bluuebunny/crossref_metadata_2025 huggingface dataset:
KINETIC FORMULATION OF THE DENITRIFICATION PROCESS IN SOIL
Authors: CHO C. M. , MILLS J. G.
Published: March 2010

Kinetic formulation of denitrification process in soil was developed based on a model of competitive Michaelis-Menten type enzyme kinetics. Several values of parameters were chosen to plot the concentrations of NO−3, NO−2, N2O-N and N2-N at various times of incubation under different initial concentrations of NO−3. According to the model the disappearance rate of NO−3 was found to be independent of initial concentration of NO−3 and was nearly constant, similar to zero order rate of disappearance. The initial rate of NO−2 formation was independent of the NO−3 concentration. However, the maximum concentration of NO−2 and the time at which the maximum was found were found to be dependent upon the NO−3 concentration. When there was very little accumulation of NO−2 in the system, the initial rate of N2O formation was found to be independent of NO−3 concentration. However, if there was high accumulation of NO−2, the initial rate of N2O formation became inversely related to NO−3 concentration. The initiation of N2 formation was generally slower as the concentration of NO−3 increased. The composition of gas mixture, N2O and N2, was found to vary depending upon the initial NO−3 concentration and with the time of incubation. The formulation presented herein describes the features of denitrification experimentally observed fairly well.
CHEMICAL AND CLAY MINERALOGICAL PROPERTIES OF ORTSTEIN SOILS FROM THE MARITIME PROVINCES
Authors: MILES N. M. , WANG C. , McKEAGUE J. A.
Published: March 2010

The two poorly drained ortstein horizons contained very low amounts (< 0.2%) of Na-pyrophosphate-extractable Fe. The considerably higher values of extractable Al and the fact that clods of ortstein horizons slaked in Na-pyrophosphate suggested that Al-organic complexes might be the major cementing agent, especially in the upper B horizons of the poorly drained pedons. Iron probably contributed significantly to the cementation of other ortstein samples. In the ortstein soils of the Nova Scotia site, minerals in the sola of well drained soils differed markedly from those in poorly drained soils. Vermiculite, apparently derived from mica or chlorite, was the dominant phyllosilicate in the clay fraction of well drained sola but it was not detected in the poorly drained sola. However, in the New Brunswick site, there is little difference in the clay minerals in well and poorly drained soils. Smectite was the dominant silicate clay in Ae horizons; vermiculite was dominant in the B horizons; and mica and chlorite were dominant in the C horizons. Many of the clay samples, especially in the B horizons of the well drained soils, appeared to be amorphous to X-ray. However, treatment with dilute hot NaOH usually greatly enhanced the X-ray diffraction patterns. Scanning electron microscope pictures and the 020 peaks of phyllosilicates in X-ray diffractions patterns indicate that the apparent increase in crystallinity is due mainly to better alignment of the clay particles.
EFFECT OF SOIL WATER STATUS AND STRENGTH ON TRAFFICABILITY
Authors: PAUL C. L. , VRIES J. DE
Published: March 2010

Trafficability tests with typical farm vehicles were carried out on three lowland fields at various degrees of wetness. Structural damage after the first and third passes was assessed in terms of bulk density, aeration porosity, pore-size distribution and rut depth. These indices could not be used per se as criteria for trafficable conditions because of lack of information concerning their relationship to plant growth. Instead, a trafficability criterion oriented toward traction efficiency was established by determining for each soil the relationship between its strength (assessed with a cone penetrometer) and traction efficiency measured by wheelslip. A critical value of strength for trafficability was inferred from this relationship. This was then used to obtain soil water tension limits for trafficability from known relations between tension and strength. Soil strength was found to be linearly dependent upon water table depth in spring when evapotranspiration was small and when the water table depth was less than 80 cm. Consideration of these relationships led to the establishment of critical water table limits for trafficability. These were 53, 45, and 60 cm for Lumbum muck, Hallart silty clay loam (SiCL) (grassland), and Hallart silty clay loam (cultivated), respectively.
SOIL CAPABILITY ANALYSIS FOR REGIONAL LAND USE PLANNING — A STUDY OF THE OTTAWA URBAN FRINGE
Authors: DUMANSKI J. , HUFFMAN E. C. , MARSHALL I. B.
Published: March 2010

A procedure is outlined for analyzing soil data for regional land use planning. Maps of basic land factor limitations are illustrated for the Ottawa urban fringe, and each map is evaluated for biological and nonbiological uses. The major land factors relative to urbanization are used along with other data to derive an urban "suitability" map. Results are compared to the regional development plan for the area.
EFFECT OF CARBON ADDITIONS ON SOIL LABILE INORGANIC, ORGANIC AND MICROBIALLY HELD PHOSPHATE
Authors: CHAUHAN B. S. , STEWART J. W. B. , PAUL E. A.
Published: March 2010

Investigations of the rate of P movement between soil inorganic, organic and biomass P compartments were carried out to clarify aspects of P cycling in soil systems. Organic carbon, as dried grass (33% C, 0.11% P) and cellulose (43% C), was added at a rate equivalent to 4000 kg organic material (OM)∙ha−1 every 30 days for 9 mo to the Ap horizon of a Chernozemic Black soil kept at field capacity moisture content and 24 ± 2 °C. In a third treatment, cellulose was added at the same rate with P (20 kg∙ha−1) at KH2PO4. Approximately 39% and 22% of the P added in grass and with cellulose, respectively, was found in organic P forms after 9 mo incubation. The remainder was found in NH4Cl-, NH4F- and NaOH-NaCl-extractable P forms which constituted part of the labile inorganic P pool and could be extracted by an anion exchange resin. Increases of biomass P during the first 4 or 5 days of each incubation period after residue addition were found to average 12 μg P∙g−1 in the first 3 mo incubation period. After this period, there was a smaller response in microbial P attributable to additions of grass or cellulose.
DIRECT MEASUREMENT OF NITROUS OXIDE FLUX FROM SOIL
Authors: FINDLAY W. I. , McKENNEY D. J.
Published: March 2010

