bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of Eolian Influenced Soils in Connecticut: I. Physical Properties
Authors: Ritchie A. , Colby W. G. , Swanson C. L. W. , Tamura T.
Published: July 2010

Field and laboratory studies were made on soils strongly influenced by loess in the Central Lowland of Connecticut. Laboratory samples were obtained from 10 profiles located on a grid sampling system in an area east of the Connecticut River. Depth of the loess mantle had an important influence on the particle size composition of the profiles. The greater amounts of coarse particles in the shallower profiles are believed to be due to mixing with the underlying unconformable materials, probably through frost action and tree throw. An increase in coarse particles from the underlying material in the profile results in reductions in water‐holding capacity, capillary pore volume and penetrability, and increases in bulk density and non‐capillary pore volume, but with only a small change in permeability.
A Portable Rainfall‐Simulator Infiltrometer and Physical Measurements of Soil in Place
Authors: Adams John E. , Kirkham Don , Nielsen Donald R.
Published: July 2010

A portable rainfall‐simulator and infiltration cylinder are described for applying artificial rainfall to soil in place for making infiltration, runoff, and soil erosion measurements. Raindrops are formed by glass capillary tubes protruding through the base of the water supply tank. Each tube has chromel wire suspended in the capillary to reduce the rate of flow. The rainfall is delivered over a circular area 5 ¾ inches in diameter delimited laterally by a cylinder 6 inches long, driven vertically into and flush with the soil surface. The soil surface area is small and replications are easy to obtain. Air permeability measurements may be made before and after rainfall application. The equipment can be carried, set up, and operated conveniently by one man and offers a fast, economical means of evaluating the soil factor in runoff and soil erosion problems. Field data, obtained on the Edina silt loam after 30 minutes of artificial rainfall, showed that the infiltration rate for corn in a corn‐oat‐meadow rotation (0.70 in./hr.) was nearly twice as great as for continuous corn (0.36 in./hr.) Wash erosion, or sediment in suspension, reached a maximum value for both systems between 5 and 10 minutes after the start of rainfall. During the next 5 minutes, wash erosion decreased rapidly although runoff continued to increase.
Swelling Pressure of Montmorillonite
Authors: Warkentin B. P. , Bolt G. H. , Miller R. D.
Published: July 2010

A montmorillonite suspension was placed in a miniature compression chamber bounded on one side by a cellulose membrane supported by a water saturated porous Alundum disk, and on the other by a rubber film. Changing the ambient pressure on the film caused water to move across the membrane until the swelling pressure of the suspension equalled the applied pressure.

Existing theory, based upon the Gouy‐Chapman description of the diffuse double layer and upon its anticipated osmotic activity, was used to predict swelling pressures for different suspensions.

During initial compression, measured swelling pressures of both Na‐ and Ca‐montmorillonite exceeded predicted values. Subsequent decompression and recompression cycles were reversible except for a slight but measurable hysteresis, but the position of the reversible portion of the curve depended upon the terminal pressure of the initial compression. When the latter was large (25 to 50 atm.), measured swelling pressures of decompression‐recompression cycles for Na‐montmorillonite agreed quantitatively with theory over the range 0.2 to 50 atm. Under similar conditions, Ca‐montmorillonite exhibited pressures appreciably less than predicted by theory.
Annual Lupines and Other Cover Crops for the Forest Nurseries of the Lake States
Authors: Stoeckeler J. H.
Published: July 2010

Blue, white, and sweet yellow lupines were tested as a green manure crop in forest nurseries in northeastern Wisconsin and in Michigan. Besides lupines; vetch, soybeans, serradella, and rye were also tried. Sweet yellow lupine consistently gave the best performance, producing on the average about 4,392 pounds of oven‐dry bulk per acre with an average nitrogen content of 89 pounds per acre. Hairy vetch gave the best average yield but had the disadvantage of slow initial growth rate.
Moisture Depletion by Forest Cover on a Seasonally Saturated Ozark Ridge Soil
Authors: Fletcher P.W. , McDermott R. E.
Published: July 2010

Many broad, flat‐topped ridges in the Ozark Province of Missouri have a subsoil pan horizon at 2 to 4 feet beneath the soil surface. This pan limits the depth of root penetration and restricts water movement to deeper depths. Winter excesses of precipitation are held in and above the pan as a “perched” water table. Records from shallow wells showed that free water occurred within 3½ feet of the soil surface throughout most of the winter months, persisting almost continuously from November, 1954, to August, 1955, where the trees had been cut, and from December, 1954, to June, 1955, in the adjacent undisturbed forest. A dense stand of oak trees, 4 to 8 inches in diameter, having roots in this saturated zone, caused a pronounced diurnal fluctuation in the rate of recession of the water level during April and May. Estimates from this record, together with soil moisture records, indicated that evapotranspiration for this forest stand was 0.175 inches of water daily during rainless periods in April and May.
The Effect of Clay Minerals and Exchangeable Cations on the Adsorption of Ethylene Dibromide Vapor
Authors: Jurinak J. J.
Published: July 2010

A study was conducted to investigate the effect of clay mineral and exchangeable cation on the adsorption of ethylene dibromide (EDB) vapor by dehydrated clay. The Brunauer, Emmett, and Teller (BET) equation was applied to the data and the BET parameters Wm, n, and C evaluated. Both the exchangeable cation and the clay mineral had a pronounced effect on the adsorption process. Adsorption, in all cases, was confined to the external surfaces of the mineral systems.

