bluuebunny/crossref_metadata_2025 huggingface dataset:
Auger Hole Seepage Theory
Authors: Boast C. W. , Kirkham Don
Published: July 2010

We solve the problem of water flow into a soil cavity, as an auger hole or any cylindrically shaped hole, e.g., a vertical root hole or a large circular pit, in a surrounding water‐saturated, homogeneous, porous medium. We consider the top boundary of the saturated flow medium to be a water table, with the assumption that drawdown of the water table about the auger hole during flow is small. We consider flow when (i) there is an impermeable barrier at a finite distance below the auger hole and (ii) there is an artesian source at a finite distance below the auger hole. By letting the finite distance become large in (i) and (ii) we solve the problem of a finite auger hole in a medium of infinite depth. The analysis yields, both for finite depth of soil below the auger hole and infinite depth of soil below the auger hole, a table of shape factors C. When a shape factor C is multiplied by an observed rate of rise of water in the hole, the multiplication gives the hydraulic conductivity of the soil. We compare our work, when applicable, with that of others. Our C values agree in the main with earlier C values for their limited range.
Formation of Clay‐Protein Complexes
Authors: Harter Robert D. , Stotzky G.
Published: July 2010

Proteins (catalase, α‐casein, α‐chymotrypsin, edestin, β‐lactoglobulin, lysozyme, ovalbumin, ovomucoid, and pepsin), ranging in molecular weight from approximately 17,000 to 310,000 and in isoelectric point from approximately pH 2 to 11, were adsorbed onto smectite homoionic to H, Na, Ca, Al, La, or Th. Adsorption was observed in every combination of homoionic clay and protein, even when the ambient pH of the clay suspensions (which ranged from approximately pH 3 to 7) was several units above the isoelectric point of the protein. The amount of protein adsorbed and the shapes of both the adsorption isotherms (measured by loss of protein from solution) and the binding isotherms (retention against ultimate washing with glass distilled water) were more related to the molecular weight of the proteins and to the valency of the cations on the clay exchange complex than to the ambient pH of the clay‐protein systems and the isoelectric point of the proteins. In general, the amount of adsorption was directly proportional to molecular weight of the proteins and inversely proportional to cationic valance.
Effect of Mg2+ Ion on the Solubility of Solid Carbonates
Authors: Hassett J. J. , Jurinak J. J.
Published: July 2010

The carbonate saturometer was used to determine the effect of Mg2+ ion on the solubility of four different calcareous materials. It was found that a high area calcite ≈ 13.5m2/g had a higher solubility than a low area calcite ≈ .8m2/g and that the difference in surface areas of these calcites modified the effect of Mg2+ ion on their solubilities.

Data indicated that the mineralogy of the solid carbonates can modify the effect of Mg2+ ion on the solubility of the solid phase. Carbonates which contained appreciable Mg showed a decrease in solubility with increasing Mg2+ ion, whereas carbonates with low or no Mg showed an increase in solubility.
Ionic Concentrations and Activities in Soil Solutions
Authors: Adams Fred
Published: July 2010

The chemical composition of displaced soil solutions is used to illustrate the procedure for correcting measured ionic concentrations to actual ionic concentrations and ionic activities. The procedure distributes soil‐solution electrolytes at equilibrium among their various ionic species by using equations for ion‐activity coefficients, ion‐pair dissociation, weak‐acid and weak‐base dissociation, and hydrolysis. More than a score of related equations had to be solved simultaneously; thus, mathematical solution was effected through the method of successive approximation. Rapid correction of soil‐solution analytical data to actual concentrations and activities of individual soil‐solution ions was made possible by using computer program.
Soil Solution Composition and Stability of Clay Minerals
Authors: Kittrick J. A.
Published: July 2010

Common soil minerals, such as the silicates, usually have very low solubilities and slow rates of dissolution and precipitation in the soil solution. This has tended to obscure the fact that their equilibrium reactions with the soil solution can actually be described by elementary thermodynamics. Ion analyses for soil solution‐mineral equilibria involve the same procedures and problems as do most other chemical analyses of the soil solution. The same is true for calculation of ionic strength, ion activities, equilibrium constants, and ΔG values. However, in determining mineral stabilities by the solubility method, special precautions are necessary to ensure that the activity of the desired ion species can be obtained from the measurements made and that these measurements represent true equilibrium conditions. The process involved in determining mineral stabilities is illustrated using Belle Fourche montmorillonite as the example.

The usefulness of ΔG values for common soil minerals is greatly enhanced when suitable stability equations are derived from them. These stability equations can be graphed to reveal the control of weathering relationships by the composition of the soil solution. The graphed stability equations are not merely an exercise in algebra, but are shown to represent precipitation and dissolution phenomena of real minerals. This is illustrated for the mineral group consisting of amorphous silica, montmorillonite, kaolinite, and gibbsite. The graphs help clarify field relationships that are incompletely understood and help uncover relationships previously unsuspected. The stability equations can also be used to construct equilibrium composition models for elements in the soil solution. This is a necessary first step to work on the kinetics of approach to composition limits by the soil solution.
Influence of Simulated Fall and Spring Conditions on the Soil System. I. Effect on Soil Microflora
Authors: Biederbeck V. O. , Campbell C. A.
Published: July 2010

Fall and early spring conditions were simulated by incubating unamended and N‐amended Wood Mountain loam (i) at diurnal temperatures of 14 to 3C, and (ii) by slow freezing to −23C followed by incubation at 14 to 3C. Numbers of viable soil organisms were determined by the plate‐count method after incubation at 28C. Dilution plates from the freeze‐thaw treatments were also incubated at 14, 4.5 and 14 to 3C. Plates incubated at 4.5 and 14 to 3C were reincubated at 28C.

