bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 5. Fixed Ammonium
Authors: Silva J. A. , Bremner J. M.
Published: July 2010

A method of determining fixed ammonium in soils is described. The soil sample is treated with alkaline KOBr solution to remove exchangeable ammonium and organic nitrogen compounds, and the residue is washed with 0.5M KCl and shaken with 5N HF:1N HCl for 24 hr, the ammonium released by the HF‐HCl treatment being determined by steam distilling the soil‐acid mixture with KOH. The KOBr treatment effects almost quantitative removal of organic soil nitrogen under conditions which preclude fixation by soil minerals of ammonium released from soil organic matter by this treatment, and evaluation tests indicate that the procedure used to estimate fixed ammonium in the KOBr‐pretreatment residue is satisfactory. The method is simple and precise, and it has none of the observed defects of previous methods of estimating fixed ammonium in soils. It gives higher values than the Dhariwal‐Stevenson, Bremner, and Mogilevkina methods, and lower values than the Rodrigues and Schachtschabel methods. A modification in which the HF‐HCl treatment is performed at 100C for 30 min is described.
A Modified Procedure for the Determination of Total Boron from Soil Fused with Sodium Carbonate
Authors: Gupta Umesh C.
Published: July 2010

Total boron was extracted by 6N HCl and by 6N H2SO4 from a soil fused with Na2CO3. The amount of boron in the resulting extracts was determined directly. It was found that the H2SO4 extraction of soils interfered with the absorbance of the boron carmine complex resulting in high values of boron. No interferences were encountered with the HCl extracts. Further, the resulting extracts from HCl were easily filtered. The percentage recovery of the added boron from the investigated soils, when extracted by 6N HCl was good and the results were reproducible.

Heating 6N acid solutions for a period of 2 hr on a hot water bath at 100C resulted in no loss of boron. Carmine reagent was found to be stable for at least 18 days when stored in polyethylene bottles at room temperature.
Genesis, Mineralogy and Related Properties of West Indian Soils: I. Bauxitic Soils of Jamaica
Authors: Ahmad N. , Jones Robert L. , Beavers A. H.
Published: July 2010

The red and brown bauxite soils of Jamaica occurring over hard, pure white limestone are strongly aggregated, freely drained soils of almost pure clay texture. They are of low fertility, nitrogen and potassium being very deficient. The red bauxite is deficient in available phosphate but not responsive to phosphorus fertilization. Phosphorus fractionation data show both soils to be adequately supplied with phosphorus. The brown bauxite is much higher than the red in total phosphate and in aluminum‐ and calcium‐bonded forms. Both soils are very high in iron‐bonded phosphate with the red bauxite having a greater percentage of the total phosphate in reductant soluble form. Chemical analysis shows the soils to be very high in Al2O3 content with little or no difference between the two soils. Silica content is very low. Iron is high and virtually all of it is present in dithionite extractable form. No minerals containing potassium seem to be present in the soils. Mineralogical study shows the Al2O3 to be present as gibbsite and boehmite in a ratio of 2:1 for both soils. The soils had less than 10% kaolinite, the brown bauxite being higher. Traces of chlorite were identified in both soils, and traces of montmorillonite were found in the deeper layers of the brown bauxite. Titanium was present as rutile and anatase in the brown bauxite but only as anatase in the red. The red bauxite is richer in goethite. The low content of silicates in the bauxites is associated with a low SiO2 content of the insoluble residue of the limestone and this is evidence for possible genesis of the bauxites from the underlying limestone.
Growth and Nutrient Uptake of Irrigated Young Ponderosa Pine After Fertilizer Treatments
Authors: Tarrant Robert F. , Silen Roy R.
Published: July 2010

Ammonium nitrate and treble superphosphate were applied to irrigated, 7‐year‐old ponderosa pine (Pinus ponderosa Laws.) in a wind break planted on Deschutes sandy loam in central Oregon. Nitrogen was supplied at levels of 0, 200, and 400 lb/acre and P at 0, 100, and 200 lb/acre in a factorial experiment. Fertilizer treatments were repeated two years after initial application.

Over a 6‐year period after first fertilizer treatment, tree growth was stimulated in relation to amount of N applied singly. When N and P were applied together in various combinations, growth was in some cases stimulated and in other cases reduced, according to the combination of the two elements. Foliage N concentration was not affected significantly by any treatment, but when P was applied at the 100‐lb rate, addition of N treatments caused a linear increase in foliage N concentration. With P at 200 lb, addition of N caused a linear decrease in foliage N concentration.

At the conclusion of the study, N content of soils receiving the heaviest N fertilizer application was only about 11% more than that of the controls. However, under heaviest P treatments soil P was more than five times that of unfertilized soils.
Nickel‐Barium Exchange Selectivity Coefficients for Montmorillonite
Authors: McLean G. W. , Pratt P. F. , Page A. L.
Published: July 2010

Nickel‐barium exchange selectivity coefficients were determined for a montmorillonite clay by saturating 0.5‐g samples with 0.04N serial concentrations of NiCl2 and BaCl2. The values for the reaction BaZ + Ni2+ ⇄ Niz + Ba2+ ranged from 0.65 to 0.78, indicating a preferential adsorption of barium.
Determination and Isotope‐Ratio Analysis of Different Forms of Nitrogen in Soils: 6. Mineralizable Nitrogen
Authors: Keeney D. R. , Bremner J. M.
Published: July 2010

