bluuebunny/crossref_metadata_2025 huggingface dataset:
Genesis of Argillic Horizons in Celina and Morley Soils of Western Ohio
Authors: Smeck Neil E. , Wilding L. P. , Holowaychuk N.
Published: July 2010

Variation in the mode and magnitude of development of argillic horizons in Celina and Morley soils of western Ohio was studied by physical, chemical, mineralogical, and morphological means to explain the difference in Bt/C clay ratios between these Hapludalfs. Although Celina may have formed on a somewhat older land surface than Morley, parent material must be considered the chief factor responsible for differences in genesis of sola since other soil‐forming factors are quite similar. Both soils are derived from Wisconsin‐age till deposits but, in this study, till associated with Celina soils has a mean clay content of near 23% and a calcium carbonate equivalent of near 40% whereas till underlying Morley soils has near 33 and 25%, respectively. Mean maximum clay content in Bt horizons is near 41% for Celina and near 50%; for Morley which yields a Bt/C clay ratio of 1.8 and 1.5, respectively.

Carbonate particle‐size distribution in C horizons indicates very coarse sand, coarse sand, and coarse silt generally have the highest calcium carbonate equivalents whereas coarse clay contains <10% and fine clay <1% carbonates. Reconstruction of gains and losses of clay in Bt horizons were calculated both on a weight and volume basis. These results indicate that most of the difference in Bt/C clay ratios is due to carbonate dilution of clay in C horizons and that the remaining difference can be attributed to a larger clay gain in Celina Bt horizons.

Other differences in genesis of argillic horizons in these soils are indicated by mineralogical and micromorphological data. Clays with a 17.7A d‐spacing when glycolated which is indicative of montmorillonite were found in Celina argillic horizons but these clays were not apparent in Morley argillic horizons. Thin section studies suggest that upper Bt horizons of Celina soils are actively undergoing degradation and the meager quantity of fine clay gain is due to montmorillonite and vermiculite being diagenetically transformed from illite in situ. Illuviation of clay accounts for the majority of the large clay gain in the lower Bt horizons of Celina soils. The clay gain in Bt horizons of the Morley soils is accounted for by illuviation of clay from overlying horizons and in situ formation of vermiculite. Both processes account for similar quantities of clay gain but together do not form as large a clay increase in the Bt horizons of Morley as Celina soils.
Two North Carolina Coastal Plain Catenas: II. Micromorphology, Composition, and Fragipan Genesis
Authors: Nettleton W. D. , McCracken R. J. , Daniels R. B.
Published: July 2010

A study of two soil catenas of different age in the middle Coastal Plain of North Carolina compares the micromorphology and composition of fragipan and nonfragipan soils. The two catenas differ principally in that one has bisequal sola and fragipans in the less well‐drained members, whereas the other has thinner sola with well‐developed argillic horizons but no fragipans. Presence of papules, as well as high packing density and proximity indices, indicate that collapse of the soil matrix has caused the high bulk density of the fragipan horizons. The relatively low amounts of clay in fragipan horizons is believed to be a result of the greater susceptibility of clay to translocation and possibly destruction during reduction and removal of the iron. Translocation of this clay is confirmed by the marked increase of illuvial clay bodies, primarily illuviation cutans and grain argillians, in B′2t horizons below the fragipan (A′2gx). Relative to their clay content, fragipan horizons contain more fine clay with infrared absorption bands in the 2.9µ H‐bonded OH region than do nonfragipan horizons. This clay lacks definite crystalline form and is thought to be amorphous. Stable at lower temperatures, the infrared absorption band at 2.9µ is lost along with the fragipan brittleness at 300C. Though of low free iron content, this clay has a high pH dependent charge. Under the low pH conditions (4.5–5.0) found in fragipan horizons, this clay may develop strong hydrogen bonds with quartz and other silicates.
The Effect of Soil‐Mineral Weathering on the Sodium Hazard of Irrigation Waters
Authors: Rhoades J. D. , Krueger D. B. , Reed M. J.
Published: July 2010

The extent to which the release of solutes from soil‐mineral weathering processes changes the composition of applied irrigation waters has been evaluated for six arid‐land soils. Soil samples were packed in plexiglas permeameters and pretreated to remove readily soluble organic matter, to minimize subsequent microbial activity, and to equilibrate the soil exchange‐complexes with the irrigation waters. Soil solutions were displaced from the nearly saturated columns and analyzed at biweekly intervals until a steady composition was attained. The effluent solutions were 3 to 5 meq/liter higher in total salt content than the applied waters. The gains were accounted for primarily by Ca + Mg and HCO3 ions. The net effect of these changes in solution compositions was a 30 to 90% reduction in the SAR values of the applied solutions. The SAR reductions were greatest for the waters of lower salt concentrations, but were significant even for waters containing as much as 15 to 20 meq of salt per liter. This phenomenon reduces the Na hazard expected with certain irrigation waters, and should be considered in water‐quality evaluation.
The Driving Force on an Ion in the Absorption Process
Authors: Olsen R. A.
Published: July 2010

When identical root samples are placed in an exchanger suspension of low electrolyte content and in the equilibrium dialyzate we find that the rate of absorption of Rb+ is equal from each medium. If the two media are carefully maintained at equilibrium conditions, the equality in rate of absorption is observed for a period of many hours. The results support the hypotheses that the driving force on an ion is the electrochemical potential gradient extending at right angles through the periphery of the root and that ion absorption is a relatively simple diffusion process.
Age and Comparative Development of Desert Soils at the Gardner Spring Radiocarbon Site, New Mexico
Authors: Gile L. H. , Hawley J. W.
Published: July 2010

Radiocarbon ages have been obtained from seven buried charcoal horizons in a desert area of southern New Mexico. Several deposits of highly calcareous alluvium range in age from less than 1,100 to somewhat greater than 5,000 years and are therefore of Recent age. Pleistocene deposits much older than 5,000 years also occur. Pleistocene soils of adjacent topographic highs were a major source of the Recent sediments. Evidence in this area indicates that the present climate is warmer and drier than the Pleistocene pluvial climates. This change to a drier and warmer climate could have decreased the vegetative cover in places and started strong erosion of Pleistocene soils in these areas.