Freezing caused a small but significant reduction in microbial numbers. Thawing at 14 to 3C was extremely lethal to the microflora. The active microflora from a recently cropped soil proved much more susceptible to this type of injury than the resting population of a stored soil. After one freeze‐thaw cycle bacteria in recently cropped soil were reduced by 92%, fungi by 55%, and actinomycetes by 33%. Addition of mineral N to stored soil reduced the detrimental effect. Simulated fall conditions caused a significant but smaller reduction of microbial numbers than simulated spring conditions. Both conditions effected qualitative changes in the soil microflora.

When soil dilution plates were incubated at 14 to 3C damage to the microflora was even more pronounced than when soil per se was exposed to simulated spring or fall conditions. It is suggested that the biocidal effect exerted by fluctuating low temperatures as occur in fall and spring can result in rates of soil nutrient cycling which are considerably lower than expected on the basis of mean temperatures.
Influence of Certain Pedogenic Factors on Potassium Reserves of Selected Canadian Prairie Soils
Authors: Somasiri S. , Lee S. Y. , Huang P. M.
Published: July 2010

The nature of K reserves of five prairie soil profiles developed from glacial till deposits and lacustrine sediments in Saskatchewan, Canada was studied.

The fraction of soil K extracted by the pretreatments prior to size fractionation was quite comparable to that of the exchangeable K. Potassium in the residue of various size fractions after sodium pyrosulphate fusion was allocated to feldspar, and the total K minus feldspar K was taken to be mica K. The fraction of K from feldspar usually increased as particle size increased. From south to north in the Prairie region under study, the fraction of K from feldspar of the soils developed from glacial till deposits increased, indicating the influence of local bedrocks on the nature of K reserves. The fraction of K from feldspar in the soil developed from lacustrine sediments was lower than that formed from glacial till deposits.

Mica genesis was evident in the Chernozemic soil, but not in the Luvisolic soil studied. In the comparable size fractions of the Gleysol and Orthic Black soils in the Oxbow catena, the lower fraction of K from feldspar in the former reflects the influence of drainage on the K reserves. Colluviation processes coupled with eluviation and illuviation have modified the nature of soil K reserves as shown by the different percent distribution of mica K and feldspar K among various size fractions.
Rapid Measurement of Chlorine in Plant Materials
Authors: Gilliam J. W.
Published: July 2010

Chlorine is extracted from ground plant material with acid and an aliquot titrated directly with an automatic chloride titrator. One technician can perform approximately 100 analyses per day with a standard deviation of approximately 0.01% Cl.
Soil Temperature Estimation by a Numerical Method
Authors: Hanks R. J. , Austin D. D. , Ondrechen W. T.
Published: July 2010

A numerical method for computing soil temperature as a function of time and depth was devised. The method allows for variable soil properties as a function of depth and requires measurement of soil temperature at or near the soil surface. Computed and measured soil temperatures agreed within 1.0C when actual soil thermal properties were used for the computation. Computed and measured soil temperatures agreed within 1.5C when soil thermal diffusivity was assumed constant at 0.20 cm2 min‐1. Actual values varied with depth from 0.21 to 0.29. Where the thermal diffusivity was assumed uniform at 0.45 cm2 min‐1, temperature errors grew from 1.0–1.7C after 3 days to 1.7–3.1C after 6 days.
Comparison of the Calorimetric and Flux Meter Measurements of Soil Heat Flow
Authors: Hanks R. J. , Jacobs H. S.
Published: July 2010

Comparisons of soil heat flow as estimated by the calorimetric, flux meter, and a combination of the two methods were made during the summer of 1969 in an oat field (Avena sativa L.). Error analysis indicated the calorimetric method had a smaller relative error than the combination method for daily soil heat flow measurements. The relative error for hourly and part‐day measurements was about the same. Daily or part‐day integrated heat flow averaged over 30 days was 24% higher for the flux meter alone than the calorimetric measurement. The combination method yielded average daily estimates that were about 65% higher than the calorimetric method. Calorimetric measurements to 16 cm and 32 cm yielded daily average values that were slightly lower than calorimetric measurements made to 64 cm. Hourly comparisons showed the correlation coefficient of the calorimetric and combination methods to be 0.97, and of the calorimetric and heat flux meter methods to be 0.93.
A Kinetic and Equilibrium Study of the Adsorption of Carbaryl and Parathion upon Soil Organic Matter Surfaces
Authors: Leenheer J. A. , Ahlrichs J. L.
Published: July 2010

Insight into the mechanisms of carbaryl (1‐Napthyl‐N‐methyl carbamate) and parathion (O, O‐Diethyl‐o‐p‐nitrophenylphosphorothioate) adsorption upon organic matter derived from the Romney silty clay loam, Zanesville silt loam, and Carlisle muck soils was obtained by twofold kinetic and equilibrium study of adsorption in nonflow aqueous systems. The differences in adsorptive characteristics of the various types of organic matter were small in both the kinetic and equilibrium studies, but changing the saturating cation from calcium to hydrogen greatly increased the adsorptive capacities for both insecticides. The magnitude of the adsorptive capacities was explained in terms of the magnitude of the hydrophobic natures of the insecticide adsorbates and the organic matter adsorbents.

