bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffusion and Analysis of Carbon‐14 Labeled Dieldrin in Soils
Authors: Farmer W. J. , Jensen C. R.
Published: July 2010

Liquid scintillation techniques were used in developing a rapid method for the analysis of carbon‐14 labeled dieldrin in soils. Treated soil samples up to 1 g in weight were added to 20‐ml liquid scintillation counting vials and the labeled dieldrin extracted into the toluene counting media. The diffusion coefficient of dieldrin was measured in soils of varying texture and relative humidity at 20C in transient state systems. At 53% relative humidity the diffusion coefficient in eight soils varied between 0.049 and 0.36 mm2/week. No correlation was found between soil texture and the diffusion coefficient. The diffusion coefficient in three soils varied between 0.40 and 0.64 mm2/week at 75% relative humidity and between 3.8 and 9.7 mm2/week at 94% relative humidity. At the higher humidity, the diffusion coefficient increased with increasing clay content.
Seasonal Variability of pH and Lime Requirements in Several Southern Michigan Soils When Measured in Different Ways
Authors: Collins J. B. , Whiteside E. P. , Cress C. E.
Published: July 2010

The seasonal variability of pH and lime requirement of the plow layer of 13 soil series, at 19 sites, by various methods on field‐moist, air‐dry and oven‐dry samples were observed from May through September 1966 near East Lansing, Mich. Several factors associated with variation in pH were also observed.

At the beginning of the season, the mean glass electrode‐pH of air‐dry and oven‐dry samples measured in each of three suspending media—water, 1.0N KCl, and 0.01M CaCl2—were each significantly lower than the corresponding field‐moist pH. On air‐dry samples, pH measurements with the glass electrode in water are significantly correlated with those in 0.01M CaCl2 (r = 0.96) and in 1.0N KCl (r = 0.92) or those measured with the Truog kit (r = 0.90).

The pH of field‐moist samples in water showed a maximum seasonal variability of 1.6 pH units and an average variation of 0.8 pH unit. The pH of samples in 1.0N KCl showed the least average seasonal variability of the methods used, 0.2 pH units. Electrical conductivity gave the highest correlation (r = ‐.82) with seasonal variability of pH on air‐dry samples in water. The glass electrode pH on air‐dry samples in 1.0N KCl were better correlated (r = .63) with percentage base saturation than those in water (r = .53) and slightly better than those in 0.01M CaCl2 (r = .61).

Four of 11 sites studied had a lime requirement early in the season but each of the 11 sites had a lime requirement in midsummer.
Organic Phosphorus and Inositol Phosphates in Molecular Size Fractions of a Soil Organic Matter Extract
Authors: Moyer J. R. , Thomas R. L.
Published: July 2010

Soil organic matter extracted with the chelating resin Dowex A‐1, was fractionated into three fractions on a column of Sephadex G‐75. The first fraction, which has an approximate lower molecular weight limit of 50,000, contained 36% of the total organic P in the extract. The second fraction, with intermediate molecular weights in the range 1,000–50,000, contained 31% of the P. The third fraction, which was considered below the fractionation range and therefore is below 1,000 molecular weight, contained 7.8% of the organic P in the extract. Inositol phosphates were detected in the second and third fractions but not in the first fraction. Inositol phosphates in the third fraction were considered to be in the free form, while those in the second fraction must be in either a polymer form or bound to other organic compounds.
Influence of Nitrogen on Phosphorus Absorption and Translocation in Zea mays
Authors: Thien S. J. , McFee W. W.
Published: July 2010

The effect of metabolized N and N in solution on P absorption and translocation in corn was studied in growth chamber experiments. Two‐week‐old corn plants of various N and P contents were prepared by pre‐treatment in NH4+, NO3‐, P or water solutions for 24 hours. Plants were then transferred to treatment solutions containing labelled P alone or with a N source. Uptake and translocation of labelled P was continuously monitored for 6 hours.

Nitrogen pretreatment of corn plants significantly increased P absorption and translocation rates during the following 6 hours. These effects were absent when N was omitted from the pretreatment solution and accompanied P only during the treatment period, indicating no companion effect of these two nutrients on movement into root cells. Phosphorus absorption and translocation were stimulated to different degrees suggesting two separate transport systems involved in P uptake and translocation. The observations suggest the existence of a N‐requiring metabolite influencing the efficiency of P absorption and translocation mechanisms in corn. No significant difference between the N sources, NH4Cl or NaNO3, was observed.
Zonal Salinization of the Root System with NaCl and Boron in Relation to Growth and Water Uptake of Corn Plants
Authors: Bingham F. T. , Garber M. J.
Published: July 2010

Corn seed (Zea mays L.) was germinated in the top portion of a soil column separated by thin amber wax layers into three equal horizons. Each soil unit contained 500 g of soil aggregates, a tensiometer, and tubing to facilitate irrigation and drainage. Differential treatments of NaCl and B were separately imposed for 3 to 4 weeks upon the various root zones once the plant had extended roots throughout all horizons. Each horizon was irrigated with a dilute nutrient solution with and without NaCl to have an EC of 12 mmho/cm for the NaCl treatments; and with H3BO3 to have concentrations of 10‐, 20‐, and 40‐mg B/liter for the B treatments.