A simple technique for direct measurement of nitrous oxide flux from soils is described. These fluxes were measured at several locations in Essex County in southwestern Ontario and were found to be low from bluegrass and clover sod (3.17 – 4.01 × 109 molecules cm−2 s−1), intermediate from continuous corn and non-agricultural marsh land (16.8 – 32.2 × 109 molecules cm−2 s−1), and high from corn in rotation following alfalfa sod (133 × 109 molecules cm−2 s−1). Considerable variability in rate was observed from day to day and from site to site irrespective of soil type or crop management system. Comparisons are made with measurements obtained in various geographical areas by others.
A RAPID METHOD OF DETERMINING THE DEPTH IN SANDY SOILS AT WHICH MECHANICAL IMPEDANCE WILL PREVENT GROWTH OF APPLE TREE ROOTS
Authors: WEBSTER D. H. , PROUSE C. C.
Published: March 2010

The sound produced when soil is tapped with the handle of a pointing trowel depends upon the degree of compaction. Provided a suitable trowel is used, a distinct ringing sound is produced by the trowel blade if soil is compact enough to prevent growth of apple roots. The method is relatively unaffected by soil moisture within the range of 4 to 30 centibars in soil that contains more than 60% sand.
METHOD OF REPEATED ADDITIONS FOR GENERATING PESTICIDE ADSORPTION-DESORPTION ISOTHERM DATA
Authors: BOWMAN B. T.
Published: March 2010

An improved method is suggested for obtaining desorption isotherm data, which avoids problems associated with decanting supernatant solutions. This technique is also useful in obtaining adsorption isotherm data at equilibrium concentrations approaching the solubility limit of the absorbate.
STRONTIUM-CALCIUM RELATIONSHIP IN CANADIAN SOILS
Authors: McKEAGUE J. A. , WOLYNETZ M. S.
Published: March 2010

The correlation coefficient between total Ca and total Sr levels in 162 soil samples widely distributed in Canada was 0.43. Removal of data for 23 calcareous samples resulted in a markedly higher correlation coefficient (0.87, P < 0.01). The corresponding regression equation Sr (ppm) = 75 + 131 Ca(%) is useful for estimating the Sr level of non-calcareous soil samples.
THE EFFECT OF CONTINUAL USE OF PHOSPHATE FERTILIZER AND BARNYARD MANURE ON YIELD OF WHEAT AND THE FERTILITY STATUS OF A CLAY CHERNOZEM SOIL
Authors: SPRATT E. D. , McIVER R. N.
Published: March 2010

Long-term agronomy experiments with wheat have been maintained at Indian Head, Saskatchewan for more than 30 yr. Yield increases due to barnyard manure (BYM) inputs have become progressively larger over the years whereas the long-term effect of monoammonium phosphate (MAP) on yield of wheat has been cyclic.
MICROMORPHOLOGY AND ENERGY DISPERSIVE ANALYSIS OF ORTSTEIN HORIZONS OF PODZOLIC SOILS FROM NEW BRUNSWICK AND NOVA SCOTIA, CANADA
Authors: McKEAGUE J. A. , WANG C.
Published: March 2010

Cutans that coat and link sand grains in cemented podzolic B horizons (ortstein) of well and poorly drained podzolic soils from Nova Scotia and New Brunswick were described in thin sections and analyzed by energy dispersive spectrometry (EDS). The principal type of cutan was brown and weakly to moderately anisotropic; it included numerous silt and fine sand grains. X-ray spectra showed this type to be composed dominantly of Al and Si with lesser amounts of K and Fe, and minor amounts of P, S, and other elements. The silt and clay particles of these cutans were apparently impregnated with Al, Fe-organic complexes. Another common type of cutan was dark reddish brown, monomorphic and isotropic; it consisted mainly of Al and organic matter as indicated by dominant Al and weak P and S peaks. In a few samples such cutans were composed mainly of Fe and organic matter. Rarer black cutans contained Mn in various proportions. The dominant cementing material of these ortstein horizons was shown to be organic complexes of Al and, less commonly, of Fe. The genesis of soils with ortstein is discussed.
CHARACTERISTICS AND CLASSIFICATION OF NON-CEMENTED SANDY SOILS IN NEW BRUNSWICK
Authors: WANG C. , REES H. W.
Published: March 2010

Forty-nine sandy soils developed in till, outwash, alluvium and marine sands were studied to determine the effect of mode of deposition on soil development and to classify the soils according to the Canadian and U.S. classification systems. Forty-three of the soils met the morphological and chemical criteria of Humo-Ferric Podzols but none of these was a Spodosol because the ratio of pyrophosphate-extractable Fe + Al to clay in the B horizon was below 0.2. Mode of deposition had only a minor effect on soil evolution. However, B horizon development was strongest in the till soils, perhaps because of their somewhat finer texture and greater age. A pronounced maximum of clay occurred in the B horizons of the Podzolic soils; commonly, clay in the B exceeded that in the A and C by a factor of 2–5. A higher pyrophosphate Al/Fe ratio was found associated with soils low in total pyrophosphate Al + Fe and vice versa. It was also found that pyrophosphate Al + Fe was positively correlated with total organic C (r = 0.891).
EFFET DU DRAINAGE SOUTERRAIN SUR QUELQUES PROPRIETES DE SOLS ARGILEUX DU QUEBEC
Authors: KIMPE C. R. DE , LAVERDIÈRE M. R.
Published: March 2010

