bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidation of Liquid Animal Wastes in Soil
Authors: Kowalik P. , Barnes C. J. , Smiles D. E.
Published: July 2010

A theory of oxygen diffusion in soil in which the oxygen consumption rates varies with time was applied to describe the oxidation of liquid animal wastes in a soil irrigated by a slurry of pig manure. Soil column experiments with a pig slurry of known biochemical oxygen demand (BOD) showed that the aerobic return of the soil atmosphere composition to that approaching air is described by analytical solutions of the diffusion equation with a time‐dependent sink term. The aerobic and anaerobic zones can be determined in the soil profile according to the solutions given for the transient state in two cases: (i) when uptake of oxygen is uniformly distributed over the soil profile; and (ii) when uptake of oxygen is limited to the upper part of the soil profile. These solutions may be used to determine maximum BOD loads for soils irrigated by waste water with relatively high organic content.
Phosphorus Response of Corn on an Oxisol as Influenced by Rates and Placement
Authors: Yost R. S. , Kamprath E. J. , Lobato E. , Naderman G.
Published: July 2010

Phosphorus deficiency and high P sorbing capacities are a major limitation to intensive cropping of many soils in the Cerrado area of Central Brazil. A field study comparing rates and placement of P for corn (Zea may L.) was conducted to determine initial and long‐term P fertilization requirements. Rates of broadcast P were 70, 140, 280, and 560 kg P/ha and banded rates were 35, 70, and 140 kg P/ha. In addition, combination treatments of 140 or 35 kg P/ha broadcast and banded rates of 35 kg/ha per crop were used.

Broadcast treatments gave greater yields than band treatments at the same rates for the first crop. At the end of four crops, however, total yields and P uptake were very similar for broadcast and band treatments in which the same total amount of P had been applied. Marked residual effects were observed with the higher rates of broadcast P.

A greenhouse study was conducted in which a given amount of P was mixed with varying proportions of the total soil volume. Corn growth and P uptake were a function of both the concentration of P in the portion of the soil fertilized and the percent of the total soil volume that was fertilized. These results tend to explain the increase with time in relative yields of the banded treatments.

The best method for applying P to these high adsorbing soils appears to be an initial broadcast application of 140 kg P/ha and a band application of 35 kg P/ha to each crop. This treatment maintained the available soil P at the critical soil test level and produced 80 to 85% of the maximum yield.
Estimating Animal Waste Applications to Supply Crop Nitrogen Requirements
Authors: Mathers A. C. , Goss D. W.
Published: July 2010

An equation was developed which estimates the amount of animal waste required to supply the desired amount of N for crops. This equation was based on annual mineralization rates which varied with time after application and with N content of the waste. When we calculated waste requirements to supply N needs using the equation, values were satisfactory for wastes containing 4% or less N. Residual N in soil fertilized with animal waste was closely correlated (r = 0.92) with values predicted by the equation.
An Aberrant Toposequence of Soils through a Titi Swamp
Authors: Coultas C. L. , Clewell A. F. , Taylor E. M.
Published: July 2010

Three Great Groups of soil, Humaquepts, Haplaquods, and Psammaquents, were found on a traverse through a titi swamp in north Florida. The Humaquept occurred in the lowest, wettest position and plants of Cyrilla racemiflora L. and Nyssa biflora Walt, were largely restricted to these soils. These soils were extremely acid, low in extractable bases, well supplied with organic C, and highest in clay content. Haplaquods occurred in a higher position with better drainage. On these soils vegetation included Cliftonia monophylla (Lam.) Sarg., Magnolia virginiana L. and Myrica inodora Bartr. inside the titi swamp, and outside the swamp, species common to the pine flatwoods. These Haplaquods were acid and low in extractable bases. They contained less organic C and clay than the Humaquept. The Psammaquents were the best drained due to their high position and coarse texture. They contained the least organic C.

Evidence is presented which indicates that the titi swamp has encroached into areas formerly vegetated with pine flatwoods. This was probably due to recent fire control and wetter soil conditions.
Water Use and Yields of Sugarbeets Over a Range from Excessive to Limited Irrigation
Authors: Ehlig C. F. , LeMert R. D.
Published: July 2010

Water use and sucrose yield of sugarbeets (Beta vulgaris L. cv. USH 10) as a function of decreasing water applications were investigated to determine if sucrose yield per unit of water use would increase with limited irrigation. The sugarbeets were fall‐planted in a silty clay soil and irrigated uniformly for 6 weeks to establish seedling stands and to wet soil to the 152‐cm depth. Thereafter, 102 mm water was applied whenever cumulative ET from sugarbeets growing in an adequately watered weighing lysimeter reached 91, 102, 112, 122, 133, or 143 mm water. Soil was sampled to the 152‐cm depth, in 30.5‐cm increments, before each irrigation after 12 November and at harvest. Water use was calculated from changes in soil water content between irrigations and applied water.