The dated charcoal also establishes a maximum, and in some instances a minimum age for several soils formed in the deposits. With increasing age of soil during Recent time, the progression of soil development appears to have been marked by development of an A horizon, destruction of thin sedimentary strata, slight accumulation of carbonate, development of structure in materials of sufficiently fine texture, and, with continued carbonate accumulation, development of a weak calcic horizon. In contrast, soils of Pleistocene age can have distinct argillic horizons and strong horizons of carbonate accumulation. It is postulated that the wetter climates of Pleistocene pluvials, associated with greater vegetative cover and landscape stability, were required for development of argillic horizons in these highly calcareous parent materials.
Rupture Parameters of Soil Aggregates
Authors: Rogowski A. S. , Moldenhauer W. C. , Kirkham Don
Published: July 2010

Rupture stress values of air‐dry aggregates of various sizes taken from nine surface soils containing from 7 to 53% clay are given as load in dynes per unit area. Corresponding rupture strain values are given as change in polar diameter at rupture per unit length of polar diameter. The rupture modulus defined as the stress/strain ratio is also listed. The values depend on the assumption that aggregates approximate spheres. Earlier work and visual observation show that this assumption is valid for 2‐ to 8‐mm aggregates. Experimental stress‐strain curves indicate that Hooke's law is valid up to rupture. Values of rupture stress, rupture strain and rupture modulus were found to be significantly correlated with percent clay, percent organic carbon, aggregate bulk density, aggregate size distribution and soil erodibility.
Influence of Soil Structure on Water Relations in Low Humic Latosols: II. Water Movement
Authors: Sharma M. L. , Uehara G.
Published: July 2010

Experiments were carried out to study the effect of two aspects of structure, macrofabric (arrangement of peds) and microfabric (arrangement of primary particles within the ped), on water movement. Two latosolic soils of nearly similar composition and varying greatly in soil fabric were used. Capillary conductivity of the soils and their water‐stable aggregates were obtained. The results showed that the effect of macrofabric on water movement was more pronounced in the lowtension range (0–0.2 bar). Identical flow rates were obtained for the same size water stable aggregates of both soils, suggesting that intra‐ped pores did not significantly contribute to water flow in this tension range. It was suggested, however, that microfabric might influence fluid flow properties in the high tension range.
Isotopic Exchange Characteristics of Aluminum‐ and Iron‐bound Fractions of Soil Phosphorus
Authors: Tandon H. L. S. , Kurtz L. T.
Published: July 2010

The source of most of the isotopically exchangeable P in widely different soils was found to be in the Al‐ and Fe‐P fractions. The relative contribution of Fe‐P to exchangeable P was greater at longer exchange periods, showing that Fe‐P had more slowly‐exchangeable components than Al‐P. The rate of exchange of Al‐ and Fe‐P varied from 28 to 162 ppm/hr and 22 to 72 ppm/hr, respectively, in the first half‐hour and was in no case greater than 2 ppm/hr after 24 hours of exchange. Ratio of specific activities of Al‐ or Fe‐P were used to compare the surface activities of the P fractions. The term “Relative Activity Number” (ratio of specific activities of Al‐ to Fe‐P in a soil) is proposed as an index of the relative activity of Al‐ and Fe‐P. RAN for soils studied varied from 1.11 to 2.80 showing that Al‐P was 1.11 to 2.80 times as active as Fe‐P. RAN in soils which had received P was smaller than RAN in untreated soils showing greater exchangeability of the reaction products in the Fe‐P form. In a few soils as much as ½ to ⅔ of Al‐ and Fe‐P was not exchanged in 147 hours. Thus, a considerable proportion of these P fractions is relatively “inactive.”.
Effect of Chelating Agents on the Availability of 54Mn Following its Addition as Carrier‐Free 54Mn to Three Different Soils
Authors: Wallace A. , Mueller R. T.
Published: July 2010

Carrier‐free 54Mn was mixed into samples of three different soils and allowed to equilibrate for several days. The soils were Yolo loam (slightly acid), Hacienda loam (calcareous), and Dinuba fine sandy loam (neutral). Bush bean (Phaseolus vulgaris var. ‘Improved Tendergreen’) and corn (Zea mays var. ‘Golden Cross bantam’) were grown in the soils with the presence and absence of various chelating agents. Yields and 54Mn and total Mn were determined in the leaves and specific activities were calculated. After cropping, the control soils were assayed first for water soluble, then exchangeable 54Mn and Mn, and then easily reducible or 10‐3M EDDHA, EDTA, DTPA, and NTA soluble 54Mn and Mn. The 54Mn appeared to differentially label various forms of Mn in the soil. Bush bean leaves contained more 54Mn and Mn per plant than did corn. The specific activities of the 54Mn in bush bean leaves were more like those for the easily reducible Mn than for other Mn forms for the three different soils but the specific activities in the corn, in contrast, were more nearly like those in the exchangeable Mn in the soils. DTPA tended to increase the amounts of both 54Mn and Mn in plants with the Yolo and Dinuba soils with concommitant decreasing specific activity of Mn. With corn DTPA apparently added easily reducible Mn to the pool of available Mn. EDTA tended to increase uptake of the soluble and exchangeable Mn by the plants. NTA and EDDHA had little effect.
Properties and Mineralogy of Soils Derived from Argillized Tuff in the Mount Carmel Region, Israel
Authors: Singer A.
Published: July 2010

