bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties and Genesis of the Hayesville and Cecil Series of Georgia
Authors: Gibbs J. A. , Perkins H. F.
Published: July 2010

Cecil and Hayesville soils are Typic Normudults derived from acid crystalline rocks in the Piedmont Plateau and Southern Blue Ridge Soil Provinces, respectively. Morphological, chemical, and mineralogical properties were similar except for fine sand content and clay mineralogy. In general, the Hayesville series contained larger amounts of fine sand in the whole soil and more gibbsite and less kaolinite in the clay fraction than the Cecil series. Data obtained are insufficient to justify the two series as they are classified in Georgia.
Hydraulic Conductivity of Clays During Shrinkage
Authors: de Jong E.
Published: July 2010

The ratio of unsaturated to saturated hydraulic conductivity was determined for mixtures of glass beads and clay, and for a clay soil. In shrinking soils, the relative hydraulic conductivity remained fairly high over a wide range of mositure contents, while in nonshrinking soils the relative hydraulic conductivity rapidly approached zero with decreasing moisture content.
The Relationship of Soil Properties to Exchangeable and Water‐Soluble Copper and Molybdenum Status in Podzol Soils of Eastern Canada
Authors: Gupta Umesh C. , MacKay D. C.
Published: July 2010

The exchangeable and water‐soluble Cu and Mo contents were investigated from soils of the Podzol region of Eastern Canada. Average exchangeable Cu and water‐soluble Cu content varied from 1.06 to 19.30, and 0.09 to 0.46 ppm, respectively. Soils derived from Permo‐carboniferous rocks were lower in exchangeable Cu than those of other geologic origin.

In general the exchangeable Cu content was lower on sandy soils but did not vary much in other soil series. Water‐soluble Cu was not related to any of the soil properties. Exchangeable Cu did not seem to follow any continuous pattern with organic matter or pH.

Average exchangeable Mo content of different soil series ranged from traces to 0.227 ppm and was much lower in the soils derived from Permo‐carboniferous rocks. The Mo content was higher in soils with pH values > 6.0, and a significant positive correlation coefficient was observed between the two variables. Its amount was significantly higher on the fine‐textured soils than on the coarse‐textured sandy soils.
Polar Desert Soils
Authors: Tedrow J. C. F.
Published: July 2010

The northern extremeties of ice‐free land are mantled primarily with Polar Desert soils. Polar Desert soils are sparsely colonized by vascular plants and in many instances the organic component scarcely enters the soil system. Low temperature, relatively dry soil conditions, a desert pavement, mildly acid to alkaline reaction, and salt efflorescences commonly characterize the Polar Desert soils.
Effect of Bare Fallow, Barley, and Grass on Salinity of a Soil Over a Saline Water Table
Authors: Sandoval Fred M. , Benz L. C.
Published: July 2010

Considerable acreage in the semiarid to subhumid upper midwestern USA is affected by excessive salinity, which occurs mainly on nonirrigated lands with high water tables where methods for improvement are limited. In northeastern North Dakota a 4‐year study was conducted to compare effects of bare fallow, perennial grass and barley culture on salinity of land affected by a highly saline, shallow water table that ranged in depth from 0.5 to 3 m during the study period. Land use did not appreciably influence salinity of the surface 15 cm. However, by the end of the first season, 46% of the soluble salts were leached out of the 15‐ to 60‐cm depth under fallow. Salinity increased slightly under barley, and definitely increased under perennial grass. Two consecutive years of fallow removed 60% of the soluble salts in 15‐ to 60‐cm depth. Salinity reductions continued under fallow through the third year. Under grass, salinity fluctuated considerably, but generally increased, under barley, salinity fluctuated less. Quantities of ions most often moved where: Na+ > Mg2+ > Ca2+, and Cl‐ > SO42‐.
Cation‐Exchange Characteristics of Forest Floor Materials
Authors: Wells C. G. , Davey C. B.
Published: July 2010

The CEC of forest floor materials from pine, hardwood, and mixed stands was highly dependent upon the saturating cation used in the determination and somewhat less dependent upon the replacing cation. Barium saturation and Ca replacement seemed to be the best cations for CEC determination. Base titration of electrodialyzed samples indicated a 4‐min period of rapid H release followed by a decreasing rate of release. Cation‐exchange capacity of the different materials increased proportionally with pH of the saturating solution, even though the materials differed in source and composition. Buffering properties of the forest floor organic materials were strongest primarily at slightly acid to alkaline reactions. Regardless of the tree species and state of decomposition, correlation of CEC with N content of the material was highly significant. The forest floor may have a higher total CEC than several inches of underlying mineral soil.
An Evaluation of Mogilevkina's Method of Determining Fixed Ammonium in Soils
Authors: Nelson D. W. , Bremner J. M.
Published: July 2010

Studies using soils and ammonium‐saturated clay minerals showed that Mogilevkina's method of determining fixed ammonium gave much lower values than HF methods and was unsatisfactory. The heat treatment used in this method for removal of organic‐N and exchangeable ammonium‐N leads to loss of fixed ammonium, and the Kjeldahl procedure used to determine the nitrogen in the residue from this treatment fails to recover this nitrogen quantitatively.
Evaluation of the Evaporation Zone in Soil by Measurement of Heat Flux
Authors: Gardner H. R. , Hanks R. J.
Published: July 2010