An incubation method of estimating mineralizable soil nitrogen which does not require preliminary analyses to determine the amount of water required for incubation and is applicable without modification to soils having widely different textures is described. It is based on the finding that the amount of water required for maximal aerobic mineralization of nitrogen during incubation of soils is practically the same for different soils (ca. 0.6 ml/g of soil) if the soil sample is mixed with three times its weight of 30‐ to 60‐mesh quartz sand before incubation. The method involves determination of the (exchangeable ammonium + nitrate + nitrite)‐N produced when 10 g of soil mixed with 30 g of sand are treated with 6 ml of water and incubated at 30C for 14 days under conditions which ensure adequate aeration without loss of water. It is simple and precise, and evaluation tests indicate that it provides a good index of soil nitrogen availability.
Estimation of Dead‐End Pore Volume in Soils from Transient‐ and Steady‐State Diffusion Coefficients
Authors: Jackson R. D. , Klute A.
Published: July 2010

A means of estimating dead‐end pore volume in porous materials using transient‐ and steady‐state diffusion coefficients is presented. The few available data indicate that dead‐end pore volume in soils is a small percentage of the total pore volume.
Composition of Dilute‐Acid‐Fluoride (Bray P1) Extracts of Illinois Soils
Authors: Tandon H. L. S. , Motto H. L. , Kurtz L. T.
Published: July 2010

The Bray P1 reagent (0.03N NH4F + 0.025N HCl) is widely used to extract “available P” from soils, but few studies have been made to determine the other elements that it removes with P. Illinois soils differing in pH and P fertilization were extracted with the P1 reagent and also separately with its two components, 0.025N HCl and 0.03N NH4F. These extracts were analyzed for P, Al, Fe, Ca, Mg, Mn, and Si. Phosphorus extracted by the P1 reagent or by 0.03N NH4F was not correlated with soil pH or any of the other elements extracted. Combinations of Al with P in the soil, if they existed, could have been masked since the Al extracted by P1 and by 0.03N NH4F were many times greater than the P extracted. Phosphorus removed by 0.025N HCl was positively correlated with soil pH and with the Ca and Mg in the same extracts. From most soils the P1 reagent removed more P than the sum removed separately by 0.03N NH4F and 0.025N HCl. However, the reverse was true for a soil naturally high in calcium. Removal of the “Al‐P” fraction of Chang and Jackson markedly reduced the P removed in a subsequent extraction with the P1 reagent. Also, very little Al was extracted by P1 after the “Al‐P” fraction had been removed.
Cesium Sorption in Relation to Lattice Spacing and Cation Exchange Capacity of Biotite
Authors: Sawhney B. L.
Published: July 2010

Interlayer K from biotite was extracted with sodium tetraphenylboron for varying time intervals. Then, the Cs sorbed from 10‐4N and 10‐6N CsCl solutions by the original biotite and its altered products was determined.

The increased removal of K successively increased the vermiculite component with expanded 14A lattice and a larger CEC and decreased biotite with a collapsed 10A lattice and a smaller CEC. Further, the greater the amount of vermiculite and larger the CEC, the more was the Cs sorbed. Obviously, the expanded component with a larger CEC sorbed more Cs than its collapsed counterpart. These sorptions by mixtures of biotite and vermiculite, thus, do not support the contention that Cs is sorbed selectively by minerals with a 10A lattice spacing.
Kaolinization of Biotite as a Result of Coniferous and Deciduous Seedling Growth
Authors: Spyridakis D. E. , Chesters G. , Wilde S. A.
Published: July 2010

The rhizospheric activity of coniferous and deciduous tree seedlings grown for a period of 13 months in sand cultures containing biotite (50 to 2µ) as the only source of K and Mg, effected the transformation of biotite to kaolinite. The identity of the kaolinite was established by means of X‐ray diffraction and electron microscope analyses. The effectiveness of the seedlings in producing kaolinite from biotite was in the order: white cedar > hemlock > white pine > white spruce > red oak > hard maple [(Thuja occidentalis) > (Tsuga canadensis) > (Pinus strobus L.) > (Picea glauca > (Quercus rubra L. (Q. borealis Mich. x.f.) > (Acer saccharum)]. The conditions prevailing in the cultures accelerated the hydrolytic process and removal of K, Mg, and Fe from biotite and their substitution by H3O causing kaolinization. Electron microscope data revealed the characteristic hexagonal crystals of kaolinite forming on the mica surfaces. Monterey pine (P. radiata) grown in sand cultures converted biotite to vermiculite. The formation of vermiculite rather than kaolinite was attributed to the presence of metal cations in the root remains added to the cultures at the outset of the experiment.
Clonal Differences in Yield Response of Populus deltoides to Nitrogen Fertilization
Authors: Curlin James W.
Published: July 2010

Trees propagated from cuttings of 22 clones of Populus deltoides were grown under unfertilized and nitrogen‐fertilized conditions. Large increases in growth resulted from fertilization. A strong clone × fertilizer interaction was observed for diameter, height, and volume growth. Wood specific gravity was reduced by fertilization but no interaction between clones and fertilizers was noted for that character after 2 years.

