bluuebunny/crossref_metadata_2025 huggingface dataset:
Soils of the Rio Grande Valley Border in Southern New Mexico
Authors: Gile Leland H.
Published: July 2010

Many kinds of desert soils occur along the border of the Rio Grande Valley in southern New Mexico. These include series in the Torripsamments, Torriorthents, Camborthids, Haplargids, Paleargids, Calciorthids, and Paleorthids. Soil morphology and distribution are related to soil age, texture of parent materials, present and past climate, soil biota, geomorphic surface, and degree of landscape stability. Increase in soil development with age is shown by increasing carbonate accumulation, by increasing silicate clay accumulation in some soils, and by increasing thickness of solum.

Radiocarbon ages of buried charcoal show that some soils are of Holocene age while others are much older and started their development at various times in the Pleistocene. Morphology of the Holocene soils indicates present processes of pedogenesis in this desert region. Certain morphological similarities of Holocene soils to those of Pleistocene age also suggest the character of present processes of pedogenesis in soils that started their development in the Pleistocene. The illuviation of carbonate in nearly all soils and the illuviation of silicate clay in some soils are features of pedogenesis at the present time.

The argillic horizons have been turncated in many soils along the valley border and in others have been engulfed by carbonate or mixed by soil biota. Horizons of carbonate accumulation in these soils are commonly compact and some are indurated, thus are more resistant to erosion and disruption by soil biota. Development of the horizon of carbonate accumulation is therefore a more reliable indicator of approximate soil age than morphology of the B horizon.

Soils discussed in this report have formed in alluvial parent materials derived from noncalcareous rocks, and calcareous dust is virtually the sole source of pedogenic carbonate. Percentages of CaCO3 equivalent for such soils, as determined in the laboratory and controlled by soil morphology, are measures of approximate amounts of dust‐derived illuvial carbonate.
Preventing Water Resorption in Weight Loss Determinations
Authors: Kittrick J. A. , Hope E. W.
Published: July 2010

An important error in weight‐loss determination is resorption of moisture after heating. This is prevented by heating samples in glass ampules in an aluminum block. The ampules are sealed prior to cooling. The average deviation between duplicates for the procedure is ± 0.03% weight loss, or less, when mineral samples are heated to 300C.

Weight losses for several minerals and soils suggest that there is no single time and temperature combination best for all materials, and that heating to 110C gives incomplete weight loss.
New Occurrences of Tabular Halloysite
Authors: Carson C. D. , Kunze G. W.
Published: July 2010

In order to establish the presence of tabular halloysite in soils of widely distributed geographical areas, a study was made of the < 0.2µ clay fraction of four soils. This relatively new clay mineral was found in the Weston soil series from Florida and the Chicaj series of Guatemala. These two soils along with two series from Texas already known to contain tabular halloysite showed the mineral to have moderately high surface areas and cation exchange capacities. Chemical analyses show significant quantities of Mg and Fe present. Upon examination by X‐ray diffraction all clays showed a 7.4A peak characteristic of this clay mineral.
Effect of Temperature on Shear Compliance of Soil with Isosteric Water Vapor Adsorption
Authors: Waldron L. J. , Constantin G. K.
Published: July 2010

Shearing deformation of a soil briquet with equal amounts of adsorbed water at 35.5 and 44.5C was measured from 1 to 86,400 seconds. Deformations at 1 second were the same for both temperatures, but deformation continued at a higher rate thereafter at the higher temperature. The difference in deformation rate at the two test temperatures is greater than the change in fluidity of bulk water at the two temperatures. The isosteric heat of adsorption at the particular water content (equivalent to about 10 monolayers) was about 10% greater than the heat of condensation of water.
Thixotropic Changes with Aging of Synthetic Soil Aggregates
Authors: Blake G. R. , Gilman R. D.
Published: July 2010

Artificially prepared aggregates held at constant water content increased in relative stability with time. The increase is analogous to a thixotropic sol‐gel transformation and to an increase in strength of packed soil with aging. Aggregates were not perceptibly stable to wet sieving at time of formation. Matrix stability of aggregates increased at a rate dependent on water content at which aggregates were stored, on soil type and on storage temperature. High relative stabilities were commonly attained in 24–48 hours at intermediate water contents and at 25C. Extent of slaking resistance was dependent on aging from time of aggregate formation rather than from time of wetting pulverized soil in preparation for pressing into aggregates. The aging phenomenon was independent of organic matter content and of a viable microflora. Data are compatable with the explanation that orientation of water molecules and associated cation equilibrium, and spontaneous shifting of clay particles to positions of lowered potential energy account for the build‐up in aggregate stability during aging.
Desorption of Lindane from Soil as Related to Vapor Density
Authors: Spencer W. F. , Cliath M. M.
Published: July 2010

Vapor‐phase desorption of soil‐applied lindane (γ‐BHC) was studied by measuring vapor density of lindane as affected by soil‐water content, temperature, and lindane concentration. Water content had no effect on vapor density until the soil was dried to a water content below one molecular layer of water. When more than a monomolecular layer of water was present in Gila silt loam, vapor density increased with temperature and lindane concentration until a saturated vapor density, equal to that of lindane without soil was reached at 50, 55, and 62 ppm lindane at 20, 30, and 40C, respectively. Isotherms relating soil lindane concentration to relative vapor density were similar to isotherms relating soil lindane concentration to solution concentration indicating that Henry's Law, p = kc, can be used to predict pesticide behavior in the soil‐water system. Desorption isotherms for lindane on Gila silt loam and bentonite fitted the Freundlich equation. Freundlich constants for vaporphase lindane were similar to those reported previously by others for adsorption of lindane from the solution phase by soil materials.
Urea Conversion to Ammonia in Waterlogged Soils
Authors: Delaune R. D. , Patrick Wm. H.
Published: July 2010