The effect of Mg, Ca, and Na ions on the adsorption of EDB by montmorillonite was accredited to the varying amount of moisture retained by the homoionic clay systems after dehydration, the retained moisture being important in determining the extent and nature of the adsorbing surface.

The adsorption of EDB per unit surface by Ca‐montmorillonite, ‐illite, and ‐kaolinite indicated that adsorption on Ca‐montmorillonite is more restricted than on Cakaolinite, with Ca‐illite being intermediate. These data and the BET parameters support the view that the effect of clay minerals on EDB adsorption is a manifestation of the physical condition of the clay surface after dehydration. The montmorillonite system presenting a porous aggregate whose capillary dimensions restrict adsorption while the kaolinite system presents a relatively unrestricted planar surface for vapor adsorption.
Characteristics of Some Soils of the Arid Region of Washington
Authors: Gilkeson Raymond A. , Marshall Warren G. , Smith Henry W.
Published: July 2010

A study has been made of six soils selected for characterization by laboratory and field methods as representative of soil development in the arid region of south central Washington.

The parent materials are derived from several acid igneous, basic igneous, and metamorphic rock types, and range from glacial‐fluvial deposits to loess. The arid microthermal climate, with a mean annual precipitation of 6 to 9 inches, supported a sparse native vegetation of sagebrush and bunchgrasses.

The A horizons, as contrasted with the rest of the solum, have some accumulation of organic matter, darker colors, partial removal of bases but a significant increase in exchangeable potassium, and weakly developed granular or platy structure. Development of a B horizon is recognized on the basis of weak blocky or coarse prismatic structure, and, in contrast to the A horizon, higher pH, and lighter colors. Illuviation of clay is not apparent. Lower horizons are characterized by significant increases in exchangeable sodium, lighter colors, and stratified materials. The texture, number of horizons, depth of solum, and position and degree of development of the lime zone are related directly to the original deposition of the soil‐forming materials. These properties are presented as proper criteria for Sierozem soils.
The Partial Specific Volume of Water in Bentonite Suspensions
Authors: Low Philip F. , Anderson Duwayne M.
Published: July 2010

An equation was derived relating the partial specific volume of water in a clay suspension to the clay concentration and the suspension density. By means of this equation and the observed suspension densities at different clay concentrations, the partial specific volume of water was determined to be the same as that of pure water in Li‐, Na‐, and K‐clay suspensions at concentrations up to 0.14 g. of clay per cc. (13% clay).

From the above results it was possible to calculate the densities of Li‐, Na‐, and K‐clay. The respective densities were 2.71, 2.80, and 2.75.
Storage of Soil Samples and Its Effect upon the Subsequent Accumulation of Nitrate Nitrogen during Controlled Incubation
Authors: Harpstead M. I. , Brage B. L.
Published: July 2010

Ten South Dakota soils were investigated to determine the effect of prolonged storage under air‐dry conditions on the accumulation of nitrate nitrogen during subsequent laboratory incubation. Each soil was sieved and spread out in a drying cabinet where there was forced air circulation at room temperature. While the soils were still moist, as they occurred in the field, a sample of each soil was leached free of nitrate and incubated in a humid chamber for 14 days. Nitrate nitrogen which accumulated during the incubation period was determined. Similar incubations were made after soils had been stored at room temperature for 3, 6, 9, 18, 24, 34, and 50 weeks.

Results showed the nitrification rate of freshly‐collected soil was high compared to that after air‐drying and 3 weeks of storage prior to incubation. Subsequent incubations showed a progressive increase in the nitrification level. The precision of results among replicates improved with the length of storage. Prior to 18 weeks of storage the amount of nitrate nitrogen accumulated during incubations was not correlated with oat yield responses to nitrogen fertilization. Incubations made after 18 weeks of storage, however, yielded results which correlated with the response of oats to nitrogen fertilization.
Influence of Base Saturation and Calcium Levels on Yield and Mineral Content of Alfalfa
Authors: Dawson M. D.
Published: July 2010

A greenhouse investigation was carried out on four pedologically contrasting soils. The soils were limed to different base saturation levels. Yield and mineral composition were determined for the alfalfa grown on these soils.

Soil pH readings at the same base saturation levels varied considerably on the different soils. The pattern of alfalfa response to lime also varied. On the Brown Latosol optimum growth was obtained at 40% base saturation while the other three soils gave optimum growth at either 80 or 100% base saturation. The yield response was attributed to either the direct or indirect effects of lime. Concurrently a split‐root experiment was conducted to study the effects of additional calcium supplied to an isolated section of alfalfa roots at each base saturation level. Additional calcium supplied to isolated root sections independent of the soil increased alfalfa yield significantly on two soils. The addition of calcium to the roots also decreased the manganese content of the foliage.
Distribution and Nitrification of Anhydrous Ammonia in a Nicollet Sandy Clay Loam
Authors: McIntosh T. H. , Frederick L. R.
Published: July 2010

A roughly cylindrical distribution of NH3 centered at the knife openings was found when anhydrous ammonia was applied with a field applicator at a depth of 4 inches, by sampling an 8‐ by 8‐ by 2‐inch cross section perpendicular to the applicator row. NH4‐N, NO3‐N and pH were determined on each 1‐inch square subsample. NH4‐N decreased from a maximum concentration of 1,300 to 2,000 ppm. (pH 9.5) at the center to less than 200 ppm. (pH 8) in the area about 1½ inches away from the center of the retention zone. After 2 weeks, the maximum concentration of NH4‐N was about 800 ppm. (pH 8.8) in the center decreasing to less than 100 ppm. (pH 7.0) in the area about 2½ inches away from the center of the retention zone.