Results include data on plant growth, water use, and ion uptake. The NaCl treatments were associated with reductions in root growth and water use/plant in proportion to percent root system treated. However, little or no reduction in shoot weights occurred upon zonal salinization of two‐thirds of the root system. Also, the NaCl treatments did not restrict uptake of NPK to any serious extent. The B experiments showed corn plants to be injured by soil solution levels of 20 mg B/liter or greater, the degree of injury being a function of soil solution B and percent root system under treatment.
Runoff as Affected by Salt Treatments and Soil Texture
Authors: Kemper W. D. , Noonan L.
Published: July 2010

Runoff was measured on soils during rains applied with a rainfall simulator in the laboratory. These soils were dried and rained on again and this sequence was repeated several times with runoff measured during each rain. The texture providing maximum runoff consisted of high sand contents (50 to 80%). Higher percentages of clay and silt resulted in surface cracking and considerable infiltration through those cracks.

Marked increases occurred in runoff due to NaCl treatments and decreases occurred due to CaSO4 treatments. Since the amounts of the salts required was small (244 to 896 kg/ha) and the cost of these salts is low (approximately $1.00/50 kg in bulk), emergency water control of bare surfaces using salt treatments appears to be economically feasible.
Translocation of Hydrophobic Substances into Soil by Burning Organic Litter
Authors: DeBano L. F. , Mann L. D. , Hamilton D. A.
Published: July 2010

Unknown hydrophobic substances were vaporized in surface layers of litter and water repellent soil by an imposed heat treatment. The vaporized substances moved downward and condensed in different test soils where they produced a water repellent layer. The thickness of the water repellent layer in the underlying test soil increased as per cent soilt and clay decreased. The thickest and most intensely water repellent layer was produced in a uniform 35‐mesh sand. The effect of texture on water repellency was attributed to large differences in specific surfaces of the soils which ranged from 0.0077 to 55 m2/g. The induced water repellency was not directly related to a given amount of organic matter translocated by the heat treatment. Generally, however, the degree of water repellency increased as the amount of translocated organic matter increased in a given test soil.
Nonpedogenetic Texture Bands in Outwash Sands of Michigan: Their Origin, and Influence on Tree Growth
Authors: Hannah Peter R. , Zahner Robert
Published: July 2010

Origin of many thick well‐developed nonpedogenetic texture bands is attributed to deposition in glacial outwash concurrent with the deposition of adjoining layers of sand outwash. Nonpedogenetic bands are thicker, less stratified, finer textured, and more massive and convoluted than pedogenetic bands. Roots of forest trees tend to branch and proliferate in the region immediately above thin bands and penetrate and develop normally in thick till‐like bands. Site indexes for natural jack pine (Pinus banksiana Lamb.) and bigtooth aspen (Populus grandidentata Michx.) stands, and stemwood production in red pine (Pinus resinosa Ait.) plantations are significantly higher on soils with prominent texture bands than on soils where bands are absent or weakly developed.
Effect of Complexing Agents and Acids on the Diffusion of Zinc to a Simulated Root
Authors: Elgawhary S. M. , Lindsay W. L. , Kemper W. D.
Published: July 2010

Porous ceramic tubes were embedded in soil tagged with 65Zn. Solutions were slowly passed through the tubes, allowing diffusion of the solutes into the soil and diffusion of Zn from the soil to the tubes. Solution from the tubes was analyzed for 65Zn. The solutes used were EDTA (ethylenediaminetetraacteic acid), HCl, citric acid, an amino acid mixture, and glucose. EDTA caused the greatest increase of Zn transport into the ceramic tubes (simulated roots). For example, when 10‐3M EDTA was passed through such a tube Zn diffusion increased 17‐fold over that occurring with water alone. The effectiveness of other agents decreased in the order listed above. Increasing the concentrations of solute generally increased 65Zn diffusion. This study demonstrates how complexing agents or acids from root exudates or from decomposing organic residues in soils may increase the transport and availability of insoluble nutrients.
Nitrogen Immobilization in Flooded Soils
Authors: Broadbent F. E. , Nakashima T.
Published: July 2010

Nitrogen immobilization in flooded soils amended with straw was measured by following incorporation of tagged inorganic N into the soil organic fraction. Increases in tagged organic N were found to be highly correlated with net immobilization as measured by decrease in mineral nitrogen in the soil. Since most of the soils used contained clay minerals capable of ammonium fixation, apparent immobilization figures were corrected by subtraction of clay‐fixed ammonium.

In comparisons of nitrogen immobilized under different soil conditions it was found that values obtained in flooded soils were intermediate between those obtained under aerobic and anaerobic conditions. The nitrogen factor, or additional N immobilized, per unit weight of straw, was found to vary with quantity of straw added, nitrogen content of the straw, and nature of the soluble nitrogen supplied, but in no case was it negligible. Rice straw (Oryza sativa L.) containing 0.47% N immobilized an additional 0.51% N in a flooded soil, and another sample of rice straw containing 1.17% immobilized 0.43% N.
Concentration of NH3(aq) Required for Incipient NH3 Toxicity to Seedlings
Authors: Bennett A. C. , Adams Fred
Published: July 2010