The presence of the genotype‐environment interaction indicated that it would be unwise to select eastern cottonwood from a nutritional environment other than the one in which it will ultimately grow. Frequently a clone which performed poorly under unfertilized conditions excelled when fertilized and in several instances the reverse was true. This suggests the possibility that selection can be made specifically for fertilizer response in tree improvement programs. Caution should be exercised when interpreting fertilizer response of experimental populations which might contain genetic bias.
Psychrometric Measurement of Soil Water Potential without Precise Temperature Control
Authors: Rawlins S. L. , Dalton F. N.
Published: July 2010

A theoretical analysis shows that by imposing certain boundary conditions it should be possible to eliminate the major effects of temperature fluctuation on psychrometric measurements of soil water potential. Tests on a psychrometer constructed to meet these boundary conditions were carried out on a soil column in a greenhouse. Although diurnal fluctuation of soil temperature was as great as 5C, water potential was measured with an apparent accuracy of ±0.5 bars throughout two irrigation cycles.
‘A’ Values of Potassium Related to Other Indexes of Soil Potassium Availability
Authors: Nuttall W. F. , Warkentin B. P. , Carter A. L.
Published: July 2010

A technique was developed to measure ‘A’ values of K with oat (Avena sativa) plants grown in the greenhouse and with the radioactive isotope 42K. The isotope 42K has a short half‐life (12.42 ± .03 hours) and was applied to the soil as KCl (approximately 2 mc of 42K/g of 39K) 14 to 18 days after seeding. Plants were harvested to determine initial quantities of K at the time of tagged fertilizer application. Six days later the fertilized plants were harvested and the activity in the plant tissue was counted in a liquid scintillation spectrometer. For 11 soils the total of exchangeable K plus nonexchangeable K accounted for 56% of the variability in K uptake at the time of tracer application, whereas 92% of the variability in ‘A’ values was accounted for by these measurements. Results from the experiments indicated that both amounts of exchangeable and nonexchangable K should be used as availability indexes.
Interstratification in Vermiculite and Biotite Produced by Potassium Sorption: I. Evaluation by Simple X‐ray Diffraction Pattern Inspection
Authors: Rhoades J. D. , Coleman N. T.
Published: July 2010

The formation of mixed‐layer minerals occurred upon potassium sorption by sodium or magnesium vermiculites with a change in the interlayer cation composition from the homoionic state to one of varying K/Na or K/Mg proportions. The type of mixing occurring in the vermiculites, as deduced by examination of X‐ray diffraction patterns, was similar to that expected for regularly interstratified systems. The same conclusion could not be drawn for the Na‐ or Mg‐biotite material. The effect of particle size on this phenomenon is such that the tendency toward regularity of mixing was greater for the 50 to 74µ than for <2µ materials. It was concluded that it is difficult to distinguish regular from random interstratification in the trioctahedral mica minerals due to coincidence of all but the weakest peaks of the two systems.
Infrared Studies of Hydroxy‐Aluminum Interlayer Material
Authors: Weismiller R. A. , Ahlrichs J. L. , White J. L.
Published: July 2010

Differential infrared spectra of films of Al‐montmorillonite matched with films of Al‐montmorillonite with artificially introduced hydroxy‐aluminum interlayers showed the interlayer to give absorption bands at 3,695 cm‐1 and 3,570 cm‐1 of nearly equal intensity. The pleochroism of the 3,695 cm‐1 band indicated an orientation of many of the hydroxyls normal to the oxygen surface of the montmorillonite. The nonpleochroic nature of the 3,570 cm‐1 band indicated an orientation at a moderate angle to the oxygen surface for the balance of the interlayer hydroxyls. A decrease in frequency from 3,695 cm‐1 to 3,670 cm‐1 and an increase from 3,570 cm‐1 to 3,600 cm‐1 upon drying can be explained by dehydration and by a closer association of the high frequency hydroxyls (3,695cm‐1) with the oxygen surface of the clay. A single ring, six aluminum, polymer lying planar in the interlayer position would be expected to have the structural requirements to satisfy the observations in the 1.5:1 OH/Al interlayer system.
Influence of Slope on Size and Distribution of Fields in Iowa
Authors: Runge E. C. A. , Riecken F. F.
Published: July 2010

The objective of this investigation was to determine the percentage of the land in Iowa and in the major soil associations within Iowa that would fall into various field sizes when slope criteria were the only factors determining field size. A method was developed to determine the percentage of land which would fall into various field sizes (10–160 acres or ca. 4–65 hectares). Slope and acreage of individual soil mapping delineations for selected fields within each 1/4‐section (ca. 65 hectares) tract was the input in this study. The soil map data by 1/4‐sections represents a 2% sample of Iowa and consists of approximately 4,500 individual 160‐acre tracts. For this study, 100 1/4‐section tracts were selected in each of the four replicates. The number of 1/4‐sections included in each replicate for each soil association was the same as the percentage of that soil association in Iowa.