Water applications, after the initial uniform applications, varied from 609 to 940 mm in six to nine irrigations plus 25 mm rainfall. Water use was linearly related to lysimeter ET. During differential treatment, water use varied from 11% above to 23% below the amount needed to replace lysimeter ET. Total seasonal water use varied from 900 to 1,195 mm. Lysimeter ET averaged 67% of pan evaporation after leaves completely covered the soil. Neither sucrose content nor yield was affected by irrigation treatments. Sucrose yields averaged 13 and 18 metric tons/ha on 14 May and 24 June, respectively. With limited irrigation, sucrose yield per unit of water use increased as much as 22% above the treatment that matched lysimeter ET. The soil salinity did not increase sufficiently to require immediate leaching for any of the treatments.
Factors Affecting Nitrate Nitrogen and Chloride Leaching Variability in a Field Plot
Authors: Cameron D. R. , Kowalenko C. G. , Campbell C. A.
Published: July 2010

Nitrate nitrogen and chloride concentrations were monitored in a 3‐year field study in order to examine factors affecting their variability. Fertilized and control plots, established each year, were sampled at least eight times throughout the year by removing about six‐replicate soil cores for individual analyses each sampling time. It was found that non‐uniform fertilization application accounted for 38 to 100% of the sampling variability immediately after fertilization. In fall and spring, differential rates of leaching of NO3‐N and Cl appeared to contribute significantly to variability increasing C.V.'s from about 40% to over 100%. Field and model results showed that differential leaching patterns could be attributed to two main factors: (i) variability of physical properties that determine water storage and transport, and (ii) point differences in redistribution of incoming rain (runoff) due to differences in surface microrelief.
Effects of Burning on Chaparral Soils: II. Soil Microbes and Nitrogen Mineralization
Authors: Dunn Paul H. , DeBano Leonard F. , Eberlein Gary E.
Published: July 2010

Undisturbed moist and dry soil slabs collected from beneath two species of chaparral plants were burned at varying intensities in the laboratory. Treatment by intense burning over dry soil destroyed 67% of the total N and produced large amounts of NH4+. Treatment by intense and moderate burning over moist soil slabs removed only 25% of the total N, and a large portion of the remaining organic N was quickly ammonified after the fire by reinvading heterotrophic bacteria and later by fungi. All three burning treatments resulted in high levels of NH4+ in the soil after the fire. Nitrosomonas group bacteria did not respond to these high levels of available NH4+, and the nitrification that occurred was attributed to heterotrophic nitrification.
Tolerance of Rhizobia to Acidity, Aluminum, and Phosphate
Authors: Keyser H. H. , Munns D. N.
Published: July 2010

Low levels of phosphorus and high levels of aluminum are important soil acidity factors for the growth of higher plants; however, very little is known about their effects on the soil rhizobia. The present study was conducted to determine the relative effects of acidity, P, and Al on rhizobia. Tolerance of low pH (4.5), low P (5–10 µM), and high Al (50 µM) was assessed for 10 strains of cowpea rhizobia by detailed growth studies in defined liquid media. Tolerances to these factors were determined for 65 strains of cowpea rhizobia and Rhizobium japonicum by a rapid method based on attainment of turbidity from a small inoculum. Strains varied in response. Low P (as compared with 1,000 µM) limited total attainable population density to 5 × 107 cells/ml, and slowed the growth of some strains. Acidity generally increased lag time or slowed growth of most strains, and stopped growth of about 50% of them. Tolerance of acidity did not necessarily entail tolerance of Al. Aluminum (50 µM) increased the lag time or slowed growth of almost all strains tolerant of low pH. It virtually stopped growth of 40% of the strains.

With our system the rhizobia had to make 1,000‐fold growth in the stress media before they could significantly raise pH and precipitate Al. A valid rapid screening can be based on ability to attain visible turbidity in culture under acid or Alstress, so long as initial density is small (<<105 cells/ml). The cowpea rhizobia tended to have more tolerance to Al than R. japonicum and overall Al was a more severe stress than low pH or low P.
Growth, Water Relations, and Yield of Wheat Planted in Four Row Directions
Authors: Erickson P. I. , Kirkham M. B. , Stone J. F.
Published: July 2010

Wheat (Triticum aestivum L. em. Thell. ‘Osage’) was planted in north‐south, northwest‐southeast, east‐west, and southwest‐northeast directions, using a wheel layout, to determine the effect of row orientation on height, leaf water potential, stomatal resistance, and yield of winter wheat exposed to the normally strong north and south winds of central Oklahoma.

Before plants started to grow rapidly in the spring, wheat in north‐south rows was about 1 cm taller than wheat in the other row directions. After plants started to grow rapidly, wheat in north‐south rows was 2‐ to 6‐cm taller than wheat in the other rows. Leaf water potentials of wheat oriented in north‐south rows were, on an average throughout the spring of the experiment, 2.8, 2.9, and 2.1 bars higher (less negative) than potentials of leaves oriented in other rows for 1000‐, 1300‐, and 1600‐hour readings, respectively. Stomatal resistances of leaves of wheat oriented in north‐south rows were, on an average throughout the spring of the experiment, 0.2, 0.7, and 0.2 sec/cm lower than those of leaves oriented in other row directions for the 1000‐, 1300‐, and 1600‐hour readings, respectively. The east‐west plantings had about a 10% higher yield than the north‐south rows.
An Error Analysis of the Photographic Technique for Measuring Percent Vegetative Cover
Authors: Lee Williams T. H.
Published: July 2010

A vertical overhead ground photographic technique was developed to determine percent vegetative ground cover. Acquisition of the photographs is rapid and simple and the technique is well suited to situations where simplicity and speed in the field are necessary. A vegetative canopy model was used to derive a measure of the errors inherent in the technique. The degree of error is related to the canopy structure and is at a minimum in dense canopies.
Comparative Performance of Nitrogen Sources on Smooth Bromegrass and Tall Fescue
Authors: Lamond R. E. , Murphy L. S. , Swallow C. W. , Kelley K. W.
Published: July 2010

Studies were initiated in 1973 at two locations in eastern Kansas to evaluate the performance of five N carriers as sources of N for bromegrass (Bromus inermis L.) and tall fescue (Festuca arundinacea Schred.). Late winter applications of ammonium nitrate, urea, urea‐ammonium nitrate solution (UAN), sulfur‐coated urea (SCU), and urea‐ammonium sulfate (UAS) were compared at rates of 67, 134, and 201 kg N/ha.