Urea hydrolysis to ammonia proceeded at about the same rate in waterlogged soils and in soils kept at ⅓ bar moisture. Urea hydrolysis took place at an initial rate of about 8 to 12 ppm/hour and began to level off after about 24 hours. Maximum conversion of urea occurred at about pH 8 under both moisture conditions. Volatilization loss of ammonia hydrolyzed from surface applied urea was slightly greater at ⅓ bar than under waterlogged conditions and was considerably greater under all conditions than was loss from surface applied ammonium sulfate. For topdressed urea in flooded soil, urea conversion was much more rapid in the surface layer of soil than in the flood water.
Characteristics of Boron Absorption by Excised Barley Roots
Authors: Bingham F. T. , Elseewi A. , Oertli J. J.
Published: July 2010

Boron absorption by excised barley roots was found to be noncumulative, rapid, and unaffected by pH variations of the substrate in the acid range. However, increases in pH above 7.0 resulted in sharp reductions in absorption. At pH 6.0, changes in substrate temperature, salt composition and level, or addition of KCN and 2,4‐DNP failed to exert any influence on B absorption.

These results indicate that B absorption is a physical, non‐metabolic process acting in response to B concentration gradient and that molecular boric acid is favored for absorption.
Residual Effect of Grain‐Pasture Feeding Systems on the Fertility of the Soil Under a Pasture Sward
Authors: Benacchio S. S. , Baumgardner M. F. , Mott G. O.
Published: July 2010

During 1967, the fertility status of the soils under pasture swards was studied after 4 years of different levels of grain feeding. Nutrient status was assessed by standard soil analysis procedures. The primary concern of this study was to examine the relationship between the amount of grain fed to grazing steers in previous years and the fertility status of the soils at the end of the 1967 growing season during which time no grain was fed to the grazing animals.

A phosphorus accumulation occurred up to a 7.5‐cm depth and was linearly related to the amount of grain fed. The available potassium increased at a growing rate as the level of grain was augmented, indicating a quadratic relationship. This occurred at all sampling levels although the accumulation was much greater in the surface 2.5 cm than at lower depths. The levels of potassium in the surface 2.5 cm of soil were closely related to pasture yield. The pH negatively correlated with potassium availability in the surface 2.5 cm of soil. Potassium level in these pasture soils was a reliable indicator of the fertility value of the excreta from the grazing animal.
Autoradiographic Evidence for the Differential Effect of Four Plant Species in Altering the Calcium Content of the Rhizosphere Soil
Authors: Barber Stanley A. , Ozanne Peter G.
Published: July 2010

Changes in the concentration of Ca in the soil about the roots of four species were observed with autoradiographic procedures. Ryegrass (Lolium rigidum, Gaud.), subclover (Trifolium subterraneum L.), and capeweed (Arctotheca calendula (L.) Levyns) all caused accumulations of Ca about the roots as more arrived by mass‐flow than was absorbed. Lupins (Lupinis digitatus, Forsk.) absorbed larger amounts and caused Ca depletion about the root. There was agreement between calculated and observed changes in the Ca concentration in the rhizosphere zone.
Ferromanganiferous Soil Concretions: A Scanning Electron Microscope Study of Their Micropore Structures
Authors: Cescas Michel P. , Tyner Edward H. , Harmer Richard S.
Published: July 2010

The micropore structures of zoned and nonzoned concretions which occur together in the plow‐depth layer of Flanagan silt loam were examined by scanning electron microscopy. The concretions were characterized by a dominance of small irregularly shaped pores having dimensions varying from 0.2 to 2 µ. Some large pores with dimensions of 2 to 3 µ were observed. The concretion fabric components, for the most part, were masked by massive plasmic depositions indicating that much of the original matrix porosity had probably been infilled during concretion formation. The magnitude of infilling and reduction in original matrix porosity, judged from the frequency and distribution of various sized pores, appeared to be similar for zoned and nonzoned concretions.
Observations of Certain Soil Fabrics With the Scanning Electron Microscope
Authors: Lynn Warren C. , Grossman Robert B.
Published: July 2010

Application of the scanning electron microscope to the study of soil fabrics is presented, and techniques of sample preparation are discussed. Photographs, exhibiting most of the magnification range of the instrument, show examples of spodic, argillic, and fragipan fabrics; an argillan and a skeletan. Particle coatings or the lack of them, interparticle bridges, and orientation of clay on structural surfaces may be observed.
Effects of Loblolly Pine Fertilization on a Piedmont Soil: Growth, Foliar Composition, and Soil Nutrients 10 Years after Establishment
Authors: Moschler W. W. , Jones G. D. , Adams R. E.
Published: July 2010