Nitrification initially proceeded more rapidly in the outside 2 inches of the retention zone where the concentration of NH4‐N was less than 400 ppm. Later in the original ammonia retention zone, nitrification appeared to be limited by low pH and nitrate concentration; at the end of 4 weeks the pH had decreased to a value of 5.0 to 5.5 and NO3‐N had increased until 200 to 300 ppm. were present. Ammonia applied in November just prior to freezing showed little nitrification by March. Rapid nitrification began in mid‐April when soil temperatures rose above 40° F. Approximately 8 weeks were required to completely nitrify the ammonia.
Ammonia‐Salt Systems as Nitrogenous Fertilizers
Authors: Zimmerman M. F. , Smith F. W. , Leonard G. W.
Published: July 2010

“Divers' solution” (an NH4NO3‐NH3 system); similar systems of NaI‐NH3, NH4I‐NH3, NaSCN‐NH3, NH4SCN‐NH3, NH4Br‐NH3; and three solid nitrogenous fertilizers (NH4NO3, CO(NH2)2, and urea‐form) were compared in the greenhouse as sources of nitrogen for wheat and millet plants.

The systems of NaSCN‐NH3, NH4SCN‐NH3, NH4I‐NH3, and NaI‐NH3 were very toxic for the first crop of plants. Lethal effects of NaSCN‐NH3 and NH4SCN‐NH3 disappeared in about 5 months. Both systems, NH4I‐NH3 and NaI‐NH3, were toxic for a longer period. Applications of NH4Br‐NH3 caused considerable wilting at first but no lethal effects occurred.

The greatest nitrogen percentage in wheat plants occurred from use of NH4Br‐NH3 but the greatest total accumulation in plants resulted from use of NH4NO3‐NH3. Urea‐form was ineffective as a source of nitrogen for the first crop. Solid ammonium nitrate and urea were of about the same effectiveness.

Herbicidal possibilities for some of the systems were suggested.
A Unifying Numerical Solution for Two‐Dimensional Steady Flow Problems in Porous Media With an Electrical Resistance Network
Authors: Bouwer Herman , Little W. C.
Published: July 2010

Numerical solutions of two‐dimensional steady flow systems that are partially or completely unsaturated involve satisfying the tension vs. conductivity relations of the media in addition to some approximative expression of the Laplace equation for nonhomogeneous conductivity. Where tensions and conductivities are initially unknown, assumed conductivity values are used in the first relaxation procedure after which the correct values are determined by a process of repeated relaxation analyses with conductivity to tension adjustments after each relaxation. Relatively rapid solutions can be obtained by use of an electrical resistance network for relaxing the system.

A numerical procedure is developed for expressing the equivalent conductivity of the medium between any two adjacent points of the network in terms of the conductivities or tensions at the two points. This procedure is independent of the nature of the relation between tension and conductivity and utilizes experimentally determined values in the form of graphs or tables.

The equivalent conductivity between adjacent points of the network differs from the arithmetic mean of the conductivities at the points, especially when the conductivity values are relatively far apart. The arithmetic mean appears to be an accurate measure of the equivalent conductivity only in event of horizontal flow with a linear relation between tension and conductivity.

Examples of completed analyses include a solution of flow in tile‐drained soil with the saturated and unsaturated zone united into one system and a solution of unsaturated subirrigation flow from perforated underground tubing in the presence of a deep water table. The shape of the water table in the drainage example was immaterial to the solution of the problem, but it could be evaluated after the analysis as the atmospheric‐pressure contour. The streamlines above the water table deviated from the vertical direction causing the flow rate across the water table to be nonuniform.
Effect of Gamma Radiation on Growth and Metabolism of Microorganisms in an Organic Soil
Authors: Stotzky G. , Mortensen J. L.
Published: July 2010

Samples of Rifle peat were irradiated with gamma rays from a Co60 source at doses of 2, 8, 32, 64, 128, and 250 kiloroentgens (kr.). The irradiated samples were incubated for 54 days, and periodic determinations were made on the rate of CO2 evolution, P and N mineralization, pH changes, and development of bacterial and fungal populations.

The radiation doses employed had no significant effect on development of the bacterial population, pH, mineralization of P, and evolution of CO2. Growth of the fungal population and ammonia utilization was increasingly inhibited by doses of 8 to 250 kr.