Four series of agricultural soils of Quebec were sampled in the Lowlands on drained and undrained sites in order to investigate the effect of long-term internal drainage on the physical and chemical properties of the profiles. Change in structure was observed in the Ste-Rosalie soils. A massive layer found below 18 cm in the undrained profile was replaced by a more structured layer at greater depth in the drained profiles. Occurrence of mottles down to the Cg horizon reflected the better aeration conditions in the drained sites. Saturated hydraulic conductivity values were sometimes higher and sometimes lower than those measured in the undrained profiles. Below the plow layer, the two profiles drained for more than 50 yr had a cation exchange capacity 12–15% higher than the undrained profiles. Oxalate-extractable iron represented a high percentage of the dithionite-extractable iron and indicated a low rate of formation of crystalline pedogenic oxides. Mn accumulations were found in the more compact layers. The improvement of internal drainage requires a soil management that will enhance soil structure.
CALIBRATION OF A SINGLE GAMMA PROBE FOR MEASURING WET BULK DENSITY IN ORGANIC SOIL
Authors: VIGIER B. , CAMPBELL J. A.
Published: March 2010

The effect of degree of decomposition and depth of sampling on gamma probe wet bulk density measurements was investigated for two organic soils. Sampling depth did not significantly affect the probe calibration. In situ calibration must be done rather than in laboratory.
PROBLEMS ASSOCIATED WITH EXTRACTING Fe AND Al FROM SASKATCHEWAN SOILS BY PYROPHOSPHATE AND LOW SPEED CENTRIFUGATION
Authors: BALLANTYNE A. K. , ANDERSON D. W. , STONEHOUSE H. B.
Published: March 2010

Atomic absorption analyses of pyrophosphate extractions of B horizons from some Luvisolic, Gleysolic and Solods had higher Fe and Al contents when using 0.1% Superfloc and low speed centrifugation than those obtained when using 0.2% or 0.5% Superfloc or when using high speed centrifugation. Laboratories not equipped with a high speed centrifuge should use a method other than Superfloc to clarify the solution or use the recommended colorimetric method.
INFLUENCE OF pH AND METAL ION CONTENT ON VANADYL ION-FULVIC ACID INTERACTIONS
Authors: McBRIDE M. B.
Published: March 2010

Electron spin resonance (ESR) has been used to investigate the chemical nature of the VO2+-fulvic acid complex. The chemical nature of this complex was not affected by the quantity of VO2+ bonded to a given amount of organic. Very low pH values prevented VO2+ from bonding with fulvic acid, but insignificant quantities of free VO2+ remained in solution at pH values of 4 or higher. The bonding environment of the metal in fulvic acid was not very different from that in humic acid extracted from the same soil. Aluminum competed with VO2+ for complexing sites in the organic, causing the number of organic ligands attached to VO2+ to be less than that for demetallated soil organics. Very high pH caused all of the VO2+ associated with fulvic acid to be oxidized except for a very small quantity that was apparently strongly complexed to four nitrogen ligands of a relatively low molecular weight organic, possibly porphyrin.
FORMATION D’HORIZONS CIMENTES DANS LES SOLS SABLEUX DU DELTA DES RIVIERES MANICOUAGAN ET OUTARDES, QUEBEC
Authors: PAGÉ F. , ROMPRÉ M. , KIMPE C. R. DE , BOURBEAU G. A.
Published: March 2010

Three profiles, one Fibrisol and two Podzols, developed on the deltaic sediments of the Manicouagan and Outardes rivers, have been analyzed. The mineral deposits contain two different layers. The upper one, rich in silt and clay, corresponds to the latest stage of sedimentation in shallow waters, while the lower layer is sandy in texture. The impervious nature of the upper layer due to a massive structure and a large content of fine particles has favored the formation of very extensive peatlands. At the edge of the former beachline, drainage is improved and Podzolic soils have developed. The fine-textured layer found under the organic deposits of the Fibrisol is partially disrupted by the roots in the Podzolic soil. In the third profile, this layer is more completely disorganized but the A and B horizons still contain relic fragments, which are cemented by podzolic material. At depth, this profile also contains cemented horizons. Cement is composed of podzolic material and illuviated clay. Micromorphological analysis contributed to an explanation of the evolution of the spodic organizations in the soils and to an understanding of the origin and formation of the cemented horizons.
TEMPERATURE, MOISTURE AND COMPACTION AND THEIR EFFECTS ON THE DIFFUSION OF ETHYLENE DIBROMIDE IN THREE ONTARIO SOILS
Authors: TOWNSHEND J. L. , DIRKS V. A. , MARKS C. F.
Published: March 2010