The frequency of occurrence of different size fields meeting six sets of slope criteria are given with 5 and 10% confidence intervals for Iowa, and without confidence intervals for soil associations within Iowa. As field size increased and as more level fields were evaluated, the percentage of land in Iowa meeting the slope criteria decreased. Most of the large nearly‐level fields are in soil associations in northwest and north‐central Iowa, and in the Missouri and Mississippi river bottomlands. The within 1/4‐section variance was less than that between 1/4‐sections.
A Simplified Method for Preparation of Soil Thin Sections
Authors: Gile Leland H.
Published: July 2010

A simplified method for thin section preparation requires a relatively small amount of materials and time. Heating is required only twice, no evacuation is necessary, and only one impregnating solution is used. A ratio of 3.5 parts of acetone to 1 part of Laminac resin is used for impregnation, with Lupersol DDM as a catalyst. Impregnated chips and cover glasses are attached to slides with clamps, using epoxy as a cementing agent. The method has satisfactorily impregnated both noncalcareous and highly calcareous soil materials ranging in texture from clay to loamy sand, with and without gravel.
Relationships Among Electrochemical Properties, Type of Colloid and Adsorbed Cations of Soil and Mineral Colloidal Suspensions
Authors: Rhoads F. M. , Nash V. E.
Published: July 2010

Potentiometric cation activities, electrophoretic mobilities and specific conductance at variable frequencies were determined on suspensions of five reference clay minerals and five soil clays. The objectives of this work are: (i) to determine the relationship between clay mineralogy and specific conductance with a variable frequency power source, (ii) to determine the interrelationship among the various electrochemical measurements, and (iii) to study the effect of different exchangeable cations on the electrochemical properties.

Montmorillonitic minerals with a charge deficiency in the octahedral layer showed the greatest change in specific conductance with increasing frequency. Vermiculite, on the other hand, showed less evidence of a change in conductance with frequency; illite showed no change. This was taken to indicate that a greater proportion of the exchangeable cations on montmorillonite was in the Stern layer whereas the cations on the higher surface charge density clays were distributed between the Gouy and the chemisorbed layer.

A Stern layer on the montmorillonite minerals developed to a greater extent for monovalent cations than divalent. The divalent cations were apparently located between the unit layers of the mineral and did not conduct electric current even at high frequencies.
The Significance of Apatite Inclusions in Soil Phosphorus Studies
Authors: Syers J. K. , Williams J. D. H. , Campbell A. S. , Walker T. W.
Published: July 2010

Apatite inclusions have been identified in several primary minerals, and their abundance and morphology have been described. A comparison of several methods used for the determination of total P in soils showed that Na2CO3 fusion is the most reliable method for samples which contain apatite inclusions and that the effectiveness of extraction was usually in the order: Na2CO3 fusion > HF digestion > HClO4 digestion > N H2SO4 extraction following ignition. Included apatite was identified using a petrological microscope in residues after digestion with 60% HClO4. This form was also extracted much more slowly by 0.5N HCl than was nonincluded apatite. Included apatite resistant to attack by 1N HCl was determined as “residual inorganic P” in fractionation studies on weakly weathered materials, and the influence of fineness of grinding on the ratio of “acid‐extractable Ca‐P” to residual inorganic P indicated the likely dimensions of the inclusions in different minerals.
Influence of Cations on Flocculation of Clay Minerals by Microbial Metabolites as Determined by the Electrical Sensing Zone Particle Analyzer
Authors: Santoro T. , Stotzky G.
Published: July 2010

Flocculation of clay minerals by microbial metabolites was determined by measuring changes in particle‐size distribution. No floculation occurred when clay and metabolite mixtures were analyzed in sodium metaphosphate as the suspending electrolyte. When the mixtures were analyzed in electrolytes containing the chloride salt of the cation to which montmorillonite was made homoionic, all metabolites caused flocculation in the presence of trivalent cations, some with divalent cations, but none with monovalent cations. Similar results were obtained with purified rhizobial polysaccharides, which, however, also flocculated kaolinite homoionic to Na. The degree of flocculation of the clays differed with the source of the metabolites. A nonionic polyacrylamide (Separan) flocculated both montmorillonite and kaolinite, regardless of the type of cation present. The possible implications of these results in the aggregation of soil by microorganisms are discussed.
Synthesis and Transformation of Phenolic Compounds by Epicoccum nigrum in Relation to Humic Acid Formation
Authors: Haider K. , Martin J. P.
Published: July 2010

During the growth of the fungus Epicocium nigrum in glucose‐asparagine medium, 2,4‐dihydroxy‐6‐methylbenzoic acid(orsellinic acid) and 2‐methyl‐3,5‐dihydroxybenzoic acid (cresorsellinic acid) are synthesized. These are altered by decarboxylation, by introduction of additional hydroxyl groups, by oxidation of methyl groups, and by further decarboxylation to form over 20 phenols. Some of the phenols are trihydroxy benzene compounds such as 2,4,5‐trihydroxy toluene, which are autoxidizable at pH values of 6 or above. These compounds, after autoxidation to quinones, couple with resorcinol‐type phenols or with o‐diphenols. Nonresorcinol type phenols added to the culture solution are altered by introduction of hydroxyl groups, by demethoxylation, and by oxidative splitting of the side chain. The benzene ring is essentially resistant to degradation by the fungus. Amino acid compounds present in the culture medium or formed by the organism are either linked into oxidative polymers of the phenols or are deaminated by action of some of the oxidized phenols. “Humic acid” formation commences at about pH 6 in the nutrient solution and is associated with the disappearance of the phenols. Carbon‐14 studies indicated that the phenol ring of added compounds takes part in polymer formation. With time, mixtures of the same phenols synthesized by the fungus and peptides or amino acids will react to give “humic acid”‐type compounds, However, evidence for weak phenoloxidase activity in the fungus mycelium was found. During autolysis this phenolase may be released into the medium and could further an oxidative polymerization of the phenols and their autoxidation products.
Relative Absorption of Strontium and Calcium by Certain Algae
Authors: Fuller Wallace H. , Hardcastle James E.
Published: July 2010

