bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil Water Relations During Rain Infiltration: II. Moisture Content Profiles During Rains of Low Intensities
Authors: Rubin J. , Steinhardt R. , Reiniger P.
Published: July 2010

During transient‐state infiltration of steady, low intensity rain into laboratory soil columns, moisture contents at increasing soil depths tended with time to approach a constant level. This level, as well as the observed rates of wetting‐front advance, were higher in cases of more intense rain. For the conditions studied, soil moisture contents and wetting‐front advance rates associated with ponded‐water infiltration were generally considerably higher than those of rain infiltration profiles.

The differences between the observed and the theoretically predicted rain infiltration profile data were insignificant for rains of low intensity but significant for those of higher intensity. The wetting front advance observations confirmed certain aspects of the theory presented in part I of this paper.
Nitrogen Transformations in Soil as Related to Structure, Moisture, and Oxygen Diffusion Rate
Authors: Brandt G. H. , Wolcott A. R. , Erickson A. E.
Published: July 2010

The aeration status of a Brookston clay loam was varied by varying aggregate size, moisture content, and moisture tension. Moisture tensions ranged from saturation to about field capacity. Determinations for pH, NH4+, NO3‐ and oxygen diffusion rate were made periodically during 2 months' incubation at 35°C. Oxygen diffusion rate was determined amperometrically, using platinum electrodes 4 mm. long by 0.8 mm. in diameter. Average rates associated with aggregate size and moisture content ranged from 3 to 43 g. O2 × 10‐8 cm.‐2 minute‐1.

Fluctuations in oxygen diffusion rate with time paralleled changes in concentrations of NH4+ and NO3‐ and appeared to reflect changes in metabolic demand for oxygen by components of the microbial population other than the nitrifiers.

Large discrepancies between NH4+ disappearance and NO3‐ accumulation made it necessary to distinguish between nitrification as the biological oxidation of reduced forms of nitrogen and net nitrification as the observed accumulation of nitrate.

Net nitrification varied with apparent delay period and rate of NH4+ oxidation, and with losses of nitrified N. Rates of ammonium oxidation were related directly to the general level of oxygen supply as measured grossly with the platinum electrode. Apparent delay periods were influenced primarily by anaerobic metabolism in microenvironments too small to be differentiated by the electrodes which were used. Mineral N deficits appeared to be due primarily to enzymatic denitrification at oxygen diffusion rates less than 20; at higher levels of oxygen supply, chemical instability of NO2‐ appeared to become increasingly important because of an accompanying decrease in pH.
Dioctahedral Vermiculite and Chlorite in Highly Weathered Red Loams in Victoria, Australia
Authors: Jones L. H. P. , Milne A. A. , Attiwill P. M.
Published: July 2010

Red loams from an old divide in Victoria, Australia, have been examined by optical, X‐ray diffraction, chemical, and thermal methods. The soils have developed on intrusive granodiorite and associated metamorphosed Silurian rocks. The clay fractions of the surface soils on the metamorphosed rocks contained dioctahedral vermiculite with interlayer alumina and the clays of the surface soils on the granodiorite contained dioctahedral chlorite. The chlorite decomposed when heated between 300° and 400°C. which corresponds to the temperature at which gibbsite decomposes. The chlorite also decomposed when treated (with KOH and KCl) to remove interlayer alumina. The weathering in the red loams is correlated with the mineralogy of the sand fractions and the parent rocks.
The Streamline Function for Axially Symmetric Groundwater Movement
Authors: Zaslavsky Dan , Kirkham Don
Published: July 2010

The equation for the stream function for axially symmetric potential flow of groundwater is derived. The equation is illustrated by obtaining the streamlines for flow into an auger hole as used for hydraulic conductivity determination of soil.
Buffer Curves of Acid Clays as Affected by the Presence of Ferric Iron and Aluminum
Authors: Coleman N. T. , Thomas G. W.
Published: July 2010

Buffer curves of Al‐ or Fe‐montmorillonites and hectorite in 1.0N KCl had appreciably smaller slopes between pH 5 and 8.5 than did curves for corresponding H‐clays. Aluminum or ferric hydrous oxide‐clay complexes gave buffer curves indicative of almost no exchangeable Al, Fe, or H on permanent‐charge sites, but rather showed a regular increase in pH with additions of NaOH. The behavior of the clay‐sesquioxide complexes is thought due to the existence, at pH below about 5, of hydroxy‐Al or Fe‐ions on exchange sites, with the progressive conversion of these to the corresponding hydroxides upon the addition of base. That such a reaction can result in apparent pH‐dependent cation‐exchange capacity (CEC) was shown by the reasonably good correspondence between CEC's measured at various pH values and the amounts of base necessary to titrate the complexes to those pH's. It is suggested that the pH‐dependent CEC's of some soils may be due to the presence of clay‐sesquioxide complexes. In other cases, apparent pH‐dependent exchange capacity can be “created” during the neutralization of Al‐ or Fe‐clay, through the interaction of positively charged metal ion‐hydroxy complexes with exchange sites. Aluminum‐ or Fe‐hydroxy complexes with montmorillonite were not stable upon digestion in dilute salt solutions, but underwent dismutation to produce the corresponding metal ion and hydroxide. While sesquioxide‐montmorillonite complexes resembled many acid soils so far as titration behavior and pH‐dependent CEC are concerned, the chlorite‐like complexes were far less stable than those found in soils.
Phosphorus and Zinc Concentrations in Russet Burbank Potato Tissues in Relation to Development of Zinc Deficiency Symptoms
Authors: Boawn Louis C. , Leggett G. E.
Published: July 2010

Russet Burbank potatoes were grown on field plots and in nutrient solutions at levels of Zn and P nutrition that would produce plants ranging from no Zn deficiency to severe Zn deficiency.