A field study was conducted in Virginia on an infertile, upland soil in the Piedmont area to determine the response of loblolly pine (Pinus taeda L.) to surface applications of N, two phosphatic fertilizers, and dolomitic limestone. No differences in survival or growth were obtained 10 years after planting. Phosphate increased competition from fireweed (Erechtites hieracifolia) so severely the first year that height growth was significantly reduced, and the effect persisted through the second year. The P content of the foliage was increased by phosphate, while lime increased the Mg content and decreased the Mn content. A high rate of rock phosphate also decreased the Mn content of the foliage. The N, K, Ca, Cu, and Zn contents of the foliage were unaffected by fertilization or liming. The P content of the foliage did not correlate closely with tests of available P in the soil nor did foliar Ca correlate with available Ca in the soil.
Effects of Sources of Phosphorus Under Varying Soil Temperature and Moisture Regimes on the Emergence of Winter Wheat
Authors: Baker J. M. , Tucker B. B. , Morrill L. G.
Published: July 2010

The effects of several sources of phosphorus on the emergence of winter wheat (Triticum aestivum L.) were compared when applied in a band with the seed under controlled temperature and moisture conditions. The detrimental effects of a given fertilizer treatment on emergence increased as temperature increased from 15 to 25C. Increasing soil moisture stress from 1 to 3 bars also reduced emergence. The harmful effects of increasing the temperature from 15 to 25C were greater than the harmful effects of increasing moisture tension from 1 to 3 bars. Emergence was reduced to a much greater extent on a sandy soil than on a medium textured soil for a given fertilizer treatment. The effects of temperature, moisture, and soil texture appeared to be cumulative.

Ammonium polyphosphate, ordinary superphosphate, and concentrated superphosphate had approximately equal effects on emergence and were much less detrimental than monoammonium and diammonium phosphate which were about equal. Ammonium phosphate sulfate decreased emergence to a much greater extent than any other source.

Banding of concentrated superphosphate with the seed reduced emergence as much as 40% in the field. This reduced emergence, however, had no effect on yield of grain.
Preparation of Porous Ceramic Cups to be Used for Extraction of Soil Water Having Low Solute Concentrations
Authors: Grover B. L. , Lamborn R. E.
Published: July 2010

The ceramic cups of soil moisture access tubes were found to contribute excessive amounts of Ca, Na and K to solutions drawn through them. They also adsorbed significant amounts of P from solutions containing P.

Leaching the cups with 1N HCl reduced the contamination of Na and K to acceptable levels. Calcium levels were greatly reduced but significant amounts of Ca contamination continued. Phosphorus adsorption was reduced to an acceptable level.
Steady Infiltration from Line Sources and Furrows
Authors: Raats P. A. C.
Published: July 2010

Steady infiltration from an array of equally spaced line sources or furrows at the surface of a semi‐infinite soil profile is analyzed. The discussion is based on the assumption that the hydraulic conductivity is an exponential function of the pressure head. It is shown that, under this assumption, the matric flux potential and the stream function for plane flows satisfy the same linear partial differential equation. Explicit expressions for the stream function, the flux, the matric flux potential, the pressure head, and the total head are obtained. Some implications with regard to furrow irrigation are discussed. The solution provides a rational basis for the discussion of leaching under furrow irrigation.
Solubility and Hydrolysis of Aluminum in Soil Solutions and Saturated‐paste Extracts
Authors: Richburg John S. , Adams Fred
Published: July 2010

Three Coastal Plains soils that had exhibited different “critical” pH values for maximum cotton yields in field experiments were analyzed for Al solubility. Fertilized soil was used to verify critical pH by a root‐growth experiment in a growthchamber and to obtain displaced soil solutions (⅓‐bar moisture) and water extracts from saturated pastes. Extracts were also obtained from saturated pastes made with 0.01M and 0.05M KCl and with 0.0033M and 0.0167M CaCl2. Solutions were analyzed for pH, Ca, Mg, Mn, K, NH4+, Al, and SO42‐; the remaining ions required for electrical neutrality were assumed to be Cl‐ and NO3‐. A computer program, involving successive iterations of numerous equilibrium equations, was used to solve for ion activities and ion‐pair concentrations, including the Al‐ion species of Al3+, AlOH2+, Al6(OH)153+, and AlSO4+. The ion‐product of (Al3+) (OH‐)3 was considerably larger and much more pH‐dependent with AlOH2+ as the hydrolytic product than with Al6(OH)153+. Calculated (Al3+) values were much lower for polymeric hydrolysis than for monomeric hydrolysis.
Reaction of Montmorillonite with Iron(III)
Authors: Herrera Rafael , Peech Michael
Published: July 2010

The reaction between montmorillonite and Fe(III) was studied at two different degrees of neutralization of the FeCl3 solutions. The adsorption of iron was found to reach a definite saturation value which depended on the initial degree of neutralization of the FeCl3. The maximum amount of Fe(III) adsorbed from FeCl3 solution, having molar OH/Fe ratio = 2, corresponded to the calculated amount of Fe(III) required to form a complete monolayer of octahedrally coordinated Fe(III) on both planar surfaces of the moutmorillonite. The Fe(III)‐montmorillonite complex had a net positive charge at pH 5, which decreased with increase in pH; its cation exchange capacity, however, remained constant at about 45 meq/100 g within the pH range from5 to 7.
Effect of Chemical Pretreatment of Kaolinite Clay Upon The Apparent Self‐Diffusion of Phosphorus‐32
Authors: Phillips Ronald E. , Peaslee D. E.
Published: July 2010