Three southwestern Ontario soils differing in texture were studied for penetration of the nematicide ethylene dibromide. A 3 × 2 × 2 factorial experiment was used that permitted evaluation of the effects of temperature, bulk density and moisture level in all combinations on response to the fumigant. The coursest soil (Fox loamy sand) showed the most rapid penetration, with moisture level, temperature and their interactions having the greatest effect on fumigant movement. On a medium-textured soil (Vineland silt loam) the degree of penetration was dependent on moisture, temperature and bulk density, with relatively small interaction effects, suggesting that effective fumigation depends upon careful soil management and timeliness of application. On the fine-textured soil (Lincoln clay) the fumigant did not move in the soil, regardless of edaphic factors, thereby explaining the difficulty of using fumigation to control nematodes on clay. The development of factorial methods and statistical techniques to study several variables concurrently should lead to more specific and effective methods of soil fumigation.
SOME CHEMICAL AND PHYSICAL PROPERTIES OF SERPENTINE SOILS FROM WESTERN NEWFOUNDLAND
Authors: ROBERTS B. A.
Published: March 2010

Two serpentine soils from western Newfoundland have been described and their chemical and physical properties documented. The Blomidon soil series is a moderately well to imperfectly drained Gleyed Regosol, cryoturbic phase, and the Round Hill series a well to moderately well drained Orthic Regosol, cryoturbic phase. Both soils developed from base-rich very stony, sandy-loam colluvium and till, derived mainly from serpentinized rocks. Horizon development is restricted by cryoturbation and this factor, combined with high Mg content (12–16%, total) (6.8–16.64 meq/100 g, available) and low essential macronutrient content, create adverse conditions for plant growth. In addition, there are present possibly toxic quantities of Ni (0.308–0.389% total) (0.008–0.031 meq/100 g available). The Ca/Mg ratios are 0.008–0.190, total and 0.030–0.361, available; soil textures are loam to sandy loam. Comparison is made to serpentine soils in Poland, Sweden, Great Britain, Rhodesia and the U.S.A., similarities and differences being noted.
EFFET DU MAGNÉSIUM ET DU pH DU SOL SUR LA LUZERNE CULTIVÉE EN SERRE DANS TROIS TYPES DE SOL DU QUÉBEC
Authors: DIONNE J. L.
Published: March 2010

Aflalfa (Medicago sativa L. ’Saranac’) was grown under greenhouse conditions in order to determine changes in magnesium (Mg) response and availability following variation in soil pH. The rates of Mg applications were 0, 25, 50, 100 and 200 ppm of Mg calculated on soil dry weight basis. Soil pH was adjusted to 5.0 (or original) 6.0, 6.5 and 7.5. A 40% yield increase was recorded on Greensboro loam following Mg fertilization. The increase in yields due to Mg was 23% on the two others soil types. The Mg contents of plant and soil increased with rate of Mg applied to soil. In general, the response of alfalfa was increased by liming soils and the Mg content of alfalfa was decreased. The availability of Mg in soils was also lowered by liming. The Mg requirement of soils varied from 25 to 100 ppm depending upon pH and soil types.
MONOSACCHARIDE COMPOSITION OF PEAT FRACTIONS BASED ON PARTICLE SIZE
Authors: MORITA H. , LEVESQUE M.
Published: March 2010

The yields of monosaccharides from peat fractions in five organic soils segregated by particle size revealed that as a general trend, the total monosaccharide content decreased as particle size decreased. However, in some peats, the 100-mesh fraction yielded more monosaccharides than the 40-mesh fraction. Likewise, the 200-mesh fraction yielded more monosaccharides than the 100-mesh fraction. The < 200-mesh fraction, however, consistently gave lower yields of the monosaccharides than the 100-mesh fraction. Among the individual monosaccharides, glucose was predominant and its abundance together with xylose and galactose were generally associated with particle size. The foregoing results suggest that decreasing particle size of peat materials need not always imply increasing degree of decomposition. The results also show that the monosaccharide content in the < 200-mesh particles may usefully complement the conventional fibre determination as a measure of the degree of decomposition.
ESTIMATION OF MANITOBA SOIL TEMPERATURES FROM ATMOSPHERIC METEOROLOGICAL MEASUREMENTS
Authors: REIMER A. , SHAYKEWICH C. F.
Published: March 2010

Soil-temperature studies were conducted under forage and zero tillage conditions at the Whiteshell Nuclear Research Establishment (WNRE), Pinawa, Manitoba, as part of the plant radiation ecology research program. The objective was to develop estimation equations for monthly mean and daily mean soil surface temperatures from atmospheric meteorological measurements. Subsoil temperatures were estimated from predicted soil surface temperatures by applying an appropriate damping factor. Monthly mean soil surface temperatures were estimated for summer and winter months from regression equations with meteorological predictors. Daily mean soil surface temperatures were predicted from regression equations with meteorological predictors combined with best-fit Fournier-series seasonal curves. Daily mean subsoil temperatures at 10 cm were estimated from predicted soil surface temperatures by applying an appropriate damping factor. The standard deviation of the difference between predicted and observed temperatures was generally less than 1 °C for daily and monthly estimates. A good estimate of the seasonal subsoil temperature at 10, 50, 100 and 200 cm was found from a periodic function with damping and phase paramaters. The explained variance was 95% or more. With appropriate assumptions regarding soil thermal properties and mean annual soil temperature, accurate results were obtained quickly and economically.
SUMMER TEMPERATURES OF CRYOSOLIC SOILS IN THE NORTH-CENTRAL KEEWATIN, N.W.T.
Authors: TARNOCAI CHARLES
Published: March 2010