Short term experiments with sudangrass (Sorghum sudanensis L.) and cotton (Gossypium hirsutum L.) were conducted in a growth chamber to determine incipient toxic levels of NH3(aq). Sudangrass seedlings were grown for 14 days in potted Lucedale sandy loam surface soil treated with different rates of N from NH4OH, (NH4)2SO4, and (NH4)2HPO4. Root growth of cotton seedlings was measured over a 3‐day period in split‐root experiments in which the upper portion of the root medium was a sandy loam surface soil and the lower portion was either a nutrient solution or a treated soil at various levels of pH and ammoniacal‐N. Symptoms of NH3 toxicity were evident on sudangrass foliage at NH3(aq) concentration in the soil solution in situ of 0.17mM and greater; there was no evidence of NH3 toxicity at 0.13mM and less. Symptoms of NH3 toxicity on cotton roots were evident in soil solutions in situ at NH3(aq) concentrations of 0.24mM and greater but not at 0.17mM and less; in nutrient solutions, symptoms were evident at 0.22mM NH3(aq) but not at 0.16mM. The critical concentration for incipient NH3 toxicity was concluded to be 0.15 to 0.20mM NH3(aq).
Effects of Aluminum Toxicity and Phosphorus Fixation on Crop Growth on Oxisols in Natal
Authors: Reeve N. G. , Sumner M. E.
Published: July 2010

Simple, routine methods for estimating exchangeable Al and P‐fixing capacity of acid soils are described. A glass‐house study on eight Oxisols revealed marked growth response of ‘trudan’ (Sorghum sudanense) to amelioration by lime, gypsum, and Ca silicate which is ascribed to elimination of Al toxicity rather than to improved P availability. Growth response to ameliorants took place up to the point of elimination of exchangeable Al after which a significant reduction in yield occurred. P fixation is shown to be a major fertility limitation in the soils studied. Since no apparent relationship between P fixing capacity and exchangeable Al existed and since lime did not decrease P fixation despite its ability to eliminate soluble Al, it is concluded that P fixation is the result of an adsorption reaction rather than a precipitation reaction. Although the soils studied are all capable of fixing large quantities of P considerable variation exists between them. Fertilizer recommendations based only on an estimate of available P in the soil per se could thus be in serious error.
Quantitative Prediction of Leaching in Field Soils
Authors: Terry D. L. , McCants C. B.
Published: July 2010

Leaching experiments were conducted under controlled water regime conditions on a variety of soils in the field to study the distribution of certain ions by percolated water. When NH4, NO3, and K were leached, their movement was generally in the form of a “normal” distribution. The movement of Mg was not as well defined as the other ions.

Multiple regression equations for predicting the leaching of these ions were developed which utilize the parameters of a normal distribution as the dependent variables and properties of the soil and quantities of percolated water as the independent variables. The R2 values for mean movement ranged from 0.92 to 0.97 and those for the standard deviation from 0.56 to 0.91. The principal independent variables were (i) quantity of percolated water, (ii) soil porosity as expressed by the weighted porosity index, (iii) cation exchange capacity, and (iv) the water content at 0.1 bar suction.
Effect of American Beech Trees on the Gamma Radioactivity of Soils
Authors: Gersper P. L.
Published: July 2010

Various factors that affect the distribution of gamma‐emitting radioisotopes in soils under mature American beech trees (Fagus grandifolia L.) were investigated. Because of its smooth bark and consequent greater amounts of stemflow this species concentrates more fallout radioisotopes in soil near its stem than most other species.

Soil near the stems of beech trees contained considerably more fallout and was subjected to greater leaching of natural radioisotopes, to a depth of 30 cm or more, than soil not affected by stemflow water. Depth penetration of fallout and leaching of natural radioisotopes was greater in Dekalb fine sandy loam than in Bennington silt loam.

Radioisotope distribution in soil under these trees was also affected by variations of stemflow around the stems, slope gradient, and the quantity and distribution of organic litter on the forest floor. Near two trees that had variable stemflow, the surface soil contained an average of five times more fallout on the high‐stemflow sides of the stems than on the low‐stemflow sides. Under a beech tree growing on a 20% slope, soil on the downslope side of the stem contained more fallout than soil on the upslope side. Organic litter had a much higher content of fallout than of naturally occurring radioisotopes.

As a consequence of the greater concentrations of fallout, herbaceous plants, spicebush (Lindera benzoin L.), and American beech saplings growing near the stems of mature beech trees had higher uptakes of these radioisotopes than those growing farther from the stems.
Molecular Weight of Montmorillonite from Optical Transmission Measurements
Authors: Lahav N. , Banin A.
Published: July 2010

The weight average molecular weight of small Na‐montmorillonite particles in aqueous suspension have been determined by means of optical density (OD) measurements. In the wavelength range of λ = 4000A to 6000A and in dilute clay suspension which obeys Beer‐Lambert Law, the slope of the straight line of log (OD) vs. log λ is proportional to the major dimension of the particles. Assuming a disc geometry and the number of unit layers in a clay particle, and working with suspension with a slope near −4, the weight average molecular weight was found by using light scattering theory. The results agree reasonably with other data from the literature.
Adsorption of s‐Triazines by Montmorillonite As a Function of pH and Molecular Structure
Authors: Weber J. B.
Published: July 2010

The effect of pH on the adsorption of 16 structurally related s‐triazines by Na‐montmorillonite was investigated. Slurry type adsorption techniques were used. The compounds included ametryne, desmetryne, prometryne, GS 14253, GS 14260, GS 16065, atrazine, SD‐15418, dyrene, atratone, prometone, GS 28533, melamine, ammeline, ammelide, and benzoguanamine. Maximum adsorption occurred at pH levels in the vicinity of the pKA of each compound. The amount of adsorption which resulted was related to the substituent groups on the triazine ring. Comparisons of compounds substituted in the 2‐position indicated that adsorption of the s‐triazines by montmorillonite decreased in the order: ‐SC2H5 > ‐SCH3 > ‐OCH3 > OH > ‐Cl. Substitutions made in the 4 and 6 positions indicated that dialkylamino compounds were adsorbed in greater amounts than monoalkyl substituted compounds and that adsorption decreased in the order: C4H9(t) > C4H9(s) > C2H5 > C3H7(i) > CH3 > C(CH3)2CN. The more basic compounds were adsorbed in greater amounts than compounds of lower basicity.
Factors Affecting Soil Arylsulfatase Activity
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

