bluuebunny/crossref_metadata_2025 huggingface dataset:
INTEGRAL LAND EVALUATION AND ITS APPLICATION TO POLICY
Authors: SMIT B. , BRKLACICH M. , DUMANSKI J. , MacDONALD K. B. , MILLER M. H.
Published: March 2010

An approach to integral land evaluation is described and its application to land use policy issues is demonstrated. The approach provides a link between bio-physical land-related information bases and the information requirements of land use planning. It is based upon the premise that the importance of a land unit for a particular use can be determined by assessing the available land units and their productivities relative to the societal requirements for products and services from the land. A mathematical model specifies land use constraints, representing limitations on resource availability and goals for production, and identifies land use options that are feasible under the specified conditions. This modelling approach provides quantitative information on land use flexibility and on the critical importance of certain land areas for specified uses, given both the bio-physical and socio-economic conditions. For demonstration, a prototype model for the agri-food sector is applied to Ontario under three scenarios, showing the sensitivity of different regions and land types for agricultural production. Key words: Integral land evaluation, physical land evaluation, land use policy, resource constraints, production targets, land use flexibility
THE NATURE OF SMECTITES IN SOME FINE TEXTURED LACUSTRINE PARENT MATERIALS IN SOUTHERN SASKATCHEWAN
Authors: MERMUT A. R. , GHEBRE-EGZIABHIER K. , St. ARNAUD R. J.
Published: March 2010

Detailed mineralogy and chemistry of the clay fraction of five glacio-lacustrine deposits and of one Cretaceous marine shale (Ashville) were studied. Fine clay separates (< 0.2 μm) of the five parent materials were predominantly smectite with an average chemical composition:[Formula: see text]X-ray diffraction, dehydration, infrared, and chemical analyses, and the Greene-Kelly test showed that the smectite was an iron rich montmorillonite. Similarities in the crystal structure of the five soil parent material clays suggest that they were likely transported from the same source. Despite the differences in percentage of clay minerals, similarities between chemical composition of the coarse and the fine clays is interpreted as an indication of close diagenetic relationships between the predominant smectite and soil mica. High silicate bound iron may have caused a distortion in the crystal lattice and a slightly favorable weathering condition of smectites. However, presence of high exchangeable and soluble magnesium in the soil complex is likely retarding the smectite alteration. Thus, weathering by elemental substitution may have been restricted to the smectite end member only. Key words: Swelling clay soils, iron montmorillonite, chemical composition of smectites, dehydration of smectites
MISE EN EVIDENCE DE GOETHITE EN SUSPENSION DANS LES EXTRAITS PYROPHOSPHATE ET TETRABORATE DE CERTAINS SOLS GRESEUX DU PORTUGAL
Authors: MADEIRA M. A. VALERIANO , JEANROY E.
Published: March 2010

Five chemical reagents (citrate-bicarbonate-dithionite, oxalate, EDTA, pyrophosphate and tetraborate), generally used for studying iron forms, were applied to sandy soils from Portugal. The results emphasized anomalies in the order of efficiency of these reagents. In deep horizons particularly, a greater extractibility of iron by pyrophosphate, and sometimes by tetraborate, than with oxalate was noted. After separating particles in suspension in pyrophosphate and tetraborate extracts, it was shown that these particles were not entirely soluble in oxalate, and that they consisted of goethite, well-identified by X-ray diffraction and infra-red spectroscopy. It was concluded that iron, present as particles in the peptising reagents, such as pyrophosphate and tetraborate, was not only in the amorphous organic complex state. These results confirm those obtained by Schuppli et al. (1983) for pyrophosphate, but are new for tetraborate. Key words: Chemical extraction (Fe, Al), iron forms, flocculation, ethanol
SOIL ACIDITY IN RELATION TO SOIL PROPERTIES AND LIME REQUIREMENT
Authors: CURTIN D. , ROSTAD H. P. W. , HUANG P. M.
Published: March 2010