Heat flux plates were employed to measure the movement of heat within a soil column during the process of water evaporation. The movement of the zone of evaporation was followed for a bare soil column with and without a surface treatment of hexadecanol. Under these conditions the evaporation zone was approximately 1 cm thick, and equal rates of evaporation were found for the check and hexadecanol treatments when the zones were at the same depth after the treated zone had been passed. Diurnal fluctuation of applied heat energy slowed the evaporation process but the evaporation zone movement was still evident.
Availability and Fractionation of Residual Phosphorus in Soils High in Aluminum and Iron
Authors: Robertson W. K. , Thompson L. G. , Hutton C. E.
Published: July 2010

The fate of applied P has been studied on two soils high in Al and Fe using the method of Chang and Jackson (2). Water soluble‐P, Ca‐P, Al‐P, and Fe‐P fractions were determined. The “occluded” and organic P were not determined but were considered to be the difference between the above forms and the total P.

Single applications of concentrated superphosphate (CSP) and rock phosphate (RP) up to 175 and 349 lb of P/acre respectively were made to Norfolk loamy fine sand, and corn (Zea mays L.) was used as an indicator crop. Annual applications of ordinary superphosphate (OSP) to the same plots using the split‐plot technique gave significant yield responses in all but 3 of the 5 years following P application. Only a small part of the increase in total P due to the initial P application could be accounted for in the Al‐P, Fe‐P and Ca‐P fractions after 8, 11 and 13 years cropping. Apparently much of the P had been converted to occluded P. This may account for the need for currently applied P.

After 2 years 220 lb of P/acre from CSP applied to Red Bay fine sandy loam raised the total P 95 lb/acre above that of a 110 lb/acre application. Of this amount 54, 28 and 5 lb/acre (92%) were in the Al‐P, Fe‐P and Ca‐P forms, respectively. An 108 lb of P/acre increase in total P due to an application of OSP 8 years before raised the Al‐P, Fe‐P and Ca‐P, 17, 15 and 3 lb/acre (32%), respectively. Assuming that CSP reacted in the soil like OSP, it was apparent that P was converted to other forms with time similar to Norfolk loamy fine sand. The formation of Fe‐P from Ca‐P in Red Bay fine sandy loam was related to total P 2 and 8 years after application.

After 2 years there was 4.1 and 1.5 times as much Al‐P and Fe‐P, respectively, in the soil following CSP than RP treatments for Red Bay fine sandy loam. Plant uptake data using P32 also showed P from CSP was more available than from RP.
Effect of Added Plant Tissue on Decomposition of Soil Organic Matter Under Different Wetting and Drying Cycles
Authors: Arsjad Sitanala , Giddens Joel
Published: July 2010

The so‐called priming effect occurred during the first 22 days when C14 labeled soybean (Glycine max) stems or leaves were added to Cecil and Bladen soils under constant moisture and under wetting and drying cycles. After 96 days the effect of added plant tissue upon native soil organic matter decomposition was significant for Cecil but not for Bladen soil Wetting and drying greatly increased soil organic matter decomposition and increased the priming effect in the Bladen soil for the first incubation period but decreased this effect in the Cecil soil.
Characterization of a Streptomyces sp. Isolated from Root Nodules of Ceanothus velutinus Dougl.
Authors: Wollum A. G. , Youngberg C. T. , Gilmour C. M.
Published: July 2010

A procedure using a 20% solution of H2O2 as the sterilizing. agent was developed which allowed the isolation of a Streptomyces sp. from the root nodules of C. velutinus. This was repeated 17 times and a total of 136 similar streptomyces sp. were isolated from the nodules of this nonleguminous, nitrogen‐fixing plant. Further characterization by standard bacteriological procedures suggested that the isolates belonged to a single species, which did not correspond to any previously recognized Streptomyces sp The inoculation of sterilized, germinated seeds with some of the isolates showed that they were capable of initiating the infection of root hairs on C. velutinus. Infection and nodulation of C. velutinus occurs in at least three distinct phases. At first there is a swelling at the tip of the root hair, which is followed by a marked swelling. As infection continues the root hair becomes swollen to its base. Shortly after this point has been reached the final phase of the process is recognized as the formation of visible nodules on the root surface. In the presence of some isolates and a sterile nodule extract, the infection process has been observed to the point where the entire root hair has become swollen. Without the sterile extract the infection was not as complete and progressed much slower. When the isolate is omitted and the seedling inoculated with the sterile nodule extract, a slight swelling at the root hair tip occurs. Despite the similarity of the isolates, infective ability of the isolates which appears to be a unique feature of the endophyte, no species name should be proposed until the demonstration of nodule formation with the isolate. Also it was suggested that some predisposing agent(s) may be required for the rapid initiation of the infection process in C. velutinus seedlings.
Mechanisms for the Movement of Mn, Fe, B, Cu, Zn, Al and Sr from One Soil to the Surface of Soybean Roots (Glycine max)
Authors: Oliver S. , Barber S. A.
Published: July 2010

The role of root interception, mass‐flow and diffusion in supplying ions to soybeans growing in a leached subsoil was investigated. Root interception was the main mechanism for the supply of Cu, Al and Sr to the soybean roots. Mass‐flow was the most important for B and diffusion was the most important for Mn, Fe and Zn.