Kinetic adsorption studies conducted at 5, 25, and 40C showed the rate to increase as the temperature increased with the magnitude of the initial rate constant being 10‐4 sec ‐1. The rate‐limiting step was interpreted to be diffusion of the insecticide solute molecules to the surface of the adsorbent for the first 10 min of adsorption. At longer times, intraparticle diffusion of the adsorbate into the interior of the adsorbent particles was rate limiting.
Relations Between Soil Morphology and Water‐Table Levels on a Dissected North Carolina Coastal Plain Surface
Authors: Daniels R. B. , Gamble E. E. , Nelson L. A.
Published: July 2010

Depth to water table in Typic Paleudults decreases away from the dissected edge of the geomorphic surface in east central North Carolina. This relation is linear in log log form and statistically highly significant for 19 of 22 time periods tested. The greatest changes in water‐table depths and soil morphology are within the first 0.15 to 0.3 km from the surface edge. Deep water tables are associated with thick A2 horizons and fine‐textured B horizons. The shallow water tables are associated with thin A2 horizons, low‐contrast mottling, and presence of Be bodies. This close association between water‐table depths and soil morphology is interpreted as indicating that landscape dissection, acting through its influence on water‐table depths, is one of the driving forces in genesis of North Carolina Coastal Plain soils.
Spatial Variability of Unsaturated Hydraulic Conductivity
Authors: Stockton J. G. , Warrick A. W.
Published: July 2010

Spatial variability of unsaturated hydraulic conductivity was studied for 40 ha of Pima clay loam. Calculations of hydraulic conductivity were based on the moisture release data using a modified Millington‐Quirk equation. One standard deviation to either side of the average moisture release curve resulted in a 20 to 30% variation in the unsaturated hydraulic conductivity. This offers a relatively quick and easy method for estimating variability of unsaturated hydraulic conductivity variation from pressure head vs. moisture relations. Input needed for application: moisture release relations and their variances.
The Determination of Mercury in Soils by Flameless Atomic Absorption
Authors: Melton James R. , Hoover William L. , Howard Peggy A.
Published: July 2010

A method is described for the determination of mercury in soils at the ppb level or greater. A simple digestion step, requiring no heat, is described. Determinations are made using an easily constructed apparatus for flameless atomic absorption. Soils from two states are studied for Hg content. Recoveries of mercury added to several soils ranged from 97.0 to 102.5%.
Adsorption of DDT on Solid Particles
Authors: Champion D. F. , Olsen S. R.
Published: July 2010

DDT adsorption from water by ion exchange resins, aluminum oxides, ion exchange celluloses, and soils was determined by measuring carbon‐14 labeled DDT remaining in solution. The positively charged adsorbents adsorbed more DDT from solution than the negatively charged adsorbents. In addition, the association of DDT with organic matter and colloidal clay in the aqueous phase resulting from sedimented soils increased DDT in solution.

The chlorine atoms on the ethyl group of the DDT molecule possess a slight negative charge which appeared mainly responsible for the adsorption of DDT.
Phosphorus Availability and Redistribution in Relation to Profile Development in an Illinois Landscape Segment
Authors: Smeck Neil E. , Runge E. C. A.
Published: July 2010

Mollic Albaqualfs in northwestern and west central Illinois occur sporadically in small isolated areas surrounded by Argiudolls and Haplaquolls. A transect was studied to determine (i) if Mollic Albaqualfs are phosphorus deficient relative to the associated weakly developed soils, (ii) dominant forms of phosphorus present in soils at varying stages of development, and (iii) the quantities of vertical and horizontal phosphorus movement within a landscape segment.

Phosphorus availability increases as the degree of profile development increases, which implies that these Albaqualfs have a higher phosphorus‐supplying power than the associated, more productive Argiudolls and Haplaquolls. Fractionation of inorganic phosphorus reveals increasing aluminum, iron, and reductant‐soluble plus decreasing calcium phosphate on progressing toward the Albaqualf end of the transect. Total phosphorus content as well as progressive enhancement of eluvial and illuvial total phosphorus horizons also increases as pedogenetic development increases. Reconstruction of total phosphorus profiles reveals that the most strongly developed Albaqualf has accumulated 493.49 g/m2 of phosphorus whereas the most weakly developed Aquoll has lost 151.34 g/m2. The 1.1‐ha landscape segment studied has incurred a net loss of 188.7 kg of phosphorus. Phosphorus translocations, within the landscape segment studied, greatly aid in explaining the variation in available phosphorus encountered in this transect.
Soil Water Evaporation: Long‐Term Drying as Influenced by Surface Residue and Evaporation Potential
Authors: Bond J. J. , Willis W. O.
Published: July 2010

Evaporation with time was measured from wetted columns of fine sandy loam treated with seven rates of surface residue and subjected to six different evaporation potentials (shaded and unshaded columns in each of three trials). With either shaded or unshaded columns, increasing the rate of soil water evaporation by increasing evaporation potentials or by decreasing rates of surface residue resulted in greater total soil water evaporation after 60 days drying. Surface residue influenced soil temperatures during first and third stage drying and decreased the range between maximum and minimum temperature.
A Comparison of a Large‐Seeded (NC2) and a Small‐Seeded (Starr) Peanut (Arachis hypogaea L.) Cultivar as Affected by Levels of Calcium Added to the Fruit Zone
Authors: Slack T. E. , Morrill L. G.
Published: July 2010

Several greenhouse experiments were conducted to compare various Ca treatments on selected vegetative and reproductive characteristics of Starr and NC2 peanuts. Calcium and K uptake and distribution characteristics in Starr and NC2 peanut plant parts were studied also. Starr and NC2 peanuts were grown in sand cultures with separated rooting and fruiting containers for direct comparisons.