Excellent visual responses to applied N were evident in both years. Total yields of forage generally increased with N applications up to 201 kg N/ha. The response to N decreased as the rate was raised from 134 to 201 kg N/ha. Maximum economic return from the application of N occurred at a level of about 134 kg N/ha. No clear‐cut superiority was established for any N carrier. Sulfur‐coated urea performed well on tall fescue but less effectively on bromegrass. Although there was evidence of delayed release of N from SCU, its efficiency as measured by total yield was similar to conventional N sources. The effectiveness of a carrier was influenced by location, environmental conditions, and grass species.
Chemisorption and Precipitation of Mn2+ at CaCO3 Surfaces
Authors: McBride M. B.
Published: July 2010

The adsorption of Mn2+ on two samples of powdered calcite with different surface areas has been studied using atomic absorption and electron spin resonance spectroscopy to investigate the solution and mineral phases. Chemisorption of Mn2+ on CaCO3 surfaces lowered the solubility of Mn2+ below the level expected for MnCO3 precipitation. At high levels of Mn2+ in solution, after saturation of surface sites, nucleation at CaCO3 surfaces seemed to occur, followed by slow precipitation of separate phase MnCO3. The preference of calcite for Mn2+ relative to Ca2+ decreased with increasing Mn2+ absorption. The results indicate the importance of the surface area of the solid phase in determining the quantity of Mn2+ adsorbed and the final solution concentration.
Methods for the Production and Use of Nitrogen‐13 In Studies of Denitrification
Authors: Tiedje J. M. , Firestone R. B. , Firestone M. K. , Betlach M. R. , Smith M. S. , Caskey W. H.
Published: July 2010

Methods were developed for use of the radioactive isotope of nitrogen, 13N, for short‐term studies of denitrification. 13N was generated by irradiation of water with 12 to 15 MeV proton beams from a sector‐focused cyclotron. Under typical operating conditions of 0.7 to 3 µA beam currents for 10 min, the 13N ionic species produced were NO3‐, 75–90%; NO2‐, 5–10% and NH4+, 0.5–25%. Traces of [13N] N2O and [13N] N2 were also produced. The measured yield varied from 2 to 16 mCi/10 min irradiation depending on beam current. Vacuum evaporation at high pH was used to obtain 13NO3‐ + 13NO2‐ at > 99.8% purity, and high performance liquid chromatography (HPLC) was used to obtain 13NO3‐ or 13NO2‐ at > 99% purity. The HPLC system used a Partisil SAX anion exchange column eluted with phosphate buffer at pH 3.0 and was coupled to a coincidence NaI(T1) detector for counting 13N species in the effluent. Separation of NH4+, NO2‐, and NO3‐ was achieved within 5 min. This system was used to monitor purity of 13N substrates and for studies of dissimilatory nitrate reduction to ammonia. A gas chromatograph‐proportional counter detector system was developed to separate and measure [13N] N2, [13N] N2O and 13NO. Separation was by Poropak Q and Molecular Sieve 5A columns and was achieved in 5 min. Denitrification rates and products of soils and bacterial cultures incubated in sealed flasks were monitored with this system. Continuous rates of [13N] N2 and [13N] N2O production were monitored using a differential trapping, gas stripping system. Soil slurries amended with 13NO3‐ or 13NO2‐ were stripped of gases by continuously sparging with helium. N2O was collected in a liquid nitrogen trap. Nitrogen gas passed through this trap but was retained in a Molecular Sieve trap immersed in liquid nitrogen. 13N gases collected in each trap were continuously counted by NaI (T1) detectors. Linear rates of gas production were typically observed from 15 min after addition of the 13N substrate to termination of the experiment after 1 to 1.5 hours. 13N has the advantage in denitrification studies of allowing direct measurement of N2, very sensitive short‐term rate measurements, and isotope exchange experiments at low substrate concentrations.
Asynchronous Activity of Ammonium Oxidizer Clusters in Soil
Authors: Molina J. A. E. , Gerard G. , Mignolet R.
Published: July 2010

Ammonium oxidation by 468 large (0.49 mg) and 416 small (0.12 mg) soil aggregates from an Ochric Epipedon was determined by the Winogradsky silica gel‐CaCO3 plate technique. Activity was spread over 8 weeks. The histogram for the percentage of active soil aggregates presented a maximum after 3 to 4 weeks of incubation. Only 48 and 22% of the large and small aggregates oxidized ammonium, which corresponded to an average of 0.65 and 0.34 clusters of activity per large and small aggregates, respectively. On the average, each cluster in the large and small aggregates harbored 31 and 14 ammonium oxidizer cells, as computed from the MPN values for the ammonium oxidizer cells per g of soil. Enrichment of the soil by preincubation for 8 weeks after the addition of 100 ppm NH4+ induced for the large and small aggregates a 1.5‐ and 1.4‐fold increase in the number of clusters but a 4.6‐ and 4.8‐fold increase in the number of ammonium oxidizer cells per cluster.