The most significant mechanisms will likely vary with the crop grown, climate and soil.
A Culturing Unit to Evaluate Sodic Influence on Calcium Nutrition of Alfalfa
Authors: Nightingale H. I. , Smith R. L.
Published: July 2010

A culturing unit was constructed whereby the influence of exchangeabe sodium on the growth and mineral uptake of established alfalfa (Medicago sativa) could be determined. Two compartments, separated by a membrane through which roots could penetrate, were placed one above another. The top compartment contained a calcareous nonsodic soil to which Ca45CO3 was added. The lower compartment contained complete nutrient solution.

Following the establishment of the plants in the nonsodic soil and complete nutrient solution, four levels of exchangeable Na percentage, 0.9, 14.9, 35.4, and 54.9, were established by adding solutions of Na2CO3 to the soil. The yield and Ca content of leaves was reduced by the sodic influence even though sufficient Ca was available to the plant through the nutrient solution. This decreased Ca uptake was compensated for by greater uptake of Mg.
Comparison of Fragipan and Bisequal Profiles of the Gulf Coastal Plain with Soils of Southern Loess Belt
Authors: Vanderford H. B. , Shaffer M. E.
Published: July 2010

Bisequal profiles with fragipans have been studied in the Southern Loess Belt by several research workers. The purpose of this paper is to compare morphological, physical and chemical properties of silty soils that developed in the Gulf Coastal Plain with features of similar soils in the Loess Belt. Bisequal profiles with fragipans are common in the Coastal Plain which are similar in morphology to bisequal soils that are found in the Southern Loess Belt. The bisequal expression varies with drainage with the maximum development in somewhat poorly drained profiles. The leached A′2 horizon above the firm fragipan attains a thickness of 3 or 4 inches in some soils, and seems to grow upward into the B2 horizon and downward by tongues and cleavage streaks into the fragipan. It appears to be the most highly weathered horizon in the profile and clay particles migrate from this zone into the fragipan by way of the gray streaks. As this process continues a cambic layer forms above the A′2 horizon in the moderately well and somewhat poorly drained profiles. The genesis of these soils in the Gulf Coastal Plain appears to be similar to the genesis of bisequal profiles of the Loess Belt. Knowledge of the genesis and nature of the bisequal profiles will aid in classifying these soils in the new system of classification.
The Persistence of Decaying Wood in the Humus Layers of Northern Forests
Authors: McFee W. W. , Stone E. L.
Published: July 2010

The amount, composition, and persistence of decaying wood in humus layers was examined in yellow birch (Betula alleghaniensis Britton)‐red spruce (Picea rubens Sarg.) stands in the Adirondack Region of New York. The wood is initially attacked by brown rot fungi, but thereafter decomposes very slowly and may persist in the humus layer for a century or more. Separable wood residues weighed as much as 41,800 lb/acre and composed 14 to 30% of the forest floor. These residues were significantly lower in N and P content than the surrounding humus.
Simultaneous Determination of Surface Area and Cation‐Exchange Capacity
Authors: Bower C. A. , Hatcher J. T.
Published: July 2010

In previous work it was found that Cl repulsion by arid‐zone soi's from a solution having a high and uniform concentration of Cl is closely related to surface area as measured by ethylene glycol retention. Based on this information, a measurement of Cl repulsion has been incorporated into the NaOAc method for determining cation‐exchange capacity. As a result, values for surface area, as well as cation‐exchange capacity, can be obtained with but little additional analytical work, except for soils high in kaolinite and sesquioxides.
Osmotic Efficiency Coefficients Across Compacted Clays
Authors: Kemper W. D. , Rollins J. B.
Published: July 2010

Movement of solution through clays in response to salt concentration differences and in response to hydraulic pressure differences was measured. Rate of movement of solution in response to an “osmotic pressure” difference was divided by the rate of movement in response to an energywise equal hydraulic pressure difference to obtain osmotic efficiency coefficients. These osmotic efficiency coefficients are increased by saturating the clay with monovalent rather than divalent cations, using divalent rather than monovalent anions, decreasing the water content of the clay plug and by decreasing the average concentration of the outside solution. Effects of these factors on the osmotic efficiency are predicted by diffuse layer theory (negative adsorption of salt) and hydrodynamic considerations.
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 4. Exchangeable Ammonium, Nitrate, and Nitrite by Direct‐Distillation Methods
Authors: Keeney D. R. , Bremner J. M.
Published: July 2010

Methods of determining exchangeable ammonium, nitrate, and nitrite in soils which do not require extraction of the soil sample are described. The soil sample is treated with 2M KCl (5 ml/g of soil) and analyzed directly by steam‐distillation methods involving use of magnesium oxide for liberation of ammonium, ball‐milled Devarda alloy for reduction of nitrate and nitrite to ammonium, and sulfamic acid for destruction of nitrite. The methods are rapid, specific, and precise, and they permit nitrogen isotope‐ratio analysis of exchangeable ammonium, nitrate, and nitrite in N15‐tracer studies of nitrogen transformations in soils. Results of soil analyses by these direct‐distillation methods are practically identical to those obtained by extraction‐distillation methods.
Quenching the High Phosphorus Fixation of Hawaiian Latosols
Authors: Younge O. R. , Plucknett D. L.
Published: July 2010