Two representative profiles of simple horizonation derived from argillized tuff material in the Mount Carmel region of Israel, near the Mediterranean sea coast, were investigated in the field and laboratory. A shallow profile developed in situ on a partly argillized tuff. Calcium carbonate has accumulated in larger quantities in the solum than in the C. This is attributed to release of Ca by weathering of primary minerals in the solum. The main clay mineral in the parent material is an iron‐rich saponite, similar to cardenite. In the clay fraction from the upper soil horizons a second, dioctahedral montmorillonite appears also, accompanied by small quantities of kaolinite and halloysite. In a second profile, developed on alluvium derived from the alteration products of a slightly altered black tuff, calcium carbonate accumulation is greater in the C than in the solum. The <2 µ alteration product of the tuff rock, as well as the clay from the soil, consists chiefly of an iron‐rich saponite. In the clay fraction from the upper horizon of the profile the saponite is accompanied by a second, dioctahedral montmorillonite. In both profiles a large part of the clay fraction is in sand and silt‐sized aggregates which are very difficult to disperse. Soil genesis in both profiles seems essentially to have accomplished a slight accumulation of organic matter and organization of structural soil units, accumulation and some translocation of calcium carbonate and formation of a dioctahedral montmorillonite and some kaolinite and halloysite. The absence of a marked contamination of the sand and silt fractions by aeolian quartz indicates youthfulness of these soils.
Studies of Clay Skins in a Cecil (Typic Hapludult) Soil: I. Composition and Genesis
Authors: Khalifa E. M. , Buol S. W.
Published: July 2010

Continuous clay skins are found on ped faces, in pores, and around root channels in the B22t horizon of Cecil soils in North Carolina. Thicker, discontinuous clay skins are also observed along vertical pores in the Cl horizon. Compared to the whole peds from the B22t horizon the clay skins contain more clay, fine clay (<0.2µ), total iron, free iron, Al2O3, K2O, P2O5, and total nitrogen; less silica and gibbsite than the whole soil peds. The fine clay fractions (<0.2µ) of the A2 horizon and the clay skins of the B22t horizon are similar, both being finely divided and poorly crystalline compared to the fine clay from the whole peds of the B22t horizon and the clay skins in the Cl horizon.
Agricultural Use of Synthetic Metal Chelates
Authors: Brown J. C.
Published: July 2010

Synthetic metal chelates have been used effectively to make iron available to plants in soils. Agricultural use of chelates has been influenced by cost of the materials, their stability, pH of the soil, and the kind of crop. There is competition between chelating agents and between roots and chelating agents, for nutrient elements. Differential uptake of the metal and ligand by the plant has been demonstrated. The use of synthetic metal chelates in agriculture appears as a stop‐gap measure until a more permanent solution is obtained for some of our micronutrient problems. Genetic variants as factors affecting plant nutrition may provide the permanence sought by providing a plant adapted to a particular soil.
Micronutrient Cation Complexes in Soil Solution: IV. The Chemical State of Manganese in Soil Solution
Authors: Geering H. R. , Hodgson J. F. , Sdano Caroline
Published: July 2010

Soil solutions from several areas of the US were analyzed by atomic absorption for total Mn and by resin exchange for percent Mn complexed. Values for the latter (84%–99%) in soil solution from the A horizon were intermediate to those previously reported for Zn and Cu. Soil solution from a New York forest soil at pH 7 contained 13 ppm Mn, of which 93% was complexed. Spectrophotometric and polarographic methods were developed to determine the oxidation state of Mn in this soil solution. Both methods indicated the Mn in solution was present in the +2 oxidation state. The presence of such large concentrations of Mn2+ in a soil solution of a neutral soil was still less than that predicted from measured values of the Eh of the soil solution and the Mn2+/MnO2 half‐cell potential. Soil microorganisms oxidized and precipitated Mn2+, presumably as MnO2, but the presence of the neutral soil solution that contained 13 ppm Mn partially inhibited this precipitation.
Soil Respiratory Activity and Organic Matter Depletion in an Arid Nevada Soil
Authors: Lyda S. D. , Robinson G. D.
Published: July 2010

Incorporation of mature crop residues of alfalfa (Medicago sativa), oat (Avena sativa), and sudan (Sorghum vulgare) into a fine sandy loam soil in southern Nevada stimulated the soil respiratory activity. A close correlation was observed between respiration rate and organic matter content; both decreased steadily over a 6‐month test period.

Four mature crop residues (alfalfa, cotton (Gossypium hirsutum), oat, and sudan) were added to the same soil type in laboratory tests at 1, 2, 3, and 4% (weight/weight). Respiratory activity of these soils was followed for 10 weeks at 2‐week intervals. A maximum activity was noted at the first 2‐week period for the 2, 3, and 4% additions of all four residues.