The relative uptake of strontium and calcium was compared, using seven different species of algae (A. falcolus var. aci cularis, Scenedesmus, sp., Pediastrum sp., Sphaerocystis sp., Phormidium sp., Nostoc sd., and Anabaena sp.,) isolated from fresh water and arid land. Uptake always fovored calcium over strontium when the two elements were present in nutrient media together. Strontium was absorbed in addition to the calcium requirement. With Scenedemus sp., however, strontium actually appeared to compete with calcium.
An Acid‐Free Vanadate‐Molybdate Reagent for the Determination of Total Phosphorus in Soils
Authors: Tandon H. L. S. , Cescas M. P. , Tyner E. H.
Published: July 2010

An acid‐free vanadate‐molybdate reagent was developed for the spectrophotometric determination of P in HClO4 digests of soils. The optimum acidity in the analysis is derived from the residual acidity of the HClO4 digest of soils. A comparative study of the proposed reagent with a commonly used molybdenum‐blue method on ten widely different soils indicated that the proposed method gave highly reproducible results and was not affected by high amounts of Fe3+ which is invariably present in soils. In rare cases chromium interference can be serious because of the similarity of the color of the chromate ion to that of the molybdivanadophosphoric complex. For soils low in chromium, chromate interference can be removed by volatilization as chromyl chloride during the digestion. The modified reagent greatly simplifies the determination of total P and is admirably suited for automated analysis.
Interaction of Limestone Particle Size and Phosphorus on the Control of Soil Acidity
Authors: Barrows Harold L. , Taylor Alan W. , Simpson Elmer C.
Published: July 2010

Various size fractions of limestone and calcite were equilibrated in a Leon fine sand previously treated with varying rates of phosphorus. The efficiency of 42‐ to 48‐mesh liming material was reduced 1.1, 1.6, and 5.8%, respectively, by the addition of 25, 50, and 150 ppm P. The same levels of P reduced the efficiency of 12‐ to 14‐mesh material 2.2, 3.6, and 8.5%. Material finer than 80‐mesh was not affected. The reduced efficiencies were attributed to the formation of surface coatings of phosphatic material. The susceptibility of a given soil to coat liming material may be assessed by measurements of hydrogen ion (H+) and phosphate (H2PO4‐) potentials.
Potassium Fixation by Amorphous Aluminosilica Gels
Authors: van Reeuwijk L. P. , de Villiers J. M.
Published: July 2010

Synthetic aluminosilica gels fixed potassium in varying amounts against replacement by common alkali and alkaline earth cations; the larger the solvated size of the replacing cation the greater was the amount of K retained. Replacing power thus followed the lyotropic series NH4 > Na > Ba > Ca > Mg. The amounts of K fixed against exchange by a particular ion increased with total cation‐exchange capacity (in turn dependent on gel composition) and with the pH value at which K‐saturation originally took place. A marked increase in capacity to fix K was shown to result from drying the gels prior to K‐saturation. Drying presumably increased the rigidity of channels in the gel structure which restrict the passage of larger hydrated cations and which, as with zeolites, are responsible for the fixation phenomenon. For xerogels, wet‐ and dry‐fixation measurements yielded results of the same order of magnitude.
Microbially Induced Phytotoxicity in Stubble‐Mulched Soil
Authors: Norstadt Fred A. , McCalla T. M.
Published: July 2010

Incubations of subtilled soil amended with wheat straw (Triticum aestivum L.) caused the development of a phytotoxic soil. Studies of the toxic soil and wheat residues revealed increased Penicillium urticae Bainier numbers and formation of patulin, a potent phytotoxic substance. Microbial activity, as measured by plate counts and O2 consumption, increased as phytotoxicity increased. Inoculation of incubated, amended, non‐sterile subtilled soil with P. urticae B. caused the greatest proliferation of the fungus and patulin formation at the time intervals corresponding to highest phytotoxicity. The plant symptoms and the inhibition of Trichoderma sp. during incubations of the subtilled soil were indications of patulin formation. Associated microorganisms during incubation of subtilled soil amended with wheat straw quite likely caused the development of a substrate favorable to P. urticae B. growth and patulin formation.
Genesis and Relative Weathering Intensity Studies in Three Semiarid Soils
Authors: Smith B. R. , Buol S. W.
Published: July 2010

The role of clay illuviation and clay formation in situ in the development of argillic horizons in arid and semiarid regions has been the subject of some controversy among pedologists. This study included two profiles with argillic horizons and one profile without an argillic horizon.

Thin section examinations revealed very few illuviation cutans and some stress cutans. Fine clay (< 0.2µ) / coarse clay (2‐0.2µ) ratios increased in the argillic horizon of the two Haplargid profiles. Relative weathering intensities within the three profiles were estimated from CaO/ZrO2 molecular ratios obtained by X‐ray spectrographic analysis of the silt fraction. These molecular ratios indicate that maximum weathering has occurred at or near the soil surface and that weathering has decreased with depth in all of the profiles studied. It is concluded that clay formation in situ is not solely responsible for the development of an argillic horizon in arid and semiarid soils. More likely, both clay formation in situ and enrichment by illuviation of fine clay (<0.2µ) are responsible for the argillic horizons in soils of arid and semiarid regions.
Determination of Soil Aluminum by Fluorescence
Authors: Cook M. G.
Published: July 2010