Hawaii aluminous‐ferruginous latosols are severely deficient in total and available phosphorus and have very high phosphorus fixation capacities. This severely limits croup production. Results of 6‐year field experimentation indicate that the problem of phosphorus fixation and low yields can be overcome by a heavy initial phosphorus treatment which quenches the fixation complex, and thus diverts the extra phosphorus to maximum yield production. Additional phosphorus must be added every few years to replace depletion by crop removal, erosion and slow residual fixation. Long‐term yields indicate the costs of reclamation may be readily amortized over a 10‐ to 20‐year period.
Colorimetric Determination of Iron of Mixed Valency by Orthophenanthroline
Authors: Murti G. S. R. Krishna , Volk V. V. , Jackson M. L.
Published: July 2010

A colorimetric method for the determination of Fe in a mixed Fe3+ and Fe2+ valency system has been proposed. Complete reduction of Fe3+ to Fe2+, which was essential for the formation of a stable colored complex with orthophenanthroline, was obtained when the iron solution, buffered at pH 3.5 with sodium acetate, was heated for 1 hr at 65C with 5% hydroxylamine hydrochloride. This reduction procedure was found to be suitable even for solutions at a higher pH where iron was present either as Fe3+ or as a hydroxylated complex. The organe color complex was found to be stable at pH values 2 to 9 for at least 20 hr and no interference of citrate ion was observed in the stability or the formation of the color.
Ionic Balance and Growth of Sixteen Plant Species
Authors: Noggle J. C.
Published: July 2010

The total concentration of inorganic cations (K+, Na+, Ca2+, Mg2+) exceeds the total concentration of inorganic anions (NO3‐, H2PO4‐, SO42‐, Cl‐) in most plant tissue, and the difference between the two is an estimate of the organic anion concentration. Previous investigations have shown that vegetative growth of barley with high fertilization rates was regulated to some extent by the organic anion concentration. In this study, 16 plant species were grown in the greenhouse to test the consistency of this relation with different ion accumulation patterns. The inorganic anion content of the plant tissue was varied by applying either SO42‐ or Cl‐ to the soil. All Cl‐treated plants had a higher inorganic anion concentration than the SO4‐treated plants. The organic anion concentration in 10 of the plant species was lower in the Cl‐treated plants. The lower yield of each plant species was associated with the plants that had the higher total inorganic anion concentration. The results of this study, with one possible exception, are consistent with the concept that reducing the organic anion concentration in plants reduces growth.
Cation‐Exchange Capacity as a Function of Organic Matter, Total Clay, and Various Clay Fractions in a Soil Toposequence
Authors: Wilding L. P. , Rutledge E. M.
Published: July 2010

Soil cation‐exchange capacity (CEC) as determined for A and B horizons of Miami, Celina, Crosby, and Brookston soils was statistically partitioned using multiple linear regression analyses into the following sets of components: [1] organic matter (OM) and total clay; and [2] OM, 2‐0.2µ, and <0.2µ clay. Coefficients of multiple correlation (R) for independent variables used in regression components [2] are of larger magnitude but not significantly different from components [1]. R values for components [1] range from .76 to .87 and for components [2] from .78 to .92. Organic matter contributes most to the CEC in A horizons whereas <0.2µ clay contributes greatest to the CEC of B horizons for soils of this toposequence. With one exception, 2–0.2µ clay is not significantly correlated with CEC in either A or B horizons. The average CEC of OM for Brookston A horizons is lower than for other toposequence members (154 vs. ca. 200 meq/100 g), whereas for B horizons it is considerably greater (361 vs. ca. 290 meq/100 g). The average CEC of fine clay in B horizons progressively increases with decrease in drainage class, varying from about 70 meq/100 g in Miami to 121 meq/100 g in Brookston.
Forces Involved in Ion Fixation by Vermiculite
Authors: Kittrick J. A.
Published: July 2010

The temperature at which vermiculite loses or gains an interlayer of water molecules was compared for a number of interlayer ion saturations. Results indicate the difference between contracting and expanding forces in vermiculite to be dependent upon interlayer ion charge, distance, and hydration energy. Important interlayer forces therefore must be electrostatic attraction between the negatively charged layers and the positive interlayer ions, and expansion due to ion hydration. Basically, ion fixation appears to occur when electrostatic forces of attraction exceed those of hydration
Reactions of Selenite‐Selenium Added to Soils That Produce Low‐Selenium Forages
Authors: Cary Earle E. , Wieczorek George A. , Allaway W. H.
Published: July 2010

Alfalfa (Medicago sativa L.) absorbed Se in concentrations potentially toxic to livestock from four of seven soils treated with radioactively labeled Se at a 2.5‐ppm rate as a selenized concentrated superphosphate. When the Se rate was 0.5 ppm, only the first few crops from one soil contained toxic amounts. Subsequent alfalfa crops from all seven soils receiving 0.5 ppm and six of seven soils receiving 2.5 ppm contained nearly constant, nontoxic levels of Se that would protect animals from Seresponsive diseases.