In previous work, it had been observed that “slight” differences in chemical pretreatment of kaolinite clay resulted in large differences in apparent self‐diffusion coefficients of 32P. Apparent self‐diffusion coefficients were measured in a standard kaolinite clay for differing chemical pretreatments. Elemental P was added to each treatment at the rate of 160 ppm. The clay of each treatment was the same physically, but differed chemically due to the chemical pretreatment. Large differences in apparent self‐diffusion coefficients resulted; they were significantly and linearly related to water‐soluble P. A “capacity factor” was calculated from the apparent self‐diffusion coefficients for each chemical pretreatment. The water‐soluble P contents were inversely proportional to the “capacity factors.” The data indicated that systems in which diffusion coefficients of P are measured need to be chemically characterized in detail and that the validity of measuring self‐diffusion coefficients of P in materials such as kaolinite clay needs to be critically evaluated.
Micronutrient Uptake and Mobility Within Corn Plants (Zea mays L.) in Relation to Phosphorus‐induced Zinc Deficiency
Authors: Warnock R. E.
Published: July 2010

Corn plants (Zea mays L.) were grown in greenhouse pots on calcareous soil known to be low in available Zn. Phosphorus was applied to soil at rates of 0 to 520 ppm with concomittant addition of Zn decreasing from 40 to 0 ppm—in inverse concentration. Zinc deficiency occurred at high P and low Zn. Maximum growth occurred at 130 ppm P and 2.5 ppm Zn applied.

Distribution of Zn, Fe and Mn among leaf, stem and root tissue indicated that P and Zn fertilization had altered the mobility of these micronutrients within the plant. Mobility of Fe and Mn was increased by high P and low Zn. Zinc mobility varied opposite to that of Fe and Mn.

Applied P reduced Zn concentration in tissue but not uptake per plant. DTPA‐extractable Zn in soil was not decreased by P applied, but did increase with Zn applied. DTPA‐extractable Fe and Mn increased at high levels of applied P.

Zinc‐deficient plants accumulated a large excess of Fe. Interference from excess Fe is suggested as contributing to physiological malfunction within Zn‐deficient corn plants.
Extraction and Colorimetric Determination of Urea in Soils
Authors: Douglas L. A. , Bremner J. M.
Published: July 2010

A simple colorimetric method of determining urea in soils is described. The soil sample is extracted with 2M KCl containing a urease inhibitor (phenylmercuric acetate), and the extract is analyzed for urea by measurement of the red color formed when an aliquot is heated with diacetyl monoxime and thiosemicarbazide under acidic couditions (phosphoric acid‐sulfuric acid medium). The method is sensitive and precise, and it gives quantitative recovery of urea added to soils. The extraction performed is satisfactory for determination of exchangeable ammonium, nitrite, and nitrate by steam distillation methods.
Solubility and Availability of Sorbed Sulfate in Hawaiian Soils
Authors: Hasan S. M. , Fox R. L. , Boyd C. C.
Published: July 2010

The capacity of volcanic ash soils to adsorb sulfate is related to rainfall, a major factor in weathering. Highly weathered and leached soils developed from ash may contain 7,000 µg/g of sulfate S in the subsoil. This sulfate has very low water solubility. Some less weathered ash soils are almost devoid of sulfates. Desorption of sulfate decreases the solubility of adsorbed sulfate remaining. Sulfate sorption‐desorption isotherms plotted against log concentration of sulfate in equilibrium solutions give approximately straight lines up to 16 to 30 ppms S in solution. Indications are that “first phase” adsorption maxima were attained by highly weathered soil at about 16 ppm S in solution. For less weathered soils, “first phase” adsorption maxima were attained at about 33 ppm S in solution. Pot studies on soils which sorb much sulfate indicate that the soil solution should contain about 5 ppm SO4‐S for adequate nutrition of kikuyu grass. This corresponds to 60 to 80% of first phase adsorption maxima of the ash derived soils. Soils which have low capacity to adsorb sulfate need higher concentrations of sulfate in solution to compensate for low adsorption capacity. A soil which field experiments had shown to be very S deficient was only 10% sulfate saturated.
Phosphate Sorption Isotherms for Evaluating the Phosphate Requirements of Soils
Authors: Fox R. L. , Kamprath E. J.
Published: July 2010

Phosphorus sorption isotherms were constructed for soils which varied in mineralogy, texture, and past history of phosphate fertilization. Equilibrating conditions were: 25C, 0.01M CaCl2, and 6 days. Effects of heavy phosphate fertilization of soils with high phosphate sorption capacities were evident in phosphate sorption isotherms 10 years later. The sorption curves were used as a basis for fertilizing soils in pots so that phosphate in soil solutions varied from about 0.01 to 1.8 ppm P. Millet (Pennesitum typhoides, var. Gahi‐1), was grown for 4 weeks. Yields approached 95% maximum when phosphate in soil solutions was adjusted to 0.2 ppm. The phosphate concentrations at which near maximum yields were attained were little influenced by soil texture or past fertilizer treatments, but absolute yields of millet growing in the sandy Norfolk soil (low phosphate buffering capacity) was greatest if the soil had been previously phosphate fertilized.
Soil Water Evaporation: First Stage Drying as Influenced by Surface Residue and Evaporation Potential
Authors: Bond J. J. , Willis W. O.
Published: July 2010

Evaporation with time was measured from wetted columns of fine sandy loam treated with seven rates of surface residue in six runs with different evaporation potentials. First stage (constant rate) evaporation rate decreased with either increasing residue rates or decreasing evaporation potentials. Total water loss during first stage drying decreased as the rate of first stage evaporation increased. Conversely, water loss for the first 25 days following first stage drying increased as first stage evaporation rate increased. A linear relationship was established by log‐log plotting the duration of first stage drying versus first stage evaporation rate.
Canfield Silt Loam, a Fragiudalf: I. Macromorphological, Physical, and Chemical Properties
Authors: Miller F. P. , Holowaychuk N. , Wilding L. P.
Published: July 2010