A procedure was developed for soil Al determination based on the fluorescence of the Al salt of 8‐hydroxyquinoline in chloroform. The method was effective in determining both exchangeable and total Al. Highly accurate results were obtained on samples varying widely in Al content.
Self‐Diffusion of Tritiated Water in Montmorillonite and Kaolinite Clay
Authors: Phillips R. E. , Brown D. A.
Published: July 2010

The quick‐freeze technique of measuring diffusion coefficients of ions in clays and soils was adapted to the measurement of self‐diffusion coefficients of tritiated water in clays. The self‐diffusion coefficients of tritiated water were approximately equal in the kaolinite and montmorillonite clays. The water contents, oven‐dry weight basis, used for montmorillonite were 125.0, 118.5, 100.0, and 87.0%; the water contents used for kaolinite were 60.5, 55.0, 43.5, and 39.0%. The calculated average number of water layers on each mineral surface ranged from 3.5 to 5.5 for montmorillonite and from 17 to 26 for kaolinite. The self‐diffusion coefficients in creased in a linear manner as the average number of water layers present on each mineral surface increased; a slightly different rate of increase was obtained for each of the two clays. The lack of difference of the diffusion coefficients in the two clays could not be explained on the basis of charge density of the clays nor was a difference in viscosity a plausible explanation. A longer path length of the diffusing water molecules in the kaolinite and a smaller relative mobility of the diffusing water molecules in the montmorillonite is given as a possible explanation.
Retention of Boron by Layer Silicates, Sesquoxides, and Soil Materials: II. Sesquioxides
Authors: Sims J. R. , Bingham F. T.
Published: July 2010

Boron retention by hydroxy iron and aluminum materials was found to be pH dependent with maximum retention occurring in the alkaline range. The hydroxy aluminum materials retained B in amounts that were an order of magnitude greater than the amounts retained by the hydroxy iron materials. Boron retention by these materials was significantly reduced by aging on a steam bath prior to being treated with B.

Iron and aluminum were precipitated from solutions in the presence of B in application of the “mole ratio” method of determining the formulas of complexes. Evidence was obtained indicating Fe(III) or Al(III) and B were precipitated in stoichiometric proportions. Considering these precipitated forms as “solid complexes” with the general formula, MXn, a greater variety of complexes was found in the Al(III) systems than in the Fe(III) systems. In the Fe(III)‐B systems, values of n for the most part were ≤1.0; in the Al(III)‐B systems, values of n were ≥1.0.

Samples of similar constitution to those used in the “mole ratio” study were prepared for each metal at three pH levels. The amount of B combined in the precipitate was determined as a function of aging. The amount of B combined in the precipitate of the pH 6 samples remained relatively unchanged throughout the course of the 42‐day aging period whereas the amount of B combined in the pH 9, 10, and 11 samples decreased with time. Since the observed decreases in the amounts of B combined in the precipitates were limited to the pH 9, 10, and 11 samples, it was concluded that the ready source of hydroxyl ion in these suspensions promoted hydrolysis of the hydroxy iron and aluminum precipitates, resulting in expulsion of B from the precipitates probably as borate ions.
Influence of pH, Calcium, Iron, and Aluminum on the Uptake of Radiophosphorus by Cranberry Plants
Authors: Medappa K. C. , Dana M. N.
Published: July 2010

Radiophosphorus accumulation by the cranberry (Vaccinium macrocarpon L.) was studied in relation to pH, Ca, Fe, and Al in nutrient solutions. There was no direct effect of H+ activity on radiophosphorus (32P) accumulation by the plants between pH 3 and 7. However, with the medium at pH 8, phosphorus (P) accumulation was depressed. From media at pH 3 to 7, the plants were capable of accumulating comparable amounts even at low levels of 32P activity. Calcium concentrations from 0 to 750 ppm and Fe concentrations from 0 to 50 ppm had no appreciable effect on the uptake of 32P. Phosphorus accumulation tended to increase with the addition of 1.2 ppm Al but decreased with 12 ppm or more. This decrease in P accumulation in the presence of Al was more pronounced at pH 6.5 than at pH 3.5 or 4.5. It is suggested that at the highest pH value aluminum phosphate precipitated both inside and outside the root tissue and thereby impaired P accumulation in the shoots.
Tolerance of Soybean Varieties To High Levels of Phosphorus Fertilizer
Authors: Dunphy E. J. , Meissen M. E. , Fulcher C. E. , Kurtz L. T.
Published: July 2010

A soybean (Glycine Max. L. Merr.) variety classified as “tolerant” to very high levels of P fertility was paired and compared with a “very sensitive” variety in field experiments involving seven levels of P fertilizer (0, 16, 49, 147, 442, 1,330, and 3,980 kg P/ha). These experiments were carried out at two locations with three pairs of varieties over a 3‐year period, and irrigation was included as a variable at one location for 2 years.

Yields of “tolerant” and “very sensitive” varieties were similar at the lower P levels, although responses by the “very sensitive” variety sometimes appeared slightly larger.

Yields of all varieties were depressed by the largest P application, but the yield of the “tolerant” member of each pair was always greater than that of the “very sensitive” variety. At this largest P addition, the average yield of the “very sensitive” varieties was only two‐thirds of that of the “tolerant” varieties. These results were consistent with the “tolerance classification” that had been made previously by Howell and Bernard (4) from the behavior of the varieties in solution culture under greenhouse conditions.

Irrigation resulted in marked increases in yields of both “tolerant” and “very sensitive” varieties, but no interactions were found among irrigation, varieties, and levels of P fertilizer.