The results indicate that the kinetics of ammonium oxidation in soil, for the nonsteady state situation, represents the resultant average of pulses of activity from small isolated and asynchronous ammonium oxidizer clusters, in contrast with present models which assume one homogenous, synchronous population of ammonium oxidizer cells in soil.
Mössbauer Studies of Synthetic and Soil‐Occurring Aluminum‐Substituted Goethites
Authors: Golden D. C. , Bowen L. H. , Weed S. B. , Bigham J. M.
Published: July 2010

Mössbauer spectroscopy of partially Al‐substituted synthetic goethites shows marked variation of the internal magnetic field (H) with Al substitution. Empirical relations are reported which allow using observed H values to estimate % Al in the oxides present in soil clay. Relaxation effects due to small particle size and substitution of Al3+ for Fe3+ complicate the spectra, and in many cases liquid nitrogen or liquid helium temperatures are necessary to resolve the components. However, the relaxation effects observed may be related qualitatively to particle size of the Fe oxides present. The utility of the Mössbauer technique was tested with a number of soil samples containing Al‐substituted goethite.
Ion Exchange Equilibria Involving Aluminum in a Kaolinitic Ultisol
Authors: Pleysier J. L. , Juo A. S. R. , Herbillon A. J.
Published: July 2010

Cation exchange equilibria in an acid Ultisol profile involving K‐Al, Ca‐Al, K‐Ca, Na‐K, and Na‐Ca exchanges were studied. Selectivity coefficients, surface activity coefficients and free energy changes were computed using the thermodynamic formulations.

In exchange equilibria involving Al, the magnitude of selectivity coefficients Kc, was affected by pH, surface composition, and hydrolysis of Al. In equilibria not involving Al, good reversibility for K‐Ca, Na‐K and Na‐Ca exchanges was obtained. Potassium was selectively adsorbed in all horizons of the profile. The over‐all selectively sequence follows the order of K>Al>Ca≈Na.
Infrared Spectra of Sewage Sludge Fractions: Evidence for an Amide Metal Binding Site
Authors: Boyd S. A. , Sommers L. E. , Nelson D. W.
Published: July 2010

Infrared studies were conducted to qualitatively characterize sewage sludge light (organic) and heavy (inorganic) fractions obtained using a heavy liquid separation technique. Infrared spectra of sludge organic fractions revealed the presence of proteinaceous and polysaccharide‐like materials. Infrared absorptions characteristic of carboxyl groups and aromatic compounds were not observed in the spectra of sludge light fractions. The position of the amide‐I band in the infrared spectra of the sludge light fractions was used to obtain direct evidence of metal binding sites involving amide N and possibly amide O. A discrete shift in the position of the amide‐I band was initiated by extracting indigenous metal cations from the sludge organic fraction. This shift was reversed by saturating the extracted sludge organic fraction with Cu2+. Absorption bands of quartz and calcite dominated the infrared spectra of sludge inorganic fractions.
Characterization of Zinc Adsorption in Some Soils of India
Authors: Shukla U. C. , Mittal S. B.
Published: July 2010

Laboratory studies were conducted to characterize Zn adsorption in some soils varying in texture using a wide range of equilibrating Zn concentrations. The fit of adsorption data was tested both in Freundlich and Langmuir isotherms. The Langmuir isotherm was resolved into two linear portions. Binding energy coefficients (K) were higher and adsorption maxima (b) were lower in part I than part II of the curves for both soils. b values were higher and K values were lower for loam than sand. The Freundlich isotherm was also resolved into three distinct portions having different K and n values. The adsorption pattern at different concentrations indicated differential bonding energies for adsorbed Zn, and occurrence of precipitation reactions along with adsorption in these soils, even before saturation of cation exchange capacity (CEC). The results showed the limitations in describing Zn adsorption through Langmuir or Freundlich adsorption isotherms in such soils of pH ⩾ 8 at 6 ppm Zn concentrations due to precipitation. Zinc adsorption exceeded CEC at equilibrating Zn concentration of 10−2M. The soil texture did not affect the nature of adsorption curves but more Zn was adsorbed by loam than sand showing the effect of the number of adsorption sites.
Relationship of Antibiotic Resistance to Effectiveness in Rhizobium trifolii Populations
Authors: Hagedorn C.
Published: July 2010

Fifty Rhizobium trifolii isolates were divided into five categories of symbiotic effectiveness and examined for resistance to 15 antibiotics. The cultures were resistant to high concentrations of 11 of the antibiotics but were relatively sensitive to chloramphenicol, streptomycin, tetracycline, and vancomycin. Resistance to any particular group of antibiotics was not associated with any one of the different categories of effectiveness but rather was equally dispersed between all categories. Eighteen isolates which differed in effectiveness were used to develop subcultures resistant to 3× or 4× the average minimum inhibitory concentration (MIC) of the parent strains for each of the antibiotics. Reduction in effectiveness was found in 12.5% of the resistance strains, was not associated with any particular antibiotic, and was randomly distributed throughout the five effectiveness categories. Increased effectiveness occurred with only three subcultures (2.5% of the tests). Cross‐resistance patterns were generally restricted to those antibiotics which expressed similar modes of activity and the development of cross‐resistance occurred in 5.7% of the possible resistance combinations. Results presented in this study do not agree with other reports in which antibiotics were divided into groups based on their association with effectiveness.
Effect of Soil Nutrient Status and pH on Nitrogen‐Fixing Algae in Flooded Soils
Authors: Wilson J. T. , Alexander M.
Published: July 2010