More than a half‐million hectares of the moderately well‐drained Canfield soil and its toposequence members occur in northeastern Ohio and northwestern Pennsylvania. These fragipan soils derived from low‐lime glacial till are intensively used for both agricultural and urban purposes. Because this soil is being used for a long‐term study of the disposition of strontium‐90 under natural conditions and because its classification was unconfirmed, 18 profiles from the Ohio Agricultural Research and Development Center at Wooster were described and characterized. The soil profile tended to be bisequal with a moderately well‐developed, loam fragipan occurring at an average depth of 45 cm. The bulk density of the fragipan centered on 1.7, with coarse fragments occupying about 12–16% by volume. The Canfield series was found to contain an argillic horizon above the fragipan and was classed as an Aquic Fragiudalf assigned to the fine‐loamy, mixed, mesic family. The fragipan controls the hydraulic conductivity of this soil, resulting in lateral movement of percolating water across the fragipan surface equivalent to about 30% of the total precipitation. The quantity of subsurface runoff which must accrue from the long slopes, which sometimes exceed 300 m, poses a major problem for the use and management of this soil.
Pyrophosphate Hydrolysis in Flooded Soil
Authors: Hossner L. R. , Phillips D. P.
Published: July 2010

Rate of hydrolysis of pyrophosphate, applied as (NH4)3‐HP2O7·H2O, was measured in four soils under flooded and ⅓ atm moisture content. Hydrolysis was faster under flooded conditions than at ⅓ atm moisture. Pyrophosphate hydrolysis was determined to be a first‐order reaction under flooded conditions but not at ⅓ atm moisture content. The first‐order rate constants under flooded conditions ranged from 2.09 × 10‐5 min‐1 to 1.43 × 10‐4 min‐1 depending upon the soil and temperature of incubation. Half‐life values for applied pyrophosphate varied from 0.6 to 3.9 days. The activation energy for pyrophosphate hydrolysis under flooded soil conditions was calculated to be 4,500 cal/mole for a Katy sl soil.
A Statistical Method for Analysis of Diffusion in Soils
Authors: Nakano Y. , Murrmann R. P.
Published: July 2010

A special Monte Carlo method for use in investigating problems which involve random processes is developed. This approach differs from the usual Monte Carlo method for solution of differential equations in that the random process itself is constructed directly. The power of this approach is demonstrated by application of the method using two examples. In one case, the effect of thermal gradient on ionic diffusion through thin films of interfacial water in frozen clay is examined. The predicted ionic distribution is in agreement both with experimental data and with the result obtained by exact solution of the diffusion equation. In the second example, the distribution of acetone deposited in soil near the soil‐atmosphere interface is calculated for a two‐layer profile in which the adsorption coefficient and void‐porosity vary between horizons.
Calculation of the Leaching required to Reduce the Salinity of a Particular Soil Depth beneath a Specified Value
Authors: Terkeltoub Richard W. , Babcock K. L.
Published: July 2010

Soil columns containing either Yolo silty clay loam or Hanford sandy loam were prepared with vertically nonuniform salt (Na+, Ca2+, Mg2+, Cl‐) and moisture distributions and with gypsum (CaSO4 · 2H2O) present in the surface soil. The columns were irrigated at both fast and slow rates of water application with a water containing Na+, Ca2+, Mg2+, and Cl‐. A simple method for calculating salt movement in soils successfully approximated the resultant salt profiles.

A variation in the salt movement computation method was devised for calculating the leaching required to lower the salinity of a particular soil depth to less than a specified value. The method was experimentally verified on both a Yolo and a Hanford soil column, each with vertically nonuniform initial salt and moisture distributions.
Fungal Growth Responses to Osmotic as Compared to Matric Water Potential
Authors: Adebayo A. A. , Harris R. F.
Published: July 2010

The osmotic and matric water potential characteristics of Phytophthora cinnamomi and Alternaria tenuis, fungi of widely different tolerance to water stress, were evaluated using agar media of varying nutritional status and three texturally different soils. The water potential of the agar media was controlled osmotically with KCl or sucrose. For the osmotic soil system, soil water content was maintained approximately constant and the desired water potential range was achieved by adding KCl solutions of different concentrations to air‐dry soil samples at a level equivalent to the water content of the field moist soils; for the matric system, decreases in water potential were achieved by adding decreasing volumes of water to air‐dry soil according to the moisture retention characteristics of the soils. Fungal growth was determined by measuring changes in colony diameter with time.

Osmotic water potentials for optimum fungal growth in agar and soil systems were similar to the water potentials for optimum growth in soils of matric‐controlled water potential. However, with decreasing water potential both fungi were much less tolerant to matric than to osmotic stress, emphasizing that fungal response to decreasing soil water cannot be explained solely on a water potential basis, but must include consideration also of changes in other water‐related soil properties such as solute transport. Fungal responses to matric and osmotic water potential differences were not related to soil texture.