The observed relation between P‐fertilizer additions and yield of soybeans indicated that the addition of the P‐fertilizer in geometric rather than arithmetic increments would often be advantageous for such experiments involving a wide range of fertilizer additions.
Organic Soils on the Lower Coastal Plain of North Carolina
Authors: Dolman J. D. , Buol S. W.
Published: July 2010

The organic deposits on the lower Coastal Plain of North Carolina form a blanket of variable thickness over a mineral landscape which was dissected during the Wisconsin glacial period. The characteristics of the soils developed in the organic deposits show a distinct relationship to their position over the pre‐peat landscape.

The soils found over the higher parts of the pre‐peat landscape are chiefly classified as Leptists and mineral soils with histic epipedons. They consist of debris from a mixed swamp forest vegetation, have brown to black colors, are well aerated, friable, and show considerable faunal activity.

The soils found over the lower parts of the pre‐peat land scape are chiefly classified as Saprists. They are formed from remains of Nyssa‐Taxodium swamp vegetation, have reddishbrown to dark reddish‐brown colors, are poorly aerated and are structureless. When wet they are paste‐like but upon drying they become hard, often irreversibly so. They are more acid than the shallow organic soils, and very little faunal activity is in evidence.

Translocation of organic matter can be observed in the shallow organic soil but presently not in the deep area. The organic matter in the deep soil appears to be more resistant to oxidation than that in the shallow organic soil.
Availability of Boron in Various Boronated Fertilizers
Authors: Mortvedt J. J.
Published: July 2010

Rates of B dissolution from various boronated fertilizer granules in soil increased with the level of water‐soluble B in the fertilizers. Effectiveness of B for alfalfa (Medicago sativa L.) was similar whether partially dehydrated borax (Na2B4O7 · 5H2O) was either mixed alone with the soil or incorporated with various fertilizers and applied to the soil in a greenhouse experiment. Uptake of B increased with rate of applied B, but forage yields were not affected. Plant uptake of B correlated well with a combination of the level of water‐soluble B in the fertilizers and the number of granules applied, but not with either parameter alone. This suggests that dissolution of B from boronated fertilizers and distribution in the soil are important for optimum application of B with macronutrient fertilizers.

Forage yields and P uptake by corn (Zea mays L.) and alfalfa were increased with rate of P applied as concentrated superphosphate (CSP) in another greenhouse test. The inclusion of various concentrations of B as borax in CSP granules did not affect yields or P uptake by either crop, indicating that borax can be incorporated into this fertilizer without impairing its effectiveness as a P source.
Clay Retention, Activities, and Excised Root Uptake of Ions in Bentonite Suspensions and Dialyzates
Authors: Snyder G. H. , Reicosky D. C. , McLean E. O. , Franklin R. E.
Published: July 2010

Suspensions of bentonite clay saturated with varying Ca and K or Rb ratios and containing several concentrations of CaCl2 or KCl were membrane equilibrated with equal volumes of water. Activities and concentrations of Ca and K or Rb, and Cl ions in both suspension and dialyzate phases were determined with electrode and radioactive tracer techniques. The “suspension effect” (greater activity of cations and lesser activity of anions in the suspension than in the dialyzate phase) increased with increased K saturation (decreased Ca saturation) and with decreased electrolyte concentrations. Permanent charge cation exchange sites appeared to contribute most to the suspension effect, while the pH‐dependent charges favored hydrolysis of the metallic cations and thus tended to mask the suspension effect.

A given concentration of electrolyte was many times more effective in causing changes in cation retention by the clay phase when the clay was predominantly saturated with Ca rather than with Rb. Higher retention of cations at high Rb saturations generally paralleled the electrode‐measured activities and excised root uptake (corn and soybeans) of cations. Addition of 0.2 S of CaCl2 decreased the differences in cationic activities between phases and generally eliminated significant differences in uptake between phases.
Mineral‐Weathering Correction for Estimating the Sodium Hazard of Irrigation Waters
Authors: Rhoades J. D.
Published: July 2010

An equation previously proposed by Bower (2, 4) for evaluating the Na hazard of irrigation waters has been modified to include the effect of soil‐mineral weathering on the changes that occur in the SAR values of waters applied to soils. The modification involves the incorporation of a coefficient which reduces the predicted soil drainage‐water SAR values by various amounts, depending upon the mineral properties of the soil and the leaching regime used. The value of the coefficient required in the equation can be determined by simple laboratory procedures. The modified equation was tested on a calcareous soil by comparing the SAR values predicted from the equation with values actually obtained in a controlled lysimeter experiment. The applicability of the equation is supported by the excellent correspondence obtained between the calculated and observed SAR values.
Self‐Diffusion of Phosphorus in Clays and Soils: II. The Effect of pH
Authors: Place G. A. , Phillips R. E. , Brown D. A.
Published: July 2010

The effect of pH on the self‐diffusion coefficient of 32P was measured in kaolinite, montmorillonite, illite, Dundee silt loam, and Sharkey clay. Six fractions of soil phosphorus were evaluated and related to the effect of pH on the self‐diffusion coefficients of 32P by multiple linear regression analysis. The free iron oxide content was determined in each medium and related to the variation in self‐diffusion coefficients between media.