Increasing the supply of P induced a growth disorder that could be eliminated by an increased supply of Zn. Neither the development of the deficiency nor the elimination of the deficiency was well correlated with changes in the concentration of Zn in stem and leaf tissues. High concentrations of P in tissues resulting in high P/Zn concentration ratios appear to offer a better explanation for the metabolic upset. Healthy plants tended to have P/Zn concentration ratios < 400, whereas in deficient plants the ratio was generally > 400.

The data obtained indicate a mutual antagonism between P and Zn in their uptake and accumulation in the plant.
Field Experiments on Sealing Permeable Fine Sand With Bentonite
Authors: Rollins M. B. , Dylla A. S.
Published: July 2010

Bentonite has excellent sealing powers. Treating permeable fine sand with bentonite saved up to 99% of the water previously lost through seepage. From less than 1 up to 2 pounds of bentonite per square foot of sand surface was applied by adding a prepared bentonite suspension to the water or by mixing it dry with the sand.

After drying for 1 month and then rewetting, the seals were 75 to 80% effective. Winter weather and particularly severe winds damaged the bentonite seals still further, reducing them to between 30 and 60% effectiveness. At the close of 2 years of experimentation, including five wetting and drying cycles, the bentonite seals were 27 to 44% effective.

It is estimated that one bentonite seal would cost about the same as the annual cost of 4 inches of concrete amortized over a 30‐year period at 6% interest. Therefore, bentonite does appear favorable as a competitive sealer, since one application of bentonite may be effective for more than 1 year.

Simple and effective methods of establishing bentonite seals must be further developed before this sealing method can be fully utilized to effectively reduce seepage losses.
Seepage into Stratified Water‐Saturated Soil from Idealized Vertical Mulch Channels
Authors: Swartzendruber Dale
Published: July 2010

A general theoretical method of approximating the steady‐state, two‐dimensional seepage rate in stratified porous media is applied to the problem of water flow into stratified water‐saturated soil in the presence of idealized subsoil channels. The approximation, for the present problem estimated to be accurate within 10%, is obtained by considering the stratified system in 3 special, mathematically degenerate cases for which exact solutions are available. When a less permeable surface soil stratum overlies a more permeable stratum, the flow effect of the channels always exceeds that found for channels in a uniform soil and becomes quite marked if the channels penetrate the upper, less permeable stratum and extend into the more permeable stratum below. If the more permeable stratum overlies the less permeable stratum, the flow effect of the channels is less than in a uniform soil.
Ammonia and Ammonium Reactions with Some Layer‐Silicate Minerals
Authors: Young J. L. , McNeal B. L.
Published: July 2010

Retention of NH3 and fixation of NH4+ by 16 specimen layer‐silicate minerals was investigated using anhydrous and aqua NH3, NH4Cl, and different degassing and fixing conditions.

Despite a much greater partial pressure differential, vacuum degassing (to remove excess and physically sorbed NH3) greatly accentuated the retention and apparent NH3 fixation as compared with diffusion degassing.

The great bulk of NH3 initially sorbed by anhydrous NH3‐treated layer‐silicates was rapidly dissipated (few hours to < 3 days) when samples were exposed to the atmosphere. Redisplacement by competitive water vapor evidently was a principal driving force. The equivalent of tons of NH3 per acre‐furrow‐slice, however, was retained longer than 3 days by the expandable layer‐silicates. The major portion (68 to 99+%) of retained NH3 was KCl leachable in all except the vermiculitic samples in which > 90% was fixed.

Wide variability in basal spacing changes resulted from ammoniation and wetting treatments. Physical changes as reflected by X‐ray diffraction were in general accord with chemical data.

Vermiculitic minerals under wet or air‐dry conditions fixed quantities of NH4+ greatly in excess of amounts fixed by other minerals. Metabentonite 38 and biotite 33 fixed moderate quantities under these conditions.

In a comparison of N sources under wet fixing conditions, less than 20% as much N was fixed by vermiculite from aqua NH3 as from NH4Cl. All other minerals fixed roughly equivalent amounts from both sources.

Montmorillonites fixed very small quantities of NH3 or NH4+ under wet or air‐dry conditions but showed a roughly 20‐fold increase in NH4+ fixation resulting from drying at 105°C.

