates were intermediate with respect to the high and low values of the fractionally isolated samples. Lignin, like soil organic matter, had higher adsorptive capacity for Cu than for Ca, and the adsorptive capacity was pH dependent. All samples examined for the effect of pH on Cu adsorption showed the same relative change in adsorption for a given change in solution acidity.
Zinc Availability in Calcareous Michigan Soils as Influenced by Phosphorus Level and Temperature
Authors: Ellis Roscoe , Davis J. F. , Thurlow D. L. 
Published: July 2010

AbstractYield of corn was increased from 7,504 to 8,680 pounds per acre by an application of 4 pounds of Zn per acre to a calcareous Wisner clay loam in a field experiment. In a greenhouse experiment with the same soil, yield, Zn concentration in the plant tissue, and total Zn uptake by corn were decreased when soil temperature was decreased from 75 to 55°F. Ten pounds of Zn per acre increased the Zn concentration in the corn tops. In a greenhouse experiment with a Kawkawlin‐Wisner loam, 10 pounds of Zn per acre increased the yield of field beans when the treatments included high levels of either applied or residual P. In greenhouse experiments, applications of 437 and 655 pounds of P per acre decreased the Zn concentration in field beans and corn. In most experiments, a negative correlation was noted between Zn and P concentrations in the plant tissue.
Mobility of Water Adjacent to Mineral Surfaces
Authors: Kemper W. D. , Maasland D. E. L. , Porter L. K. 
Published: July 2010

AbstractMobility of water adjacent to Na‐ and Ca‐saturated bentonite surfaces was estimated from diffusion rates of deuterium hydroxide in oriented clay pastes at several moisture contents. The first molecular layer of adsorbed water on Na‐ and Ca‐clays had mobilities which were 30 and 5%, respectively, of the mobility of water molecules in bulk water. There was an indication of a slight reduction in mobility of water as far as 40Å. From the sodium‐saturated clay. However, water more than three molecular layers from the solid surface had mobilities which were 60% of the mobility in bulk water. The mobility data indicate that water outside the first adsorbed molecular layer does not have viscosities more than 2.5 times the viscosity of bulk water.
Importance of Volumetric Expression of Water Contents of Organic Soils
Authors: Boelter D. H. , Blake G. R. 
Published: July 2010

AbstractMethods for evaluating water contents and bulk densities of several different peats are compared. Because bulk densities (saturated volume basis) of moss, herbaceous, and aggregated peats varied from 0.028 to 0.249 g. per cc., a highly distorted impression of the amount of water actually held under field conditions is given if water values are expressed on an oven‐dry weight basis.On a wet‐volume basis, moss peat held only 10 to 20% more water at saturation than did herbaceous and aggregated peat and retained less water than they did at higher suctions. Between 0.1 and 15 bars, moss peat retained about one‐quarter the volume of water of a medium‐textured mineral soil, Barnes loam.Since considerable volume reduction occurs on drying, bulk density of oven‐dry peat, Db (dry volume basis), represents an artificial condition rarely, if ever, occurring in undrained bogs. Bulk densities must, therefore, be calculated on the basis of the wet bulk volume and are referred to as Db (wet bulk volume). A more precise expression of degree of wetness may be substituted for “wet” in the wet volume basis term.
Some Variables Affecting the Measurement of “Catalase Activity” in Soil
Authors: Johnson John L. , Temple Kenneth L. 
Published: July 2010

AbstractHydrogen peroxide decomposition rates were measured on five soils after incubation with and without added organic matter and bentonite. The measurement was affected by soil type, addition of organic matter, addition of bentonite and drying of the sample. The two‐factor interactions of soil × organic additive, soil × added bentonite, soil × drying, organic additive × bentonite and bentonite × drying were highly significant. The three‐factor interaction of soil × organic additive × bentonite was significant. The reaction rate was greatly increased by incubation with powdered milk but only partly lowered by autoclaving.