Gross changes in the metabolism of the soil microflora did not take place. Higher dose levels than those used in this study apparently are required for the sterilization of organic soils.
Cation‐Exchange Capacity and Exchangeable Cations in Piedmont Soils of North Carolina
Authors: Coleman N. T. , Weed S. B. , McCracken R. J.
Published: July 2010

Soils of the North Carolina Piedmont were analyzed for permanent‐ and pH‐dependent charge components of cation‐exchange capacity. Permanent charge was taken as the summation of exchangeable metal cations, including Al displaced upon leaching with a neutral salt solution; pH dependent charge was regarded as the amount of exchange acidity (BaCl2‐TEA) remaining after neutral salt leaching.

Well‐developed upland soils had small permanent charges and large pH dependent charges. For soils of a given sequence, the permanent‐charge/pH‐dependent charge ratios (B2 and above) were smallest for the red end member. Deeper horizons often had very large permanent charges, as did the B horizons of some Planosols. Latosolic soils had smaller permanent‐charge/pH‐dependent charge ratios than did Red‐Yellow Podzolics.

Permanent‐charge components of CEC were countered exclusively by metal cations. In acid soils Al predominated, while Ca and Mg neutralized most of the permanent charge in soils with pH's above 6. There were negligible amounts of electrostatically‐bonded H in any soil. Generally exchangeable Al increased with depth. Yellow Podzolic and Planosolic soils in particular tended to have large amounts of exchangeable Al in lower horizons.

Percentage base saturation concepts are discussed, the conclusion being that a saturation percentage based on permanent charge is preferred.
Exchangeable Potassium Levels in Vermiculite and K‐Depleted Micas, and Implications Relative to Potassium Levels in Soils
Authors: DeMumbrum L. E.
Published: July 2010

Fe‐ and Mg‐rich micas were depleted of K in the laboratory by the action of sodium tetraphenylboron, and the products were examined by X‐ray diffraction. A natural vermiculite was included in this study. Exchangeable K was determined in relation to total K where possible.

Nearly constant levels of exchangeable K were maintained by the vermiculite and weathered trioctahedral micas over the range of K concentrations at which fixation occurred. The materials functioned as K fixers below approximately 3% K2O but little fixation could be induced at moderate temperatures and K concentrations above 3% K2O. Total K below 3% K2O was not related to exchangeable K. Above 3% K2O, exchangeable K increased rapidly with K additions. Interstratified layer silicates were produced by K removal from the natural micas, and were also formed by additions of K to vermiculite. At natural levels of total K in the micas (7 to 10% K2O), 10Å. material was present; considerable 14Å. material was produced as removal of K approached completion.

Dilution of the fixing mineral with montmorillonite resulted in exchangeable K levels which were very similar to those in the fixing mineral alone. Numerous workers have noted that certain soils seem to exhibit characteristic exchangeable K levels which are not altered appreciably by additions or removals of K. These data tend to substantiate such observations and seem to explain the characteristic K exchange levels within such soils.
Aluminum Studies: II. The Extraction of Aluminum from Some Florida Soils
Authors: Yuan T. L. , Fiskell J. G. A.
Published: July 2010

A study of soil Al extraction by various chemical reagents has been conducted. Using N NH4OAc solutions buffered at six different pH levels, it was found that the lower the pH of the solution the more Al was extracted. Neutral normal solutions of BaCl2, CaCl2, KCl, NH4Cl, and a solution of BaCl2 in triethanolamine buffered at pH 8.1 extracted more Al than neutral N NH4OAc. Among neutral salts the bivalent cations seemed to be more efficient. BaCl2 in triethanolamine extracted much more Al than any of the neutral salts, probably due to the complexing capacity of triethanolamine.

Three alkaline reagents—NaOH, NaF, and Na pyrophosphate—commonly used for organic matter extraction, were also tested. Each of these reagents extracted much more Al from sandy and sandy loam soils than the previous reagent group. This Al was believed to originate from various Al compounds in soils including aluminum hydroxide and phosphate and even aluminum silicates.

In order to investigate the relationship between Al and phosphate release, a P‐fractionation procedure was used on a Red Bay fine sandy loam. In the extract of each fraction a high amount of Al was found, except with NH4Cl. Al hydroxide seemed to be the main source contributing to the high Al value obtained from alkalis and fluoride extractions.
Influence of Nitrogen Fertilization and Clipping on Grass Roots
Authors: Oswalt D. L. , Bertrand A. R. , Teel M. R.
Published: July 2010

Strategic placement of P32 and root excavations revealed that roots of orchardgrass and bromegrass reached a greater depth when no N was applied. Nitrogen increased the root diameter and decreased the rate of elongation causing the plants to feed near the soil surface for a longer period of time. Defoliation stopped root growth within 24 hours and induced decomposition of the existing roots within 36 to 48 hours. Uptake of P32 placed in the existing root zone 24 to 48 hours after clipping was not detected until new roots reached the activated zone. New roots were initiated from basal leaf nodes of orchardgrass and rhizome nodes of bromegrass. Removal of all roots at the time of defoliation did not influence the rate of regrowth from transplanted sod plugs under optimum soil moisture conditions.
Tests of Capillary Flow Scaling
Authors: Elrick D. E. , Scandrett J. H. , Miller E. E.
Published: July 2010

Four types of experiments testing predicted scaling relations are reported.