Anomalous retention and mechanisms of NH3 retention and fixation are briefly discussed. Results re‐emphasized need for continued restraint to minimize overextrapolation of data from a few type minerals to complex mixtures as generally encountered in soils.
Contrasting Release Characteristics of Potassium in Alluvial and Associated Upland Soils of Indiana
Authors: Binnie R. R. , Barber Stanley A.
Published: July 2010

The uptake of K from alluvial soils was similar to that from associated upland soils under low cropping intensity. Under the high intensity cropping of a Neubauer experiment, the alluvial soils released more K. Within the exchangeable K range 40 to 180 ppm., K uptake was 67 ppm. greater from the alluvial soils than from the associated upland soils at the same exchangeable K level. The reduction of exchangeable K in the soil due to crop removal was greater in the upland than in the alluvial soils. There was no statistical correlation between the mineralogical composition of the soil and the K released.
Relationships between Ammonia Volatilization, Ammonia Concentration and Water Evaporation
Authors: Chao Tyng‐Tsair , Kroontje Wybe
Published: July 2010

The rate of NH3 volatilization and the rate of water evaporation from soils followed different functions. These functions were not affected by differences in soil texture, soil water, speed, or relative humidity of air flowing over the soil surface. A linear relationship was observed between the rate of NH3 applied (up to 600 ppm.) and NH3 volatilized. The NH3 losses from finer textured soils were proportional to their original soil pH's. The larger NH3 losses from the coarse textured soil indicate that soil texture is a key factor in NH3 volatilization.
The Influence of Root Zone Temperature on the Growth and Contents of Phosphorus and Anthocyanin of Corn
Authors: Knoll H. A. , Lathwell D. J. , Brady N. C.
Published: July 2010

In a greenhouse experiment corn plants were grown in sand cultures using a complete nutrient solution in which only the P level varied. Root zone temperatures of 15°, 20°, and 25°C. were used in this experiment. In addition, 2 weeks after emergence, a number of plants were subjected to a sudden change in root zone temperature. The dry weight yield and the P content of the tops and the roots and the anthocyanin content of the tops were determined at 2 and 3 weeks.

Low root zone temperature severely restricted the growth of young corn plants. High P levels never fully counteracted this harmful effect. It was likely that reduced P uptake at low root zone temperature was caused primarily by a depression in root growth, induced by the low root zone temperature. Anthocyanin synthesis was stimulated by both a low root zone temperature and a low P level in the nutrient solution indicating that purpling of corn is not necessarily an indication of P deficiency.
Effects of Parent Material and Vegetation on Properties Related to Soil Erosion in Central Washington
Authors: Wooldridge David D.
Published: July 2010

In a preliminary study of physical properties of wild land soils, three soil parent materials were sampled by horizons under forest and adjacent grass cover. Soil properties analyzed were mean water‐stable aggregate, bulk density, organic matter pH, total porosity, and % clay, silt, and sand. Several of the measured soil properties were related significantly to parent material and horizon depth. Effects of vegetative cover were not reflected in overall averages of soil property values. However, these values, broken down by parent materials and horizons, indicated that forest and grass covers were associated with soil property differences, although the relation of these differences to changes in parent materials and horizons is not consistent. Over 40% of the variation in soil erosion hazard (as measured by mean size of water‐stable aggregates) is accounted for by multiple variation in soil organic matter content, pH, total porosity, and bulk density.
Chemical Composition of Foliage from Fertilized Plus Douglas Fir Trees and Adjacent Unfertilized Check Trees
Authors: Beaton J. D. , Kosick R. , Speer R. C.
Published: July 2010

Shoots of the 1960, 1961, and 1962 growth were removed from two fertilized plus trees and two unfertilized adjacent check trees in April 1963. Each plus tree received 80 pounds of 16‐20‐0 ammonium phosphate sulphate fertilizer in April 1961, and 40 pounds of the same fertilizer in April 1962. The length of the shoots was measured and needle production was determined. Needles from each of the 3 years of growth were analyzed for N, P, K, Ca, Mg and S.

Fertilization increased the length of the 1962 shoots. Diameter of the shoots also appeared to be increased. Needles from the fertilized trees seemed to be larger and darker green in color. Weight of needles produced in 1962 was greatly increased by fertilization. Concentration and weight of N in needles was markedly increased by fertilization, particularly in the 1962 growth. Phosphorus concentration was slightly reduced by fertilization. However, the weight of P in the 1962 needles was increased by fertilization. The N/P ratios in all needle samples from the fertilized trees were much greater than those in the unfertilized check trees. Although K concentration was reduced in the foliage from fertilized trees, weight of K was not influenced by fertilization. Potassium percentage tended to be lowest in the oldest tissue, and highest in the youngest tissue of all trees. Concentration and weight of Ca was highest in foliage from the fertilized trees. Calcium concentration increased with age of all foliage samples. Fertilization resulted in an increase in concentration and weight of Mg. Concentration and weight of S was highest in the foliage from fertilized trees. Older needles appeared to have a higher S concentration than the younger needles.
The Influence of Low Temperature and Various Concentrations of Ammonium Nitrate on Nitrification in Acid Soils
Authors: Anderson O. E. , Boswell F. C.
Published: July 2010

Several cultivated, acid soils were limed to pH 6.0 to 6.4, treated with 100 ppm. NH4‐N as NH4NO3, and incubated for 12 weeks at low and at near‐optimum temperatures for nitrification. In sandy soils, nitrate accumulation at 42°F. was either completely suppressed or delayed for several weeks. In a clay loam incubated at 37°F. nitrates accumulated at a very slow rate throughout the 12‐weeks but at 47°F., after a 6‐week delay period, the accumulation proceeded at a rapid rate. The great influence of differing soil characteristics on nitrification is shown by the fact that nitrate accumulation in the clay loam at 37°F, was about two‐thirds of that occuring in a loamy sand at 90°F. When the amount of added NH4NO3 was increased to 200 or 400 ppm. NH4‐N, nitrate accumulation, with one exception, failed to occur at 42°F. in sandy soils and was delayed in the clay loam. Even at 90°F., nitrate accumulation in the sandy soils, but not in the clay loam, was delayed and the rate reduced.
Ion Diffusion: II. Comparison of Apparent Self and Counter Diffusion Coefficients
Authors: Phillips R. E. , Brown D. A.
Published: July 2010

The experimental distributions of Rb86 diffusing in soil materials are obtained using a quick‐freeze method. The calculation of apparent diffusion coefficients of Rb from data obtained from these distributions is presented for the following geometries: (1) self diffusion and (2) counter diffusion of Rb diffusing from soil media initially saturated with Rb into the same soil media initially saturated with H+. The distribution of Rb86 counter diffusing from kaolinite clay, montmorillonite clay, Sharkey clay soil and Dundee silt loam soil pastes into H+ saturated kaolinite, montmorillonite, Sharkey and Dundee pastes can be characterized using self diffusion theory.