A study of the effects of various soil pretreatments on soil arylsulfatase activity showed that storage at −10C is a satisfactory method of preserving field‐moist soil samples for assay of arylsulfatase activity. Storage of field‐moist soils at 5C or 22–24C for 3 months led to a decrease in arylsulfatase activity (average, 8% at 5C, 18% at 22–24C), but storage at −10C for the same period did not significantly affect this activity. Air‐drying of field‐moist soils at 22–24C caused a marked increase in arylsulfatase activity (average, 43%), and oven‐drying (105C) caused a marked decrease (average, 54%). A slow decrease in arylsulfatase activity was observed when air‐dried soils were stored at 22–24C.

Arylsulfatase activity decreased markedly with depth in six soil profiles examined. This decrease was associated with a decrease in organic matter content, and studies with surface soils differing markedly in physical and chemical properties showed that soil arylsulfatase activity was significantly correlated with soil organic matter content.

Soil arylsulfatases were not deactivated by most of the reagents used to study the sulfur status of soils.
Soils of Steeply Sloping Landscapes in the Southern Appalachian Mountains
Authors: Losche C. K. , McCracken R. J. , Davey C. B.
Published: July 2010

At two locations in the southern Appalachian Mountains, soils at two slope positions on north‐ and south‐facing landscapes were described, sampled, and analyzed to determine the relative effect of slope aspect and position upon the differentiation of the parent rock into soil profiles. At the southwestern Virginia study area, the parent rocks are highly siliceous sandstone and siltstone, whereas, the parent rock in southwestern North Carolina is a granitic biotite gneiss.

Soils developed from the siliceous parent material were very similar in morphological, physical, chemical, and mineralogical properties irrespective of aspect and slope position. In contrast, there was a high degree of soil profile differentiation at the two slope positions and on the two aspects in North Carolina. In addition to differences in morphological and physical properties, there are distinct differences in the clay mineral suites on opposing aspects. Kaolin and the pedogenic 2:1–2:2 intergrade minerals are predominant in the soils of the north‐facing landscapes, whereas, gibbsite is the major clay mineral in the soils of the south‐facing landscape.
Thin Section Preparation Using an Epoxy Impregnation for Petrographic and Electron Microprobe Analysis
Authors: Innes R. P. , Pluth D. J.
Published: July 2010

Improved apparatus for controlling temperature and pressure during impregnation with the epoxy Scotchcast No. 3 resulted in complete impregnation of high bulk density soil clods. Advantages of the epoxy as a soil impregnating medium were simple preparation, suitable pot life, low viscosity, a 1.53 refractive index, short polymerization period, low relief in polished thin section, and high thermal stability. Technique for transfer of a polished thin section to a circular slide for electron microprobe analysis utilized two thermo‐setting plastics of differing softening points.
Gaseous Loss of Ammonia from Prilled Urea Applied to Slash Pine
Authors: Volk Gaylord M.
Published: July 2010

Gaseous loss of NH3 from prilled urea, surface applied at 100 kg N/ha to undisturbed dry organic residue over moist soil under slash pine (Pinus elliottii Engelm. var. elliottii), averaged 4% in 7 days as compared with 2% for an area that was control‐burned 5 weeks previous, and 5% for one from which loose debris had been removed. This was approximately equivalent to removal by burning. Residual urea recovery of 41% for the burned area as compared with 16 and 12% for the undisturbed and cleaned areas, indicated urease inactivation and partial soil sterilization by burning. Where urea had been applied to moist undisturbed organic residue, hydrolysis approached completion in 3 days and was accompanied by 9% N loss as NH3. Various types and orientations of needle‐bearing portions of branches of slash pine were submitted to a 75–100 cm drop of prilled urea at 100 kg N/ha. From 0.32–0.87 g of pellets were retained per meter of branch. Aspiration tests under typical alternating night and day humidities and native urease activity showed only 3% loss of this retained urea‐N as NH3 in 4 days. At 8 days an average of 52% of the initially retained N was still dilute‐acid soluble from macerated bark plus needle stubs, with a ratio of seven parts urea N to three parts NH4+‐N. The remainder, except for the small gaseous loss, probably was assimilated.
Comparison of Iron and Aluminum Hydroxy Interlayers in Montmorillonite and Vermiculite: I. Formation
Authors: Carstea D. D. , Harward M. E. , Knox E. G.
Published: July 2010

Hydroxy‐Al and ‐Fe interlayers were formed in montmorillonite and vermiculite by adding AlCl3 or FeCl3 and NaOH in amounts to give a wide range of pH. The resulting chloritic intergrades were examined aften 10 days, 6 months, and 1 year.

Aluminum‐interlayered montmorillonite formed at pH 4.6 after 10 days showed the essential X‐ray characteristics of chlorite. The best iron interlayers in montmorillonite prevented collapse upon K‐saturation and heating but did not prevent expansion upon solvation. Aluminum‐interlayered vermiculite showed partial collapse on K‐saturation and heating.