Soil temperatures were measured at six depths within 1 m of the surface on 10 Cryosolic soils in the north-central Keewatin area during the summer of 1976. The mean soil temperatures during the study period varied between 1.7 °C and 8.2 °C at a depth of 20 cm and −0.2 °C and 6.0 °C at a depth of 50 cm. The maximum and minimum soil temperatures at a depth of 20 cm ranged from 4.4 °C to 13.9 °C and from −0.6°C to 3.9 °C, respectively, while those at a depth of 50 cm ranged from −0.2 °C to 6.7 °C and from −1.1 °C to 2.2 °C, respectively. During the study period a freeze-back of 30 cm or more occurred from the permafrost on several sites. Soil temperatures were markedly higher where the soil material and vegetation were disturbed. The effects of drainage, soil materials, aspect, slope position, vegetation and peat cover on the soil temperature are discussed.
EFFETS DU SOUS-SOLAGE ET DU LABOUR PROFOND SUR LES PROPRIETES PHYSIQUES DU SOL ET LE RENDEMENT DE LA LUZERNE ET DU MAIS SUR LOAM SABLEUX CHALOUPE
Authors: COTE D. , DUPUIS G.
Published: March 2010

Following deep plowing and subsoiling treatment in 1971, alfalfa and corn silage were grown continuously during a 5-yr period on Chaloupe soils which have an indurated layer at 40 cm or deeper. These soils were formed from laminated particles of very fine sand and loam of recent sedimentary origin. Measurements taken in 1972 and 1975 included bulk density, resistance to penetration, permeability, organic matter content and soil texture. Subsoiling did not significantly change soil physical properties; only a slice of soilless than 10 cm wide at depth 50 cm and deeper on each side of and in the furrow made by the ripper showed modifications, without affecting crop yields. Deep plowing, however, in turning the soil by 120° to 150° resulted in redistribution of the organic matter and the soil texture down the profile, a diminution in resistance to penetration in the subsoil. But it did not change the porosity or the permeability of the lower layers. Physical modifications brought by deep plowing were still persistent after more than a 3-yr period. Improvement in physical and hydrodynamic soil properties following deep plowing did not have any beneficial effect on corn and alfalfa yields.
DENITRIFICATION, NITROGEN FIXATION AND NITRIFICATION IN CONTINUOUS FLOW LABORATORY SOIL COLUMNS
Authors: HYNES R. K. , KNOWLES R.
Published: March 2010

Apparent steady state denitrification and N2 fixation were simultaneously detected in soil columns supplied with a solution containing glucose (250 μg C∙mL−1) and potassium nitrate (10 μg N∙mL−1. The addition of 10.1 kPa (0.1 atm) C2H2 to the air flow through the column resulted in depth profiles of N2O and C2H4 which showed that a zone of active denitrification was underlain by a zone of C2H2 reduction. About 90% of the added NO3− was denitrified and about 10% of the products was N2O. Continuous addition of ammonium chloride (25 μg N∙mL−1) resulted in steady state oxidation of all the NH4+. The introduction of C2H2 (10.1 kPa), however, inhibited nitrification and caused washout and disappearance of NO3− from the column effluent. On removal of C2H2, nitrification activity returned only very slowly. Nitrification of added NO2− was not affected by C2H2. No N2O was detected during steady state oxidation of NH4+ or NO2− in the presence or absence of C2H2, indicating that nitrification-denitrification coupled reactions did not occur under the conditions employed.
CROP YIELDS AND SOIL MANAGEMENT ON THE CANADIAN PRAIRIES, PAST AND PRESENT
Authors: RIDLEY A. O. , HEDLIN R. A.
Published: March 2010

Agricultural land use and cropping statistics were examined to determine yield trends of wheat and barley since the early 1900’s. A general decline in yields of these crops occurred until the return of favorable weather and introduction of disease-resistant varieties in the mid-1930’s. Since about the mid-1950’s, yields of wheat and barley have been greater than at any previous period, and have generally been increasing rapidly during the period 1958–1978. An estimate of the contribution of modern technology to the increased yields was calculated, using 5-yr moving averages for the periods ending 1962 and 1978. Increased fertilizer use had the greatest effect on yield increases achieved. New disease-resistant varieties with improved yielding potential had a lesser effect. The impact of herbicides and improved machinery was examined but could not be effectively evaluated from available data.
EVALUATION DES CRITÈRES DE DIFFÉRENCIATION POUR LA CLASSIFICATION DE 92 MATÉRIAUX TOURBEUX DU QUÉBEC ET DE L’ONTARIO
Authors: LÉVESQUE M. , DINEL H. , MARCOUX R.
Published: March 2010

In order to evaluate the differentiation criteria for classification of organic soils, 92 peat-like materials have been characterized according to criteria generally used by the Canadian Pedological Commission (C.P.C.). The botanical composition and the Ca:Mg ratio have been added to these criteria. A close relationship was found (r = −0.865**) between the pyrophosphate indices obtained by the method adopted by C.P.C. and those measured using the Kaila method. The distribution of peat-like materials which are classified as fibric, mesic and humic was different depending on whether the differentiation criterion used was rubbed fibre or pyrophosphate index. A classification using the first criterion gives a dominant mesic population, while the second criterion favored the fibric group. The curvilinear relationship obtained between the content of rubbed fibres and the pyrophosphate index shows that the degree of decomposition measured by these criteria was proportional only for materials which are fundamentally fibric or humic. The mesic group is more or less well-defined by the two criteria. The botanical composition proved to be the most discriminatory differentiation element. Also, a previous grouping of the materials according to this criterion would ensure a more orderly and efficient utilization of the other characterization criteria, and would provide a better-defined differentiation of the mesic materials.
THE VARIATION OF IN SITU MEASURED SOIL WATER PROPERTIES WITHIN SOIL MAP UNITS
Authors: TOPP G. C. , ZEBCHUK W. D. , DUMANSKI J.
Published: March 2010