The respiration rate was proportional to the residue concentration but the increments were not additive. A linear relationship was noted when the reciprocal of the rate was plotted against the reciprocal of the residue concentration, similar to that of a first‐order reaction during the period of maximum activity. It was suggested that a given soil could become saturated with organic matter and reach a maximum respiratory activity; other factors would become rate limiting.
Noteworthy Features of Uruguayan Soils
Authors: Troeh Frederick R.
Published: July 2010

Uruguay has an undulating landscape dominated by Pradera (Prairie) soils with thick, black, fertile A horizons. These soils have strong textural profiles but are only moderately deep (about 80 cm average), have high base saturations, and generally have Cca horizons. There is a typical soil catena that includes the Pradera soils along with Grumosoles and Plano‐soles. This catena occurs on a variety of parent materials in various parts of Uruguay.
Use of Metal Lathe for Making Thin Sections of Silty and Clayey Soils
Authors: Miller D. E.
Published: July 2010

A procedure is described for using a metal lathe in preparing thin sections of soil clods. The procedure allows rapid and uniform reduction of sample thickness before the final polishing.
Lead Accumulation in Soils Near Highways in the Twin Cities Metropolitan Area
Authors: Singer M. J. , Hanson L.
Published: July 2010

The soil adjacent to 12 highways in the Minneapolis‐St. Paul metropolitan area had lead accumulations in the range of 128 to 700 ppm. The lead concentrations found were related to traffic volume and distance from the highway.
Bias Error in Yield Functions as Influenced by Treatment Design and Postulated Model
Authors: Cady F. B. , Laird R. J.
Published: July 2010

Bias error occurs when the fitted or postulated model is not equal to the true functional relationship between the dependent variable and the independent variable(s). The concept of bias error is developed and the effect of various factors on magnitude of the bias error studied. The factors included in an empirical study are spacing and number of fertilizer levels and selection of the postulated model. The choice of a postulated model, a factor not under the control of the experimenter during the planning stages of an experiment, shows the largest influence on bias error. The selection of the postulated model is discussed and suggestions for the control of bias and variance error in response surface experimentation are given.
Opal Phytoliths in Bouteloua Eriopoda Torr. Roots and Soils
Authors: Pease D. S. , Anderson J. U.
Published: July 2010

Identification of phytoliths from Bouteloua eriopoda Torr. (black grama) roots was based on repetitive size and shape, low density, acid insolubility, and lack of crystallinity. Refractive index, and contents of water and SiO2 support identification as opal. These distinctive rectangular phytoliths were the most commonly observed form in the A horizons of several soils and paleosols.
A Disposable Aerator for Radioactive Hydroponic Culture
Authors: Wieland P. A. T. , Romney E. M.
Published: July 2010

An aerator for use with radioactive hydroponic media can be constructed with hypodermic needles and rubber or plastic tubing. The system described is inexpensive and adaptable to fit almost any size or configuration of an experiment. It can be disposed of easily in accordance with laboratory health and safety regulations.
Soil‐Water Movement in Response to Imposed Temperature Gradients
Authors: Cassel D. K. , Nielsen D. R. , Biggar J. W.
Published: July 2010

Redistribution of soil water within insulated, uniformly packed, horizontal samples of unsaturated Columbia fine sandy loam at several soil‐water contents was studied in response to imposed temperature gradients ranging from 0.5 to 1.0C/cm. Soil bulk density and initial, transient, and final soil‐water‐content distributions were determined each 0.5‐cm along the column by gamma‐radiation attenuation. Initial, transient, and final soil temperature distributions were monitored by glass‐encased thermistors at 2‐cm intervals—both at the center and 0.3 cm from the column wall. Apparent thermal and isothermal soil‐water diffusivity values were calculated using transient water content data. The observed net water flux was found to increase with decreasing water content throughout the 0.077–0.274 cm3/cm3 range. For Columbia soil at 0.077 cm3/cm3 the observed mean net water flux across 1‐cm sections of the soil showed acceptable agreement with that predicted by the theory of Philip and deVries; Fick's law and the modified Taylor‐Cary irreversible thermodynamic equation both underpredicted the observed fluxes.
Applied Nitrogen Losses in Relation to Oxygen Status of Soils
Authors: Meek B. D. , Grass L. B. , MacKenzie A. J.
Published: July 2010

The decrease in soil nitrate nitrogen as related to redox potential was studied in the laboratory and in the field in Imperial Valley, Calif.

Partial anaerobic conditions were induced in laboratory flasks containing an atmosphere of 21% oxygen by adjusting the soil‐water ratio. When the water content of a soil having a water saturation percentage of 48% was increased to 44.5% or above, large losses of N2 gas occurred both with and without addition of organic matter. Significant denitrification coincided with a decrease in the redox potential (Eh).

Measurement of redox potential and nitrate concentrations of ground water sampled at various depths in an irrigated field indicated that nitrate concentration was high near the surface but decreased at depths approaching the water table. The diminishing nitrate concentration and redox potential, with depth, indicate that some nitrates were reduced to nitrogen gas before they reached the water table.

Only 1.5% of the 280 kg N/hectare applied to a cotton crop (Gossypium hirsutum L.) was discharged in the tile effluent during the growing season. Denitrification in the soil profile apparently reduced the amount of nitrate reaching the tile drainage system.
Evaluating the Use of Na+, Ca2+, and Divalent Cation Electrodes in Some Soil Extracting Solutions
Authors: El‐Swaify S. A. , Gazdar M. N.
Published: July 2010

