bluuebunny/crossref_metadata_2025 huggingface dataset:
X‐Ray Studies of Crystalline Swelling in Montmorillonites
Authors: Fink D. H. , Thomas G. W.
Published: July 2010

Swelling properties of several montmorillonites (Li‐, Na‐, or Ca‐saturated) in water systems were studied using low‐angle X‐ray diffraction. All Li‐montmorillonites expanded linearly with water contents greater than 35%. Sodium‐hectorite also exhibited similar expansion. Sodium‐saturated Otay and Wyoming bentonites and nontronite, however, showed step‐wise expansion to about 110% water, and linear expansion at higher water contents. All calcium montmorillonites expanded in a step‐wise manner to a maximum spacing of about 20Å. The experimental techniques also were applied to the swelling properties of soil clays known to be high in montmorillonite. Results suggest that the poor crystallinity of soil montmorillonites is much more apparent at high water contents.
Fixation of Hydroxy‐Aluminum Polymers by Vermiculite
Authors: Hsu Pa Ho , Bates T. F.
Published: July 2010

The addition of vermiculite to hydroxy‐aluminum (OH‐Al) solutions prepared by the controlled addition of NaOH to AlCl3 results in the fixation of OH‐Al polymers by the clay. With solutions of NaOH/Al molar ratios = 0.3 to 2.1, the polymers held by the clay are of nearly constant composition, very close to the formula [Al6(OH)12]6+ (single ring) or [Al10(OH)22]8+ (double ring). The polymers are present in a single layer in the interlayer space. All specimens give a strong 14Å. X‐ray diffraction peak of similar intensity on K+ saturation even though the proportion of cation‐exchange positions occupied by the OH‐Al polymers varies from 24% to 61% on an equivalent basis.

With solutions of NaOH/Al = 2.25 to 2.70, the polymers held by clay gradually increase in size and decrease in net positive charge per Al atom with increasing NaOH/Al ratio. The polymers are also present in a single layer in the interlayer space, but it takes more Al atoms and a longer time for the polymers in this group to produce a 14Å. peak of an intensity corresponding to that obtained when the Al is in the form of single or double ring units. In those specimens in which the amount of Al fixed is not sufficient to hold the vermiculite layer apart effectively, the Al polymer‐vermiculite layer is randomly interstratified with K‐vermiculite, and the resultant X‐ray diffraction patterns vary widely, some appearing as though X‐ray amorphous components were present.

For all of the above mentioned specimens, no noticeable change has been found in the composition of the polymers held by clay minerals during aging up to 6 months. No crystalline Al(OH)3 was detected in any of these specimens. It is concluded that vermiculite functions as an anion which has a strong affinity for OH‐Al polymers and which inhibits the formation of gibbsite in soils.

At NaOH/Al = 3, no OH‐Al polymer is found in the interlayer space but crystalline Al(OH)3 forms outside the clay lattice within two weeks.
Nitrosation of Soil Organic Matter: I. Nature of Gases Evolved During Nitrous Acid Treatment of Lignins and Humic Substances
Authors: Stevenson F. J. , Swaby R. J.
Published: July 2010

Manometric and infrared studies of the gaseous products formed by reacting HNO2 with humic and fulvic acids, lignins. lignin‐building units, and polyphenols showed the presence of N2, N2O, and CO2. In addition, methyl nitrite (CH3ONO) occurred in the gases obtained from lignins and certain phenolic derivatives. The CH3ONO originated through dismutation of phenolic ethers; the CO2 from decarboxylation of aromatic acids and cleavage of ring structures. Aromatic‐like substances interfere with the determination of free amino groups in soil organic matter by the Van Slyke nitrous acid method.
Soil Surface Patterns of some Semiarid Soils in Northern Utah, Southern Idaho, and Northeastern Nevada
Authors: Hugie V. K. , Passey H. B.
Published: July 2010

Surface soil patterns were classified and studied on 70 semiarid to subhumid areas with relict native vegetation in Utah, Idaho, and Nevada. Three general classes of soil surface conditions were recognized — prominently patterned, weakly patterned, and unpatterned. Prominent and weak patterns were further classified into polygonal surface soil patterns with and without segregation of coarse particles.

Surface patterns were found to occur only on bare surface soil between clumps of plants on well‐drained and moderately well‐drained silt loam, silty clay loam, and very fine sandy loam textured soils. Polygonal patterns with segregated coarse particles were observed only on moderately well‐drained planosolic, lithosolic, and solonetzic soils containing basalt pebbles. Surface soil patterns did not occur under vegetation, mulch, stones, or gravel.

Cycles of alternate freezing and thawing of the surface soil followed by desiccation result in the formation of polygonal surface soil patterns with and without segregation of coarse particles.
Influence of Rainfall Energy on Soil Loss and Infiltration Rates: I. Effect over a Range of Texture
Authors: Moldenhauer W. C. , Long D. C.
Published: July 2010