The order of magnitude of apparent self diffusion coefficients is larger than those for counter diffusion in each of the four soil materials. The order of magnitude of the rate of Rb diffusion in the four soil materials is as follows: kaolinite clay > Dundee silt loam soil > Sharkey clay > montmorillonite clay. The values of the diffusion coefficients range from 3.9 × 10−7 cm.2 sec.−1 to 24.3 × 10−7 cm.2 sec.−1.

Qualitative apparent counter diffusion coefficients of Rb diffusing from soil media initially saturated with Rb into strong acid exchange‐resin discs initially saturated with H+ are also presented for qualitative comparison purposes.
Effects of Soil Temperature and Oxygen on the Amounts of Macronutrients and Micronutrients in Citrus Seedlings (Citrus sinensis var. Bessie)
Authors: Labanauskas C. K. , Stolzy L. H. , Klotz L. J. , DeWolfe T. A.
Published: July 2010

Experiments were conducted in a greenhouse during both fall and spring to study the influence of soil oxygen conditions and soil temperatures on the amounts of macro‐ and micronutrients in sweet orange seedlings (Citrus sinensis var. Bessie).

The total amounts of 11 nutrients and Na were determined in the roots and tops of citrus seedlings. Slight soil temperature differences, close to the optimum (22.5C and 27.8C) did not affect the dry weight of plants and the amounts of nutrients in the plants. However, there was a greater percentage of total K, Cl, and B found in the tops of plants grown at the higher soil temperature than at the lower.

The amounts of N, P, K, Ca, Mg, Zn, Cu, Mn, B, and Fe decreased in the citrus seedlings with decreasing soil oxygen supply to the roots. The chloride and Na content decreased in the roots and increased in the tops with decreasing soil‐oxygen supply to the roots of the seedlings.

Citrus seedlings grown during the fall months produced more dry weight of plants, and contained, in general, larger amounts of nutrients per plant, except Na and Cl, than seedlings grown during the spring months.
Phosphorus Adsorption Maximum as Measured by the Langmuir Isotherm and Its Relationship to Phosphorus Availability
Authors: Woodruff J. R. , Kamprath E. J.
Published: July 2010

The phosphorus adsorption maximum as calculated by the Langmuir isotherm was determined for a number of soils with a wide range in chemical properties. Neutralization of exchangeable aluminum markedly reduced the P adsorption maximum. The growth of millet was related to the degree of saturation of the P adsorption maximum. The soils with a large P adsorption maximum did not require as high a P saturation as those with a low adsorption maximum. Maximum yields on the limed soils were obtained when the equilibrium solution concentrations of P were greater than 0.1 × 10‐4 moles/liter of P. A much higher concentration of P was needed on the soils with a high saturation of exchangeable aluminum to give maximum yields, however, the yields were lower than on the limed soils.
A Rapid Procedure for Securing Large, Undisturbed Soil Cores
Authors: Tackett J. L. , Burnett Earl , Fryrear D. W.
Published: July 2010

A method is described for rapidly obtaining large, undisturbed soil cores ranging from 16 to 38 inches in diameter and to depths of up to 9 feet. Such cores, in some cases containing several thousand pounds of soil, may be used in‐place or moved to a controlled environment for a number of purposes; e.g., studies of transpiration, evapotranspiration, moisture flow, and others. In such cases, disturbed soil materials often are not satisfactory because of the influence of disturbing the soil on such properties as moisture transmission, moisture retention, and root distribution.
A Semimicro Technique for Studying the Oxygen Content of Gases
Authors: Sommerfeldt Theron G. , Knutson Kenneth W.
Published: July 2010

A simple, compact, portable, and relatively durable instrument has been devised whereby the oxygen content of semimicro quantities of gases can be accurately and rapidly determined. A Beckman D‐2 oxygen analyzer is connected to a vacuum pump via a 3‐way valve in a way that the system can be evacuated. The evacuation process makes it possible to analyze a gas sample of less than 20 cc where 500‐ to 600‐cc were required by the unmodified analyzer. This unit was calibrated, using gases of known oxygen content. The results were very satisfactory and well within the limits of accuracy specified by the manufacturer.
Numerical Solution of the Nonlinear Diffusion Equation for Water Flow in a Horizontal Soil Column of Finite Length
Authors: Klute A. , Whisler F. D. , Scott E. J.
Published: July 2010