Acid conditions favored interlayer formation with aluminum and iron in montmorillonite and with aluminum in vermiculite. Iron interlayers in vermiculite were favored by alkaline conditions.

Iron interlayers decreased with time. Aluminum interlayers formed in montmorillonite with acid conditions decreased sharply with time. Aluminum interlayers in vermiculite and those formed under alkaline conditions in montmorillonite, showed some tendency to increase with time.
Estimation of Surface Charge Density of Mica and Vermiculite by Competitive Adsorption of Diquat2+ vs. Paraquat2+
Authors: Philen O. D. , Weed S. B. , Weber J. B.
Published: July 2010

Competitive adsorption of diquat2+ (1,1′‐ethylene‐2,2′‐dipyridinium ion) vs. paraquat2+ (1,1′‐dimethyl‐4,4′‐dipyridinium ion) by external surfaces of vermiculite and mica appeared to be linearly related to the surface charge densities of the adsorbents. This suggested a means for estimating surface charge of soil layer silicates. Soil clays, treated for removal of free iron and kaolin, exhibited surface charge densities in the range 7.3–8.7 × 104 esu/cm2.
Clay‐Rich Horizons Over Limestone—Illuvial or Residual?
Authors: Ballagh T. M. , Runge E. C. A.
Published: July 2010

The formation of fine clay horizons over limestone in the soils studied results from illuviation and is not residual material resulting from the dissolution of limestone. This conclusion is reached on the basis of 14C dating of the carbon complexed with the clay, X‐ray diffractograms, and clay size.
Comparison of Methods for Identifying Crystalline Phosphates Produced by Interaction of Orthophosphate Fertilizers with Soils
Authors: Bell L. C. , Black C. A.
Published: July 2010

For identifying crystalline phosphates formed in soils treated with Ca(H2PO4)2·H2O, NH4H2PO4, and (NH4)2HPO4, various methods investigated ranked as follows in decreasing order of sensitivity: optical examination of soil ≥ optical examination of glass‐fiber filter paper inclusion > X‐ray diffraction examination of glass‐fiber filter paper inclusion > X‐ray diffraction examination of soil. Ca8H2(PO4)6·5H2O was identified in one soil but not in the paper inclusion. Differences were more frequent with calcite inclusions. Where there was a difference in phosphates identified between calcite inclusions and calcareous soil, the more acid phosphates seemed more stable in soil than on calcite inclusions, and the more basic phosphates seemed more stable on calcite inclusions than in soil.
Specific Chloride Injury in Persea americana
Authors: Fenn L. B. , Oertli J. J. , Bingham F. T.
Published: July 2010

The mode of chloride injury in avocado plants (Persea americana) was studied at variable Cl levels. The experiment revealed that when leaf burn occurred, it was associated with abnormally high content in total and leachable salt in the leaves. The substantial leachable fraction presumably represents high concentrations of extracellular salt, which accumulates in tips and margins of the leaves after termination of a vigorous growth. In avocado trees, the salt that builds up at the higher substrate Cl levels is associated with what appears to be a mass flow salt movement into conductive tissues causing, possibly, greater salt transport to the leaves than can ultimately be absorbed by leaf cells. The extracellular salt concentrations break down the gradients of osmotic pressure that are necessary to maintain turgor pressure, leading to characteristic tip and marginal necrosis associated with excessive accumulations of Cl. Growth reduction is probably due to energy spent in excessive salt accumulation and loss of photosynthetic area.
Evaluation of Soil Moisture Measurements in Oklahoma as Soil Characteristics for Classification
Authors: Nichols J. D. , Stone J. F.
Published: July 2010

Soil moisture measurements were evaluated as soil moisture characteristics specified in the new soil classification system. Soil moisture measurements were made with a neutron probe at about weekly intervals and were available for 3 to 6‐year periods at four sites with a range in mean annual precipitation of 45 cm to 80 cm. The cumulative days were counted when the soil moisture was below −15 atm pressure in either or both of the 0 to 23‐cm increment and the 23 to 38‐cm increment. The count was also made for the control section of the 23 to 38‐cm increment and the 38 to 53‐cm increment. The data yielded close fitting linear regression lines for cumulative days dry in each year against the measured precipitation for that year. The regression lines for the two tested control sections were nearly alike. The neutron probe method seems to be a satisfactory method for determining days dry. Some adjustment of the data will likely be necessary in translating the data for use in the classification system.
Effects of Different Aqueous Buffers on the Zinc Extractability of Dithizone
Authors: Pietz R. I. , Adams R. S. , MacGregor J. M.
Published: July 2010

The effect of several aqueous buffers on the Zn extractability of dithizone was examined on three Minnesota soils: Zimmerman s, Brainerd sl, and Blue Earth sicl. The five aqueous solutions used with dithizone were water, 1N NH4OAc, 1N NaOAc, 1N Ba(OAc)2, and 1N Ca(OAc)2. Dithizone‐1N NH4OAc extracted the greatest amounts of Zn and dithizone‐water extracted the least. The data indicated that the variation in dithizone extractable Zn with different buffers may be related to the buffering capacity of the aqueous solutions, the NH4 ion, and the soil organic matter present.
Survival of Bacteriophage in Soil “Sterilized” with Gamma Irradiation
Authors: Robinson J. B. , Corke C. T. , Jones D. A.
Published: July 2010