Soil and water losses were determined from sieved air‐dry samples of five Iowa soils varying in texture using a laboratory rain simulator with a 3‐m. drop fall, a 4.85 to 5.00 mm. drop diameter, and an intensity ranging from 3.43 to 6.78 cm. per hour. The soil samples were contained in a pan 15.2 cm. deep, 30.5 cm. wide and 45.7 cm. long and tilted to a 9% slope. Runs were 90 minutes in length. The infiltration rate was the most important factor influencing total soil loss. Relative total soil losses for 90 minutes of run at high intensity were silty clay > silty clay loam > silt > loam > fine sand. At the low intensity, the positions of silty clay and silty clay loam and of silt and loam were reversed. Total soil loss varied with intensity, but infiltration was essentially constant over the entire range except on the fine sand. With equal water loss the order of erodibility was find sand > silty clay > silty clay loam > silt > loam. Total kinetic energy required to initiate runoff was constant over a range of time and intensity.
Measurement of Sediment Density by Attenuation of Transmitted Gamma Rays
Authors: McHenry J. Roger , Dendy Farris E.
Published: July 2010

The measurement of density by observing the attenuation of transmitted gamma rays was adapted to the measurement of sediment density. A dual probe, utilizing transmission techniques, was evaluated for use in measuring the density of sediments collected from runoff of plots or small watersheds. The equipment consists of a 7‐mc. cesium137 source placed in one access tube and a probe containing a NaI scintillation crystal, photomultiplier tube, and preamplifier in the second tube. The high‐voltage power supply and scaler ratemeter for readout are supplied in a portable unit powered by silver‐cadmium recharge‐able dry cells. Cesium137 gamma radiation is measured by employing electronic discrimination to eliminate all phostons of energies below about 0.65 Mev. Sediment densities were measured in silt boxes installed on a small watershed at the North Mississippi Branch Experiment Station, Holly Springs, Mississippi, following laboratory calibration tests. The dual probe employed measured densities of sediments to within 0.01 absolute density units. The vertical resolution of the apparatus is less than I inch so that density measurements of thin layers and of materials at interfaces can be made. In one field test sediment weights, of the order of 8,500 pounds, computed for a silt box on the basis of dual probe density determinations varied less than 1% from a gravimetric determination. Changes in sediment density with time, with additional increments of sediment, and with storms were effectively measured.
Precipitation of Phosphate by Iron Oxide and Aluminum Hydroxide from Solutions Containing Calcium and Potassium
Authors: Taylor A. W. , Gurney E. L.
Published: July 2010

When acidic calcium phosphate solutions such as those formed by the dissolution of fertilizers react with aluminum hydroxide in the presence of little potassium, all the potassium is precipitated as taranakite, K3Al5H6(PO4)8·18H2O; most of the rest of the phosphate is precipitated as aluminum and calcium aluminum phosphates. In the presence of considerable potassium, the precipitation of phosphate is governed by the initial composition of the solution; as much as 25% of the phosphate is precipitated as dicalcium phosphate and most of the rest is precipitated as taranakite. Iron oxide reacts much more slowly with phosphate than aluminum hydroxide and has much less effect on the precipitation of phosphate.
The Effect of Periodate Oxidation on the Strength of Soil Crumbs: I. Qualitative Studies
Authors: Clapp C. E. , Emerson W. W.
Published: July 2010

Various methods of extraction and oxidation of soil organic matter were used in combination with a sodium saturation technique to assess the binding strength of wet soil crumbs. The procedure consisted of equilibrating a few 3‐ to 5‐mm crumbs with 0.05m NaCl, treating the crumbs with chemical reagents to remove the effective stabilizing components, and then observing the degree of slaking and dispersion of the crumbs when the sodium ion concentration is reduced. For crumbs from predominantly montmorillonitic or illitic soils, the dispersion solution was either 0.01m NaCl buffered with p‐nitrophenol at pH 7 or 0.025m Na2B4O7 at pH 10. For kaolinitic soils a more severe dispersion technique was required.

The stability of crumbs formed under long‐term grass was reduced greatly by oxidation of the organic matter with 0.05m NaIO4 followed by extraction with Na2B4O7. Complete dispersion in Na2B4O7 or NaCl/Na p‐nitrophenol was obtained when a preliminary extraction with neutral Na4P2O7 was followed by periodate oxidation. The stability of corresponding cultivated crumbs was destroyed completely without pyrophosphate extraction in a shorter period of oxidation. Surface crumbs from wooded sites on the same soils showed extreme resistance to all treatment combinations. It appears that there are two types of polymeric organic material binding the grassland crumbs together, one extractable by pyrophosphate and the other oxidizable by periodate.

Samples from Houston Black clay behaved anomalously until the CaCO3 was removed by dilute HCl treatment in the cold. The latter process in itself caused no loss in strength of the crumbs.
The Effect of Periodate Oxidation on the Strength of Soil Crumbs: II. Quantitative Studies
Authors: Clapp C. E. , Emerson W. W.
Published: July 2010

The rate of consumption of sodium periodate by Fargo clay loam surface grassland crumbs was measured at different periodate concentrations, and the degree of subsequent slaking and dispersion of the crumbs in 0.01m NaCl/Na p‐nitrophenol was observed. Prior leaching of the crumbs with 0.05m NaCl was essential before crumb stability was reduced appreciably 0.250 mmoles of periodate per gram of soil.

Release of the effective inorganic and organic binding agents by NaCl, Na4P2O7, and NaIO4 treatments was studied quantitatively. The effect of periodate oxidation alone was demonstrated when no measurable release of organic matter occurred with preliminary leaching by 0.05m NaCl. The amount of periodate consumed by the grassland crumbs was more than could be accounted for by primary oxidation of the carbohydrate present.