The in situ saturated hydraulic conductivities of nine soil units were measured and cores of the same soil were taken to the laboratory for determination of desorption water capacity relationships. Hydraulic conductivities for the coarse- and fine-textured soils were equivalent and higher than that for medium-textured soils. However, the coarse- and fine-textured soils showed measurably different desorption curves for each of three soil units tested. Variability of duplicate measurements of hydraulic conductivity at sites were found to be considerably less than that of the soil unit as a whole. The highly variable in situ hydraulic conductivities resulted in separations of two groups of soil with significantly different values. A third intermediate group was not significantly different from the other two. The desorption curves were discussed in relation to differences in pore size distributions, identifying proportions of the pore space attributable to structural pores and to textural pores.
STORAGE EFFECTS ON NUTRIENT MINERALIZATION IN CONIFEROUS FOREST FLOOR SAMPLES
Authors: ARP P. A. , KING H. B. , KRAUSE H. H.
Published: March 2010

Forest floor samples were obtained from three mature, even-aged, naturally regenerated conifer stands which varied with respect to drainage and indigenous soil fertility. Field moist subsamples were stored for 200 days in a refrigerator maintained at 4 °C and in a freezer maintained at − 10 °C; in addition, forest floor samples, dried at 60 °C for 48 h, were stored at room temperature. Subsamples were extracted initially and at predetermined time intervals with 2 N KCl (to determine mineral NH4+-N and NO3−-N), with neutral 1 N ammonium acetate (to determine water-soluble + exchangeable K, Ca, and Mg), and with distilled water (to determine soluble P). At 4 °C, extractable NH4+-N changed little during the first week of storage but increased steadily thereafter at rates which appeared to increase with increasing total N. Nitrification, present only in the sample taken from the most fertile site, commenced after 40 days of refrigerated storage. Concentrations of soluble P decreased initially, but rose thereafter at low, moderate, and high rates depending on total P. Freezing changed mineral NH4+-N to a minor extent, whereas NO3−-N was not affected. Concentrations of soluble P increased steadily during the first 2 mo of storage at − 10 °C. Levels of extractable K, Ca, and Mg were not affected by refrigeration and by length of storage time, but freezing increased extractable K considerably. Drying at 60 °C for 48 h produced abrupt increases in exchangeable + water-soluble nutrient levels. Further changes, however, were not observed during subsequent storage at room temperature.
COMPARISON OF FOUR METHODS OF MEASURING VOLATILIZATION LOSSES OF NITROGEN FOLLOWING UREA FERTILIZATION OF FOREST SOILS
Authors: MARSHALL VALIN G. , DEBELL DEAN S.
Published: March 2010

Four methods were compared for measuring ammonia volatilization losses following urea application (220 kg N/ha) to a forest soil from Vancouver Island: (i) closed-static, (ii) semi-open, (iii) 15N-balance, and (iv) closed-dynamic. The first three methods were used in the field; the fourth in the laboratory. In addition, the effects of two levels of simulated rainfall were assessed with methods ii, iii and iv. Significantly greater [Formula: see text] amounts of volatile ammonia were measured by each of the following three methods in the order: closed-static (13%) < semi-open (17%) < closed-dynamic (22–26%). The 15N-balance method measured 35–42%, but these values could not be compared directly with the other three methods, because it measures losses from gases other than ammonia alone. The simulated 12-mm rainfall significantly [Formula: see text] decreased ammonia losses, but did not change the relationship among methods: semi-open < closed-dynamic < 15N-balance for 9, 12 and 22%, respectively. Since estimated ammonia losses (i.e. total minus other gases) in open microplots with 15N-urea approximated that obtained by the closed-dynamic method, the latter gives a more representative estimate of ammonia losses than the semi-open or closed-static systems. Losses from nitrogen oxides (NO and NO2), measured by the closed-dynamic method, were less than 1% of the applied fertilizer, while unaccountable losses by the 15N-balance method approached 23%. This suggests that losses as di-nitrogen (N2) and nitrous oxide (N2O), following urea application to forests, might be more important than is usually recognized. Significant differences in ammonia recovery by the closed-dynamic method from non-tracer (standard) granules and 15N-enriched granules (26 vs. 22%) was unexpected. Further research is warranted to determine the effects of re-processing techniques used to enrich the 15N content of urea.
AN INEXPENSIVE INSTRUMENT FOR MEASURING SOIL WATER TABLE LEVELS
Authors: CAMPBELL JAMES A. , MILLETTE JACQUES A. , ROY MARIO
Published: March 2010

A simple and inexpensive instrument for measuring soil water table levels that can be used with metal or plastic wells was designed and constructed. The accuracy of the measurements is within ± 1 mm. The instrument has been thoroughly tested both in the field and in the greenhouse and proved to be very reliable.
AN IMPROVED PROCEDURE FOR MEASURING WATER RETENTION CURVES AT LOW SUCTION BY THE HANGING-WATER-COLUMN METHOD
Authors: BERLINER PEDRO , BARAK PHILLIP , CHEN YONA
Published: March 2010

An improved procedure for measuring water retention curves at low suction (0–300 mbar) by the hanging-water-column method is described. The proposed method produces curves obtained on the same sample over the whole range of measurements. Good agreement was found between data measured by the proposed technique and those obtained by a conventional pressure plate technique.
REGRESSION ANALYSES OF GRAIN YIELD OF CORN, LEVEL OF LEAF N P K AND SOIL CONDITIONS IN A LONG-TIME ROTATION EXPERIMENT ON BROOKSTON CLAY
Authors: DIRKS V. A. , BOLTON E. F.
Published: March 2010