Naturally occurring bacteriophage for Bacillus megaterium strain KM was found to survive in soil following up to 5 megarads of gamma irradiation. While the number of survivors was small, they might nevertheless be a factor in controlling growth of bacteria experimentally introduced into gammasterilized soil.
Fragipans in Pennsylvania Soils: A Statistical Study of Laboratory Data
Authors: Petersen G. W. , Ranney R. W. , Cunningham R. L. , Matelski R. P.
Published: July 2010

Soils sampled for laboratory characterization in Pennsylvania were separated into those profiles with fragipans and those without fragipans to determine statistically the soil properties consistently related to fragipan occurrence. Fragipans occurred in the following five parent material groups: aeolium, fluvium, lacustrine deposits, glacial till, and colluvium. Comparisons were made with horizons from comparable depths from nonfragic soils in these same parent material groups, except for colluvial soils, which in every case contained fragipans. Data were analyzed from 773 samples from 254 soil profiles. Fragipan bulk densities of the <2‐mm material were significantly higher at the 1% level than nonfragipan horizons within till and fluvial parent materials, but were not significantly different within aeolian and lacustrine deposits. Multiple regression analyses using 16 soil variables indicated no relationships between these variables and bulk density. Plots of soil textures showed clustering of fragipan samples in loam and silt loam textural classes, whereas nonfragipan samples were more widely spread over other textural classes. Fragipans had significantly lower organic carbon, lower Ca:Mg ratios, and higher mean base saturations with less alteration of illite to vermiculite than nonfragipan horizons. Chemical and mineralogical data indicate that fragipans are less leached and less weathered than comparable nonfragipan horizons.
Indices for Characterizing Soil‐Water Repellency Based upon Contact Angle‐Surface Tension Relationships
Authors: Watson C. L. , Letey J.
Published: July 2010

The relation between apparent liquid‐solid contact angle and surface tension was established for three water repellent materials using both a series of aqueous ethanol solutions and organic liquids. The media included two artificially treated sands and one naturally occurring soil. With one exception there was an approximate linear relationship between the cosine of the contact angle and the surface tension. The relationship for the forest soil tended to be curvilinear when using ethanol solutions of high surface tension. The repellency of the materials was best differentiated by using their intercepts with cos θ = 0. A simple drop test using the same materials and ethanol solutions placed the materials in the same order of repellency. The drop test was further developed to allow classification of porous media on the basis of (i) 90° surface tension (γn), and (ii) stability to water interaction. The tests can be readily performed both in the laboratory and the field. Two indices were then proposed to describe water‐repellent characteristies of soils. These indices will be valuable in assessing erosion and runoff problems, and also the feasibility of surfactants to promote infiltration.
Simulation of Heat Transfer in Soils
Authors: Wierenga P. J. , de Wit C. T.
Published: July 2010

A computer model was developed to predict the temperature fluctuation in subsoil from the temperature variation at the soil surface, taking into account changes in the apparent thermal conductivity with depth below soil surface and soil temperature. The model makes use of S/360 CSMP, a recently developed simulation language for digital computers. Predicted soil temperatures were compared with soil temperatures observed at 2, 10, 15, 25, 30, and 75 cm below the surface of bare field profiles, before and after irrigation with 13.4 cm water. In wet soil observed and predicted temperatures were in close agreement. In dry soil significant differences were observed between measured and predicted soil temperatures during part of the day. The increase in apparent thermal conductivity with soil temperature had a negative effect on the magnitude of the difference between observed and predicted values in the dry soil. Agreement was found between soil heat flux density values predicted from the model and calculated with the temperature integral method. Use of a digital simulation language can save considerable programming time, and can be applied to movement of water and gases in soil profiles.
A Mathematical Solution to a Hillside Seepage Problem
Authors: Warrick A. W.
Published: July 2010

A solution is presented for a two‐dimensional hillside seepage problem. The soil is assumed to be water‐saturated to the soil surface where the soil water is at atmospheric pressure. Seepage occurs into the flow medium along the upper part and out along the lower part of the sloping soil surface. The flow medium is infinitely deep and bounded laterally by vertical stream‐lines. Conformal transformations are used to find the hydraulic head and stream functions. Although the solution is analytic, a complex integral must be evaluated numerically for application. Numerical data presented includes flownets, seepage velocities, infiltration angles, and volume of flow as a function of slope.
The Diffusion of Copper, Manganese, and Zinc as Affected by Concentration, Clay Mineralogy, and Associated Anions
Authors: Ellis J. H. , Barnhisel R. I. , Phillips R. E.
Published: July 2010

The distributions of Cu2+, Mn2+, and Zn2+ diffusing in thin oriented clay films of water‐saturated montmorillonite, vermiculite, illite and kaolinite were obtained using a miniature probe attachment for an x‐ray emission spectrometer. Diffusion coefficients were calculated from these experimental distributions. Only small differences in the diffusion coefficients of Cu2+, Mn2+, and Zn2+ at comparable concentrations were found for a given clay. The range of diffusion coefficients for CuCl2 was 1.7 × 10‐7 cm2 sec‐1 at 0.01 meq/g of vermiculite clay to 52.1 × 10‐7 cm2 sec‐1 at 0.5 meq/g of kaolinite. The diffusion rates of copper, manganese, and zinc through the clay minerals were of the order: kaolinite > illite > montmorillonite >vermiculite. Some estimates of the diffusion coefficients in the liquid phase and in the adsorbed phase are given. The anions, Cl‐, NO3‐, SO42‐, and OAc‐ when diffusing with the cupric ion affected its diffusion rate. The order of diffusion coefficients at a concentration of 0.5 meq/g of montmorillonite clay were: CuCl2 > Cu(NO3)2 > CuSO4 > Cu(OAc)2; the respective diffusion coefficients were: 9.5, 8.3, 6.9, 2.7 × 10‐7 cm2 sec‐1.
Nitrous Oxide Formation by Nitrosomonas Europaea and Heterotrophie Microorganisms
Authors: Yoshida T. , Alexander M.
Published: July 2010