The development of indigenous N2‐fixing algae in 10 of 12 flooded soils, as measured by acetylene‐reduction activity, was stimulated by the addition of phosphate. In P‐supplemented flooded soils, these algae generally developed readily at pH 7.3 or greater but poorly at pH 6.5 or less. Iron additions stimulated the activity of inoculated blue‐green algae in a phosphate‐amended flooded soil of pH 7.9 but not in a soil with a pH of 5.5. Indigenous algae in an acid soil (pH 4.8) were stimulated by CO2. Nitrogen fixation and development of indigenous blue‐green algae were correlated with pH and the levels of extractable K and of Ca and Mg in these soils, but not with the concentrations of organic matter, inorganic N, or extractable phosphate and Fe.
Soil‐Geomorphic Relationships in Postglacial Alluvium in New York
Authors: Scully R. W. , Arnold R. W.
Published: July 2010

In south‐central New York alluvial soils of the three postglacial geomorphic units were correlative between two sites on different size rivers. Noncumulative Inceptisols dominate the higher postglacial terrace. Cumulative soils, with buried A horizons, that are fluventic subgroups of Inceptisols have developed in overbank silts episodically deposited during the past 3,500 years on the lower terrace (high bottom). Significantly less developed soils, but sometimes taxonomically identical, have developed in the oldest portion of the flood plain (low bottom). Weakly structured soils dominate the younger alluvial fills of the flood plain whose sandy lateral accretion deposits are less than 880 ± 130 years B.P. old. The weakly structured soils have remnants of textural stratification and lack color evidence of alteration and are presumably Fluvents.
pH‐Dependent Zinc Adsorption by Soils
Authors: Bar‐Yosef B.
Published: July 2010

There is a need for a simple equation relating the adsorption of Zn to its solution concentration and pH. Such an equation was derived using the competitive Langmuir adsorption isotherm. Experimental results obtained for five different soils in batch experiments were compared with results computed for each soil according to fitted parameters. Three criteria for the adequacy of the equation were tested: an acid titration curve in the absence of Zn, Zn adsorption as a function of its solution concentration at a given pH, and Zn solution concentration at a fixed total amount of Zn as a function of pH. Close agreement between calculated and experimental results was obtained for the analyzed soils in all tests.
Reclamation of Saline‐Sodic Soils by Leaching
Authors: Jury W. A. , Jarrell W. M. , Devitt D.
Published: July 2010

Seven lysimeters containing sandy loam or clay loam soils were reclaimed by ponded or unsaturated leaching following a saline irrigation experiment of 2.5 years duration. Initial soil electrical conductivity was as high as ECe = 25 mmho/cm with associated exchangeable sodium percentages (ESP) up to 60%. Substantial quantities of solid gypsum and lime were present in the soil profile from precipitation reactions during the crop irrigation stage.

Drainage volumes were expressed in pore volume units to scale out differences between water retention and leaching rates. Plots of scaled chloride concentrations (Cl/Cl initial) vs. pore volumes were similar for all lysimeters, with essentially all chloride removed by 1.5 pore volumes. Total salt removal was well described by a single curve (C/Cinft)(PV) = 0.8 for all treatments. Standard cation exchange equilibrium equations were used in a chromatographic displacement model to produce an algebraic equation to describe exchangeable Na reductions as a function of leaching pore volumes. This model, along with a model for calculating exchangeable Mg reductions, was in good agreement with measured changes for all treatments.

No special amendments were required to maintain high permeability during leaching, even when distilled water was used, because of redissolution of previously precipitated Ca salts.
Effect of Montmorillonite and Trace Elements on the Growth of Penicillium frequentans: II. Nitrate Nitrogen Source
Authors: McCormick R. W. , Wolf D. C.
Published: July 2010

The addition of montmorillonite to culture media has been shown to stimulate growth and metabolic activity of several soil fungi. The objective of this study was to determine if the growth stimulation of a common soil fungus, Penicillium frequentans, was due to montmorillonite supplying required trace elements when glucose and NaNO3 were used as the C‐energy and N sources, respectively.

The trace element treatments were (i) no trace elements, (ii) trace element solution 1, and (iii) trace element solution 2 which contained a 0.1M phosphate buffer plus trace elements. Either montmorillonite, at a concentration of approximately 500 mg/100 ml, or distilled water (controls) was added in dialysis tubing to the trace element solutions.

Without trace elements, the addition of clay increased biomass from 571 to 861 mg/100 ml, an increase of 51%. Biomass production in the controls of both trace element solutions was not significantly different than that produced in the no trace element solution with montmorillonite added. With the addition of clay to trace element solution 1, a 14% increase in biomass from 829 to 944 mg/100 ml was obtained. There was no significant increase in biomass in trace element solution 2, with the addition of clay. The montmorillonite maintained the pH of the medium at least 1.5 units greater than the controls in the no trace element and trace element 1 treatments. With trace element solution 2, a 0.5 pH unit increase after 6 days of growth resulted due to the montmorillonite. When clay was present in the medium, the Cu, Fe, and Mn content of the fungus was increased. As a result of fungal growth, the Zn and Cu contents of the montmorillonite were decreased from 51 to 28 and 37 to 28 µg/g, respectively.