The nonlinear diffusivity form of the flow equation for water in soil was solved numerically subject to the conditions: θ(0, t) = θb, t > 0; θ(x, 0) = θs, 0 < x < L; ∂θ/∂x = 0, x = L, t > 0; and D(θ) = αeβθ. In these equations θ is the volume water content, D(θ) is the diffusivity function, α and β are constants, θb and θs are the constant values of boundary and initial water content, and L is the length of the column. The solution θ(x, t) and the flux and cumulative flow across the plane x = 0 were obtained for various values of the parameter β̄ = β(θs − θb). Both inflow and outflow cases were considered, and the effect of the parameters α and β on the flow behavior is discussed.
Characterization of Aluminum Interlayers in Soil Clays
Authors: Frink C. R.
Published: July 2010

The amounts of Al, Fe, Mg, K, and Si extracted by sodium citrate from 10 soil clays containing various amounts of chloritized vermiculite are related to changes in cation‐exchange capacity (CEC), intensity of the 14A spacing and sample weight loss. Those soils containing abundant interlayers underwent the largest changes in CEC, contained the most citrate‐soluble Al and lost the most weight. Although most of the change in CEC and intensity of the 14A spacing occurred in the first 2 hours, Al was steadily extracted from sources of similar solubility for at least 6 hours. Even though the increase in CEC was well correlated with the total Al extracted, it appears that Al interlayers exist as “atolls,” and that not all citrate‐soluble Al is contained in interlayer positions. No evidence for the presence of Fe interlayers was found; rather, Fe and Mg appear to exist as contaminants in citrate‐soluble Al compounds. A weathering sequence of illite‐vermiculite‐chloritized vermiculite‐gibbsite is proposed for these acid soils. Thus, abundant Al interlayers and low CEC are among the most prominent features of highly weathered acid soils.
Ionic Relationships in Clay Suspensions and Dialyzates: I. Rubidium‐86 as a Tracer for Potassium
Authors: Franklin R. E. , Snyder G. H.
Published: July 2010

Highly significant linear correlations were found to exist between radiotracer quantities of Rb86 and the K concentrations of the dialyzate phases of clay‐water membrane equilibrium systems. The systems extended over a wide range of Ca/K saturation ratios, electrolyte concentrations, and pH values. The linear regression lines for bentonite, illite, kaolinite, and vermiculite systems had similar slopes. The actual amounts of K in the dialyzate phases were about 1.4 times the values indicated by the Rb tracer. Of the four clay minerals only the vermiculite presented problems because of specific fixation of K or Rb. Uptake of K42 by excised barley, corn, and soybean roots from bentonite systems was also significantly correlated with uptake of Rb86. It appeared that Rb86 could be used in tracer quantities to reflect relative changes in the K distribution in these systems.
Characterization of Taranakites and Ammonium Aluminum Phosphates
Authors: Frazier A. W. , Taylor A. W.
Published: July 2010

Optical, X‐ray diffraction, infrared absorption, and differential thermal analysis data are presented for the salts K3Al5H6 (PO4)8·18H2O, (NH4)3Al5H6(PO4)3·18H2O, (NH4)2AlH(PO4)2·4H2O, NH4AlPO4OH·2H2O, and NH4AlPO4OH·3H2O. Where the particle size is too small for determination of optical characteristics, a combination of X‐ray diffraction and infrared absorption methods is the most satisfactory means of identification of these compounds. Differential thermal analysis is unsuitable for the ammonium salts.
The Significance of the Rate of Organic Matter Decomposition on the Aggregation of Soil
Authors: Meredith H. L. , Kohnke H.
Published: July 2010

Laboratory studies of different types and amounts of organic materials added to a moist soil resulted in maximum release of CO2 after about 48 hours and in maximum stability of soil aggregates after about 2 weeks incubation. The experiments indicated that a fairly rapid and sustained rate of decomposition of organic residues is a necessity in the stabilization of soil aggregates. Corn stover was more effective than corn cobs—when ground to similar fineness. The benzene‐alcohol and the alkali soluble extracts from a soil that had been incubated with ground corn stalks greatly increased the aggregate stability when added to an otherwise untreated soil. The benzenealcohol soluble fraction likely reduced the rate of wetting of soil aggregates. As a consequence the dispersion effect of water was less pronounced. Water‐soluble extracts had little influence on stabilizing soil aggregates.
Variation of Soil Morphological Properties Within Miami, Celina, and Crosby Mapping Units in West‐Central Ohio
Authors: Wilding L. P. , Jones R. B. , Schafer George M.
Published: July 2010

Variation of soil morphological properties within mapping units of Miami, Celina, and Crosby soils in Ohio has been statistically summarized. Ten randomly selected profiles within each of 24 mapping delineations of these soils were sampled for this characterization. The most variable properties were horizon thickness, depth of leaching of carbonates, loess thickness, depth to mottling, pH, and class (size) of soil structure. Clay content, grade (strength) of soil structure, and soil color were least variable. The number of observations required to estimate the population mean of the above parameters within certain limits using a .95 confidence interval was computed. These soils were correctly classified with regard to great group at 96% of the 240 observations, to subgroup at 85%, to soil series at 42%, and to soil type at 39%. Parent material was mapped accurately 88% of the time; erosion, 94%; pH, 70%; solum thickness, 63%; and drainage class, 65%. Since all delineations contained 30% or more inclusions of other soils, these mapping units would be considered complex or undifferentiated units based on the present concept of a mapping unit. It is proposed that the concept of the mapping unit be modified to emphasize the dominant soil of the area rather than implying 85% mapping accuracy of a specified soil.
The Genesis of Certain Calcareous Floodplain Soils of Virginia
Authors: Mathews H. L. , Prescott G. W. , Obenshain S. S.
Published: July 2010