Nitrosomonas europaea oxidizes ammonium to nitrous oxide, a reaction that is enhanced by storing the bacteria at low temperature and by phosphate and high pH. Nitrous oxide is also formed from hydroxylamine by the autotroph. Nitrous oxide is apparently generated from an intermediate in nitrification, and the data suggest that the conversion of this intermediate to nitrite is inhibited by ammonium, hydrazine, or high temperature. Nitrous oxide is also formed during nitrate reduction by Bacillus subtilis, Escherichia coli, and Aerobacter aerogenes and during nitrite reduction by Aspergillus flavus and Penicillium atrocenetum. It is suggested that the production of nitrous oxide by the autotrophic nitrifier, Nitrosomonas, and by such heterotrophic organisms may be of biogeochemical importance.
Pedogenic Distribution of Zinc in Mollisols and Associated Entisols in Nebraska
Authors: Dankert Wayne N. , Drew James V.
Published: July 2010

The distribution of total Zn in a Udie Haplustoll (Moody) and a Typic Argiustoll (Holdrege) formed in Peoria loess in Nebraska is related to the accumulation of illuvial clay in these soils. In Typic Ustorthents (Crofton and Coly) formed in Peoria loess, a comparable distribution of noncarbonate clay and total Zn does not occur. Larger amounts of Zn in noncarbonate clay from the upper sola of the four profiles than in noncarbonate clay from their C horizons suggest that Zn is released from soil minerals and cycled by vegetation during biopedogenic weathering, then becomes associated with noncarbonate clay in the A horizons following decomposition of plant residues. In Moody and Holdrege, however, maximum amounts of Zn in the total soil occur in the B horizons of clay maxima, suggesting that Zn moves in association with clay from the A to the B horizons during the genesis of these soils.
Free Iron Oxides: Rapid Determination Utilizing X‐ray Spectroscopy to Determine Iron in Solution
Authors: Fanning D. S. , Korcak R. F. , Coffman C. B.
Published: July 2010

X‐ray spectroscopy is a convenient and rapid way of measuring iron in solution, especially employing the inverted type spectrographs and cells sealed with mylar film for presenting the liquid in the spectrograph. These techniques were adapted to measuring free iron extracted by the citrate‐bicarbonate‐dithionite method and could easily be adapted to measuring iron in other extractants. The spectrograph is sensitive to iron over a range of several thousand µg/ml and gives a linear response up to at least 500 µg/ml. Colorimetric methods are only sensitive in the 0 to 4 µg/ml and atomic absorption is normally used over a 0 to 20 µg/ml range. Thus extracts normally must be diluted for colorimetric or atomic absorption, but not for x‐ray spectrographic, iron determination. Also the oxidation state of the iron is critical with colorimetric or titrimetric iron determination, but not with the x‐ray method. Determinations on the same extracts by Hsu's thiocyanate colorimetric method for soils representing a range of free iron contents.
208Tl and 24Na Gamma Sources for Identifying Soil Water Tagged with Deuterium
Authors: Hawkins R. H. , Overman R. F. , Corey J. C.
Published: July 2010

In situ tracing of soil water movement with the D2O‐24Na method has been limited by the need to reactivate the 24Na gamma source frequently (half‐life of 15 hours) in a nuclear reactor. Our laboratory study showed 208Tl produced the same neutron count rates from vials of D2O in dry and moist soil as did 24Na. The 1.9‐year effective half‐life of 208Tl in equilibrium with its parent nuclide 228Th is a significant advantage of 208Tl over 24Na. Recent commercial availability of 208Tl sources now makes in situ D2O tracing of soil water feasible for investigators not having access to a nuclear reactor.
Toxic Metals in Acid Soil: II. Estimation of Plant‐Available Manganese
Authors: Hoyt Paul B. , Nyborg Marvin
Published: July 2010

Manganese in 40 acid surface soils was measured by eight methods and statistically compared with the concentrations of Mn in barley (Hordeum vulgare L.), turnip rape (Brassica campestris L.), and alfalfa (Medicago sativa L.) grown on the soils in a greenhouse study. Of the eight methods, a 16‐hr extraction with 0.01M CaCl2 gave by far the best estimate of plant‐available Mn, the correlation coefficients being 0.76, 0.73, and 0.86 between Mn extracted from the soil and the concentrations of Mn in barley, rape, and alfalfa, respectively. Another form of soluble Mn, that extracted by 0.1N HOAc, gave the next best estimate of plant‐available Mn. The other five extraction methods, consisting of 0.1N H3PO4 or 0.002N HCl for soluble Mn, 1N KCl or 1N NH4OAc (pH 3) for exchangeable Mn, and 0.2% hydroquinone in 1N NH4OAc (pH 7) for easily reducible Mn, gave fair to poor estimates of available Mn. Total Mn gave a poorer estimate than did any of the methods used for extractable Mn. On arranging the soils in two groups of equal number, having pH ranges of 4.15–5.14 and 5.15–5.63, good measurements of available Mn in both groups were given by only the 0.01M CaCl2 method.