The performances of sodium activity, calcium activity, and divalent cation activity electrodes were determined and compared with predicted theoretical responses in unbuffered systems and in buffered systems at concentrations of 0.2 m, 0.5 m, and 1.0 m. In support of previous findings on a less selective sodium electrode, results show that the Na‐electrode exhibits a response which is nearly Nernstian, allowing good estimates of Na+ ion activities in soil extracts. In contrast, the usefulness of the calcium and divalent‐electrodes in buffered systems (and subsequent usefulness for determining exchangeable ions) was found to be limited particularly at high levels of total salt concentration. Although better response was observed for these two electrodes in unbuffered systems, the determination of Ca2+ and Mg2+ in water‐soil extracts by their combined use is limited by the apparent reversibility of the calcium electrode to Mg2+ ions present in calcium‐magnesium salt mixtures.
Reactions of 144Ce in Solution and Suspensions of Soil Humie Acid and Bentonite
Authors: Brown R. E. , Franklin R. E. , Miller R. H.
Published: July 2010

A study was made of the formation of radiocolloids by 144Ce and the adsorption of Ce by equilibrated suspensions of humic acid, bentonite clay, and a mixture of these two colloids saturated with either Ca or K and H. The availability of Ce in these suspensions was measured using excised roots. Ionic strength, Ce concentration, and pH were critical factors affecting the equilibrium between radiocolloidal and monomeric Ce. As ionic strength and Ce concentration decrease and as pH increases the equilibrium is shifted towards the radiocolloidal form of Ce. At pH 6.5 and ionic strength 10‐3 about 90% of the Ce in a solution is in the radiocolloidal form. A multiple regression equation was presented which showed the effects of pH, ionic strength, and Ce concentration on the formation of radiocolloidal Ce in salt solutions. Humic acid adsorbed much greater amounts of 144Ce and restricted uptake by barley and soybean roots more than did bentonite in the Ca‐H saturated system. However, humic acid and bentonite adsorbed similar amounts of 144Ce in the K‐H saturated systems. Mixing bentonite and humic acid produced a synergistic‐type effect in regard to Ce adsorption. It was proposed that the strong bonding of Ce by Ca‐humic acid and humic acid‐bentonite mixtures resulted from a more favorable orientation of the humic acid molecule for chelation of Ce.
Solubility of Calcium Carbonate Precipitated in Aqueous Solutions of Magnesium and Sulfate Salts
Authors: Doner H. E. , Pratt P. F.
Published: July 2010

Calcium carbonates were precipitated in the presence of various salts at controlled CO2 partial pressures. Solubilities of the precipitates were compared with that of calcite and the precipitates were subjected to X‐ray diffraction for the detection of crystalline products and in some cases analyzed for coprecipitated Mg. In NaCl solutions, the solubility of the carbonate was that of calcite. In MgCl2 solutions, the solubility of the precipitate was higher than that of calcite, both calcite and aragonite were detected and Mg was coprecipitated in the solid phase. In solutions of Na2SO4, the solubility of the precipitate was higher than in the case of the MgCl2 solutions and both calcite and vaterite were detected. In solutions of MgSO4, the solubility of the precipitate was intermediate between that of the MgCl2 solutions and the Na2SO4 solutions. The solubility product of CaCO3 seemed to be related mainly to the nature of the solid phase.
Decomposition of 14C‐Labeled Cell Wall and Cytoplasmic Fractions from Hyaline and Melanic Fungi
Authors: Hurst H. M. , Wagner G. H.
Published: July 2010

A hyaline fungus, Aspergillus niger, and an unnamed melanic fungus isolated from a soil sclerotium were grown on 14C glucose, fractionated into cell wall and cytoplasmic components, and the fractions analyzed for C, H, N, OCH3, and specific activity. The cell wall fraction from the melanic fungus was higher in C and OCH3 content than that from the hyaline organism. The fractions were incorporated into soil samples and 14CO2 evolved was determined during 6 months. The rate of decomposition for cell wall material of both organisms was initially lower than that for cytoplasmic material. The hyaline cell wall decomposed at a relatively steady rate for a prolonged period, and after 6 months 70% of the C in this fraction had been lost as CO2 compared with 62% of the C in the cytoplasmic fraction. Cell wall and cytoplasmic fractions of the melanic species were strongly pigmented and resistant to decomposition with 35% and 48% of the C in these respective fractions evolved as CO2. The decomposition of complete, non‐fractionated tissue of additional fungi was also studied. Hyaline organisms (Penicillium sp., Schizophyllum commune, Polystictus versicolor, Lenzites sp.) had a lower C content and underwent rapid decomposition in comparison with melanic organisms (Mycoleptodiscus terrestris, Cladosporium sp., Cenococcum graniforme, Mycelium radicis‐atrovirens, Macrophomina phaseoli).
Selenium Concentrations in Alfalfa from Several Sources Applied to a Low Selenium, Alkaline Soil
Authors: Carter D. L. , Brown M. J. , Robbins C. W.
Published: July 2010

Two laboratory‐prepared ferric hydroxy bi‐selenites and CuSeO3 applied to Portneuf silt loam in the field provided slowly available Se to alfalfa, resulting in Se concentration adequate but nontoxic for livestock. These materials have potential as Se fertilizers at low application rates. The ferric hydroxy bi‐selenites offer little or no advantage over CuSeO3. Se from BaSeO4 alone, BaSeO4‐BaSO4 mixtures, and CuSeO4 was absorbed by alfalfa in concentrations toxic to livestock. A small fraction of applied elemental Se was available immediately after application, providing adequate Se to alfalfa for livestock. The remaining elemental Se was rather inert, and supplies only slightly more Se to alfalfa than did the untreated soil the year following application.
Soil Properties Affecting the Sorption of Atmospheric Ammonia
Authors: Hanawalt Ronald B.
Published: July 2010