The loss in strength for the grassland crumbs, after systematic removal of the binding agents, was measured quantitatively by means of a plummer balance. The effect of prior leaching with 1m NaCl followed by 0.05m NaCl also was investigated. After the combined treatments, dispersion was still incomplete for the Fargo crumbs, indicating some residual bonding. The dispersion of Houston Black clay crumbs was complete, however, when 0.1m Na4P2O7 was substituted for 1m NaCl. The organic material released by either NaCl or Na4P2O7 stabilized the claysized fraction of the soil only. The periodate‐oxidizable substances stabilized both the silt‐ and clay‐sized fractions.
Aluminum in Soils: VII. Interrelationships of Organic Matter, Liming, and Extractable Aluminum with “Permanent Charge” (KCl) and pH‐Dependent Cation‐Exchange Capacity of Surface Soils
Authors: McLean E. O. , Reicosky D. C. , Lakshmanan C.
Published: July 2010

Seven Ohio surface soils which had been incubated with little or no lime and with sufficient quantities to nearly neutralize them were analyzed for “permanent charge” or KCl‐ and pH‐dependent cation‐exchange capacity (CEC). The low‐ and high‐lime soils were also analyzed for both of these components of CEC after organic matter was destroyed with hydrogen peroxide. CEC was also determined by extraction with 1n NH4OAc‐pH 7.

Changes in both the KCl‐CEC and pH‐dependent CEC caused by liming and by destruction of organic matter appeared to be the result of activation or inactivation of exchange sites of the organic matter initially occupied by Al. Only in the case of one soil (Venango, A2 horizon) did hydroxy‐Al appear to be equal to organic matter in effect on pH‐dependent CEC.
Gradient Elution of Soil Phosphorus
Authors: Avnimelech Y. , Hagin J.
Published: July 2010

Soil phosphorus was fractionated by the means of gradient elution technique used in chromatography. This method involves a nonequilibrium extraction of the soil P, whereas conventional methods are based on equilibrium extraction. Non‐equilibrium extraction is needed in order to describe the fate of the applied P before it reaches equilibrium with the entire soil system.

Soil samples were leached with a solution of linearily increasing acidity. Thus soil P was fractionated according to its solubility in acid. Upon leaching a soil sample, fertilized with superphosphate, two steps in P fixation could be demonstrated. The first step was a rapid one, decreasing the water solubility of the P, yet keeping it soluble in mildly acidic solutions. In the second slower step, P solubility in acidic solutions was decreased.
Decomposition and Binding Action of Polysaccharides from Azotobacter Indicus (Beijerinckia) and Other Bacteria in Soil
Authors: Martin J. P. , Ervin J. O. , Shepherd R. A.
Published: July 2010

The decomposition rate and binding effect in soil of a polysaccharide synthesized by A. indicus (Beijerinckia) were compared with those of other bacterial polysaccharides, including one from Chromobacterium violaceum and with other type organic materials. In acid and neutral soils an average of 19% of the A. indicus polysaccharide decomposed in 8 weeks. This compared with averages of 38%, 39%, 51%, 67%, and 84% decomposition for almond shells, C. violaceum polysaccharide, corn stalks, Azotobacter chroococcum polysaccharide, and glucose, respectively. Of these and additional organic materials tested, only peat moss was more resistant to decomposition than the A. indicus polysaccharide. All the bacterial polysaccharides were highly effective in binding soil particles into water stable aggregates. After 30 days of incubation A. indicus polysaccharide reduced numbers or had little effect on bacteria and fungi developing on soil dilution plates. Growth of fungi from soil dilutions on media containing no carbohydrate was as good or better than on the same medium containing poly‐saccharide from A. indicus or C. violaceum. Polysaccharides from A. indicus, C. violaceum, and B. subtilis reduced germination and/or growth of soil bacteria on agar media.
The Carbonyl Group in a Soil Organic Matter Preparation
Authors: Schnitzer M. , Skinner S. I. M.
Published: July 2010

The 2,4‐dinitrophenylhydrazone, phenylhydrazone, semicarbazone, and oxime of organic matter extracted from a Podzol Bh horizon were prepared. The four derivatives were analyzed by ultimate analysis, infrared, ultraviolet, and visible spectroscopy, and by X‐ray diffraction analysis.

The formation of derivatives was checked by increases in nitrogen content over that in the original organic matter. In the case of the 2,4‐dinitrophenylhydrazone a spectrophotometric method, specific for the derivative, was also used. The number of ketonic C=O groups per mole of original organic matter as determined by analysis of the 2,4‐dinitrophenylhydrazone was 2.1, of the phenylhydrazone 2.5, of the semicarbazone 2.0, and of the oxime 2.2. The presence of C=N bonds, symptomatic of derivative formation, was indicated in the infrared spectra. Evidence for the formation of the derivatives was also provided in some of the ultraviolet spectra and in one visible spectrum. X‐ray diffraction analysis of the original organic matter and of the derivatives indicated that these materials were amorphous.

On the basis of reductive acetylation, followed by infrared analysis of the product, and from reductometric titrations it was concluded that this organic matter did not contain measurable amounts of quinone groups and that the groups that had reacted with the reagents were ketonic carbonyl groups.
Nitrogen Carriers: I. Soil Effects
Authors: Wolcott A. R. , Foth H. D. , Davis J. F. , Shickluna J. C.
Published: July 2010

Replicated field plots on moderately acid sandy loam soils were sampled after 3 to 7 years' annually repeated applications of eight nitrogen sources at rates of 40 to 300 lb N/acre. Soil pH, exchangeable K, Ca and Mg, and lime requirement to pH 6.5 were measured. Acidifying effects to a depth of 15 inches were of the order: (NH4)2SO4 > NH4Cl > NH4NO3 ≊ NH3 ≊ urea > ureaform. Residual basicity from Ca(NO3)2 and NaNO3 was approximately equal to the acidifying potential of climate and management.