A study was made to determine the origin of the calcareous material found in certain floodplain soils of the limestone valleys of Virginia. The CaCO3 in these soils was derived from the highly fractured and faulted limestone underlying the area. Groundwater, high in dissolved CO2, percolated through the crushed limestone, dissolving an appreciable amount of Ca and Mg carbonate. This water issued at the surface in the form of large springs and lost some of the dissolved CO2 which resulted in a saturated solution with respect to calcium. The CaCO3 depositing alga Oocardium stratum Näg was found below the point of saturation in the streams and was thought to be of major importance in the deposition of CaCO3. In a 200‐foot section of stream channel beginning 450 feet below a spring having a rate of flow of 104 gallons/min, approximately 2.85 tons of CaCO3 were deposited annually as tufa. Algal‐deposited tufa is torn from stream channels during heavy rains and redeposited downstream by flood waters. Calcareous material occurs several miles from the source area and is a constituent of the flood plain soils along the creeks and rivers of the area.
Salt Entry into Plants
Authors: Hendricks Sterling B.
Published: July 2010

The manner of salt entry into roots is discussed. Reasons are given for considering the plasmalemma of the epidermal cells as being the rate‐limiting barrier. The dependence of uptake on aeration is considered to arise from production of adenosine triphosphate (ATP) by oxidative phosphorylation in the mitochondria. Passage of the salt at the cellular membrane, however, is considered to depend on utilization of ATP. Partial processes involve H+ exchange for cations and OH‐ exchange for anions. The eventual charge balance within the root depends on production of carboxylic acids (initially oxaloacetic) by fixation of carbon dioxide. In salt accumulation, if transport from the roots is limited, an eventual equilibrium is reached with equal efflux and influx rates. Recent work indicating that the function of K+ in plants as chiefly one of determining protein configuration is cited.
Chloride Diffusion in Clay‐Water Systems
Authors: van Schaik J. C. , Kemper W. D.
Published: July 2010

Self‐diffusion coefficients of chloride were determined in sodium‐and calcium‐saturated bentonite in steady and transient state systems. In steady state systems a decrease in diffusive flow with lower salt concentrations in the equilibrium solutions can be attributed to anion exclusion in clay‐water systems. In transient state systems the influence of the free electrolyte concentration on the porous system diffusion coefficient of chloride is practically negligible. An observed reduction by about 50% in the apparent diffusion coefficient of anions in these systems was attributed to heterogeneity of the negative adsorption due to a wide range of pore sizes.
Morphology and Genesis of Six “Red Hill” Soils in the Oregon Coast Range
Authors: Parsons R. B. , Balster C. A.
Published: July 2010

The distribution and development of six soils in the Oregon Coast Range are related to geomorphic surfaces and slope gradients on a basalt highland. The soils exhibit one or more textural discontinuities as evidenced primarily by stone lines and stone contents which decrease with profile depth.

Several soils having high base saturation and contents of Ca and Mg are related to landslides and saddles where base‐enriched groundwater moving through basalt saprolite may temporarily accumulate.
Formation of Gibbsite from Aging Hydroxy‐Aluminum Solutions
Authors: Hsu Pa Ho
Published: July 2010

Hydroxy‐aluminum solutions of NaOH/AlCl3 molar ratio = 0.3 to 2.7 and concentration of Al = 0.02m were prepared and aged for 2 years. The solutions of NaOH/AlCl3 = 1.5 and below remained unchanged during the entire period of study. Those solutions of NaOH/AlCl2 molar ratio = 1.8 to 2.7 were stable for about 6 months to 1 year, then the solutions gradually became turbid, and eventually gibbsite formed in association with a decrease in pH. When a solution of NaOH/AlCl3 = 2.7 was either diluted ten‐fold with water or dialyzed to remove the Na+ and Cl‐, the same reaction took place in 2 weeks. When NaCl was added at a concentration of 0.12m, the solution became only slightly turbid at the end of 1 year. At 0.6 and 1.2m NaCl, amorphous Al precipitates formed immediately after preparation and remained amorphous even after 2 years.

It is proposed that the formation of gibbsite from aging hydroxy‐aluminum solutions follows the same mechanism as the rapid precipitation of bayerite at NaOH/AlCl3 = 3 in an alkaline medium, the latter being discussed previously by Hsu and Bates in 1964. The difference between these two processes is the source of OH‐ for the completion of neutralization. The OH‐ added as NaOH is taken up by hydroxy‐aluminum polymers almost instantaneously, whereas the spontaneous hydrolysis of these polymers is slow, particularly in the presence of high salt concentration.
Potentiometric Titration of Acid Montmorillonite
Authors: Sawhney B. L. , Frink C. R.
Published: July 2010

Two buffer ranges representing the titration of H and Al ions are generally observed in the potentiometric and conductometric titration curves of acid montmorillonite. Recently, a third buffer range has been reported by two groups of investigators. The weak acid neutralized in the third range has not been fully characterized, however, and hence was investigated further.

Aging of acid montmorillonite prepared by passing the lay through a resin column increased both the second and third buffer ranges while it decreased the first range. In addition, the ratio of the third to the second buffer range increased continuously. Titration curves of acid clay prepared by treatment with different concentrations of HCl contained different amounts of the third range: the higher the concentration of acid, the greater was the third range. The acidic component titrated in this range was held very strongly by the clay and could not be extracted with 1n HCl or 1n NaCl.