At controlled atmospheric‐level ammonia concentrations, ammonia sorption from the atmosphere was weakly correlated with increasing cation exchange capacity and percent clay. Alteration of organic matter content and soil acidity produced only slight changes in sorption rates. These data indicate that lack of bonding sites per se does not limit the sorption rate. In air dry soil the major portion of the sorption occurs in the uppermost 0.5 cm. Sorption rates were closely related to increasing air permeability and moisture content. Since atmospheric ammonia concentration, air velocity across the soil surface, and temperature also strongly influence sorption rates, it is concluded that sorption of atmospheric ammonia by soils is primarily governed by those factors which effect the rate of supply of ammonia to the soil surface and the fraction of the ammonia molecules which are actually captured.
A Plinthaquult of the Aripo Savannas, North Trinidad: I. Properties of the Soil and Chemical Composition of the Natural Vegetation
Authors: Ahmad N. , Jones Robert L.
Published: July 2010

Aripo Fine Sand (Plinthaquult) occupies depressed topography in a region in North Trinidad where rainfall is over 250 cm annually; consequently, the area is submerged periodically in the wet season. The profile consists of a surface albic horizon of 25 cm consisting of bleached silt to fine sand with little organic matter; this is underlain by an argillic horizon with characteristic red and yellow mottling. On exposure, the mottled areas harden irreversibly to nodules. The profile is very strongly acid with very low base saturation. Exchangeable Al is correspondingly high. The albic layer has 0.4% free Fe2O3 in contrast to over 12 times more in the underlying mottled clay layers. Total P is lower than 80 ppm for the whole profile; only the ochreous exterior of mottles have higher P contents. Except in the bleached layer, Al‐P is almost absent and Ca‐P is absent throughout the profile. Forms of P associated with Fe make up the bulk of the total P in the soil. Truog's reagent extracted only 2 ppm P in the bleached layers and just traces in the clay enriched part of the profile.

The flora of the area consists of short, coarse, tufted grasses, sedges, herbs, shrubs, and insectivorous and parasitic plants. Dominant plant species were analyzed for total and insoluble ash, N, P, K, Ca, Mg, S, Fe, and Al. Compared to levels of these nutrients present in rice (Oryza sativa L. var. Indica) and sweet potato (Impomoea batatas L. var. 049) grown under favorable conditions, all species of the vegetation had very low amounts of plant nutrients. The greatest difference occurred for P, K and S. All the species were high in Fe content but values fluctuated and only in the Gramineae was there any consistency. Many of the species, especially the Melastomaceae, were very high in Al. Soil and plant analysis indicated a soil of extremely low fertility status which was also reflected in the poorness of the vegetation.
A Method for Detecting and Estimating Hydrogen Sulfide in Flooded Soil
Authors: Ford H. W. , Calvert D. V.
Published: July 2010

A 60‐ml sorption cell utilizing 0.5 mil PVC membranes permeable to H2S is described. NaOH is used as the sorbing solution. The cell is capable of detecting H2S in soil zones containing < 0.1 ppm in groundwater over short and prolonged periods of anaerobic flooding under conditions of a fluctuating water table.
Evaluation of Atomic Absorption Methods for Determinations of Aluminum, Iron, and Silicon in Clay and Soil Extracts
Authors: Yuan T. L. , Breland H. L.
Published: July 2010

Atomic absorption methods for Al, Fe, and Si determinations were evaluated in clay and soil extracts obtained with 1N NH4OAc (pH 4.8), 0.1N HCl, 0.2M (NH4)2C2O4 (pH 3.0), 0.5N NaOH, and buffered Na2S2O4. The evaluation was made either by correlating the results with those of chemical methods or by calculating the percentage recovery of added Al, Fe, or Si from the extracts. Highly significant correlations and regressions were obtained between the atomic absorption and colorimetric methods for NH4OAc‐ and HCl‐extractable Al and Fe in soils, dithionite‐extractable Fe in clays, NaOH‐extractable Al in soils and clays, and NaOH‐extractable Si in clays. Recoveries of added Al, Fe, and Si from oxalate, dithionite, and dilute alkali media were successful except that the recovery of Fe in soil extracts exceeded 110% in most cases. The presence of a natural humic acid “Leonardite” did not affect the atomic absorption analyses of Al and Si. However, the Fe results were high as was found in soil extracts, indicating organic matter interference in the determination of Fe by this technique. Removal of humic acid by precipitation reduced the Fe but not Al recovery. The coefficients of variation for 10 determinations were below 3% for all three elements with the exceptions of Si at concentrations below 15 ppm and Fe below 2 ppm. Some difficulties were encountered with the oxalate and dithionite as extractants.
Exchangeable Potassium and its Selectivity by Soils as Quantity‐Intensity Parameters for Soil Potassium
Authors: Rezk A. I. , Amer Fathi
Published: July 2010

Significance of K selectivity by soils, as revealed by the Gapon exchange selectivity coefficient, in improving exchangeable K as an availability index was tested on 12 UAR alluvial and desert soils under the high intensity cropping of a Neubauer experiment. Supply of K to plants decreased as selectivity increased and the selectivity coefficient, k, was used to correct exchangeable K, K̄, for differences in selectivity among soils. The ratio K̄/k, proved superior to exchangeable K alone for assessing K supply and accounted for as much as 95.3% of the variation in K uptake by barley plant during 24 days of growth. At variance with exchangeable K and the selectivity coefficient, their ratio K̄/k was found independent of the method of extraction and may prove to be a characteristic soil property defining the quantity‐intensity aspects of soil K supply. For soil testing purposes, the product of potassium‐adsorption ratio and cation‐exchange capacity may offer a simple substitute for the K̄/k ratio in soils having Ca and Mg as the dominant exchangeable cations.
Soil Structure Evaluation With Audiofrequency Vibrations
Authors: Rickman Ron W.
Published: July 2010