Observed declines in exchangeable bases were ⅓ to ½ the calculated equivalent acidity of acidifying carriers; increases in lime requirement were 1.5 to 6 times greater than calculated. Major increases in lime requirement occurred below the pH range 5.0 to 5.5 and were ascribed to retention of protons in the form of ionic complexes with Al and Fe. Uniquely greater residual acidity from (NH4)2SO4 may have been due to greater exchange affinity and base displacement by hydroxy‐Al‐SO4 complexes as compared with complexes with monovalent anions (Cl‐, NO3‐).

It is proposed that a fundamental objective of liming practice is to maintain soil pH well above the range where pathways of proton transfer are dominated by mobile sesquioxide buffer systems.
Effect of Temperature on the Occurrence of Phosphorus‐Induced Zinc Deficiency
Authors: Martin W. E. , McLean J. G. , Quick James
Published: July 2010

Greenhouse studies with tomato plants as indicators have been carried out to study the influence of temperature upon occurrence of phosphorus‐induced zinc deficiency. The soils used were from areas in commercial potato fields where “fern leaf” and chlorosis due to Zn deficiency has been observed. The soils were found to be concurrently deficient in both P and Zn. Field soil treatments with Zn caused a marked improvement in growth.

The effects of several rates of P, with and without Zn, upon tomato plant growth have been studied at 50, 60, 70 and 80F. Results on soil with moderately low (0.9 ppm) dithizone extractable Zn show P to induce Zn deficiency symptoms at 50 and 60F but not at 70 and 80F, although some growth differences attributable to Zn occurred at the higher temperatures. On soil from an acutely Zn deficient area (0.1 ppm Zn), P‐induced Zn deficiency was observed at all temperatures.

Phosphorus applications were observed to reduce Zn concentration in the tissue while Zn applications tended to reduce P concentration. Stunted plants showing acute Zn deficiency symptoms had about the same Zn and P concentrations on the dry weight basis as did normal appearing plants grown at higher soil temperatures with the same P treatments.
Radial‐Flow Cell—Further Tests
Authors: Miklich F. J. , Richards L. A.
Published: July 2010

Additional information has been obtained on the use of the radial‐flow cell for measuring capillary conductivity and soil‐water diffusivity. The equations used for describing unsaturated flow and the assumptions made in applying the equations to the transient outflow that occurs from the radial cell were described in a previous paper along with procedures for handling samples. Experience with both the linear‐outflow method and the radial‐outflow method indicates that the mathematical expressions developed to date do not accurately describe the transient outflow process. The reasons for the discrepancies are not fully understood.
Change of Phosphate Potentials of Calcareous Soils on Adding Phosphorus
Authors: Withee L. V. , Ellis Roscoe
Published: July 2010

In two calcareous soils studied the phosphate potentials (0.5 pCa + pH2PO4) and lime potentials (pH − 0.5 pCa) indicated that the forms of mineral phosphates that determine the amount of phosphorus in solution were basic calcium phosphates similar in solubility to octocalcium phosphate, Ca4H(PO4)3·3H2O. Phosphorus as H3PO4 added to the soils at the rate of 200 ppm P saturated them with respect to octocalcium phosphate, and 500 ppm P saturated them with respect to dicalcium phosphate. Wetting and drying the soils for 5, 10, or 20 cycles after adding phosphorus increased the phosphate potentials. No tendency for calcium phosphates to convert to hydroxyapatite was observed after 20 wetting and drying cycles. Repeated extraction of soil samples—some in their original condition and some to which phosphorus was added—with 0.01m CaCl2 solution increased their phosphate potentials. The dominant form of calcium phosphate in the soil to which phosphorus had been added changed with extraction from dicalcium phosphate to a form or mixture of forms intermediate between dicalcium and octocalcium phosphate.
Nitric Oxide Adsorption by Clay Minerals
Authors: Mortland M. M.
Published: July 2010

Nitric oxide was found to be chemically adsorbed on mont‐morillonite and nontronite when the exchange complex was saturated with certain transition metal ions. Infrared data showed a number of reactions depending on the nature of the saturating ion including: (i) coordination of NO as the mono or dinitrosyl complex; (ii) formation of N2O; (iii) formation of (NO)+. The NO molecule was able to penetrate the interlamellar regions of Co‐montmorillonite or Co‐nontronite. On all other systems, apparently only surface adsorption occurred. When air was admitted, all surface‐adsorbed NO was immediately oxidized, but interlamellar NO decreased at a rate apparently dependent upon the diffusion of NO to the clay mineral surface. A produce of oxidation was found to be coordinated nitrite.
Gibbsite, Bayerite, and Nordstrandite Formation as Affected by Anions, pH, and Mineral Surfaces
Authors: Barnhisel R. I. , Rich C. I.
Published: July 2010

X‐ray diffraction, differential thermal, and chemical analysis indicate that the pH, presence of anions or salt, and mineral surfaces have important roles in the formation of crystalline Al(OH)3 polymorphs from Al‐interlayers and/or hydroxy‐Al polymers.