Manganese in the three plant species was correlated with soil pH but not with percent base saturation. Besides being related negatively to soil pH, Mn in the plants also was related positively to total soil Mn and negatively to soil exchange capacity as shown by multiple regression analyses.
s‐Triazine Adsorption Studies: Ca‐H‐Humic Acid
Authors: Gilmour J. T. , Coleman N. T.
Published: July 2010

Small amounts of Ca‐H‐humic acid suspension in dialysis bags were immersed in dilute CaCl2 which contained 1.33 × 10‐5M to 6.67 × 10‐5M atratone, atrazine, prometone, or prometryne. Adsorption isotherms were linear. Increases in CaCl2 concentration from 10‐4M to 10‐2M or larger Ca saturation (10 to 100% Ca) of humic acid resulted in less s‐triazine adsorption. Greater adsorption occurred when the amount of Ca‐humate at a specified Ca saturation was increased. An ionexchange treatment of adsorption quantitatively predicted adsorption changes with change in s‐triazine concentration, CaCl2 concentration, and Ca saturation of the humic acids.
The Cause of the Suspension Effect in Resin‐water Systems
Authors: Olsen R. A. , Robbins J. E.
Published: July 2010

Two hypotheses persist regarding the cause of the suspension effect. The traditional hypothesis attributes the effect to a different activity of ions in the suspension than in the dialyzate. The alternative hypothesis attributes the effect largely to a junction potential at the calomel‐suspension boundary. Data obtained by means of three independent methods in this investigation indicate that the latter hypothesis is correct. A potentiometric technique indicated that activities of chloride ions cannot be reliably measured directly in resin‐water systems due to the uncertainty of a junction potential which may be negligibly small or may be as high as several hundred millivolts. Osmotic pressure and freezing point determinations provided confirmatory evidence that the activity of ions was virtually identical in slurry and dialyzate even though the suspension effect was exceptionally large.
Effect of Ammonium and Nitrate Fertilization on Phosphorus Uptake as Related to Root‐Induced pH Changes at the Root‐Soil Interface
Authors: Riley D. , Barber S. A.
Published: July 2010

Soybeans (Glycine max L.) fertilized with either NH4‐N or NO3‐N were grown in a growth chamber using soil with four different initial pH levels. Liming the soil used in this research to increase pH decreased the P level in solution. Fertilization of soybeans with NH4‐N decreased the pH of the rhizocylinder (root plus strongly adhering soil); fertilization with NO3‐ increased rhizocylinder pH. The difference between the rhizocylinder pH of the NH4+ and NO3‐ treatments was as large as 1.9 pH units with an initial soil pH of 5.2 and as small as 0.2 units when soil pH prior to N application was 7.8.

Ammonium‐fertilized soybeans absorbed more P and had a higher P concentration than NO3‐fertilized soybeans. The results for soybeans grown with NH4+ and NO3‐ treatments at four initial soil pH levels showed that the P content of the shoots and roots was closely correlated with the pH of the rhizocylinder, but not the pH of the bulk soil. This suggests that the increased availability of P from the soil where NH4+ was used was mainly due to the effect of the nitrogen source on the pH of the rhizosphere soil.

Soybean root length decreased from 180 to 120 m/gram of dry roots as the pH of the rhizocylinder increased from 4.7 to 7.5.
Factor Analysis and Numerical Taxonomy of Soils
Authors: Arkley Rodney J.
Published: July 2010

A large computer and multivariate statistics were used to select a minimal number of soil properties with the greatest prediction value for use in soil classification. Key communality cluster analysis and principal axis factor analysis with Varimax rotation were applied to six sets of soil data containing from 21 to 66 profile characteristics. The analyses selected from four to seven factors or dimensions which were highly independent of each other and contained from two to four highly correlated soil properties. These factors accounted for 100% of the communality and 90% of the raw variance in all properties used in each set. In spite of the diversity of the soils (220 and 620 California, 59 and 86 World, and 148 Ohio soils) the same factors appeared repeatedly; i.e., properties related to reaction, hue and chroma, texture, color value and mottling, and profile differentiation in five analyses and solum thickness in four. Composite factor scores computed for each soil were also used for Numerical Taxonomy. The groupings formed were sufficiently similar to those of the New Classification System of the USDA to suggest that these methods may be very useful in soil classification. The use of these methods for the development of a coordinate system of soil classification is discussed.
Water‐soluble NO3‐Nitrogen, PO4‐Phosphorus, and Total Salt Balances on a Large Irrigation Tract
Authors: Carter D. L. , Bondurant J. A. , Robbins C. W.
Published: July 2010

Return flow from a 82,030‐ha (202,700‐acre) tract of calcareous silt loam soils irrigated with water diverted from the Snake River in southern Idaho increased the downstream total soluble salt and NO3‐N loads, but decreased the downstream PO4‐P load. Under the existing water management practice, 50% of the total input water returned to the Snake River as subsurface drainage. Net total soluble salt output was 2.4 metric tons/ha (1.0 English ton/acre) and, on the average, was considerably greater than necessary to maintain a salt balance. Net NO3‐N output was 33 kg/ha (30 lb/acre). Only about 30% as much PO4‐P left the tract via drainage water as entered the tract in irrigation water. As water passed through the soil, PO4‐P was removed by chemical reactions in the soil, thus decreasing the concentration in the subsurface drainage water and decreasing the downstream PO4‐P load. Applied P fertilizer was not leached into the drainage water.