Starr and NC2 peanuts were dependent upon a Ca supply in the fruit zone for proper development of fruit. Starr peanuts produced a larger weight of kernels at low Ca levels than NC2 peanuts. Starr peanuts apparently make more efficient use of Ca for kernel development than the larger seeded NC2 peanuts.
Improvemet of a Solonetzic (Slick Spot) Soil by Deep Plowing, Subsoiling, and Amendments
Authors: Rasmussen W. W. , Moore D. P. , Alban L. A.
Published: July 2010

Soil improvement studies, including deep lowing, subsoiling and gypsum treatments, were conducted on an irrigated solonetzic soil association in southeastern Oregon. The unproductive saline‐sodic (solonetz‐like) soil tentatively classified as Malheur silt loam (with slick spots) and described as a Nadurargid, occurs in complexes with normally leached soils of the Nyssa and related soil series. The saline‐sodic soils were chemically reclaimed in 3 to 4 years by deep plowing 90‐cm deep without gypsum and by deep plowing with gypsum at rates of 18 metric tons/ha (8 tons/acre) and 36 metric tons/ha (16 tons/acre). Crop yields, water intake rates, and water and root penetration were greatly increased by deep plowing. The soils were moderately improved by 36 metric tons/ha of gypsum alone and by subsoiling with gypsum. Subsoiling without gypsum was not beneficial. The results over a 4‐year period indicate that the salt‐affected soils were effectively and most economically reclaimed by deep plowing without gypsum. Deep plowing also improved the productivity and physical conditions of the non‐saline associated soils.
Distribution of Concretions from Selected Soils of the Inner Bluegrass Region of Kentucky
Authors: Phillippe W. R. , Blevins R. L. , Barnhisel R. I. , Bailey H. H.
Published: July 2010

Total iron and manganese was determined on concretions and soil samples by X‐ray emission. Soils studied included Maury, Mercer, and Lawrence, which are well‐drained, moderately well‐drained and somewhat poorly‐drained, respectively. Iron‐Manganese concretions were observed in all horizons, with a maximum of 46% by weight in a Maury C horizon. The Fe/Mn ratios decreased with increasing concretion size. This decrease was largely due to increased Mn content associated with the larger size concretions. Further analyses for composition showed that quartz and clay minerals (vermiculite, montmorillonite, kaolinite, and mica) account for most of the remaining fractions. Traces of titanium and phosphorus were also found. Microscopic studies of the concretions indicated two types of internal fabric; (i) undifferentiated (structureless), and (ii) differentiated or concentric structure. Concretions from the somewhat poorly drained soils are characterized by undifferentiated fabric and diffuse external boundaries. In contrast the concretions from the well‐drained soils are usually spherical, with sharp external boundaries and differentiated fabric.
Effect of Soil Air Movement and Compressibility on Infiltration Rates
Authors: Van Phuc Le , Morel‐Seytoux H. J.
Published: July 2010

The purpose of the study was to determine the hydrologic significance of the soil air flow and of its compressibility in the process of infiltration and moisture redistribution. Results of a numerical solution of the equations describing the simultaneous flow of air and water in a soil are presented. The results show that the air flow and compressibility may affect significantly the infiltration rates and the saturation profiles.
Pore Size Distributions of Soils From Mercury Intrusion Porosimeter Data
Authors: Nagpal N. K. , Boersma L. , DeBacker L. W.
Published: July 2010

Soil water characteristic curves are routinely determined by the pressure plate and pressure membrane techniques. Similar curves can be derived from pore size distribution curves obtained by the mercury intrusion porosimeter technique. Mercury is forced under pressure into previously oven‐dried and evacuated samples. The applied pressure is increased in discrete steps and the volume of pores intruded between pressure steps is obtained. Equivalent pore sizes corresponding to the applied pressures are calculated with the pressure of displacement equation. This technique allows analysis of many samples per day and has therefore an advantage over standard methods.

Soil water characteristic curves of eight soils ranging in clay content from 0 to 57% were determined by the pressure plate and pressure membrane technique and compared with similar curves derived from mercury intrusion data. Results obtained by the two techniques agreed well for soils which do not shrink or swell with changes in water content, but not for samples with swelling clays.
Steady Infiltration from Buried, Surface, and Perched Point and Line Sources in Heterogeneous Soils: I. Analysis
Authors: Philip J. R.
Published: July 2010

The quasilinearized steady infiltration equation is generalized to apply to heterogeneous soils with conductivity depending exponentially on both moisture potential and depth. Mathematical developments, including a theorem connecting surface and buried source solutions, follow closely those established previously for homogeneous soils. Solutions are found for buried, surface, and perched point and line sources. Physically relevant solutions are limited to the following ranges of β, the dimensionless coefficient of dependence of conductivity on depth: for buried and surface sources, β ≥ 0; for perched point sources, β ≤ −1; for perched line sources, β < −1. It is of interest that the homogeneous medium (β = 0) is an extreme case for existence of buried and surface source solutions; and that perched source solutions (relevant to subirrigation) exist only for soils with conductivity increasing rapidly enough with height above the impermeable base. Detailed mapping of flows and general discussion is left to Part 2.
Synthesis of Phenols and Phenolic Polymers by Hendersonula toruloidea in Relation to Humic Acid Formation
Authors: Martin J. P. , Haider K. , Wolf D.
Published: July 2010