The nature and components of acidity in a group of 20 Saskatchewan soils (pH 5.0–5.8) were investigated. KCl-exchangeable acidity was very low (0.3–2.2 mmol(+)∙kg−1) in all soils. Titratable acidity, determined as the difference between effective CEC and buffered (at pH 8.1) CEC, ranged from 9 to 191 mmol(+)∙kg−1 and constituted about 99% of the total acidity in the soils examined. Titratable acidity was highly correlated with organic carbon (r = 0.83) and with Al extracted using citrate-dithionite-bicarbonate (r = 0.95), potassium pyrophosphate (r = 0.92) and pH 4.8 ammonium acetate (r = 0.79). The combination of organic carbon and citrate-dithionite-bicarbonate-extractable Al accounted for 96% of the variation in titratable acidity. Although lime requirement determined by the Shoemaker-Mc-Lean-Pratt procedure was very highly correlated with titratable acidity (r = 0.98), the data show that the estimated amount of lime to raise soil pH to 6.8 actually exceeded the total (titratable plus exchangeable) acidity in 19 of the 20 soils. Key words: Extractable Al, organic matter, SMP buffer, cation exchange capacity
FIELD TECHNIQUES USING THE ACETYLENE BLOCKAGE OF NITROUS OXIDE REDUCTION TO MEASURE DENITRIFICATION
Authors: BURTON D. L. , BEAUCHAMP E. C.
Published: March 2010

Four techniques for the measurement of denitrification rates in the field were compared. All involved the use of acetylene (C2H2) to block nitrous oxide (N2O reduction and subsequent measurement of accumulated N2O. Two extracted core techniques were compared with two in situ cylinder techniques. The single-wall cylinder technique involved partial insertion of a PVC tube into the soil, sealing the head-space, injection of C2H2 into the headspace and, after suitable time periods, assaying N2O concentration in the headspace. A double-wall cylinder technique was devised to allow more rapid C2H2 introduction into the soil core from an interwall space in situ. A comparison of the four techniques on a 1-m2 area in the field showed large spatial variability. Estimates of denitrification rates decreased in the order double-wall cylinder, single-wall cylinder, extracted encased core and extracted loose core. Variation among replicates varied between sampling occasions but, on aveage, decreased in the order single-wall cylinder, extracted encased core, extracted loose core and double-wall cylinder. Key words: Denitrification, field measurement techniques, acetylene blockage, spatial variability
CROP UTILIZATION OF PLACED AND BROADCAST 15N-UREA FERTILIZER UNDER ZERO AND CONVENTIONAL TILLAGE
Authors: CARTER M. R. , RENNIE D. A.
Published: March 2010

Growth chamber and field studies were conducted to assess the relative utilization of placed and broadcast 15N-urea by spring wheat. The field studies were conducted on zero and conventional (shallow) tillage systems, of 4-yr duration, located on Chernozemic soils at two locations in Saskatchewan. Placement below the seeding depth in comparison to broadcast application, generally reduced fertilizer N immobilization and increased fertilizer N uptake, recovery, and efficiency. Under moisture stress, placed applications were effective in enhancing dry matter yield and total N uptake. It is concluded that fertilizer N placement for these two contrasting tillage systems should be identical, thus some soil disturbance under zero tillage may be necessary to achieve optimum crop use of applied fertilizer N. The dominant N transformation processes and possible tillage induced differences, in regard to methods of N application, are discussed. Key words: Placed and broadcast N application, N efficiency, N utilization, 15N-urea, zero tillage, soil moisture
INFLUENCE OF DRAINAGE REGIME ON THE CHEMISTRY AND MORPHOLOGY OF SOME MANITOBA SOILS: SANDY CHERNOZEMIC AND GLEYSOLIC SOILS OF THE LOWER ASSINIBOINE DELTA
Authors: MICHALYNA W. , RUST R. H.
Published: March 2010