From a practical standpoint, the matric potentials at which growth extinction occurred were numerically one‐half to two‐thirds of the corresponding osmotic potentials at which growth ceased. If this relationship holds for other fungi and other soils, fungal growth responses to water potential obtained using simple agar systems of osmotic‐controlled water potential should provide useful approximations of the matric water potential relations of fungi in soil, thereby facilitating prediction of the maximum soil water potential range within which specific fungi may develop competitively in natural soils.
Nitrification Inhibition in Soil: I. A Comparison of 2‐Chloro‐6‐(trichloromethyl)pyridine and Potassium Azide Formulated with Anhydrous Ammonia
Authors: Parr J. F. , Carroll B. R. , Smith S.
Published: July 2010

The relative effectiveness of 2‐chloro‐6‐(trichloromethyl) pyridine and potassium azide as nitrification inhibitors, formulated and applied to soil with anhydrous NH3, was compared in laboratory and growth chamber experiments. At an inhibitor level of 10 ppm, and after 14 days, NH4+ concentrations 0 to 2.5 cm from the point of release of NH3, NH3 + KN3, and NH3 + N‐Serve were 695, 810, and 887 ppm N respectively, while after 56 days corresponding values had decreased to 129, 316, and 609 ppm N. After 14 and 56 days of incubation in unplanted pots, KN3 was 60 and 40%, respectively, as effective as N‐Serve in suppressing nitrification. N‐Serve was more effective than KN3 during longer incubation periods because of its greater residual activity.

In general, yields of ryegrass (Lolium sp.) and cotton forage (Gossypium hirsutum L.) followed the order of NH3 = NH3 + KN3 > NH3 + N‐Serve. The greater residual activity of N‐Serve compared with KN3 and the absence of root development in the center of the NH3 + N‐Serve retention zone, as well as the stunted and flaccid appearance of roots, was indicative of potential phytotoxicity of N‐Serve in this particular mode of application.
Transition Matrix Approach to Numerical Classification of Soil Profiles
Authors: Norris J. M. , Dale M. B.
Published: July 2010

In conventional classification of soil profiles the relative positions of pedogenic horizons within the profile are usually considered. In this paper numerical classification methods are described which consider the relative positions of samples in the profile. The methods are applied to twenty profiles, each described by eight field properties and eight laboratory tests determined on samples taken from 10 fixed depths. Results of these two numerical classifications are compared using an ordination procedure. Advantages and pedological applications of the methods are discussed.
A Test of the Uniqueness of the Soil Moisture Characteristic During Transient, Nonhysteretic Flow of Water in a Rigid Soil
Authors: Smiles D. E. , Vachaud Georges , Vauclin Michel
Published: July 2010

Quick response water potential and nondestructive water content measurements indicate that during transient, nonhysteretic flow of water following a rapid change of water content at one end of a horizontal column of soil, the soil moisture characteristic curve is a unique function during sorption from a particular initial water content, but during desorption there is a multiplicity of curves. These transient curves depend on the magnitude of the imposed water content change and also on the speed with which static equilibrium is achieved after the change.

The consequences of this behavior are discussed in terms of diffusion theory, and it is concluded that it would be unwise to apply this theory to desorption situations until the quantitative significance of this behavior is determined for other materials.
Effect of Liming on the Soil Test Level of Phosphorous as Determined By Three Methods
Authors: Griffin G. F.
Published: July 2010

Changes in extractable P resulting from additions of Ca(OH)2 to samples of 13 acid Connecticut soils varied with soil type and soil extractant. The average pH increase from 5.3 to 7.7 resulted in the following average changes in extractable P: modified Morgan, +123%; North Carolina, +27%; Bray no. 1, −23%. Changes in Bray no. 1 extractable P were affected less by soil differences than changes in P extracted by the other two methods.
Nitrification Inhibition in Soil: II. Evaluation of Anhydrous Ammonia‐Potassium Azide Solutions in Eastern Washington
Authors: Papendick R. I. , Parr J. F. , Smith S. , Smiley R. W.
Published: July 2010

The effectiveness of potassium azide (KN3) as a nitrification inhibitor for field‐applied anhydrous NH3 was evaluated on a Naff silt loam in the winter wheat (Triticum aestivum L.) area of eastern Washington. Formulations of KN3 in liquid NH3 of 0, 2, and 6% (w/w) were applied to fallow soil in August 1969 at a rate of 112 kg N/ha (81‐cm spacing) with a special field applicator. The 2% formulation was also applied at a rate of 224 kg N/ha. The NH3 retention zone was sampled periodically through February 1970 and analyzed for NH4+‐N, NO2‐‐N, and NO3‐‐N. Both levels of KN3 were effective in reducing the nitrification rate during the early post injection period, but the higher level was more effective at later dates. Two months after application, the amounts of NO3‐‐N recovered from the retention zone as percent of total extractable N were 67, 48, and 36 for NH3 alone, NH3 + KN3 (2%), and NH3 + KN3 (6%), respectively. Percentage amounts of NO3‐‐N decreased with increase in N application rate. Nitrification inhibition due to KN3 was still evident 6 months after application, particularly at the high N rate. The inhibitory effect of low soil temperature during the winter months was also apparent. These results indicate that KN3 formulated with anhydrous NH3 was an effective nitrification inhibitor for this N source.
Rapid Analysis of Soil Nitrate with Chromotropic Acid
Authors: Sims James R. , Jackson Grant D.
Published: July 2010