Young's moduli for soils measured with a vibrational technique varied with soil aggregate size, water content, texture, sensor‐to‐sample contact, and column handling. The magnitude of a Young's modulus varied from 107 dynes/cm2 (147 psi) for nearly saturated columns to over 109 dynes/cm2 for an airdried, Na‐saturated silt. The accuracy of the moduli measurements is in the order of 15% to 20%. The measured values compare favorably with others previously reported in the literature for undisturbed and reworked soil samples. The range of measured soil moduli, the repeatability of the measurements, the lack of restriction on sample size and the nondestructive nature of the technique indicate that this procedure may provide a useful measure for soil structure evaluation.
An Alkaline Oxidation Method for Determination of Total Sulfur in Soils
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

A rapid and precise method of determining total sulfur in soils is described. The soil sample is heated with alkaline sodium hypobromite solution to oxidize soil sulfur compounds to sulfate, and the sulfate thus formed is reduced to hydrogen sulfide by a modified Johnson‐Nishita procedure and determined colorimetrically as methylene blue. The method gives quantitative results with pure organic and inorganic sulfur compounds, including amino acids, sulfonic acids, organic sulfates, sulfoxides, thioureas, sulfates, sulfites, sulfides, and elemental sulfur. It gives quantitative recovery of organic and inorganic sulfur added to soils and soil extracts, and its results with soils agree closely with those obtained by other methods proposed for total sulfur analysis of soils.
Effect of EDTA on the Self‐Diffusion of Zinc in Aqueous Solution and in Soil
Authors: Elgawhary S. M. , Lindsay W. L. , Kemper W. D.
Published: July 2010

Self‐diffusion coefficients for Zn and ZnEDTA (zinc ethylenediaminetetraacetic acid) were determined in aqueous solution and in soil. Those in solution were estimated from diffusion measurements in agar‐agar gel and were found to be 8.8 × 10‐6 cm2 sec‐1 for Zn and 6.8 × 10‐6 cm2 sec‐1 for ZnEDTA. The apparent diffusion coefficient of Zn in soil increased from 0.36 × 10‐9 cm2 sec‐1 to 3.0 × 10‐9 cm2 sec‐1 with addition of 1.53 × 10‐8 mole of EDTA/g soil and to 9.0 × 10‐9 cm2 sec‐1 with addition of 1.53 × 10‐8 mole of ZnEDTA/g soil. The true diffusion coefficient Dp of Zn in soil was fairly constant at different levels of EDTA, averaging 1.81 × 10‐7 cm2 sec‐1.

Addition of EDTA to soils increased the diffusion of Zn; this increase was explained by the transformation of the solid phase soil Zn into soluble ZnEDTA complexes, thereby increasing the concentration gradient of total diffusible Zn. Chelating agents were shown to play an important role in overcoming the rate‐limiting steps of solution and diffusion which are largely responsible for the movement of micronutrient cations in soils.
Surface Soil Properties of Black Walnut Sites in Relationship to Wood Color
Authors: Maeglin Robert R. , Nelson Neil D.
Published: July 2010

Various soils that supported black walnut (Juglans nigra L.) growth in Indiana and Missouri were analyzed for surface pH, organic matter, available P, exchangeable K, Ca, Mg, total N, silt plus clay content, cation‐exchange capacity (CEC), and depth to mottling or to impervious layer. Quantitative color values (luminance, dominant wavelength, purity) of heartwood of walnut trees grown on these soils were determined by reflectance spectroscopy. The soil properties analyzed were moderate to high for most soils studied. A few soils were found low in available P, silt plus clay content, and organic matter. Regression analyses indicated that variations in soil fertility were correlated with difference in wood color between individual sample trees. The range of observed site quality was rather limited, however, poorer sites showed a tendency toward darker, redder heartwood (lower luminance, higher dominant wavelength). Available P, exchangeable K, Ca, Mg, total N, and pH were found to be most important in relation to color variation.
Further Characterization of Iron Uptake in Two Genotypes of Corn
Authors: Brown J. C. , Ambler J. E.
Published: July 2010

Two genotypes of corn, (Zea mays L.) homozygous yellow stripe ys1/ys1 (Fe‐inefficient) and Pa 54 (Fe‐efficient), were grown in nutrient solution with two levels of CaCO3 using two plant populations. The nutrient solution and plant population were varied to evaluate and compare the two genotypes relative to modifications in their growth medium favorable to Fe transport. Plant factors recognized as favoring Fe transport were (i) ability of roots to lower the pH of their growth medium, (ii) efflux of material by the root that reduces Fe3+ to Fe2+, (iii) increase of citrate in root sap, and (iv) decrease of P in root sap. The Fe‐efficient Pa 54 corn was more efficient than the yellow stripe ys1 in all of the above factors and transported more Fe to leaves than ys1. Once the iron requirement of the plant had been satisfied, the activity of the factors favoring Fe transport diminished and less Fe was taken up by the plant.
Growth and Manganese Uptake by Potatoes as Related to Liming and Acidity of Fertilizer Bands
Authors: White R. P. , Doll E. C. , Melton J. R.
Published: July 2010

The effects of liming and of the acidity of fertilizer bands on the growth and manganese uptake by Norland and Sebago potatoes (Solanum tuberosum L.) were determined on an acid sandy soil in a greenhouse experiment. Four levels of two sources of lime were established and four additional unlimed treatments consisted of: a) no supplements to the fertilizer band, or the addition b) of Al, c) of Mn, or d) of both Al and Mn in the fertilizer band. On all treatments, the equivalent of 1,000 pp2m of a 5‐20‐20 fertilizer was banded. Changes in soil pH and the pH in the fertilizer bands during the growing period were determined by direct contact pH measurements made through access tubes.