A large portion of the stimulation in fungal growth due to montmorillonite was apparently due to the ability of the fungus to obtain trace elements from the clay. There was however, an increase in growth in trace element solution 1 which could not be attributed to trace elements when NO3‐N was used as a N source.
Dissolution of Sulfur‐Coated Urea in Soil: I. Wax‐Sealed Sulfur‐Coated Urea
Authors: Hashimoto Isao , Mullins R. C.
Published: July 2010

The release of urea from three wax‐sealed, sulfur‐coated urea (SCU) samples was tested in a laboratory soil system. These samples were of nearly matched 7‐day dissolution values but had different amounts of total coatings. Soil‐SCU mixtures were incubated for varying times up to 18 weeks at different temperatures, pH (liming), and microbial (sucrose) levels. The release of urea from all samples increased markedly with increasing temperature but only slightly with increasing pH or microbial levels. Their time‐release patterns were different in spite of their similar 7‐day dissolution test values.
Manganese Toxicity in Flax Growing on Certain Calcareous Soils Low in Available Iron
Authors: Moraghan J. T.
Published: July 2010

Manganese toxicity and high levels of plant Mn are normally found in plants growing on acid soils with high levels of watersoluble or salt‐extractable Mn. However flax (Linum usitatissimum L.) accumulates excessive Mn and develops Mn‐toxicity symptoms, which are eliminated by application of FeEDDHA, when grown on some calcareous soils. Flax was grown in the greenhouse on seven soils, varying in pH and extractable Mn and Fe, in the presence and absence of 2 ppm FeEDDHA‐Fe. Plants on three of the soils, which were calcareous and had the highest pH values, developed Mn‐toxicity symptoms and accumulated approximately 500 ppm Mn in above‐soil parts in the absence of the chelate and less than 50 ppm Mn when the chelate was applied. Plant‐Mn concentration was poorly related to Mn extracted from soils with DTPA (0.005M diethylenetriamine pentaacetic acid, 0.005M CaCl2, 0.01M triethanolamine, pH=7.3), 0.01M CaCl2, 1N NH4OAc (pH=7), or 1N NH4OAc + 0.2% hydroquinone (pH=7), but was significantly inversely related to DTPA‐extractable Fe. It is hypothesized that plant‐Fe status influenced the ability of flax roots to utilize soil Mn, possibly through changes in pH or redox potential at or adjacent to roots.

The influence of P fertilizer, Ca(H2PO4)2, on Mn toxicity in one of the three problem soils, with 3.5 ppm NaHCO3‐extractable P, was also studied. Addition of P greatly increased yields, due presumably to a P response, but also increased plant‐Mn concentration. Manganese‐toxicity symptoms were observed both in the presence and absence of the added P.
Greenhouse Evaluation of Nitrogen Fertilizers for Rice
Authors: Craswell E. T. , Vlek P. L. G.
Published: July 2010

As part of a research program to improve the efficiency of N fertilizers for lowland rice (Oryza sativa, L. var. IR38) in developing countries, a number of modified urea products have been evaluated in a greenhouse experiment. Fertilizers were applied to rice grown in two soils subjected to continuous or intermittent flooding. The results demonstrate the advantages of split application, deep placement, and controlled release in increasing fertilizer efficiency. However, the major finding was that a combination of deep placement and controlled release results in a substantial increase in fertilizer N recovery by the plant. This combination, in the form of sulfur‐coated supergranules of urea, gave a mean apparent recovery of fertilizer N by rice of approximately 84% compared with only 28% for urea applied in a single dose at transplanting.

By using 15N‐labelling, losses of applied N were measured for selected treatments. Extensive losses (∼30% for Decatur soil, ∼50% for Crowley soil) were measured for urea applied at transplanting. Much less (∼6% and 14–24%, respectively) was lost of ammonium sulfate applied similarly. Point application of the urea as a supergranule at the 8‐cm depth reduced losses to < 4%. The intermittent flooding did not promote losses. Losses of broadcast fertilizers were greater from the Crowley soil (pH 6.2) than from the Decatur soil (pH 5.0).
Productivity of Quaking Aspen (Populus tremuloides Michx.) as Related to Soil Mapping Units in Northern Minnesota
Authors: Esu Ivara E. , Grigal D. F.
Published: July 2010

Relationships of quaking aspen (Populus tremuloides Michx.) site index and stand basal area to conventional soil mapping units and soil mapping units regrouped into great group units in northern Minnesota were examined. Soil survey data from three counties mapped at different scales were used; Carlton County at 1:20,000, Itasca County at 1:24,000, and Crow Wing County at 1:31,680. The vegetation data were collected from 0.4 ha, 10‐point cluster forest survey plots. Plots marked on aerial photographs were matched with soil mapping units. Site index for quaking aspen, and for a number of other species, was poorly related to soil mapping units. Stand basal area, however, was related both to mapping units within counties and to the overall great group units. The relationship between forest productivity and soil mapping units needs further evaluation; decisions are necessary regarding the indices appropriate for measurement, and whether the measurement should be of actual or potential productivity.
The Effect of Trickler Line Spacing on Yield of Tomatoes (Lycopersicum esculentum Mill.)
Authors: Tsipori Y. , Shimshi D.
Published: July 2010