These observations led to the conclusion that the weak acid titrated in the third buffer range of acid montmorillonite is a complex alumino‐silicate resulting from the decomposition of the clay by acid action.
Decomposition of the Iron, Aluminum, Zinc, and Copper Salts or Complexes of Some Microbial and Plant Polysaccharides in Soil
Authors: Martin J. P. , Ervin J. O. , Shepherd R. A.
Published: July 2010

Zinc, Copper, iron, and Aluminum salts or complexes of a series of bacterial and plant polysaccharides containing from 6 to 83% uronic acid units were prepared. The rate of decomposition of the metal‐polysaccharide complexes or salts and the original polysaccharide preparations was determined in Greenfield sandy loam. Some or all of the metals exerted marked effects on decomposition rate and percentage decomposition at 8 weeks of the majority of polysaccharides tested. Specific effects of the metals depended on the polysaccharide. Zinc and Al exerted very little influence on decomposition of Azotobacter chroococcum polysaccharide for example, while Cu and Fe reduced decomposition by about 50%. A much smaller percentage of Zn, on the other hand, reduced decomposition of Karaya gum from 67% to 0 in one test and to 3% in a repeat trial. The Cu‐salt of Azotobacter indicus polysaccharide was highly resistant to decomposition. After 8 weeks, 3% had decomposed compared to 29, 32, 16, and 16% for the original polysaccharide and the Al, Zn, and Fe complexes, respectively. With the exception of the Al combined with the Arthrobacter viscosus polysaccharide, all of the metals sharply reduced decomposition of A. viscosus polysaccharide and alginic acid but exerted very little effect on polysaccharides from Chromobacterium violaceum and a Bacterium sp. When added directly to the soil in concentrations equivalent to that in the metal‐A. chroococcum polysaccharide complexes (75% uronic acid), the metals exerted no effect on decomposition of Bacillus subtilis fructosan.
Examination of the Change in Soil Moisture Diffusivity During Outflow
Authors: Kunze R. J. , Peters D. B.
Published: July 2010

Experimental outflow curves were matched with theoretical curves by assuming a change in diffusivity proportional to a ratio of theoretical and experimental time values. The noted change of the diffusivity is not a function of the change in moisture content, but presumably the result of a complicated drainage sequence of soil pores.
Depth of Barrier and Water Table Fall in a Tile Drainage Model
Authors: Asseed Mohamed , Kirkham Don
Published: July 2010

A laboratory model having a transparent photographable front and containing glass beads has been used for determining, under idealized conditions, the influence of a barrier on tile drainage, in regard to both rate of fall of the water table and tile discharge. Photographs of the modeled water table and the measured discharge as it varies with time are raw experimental data, and charts of dimensionless drainage parameters have been derived therefrom. The results show that changes in depth of a shallow porous medium markedly influence drainage. A critical depth occurs when the barrier is at a depth equal to one fifth of the drain spacing; then the barrier has negligible influence on rate of fall of the water table and on drain discharge. When steady rainfall (in the form of drops of glycerol) was applied, the water table arch at equilibrium was more curved for the higher rates of rainfall. Graphs of rainfall‐intensity versus water table height were straight lines both for a position over the tiles and midway between tiles. The data reported here differ from other published data in that here a number of steady state rainfall conditions were used to establish initial conditions. Data were compared with theoretical work, and a good agreement was obtained.
A Soil Beidellite
Authors: Ross G. J. , Mortland M. M.
Published: July 2010

X‐ray diffraction analysis of the < 2 µ fraction of the main horizons of a Deer Park sand, a Podzol soil in northern Michigan, shows that montmorillonite is the dominant layer silicate in the A2 horizon of this soil. This montmorillonite appears to have weathered from illite and mica and chlorite interstratified with vermiculite and montmorillonite which are present in the underlying horizons. Chemical and X‐ray data indicate that the montmorillonite in the fine fraction (< 0.2 µ) of the A2 horizon contains some randomly interstratified mica. The Greene‐Kelly test, X‐ray powder diffraction, differential thermal, infrared, and chemical data show that the expanding component of this fine fraction is a beidellite of formula [Al1.62Fe0.18Mg0.28][Al0.45Si2.55]O10[OH]2 with exchange capacity = 0.49 M+ per half unit cell. This beidellite has a high layer charge, most of which arises from tetrahedral substitution, and shows a strong tendency to fix potassium.
The Oxidation of Elemental Sulfur in Soil
Authors: Li Paulina , Caldwell A. C.
Published: July 2010

The effects of particle size, rate of application, soil pH, temperature, inoculation, and addition of organic matter on the oxidation of elemental S in soil were studied. In general the amount of S oxidized increased with decrease in particle size. Greatest oxidation occurred with particle sizes of < 100 mesh. Oxidation reached a peak at 60 days of incubation time. The amount of S applied to the soil did not seem to affect the fraction oxidized. Little S was oxidized at 4C, some at 10C. Temperatures of 30C and 40C were more effective than 23C and lower. Inoculation accelerated the oxidation. Organic matter increased the rate of oxidation when soil samples were inoculated but did not affect the process when soil samples were not inoculated. Decrease in soil pH was highly correlated with the amount of S oxidation.
Level Pan System for Spreading and Storing Watershed Runoff
Authors: Mickelson Rome H.
Published: July 2010