A number of imperfectly and poorly drained sandy soils from the Almasippi Association of the Lower Assiniboine Delta in Manitoba, traditionally classified as Gleyed Chernozems and Gleysols, were characterized by morhological descriptions, chemical and physical analyses. Soil temperature, groundwater levels, and redox potential of both soil and water were determined at selected sites for various periods to a maximum of 2 years. The upper 30 cm of the soils, traditionally considered as Gleysols, had undergone strong reducing conditions (100 to −200 mV) for at least 2 mo in the spring and early summer; these areas were covered with hydrophytic vegetation and remained saturated at or near surface to July. The subsoil below 45 cm remained in an oxidized state throughout the year. Exchangeable Ca/Mg ratio was near unity in the Gleysols and substantially greater in the Gleyed subgroups. Oxalate to dithionite-extractable iron ratios were greater than 0.45 in the lower part and below the solum of Gleysolic and Gleyed soils. In soils classified as Gleyed subgroups, water tables were below 1.3 m throughout the season and soil profiles were in an oxidized condition. Classification of these soils according to the present Canadian and U.S. system would require a change in concept and approach from the traditional view of Gleysolic soils in Canada. Key words: Redox potential, chemical criteria, morphological criteria, water table, soil temperature
EFFECT OF FERTILIZER ON SOIL pH AFTER 17 YEARS OF CONTINUOUS CROPPING IN SOUTHWESTERN SASKATCHEWAN
Authors: CAMPBELL C. A. , ZENTNER R. P.
Published: March 2010

Measurements of soil pH were made in the 0- to 2.5-cm, 2.5- to 7.5-cm, and 7.5-to 15-cm depths of a loam soil in two long-term (17 yr) continuous wheat rotations. One rotation received only ammonium phosphate fertilizer, while the other rotation received ammonium phosphate fertilizer plus ammonium nitrate fertilizer at an average rate of N of 35 kg∙ha−1∙yr−1. Soil pH was not measured at the start of the experiment. Measurements made at eight times between April and October 1983 showed that average pH in the surface 15 cm was lower in the rotation receiving N and P, compared to the one receiving only P, by about 0.5 pH units (pH 5.9 vs. 5.4 in dilute CaCl2). The soil pH varied considerably during the growing season and seemed to be inversely related to soil NO3-N. These pH changes occurred in a well buffered soil with CEC of 23.5 meq∙100 g−1. Scientists recommending that producers on the Prairies move to a more extended crop rotation so as to reduce land degradation, should bear in mind that eventually there may be a need to lime the soils to maintain production since such a system will necessitate the increased use of N fertilizers. Key words: pH changes during growing season, pH versus depth, soil acidity
SHORT-RANGE SOIL VARIABILITY AND CLASSIFICATION OF PODZOLIC PEDONS ALONG A TRANSECT IN THE LAURENTIAN HIGHLANDS
Authors: WANG C. , McKEAGUE J. A.
Published: March 2010

Pedons were described, sampled and classified at 5-m intervals along a 130-m transect in an area typical of the southern Laurentian Highlands in order to assess short-range soil variability. Orthic Ferro-Humic Podzol was the dominant subgroup (25 of 27 sites). Differences in depth to bedrock and in soil water regime resulted in four soil families; bedrock was exposed at one site. At 21 of the 27 sites, however, the pedons were classified in one family: Orthic Ferro-Humic Podzol, coarse loamy, cold, humid. Differences in thicknesses and sequences of horizons resulted in a total of at least nine soil series. At scales of 1:20 000 or somewhat smaller, the soils of map units in the area would be most appropriately indicated as slope phases (10–40% slopes) of families. The dominant family would be the one indicated above with inclusions of shallow to extremely shallow phases and bedrock outcrops. Key words: Soil variability, Podzolic soils, classification of pedons
DETERMINATION OF THE LIME REQUIREMENT FOR ACID SOILS IN ONTARIO USING THE SMP BUFFER METHODS
Authors: SOON Y. K. , BATES T. E.
Published: March 2010

