bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxic Metals in Acid Soil: II. Estimation of Plant‐Available Manganese
Authors: Hoyt Paul B. , Nyborg Marvin 
Published: July 2010

AbstractManganese in 40 acid surface soils was measured by eight methods and statistically compared with the concentrations of Mn in barley (Hordeum vulgare L.), turnip rape (Brassica campestris L.), and alfalfa (Medicago sativa L.) grown on the soils in a greenhouse study. Of the eight methods, a 16‐hr extraction with 0.01M CaCl2 gave by far the best estimate of plant‐available Mn, the correlation coefficients being 0.76, 0.73, and 0.86 between Mn extracted from the soil and the concentrations of Mn in barley, rape, and alfalfa, respectively. Another form of soluble Mn, that extracted by 0.1N HOAc, gave the next best estimate of plant‐available Mn. The other five extraction methods, consisting of 0.1N H3PO4 or 0.002N HCl for soluble Mn, 1N KCl or 1N NH4OAc (pH 3) for exchangeable Mn, and 0.2% hydroquinone in 1N NH4OAc (pH 7) for easily reducible Mn, gave fair to poor estimates of available Mn. Total Mn gave a poorer estimate than did any of the methods used for extractable Mn. On arranging the soils in two groups of equal number, having pH ranges of 4.15–5.14 and 5.15–5.63, good measurements of available Mn in both groups were given by only the 0.01M CaCl2 method.Manganese in the three plant species was correlated with soil pH but not with percent base saturation. Besides being related negatively to soil pH, Mn in the plants also was related positively to total soil Mn and negatively to soil exchange capacity as shown by multiple regression analyses.
s‐Triazine Adsorption Studies: Ca‐H‐Humic Acid
Authors: Gilmour J. T. , Coleman N. T. 
Published: July 2010

AbstractSmall amounts of Ca‐H‐humic acid suspension in dialysis bags were immersed in dilute CaCl2 which contained 1.33 × 10‐5M to 6.67 × 10‐5M atratone, atrazine, prometone, or prometryne. Adsorption isotherms were linear. Increases in CaCl2 concentration from 10‐4M to 10‐2M or larger Ca saturation (10 to 100% Ca) of humic acid resulted in less s‐triazine adsorption. Greater adsorption occurred when the amount of Ca‐humate at a specified Ca saturation was increased. An ionexchange treatment of adsorption quantitatively predicted adsorption changes with change in s‐triazine concentration, CaCl2 concentration, and Ca saturation of the humic acids.
The Cause of the Suspension Effect in Resin‐water Systems
Authors: Olsen R. A. , Robbins J. E. 
Published: July 2010

AbstractTwo hypotheses persist regarding the cause of the suspension effect. The traditional hypothesis attributes the effect to a different activity of ions in the suspension than in the dialyzate. The alternative hypothesis attributes the effect largely to a junction potential at the calomel‐suspension boundary. Data obtained by means of three independent methods in this investigation indicate that the latter hypothesis is correct. A potentiometric technique indicated that activities of chloride ions cannot be reliably measured directly in resin‐water systems due to the uncertainty of a junction potential which may be negligibly small or may be as high as several hundred millivolts. Osmotic pressure and freezing point determinations provided confirmatory evidence that the activity of ions was virtually identical in slurry and dialyzate even though the suspension effect was exceptionally large.
Effect of Ammonium and Nitrate Fertilization on Phosphorus Uptake as Related to Root‐Induced pH Changes at the Root‐Soil Interface
Authors: Riley D. , Barber S. A. 
Published: July 2010

AbstractSoybeans (Glycine max L.) fertilized with either NH4‐N or NO3‐N were grown in a growth chamber using soil with four different initial pH levels. Liming the soil used in this research to increase pH decreased the P level in solution. Fertilization of soybeans with NH4‐N decreased the pH of the rhizocylinder (root plus strongly adhering soil); fertilization with NO3‐ increased rhizocylinder pH. The difference between the rhizocylinder pH of the NH4+ and NO3‐ treatments was as large as 1.9 pH units with an initial soil pH of 5.2 and as small as 0.2 units when soil pH prior to N application was 7.8.Ammonium‐fertilized soybeans absorbed more P and had a higher P concentration than NO3‐fertilized soybeans. The results for soybeans grown with NH4+ and NO3‐ treatments at four initial soil pH levels showed that the P content of the shoots and roots was closely correlated with the pH of the rhizocylinder, but not the pH of the bulk soil. This suggests that the increased availability of P from the soil where NH4+ was used was mainly due to the effect of the nitrogen source on the pH of the rhizosphere soil.Soybean root length decreased from 180 to 120 m/gram of dry roots as the pH of the rhizocylinder increased from 4.7 to 7.5.
Factor Analysis and Numerical Taxonomy of Soils
Authors: Arkley Rodney J. 
Published: July 2010

AbstractA large computer and multivariate statistics were used to select a minimal number of soil properties with the greatest prediction value for use in soil classification. Key communality cluster analysis and principal axis factor analysis with Varimax rotation were applied to six sets of soil data containing from 21 to 66 profile characteristics. The analyses selected from four to seven factors or dimensions which were highly independent of each other and contained from two to four highly correlated soil properties. These factors accounted for 100% of the communality and 90% of the raw variance in all properties used in each set. In spite of the diversity of the soils (220 and 620 California, 59 and 86 World, and 148 Ohio soils) the same factors appeared repeatedly; i.e., properties related to reaction, hue and chroma, texture, color value and mottling, and profile differentiation in five analyses and solum thickness in four. Composite factor scores computed for each soil were also used for Numerical Taxonomy. The groupings formed were sufficiently similar to those of the New Classification System of the USDA to suggest that these methods may be very useful in soil classification. The use of these methods for the development of a coordinate system of soil classification is discussed.
Water‐soluble NO3‐Nitrogen, PO4‐Phosphorus, and Total Salt Balances on a Large Irrigation Tract
Authors: Carter D. L. , Bondurant J. A. , Robbins C. W. 
Published: July 2010

AbstractReturn flow from a 82,030‐ha (202,700‐acre) tract of calcareous silt loam soils irrigated with water diverted from the Snake River in southern Idaho increased the downstream total soluble salt and NO3‐N loads, but decreased the downstream PO4‐P load. Under the existing water management practice, 50% of the total input water returned to the Snake River as subsurface drainage. Net total soluble salt output was 2.4 metric tons/ha (1.0 English ton/acre) and, on the average, was considerably greater than necessary to maintain a salt balance. Net NO3‐N output was 33 kg/ha (30 lb/acre). Only about 30% as much PO4‐P left the tract via drainage water as entered the tract in irrigation water. As water passed through the soil, PO4‐P was removed by chemical reactions in the soil, thus decreasing the concentration in the subsurface drainage water and decreasing the downstream PO4‐P load. Applied P fertilizer was not leached into the drainage water.
Auger Hole Seepage Theory
Authors: Boast C. W. , Kirkham Don 
Published: July 2010

AbstractWe 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

AbstractProteins (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

AbstractThe 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

AbstractThe 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

AbstractCommon 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

AbstractFall 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

AbstractThe 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.
Soil Temperature Estimation by a Numerical Method
Authors: Hanks R. J. , Austin D. D. , Ondrechen W. T. 
Published: July 2010

AbstractA 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

AbstractComparisons 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

AbstractInsight 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

AbstractDepth 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

AbstractSpatial 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

AbstractA 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

AbstractDDT 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.