Hydroxy‐Al was introduced into kaolinite, quartz, and montmorillonite systems by slowly adding appropriate amounts of AlC3 and NaOH (or OH‐resin) into rapidly stirred suspensions. Systems having various OH/Al molar ratios were prepared, and they were aged 0, 1, 3, and 6 months.

The pH or OH/Al molar ratio had the greatest influence on controlling the relative amounts of gibbsite and bayerite that crystallized in the various systems. Gibbsite crystallized better in acid environments, nordstrandite in slightly acid to neutral, and bayerite in basic environments. Nordstrandite also crystallized under acid conditions in systems having relatively low amounts of Na+ and Cl‐ ions.

Mineral surfaces and/or interlayer water structures, in addition to anions or salt, control the degree of crystallinity of the various Al(OH)3 polymorphs.
Importance of Carbon Dioxide in Uptake of Calcium by Plants Receiving Only a Nitrate Source of Nitrogen
Authors: Bartlett R. J.
Published: July 2010

Calcium deficiency was induced in maize seedlings (Zea mays L.) growing with roots in contact with limestone gravel or CaCO3 in suspension. This was done by supplying N in the nitrate form and by extreme aeration to prevent CO2 accumulation. The probable cause of the deficiency was the tendency of nitrate nutrition to maintain the pH of the alkaline medium, preventing solubilization of CaCO3.

When CO2 was allowed to build up in the suspension or limestone gravel culture, pH was lowered during growth, Ca became more soluble and deficiency of Ca in plants receiving nitrate nitrogen was corrected.

Substitution of ammonium for nitrate in CaCO3 suspension similarly corrected Ca deficiency. This resulted as ammonium uptake lowered pH and solubilized Ca.

Though unappreciated in this role because of their universal presence in the soil, both CO2 and ammonium N may be important in increasing the availability of Ca.
Assessing Wind Erosion Forces: Directions and Relative Magnitudes
Authors: Skidmore E. L.
Published: July 2010

Wind erosion force vectors were computed from data of frequency of occurrence of directions by windspeed groups based on wind erosion being proportional to windspeed cubed times the duration of the wind. The vectors were obtained by evaluating Σ Ū13 f1 for each of the 16 principal directions where Ū13 is the cubed mean windspeed within the ith speed group and f1 is percentage of total observations that occur in the speed group and direction under consideration.

The wind erosion force vectors were used to compute monthly magnitudes of the total wind erosion forces and direction where the ratio of the wind erosion forces parallel and perpendicular to that direction is a maximum. The computed direction indicates proper orientation of a wind barrier for maximum barrier protection. The magnitude of the ratio gives the preponderance of wind erosion forces in the direction of maximum wind erosion forces. The magnitude of the total wind erosion forces indicates the potential need for protection against the erosion forces.
A Wind Erosion Equation
Authors: Woodruff N. P. , Siddoway F. H.
Published: July 2010

The amount of erosion, E, expressed in tons per acre per annum, that will occur from a given agricultural field can be expressed in terms of equivalent variables as: E = f(I′, K′, C′, L′, V) where I′ is a soil erodibility index, K′ is a soil ridge rougness factor, C′ is a climatic factor, L′ is field length along the prevailing wind erosion direction, and V is equivalent quantity of vegetative cover. The 5 equivalent variables are obtained by grouping some and converting others of the 11 primary variables now known to govern wind erodibility. Relations among variables are extremely complex. Charts and tables have been developed to permit graphical solutions of the equation. The equation is designed to serve the twofold purpose of providing a tool to (i) determine the potential erosion from a particular field, and (ii) determine what field conditions of soil cloddiness, roughness, vegetative cover, sheltering by barriers, or width and orientation of field are necessary to reduce potential erosion to a tolerable amount. Examples of these applications of the equation are presented. Weaknesses in the equation and areas needing further research are discussed.
Zonal Salinization of the Root System in Relation to Plant Growth
Authors: Lunin J. , Gallatin M. H.
Published: July 2010

Corn and tomatoes were grown in the greenhouses in boxes containing three horizontal soil zones with a layer of coarse quartz sand to separate the zones. Either fresh or saline waters were supplied to each soil zone through porous ceramic tubes to maintain a fairly uniform water suction in each zone. Introduction of saline water into a given zone caused the uptake of water by the plant from that zone to decrease as soil salinity increased to a critical value, at which point water uptake ceased. The amount of water taken up by the plant from the nonsaline zones increased so that the total amount of water taken up by the plants was slightly less where one‐third of the soil was salinized as compared with the nonsalinized treatment. Water uptake further decreased where two‐thirds of the root system was salinized. Plant growth was unaffected when one–third of the root system was salinized, and yields were only slightly decreased when two‐thirds of the root system was salinized. Excessive salinization of the surface soil did not affect water uptake. Water uptake by tomatoes was more affected by zonal salinization than was corn.
Micronutrient Cation Complexes in Soil Solution: Partition Between Complexed and Uncomplexed Forms by Solvent Extraction
Authors: Hodgson J. F. , Geering H. R. , Norvell W. A.
Published: July 2010