The accuracy of the Shoemaker-McLean-Pratt single buffer method and its double buffer variation was compared for determining the lime requirement of 41 acid mineral soils in Ontario. The single buffer method gave good prediction of the lime requirement when calibrated against Ca(OH)2-titrated soil acidity using a quadratic equation. Key words: Lime requirement, acid soils, SMP buffer
RETENTION OF BORON BY AGRICULTURAL SOILS FROM ONTARIO
Authors: EVANS L. J.
Published: March 2010

The retention of B by 20 agricultural soils from Ontario was investigated by equilibration of the soils with various concentrations of boric acid. The retention of B conformed to both Langmuir and Freundlich adsorption isotherms for all but one soil. Adsorption maxima were calculated for both isotherms and from simple linear regression analysis only pH was found to be significantly correlated with the calculated adsorption maxima. For soils with pH above 6.8, the Langmuir adsorption maxima were significantly correlated with organic C and water-soluble carbohydrate contents. Application of phase diagrams indicated that, under the experimental conditions employed, the solutions of some of the acidic soils were supersaturated with respect to the Ca-containing borate minerals inyoite, colemanite and nobleite and, given a number of reasonable assumptions, that at rates of B application of 3 kg ha−1, acidic soils could be supersaturated with respect to the mineral nobleite. The extent of complexation of B with glucose was shown only to be important at pH in excess of 8. Key words: Boron, carbohydrates, inyoite, colemanite, nobleite, complexation
A NEW HAND TOOL FOR CUTTING SOIL MONOLITHS
Authors: WARDENAAR E. C. P.
Published: March 2010

A portable tool for cutting undisturbed soil monoliths has been developed and field tested. A soil column suitable for mounting or subsampling can be obtained in less than 5 min from all soils that are not excessively stony. Key words: Profile cutter, undisturbed samples
SOIL ANALYSIS AND NUMERICAL CLASSIFICATION OF THE LANORAIE DELTA, QUEBEC
Authors: LAMONTAGNE L. , CAMIRE C.
Published: March 2010

Analysis and numerical classification of Lanoraie Delta soils were performed as part of an ecological study. After stratification, using detailed soil maps, 84 forest sites were randomly sampled. Eighteen soil descriptors, mainly morphologic, were retained for numerical analysis. Gower's similarity coefficient between profiles was used for the principal coordinate analysis (PCA) which brought out the most probable factors governing soil distribution. The first two axes of the PCA represented 15.5 and 6.2% of the total variance. Soil distribution was along two gradients: soil water regime (Xeric-Hydric) and genetic development (Gleysolic-Podzolic). Cluster analysis by complete linkage created five soil groups which were composed of 23, 9, 17, 25 and 10 soil individuals, respectively. The interpretation of these soil groups utilized the superposition of clusters onto the first two axes of the PCA. Each group was classified into a taxonomic subgroup (Canadian System of Soil Classification) and defined by a typical humus form. Key words: Lanoraie Delta, multivariate analysis, soil classification
EFFECT OF Nosema locustae Canning (Microsporida) AND THREE CHEMICAL INSECTICIDES ON MICROBIAL ACTIVITY IN SOIL
Authors: GERMIDA J. J. , ONOFRIECHUK E. E. , EWEN A. B.
Published: March 2010