Hendersonula toruloidea in glucose or organic residue media produced high yields of a humic acid‐type polymer. As much as one third of the substances, including biomass synthesized by the fungus, consisted of the polymer. The primary phenolic constituents of the polymer are orcinol, 3,5‐dihydroxybenzoic acid, and probably 2,3,5‐trihydroxytoluene with smaller amounts of 2,6‐dihydroxytoluene, m‐hydroxybenzoic acid, 6‐methylsalicylic acid, methylphloroglucinol, salicylic acid, 2,4‐dihydroxytoluene, and several other phenols. Phenols derived from p‐hydroxycinnamic acid were not found. A phenoloxidase was found in mature cells which rapidly oxidized mixtures of the phenols with the formation of polymers. The polymer is highly resistant to microbial degradation in soil and is similar to soil and other fungus humic acids with respect to elemental composition, exchange capacity, and total acidity. The fungus transforms or utilizes numerous phenols as carbon and energy sources.
Factors Influencing Ammonia Losses From Urea Applied to Northwestern Forest Soils
Authors: Watkins S. H. , Strand R. F. , DeBell D. S. , Esch J.
Published: July 2010

Laboratory studies indicated that volatilization losses of NH3 increased with increasing air movement, temperature, and pH of mineral soils and forest floors. At an air flow rate of 3 liters/min (equivalent to calculated air velocity of approximately 0.01 km/hour) and temperature of 19°C, losses were high—ranging from 6 to 30% of the urea N applied to bare mineral soils and 27 to 46% for mineral soils covered by forest floors. Ammonia losses were less for mixtures of NH4Cl and urea crystals than for urea crystals or pellets alone. Losses were not related to urea pellet size.
On the Calculation of Hydraulic Conductivity
Authors: Jackson Ray D.
Published: July 2010

Methods for calculating hydraulic conductivities of porous materials proposed by Marshall and by Millington and Quirk are similar except for the pore interaction term. This term was shown to be a constant for the Marshall method. Using a matching factor, equations for the two methods differ only by the exponent of the pore interaction term, being 0 for Marshall's method and 4/3 for Millington and Quirk's. Data for four porous materials, for which the hydraulic conductivities, pressure heads, and water contents were determined on the same sample, were used in a statistical procedure to obtain a best fit value for the exponent. For the four materials, an exponent of 1 adequately predicted the measured conductivities. With this exponent, hydraulic conductivities for a field soil were calculated from a laboratory‐determined pressure headwater content relation. Calculated and measured conductivities agreed to within the limits of error of measurement.
Clay‐Water Interaction, the Behavior of 3H and 2H in Adsorbed Water, and the Isotope Effect
Authors: Stewart G. L.
Published: July 2010

Reference clay minerals and a field kaolinitic soil were allowed to equilibrate with water tagged with tritium and deuterium. Ratios of tritium and deuterium concentrations of tenaciously adsorbed water to respective concentrations of bulk pore water were approximately equal to one for all soils and clay minerals tested. This suggests that no significant isotopic fractionation occurs in adsorbed water. Thermodynamic theory, relating isotopic fractionation to the energetics of adsorbed water, also predicts that isotopic fractionation is not a function of the energy status of adsorbed water. Data from another experiment, where oven dry samples equilibrated with water vapor in a controlled atmosphere, showed that tenaciously adsorbed water on kaolinitic mineral surfaces is not as labile to exchange with the vapor phase as was adsorbed water on montmorillonite and illite surfaces.
Concentrations and Total Amounts of Nutrients in Citrus Seedlings (Citrus sinensis Osbeck) and in Soil as Influenced by Differential Soil Oxygen Treatments
Authors: Labanauskas C. K. , Stolzy L. H. , Handy M. F.
Published: July 2010

This greenhouse experiment was conducted to evaluate the soil oxygen effects on concentrations and total amounts of nutrients in citrus seedlings (Citrus sinensis Osbeck) and in the soil medium in which the plants were grown.

Reduction in amount of soil oxygen to the roots significantly decreased N, P, K, Ca, Mg, Zn, Cu, Mn, B, and Fe concentrations in the leaves, and increased these elements in the roots. A significant increase in concentration of Na, Cl, and N, and a decrease of K, Ca, and Mg in the stems was caused by the low level soil oxygen.

Total amounts of P, K, Ca, Mg, Cl, Zn, Cu, Mn, and B per whole plant were significantly lower when grown under the low soil oxygen supply. Soils supplied with low levels of soil oxygen contained higher concentrations of NO3‐N and Ca than soils treated with the normal level of soil oxygen.

Low level soil oxygen resulted in an increase in Na and Cl concentrations in the stems only, and not, as had been previously assumed, in the leaves.

Soil oxygen effects on the uptake and translocation of nutrients in plants cannot be assessed solely on the basis of the nutrient concentrations in the plant leaves. Consideration of plant dry weight and total mineral content per plant are essentials in studying the experimental relationship of soil oxygen to the plant nutritional status.
The Effect of Ammoniacal Nitrogen on Lettuce (Lactuca sativa) and Radish (Raphanus sativus) Plants
Authors: Weir B. L. , Paulson K. N. , Lorenz O. A.
Published: July 2010