Colorimetric analysis of nitrate in soil extracts using chromotropic acid (CTA) was studied and compared to the results obtained by the phenoldisulfonic acid (PDA) method. Extracting solutions of 0.5M MgSO4, saturated CaSO4, and a 0.2% Ca(OH)2 suspension were investigated. The three extractants were equally effective in recovering NO3‐; however, the clearest extracts were obtained with Ca(OH)2. Soil‐to‐extractant ratios of 1:2.5, 1:5, and 1:10 were studied. The 1:5 ratio effectively extracted NO3‐ and resulted in appropriate NO3‐ concentrations for color development. A shaking time of 15 min was adequate to extract a maximum of NO3‐. In a NO3‐‐N recovery study, equivalent amounts of NO3‐ were recovered by the CTA and PDA methods. Results of nitrate analyses by the two methods were significantly correlated (p = .01). Nitrate determined by the chromotropic acid procedure was positively correlated (p = .05) with the yield of winter wheat (Triticum aestivum L.) and was negatively correlated (p = .01) with response of winter wheat to N fertilizer additions. The new procedure has the advantages of rapidity, simplicity, sensitivity, and relative freedom from interference.
Domains and Quasi‐Crystalline Regions in Clay Systems
Authors: Quirk J. P. , Aylmore L. A. G.
Published: July 2010

A number of terms have been used by different authors to describe regions of near‐parallel alignment of the plate‐shaped crystals in clay materials. This has resulted in some confusion through inadequate definition and misconceptions in the usage of these terms. Use of the term quasi‐crystal to describe the regions of parallel alignment of individual alumino‐silicate lamellae in montmorillonite and of the term domain to describe the regions of parallel alignment of crystals for illite and other fixed lattice clays is recommended in preference to terms such as tactoid or crystal of montmorillonite.

The similarity in behavior of a domain of illite crystals and a montmorillonite quasi‐crystal is illustrated. These regions show a marked difference in swelling behaviour between sodium and calcium systems.
Nuclear Magnetic Resonance Spectra of Acetate Derivatives of Soil and Plant Inositol Phosphates
Authors: L'Annunziata Michael F. , Fuller Wallace H.
Published: July 2010

Acetate derivatives of inositols found in soils and plants were prepared subsequent to the extraction of the inositols as phosphates. Yields as high as 88% were obtained with the acetylation of samples as small as 20 mg of the inositol. The increase in molecular weight of the inositol upon acetylation was advantageous due to the small amounts of inositols usually available from soils and plants. The nuclear magnetic resonance spectra (NMR) of these acetate derivatives permitted the observation of the number of axial and equatorial acetoxy groups. The axial or equatorial position of an alkyl substituent on one of the oxygen atoms was easily observed by means of the NMR spectra of the acetate derivative. Improved NMR spectroscopic techniques can permit the analysis of the stereochemistry of soil and plant inositol phosphates without the requirement of an authentic sample as a standard for comparison.
Illite Solubility
Authors: Routson R. C. , Kittrick J. A.
Published: July 2010

Equilibrium solubilities of the 0.2–2.0µ size fraction of three K+‐saturated illites were determined in high‐pH aqueous solutions. Beavers Bend, Fithian, and Goose Lake illites were selected for the study. Solubility products were found to be 10‐77.6±0.1 for Beavers Bend, 10‐76.6±0.3 for Fithian, and 10‐76.7±0.2 for Goose Lake illites, based on mean calculated formulae of K0.53 (Al1.66, Fe0.20, Mg0.13) (Si3.62, Al0.39) O10 (OH)2, K0.64 (Al1.54, Fe0.29, Mg0.19) (Si3.51, Al0.49) O10 (OH)2, and K0.59 (Al1.58, Fe0.24, Mg0.15) (Si3.65, Al0.35) O10 (OH)2, respectively. From the solubility product and known thermodynamic relationships, the standard free energy of formation (ΔG) was calculated for each illite. ΔG's were −1267.6±0.9 for Beavers Bend, −1270.6±1.0 for Fithian, and −1265.3±1.0 kcal/gram formula weight for Goose Lake illities.
Pesticide Mobility in Soils I. Parameters of Thin‐Layer Chromatography
Authors: Helling Charles S.
Published: July 2010

Pesticide movement was studied using the recently developed soil thin‐layer chromatographic (TLC) method (Science 162:562, 1968). Thin layers of soil, the adsorbent phase, are developed with water using techniques analogous to conventional TLC.

Mobility, expressed as RF values for frontal movement, was insensitive to these parameters: removal of coarse or medium sand, movement distance, soil layer thickness, temperature, and sample size (0.3 to 50 µg). Water flux was modified by physical, soil amendment (inorganic and organic additives), and solvent amendment methods. Increased flux may slightly increase mobility of pesticides. The mobilities of 2,4‐D and atrazine decreased markedly in > 0.5M NaCl solution, whereas some movement of paraquat then occurred. Distance to the wetting front on soil TLC plates was linearly related to the square root of time.

Three methods of visualizing radioactive pesticide movement were compared: autoradiography, radiochromatogram scanning, and zonal extraction.
Pesticide Mobility in Soils II. Applications of Soil Thin‐Layer Chromatography
Authors: Helling Charles S.
Published: July 2010

Forty pesticides were grouped into five categories based on relative mobilities on Hagerstown silty clay loam plates, using soil thin‐layer chromatography. Diffusion was also examined in moist and air‐dry soils. Methyl esterification greatly reduced mobility of herbicides while increasing diffusion and volatility. The surfactant Tween 20 (1% in solution) increased 2,4‐D movement, but 0.5% solutions of five surfactants were relatively ineffective with several herbicides. Metabolites of atrazine, propanil, and 2,4‐D were less mobile than their parent compounds. Two chlorinated dibenzo‐p‐dioxins, potential 2,4,5‐T impurities, were immobile. Movement of components in chlorpropham/propham/p‐chlorophenyl methylcarbamate and atrazine/propachlor combinations were mutually independent.