In the first two, different liquids are compared in the same medium. The first compares hysteresis loops—liquid content vs. tension. The second compares conductivities at a certain tension.

The third and fourth experiments concern entire flow systems; they compare systems constructed from different (but “similar”) media; only one liquid being used. The third experiment measures flow into the top of a dry column. The fourth measures drainage from a saturated column under a combination of tension and gravity.

The results of all four experiments are in excellent agreement with theory when the media are clean sands. The hysteresis experiment was also run for media having increasing colloidal fractions. In the latter cases, the results show definite departures from theory which increase with the amount of colloid.
The Influence of Organic Matter Additions on Rock Phosphate Availability to Crops
Authors: Seatz Lloyd F. , Sterges Athan J. , Kramer James C.
Published: July 2010

A greenhouse experiment was conducted to evaluate the effects of adding organic matter to the soil on the availability of rock phosphate from two sources. The treated soils were cropped successively to Sudangrass, ryegrass, and two crops of red clover. Treatments receiving additions of organic matter yielded higher in most cases than the corresponding treatment without added organic matter. Increased yields were attributed to the additional P in the organic matter rather than to the beneficial effect of the organic matter on the availability of rock phosphate. Treatments receiving Florida rock phosphate yielded more than corresponding treatments receiving Tennessee rock phosphate.
An Evaluation of Phosphorus Fertilizers Varying in Water Solubility: II. Broadcast Applications for Corn
Authors: Webb John R. , Pesek John T.
Published: July 2010

Sixteen field experiments were conducted, in which two or more phosphorus fertilizers differing in water solubility were compared in broadcast applications for corn. The tests involved rates of 20 to 80 pounds of available P2O5 per acre, and were located on soil types which tested low in available P and had a pH range from 5.5 to 7.1.

Increasing the rates of applied P2O5 increased the P content of corn leaf samples taken at silking time, but the degree of water solubility of the P significantly influenced leaf P levels in only 1 of 11 experiments sampled. Grain yields were also increased by P2O5 rates but were not significantly affected by the sources of P at any of the test sites. Highly water‐insoluble sources tended to be slightly less effective in a few of the experiments.

The general conclusion was that on the soils included in the study the degree of water solubility of the P was not an important factor in determining the effectiveness of fertilizers broadcast and plowed under for corn.
Influence of the Coarse Fraction in Two Maine Potato Soils on Infiltration, Runoff and Erosion
Authors: Grant Walter J. , Struchtemeyer Roland A.
Published: July 2010

The influence of the coarse material in Caribou and Thorndike soils on infiltration, runoff and erosion was studied with the use of a laboratory infiltrometer which applied water at 2.5 inches per hour but with energy of impact appreciably less than that in natural rain of the same intensity. Various sized coarse particles were removed from both soils to determine the function of the coarse fraction. There was a significant decrease in the rate of infiltration and likewise an increase in runoff as the particles > 12.7 mm. were removed from both soils. A further decrease in infiltration resulted when all material > 4.76 mm. was removed; however, the fraction between 4.76 mm. and 2.38 mm. did not have a significant effect on infiltration and runoff.

The amount of soil in the runoff from the Caribou sample was found to be nearly proportional to the runoff. It also increased with runoff as the coarse fractions were removed from the Thorndike soil, but there was not a significant increase for the second and third trials on the same sample even though the runoff increased. Some of the practical implications of the coarse fraction are discussed in relation to land use and the possible removal of coarse material for increased mechanization of farming operations.
Effect of Iron, Aluminum and Humic Acid on Phosphorus Fixation by Organic Soils
Authors: Larsen J. E. , Warren G. F. , Langston Ruble
Published: July 2010

Studies were conducted comparing the effects of Fe, Al, and humic acid on P fixation in two organic soils which had undergone different degrees of decomposition. It was shown that organic soils fix P similarly to other reported P‐fixing systems. Fe and/or Al additions increased phosphate fixation while humic acid resulted in an apparent negative absorption. Further, humic acid prevented absorption of P in the presence of limited quantities of Fe and Al.
Autotrophic Oxidation of Ammonium and Hydroxylamine
Authors: Engel M. S. , Alexander M.
Published: July 2010

Studies of resting cell suspensions of Nitrosomonas europaea have demonstrated that high concentrations of hydroxylamine are stoichiometrically converted to NO2. The oxidation proceeded most rapidly above pH 7.5 and was affected by altering the relative concentrations of substrate and bacterial cells. Nitrification of NH4‐nitrogen was retarded by increasing alkalinity and high substrate levels, but the inhibition is not as marked as observed for the NO2‐oxidizing chemoautotrophs. The NH4 oxidation by intact cells was not stimulated by Fe, orthophosphate, HCO3, Mg, Cu or Zn but was inhibited by small quantities of cyanide and 2,4‐dinitrophenol.
The Effects of Several Factors on Volatilization of Ammonia Formed from Urea in the Soil
Authors: Ernst J. W. , Massey H. F.
Published: July 2010

The effects of several environmental factors on the volatilization of ammonia from surface applications of urea on Dickson silt loam soil were studied under laboratory conditions.

Increasing temperature and/or soil pH markedly increased ammonia volatilization.