The relationship of the growth of radish and lettuce plants to pH, NH3, and NH4+ concentration of the nutrient solution was determined by the use of stepwise multiple regression. Data were collected from plants grown in nutrient solutions with a factorial arrangement of pH (6, 7, and 8) and ammonical nitrogen (0, 10, 20, 30, 40, 60, and 90 ppm of N). The equations obtained for radish and lettuce, respectively, were: Y = 0.479 + 0.00242 X13 + 0.0207 X2 − 0.605 X3 + 0.0133 X33 + 0.0200 X4 − 0.000746 X42 + 0.00000551 X43 and Y = 5.571 − 0.551 X1 − 0.00111 X23 − 0.605 X3 + 0.0171 X33 + 0.0428 X4 − 0.000753 X42 + 0.00000327 X43 where Y was grams of dry matter/plant, X1 was pH, X2 was H+ cone x 107, X3 was NH3 conc. (ppm of N) and X4 was NH4+ conc. (ppm of N). Both equations were significant at the 0.5% level and had R2's of 0.575 and 0.646, respectively. The response of the two species to pH and H+ differed, with radish having its optimum growth at pH 8 and lettuce at pH 7. Their responses to NH3 and NH4+ were very similar. Growth was reduced as the NH3 conc. increased and was increased as the NH4+ conc. increased to an optimum level of 17 ppm of NH4+‐N for radish and 36 ppm for lettuce.
A Study of the Uniqueness of the Soil Moisture Characteristic During Desorption by Vertical Drainage
Authors: Vachaud Georges , Vauclin Michel , Wakil Michel
Published: July 2010

Previous experiments concerning the desorption of a horizontal column of uniform soil suggested that the moisture characteristic was not unique throughout the column. Further desorption experiments have been carried out on a vertical column. The results are consistent with those obtained previously, and give further information on the dual dependence of ψ on θ and on ∂ψ/∂t.
Hydraulic Conductivity Evaluation of the Soil Profile from Soil Water Retention Relations
Authors: Bruce R. R.
Published: July 2010

Evaluation of the water content‐suction relation applicable to field soil horizons that differ widely in texture was considered. Except for coarse‐textured, organic matter‐deficient horizons, it is concluded that soil water retention of sieved samples is significantly modified and does not represent the natural soil volume. Water content‐suction data from measurements on carefully procured core samples of each horizon of a Typic Hapludult adequately represent their water retention characteristics. Using appropriate water content‐suction data, the hydraulic conductivity‐water content relation calculated by published procedures was compared with hydraulic conductivity measured on similar samples by a transient outflow procedure. The calculated hydraulic conductivity‐water content relations for coarse grained systems or systems having a relatively narrow range of pore size and well‐defined bubbling pressure was sufficiently accurate for many purposes. However, to obtain a useful evaluation of the unsaturated hydraulic conductivity of fine‐textured horizons with a very wide range of pore size and a poorly defined bubbling pressure, the Marshall or Millington and Quirk methods had to be matched at a water content in the 0.1‐ to 0.3‐bar range. Indiscriminate use of such methods of calculating hydraulic conductivity is inadvisable.
Potassium‐Calcium Exchange Coefficients in Clay Fractions of Some Vertisols
Authors: Knibbe W. G. J. , Thomas G. W.
Published: July 2010

Potassium‐calcium exchange equilibria of the following representative Vertisols were determined: Houston Black, Montell, Beaumont, and Houston. Wyoming bentonite and the clay from a Miller soil were included for comparison. Exchange equilibria were expressed in terms of the Gapon equation. The Gapon coefficient KG of the soil clay fractions at high (>18%) K‐saturation were 4 to 5 times higher than for Wyoming bentonite and increased sharply with decreasing K‐saturation. On the basis of X‐ray diffraction data and total K analyses, it was concluded that the highly montmorillonitic clay fractions are interstratified with mica. Specific surface areas were determined relative to Wyoming bentonite. Charge densities (Γ) were expressed as the ratio's Γ soil clay/Γ Wyoming bentonite.

Differences in the affinity for K at low K‐saturation were closely related to mica content. The shape of the KG vs K‐saturation curves was explained by the hypothesis that three different sites are available for K adsorption: edge‐interlayer sites of mica, wedge‐shaped sites which might easily form between mica‐montmorillonite layers with graded K selectivities, and planar sites mainly on the montmorillonite.

Total chemical analyses of the fine clay fraction of Houston Black and Montell indicated that the high charge density originates mainly in the octahedral layer.
Fertilizer Responses in Young Pine Plantations
Authors: Pritchett W. L. , Smith W. H.
Published: July 2010

Regional fertilizer trials were installed in 28 young pine plantations in the US Lower Coastal Plains in 1968. Three randomized complete blocks consisting of a 32 + 2 factorial experiment were included at each site. Soil samples were collected to help characterize the sites physically, chemically, and biologically. Site preparation, planting and fertilization methods were uniform from site to site. Survival was influenced by site properties and fertilizer treatment. On well‐drained sites N reduced survival. Height growth response varied from none on dry sands to as much as 130% increase on some wet sites. Nitrogen significantly affected tree growth in 53% of the tests; but on P deficient sites, N applied alone had little influence on tree growth. Phosphorus additions increased growth in 63% of all tests and 82% of the tests located on poorly‐drained sands. The number of trees damaged by tip moths (Rhyacionia spp) averaged 10% or more in only 18% of the tests. In these experiments, P and K applications apparently reduced the number of trees attacked. Almost 22% of the trees in all tests were infected with Cronartium fusiforme Hedge. However, 40% of the tests had less than 5% infection. In tests where rust was severe, the percentage of rust‐infected trees increased with fertilization. Fertilization, especially with K, appeared to reduce insect attacks. Species composition of the ground cover was altered by treatments.
The Relationship of Red Pine Site Index to Soil Phosphorus Extracted by Several Methods
Authors: Alban David H.
Published: July 2010