Symptoms of Mn toxicity (chlorosis and black specks on the stems and undersides of the leaves followed by death of the lower leaves) were observed on those plants grown on the unlimed soils, and on those containing very high levels of Mn. When the soil was limed to pH 6.5 or above, Mn levels in the plants were markedly decreased and the toxicity symptoms disappeared. Additions of Al to the fertilizer band markedly lowered band pH but had little effect on plant Mn content. Additions of Mn to the band did not affect band pH, and increased plant Mn only slightly. The Norland variety was less tolerant of high Mn levels than was the Sebago variety. The uptake of Mn by the potato plants in this experiment was related to soil pH rather than to the acidity of the fertilizer band.
Distribution of Macro‐ and Micronutrients in Soil Profiles Developed on Lithosequences and under Biosequences in Northern Greece
Authors: Apostolakis Costas G. , Douka Catherine E.
Published: July 2010

The status and the distribution of the macro‐ and certain of the micronutrients in selected soil profiles developed on different parent materials such as granite, quartz diorite, dacite, and marble and under varying cover such as spruce (Picea excelsa L.), scotch pine (Pinus silvestris L.), beech (Fagus silvatica L.), and grasses were investigated.

The results presented in a series of graphic illustrations indicate a distinct tendency for an accumulation of the nutrient supply in the uppermost horizons of the studied profiles.

The nutrient level is influenced by the initial capital of the elements and the alteration to which it has been subjected during soil development processes.

Interactions between the biotic and the edaphic parameters affect the distribution of the nutrients within the profiles.
Variations in Tension Lysimeter Leachate Volumes
Authors: Cochran P. H. , Marion Giles M. , Leaf Albert L.
Published: July 2010

Leachate volumes collected with tension plate lysimeters placed in a glacial outwash soil and maintained at a fixed tension varied from 1.9–629.9% of the total water applied through rainfall and/or irrigation. The amounts of K passing through plates at depths of 152 cm ranged from 0.02–86.1% of that applied at the surface. These differences were attributed to several factors including (i) nonuniform application of water, (ii) large differences in soil moisture retention and flow properties for individual strata, and (iii) irregularity of soil strata arrangement at different locations within the study area. Lateral flow to plate surfaces can result in large overestimates of the nutrient flux at a given soil depth.
Sulfur Uptake by Corn as Influenced by Ammonium and Nitrate Nitrogen
Authors: Rehm G. W. , Caldwell A. C.
Published: July 2010

The effect of NH4 and NO3 ions on S uptake by corn (Zea mays L.) from a starter fertilizer was studied with the use of 15N and 35S. When both the N and S were applied as a starter, the uptake of fertilizer S was significantly increased when NH4 instead of NO3 was used as the N source. This effect was observed in young plants through 4 weeks of age. More N was absorbed by the corn plant when NH4 rather than NO3 was supplied as the N source. The N source, however, had no significant effect on the total S, SO4‐S or total N content of the tissue and the corn yield.
Manganese Movement from Fertilizer Granules in Various Soils
Authors: Mortvedt J. J. , Giordano P. M.
Published: July 2010

Movement of Mn in acid Hartsells fsl (pH 5.1) from fertilizer granules containing 2% Mn as 54Mn‐labeled MnSO4 was in the order: KCl = NH4NO3 [AN] > soil (no carrier) = concentrated superphosphate [CSP] = NH4H2PO4 [MAP] ≫ (NH4)2HPO4 [DAP] = (NH4)3HP2O7 [TPP] = ammonium polyphosphate [APP]. In limed Hartsells soil (pH 7.6) Mn movement was less from granules of all fertilizers, but the order remained the same.

Movement of Mn applied in soil or MAP granules was greater in Spencer sil (pH 4.7) than in five other soils with higher pH levels. Application of Mn with MAP resulted in decreased Mn movement in all soils except Houghton muck. Little or no movement of Mn occurred when MnSO4 was applied with TPP to any of these soils. Reduced movement may have been due to formation of reaction products of low solubility which reduced the concentration gradient of soluble Mn in the soil near the granule site.

Percentage recoveries of applied Mn from the soil immediately adjacent to the granule sites by H2O, neutral 1N NH4OAc, and neutral 1N NH4OAc containing 0.2% hydroquinone showed little difference for Mn applied alone or with granular AN, KCl, CSP, or MAP. However, the recoveries of Mn applied with DAP, APP, and TPP were lower, indicating lower solubility of Mn applied with these fertilizers. Recoveries of applied Mn also were less in soils with higher pH levels.
Instrument for Automatic Recording of Rainfall and Pan Evaporation
Authors: Dixon R. M. , Degn R. M.
Published: July 2010

An economical combination rain gage and evaporation pan has been developed to provide a useful and dependable tool for soil and water management studies. Two simple direct‐acting float devices were designed to provide alternate methods for sensitive water level control. The simpler of these devices controlled water level to ± 0.22 mm, whereas the more complex device controlled the level to ± 0.01 mm. This instrument, with minor modification, can be used to automatically monitor water supplied to a ponded‐water infiltrometer or to a watertable lysimeter.
An Inexpensive Balance for Accurately Weighing Large Soil Columns
Authors: Miller D. E. , Holman J.
Published: July 2010

An inexpensive balance was constructed, with which weight changes of 1–2 g can be measured in soil columns weighing 80–100 kg.