After 1 year of cropping soils in pots in a greenhouse, up to 40% of the residual Se could be removed by isotopic exchange with selenite. Further fractionation indicated that organic Se compounds and elemental Se or selenides are also probably present in the residual Se.
Analysis of Gamma‐Ray Spectra From Soils and Plants: I. Computer Program With Correction for Gain‐Shift and Sample Bulk Density
Authors: Elfield Mark , Franklin R. E.
Published: July 2010

A computer program and counting techniques used in analyzing complex gamma spectra were developed. The program computes a standard spectrum for each radioisotope based on the bulk density of the sample and then corrects for differences in the energy equation of reference and sample spectra. A solution is then obtained by the method of least‐squares.

In addition to a numerical solution, the program provides logarithmic plots of the unknown spectrum, the solution, and the individual components. The approximate execution time is 10 to 15 seconds on an IBM 7094 computer. The program presently has a capacity of 16 standard spectra (512 channels each). This program has been applied successfully to the analysis of complex gamma spectra obtained from soils and plants.
The Measurement of Water Loss by Mesquite (Prosopis glandulosa var. glandulosa Torr.) Using the Thermoelectric Method
Authors: Wendt C. W. , Runkles J. R. , Haas R. H.
Published: July 2010

The quantitative aspects of the thermoelectric method were investigated in a controlled environment chamber using mesquite (Prosopis glandulosa var. glandulosa Torr.). A high degree of correlation for trees less than 10 mm in diameter (r = 0.97) was obtained between water transpired and the product of the cross‐sectional area of the stem and the relative sap velocity. As the size of trees increased the correlation decreased due to variations in relative sap velocities around the circumference of larger trees. Although the correlation coefficient was high for trees less than 10 mm in diameter, the coefficient of variation was 15.6% which was probably due to the variation in the moisture content of the plants.
Soil Atmosphere as Influenced by Temperature and Moisture
Authors: Yamaguchi M. , Flocker W. J. , Howard F. D.
Published: July 2010

Composition of the atmosphere of Yolo sandy loam soil columns was determined at different depths and different soil moisture conditions. After saturation with water, soil columns were placed in 30, 25, 20, 15, or 10C constant temperature rooms and moisture was allowed to evaporate from the soil surface. Soil moisture content was determined with a gamma‐ray densitometer; CO2, O2, and N2 concentrations were determined by gas chromatography. After 14 days at 30C, moisture tension at the 65 cm depth was 0.1 bar and the soil atmosphere contained 17% CO2 and 4% O2. At the 35‐cm depth, the moisture was 0.3 bar and the CO2 and O2 concentrations were 7% and 14%, respectively. At the 5‐cm depth the CO2 did not rise over 1.5%. At lower temperatures the CO2 did not rise over 1.5%. At lower temperatures the CO2 concentrations were less and the maximum was reached more slowly. However, the N2 concentration increased to almost 90%. At each temperature and all depths, rapid changes occurred in the concentration of gases when the soil moisture tension reached 0.10 to 0.15 bar.
Reactions of Ammonium Polyphosphates with Soil Minerals
Authors: Philen Otis D. , Lehr James R.
Published: July 2010

When suspended in solutions of ammonium pyro‐ or tripoly‐phosphates at room temperature, calcium and magnesium carbonates reacted rapidly and clay minerals and hydrous oxides of iron and aluminum reacted slowly. The precipitated solid products of the reactions included calcium and magnesium ammonium pyro‐ and tripolyphosphates and iron and aluminum ammonium pyrophosphates but no tripolyphosphates; no solid orthophosphates were formed. The condensed phosphates were much less reactive with the soil minerals than are orthophosphates.
Interaction of Ammonium and Potassium in a Potassium‐Fixing Soil
Authors: Bartlett R. J. , Simpson T. J.
Published: July 2010

Different levels of NH4 and K were supplied to a K‐fixing soil (Buxton silt loam) containing the nitrification inhibitor 2‐chloro‐6‐(trichloromethyl) pyridine. Maize (Zea mays L.) seedlings were grown in the soil under controlled conditions.

When K was equilibrated with this soil first, adidtion of NH4 had almost no effect on the availability of K, as indicated by extraction with NaOAc or by uptake of maize seedlings.

Equilibration of the soil with NH4, before the addition of K, increased the amount of K extracted, increased the percentage of K in the p ants, and increased the yields of seedlings.

Addition of NH4 at the same time as K was at least as effective as its addition before K in increasing yields as we 1 as amount of K taken up by the plants or extracted chemically from the soil.
Seepage of Steady Rainfall through Soil into Ditches of Unequal Water Level Heights
Authors: Powers W. L. , Kirkham Don , Snowden G.
Published: July 2010

A theoretical solution and numerical results for the seepage of steady rainfall into soil laying above an impermeable layer and drained by ditches of unequal water level heights is obtained for the ditches just reaching or penetrating into the impermeable layer. This is done by using a finite series of orthonormal functions generated from products of trigonometric and hyperbolic functions. The theoretical solution gives the potential function and stream function for a range of water level heights, ditch spacings, and a range of ratios R/K of rainfall rate R to hydraulic conductivity K. If R/K is increased from 0 to 0.05, for 10‐m spacing of ditches and for 1 ditch having water maintained 1 m above the barrier and the other ditch 1.5 m; then the maximum water table height in the soil will increase from 1.50 m to 1.82 m. Also, as R/K increases, the position of the maximum water table height will approach a position midway between the ditches. Flow nets and other results computed for a number of geometries from the theory bring out additional information.
Determination of Iron with Thiocyanate
Authors: Hsu Pa Ho
Published: July 2010