Procedures were developed for the partition of heavy metals (Cu, Co, and Zn) between complexed and uncomplexed forms in soil solution. Competition for the above cations by complexing agents naturally present in soil solution and added complexing agents that form metal complexes soluble in organic solvents was determined by measuring the distribution of metal between aqueous and organic phases in a two‐phase system. The degree to which the metal was complexed in the original soil solution could be deduced by comparing the amount of metal extracted from soil solution with that extracted from water at the same pH. Examination of soil solutions from several mineral soils indicated that in the case of Cu as much as 99% of the metal may exist in a complexed form.
The Influence of Temperature and Time on the Adsorption of Paraquat, Diquat, 2,4‐D and Prometone by Clays, Charcoal, and an Anion‐Exchange Resin
Authors: Weber J. B. , Perry P. W. , Upchurch R. P.
Published: July 2010

The effects of temperature and exposure time on the adsorption of four organic compounds by montmorillonite, kaolinite, charcoal, and an anion‐exchange resin in a phosphate buffer of pH 6.0 were investigated. Organic cations (diquat and paraquat) were preferentially adsorbed by the clays up to the cationexchange capacity. Adsorption appeared to be one of ion exchange. X‐ray analysis indicated the cations were held in the lattice of the montmorillonite with the plane of the ring parallel to the silicate sheets. An organic anion (2,4‐D) was negatively adsorbed by the clays; and a s‐triazine compound (prometone) in molecular form, was adsorbed by montmorillonite but not kaolinite. X‐ray analysis indicated that prometone was located within the clay lattice but the orientation was uncertain. The adsorption mechanism was physical in nature being temperature dependent.

The 2,4‐D was adsorbed by the anion‐exchange resin through ion exchange forces and the equilibrium was influenced by temperature and exposure time. Prometone was adsorbed by the anion‐exchange resin to a much lesser degree, was also temperature and time dependent, and appeared to be physically bound.

All of the organic compounds were adsorbed by charcoal and each was influenced differently by temperature and exposure time.
Use of Amorphous Material to Identify Spodic Horizons
Authors: Franzmeier D. P. , Hajek B. F. , Simonson C. H.
Published: July 2010

The illuvial amorphous material that occurs as pellets or grain coatings in the B horizons of some New York Podzols contains much carbon, iron, and aluminum. This amorphous material has high cation‐exchange capacity (CEC) that can be destroyed by heat treatment or extraction with solutions of a complexing agent (citrate or pyrophosphate) combined with a reducing agent (dithionite). Most of the carbon, iron, and aluminum of the amorphous material is removed with extracting solutions.

The study included 19 New York soils, ranging from those with strong spodic horizons to those with cambic horizons. In the uppermost B2 horizon of each profile, the CEC loss caused by 240C heating is highly correlated with total organic carbon (r=0.99), with the amount of carbon extracted (r=0.98), and fairly well correlated with the amount of iron plus aluminum extracted (r=0.88). The degree of Podzol development, as judged in the field, is related to the loss of CEC caused by heating or extraction, and also to the amounts of carbon, iron, and aluminum extracted. These relationships are used as the basis for proposed quantitative limits that would separate spodic horizons from cambic and other diagnostic horizons.
Effect of Crop Cultures on the Infiltration of Water Into a Chestnut Soil
Authors: Fernandez Benjamin , Wilkinson G. E.
Published: July 2010

Two crop cultures, one consisting of 2 years of corn following a rotation of small grains and corn, the other of 7 years of continuous crested wheatgrass, were selected for a study of the infiltration of water into Morton loam, a Chestnut soil in the Northern Great Plains. Infiltration rates were measured with the Purdue sprinkling infiltrometer in June and August. The equilibrium infiltration rates during the wet run averaged 0.4 inch/hr for corn which was significantly lower than the 1.0‐inch/hr for crested wheatgrass. The effect of dates was not significant. The average aggregate stability index of the surface 8 cm of soil was also significantly lower for the corn. However, the lower aggregate stability under corn had little effect on the absorption of water during the first 30 min. The antecedent moisture level of the soil had its greatest influence on infiltration during the first 30 min. The probability of receiving rains with intensities greater than the infiltration rates is high enough to make Morton loam susceptible to soil erosion under a corn culture.
Variables‐Separable Solution of the Horizontal Flow Equation with Nonconstant Diffusivity
Authors: Swartzendruber Dale
Published: July 2010

Solution of the nonlinear diffusion‐type equation is approached by both an additive form and a product form of separation of variables. The problem considered is the special case of one‐dimensional water absorption by a horizontal, semi‐infinite column of uniform soil initially at a uniform water content, and which from time zero on has a higher constant water content applied and maintained at one end. The additive separation of variables implies boundary conditions for which the water content depends on distance and time. On this basis, it is shown that an equation proposed in the literature, and arrived at by a transformation equivalent to a special case of additive variables‐separation, is not a solution to the problem.

However, the problem is solved by using a product form of separation of variables, which reduces to the equivalent of the Boltzmann transformation by virtue of one boundary condition. Hence, in the light of this approach, the Boltzmann transformation appears as a consequence of the governing partial differential equation and one boundary condition, rather than as an additional assumption in need of separate justification.
The pH Values of Soils Suspended in Dilute Salt Solutions
Authors: Clark J. S.
Published: July 2010