Ammonia volatilization from pH 6.5 soil was essentially the same when urea was topdressed, mixed with the top ¼ inch of soil or topdressed and watered into the soil with ¼ inch of water. Thus, it may be assumed that urea diffused through the soil to approximately the same extent with each of the three treatments.

Some ammonia volatilization occurred without a concurrent drying process in the soil, but greater volatilization occurred when moisture was lost from the soil. The drying rate, however, varied over a wide range without affecting the rate of ammonia volatilization. Under conditions of very rapid drying, the soil became dry after 4 to 5 days of aeration, and ammonia volatilization was markedly decreased, presumably because hydrolysis of the urea was retarded due to lack of moisture.

Ammonia volatilization was found to be directly related to initial soil moisture content presumably through the effect of this variable on the duration of the drying process.
Some Useful Techniques and Accessories for Adaptation of the Gas Chromatograph to Soil Nitrogen Studies
Authors: Smith Donald H. , Clark Francis E.
Published: July 2010

Sample‐handling procedures and certain modifications or accessories for the gas chromatograph that have been found useful in examining soil atmospheres for gaseous forms of nitrogen are described. Also described are columns and techniques that permit the separation and measurement of molecular N, N2O, NO, NO2, NH3, O2 and CO2. A special gas sampling valve, a manifold assembly, a multiple selector valve and a needle and manometer arrangement are diagrammed.
Cobalt Reactions with Montmorillonite
Authors: Hodgson J. F.
Published: July 2010

Specific reactions between montmorillonite and Co in low concentrations were studied in the presence of excess CaCl2. Two forms of bound Co were distinguished. One form, characterized as being slowly dissociable, appears to be bound in a monolayer by chemisorption and will exchange with Cu++, Zn++, or other Co++ and to a lesser extent with ions of other transition metals but not with Ca++, Mg++, or NH4+. A second form of Co did not dissociate and could not be extracted from the mineral with 2.5% acetic acid. This fraction, which was not characterized, is thought to either enter the crystal lattice or be occluded in the precipitation of another phase.
Phosphate Phase Equilibria in Soils
Authors: Lindsay W. L. , Moreno E. C.
Published: July 2010

The activity isotherms for AlPO4 · 2H2O (variscite), FePO4 · 2H2O (strengite), Ca10(PO4)6F2 (fluorapatite), Ca10(PO4)6(OH)2 (hydroxyapatite), Ca4H(PO4)3 · 3H2O (octocalcium phosphate), and CaHPO4 · 2H2O (dicalcium phosphate dihydrate) were represented on a single solubility diagram in which a function of the phosphate activity in solution was plotted against pH. This plot is useful for assessing the relative stabilities of these phosphate compounds and for predicting their transformations in soils upon the application of fertilizer or lime.

For this development, the assumptions were made that Al3+ activity in soils was limited by the solubility of gibbsite, the Fe3+ activity by the solubility of goethite, F‐ activity by that of fluorite, and the Ca++ activity was arbitrarily selected as that of a 0.005M solution of a monovalent salt. Equations and graphs are included for modifying the basic diagram so as to correspond to any Al3+, Fe3+, F‐, or Ca++ activity that may be found in soils or that may be established during a particular soil extraction.
Correlation of Nitrogen Soil Tests With Nitrogen Uptake by the Tobacco Plant
Authors: Peterson L. A. , Attoe O. J. , Ogden W. B.
Published: July 2010

Greenhouse and laboratory studies were conducted on soils collected from 37 Wisconsin tobacco fields to evaluate their capacity to supply nitrogen for two successive tobacco crops. Correlation analyses were made between the nitrogen content of each crop and the nitrogen determined by the various soil tests on the samples taken before the first crop. Highly significant correlation coefficients of 0.97 and 0.90 were obtained for soil nitrate nitrogen and Aspergillus niger tests, respectively. However, these tests were not significantly correlated with nitrogen uptake by the second crop, no doubt a result of depletion of the nitrates by the first crop. Similar results were obtained by dividing the soils into Prairie and Gray‐Brown Podzolic groups, except that a highly significant coefficient was obtained between the Aspergillus niger test and nitrogen uptake by the second crop for the Prairie soils. The tests which determined all or a portion of the organic nitrogen correlated at significant or highly significant levels with the nitrogen content of the second crop but not by the first crop. This lack of consistency between crops was undoubtedly due to the pronounced effect of the higher content of nitrate nitrogen in the soil prior to the first crop. Highly significant correlation coefficients were obtained between total soil nitrogen and each of the following: alkaline permanganate nitrogen (0.95), percentage organic matter (0.99), nitrification rate (0.65) and the amount of ammonia nitrogen extracted by various concentrations of sulfuric and hydrochloric acids (0.59 to 0.71).
The Significance of the Suspension Effect in the Uptake of Cations by Plants from Soil‐Water Systems
Authors: Olsen R. A. , Peech Michael
Published: July 2010

The significance of the suspension effect (greater cation concentration or activity in the soil suspension than in the equilibrium dialyzate) in determining the uptake of cations by plant roots was evaluated by comparing the rate of uptake of Rb+ and Ca++ by excised roots of barley and mung beans from a suspension of clay or cation‐exchange resin with that from the corresponding equilibrium dialyzate. Although the cation concentration of the clay or resin suspension greatly exceeded that of the corresponding equilibrium dialyzate, the rate of uptake of Rb+ or Ca++ by the roots was found to be exactly the same from both the suspension and its equilibrium dialyzate.