The effects of acidity and concentration of thiocyanate on the intensity and stability of the iron‐thiocyanate color solution were studied in detail, and a procedure was proposed. In the proposed procedure, a combination of 3 ml of 6N HCl and 10 ml of 20% KSCN is recommended. In the presence of this amount of KSCN, the color intensity was constant while the amount of HCl varied from 5 to 30 meq. Hydroxy‐iron polymers in the sample solution can be decomposed by heating the aliquot in the presence of acid prior to the addition of KSCN. By adding H2O2 at the end of the procedure, it is possible to confine the reading time within a short interval and thus overcome rapid color fading.
The Effect of Water Content on Axial Strain in a Loam Soil under Tension and Compression
Authors: Farrell D. A. , Greacen E. L. , Larson W. E.
Published: July 2010

A method is described for measuring axial strain in a remolded loam soil under unconfined axial loading in both compression and tension. Using this method the stress‐strain relationships for the loam soil were determined for soil‐water contents ranging from 2% to 12% by weight.

The maximum tensile stress in a soil beam stressed to failure in a modulus of rupture test was computed from the measured stress‐strain relationships. This computed fiber stress was approximately 10% greater than the measured tensile strength.

The strain energy required to rupture this soil in axial tension, taken as the area under the stress‐strain curve, was shown to increase by only 20% for a sixfold increase in tensile strength and to be almost proportionately related to the energy required to produce a fixed degree of soil breakup in a drop‐shatter test.
Hydraulic Properties of Disturbed Soil Materials Affected by Porosity
Authors: Laliberte G. E. , Brooks R. H.
Published: July 2010

Recently some hydraulic properties of porous materials have been described for use in constructing valid physical models that are easily measured and practically significant. These properties have been used to express similitude requirements for drainage of initially saturated soils.

This paper describes how soil packing effects the hydraulic properties of three soil materials. Soil packing as measured by bulk density and porosity is related to bubbling pressure, poresize distribution index and permeability. With a light hydrocarbon oil as the wetting fluid the pore‐size distribution index was changed only slightly over a wide range of porosities. Permeability and bubbling pressure, on the other hand, were changed severalfold over the same range of porosities.

For modeling purposes, one requirement for similitude between model and prototype is identical values of pore‐size distribution index. Evidently, bubbling pressure may be adjusted to suit the size of the model by changing the packing density without appreciably changing the pore‐size distribution index.
Tillage Pan Characterization of Selected Coastal Plain Soils
Authors: Kashirad A. , Fiskell J. G. A. , Carlisle V. W. , Hutton C. E.
Published: July 2010

Tillage pan characteristics in Lakeland, Norfolk, Red Bay and Orangeburg soil series were studied at 20 paired locations of cultivated and virgin areas. Pits for sampling were dug following periods of heavy rainfall. Tillage pans were identified by pocket penetrometer readings of the compaction. Sampling depths from adjacent virgin sites corresponded to those in the cultivated sites. These pans showed consistently higher compaction, bulk density, and less pore space than the soil above or below the pan or the corresponding adjacent virgin soils. Sand, silt, and clay contents were not significantly different between virgin and cultivated samples.

Sequential extraction with hydrogen peroxide, dithionite‐citrate, and 0.5N NaOH was made of the cultivated and virgin soils for depths above, in, and below the pan. Dithionite‐citrate extraction for free Fe removed less Al and Si than the subsequent extraction with 0.5N NaOH. Accumulations of Fe, Al, and Si were significantly greater in the pan but these were not consistent for each soil series. Organic matter probably helped to filter and encourage accumulations of some compounds in the pan which might be important in cementation properties. Roots either failed to penetrate these tillage pans or were constricted to much poorer lateral growth compared to roots above or below the pan.
Soil‐Water Properties Computed from Transient Flow Data
Authors: Weeks L. V. , Richards S. J.
Published: July 2010

A method is given for calculating water conductivity (K) of unsaturated soil by the use of data obtained during transient changes of moisture content (θ) and suction head (h) along a horizontal soil column. A soil moisture characteristic curve was obtained from the data. Absolute values of the slopes of the latter curve, the differential water capacity (C), pertaining to the experimental values of h were then used to calculate soilwater diffusivity (D) from the equation, D = K/C. The experimental procedure does not involve boundary conditions that, in some procedures, are difficult to evaluate, nor are steady‐state and equilibrium‐flow conditions required. Data for most soils was obtained in from 8 to 12 days. A program was written in Fortran IV language for use with the IBM 7040 Data Processing System. The solution of the problem was reduced to a routine that saves several hours of hand calculations.