Regression and covariance analysis of a 13-yr rotation experiment of corn on Brookston clay soil showed that grain yield of corn could be related to each of nine other plant and soil measurements. Soil compaction as measured by bulk density was negatively associated with the level of leaf K in the plants, as well as available soil moisture. The major part of the yield difference between fertilized continuous corn and fertilized corn following alfalfa could be accounted for by multiple regression of grain yield on leaf N and K nutrient levels, soil compaction and soil moisture. Soil compaction was not affected or modified by fertilizer treatment. Response of corn grain yield to soil conditions, moisture and plant nutrient level appears to vary with rotation and fertilizer input.
OXYGEN FLUX MEASUREMENTS IN ORGANIC SOIL
Authors: CAMPBELL JAMES A.
Published: March 2010

Many measurements of oxygen flux in mineral soils have been reported; however, few such measurements have been made in organic soil. Almost all reported measurements of oxygen flux are at constant applied voltage, despite criticism of this technique, possibly due to the complexity of existing techniques for measuring oxygen flux at effective voltage. Equipment suitable for measuring oxygen flux at applied and effective voltage in organic soil was designed, and simplified techniques were developed and tested. As reported for mineral soils, soil resistance is relatively constant spatially and with depth in individual soils. Limited poisoning of the platinum electrode surface occurred after long periods of time and, contrary to previous assumptions, cannot be detected by erratic readings. Unlike mineral soil, the amperage-voltage slopes are constant over a wide range of organic soils, simplifying the technique for estimating oxygen flux at constant effective volatage. Comparison of simultaneous measurements of oxygen flux at constant and effective voltage indicates that oxygen flux measurements at effective voltage were twice those at applied voltage and strongly correlated (r2 = 0.96, n = 22).
A TWO-FACTOR SYSTEMATIC DESIGN FOR FERTILIZER STUDIES
Authors: LUTWICK L. E. , KOZUB G. C. , SMITH A. D.
Published: March 2010

N and P fertilizers were applied at increasing rates in alternating directions crossed over (IRADCO) at right angles upon each other. One fertilizer was applied so that, in the contiguous strips, the rates increased in alternate directions. The second fertilizer was applied similarly but at right angles to and on top of the first fertilizer. This arrangement with the increasing-rate spreader available allowed 162 combinations of the two fertilizer elements in duplicate in each block. Two such blocks set at right angles to each other were considered to offer reasonable control of possible fertility gradients in the field. The main value of the design is that many fertilizer levels for the establishment of yield response surface functions can be acquired with less effort and in a fraction of the area required with plots of conventional size. The form of the yield response to fertilizer was adequately represented by regression models fitted to the data. The IRADCO design, involving both the field technique and regression modelling, can be used to determine the response to fertilizer levels by various crops at several locations.
TEMPERATURE DEPENDENCE OF NITROUS OXIDE PRODUCTION FROM BROOKSTON CLAY
Authors: McKENNEY D. J. , SHUTTLEWORTH K. F. , FINDLAY W. I.
Published: March 2010

A gas-stripping flow system is described whereby an inert gas, He, is used to remove nitrogenous product gases from a soil column undergoing anaerobic denitrification under steady state conditions. Net rates of nitrous oxide N2O, production are measured, for Brookston clay over a temperature range of 4–25 °C. The calculated Arrhenius activation energy for net N2O production remained approximately constant at 79.9 kJ∙mol−1 over a 37-day period. The emission rates declined slowly over the period by roughly a factor of 2. The significance of these results is discussed with comparisons to results obtained by others on the effect of temperature on denitrification rates in a variety of soils.
THE INFLUENCE OF SOIL MOISTURE ON UREA HYDROLYSIS AND MICROBIAL RESPIRATION IN JACK PINE HUMUS
Authors: FOSTER N. W. , BEAUCHAMP E. G. , CORKE C. T.
Published: March 2010

The influence of soil moisture on urea hydrolysis and microbial respiration in mixed L and F horizons of a Brunisolic soil under a boreal forest jack pine (Pinus banksiana Lamb.) stand was determined in an incubation study at 13 °C. Respiration rates in untreated soil were similar over a wide range of moisture contents below 300% (45% water-holding capacity). Significant decreases in respiration rates occurred only below 60% moisture content. Initial microbial response to urea increased as soil moisture rose from 20 to 300%. There was sufficient urease in pine humus to hydrolyze rapidly the equivalent of 200 kg urea-N∙ha−1, when moisture was not limiting. During the drying of initially moist soil (340% H2O) to 240% H2O or lower, urea hydrolysis was retarded significantly and microbial respiration reduced by an average of 25% over that observed in a constantly moist soil.
EVALUATION OF METHODS OF EXTRACTING SOIL CATIONS FOR FOREST PRODUCTIVITY STUDIES IN SOUTHWESTERN BRITISH COLUMBIA
Authors: KLINKA K. , FELLER M. C. , KOZAK A. , LAVKULICH L. M.
Published: March 2010