Tomatoes (Lycopersicum esculentum Mill. cv. VF 198) growing in rows spaced 80 cm apart, were irrigated with trickler lines spaced every 1, 2, 3, 4, and 5 plant rows. The seasonal amount of irrigation, on a par hectare basis was 600 mm for all the five treatments, so that with wider line spacing, more water was discharged through each line. The lowest yield (70 tons ha−1) was produced by the one‐row spacing, and the highest yield (118 tons ha−1) — by the four‐row spacing. The yield of the rows adjacent to the trickler line increased with line discharge to an extent that overcompensated for the lower yield of the outlying rows. The amount of irrigation applied was lower than potential evapotranspiration, and it is concluded that under these conditions, the higher uniformity of application associated with closer line spacing is a worse irrigation strategy than applying the same amount of irrigation to a portion of the area, thereby enhancing its production at the expense of the drier portion; the probable reason for the low yields under close spacing is the relatively high loss of soil water through surface evaporation, and the shallow soil volume through which transpirational flux occurs.
A Mathematical Treatment of the Initial Stages of Drying of a Soil Column
Authors: Zachmann David W. , Gardner H. R. , DuChateau Paul C.
Published: July 2010

A nonlinear diffusion equation governing the initial stages of drying of a soil column is numerically integrated using a method designed to adjust the time step to compensate for steep moisture content gradients. A balance of mass check is used to determine when the simulation becomes invalid. Resulting tables of relative moisture depletion are given for various soils and drying rates. In view of the improved technique of numerical integration and the attention to the balance of mass check, it is felt that the numerical results obtained are more reliable than previously available results.
Fixation and Loss of Nitrogen During Transformations of Nitrite in Soils
Authors: Smith C. J. , Chalk P. M.
Published: July 2010

When alkaline‐hydrolyzing N fertilizers are band‐applied to soils, the biological oxidation of NO2‐ is inhibited and NO2‐ may accumulate. Nitrite can react chemically with soil organic matter and become fixed, and at the same time nitrogenous gases can be evolved. The aim of the work described here was to study mechanisms of gaseous‐N formation using 15NO2‐ as a tracer, and to define the relationship between fixation and loss of N.

Fixation of Na15NO2 in five soils varying in pH and organic C content ranged from 0.6 to 36% of applied NO2‐, while the 15N not recovered varied from 6 to 53%. A significant positive correlation was found between 15N fixed and 15N not recovered in the five soils, sampled after 1, 2, and 3 days of incubation.

The 15N enrichment of NO + NO2 evolved from three γ‐irradiated soils treated with Na15NO2 was only slightly less than the atom % 15N of added NO2‐, and the rate of evolution increased as the pH of the soils decreased. These data suggest that NO + NO2 was derived from the self‐decomposition of HNO2. Approximately equal amounts of indigenous soil N and added NO2‐‐N reacted to form N2, indicating that a Van Slyke‐type reaction may have been partly responsible. Differences in the atom % 15N2 between soils suggested that more than one loss mechanism was operating, and that their relative importance may have been determined by soil pH. Nitrogen‐15 balance data showed that another nitrogenous gas, in addition to N2O, was evolved.
Soils of Marshes in the Apalachicola, Florida Estuary
Authors: Coultas C. L.
Published: July 2010

The marshes of the Apalachicola, Florida estuary were traversed and the principal soils were described, sampled, and characterized. Cladium jamaicense (sawgrass) was the predominant plant of this ecosystem, but Juncus roemerianus (needlerush) was also common. Sulfihemists predominated in the delta of the Apalachicola River. In the eastern portion of the estuary, Sulfaquents and Fluvaquents were common. Sulfihemists were not saline, but some Sulfaquents and Fluvaquents were saline‐alkaline. Montmorillonite was the predominant clay‐sized mineral and mica was common in the sand fraction.
The Effect of Profile Modification of a Fragiudalf on Water Extraction and Growth by Grain Sorghum
Authors: Bradford J. M. , Blanchar R. W.
Published: July 2010

The dense and slowly permeable layer in fragipan soils restricts the downward movement of water and plant roots. Thoroughly mixing a Hobson soil profile (Typic Fragiudalfs) and incorporating lime and sawdust into the profile increased sorghum grain yields and water storage. Over a 3‐year period, sorghum grain yields were increased by 50% due to the mixing process alone and by 150% when lime and sawdust were added prior to mixing. The water storage in the early growing season was greater in sawdust‐incorporated modified soil plots, and greater amounts of water were utilized by the plants during the growing season. The natural fragipan profile contained the greatest amount of water in late summer, but the water in or below the fragipan was not accessible to the plant because of restriction on rooting.
Cation Exchange Capacity of Acid Forest Humus Layers
Authors: Kalisz P. J. , Stone E. L.
Published: July 2010

Cation exchange capacities (CEC's) of acid forest humus layers and mineral soils were measured at the pH of air‐dried samples (CEC [field pH]) using a neutral salt procedure. The values obtained were ¼ to ½ those measured by NH4OAc at pH 7 (CEC [pH 7]). Organic matter was the chief source of exchange capacity at all localities studied. CEC (field pH) of mors from the Adirondack Mt. area (pH ≤4.1) and mulls from central New York (pH 4.9–5.4) averaged 52 and 123 meq/100 g OM (organic matter), respectively, as compared with 183 and 236 meq/100 g when determined at pH 7. Base saturation calculated from the lower CEC measured at field pH may range from 15 to 30% for H layers below pH 4, and from 81 to 94% for mull layers at pH 5.4. At one location where the pH of a mor layer varied naturally from 3.2 to 5.6, CEC (field pH) was linearly correlated with pH; CEC increased about 30 meq/100 g OM per pH unit. CEC (field pH) was unrelated to total N over the range 1.6–2.6% N, ash‐free. Estimates of total forest floor CEC (field pH) for seven Adirondack and New England localities with mor layers ranged from 10 to 165 keq/ha.
Evaluation of Sulfur‐coated Urea Fertilizers on Merion Kentucky Bluegrass
Authors: Waddington D. V. , Turner T. R.
Published: July 2010

Sulfur‐coated urea (SCU) appears to be both agronomically and economically feasible for use as a slow‐release N source on turfgrasses. Because considerable variation can occur among SCU products, this study was conducted to evaluate six formulations that were representative of different coating weights and coating methods.