Values of K, C, and D for field cores and laboratory compacted soil columns were measured over the range of 50 ≤ h ≤ 750 cm of water. Relative error values between measured values of K and those calculated from the equation K = ch‐d were less than 50% in 83% of 288 measurements. Relative error values between measured values of D and those calculated from the equation D = α exp (βθ) were less than 50% in 74% of the 288 measurements. The constants, c, d, α, and β are empirical for a given soil. Water conductivity values were shown to be independent of hydraulic gradients over a wide range of gradient values.
Mineralogical and Chemical Characteristics of Soils in Loess Overlying Shale in Northwestern Illinois
Authors: Jones Robert L. , Ray B. W. , Fehrenbacher J. B. , Beavers A. H.
Published: July 2010

Eleroy and Derinda soils (Typic Hapludalfs) and Keltner and Schapville soils (Typic Argiudolls) were studied. Weathering of silt‐size minerals is not advanced in these relatively youthful soils. Iron is the most sensitive indicator of weathering, being particularly labile in the Hapludalf profiles. Iron weathers from silt‐size minerals and is localized in concretions and in the clay fraction. Clay‐mineral weathering involves formation of chloritized vermiculite and montmorillonite from illite and montmorillonite precursors. The stage of weathering of these soils approximates that in Clinton, Fayette (Hapludalfs), and Tama (Argiudoll) soils that occur along the Mississippi River. Soil test values for K and P and amounts of exchangeable K and total P are high. Productivity is related more to depth of underlying shale and attendant physical effects than to nutrient status.
Soil Survey Refinements for Predicting Black Oak Site Quality in Southeastern Ohio
Authors: Carmean Willard H.
Published: July 2010

Soil‐site studies in southeastern Ohio reveal the need for soil survey refinements for accurate classification of black oak (Quercus velutina Lam.) site quality. These studies also have identified the specific soil and topographic features closely related to oak‐site quality. This information is used as a basis for designing mapping units for more accurate estimation of oak‐site quality. Existing soil series are combined into two “woodland suitability groups,” each of which includes soils similar in average site quality and soil morphology. Then these two groups are phased, using the specific soil and topographic features known to be closely related to oak‐site quality. A large number of multiple regression equations are available for calculating the required phases, but equations based only on topographic features explain more than 75% of the height variation. They are the most practical for forest‐site quality phasing because they can be easily applied by using aerial photographs and topographic maps. The exceptional precision of the topographic equations is due to correlations between topography and soil features significantly related to oak site quality. Such close correlations have long been recognized by soil surveyors as a basis for delineating boundaries of soil mapping units. Hence, using these correlations as a basis for phasing for site estimation is a logical extension of present survey practices.
The Adsorption of Atrazine and Atratone by Anion‐ and Cation‐Exchange Resins
Authors: Turner M. A. , Adams R. S.
Published: July 2010

The adsorption of two herbicides, atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐s‐triazine), and atratone (2‐methoxy‐4‐ethylamino‐6‐isopropylamino‐s‐triazine), was studied using a cation‐ and an anion‐exchange resin saturated with selected ion species. The amount of herbicide adsorbed was found to vary with the herbicide and with the ion present at the exchange site. Both atrazine and atratone were adsorbed by the cation‐ and anion‐exchange resins, but atratone exhibited the more pronounced affinity for the cation saturated resins.

The data in this study suggested the possibility of complex formation between the herbicide molecule and certain cations present at the exchange site of the resin as a mechanism for adsorption. The further use of resins for evaluating herbicide adsorption mechanisms is advocated.
Relation between Landform Parameters and Soil Properties
Authors: Walker P. H. , Hall G. F. , Protz R.
Published: July 2010

Landform parameters of slope gradient, slope length direction, curvature, distance from the hillslope summit, and elevation relative to the summit were recorded with soil profile observations across small loess and drift landscapes in Iowa. Simple regression and correlation analyses were used to examine the relationship between each soil property and the parameters and also the relationships among parameters. The geomorphic parameters were then fitted to soil data in different combinations in multiple regression. Generally, elevation and slope were most strongly related to the soil properties measured. Slope length direction was also an important parameter for A horizon thickness and subsoil mottle features. When two of the sites were subdivided into convex and concave areas, significant regressions were again obtained. Nevertheless, considerable soil variation remained unaccounted for. This may result from the relict nature of some of the subsoil features, or in the case of A horizons, from faunal activity.
Soil Reflectance, Temperature, and Fallow Water Storage on Exposed Subsoils of a Brown Soil
Authors: Black A. L. , Greb B. W.
Published: July 2010

The topsoil of a Weld soil on an 0.84% slope was removed, giving an increasing depth of subsoil exposure ranging from 0 to 38.1 cm over a horizontal distance of 45.7 m. Five subranges of subsoil exposure—0 to 7.6, 7.6 to 15.2, 15.2 to 22.8, 22.8 to 30.4, and 30.4 to 38.1 cm—were formed with each subrange corresponding to a horizontal distance of 9.14 m. The exposed surface 5 cm of these soil removal treatments differed in texture, structure, reflectance, clod bulk density, aggregate stability, and wind‐erodible soil fraction.

Over a 5‐year period, mean fallow efficiency for all five soil removal treatments ranged from 25.6 to 38.5%. Reflectance of the exposed surface 5 cm of soil of each soil removal treatment varied considerably among treatments. Mean soil temperatures in fallow were negatively correlated with visual efficiency (P = .05) which was used as an indirect value of soil reflectance. Average soil water gained in fallow was negatively correlated (P = .05) with the mean fallow soil temperature measured at a depth of 7.6 cm. The negative correlation between soil water gained and mean soil temperature was significant (P = .01) in a dry year (1960) and nonsignificant (P = .05) in a year of above‐average precipitation (1957). A positive correlation was obtained between soil water gained during fallow and visual efficiency (P = .10).