The NH4OAc pH 7 method has been used traditionally to assess the availability of cations in soils for tree growth in coastal British Columbia but there have been no attempts to assess the validity of the method for this purpose. This objective was accomplished by determining the quantities of extractable cations (K, Mg, and Ca) in 42 forest soils in the Coastal Western Hemlock Biogeoclimatic Zone of British Columbia using four different extraction methods. The methods used were the NH4OAc pH 7, NH4OAc pH 4.8, 10% HCl, and 1% citric acid methods. A stepwise elimination multiple-regression technique was used to test the relationship of extracted cations to forest productivity. The amounts of cations extracted by the NH4OAc method were well-correlated with those extracted by each of the other three methods. Of the cation quantities extracted, those of Ca were best, although still poorly correlated with productivity. Of the extraction methods, the NaOAc method yielded quantities most closely correlated with productivity and is recommended for use in assessing the cation status of forest soils in the Coastal Western Hemlock biogeoclimatic zone.
MICROMORPHOLOGICAL INVESTIGATIONS OF CULTIVATED GRAY LUVISOLS UNDER DIFFERENT MANAGEMENT PRACTICES
Authors: PAWLUK S.
Published: March 2010

Research on cultivated and uncultivated Gray Luvisols at the Breton Plots was conducted to determine the effects of management practices on soil fabric arrangements. Soil fabrics were readily classified into two dominant groupings: the granic sequence for cultivated layers and upper solum of uncultivated soil and the fragmic sequence for Bt horizons. Mullgranic and humigranic sequences were also characteristic of pedotubules in all horizons examined. The investigations showed that tillage practices play a much larger role in determining fabric arrangements than do fertilizer treatments, within and among f-members best classified as crumbs and clods. However, clods, crumbs and crusts of cultivated layers were frequently found to comprise basic granic units (approximately 150–200 μm) which expressed a variable degree of granularity. The granules were most discrete and strongly developed in plots receiving organic fertilizer and where grasses and cereals were grown in rotation; their plasma fabric also showed a weak mull component. While the exact genetic origin of the granules is unknown, it appeared that soil fauna were at least in part responsible for their formation.
MORPHOLOGY AND CLASSIFICATION OF SOME DARK-COLORED SOILS OF VANCOUVER ISLAND, BRITISH COLUMBIA
Authors: BROERSMA KLAAS , LAVKULICH L. M.
Published: March 2010

In the southeastern portion of Vancouver Island are found soils that are dark-colored in their surface horizons. These dark-colored surface horizons are mainly the result of the climate and vegetation. The surface horizons can be classified as either Ah(f) or Bhf horizons using the criteria of the System of Soil Classification for Canada. The B horizons were designated podzolic (Bf or Bhf) even though not all criteria were met for all horizons. The soils were classified as Sombric Humo Ferric Podzols, as this subgroup appeared the most suitable.
NATURAL ABUNDANCES AND MINERALOGICAL PARTITIONING OF TRACE ELEMENTS IN SELECTED ALBERTA SOILS
Authors: DUDAS M. J. , PAWLUK S.
Published: March 2010

Background levels of As, Cd, Co, Cu, Pb, and Zn in Chernozemic and Luvisolic soils from Alberta were established and are similar to the average terrestrial abundances in shale and granite. Redistribution of As, Cd, Co, Cu, and Zn within the solum was more pronounced in Luvisolic soils than in Chernozems. Partitioning of the six trace elements, determined by analysis of particle size separates, was unique for each element. Copper and zinc were more uniformly enriched in clay separates than were the other four trace elements. Differences in the content of trace elements within and among soils arise not only from textural variation, but also from large variations in the quantity of trace elements within a specific particle size fraction.
GRAPHICAL PREDICTION OF POROSITY AND WATER RETENTION IN SAND-SOIL MIXTURES FOR DRAINED TURF SITES
Authors: SPOMER L. ART
Published: March 2010

Sand-soil mixtures are commonly used in drained turf sites such as golf greens and athletic fields to ensure adequate soil strength, minimum compaction, and corresponding suitable water retention and infiltrability. The physical properties of the components vary significantly from site to site and mixture proportions must be adjusted to compensate for this. This adjustment usually involves empirical testing of various mixtures of the components to determine the correct proportions to use. One objective of this project is to develop a simple, applied method useful in the prediction of mixture porosity and water retention, which might eliminate or at least significantly reduce empirical testing. A graphical method based on component bulk volume proportions and which requires knowledge of the component porosities was developed and demonstrated to accurately predict water retention porosity, aeration porosity, and total porosity in sand-soil mixtures. This method, described herein, should prove of practical use in determining correct mixtures of sand and soil for drained turf sites.
Fréchet differentiability of Lipschitz functions via a variational principle
Authors: Lindenstrauss Joram , Preiss David , Tišer Jaroslav
Published: March 2010

We prove a new variational principle which in particular does not assume the completeness of the domain. As an application we give a new, more natural, proof of the fact that a real valued Lipschitz function on an Asplund space has points of Fréchet differentiability.
The end curve theorem for normal complex surface singularities
Authors: Neumann Walter D. , Wahl Jonathan
Published: March 2010

We prove the “End Curve Theorem,” which states that a normal surface singularity

(X,o)

with rational homology sphere link

Σ

is a splice quotient singularity if and only if it has an end curve function for each leaf of a good resolution tree.

An “end curve function” is an analytic function

(X,o) → (ℂ, 0)

whose zero set intersects

Σ

in the knot given by a meridian curve of the exceptional curve corresponding to the given leaf.

A “splice quotient singularity”

(X,o)

is described by giving an explicit set of equations describing its universal abelian cover as a complete intersection in

ℂ^t

, where

t

is the number of leaves in the resolution graph for

(X,o)

, together with an explicit description of the covering transformation group.

Among the immediate consequences of the End Curve Theorem are the previously known results:

(X,o)

is a splice quotient if it is weighted homogeneous (Neumann 1981), or rational or minimally elliptic (Okuma 2005).