The results of this study are at variance with the prediction of the contact‐exchange theory but are in agreement with the deductions based on theoretical considerations of the consequences of the root surface or volume charge distribution. The significant conclusion that may be drawn, however, is that the composition of the soil solution or the equilibrium dialyzate should completely characterize the ionic environment of plant roots in soil‐water systems.
Determination of Reserve Sulfur and Soluble Sulfates in Soils
Authors: Bardsley C. E. , Lancaster J. D.
Published: July 2010

Organic and reduced inorganic sulfur (reserve sulfur) are converted to sulfates by ignition of a soil‐sodium bicarbonate mixture at 500° C. Converted and soluble sulfates (soil sulfur) are then extracted with a solution that is 2N to HAc and 0.1N to NaH2PO4·H2O and determined turbidimetrically as BaSO4 after acidifying a portion of the filtrate with 1:1 HCl. Acceptable recovery of sulfur has been obtained from elemental sulfur, plant material, methionine, cystine, and cysteine.

Soluble sulfates are extracted from a separate sample with 0.5N NH4OAc + 0.25N HAc. Activated charcoal is added to decolorize the extract. A portion of the filtrate is acidified with 1:1 HCl containing a “seed” solution of sulfate, and sulfur is determined turbidimetrically as BaSO4. Reserve sulfur is the difference between soil sulfur and soluble sulfates.

The multiple correlation of reserve and sulfate‐sulfur with total nitrogen in soils was highly significant (R = 0.971). Reserve sulfur was highly correlated with yield of sulfur from three harvests of white clover grown in the greenhouse (R = 0.790). The relation of reserve sulfur and sulfates to the sulfur status of soils is discussed.
Use of the Rainulator for Runoff Plot Research
Authors: Meyer L. Donald.
Published: July 2010

The portable rainfall simulator, known as the rainulator, which has been recently developed at Lafayette, Indiana, was designed for use as a research tool to aid in more rapidly evaluating factors that influence erosion, runoff, and infiltration. Intensities of 2½ or 5 inches per hour with near the kinetic energy of natural rainfall at these intensities are produced. Other characteristics which are desirable for runoff and erosion research on rectangular field plots are embodied in the design. The number and length of plots to which simulated rainfall may be applied simultaneously may be varied by varying the number of units used.

The rainulator will be used primarily for obtaining comparative evaluations of various topographic, soil, water, crop, and management factors under field plot conditions. Numerous factors are well suited to study by this method. The types of comparisons and evaluations which are and are not well adapted to study on rectangular field plots in general and specifically with the rainulator are also discussed.
Some Aspects of Phosphate Adsorption by Charcoal
Authors: Beaton J. D. , Peterson H. B. , Bauer Norman
Published: July 2010

As a basis for eventually evaluating the effect of charcoal, formed during forest fires, on the availability of phosphate ions in the soil, the thermodynamics of aqueous phosphate adsorption on six typical synthetic and natural charcoal materials is investigated. A standard adsorption process is defined under the justifiable assumptions that primary orthophosphate is specifically adsorbed, probably through hydrogen bonding; and that the counter‐ion, K+, is nonspecifically adsorbed or oriented in the diffuse double layer. Adsorption isotherm data at 25°, 35° and 45° C. and surface area measurements allow determinations of the changes in free energy, ΔF0θ, enthalpy, ΔH0θ and entropy, ΔS0θ for the standard adsorption process. This process is endothermic for the four most active charcoals. The shapes of the isotherms indicate that at least two types of adsorption sites or processes are involved, at high phosphate concentrations, in all cases. The four most active charcoals show an increase in adsorptive capacity with increasing temperature, associated with large positive values of ΔS0θ. X‐ray diffraction patterns show that the four most active charcoals have graphite‐like structures, whereas the other two seem to have, largely, a three‐dimensionally cross‐linked structure. The adsorption of phosphate per unit area increases in the order soil surface, lodgepole pine, duff, B & A Code 1551, Darco S51 and Darco G60 charcoals.

Theoretical interpretation of the thermodynamic data indicates that, at least for the four most active charcoals, an extensive dehydration of the phosphate and/or charcoal surface is a distinctive part of the adsorption mechanism.
Studies on Response of Legumes to Molybdenum and Lime Fertilization on Mardin Silt Loam Soil
Authors: Kliewer W. M. , Kennedy W. K.
Published: July 2010

Greenhouse experiments were conducted on Mardin silt loam to determine the response of alfalfa, birdsfoot trefoil, ladino and red clover to Mo applied alone and in combination with different increments of lime and P. Two strains of birdsfoot trefoil Rhizobium were also compared for differences in response to Mo and lime. These treatments were evaluated in terms of dry matter production and content of total N and Mo in forage and roots. The effect of these treatments on nodulation was studied with birdsfoot trefoil.