Phosphorus was extracted by 10 methods from soils in Minnesota supporting stands of red pine (Pinus resinosa Ait.) to find those methods most suitable for estimating site index. The amount of phosphorus extracted from the surface 25 cm of mineral soil by H2O, 0.002N H2SO4, or 0.01N HCl was related at the 1% level (r2 = .47 to .53) to site index. Considerably weaker relationships with site index were obtained with organic P, total P, and phosphorus extracted by 0.5N NaHCO3, 0.4N HCl, 0.025N HCl + 0.03N NH4F, 0.10N HCl + 0.03N NH4F, or 0.05N HCl + 0.025N H2SO4. No improvement in the estimation of site index was made by including phosphorus extracted from deeper layers of the soil. Foliar phosphorus concentration was significantly related to site index and to the amount of phosphorus extracted from the surface soil by H2O, 0.002N H2SO4, or 0.01N HCl.
Substances Contributing to Fire‐Induced Water Repellency in Soils
Authors: Savage S. M. , Osborn J. , Letey J. , Heaton C.
Published: July 2010

A soil susceptible to heat‐induced water repellency was heated at several temperatures and oxygen concentrations. The materials emanating from the heated soil were captured and their mass determined. The greatest quantity of products was captured at temperatures above 300C. Increasing amounts of material were produced with increasing oxygen concentrations up to 20%. From 0.3% to 1.75% of the total soil was captured as products.

Fractionation of these captured products by adsorption chromatography resulted in the isolation of several different components. Three of these components were capable of causing extreme water repellency in sand if the treated sand were heated. Some evidence suggested that the heating of these substances on the sand surfaces altered their structure. These three effective components represented from 25–50% of the total materials collected from the soil.

Elemental and spectroscopic analyses of the effective components indicated them to be basically aliphatic hydrocarbons.

The undecomposed and partially decomposed plant materials present in the soil were determined to be the primary source of the products coming from the heated soils.
Pyrophosphate Hydrolysis in Soil as Influenced by Flooding and Fixation
Authors: Racz G. J. , Savant N. K.
Published: July 2010

The rate of hydrolysis of pyrophosphate (K4P2O7) in a noncalcareous soil maintained at field capacity moisture content or under flooded conditions was determined. Attempts were also made to study the influence of fixation of added pyrophosphate by soil on the rate of pyrophosphate hydrolysis. The initial rate of pyrophosphate hydrolysis was rapid and approximately the same for both flooded soil and soil maintained at field capacity moisture content. The first‐order reaction rate constants, obtained by plotting the log of the concentration of unhydrolyzed pyrophosphate vs. time were 8.14 × 10‐4 min‐1 and 8.37 × 10‐4 min‐1 for soil at field capacity and under flooded conditions, respectively. However, after about 3 days of incubation, flooded soil hydrolyzed pyrophosphate at a relatively greater rate (k = 2.0 × 10‐5 min‐1) than did soil maintained at field capacity (k = 1.3 × 10‐5 min‐1). This difference appeared to be due to an increase in pyrophosphatase activity in the flooded soil. The half‐life of the added pyrophosphate was approximately 2 days.

Pyrophosphate adsorbed by an anion exchange resin or fixed by soil hydrolyzed at a slower rate than did pyrophosphate in solution. The ratio of orthophosphate to total phosphate (orthophosphate + pyrophosphate) extracted from phosphated soils by various extractants decreased in the order: water, 0.1N H2SO4, and 0.5N H2SO4. Water‐soluble or loosely bound pyrophosphate hydrolyzed at a much greater rate than did water‐insoluble or strongly bonded pyrophosphate.
Diffusion of Selected Herbicides in Soil
Authors: Don Scott H. , Phillips R. E.
Published: July 2010

Diffusion coefficients of atrazine, simazine, prometone, prometryne, 2,4‐D, chlorpropham, diphenamid, fluometuron, trifluralin, and benefin, were measured in Lanton silty clay loam. The effects of soil moisture content and adsorption upon the diffusion coefficients were evaluated.

Differences were observed in the magnitude of diffusion coefficients of the 14C‐labeled herbicides in the soil. The self‐diffusion coefficients of 2,4‐D, chlorpropham, diphenamid, and prometone decreased as diffusion time increased, which suggest that changes in the structure of these herbicides might have occurred. The self‐diffusion coefficients of fluometuron, atrazine, simazine, prometryne, trifluralin, and benefin were found not to be significantly changed as diffusion time increased.

The rate of diffusion increased as the soil water content increased for all herbicides except trifluralin. Diffusion of trifluralin was higher at the lower moisture content and this was attributed to a greater amount of trifluralin moving in the vapor phase.