Soil water storage in fallow and depth to seedbed water were influenced by soil texture and aggregation in some years. No significant relationship was found between soil water storage at the end of fallow and subsequent crop production because of interactions involving soil temperatures and fertility levels.
Analysis of Steady‐State Evapotranspiration from a Soil Column
Authors: Whisler F. D. , Klute A. , Millington R. J.
Published: July 2010

Numerical analysis is applied to the steady‐state flow equation for evapotranspiration from a vertical soil column. The water uptake by the plant roots is incorporated into the flow equation as a (negative) source term. The evapotranspiration rate and its partitioning between plant transpiration and soil evaporation are specified as the top boundary condition. The lower boundary condition is a water table. The results of the analysis for a Pachappa sandy loam give pressure head, water content, source strength and soil water flux profiles. This study has (i) demonstrated that solutions to the flow equation with a source term can be obtained by numerical means, (ii) shown something of the theoretical influence of the parameters in the source term model on the flow in the soil, (iii) qualitatively indicated a transfer of water from wet soil via the root system, and (iv) indicated that the source term has little effect on the pressure head profile unless the evapotranspiration rate is about the same order of magnitude as the theoretical limiting value.
Adsorption of Organic Herbicides by Montmorillonite: Role of pH and Chemical Character of Adsorbate
Authors: Bailey G. W. , White J. L. , Rothberg T.
Published: July 2010

Samples of well‐characterized 1‐0.2µ montmorillonite clay adjusted to two pH values, pH 3.35 and 6.80, were reacted with members of such herbicide families as s‐triazines, substituted ureas, phenylcarbamates, aniline, anilides, phenylalkanoic acids, benzoic acids, and picolinic acids.

Graphical methods were used to plot adsorption isotherms and to determine conformity to the Freundlich or Langmuir equations. Calculations were made to determine: (i) the percent cation exchange capacity satisfied at the maximum amount adsorbed; (ii) the percent surface coverage at the maximum amount adsorbed; and (iii) the partial molar‐free energy for each concentration level; also determined graphically was the Freundlich “K” and “1/n” value.

Conformity to the Freundlich adsorption equation was found for all organic compounds studied for both the H‐clay and the Na‐clay systems with two possible exceptions: the phenoxyacetic acid‐H‐clay system and the substituted urea‐Na‐Clay systems. Conformity to the Langmuir adsorption equation was not found for any family or group studied on either H‐ or the Na‐saturated clay.

Regardless of chemical character, adsorption occurred to the greatest extent on the highly acid H‐montmorillonite compared to the near neutral Na‐montmorillonite.

Within a family or within an analog series basic in chemical character, the magnitude of adsorption is related to and governed by the degree of water solubility. The major factor governing the magnitude of adsorption of different basic chemical families is the dissociation constant of the adsorbate.

The magnitude of adsorption of organic compounds with widely different chemical character is governed by the degree of water solubility, the dissociation constant of the adsorbate, and the pH of the clay system.

The adsorption of basic organic compounds by the montmorillonite type clay system appears to be dependent upon surface acidity and not upon the pH of the suspension while the converse appears to hold true for the adsorption of acidic type compounds.

The surface acidity of montmorillonite appears to be 3–4 pH units lower than the suspension pH.

Mechanisms for the adsorption of basic and acidic organic compounds are discussed.
Moisture Characteristics of Pennsylvania Soils: I. Moisture Retention as Related to Texture
Authors: Petersen G. W. , Cunningham R. L. , Matelski R. P.
Published: July 2010

Soil moisture retentions are associated with similar soil properties within each textural class of the USDA Textural Classification and family grouping of the New Classification System. Multiple regression analyses showed bulk density most strongly associated with ⅓ atm moisture (core samples) and clay content with 15 atm moisture (<2 mm sieved samples). Organic carbon was also associated with 15 atm moisture but not with ⅓ atm moisture. Available moisture, as determined by the difference between ⅓ atm and 15 atm moisture, was negatively correlated with sand and clay and positively correlated with silt content. Available moisture was also highly correlated with ⅓ atm moisture whereas 15 atm moisture showed either no correlation or a negative correlation.

Scatter diagrams, with corresponding quadratic equations for the line of best fit, allow determinations of ⅓‐atm and 15‐atm moisture contents from known clay percentages. Prediction equations, for estimating available moisture from predetermined soil properties, are given for each textural class, with the exception of sand and sandy clay, and for each textural class of family grouping in the New Classification System.
The Variability of Forest Soils of the Georgia Blue Ridge Mountains
Authors: Ike Albert F. , Clutter Jerome L.
Published: July 2010

Data collected from 123 forested plots in the Blue Ridge Mountains of northeast Georgia were used to (i) evaluate sample stratification criteria, (ii) estimate the variability of physical and chemical properties of the soil, and (iii) examine the efficiency of sampling schemes.

Sample stratification seemed justified on the basis of soil series, but not on the basis of soil type. For similar soils, maximum efficiency in estimating means of soil series is obtained with one or two pits per plot. The number of plots (pedons) required for adequate precision is greater than the number customarily sampled for soil series characterization studies.

Sampling to estimate plot mean values in soil‐site studies involves consideration of the variances of several properties to be estimated from one soil sample. The use of two to four pits (profiles) per plot in similar soils would seem to be adequate for most but not all commonly measured soil properties.