The pH values of dilute solutions and soils were measured with the standard glass‐reference electrode combination and with the glass‐silver, silver chloride pair without liquid junction. At low ionic strengths, the pH values of the soils and solutions determined with the glass‐Ag, AgCl Combination were about 0.1 to 0.2 unit lower than those obtained using the standard reference electrode. With the soils, the differences were observed even when the KCl junction was kept in the clear supernatant liquid. Stirring the solutions and the soil suspensions and increasing the salt concentration decreased the pH values measured with the glass‐reference pair but not with the glass‐halide electrode combination. From these observations it was concluded that pH measurements made at low ionic strengths using the standard reference electrodes with restricted diffusion of KCl were subject to direct liquid junction errors. These liquid junction potentials were distinct from Donnan‐electromotive force (emf) effects caused by interaction of the charged soil particles with the KCl junction. Like the Donnan‐emf effects, they could be reduced by increasing the electrolyte concentration in solution.
Proferential Hydroxyaluminum Interlayering in Montmorillonite and Vermiculite
Authors: Barnhisel R. I. , Rich C. I.
Published: July 2010

The rate of Al diffusion in both montmorillonite and vermiculite was a function of the relative humidity, and the initial saturating cation. In both clay systems, it is proposed that Al‐interlayers were produced in alternate layers giving a regularly interstratified sequence. The clay exhibited 001 reflections integral with a 25A to 27A spacing. These high angstrom spacings were obtained only after the clays had been heated to temperatures of 110 and 300C for montmorillonite and vermiculite, respectively. The sequence is believed to consist of alternating layers, one predominately Al‐saturated and the other Na‐saturated. The Al layers contained enough hydroxy‐Al to provide sufficient stability to these layers to prevent their collapse when the samples were heated at moderate temperatures. The Na layers were either partially or completely dehydrated when heated and these layers collapsed to either 12A or 10A.

The difference in the temperature required to produce the regular interstratification in vermiculite is presumably related to the rapid rehydration of vermiculite samples after the 110C heat treatments.
Applicability of Models to Predict Rates of Cation Movement in Clays
Authors: Gast R. G.
Published: July 2010

Results of electrical conductance and diffusion measurements in dilute bentonite pastes show significant changes in Na+ and Sr2+ ion mobility on increasing solution or clay concentration. Any useful model to predict rates of cation movement in those systems must allow for these changes in mobility. A three‐component model does provide for these changes and appears promising to predict rates of cation movement in systems where the geometry is not affected by varying the electrolyte levels or the nature of the cation species. The use of two‐component models to predict rates of cation movement in such systems requires the capability to predict the mobility of exchangeable cations (those cations on the clay) by some independent measurement or fundamental property of the system. Exchangeable cation mobility did not vary in Na‐ and Sr‐kaolinite systems with increasing electrolyte levels. Two‐component models could be used to predict rates of cation movement in these systems provided the geometry factor and mobility of exchangeable cations is known.
Infiltration and Erosion as Affected by Minimum Tillage for Corn (Zea mays L.)
Authors: Mannering J. V. , Meyer L. D. , Johnson C. B.
Published: July 2010

Minimum tillage for corn substantially increased infiltration and reduced soil erosion during a 5‐year study on a sloping, silt loam soil in Indiana. These results were obtained under high‐intensity, simulated rainfall with rows and tillage parallel to the slope. Infiltration averaged 24% greater and soil loss averaged 34% less from minimum tillage treatments than from conventional treatments. The different forms of minimum tillage tested, including plow‐plant (with and without a trailing harrow) and wheel‐track plant, resulted in about the same amount of erosion control. Erosion comparisons were made on first, third, and fifth year of corn following several years of alfalfa (medicago sativa) orchardgrass (dactylis glomerata) meadow. The relative erosion‐reducing effectiveness of minimum tillage as compared with conventional tillage declined from 44% to 34% to 27% during this period. Destruction of surface crusts by cultivation greatly reduced both soil and water losses throughout the remainder of the crop year. Soil aggregation, organic matter content, and porosity were slightly higher on minimum tillage plots than on conventional plots after 5 years of treatment. Three tons per acre of dry hay used as surface mulch applied after the first cultivation essentially eliminated soil and water losses during the remainder of the crop season. The mulch also effected major reductions in soil and water losses in the succeeding year.
The Characterization of Dry Matter and Nitrogen Accumulation by Loblolly Pine (Pinus taeda L.)
Authors: Switzer G. L. , Nelson L. E. , Smith W. H.
Published: July 2010

Fifty trees, equally distributed to represent five tree developmental stages were sampled in central Mississippi on uplands and bottomlands having average site indices of 65 and 105, respectively. Trees were divided into seven components and the dry matter and total nitrogen contents of each determined. The total dry weight and the N accumulated in a 60‐year old good site stand was ca. 227,000 and 232 lb/acre, respectively, Comparable weights for the poor site are 152,000 and 194 lb. Calculations indicate in pure even‐aged, natural stands on both sites that the dry weight of the foliage, current branches and stembark becomes relatively constant between 20 and 30 years while subsequent increases are chiefly older branches and stemwood. The pattern of N accumulation closely follows canopy development on both sites although in later life a considerable portion is accumulated in the stemwood.
Hysteretic Moisture Characteristics and Hydraulic Conductivities for Glass‐Bead Media
Authors: Topp G. C. , Miller E. E.
Published: July 2010

The hysteretic effects in the moisture characteristics and the hydraulic conductivity characteristics of two different glass‐bead media were measured while unsteady water flow was occurring. A gamma‐ray moisture sensor, a combination of pressure transducers and tensiometers, and a capillary‐tube flux meter were combined with a simple box‐like flow chamber for simultaneous measurement of (i) the degree of saturation, (ii) the water‐phase pressure, and (iii) the hydraulic conductivity. These quantities were recorded through out water‐pressure changes which traversed the main‐branch wetting and drying curves as well as the families of “rewet” and “redry” scanning loops.