Nosema locustae Canning is a potential biological control agent for grasshoppers but some aspects of its environmental impact have not been investigated. This study assessed the impact of N. locustae and the chemical insecticides carbofuran, deltamethrin and dimethoate on microbial activity and nutrient cycling in soil. In a laboratory study, the insecticides were applied to a Haverhill loam at recommended field application rates and 10 times the field rates. There was no adverse effect from N. locustae or the chemical insecticides on any of the measured parameters. Analysis of field soils 6 wk after application of a mixture of N. locustae and dimethoate indicated this treatment had no adverse impact on microbial activity. Key words: Nosema locustae, carbofuran, deltamethrin, dimethoate, microbial activity
CINÉTIQUE ET MÉCANISME DE L'HYDROLYSE ACIDE DE LA MATIÈRE ORGANIQUE D'UN SOL HUMIFÈRE DE MONTAGNE
Authors: BARRIUSO E. , PORTAL J. M. , ANDREUX F.
Published: March 2010

From the surface horizon of an organic-rich mountain soil, humic and fulvic acids, and organo-mineral compounds including clay and hydroxy-metal colloids, were separated and purified. Each of these fractions was hydrolyzed in 3.0 M HCl under reflux, then the reaction parameters related to the solubilization of carbon and nitrogen and to the kinetics of hydrolysis were calculated. Acid hydrolysis was interpreted as the result of two successive steps: first a rapid electrophilic attack of heteroatomic C-O and C-N bonds by protons, then a slow nucleophilic hydration of the protonated bonds. Electron delocalization in these bonds, which increased with the polycondensation degree of organic compounds, and with their adsoprtion on mineral surfaces, resulted in an increase in their stability to hydrolysis. Fulvic acids were found to be the less stable material, and lead to predominantly anionic hydrolysis products. Clay-sized humin was the most stable material and yielded mainly cationic hydrolysates. The stability to hydrolysis and the humification degree of organic matter in the fractions generally coincided, and decreased in the following order: fine clay-sized humin > alkali dispersible organo-mineral colloids > > humic acids > hydroxy-ferric organic colloids > hydroxy-aluminium organic colloids = fulvic acids. Key words: Organo-mineral complex, humic substances, acid hydrolysis, carbon, nitrogen
SOIL EROSION AND CORN YIELD IN ONTARIO. I. FIELD EVALUATION
Authors: BATTISTON L. A. , MILLER M. H. , SHELTON I. J.
Published: March 2010

Yield of corn (Zea mays L.) was measured at eight sites in 1982 and nine sites in 1983 on areas in farm fields exhibiting differing degrees of past erosion. Yield was also measured on depositional areas in some fields. Yield on depositional areas was, on average, marginally greater than on noneroded areas. Yield on severely eroded areas (all or most of original solum lost) ranged from 16 to 80% of that on noneroded areas with an average of 59%. There was little or no reduction in yield until the depth to Ck had been reduced to almost 50% of that on the noneroded profile. With further reductions in depth to Ck, yields declined rapidly on most sites. The primary cause of yield reduction varied from site to site and included reduced stand and seedling vigor due to a poor seedbed condition, nutrient deficiency and reduced available water holding capacity (AWHC). The impact of erosion on yield at a field and regional level was estimated based on the extent of erosion determined from aerial photographs and the site-specific yield measurements. Estimated corn yield on two fields was about 92% of that expected if no erosion had occurred. In a 90-km2 area of the Regional Municipality of Waterloo, 18% of the cultivated land was estimated to be moderately to severely eroded. Based on the site-specific yield measurements, this erosion would result in a 3.6% reduction in average corn yield in the region. The implications of the findings on preventative and remedial measures and on future productivity in the region are discussed. Key words: Erosion, yield, corn, seedbed condition, nutrient deficiency, water stress
PERSISTENCE OF CHANGES IN SELECTED SOIL CHEMICAL AND PHYSICAL PROPERTIES AFTER PIPELINE INSTALLATION IN SOLONETZIC NATIVE RANGELAND
Authors: NAETH M. A. , BAILEY A. W. , McGILL W. B.
Published: March 2010