Linear adsorption isotherms were obtained with all herbicides. The order of adsorption was 2,4‐D < fluometuron ≃ prometone < simazine ≃ atrazine ≃ diphenamid < prometryne ≪ chlorpropham ≪ trifluralin ≪ benefin. Correlation analysis showed that the diffusion coefficients of the nonvolatile herbicides were inversely related to the amount of adsorption indicating that most of the diffusion occurred in the solution phase. For those herbicides that are considered to be volatile, diffusion occurred in the vapor phase and the solution phase.
Equilibrium Relationships of Metal Chelates in Hydroponic Solutions
Authors: Halvorson A. D. , Lindsay W. L.
Published: July 2010

Stability‐pH diagrams were developed to describe the equilibrium relationships of metal ions with chelating agents in nutrient solutions for the following chelating agents: EGTA, EDTA, DTPA, CDTA, and EDDHA. These stability diagrams give the concentration of each chelated metal species in solution in the pH range of 4 to 9 and provide a reliable means for selecting appropriate chelating agents for specific purposes. With increased pH, displacement of Fe3+ from the following chelating agents by divalent cations is in the order EGTA > EDTA > DTPA > CDTA > EDDHA. Similar developments can be extended to other chelating agents and to nutrient solutions of different composition.
The Determination of Quinone Groups in Humic Substances
Authors: Schnitzer M. , Riffaldi R.
Published: July 2010

The reduction of quinone groups in humic substances by acid SnCl2 solution was found to be unsatisfactory. The experimental conditions are drastic, the systems are heterogeneous, favoring adsorption or complexing of the reducing agent by the humic materials, and so leading to excessively high quinone values.

Reduction of humic substances by SnCl2 and Fe2+‐triethanolamine in alkaline solution at room temperature and atmospheric pressure appeared to be more suitable for the determination of quinone groups in these materials. There was good agreement between quinone groups determined by the two methods on seven humic and one fulvic acid. The quinone group content of the humic acids analyzed ranged from 1.4 to 2.2 meq/g, that of the fulvic acid was < 1.0 meq/g.

No correlation was found between quinone groups and the free radical content of the humic materials. The results suggest that quinone groups in humic substances form part of complex chemical structures and not of simple compounds.

The determination of quinone groups in humic substances is difficult because of the presence of substantial amounts of CO2H, OH, and ketonic C=0 groups, some or all of which may interfere. Thus, it is advisable to check each analysis by at least two different methods.
Uptake of Phosphorus by Plants Growing Under Field Conditions: II. Computed and Experimental Results for Corn Plants
Authors: Bar‐Yosef B. , Bresler E. , Kafkafi U.
Published: July 2010

Fluxes of P uptake by corn (Zea mays L.) plants growing in the field under high and low P fertilization levels, were both predicted by an uptake model, and obtained experimentally in the field by a new technique.

The computed fluxes were averaged over a period of 1 week to give values of 4.8 × 10‐5 and 1.7 × 10‐5 µg P cm‐2 sec‐1 at the high and low P levels in the soil, respectively. These values were lower than the experimental weekly average fluxes which, at the critical growth period (between the 5th and 7th weeks), equaled about 6.8 × 10‐5 and 2.5 × 10‐5 µg P cm‐2 sec‐1, correspondingly. The deviation of the real conditions prevailing in the field from those assumed in the model tended, qualitatively, to explain the discrepancy.

It is shown that the computed flux of P uptake is more sensitive to variations in the soil than in the plant parameters.
Vertical Mulch Effects on Soil Water Storage
Authors: Fairbourn Merle L. , Gardner H. R.
Published: July 2010

Soil water storage for vertical mulch and furrow treatments on level soil surfaces and vertical mulch and nonmulch treatments with microwatersheds was evaluated in a constant temperature laboratory. The vertical mulch treatment on a level surface saved 30 to 40% more of the applied water than the furrow treatment. The efficiency of storage with vertical mulch was reduced by 17% when the surrounding soil surface was wet during water application. A microwatershed with vertical mulch stored 7 to 10% more of the applied water than a microwatershed without mulch. Depth of water infiltration and dry soil surface adjacent to the mulch appeared to be the factors that reduced evaporation losses from vertical mulch treatments. A comparison of scaled evaporation data with the diffusivity curve for the soil used demonstrated that the diffusivity equation was useful for predicting soil water loss by evaporation for microwatershed treatments of this experiment.
Cristobalite and Quartz Isolation from Soils and Sediments by Hydrofluosilicie Acid Treatment and Heavy Liquid Separation
Authors: Henderson J. H. , Clayton R. N. , Jackson M. L. , Syers J. K. , Rex R. W. , Brown J. L. , Sachs I. B.
Published: July 2010

A qualitative method for the isolation of cristobalite or of quartz from soils and sediments was developed for the characterization of these SiO2 polymorphs by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and oxygen isotope analysis by mass spectrometry. The procedure, applicable to silt or sand size fractions, involved two steps. First the quartz was separated from the cristobalite by centrifugation of a polyvinylpyrrolidone (PVP) stabilized suspension in tetrabromoethane and nitrobenzene mixtures (specific gravity range from 2.28 to 2.38). Then selective chemical dissolution of the non‐SiO2 minerals was effected by HCl, NaOH, and H2SiF6 treatments. Minerals, such as magnetite, resistant to dissolution in these reagents, were subsequently removed by heavy liquid separation.

Treatment of hydrothermal low‐cristobalite (Taiwan), having blocky SEM masses and δ18O = 14 ‰, with HCl, NaOH, and H2SiF6 removed amorphous silica and released the crystalline platelets of δ18O = 9 ‰. Little change in isotope abundance of the latter occurred on retreatment. When amorphous diatom skeletons (δ18O = 32.2 ‰) were treated with these reagents, 77% of the sample dissolved. The remaining skeletons had slightly lower δ18O value (29.1 ‰) but a similar diatom skeleton morphology by SEM.

Quartz isolated from the A2 and Cl horizons of Parahaki soil of New Zealand had δ18O values of 9.6 to 10.0 ‰ The associated low‐cristobalite had δ18O = 8.3 to 9.1 ‰. The oxygen isotope data indicate that both of these SiO2 polymorphs had a hydrothermal or volcanic origin, and were not formed in the soil.