Level pans were constructed in broad natural waterways to intercept runoff from contributing watersheds for storage and crop use. Stored soil moisture at seeding time in the level pans was as much in a 7‐month period over winter as that stored in unleveled fallow plots during a 19‐ to 21‐month period. Watershed runoff during the growing season provided 3 inches of moisture annually to level pans. The increased moisture supplies in the level pans permitted annual cropping with a 2‐fold or better increase in yields over unleveled dryland areas in either fallow or continuous cropping. Water‐use efficiency of grain and forage sorghums (Sorghum vulgare 'RS‐610 and ‘FS‐22’) increased with increasing moisture supplies.
Coastal Bermudagrass Response to Applications of P and K as Related to P and K Levels in the Soil
Authors: Jordan C. W. , Evans C. E. , Rouse R. D.
Published: July 2010

The response of Coastal bermudagrass (Cynodon dactylon L. Pers.) to applications of P and K as related to P and K levels in the loamy sand and sandy loam soils of the Lakeland‐Norfolk series was studied from 1959 to 1963. The annual rate of 240 lb N/acre was applied in four applications. Effect of treatment on yield, plant content of P, K, Ca, and Mg, and change in soil test values of the surface 24 inches were determined each year.

The relationships between yield and soil test P and K were described by curves calculated with a modification of the Mitscherlich equation to the form log (A − y) = log A − bc using data for initial and final years. The curves obtained showed yield response to P at soil test values < 25 ppm P and yield response to K at soil test values < 40 ppm K. Chemical analysis of samples from the surface 2 inches of soil was representative of the P and K fertility.

Plant contents above 0.16% P and 1.0% K were adequate for maximum production.

A fungal disease apparently associated with K deficiency was observed on plots receiving no K at 10 of the 18 locations in 1961 and subsequent years.
Calcium Deficiency as a Causal Agent of Ammonium Phosphate Injury to Cotton Seedlings
Authors: Adams Fred
Published: July 2010

Short‐term experiments were conducted with cotton seedlings (Gossypium hirsutum L.) on a Lakeland loamy sand at different pH levels and at different rates of (NH4)2HPO4 and NH4H2PO4. Seed was planted in a layer of untreated soil that was underlain by treated soil. The primary roots were allowed to grow into the treated soil for 48 hr. Root growth into treated soil was inhibited by several treatments, and apparent death of the primary root was effected by several other treatments. Root growth into the treated soils could not be explained in terms of soil pH, P‐rate, or individual concentrations of soil solution cations. However, if all solution cations were expressed in terms of molar activities, then a striking relationship between root growth and ratio of Ca/total‐cation or NH4/total‐cation in the soil solution became evident. Root growth was inhibited by all NH4‐phosphate treatments that resulted in Ca/total‐cation molar activity ratios in soil solution of less than about 0.15. Apparent death of root was caused by all NH4‐phosphate treatments that resulted in Ca/total‐cation molar activity ratios in soil solution of less than about 0.05. It was concluded that the injurious effect of NH4‐phosphate on cotton seedlings was a Ca deficiency in the ambient soil solution. This resulted from the precipitation of Ca phosphates and from the antagonistic action of NH+4 on Ca absorption by the root.
Soil Moisture Measurement with Ultrasonic Energy
Authors: Mack A. R. , Brach E. J.
Published: July 2010

Low energy ultrasonic waves were propagated readily at specific megacycle frequencies through samples of water and moist soil. At these frequencies, the propagated energy varied with the moisture content of the soil. Energy propagated at frequencies near 15.9 and 19.8 Mcycle/sec was sensitive to a change in moisture over a narrow range (0 to 12 g H2O/130 cm3 soil), whereas that propagated near 114 and 142 Mcycle/sec was related to moisture over a wider range (0 to 56 g H2O/130 cm3 soil). Results obtained when salts were added to the soil indicated that ultrasonic waves near 15.9 and 19.8 Mcycle/sec were affected markedly by the ionic concentration of the soil. Waves near 114 and 142 Mcycle/sec were not affected by ionic concentrations of 1 mmhos cm‐1 as measured in 1:5 soil‐water extracts. Change in texture and in organic matter content of 8 soils and 2 other materials had no significant effect on propagation at the higher frequencies (114 and 142 Mcycle/sec). Propagation of energy (114 Mcycle/sec) through moist samples changed little between 0C and about 30C, increased somewhat above 30C and decreased sharply below 0C. These higher ultrasonic frequencies appeared suitable for a nondestructive method of determining moisture content of soils.
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 3. Exchangeable Ammonium, Nitrate, and Nitrite by Extraction‐Distillation Methods
Authors: Bremner J. M. , Keeney D. R.
Published: July 2010

Methods of determining exchangeable ammonium, nitrate, and nitrite in soils are described. They involve extraction of the soil sample with 2M KCl (10 ml/g of soil) and analysis of the extract by steam‐distillation methods in which magnesium oxide is used for distillation of ammonium, ball‐milled Devarda alloy for reduction of nitrate and nitrite to ammonium, and sulfamic acid for destruction of nitrite. The distillation methods are rapid, accurate, and precise, have high specificity, and are applicable to turbid, colored, and unfiltered soil extracts. They give quantitative recovery of ammonium, nitrate, and nitrite added to soil extracts and permit nitrogen isotope‐ratio analysis of these forms of nitrogen in N15‐tracer studies of nitrogen transformations in soils.