The self‐diffusion coefficients were significantly affected by pH in all media. A multiple regression analysis for individual clays and soils where self‐diffusion was the dependent variable and water soluble‐P, Al‐P, Fe‐P, occluded Fe‐ and Al‐P, and Ca‐P were the independent variables revealed that water soluble P in kaolinite was positively correlated (R2 = 0.673) and occluded Al‐P in montmorillonite was negatively correlated (R2 = 0.402). There were no significant terms in the other media. The magnitude of the self‐diffusion coefficients between media was kaolinite > montmorillonite > Dundee silt loam > illite > Sharkey clay. When the self‐diffusion coefficients and phosphorus fractions were averaged over all pH values, self‐diffusion increased as the water soluble‐ and Al‐P concentrations increased and the Fe‐P and free ion oxide contents decreased.
Determination of the Solubility Product of Soil Constitutents Such as Gypsum
Authors: Rance Joan M. , Davey B. G.
Published: July 2010

The solubility product of gypsum at 20C was calculated using a converging cyclic procedure which involved the use of a published value for the dissociation constant of gypsum, an experimentally determined value for total Ca concentration, and the second approximation of the Debye‐Hückel equation.

Total Ca concentration of filtered saturated extracts was determined using atomic absorption spectroscopy.

From this method the solubility product of CaSO4 at 20C was found to be 2.46 × 10‐5 and 32.1% of total soluble Ca was found to be present as ion pairs.
Detachment of Soil Particles in Simulated Rainfall
Authors: Mazurak Andrew P. , Mosher Peter N.
Published: July 2010

Soil materials were fractionated into 20 separates ranging from 4,760µ to < 2µ in diameter. These separates were packed into splash‐cups and exposed to simulated rainfall intensities of 2 to 12 cm/hr. Raindrops were 5.1 mm in diameter and fell 11.33 m onto the surface of soil materials. Soil particles detached from the surface by the raindrops were oven‐dried and weighted.

The amount of detached soil particles from surfaces of all separates was linearly related to simulated rainfall intensity. Linearity was significant at the 0.01 level of probability, except for the coarsest and finest separates. Slope of the line is used to characterize the susceptibility of soil materials to detachment from the surface by raindrops. The slope is measured as milligrams of particles per cm3 of water hitting the surface of soil materials.

Detachment of soil particles exposed to simulated rainfall increased from 2.2 mg/cm3 of water for separates 4,760–3,360µ in diameter to a maximum amount of 288 mg/cm3 of water for separates 210–149µ and 149–105µ in diameter. Then, the amount of detached particles decreased with decreasing diameter of particles. Detachment for < 2µ diameter particles was 11 mg/cm3 of water.

High‐speed movies showed that splash of raindrops from surfaces of separates > 105µ in diameter consisted of much smaller water drops than from separates < 105µ in diameter. Splash from the surfaces of separates < 105µ in diameter exhibited a crown effect and then broke into smaller drops.
Particle Size Analysis of Soils Compared by Sodium Metaphosphate and Sodium Carbonate Dispersion Methods
Authors: Dixon J. B. , McCracken R. J. , Peele T. C. , Rich C. I.
Published: July 2010

Particle size data obtained by the Na2CO3‐centrifuge method can be used for soils free of carbonates as a substitute for those obtained by the “standard” NaPO3‐pipette method. Dispersion by NaPO3 and Na2CO3 boiling was essentially the same for 13 soil samples. Differences of a few percent clay were common between soil samples analyzed by the NaPO3‐pipette and Na2CO3‐centrifuge methods.
Quantitative Analysis for Nonionic Surfactants in Soil Leachates
Authors: Valoras N. , Letey J.
Published: July 2010

Two methods for quantitatively analyzing nonionic surfactant concentration in soil leachates were investigated. A colorimetric technique was found to produce good results for several nonionic surfactants (including two which have been marketed primarily for soil use) without interference from extraneous materials extracted from the soil in the leachate. A turbidity technique was found to apply for surfactants diluted in distilled water, but was not useful for the analysis of surfactant in soil leachates.
Reactivity of Montmorillonite Surfaces with Weak Organic Bases
Authors: Swoboda Allen R. , Kunze G. W.
Published: July 2010

The adsorption of organic amines and pyridines was used to study the reactivity of magnesium and calcium‐saturated montmorillonite surfaces. The ability of clays to chemisorb organic bases of different pkb values was used as a measure of the acid strength of their surface. Chemisorption and physical adsorption of the organics were differentiated by infrared analysis of the organic‐clay complex. Nontronite and Otay bentonite are the most reactive of the montmorillonites studied, being able to chemisorb bases with pkb values greater than 11.4. The active sites on Wyoming bentonite were found to be heterogeneous with respect to acid strength. The majority of the sites reacted with organic bases with pkb values of 8.8 and below, but chemisorbed only a small amount of aniline and m‐chloroaniline which have pkb values of 9.4 and 10.5, respectively. Hectorite chemisorb bases with pkb values of 8.8 and below but did not chemisorb a base with a pkb of 9.4.
The Movement of Zinc to Plant Roots
Authors: Wilkinson H. F. , Loneragan J. F. , Quirk J. P.
Published: July 2010

Previous workers have classified nutrients on the basis of their movement patterns to plant roots, as shown by autoradiographic techniques, together with calculations using soil and plant nutrient levels and transpiration ratios. Autoradiographs of 65Zn depletion were similar to those shown by other workers for 32P. No difference was observed in zinc levels in tops or roots when transpiration ratios were trebled (from 49 ml/g to 173 ml/g), indicating that zinc absorption is not dependent on mass flow of solution to the roots.