All legumes responded to Mo as shown by increases in yield and N content of forage and roots. Birdsfoot trefoil showed the greatest response to Mo. An interaction between Mo and lime was found for alfalfa, birdsfoot trefoil and ladino clover. Mo applied with lime at rates less than 2 tons per acre increased the yield and N content of the forage. However, at 2 tons of lime per acre or greater there was no response to the addition of Mo.

A direct relationship existed between soil pH and Mo content of the forage of birdsfoot trefoil. Four to five tenths ppm. Mo in the forage was found to be adequate for maximum growth.

Molybdenum increased the size of individual nodules and reduced the total number of nodules on birdsfoot trefoil plants. A correlation existed between the number of nodules per plant and the N content of the forage.

The strain of Rhizobium or level of P did not affect yields or N content of forage or roots.

Yields from treatments that received 2 tons of lime per acre were always greater than those receiving less lime, whether or not Mo was added. Yield and N data suggest that when lime was applied at a rate of 2 tons per acre or greater it had an additional effect besides increasing the availability of Mo, P, or providing a suitable environment for Rhizobia bacteria. This was especially pronounced in alfalfa and to a lesser degree with birdsfoot trefoil and the clovers. A possible reason for this is given in the discussion.
Slow Tests Under Soil Moisture Suction
Authors: McMurdie J. L. , Day P. R.
Published: July 2010

Standard Slow Tests using triaxial compression equipment were performed on three materials—a Yolo loam, a Hanford loamy sand, and two sizes of glass beads. The results were compared with Slow Tests in which part of the stresses were applied to the sample in the form of controlled soil moisture suction. The results were summarized in the form of Mohr diagrams plotted with respect to effective stresses calculated from the equation σ′ = σ − σw, where σ′, σ and σw are effective, mechanical (total), and soil water stresses, respectively.

Differences occurred not only in the case where the suction induced unsaturation (Hanford and glass beads) but also in the saturated range (Yolo). It was concluded that soil moisture suction was not in general equivalent to stresses applied mechanically to the external boundaries of the sample, as regards the strength property. Where the material remained saturated (Yolo) the departures increased with decreasing bulk specific volume. Where unsaturation occurred (Hanford, glass beads), the departures increased with decreasing degrees of saturation.
The Measurement of Exchangeable Aluminum in Soils and Clays
Authors: Lin Clara , Coleman N. T.
Published: July 2010

The 1N salt leaching of Al‐saturated soils and clay samples or of acid subsoil materials with native ion saturations resulted in the displacement of Al+++ions in amounts close to the exchange capacity for the Al‐saturated materials and near capacity minus exchangeable Ca + Mg for the acid subsoils. Prolonged leaching with neutral salt solutions did not displace quantities of Al significantly larger than those which were present on exchange sites. Acidified salt solutions, on the other hand, continued to dissolve Al. One normal solutions of KCl, CaCl2 and NaCl removed the same amounts of Al from a number of soils and clays, so long as the leaching was sufficiently exhaustive. For limited leaching, KCl was the most effective displacing agent and NaCl the least.

Potentiometric titrations of some Al‐saturated or naturally acid soils and clays to pH6 in 1N KCl consumed quantities of base equivalent to the Al displaced by salt‐leaching or determined by conductimetric titration. With other soils, containing mostly kaolin minerals and iron oxides, the acidity which could be titrated was significantly larger than the amount of Al which could be displaced.
Uptake of Potassium by Red Pine Seedlings and Losses Through Leaching from Fertilizers of Various Solubility
Authors: Krause H. H. , Wilde S. A.
Published: July 2010

The uptake of K by red pine seedlings and the losses through leaching from irrigated, coarse‐textured soil treated with fertilizers of different solubility were determined by plant tissue analyses and by the use of tension lysimeters. Potassium chloride, potassium‐calcium metaphosphate and 20‐mesh syenitic granite were used as sources of K. Considerable fractions of K were lost from applications of readily soluble KCl. The pattern of K leaching followed the rate of nitrification in the soil. Potassium metaphosphate possessed a greater stability and fertilizing value than KCl. The fraction of available K of the applied granite became exhausted during the second growing season.
Ion Exchange Equilibria Involving Aluminum
Authors: Nye Peter , Craig Doris , Coleman N. T. , Ragland John L.
Published: July 2010

Exchange isotherms determined for the K‐A1 ion pair with montmorillonite, kaolinite and two soils were S‐shaped. In dilute solutions (<0.05N), A1 was strongly preferred by exchange sites except at low levels of K‐saturation. In more concentrated solutions (0.1 to 0.25N), K was preferred when its saturation was less than about 30%, while A1 was more strongly sorbed over the remainder of the isotherms. In 1N solution, K was bound more tightly than A1 over the entire range of ion saturation up to at least 90% K‐10% A1.

In both dilute and concentrated solutions, A1 was preferred over Ca. In 1N solution, A1 was bound much more tightly than Na. Because of the strong sorption of K, competing with A1 in concentrated solution, KCl should be an effective displacing agent for exchangeable A1.

Exchange coefficients for the K‐A1 reaction, calculated according to the “equivalent fraction” equation, varied greatly, both with electrolyte concentration and exchange site population. The isotherms, though not described by a simple equation, are regarded as valuable indices of the exchange behavior of acid clays and soils.