Dicamba and fenac RF values were directly related to soil pH in the range of pH 5.0 to 6.5–6.7. Other soil modifications included in situ oxidation of soil organic matter and the use of model clays. Chlorpropham and propham mobilities were increased by removal of organic matter. Diphenamid was less mobile in oxidized soil, immobile in Ca‐montmorillonite, and moderately mobile in kaolinite.
Pesticide Mobility in Soils III. Influence of Soil Properties
Authors: Helling Charles S.
Published: July 2010

Soil parameters influencing pesticide movement were isolated using simple correlation and multiple linear regression analyses. Mobilities of 12 pesticides on 14 soils were first characterized by soil thin‐layer chromatography. Mobility of nonionic compounds was inversely related to adsorption of similar compounds, field moisture capacity, organic matter and clay contents, and cation‐exchange capacity. Mobility of acidic compounds (dicamba, picloram, fenac, and 2,4‐D) was directly correlated with soil pH and inversely with picloram adsorption. Pesticide mobility tended to be directly related to increased water flux.

When soils were grouped according to their clay mineralogy, there was a tendency for movement of acidic pesticides to be directly related to montmorillonitic clay content and inversely related to nonmontmorillonitic clay content.

Regression equations usually contained field moisture capacity, water flux, and often simazine or chlorpropham adsorption terms for predicting movement. These parameters are highly correlated with soil organic‐matter content, which does not itself appear in the regression equations. The average deviation of predicted from observed mobility, across all soils and pesticides, was 0.04 RF units.
Electron Scanning Studies of the Fabric of Fracture Surfaces
Authors: Eswaran H.
Published: July 2010

Fracture surfaces of soil peds were studied with the scanning electron microscope (SEM). An attempt was made to correlate such studies with the classical petrographical study of the soil. Cambic, spodic, argillic and oxic horizons were examined and some of the more significant properties were evaluated. A brief discussion has been included regarding the problems involved in using SEM technique in soil micromorphology.
Movement and Persistence of Dieldrin and Lindane in Soil as Influenced by Placement and Irrigation
Authors: Cliath M. M. , Spencer W. F.
Published: July 2010

Redistribution and recovery of dieldrin and lindane were measured in two calcareous, low organic‐matter soils with and without irrigation. The insecticides were uniformly mixed within the 0–7.5 or 7.5–15 cm depths by excavating the soil, mixing the soil and insecticide in a cement mixer, and placing the treated soil back in the excavation.

Dieldrin was highly stable and persistent, although volatilization apparently was a significant pathway for loss of dieldrin when the surface soil was wet and dieldrin was placed in the surface layer of soil. Dieldrin apparently did not move significantly with the water and moved very little by diffusion, either upward or downward from its zone of application. No evidence was found that catalytic breakdown of dieldrin occurred in the hot, dry soil.

The movement and the dissipation of lindane from both soils were markedly greater than for dieldrin. Lindane moved downward with water application, especially in the sandy loam soil. Lindane was lost by volatilization and also by degradation, as considerable quantities of gamma‐pentachlorocyclohexene (PCCH) were found in the soil extracts.

The results suggest that volatilization losses can be reduced or prevented by keeping the soil surface dry or by incorporating or injecting insecticides into the soil.
Apparent Nitrogen Fixation in Soil Influenced by Prescribed Burning
Authors: Jorgensen J. R. , Wells C. G.
Published: July 2010

Nitrogen increases of 23 kg/ha/year were associated with annually burned loblolly pine (Pinus taeda L.) in the lower Coastal Plain of South Carolina. Unburned areas showed no increase of N. Nitrogen fixation in cores from the forest floor and at depths of 0–1 and 3–4 cm was assayed using the acetylene‐ethylene technique, with the ethylene produced related to N fixation. In the 0–4 cm of mineral soil on burned plots more than 4 g/ha of N were fixed in 24 hours, but only 0.2 g/ha were fixed on unburned areas. Up to 61 g/ha of N were fixed in 24 hours in individual samples from burned areas. Most fixation in the burned areas took place in 14% of the samples; half the samples fixed no N or an insignificant amount, regardless of burning treatment. Fixation rate increased as moisture content increased from below to above field capacity and as temperature increased from 25 to 35C. However, the rate of increase related to temperature and moisture was usually associated with samples which had fixed N under less favorable conditions, rather than with the initiation of fixation in more samples.
Stability of Montmorillonites: II. Aberdeen Montmorillonite
Authors: Kittrick J. A.
Published: July 2010

Six montmorillonite samples from Aberdeen, Mississippi were equilibrated with various solutions for 3–4 years. Under the conditions of these experiments, Aberdeen montmorillonite was found to be less stable than Belle Fourche montmorillonite and kaolinite. Locating the Aberdeen solubility line under conditions where it is metastable was difficult because of the tendency of the samples to approach the nearest stable solubility line. It was possible to locate the position of the metastable montmorillonite solubility line only because two of the six samples resided there briefly before approaching the more stable kaolinite solubility line. The resulting three points were in close agreement with the calculated slope and intercept of the montmorillonite solubility line on pH‐⅓pAI3+ vs. pH4SiO4 axes, as derived from the unit cell formula of Aberdeen montmorillonite. A ΔG of −2450.3±0.1 kcal per mole was obtained for Aberdeen montmorillonite, based upon the assumption that Fe3+ in solution was controlled by hematite.