Large hysteresis was recorded in the relation of pressure to saturation or to conductivity. The relation of conductivity to saturation showed hysteresis which, though significantly larger than the experimental error, would for most practical purposes be negligible.

The independent domain theory of hysteresis was used to check the relation between the “rewet” and “redry” families of moisture characteristics. By this test the theory was found to be very poorly suited to a description of these media. Two basic approximations of the theory were assumed to be responsible for this lack of applicability.
Chemical Extraction of Potassium from Soils and Micaceous Minerals with Solutions Containing Sodium Tetraphenylboron: IV. Muscovite
Authors: Reed M. G. , Scott A. D.
Published: July 2010

Methods of extracting the interlayer K in micaceous minerals with NaTPB solutions were modified to maximize the extraction of K from muscovite. In the method adopted, 0.500‐g samples were placed in 10 ml of 2n NaCl‐0.2n NaTPB‐0.01m EDTA solution at 25C, and the precipitated K was separated with a boiling 0.5n NH4Cl solution that contained HgCl2. Even with this method, muscovite released its K much slower than did biotite. However, it was possible to remove 96% of the K in <10µ muscovite in 16 weeks. This was also the maximum amont of K that was extracted.
Phytotoxic Substances Extracted from Soil
Authors: Guenzi W. D. , McCalla T. M.
Published: July 2010

Phytotoxic substances were extracted from soil with 0.1m Na4P2O7 and acetone. The ether‐soluble substances from the pyrophosphate extract were separated into acidic, neutral, and basic fractions. Acidic materials exhibited the highest phytotoxicity, followed by basic materials and then by the neutral fraction. The acetone extract of soil was fractionated on an alumina column using a solvent elution series. A number of compounds were isolated by paper chromatography and the majority of these substances were either ninhydrin‐positive or acidic. Three phenolic acids were isolated and identified as vanillic, p‐hydroxybenzoic, and protocatechuic.

Ferulic, p‐coumaric, p‐hydroxybenzoic, vanillic, and syringic acids were extracted with 2n NaOH from plowed and subtilled soil. Larger amounts of ferulic and p‐coumaric acids were found in subtilled soil as compared with the plowed soil. Only traces of these phenolic acids were found with 0.1m sodium pyrophosphate, calcium oxide, 2n HCl, and methanol extracts of soil.
Comparisons of Laboratory and Greenhouse Tests for Nitrogen and Phosphorus Availability in Soils
Authors: Ozus Turgut , Hanway John J.
Published: July 2010

Greenhouse techniques were developed for estimating nutrient availability in soils which would provide standards for comparison of different chemical soil tests. Plants were grown on undried soil samples to which nothing except water was added, but where other nutrients were supplied to the plants. Plant growth and P contents were highly correlated with the results of a chemical soil test. Plant uptake of N during the early period of growth was highly correlated with the initial NO3 content of the soils. Later plant uptake of N was highly correlated with the aerobic and anaerobic rates of N mineralization in the soils, but the relationships were different at different levels of P availability in the soils.
Responses of Different Lines of Soybeans (Glycine max L. Merr.) to High Levels of Phosphorus and Potassium Fertility
Authors: Dunphy E. J. , Kurtz L. T. , Howell R. W.
Published: July 2010

Comparisons were made of the response to fertilizer of many varieties and Plant Introduction lines of soybeans in field experiments at different locations in Illinois over a 3‐year period. At each experiment one‐half the area within each replication received a large application of P and K and the other half remained untreated. Varieties and lines were then planted in random arrangements in each half of each replication. Yields of each variety and line were measured and observations of some morphological characteristics were made. Results were analyzed to learn whether the different soybeans responded differently to the high level of soil fertility.

Some varieties and lines do possess, to a greater degree than others, the ability to respond to high levels of fertility. Other varieties are insensitive to variations in fertility, and yield nearly as well at mediocre fertility levels as on highly fertilized soils. A majority of the lines and varieties tend to respond to a similar degree.

“Ability to respond” was usually exhibited consistently though different years. In a few instances varieties appeared to respond differently in different years but the year‐variety interaction was never statistically significant in this study.

At one location, ratings of several morphological characteristics (e.g. standability) were made and the effect of fertilizer on these ratings was determined for each genotype. While correlation coefficients between pairs of those effects were low, several were statistically significant and suggested some interesting relationships. For example, varieties that responded more to fertilizer were usually the higher‐yielding varieties. Increases in stem length tended to be associated with increased yield response. Varieties that exhibited the most severe potassium‐deficiency symptoms were not usually the ones that gave the greatest yield response to fertilizer.
A New General Soil Map of the United States: A Progress Report
Authors: Gallup Darrell L. , Austin Morris E. , Orvedal Arnold C.
Published: July 2010

Compilation of a new general soil map of the USA is under way. A new map is needed to provide new information accumulated over the past 20 or 30 years, to express our knowledge about soils in terms of the new classification, and to incorporate new ideas in map and legend design that improve interpretation potential. An experimental map, on which most map units are geographic associations of great groups of the new classification, is being compiled on a 1:7,500,000 base. In the legend, map units are grouped under the order, suborder, and great group of their most extensive soils, an organization which permits three levels of generalization. The map will be published in the National Atlas of the USA being prepared by the US Geological Survey.