Five experimental formulations from the Tennessee Valley Authority and Gold‐N, a product of Imperial Chemical Industries, were applied to ‘Merion’ Kentucky bluegrass (Poa pratensis L.) at a rate of 195 kg N/ha in the spring of 1974, 1975, and 1976. Coating weights of S on TVA materials had been varied to obtain laboratory 7‐day dissolution rates of 17, 26, and 35% from material coated with S only; and 16 and 26% from material coated with S plus a wax sealant. Gold‐N was coated with S plus a paraffin sealant and had a dissolution rate of 36%.

Clipping weights and turf color were used to evaluate turfgrass response. With S‐only coatings, turfgrass response increased as coating weight decreased (dissolution rate increased). Differences due to coating weight were greatest in the first year, and diminished in the following years. In yield and color comparisons over three seasons, a low dissolution rate treatment never produced more response than a higher dissolution rate treatment. In comparison of materials with similar dissolution rates but with different coating methods, release of N was more rapid with a S plus wax coating than with a S‐only coating. The 7‐day dissolution rate was not dependable in predicting field response when coating method was varied.

Plots were sampled for residual CSU in 1976, 1977, and 1978. After three growing season, residual SCU pellets ranged from 3 to 37% of the total applied weight; and after 2 additional years in which no fertilizer was applied, 0 to 13% remained. Variations in SCU formulation caused significant differences in turfgrass response to fertilization and in the amount of residual material; thus, factors such as coating weight and method should be known and taken into consideration when developing a fertilization program based on SCU.
Release of Urea by Granules of Sulfur‐Coated Urea
Authors: Jarrell W. M. , Boersma L.
Published: July 2010

Urea diffuses through holes in the coatings of granules of sulfur‐coated urea (SCU) into the surrounding soil. The ability to predict the rate at which urea is released from SCU granules aids in matching the slow release characteristics of the fertilizer to specific climatic and soil conditions.

When openings are small and the concentration of urea immediately outside each opening is very low, a two‐stage release pattern is proposed. During the initial stage, solid urea is dissolving and urea diffuses out of the granule at a constant rate. When all of the urea inside the granule has dissolved, the rate of release decreases logarithmically with time. The equations describing rates of release during the two stages are
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0001 for the constant rate period, and
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0002 for the falling rate period, where mr = m/Mo with m being the amount of urea released and Mo the amount of urea initially present in the granule, D is the diffusion coefficient, Ap is the cross sectional area of the pore through which diffusion occurs, Δxp is the length of the pore, ρ is the density of urea, and csat is the solubility of urea. The diffusion coefficient D and the solubility of urea csat are temperature‐dependent, according to
urn:x-wiley:03615995:saj2sssaj198003615995004400020042x:equation:saj2sssaj198003615995004400020042x-math-0003 where T is absolute temperature and Tc is temperature in degrees centigrade.

The temperature dependence of the release rate during the constant‐rate period as determined by experiment agreed well with that predicted from theory. These equations may be used to predict the rate of release provided the physical properties of the given SCU are known.
Particle Size Effects on Stockpiling and Spreading Agricultural Limestone
Authors: Alley M. M. , McCart G. D. , Wolf D. D. , Smith E. S.
Published: July 2010

Stockpiling of agricultural limestone is a necessity in many agricultural regions due to transportation and production limitations. Particle size influence on stockpiling and spreading ground limestone must be quantified in order to produce a material that is effective in neutralizing soil acidity and can be uniformly spread after weather‐exposed storage. Effects of particle size on bulk density, percent moisture, and spread pattern uniformity by a commercial twin‐spinner bulk spreader were measured. Calcitic and dolomitic limestones with >60% passing a 100‐mesh (150 µm) sieve bridged in the spreader body and resulted in uneven flow to the spreader spinners. Handling problems were not encountered with materials having <55% passing a 100‐mesh sieve. Ground limestones with particle size distributions of 85 to 88, 48 to 61, and 39 to 56% passing 20‐ (850 µm), 60‐ (250 µm), and 100‐mesh sieves, respectively, were evenly spread after outdoor storage. Bulk densities ranged from 1.34 to 1.53 g/cm3 while moisture contents varied from 0.7 to 6.0%.
Extractability of Phosphorus from Phosphate Minerals Common in Soils and Sediments
Authors: Williams J. D. H. , Mayer T. , Nriagu J. O.
Published: July 2010

A four‐step fractionation scheme has been applied to a large suite of phosphate minerals common in soils and sediments. In general, most of the P contained in iron and aluminum minerals can be extracted by dithionite‐citrate‐bicarbonate (DCB) and/or NaOH treatment. Most of the P bound to apatites was liberated during digestion with 1.0N HCl solution. Thus the scheme provides a reasonable separation of Fe‐ and Al‐bound P from the P generally associated with apatites in soils. A large fraction of the P in fish bones was released by DCB reflecting the influence of the degree of crystallinity on the dissolution of the mineral phases. Crandallite (and related plumbogummite minerals), monazite, and xenotime were not extensively dissolved by the reagents employed in the fractionation procedure.