A study was conducted in Solonetzic mixed prairie of southern Alberta to evaluate and determine the longevity of selected ecosystem responses to pipeline installation. Five adjacent natural gas pipelines on a series of rights-of-way (ROW) were studied at three sites. The lines, which were installed in 1957, 1963, 1968, 1972 and 1981, had diameters of 86, 86, 91, 107 and 107 cm, respectively. Soils were analyzed for particle size distribution, bulk density, pH, electrical conductivity, ion composition, and organic matter content. It was concluded that pipeline construction in Solonetzic mixed prairie range-land initially tended to improve surface soil chemical and physical properties compared to blowouts, but reduced soil quality in vegetated native prairie. Surface bulk density increased to 1.3–1.6 Mg m−3 from an undisturbed density of 0.9–1.0 Mg m−3. Increased densities were evident to 55 cm in all 1981 transects except the trench where subsurface densities were reduced. Chemical changes were associated with reduced organic matter and increased salts at the surface. On the basis of differences between the various ages of pipelines (1981, youngest; 1957, oldest) there was evidence for greater amelioration of chemical changes than of physical disturbances over time. The time needed to restore half the lost organic matter was estimated to be approximately 50 y. Key words: Pipeline, Solonetzic soil, rangeland (native), soil chemistry, bulk density, reclamation
PORE VOLUME CHANGES IN A STRUCTURED SILT-LOAM SOIL DURING DRYING
Authors: WIRES K. C. , ZEBCHUK W. D. , TOPP G. C.
Published: March 2010

Shrinkage and volumetric water content of undisturbed soil cores 150 mm diam. × 100 mm high from four horizons of a silt-loam, Orthic Humic Gleysol were monitored throughout a drying cycle from saturation to oven dryness. Drying from saturation to − 100 kPa was by desorption apparatus. Subsequently the cores were subjected to controlled air drying and finally oven drying. The volume change, relative to the volume at saturation, of each core was monitored at 20 different water contents on the desorption curve, by measuring the X, Y and Z positions of 92 pins inserted in the top of each core. Total shrinkage values expressed as percentages of the cores' saturated volumes were Ap −23.4%, Bg −7.0%, BCg −11.8% and Cg −12.9%. The influence of soil structure on soil shrinkage was analyzed and the results were inconclusive because there appeared to be a complex interaction between ped size and the scale of measurement for shrinkage. Water loss during drying was partitioned between that replaced by air and that associated with pore volume reduction. For the Ap horizon from 0 to 1500 kPa, the proportions were 62% and 38% respectively. The results show clearly the dependence of soil bulk density and porosity on water potential and reinforce the contention that for comparison purposes bulk density and porosity must be expressed at a reference water content or potential. Key words: Shrinkage, pore volume, bulk density, undisturbed samples
PODZOLIC SOIL DEVELOPMENT IN THE SOUTHERN JAMES BAY LOWLANDS, ONTARIO
Authors: PROTZ R. , SHIPITALO M. J. , ROSS G. J. , TERASMAE J.
Published: March 2010

Nine soil profiles from a 52-km-long transect orthogonal to the coast of Southern James Bay range in age from 1000 to 3000 yr. The depth of carbonate leaching, mass of vermiculite clay formation, profile organic matter and amorphous material (Fe, Al and Si) accumulation were determined. Rates of these pedogenetic processes were calculated, and compared to rates in a cooler, drier area on the Hudson Bay Coast. The rates are about twice as rapid in the southern James Bay area as in the Hudson Bay Coastal zone. These differences in rates are explained on the basis of mean annual temperature and precipitation. Key words: Vermiculite, carbonate leaching, rates of pedogenesis
ULTRASONIC DISPERSION OF AGGREGATES: DISTRIBUTION OF ORGANIC MATTER IN SIZE FRACTIONS
Authors: KACHANOSKI R. G. , VORONEY R. P. , GREGORICH E. G.
Published: March 2010

Aggregates (1–2 mm) from a soil under continuous corn management were subjected to a mild shaking treatment and ultrasonic energy levels ranging from 100 to 1500 J mL−1 water to determine the degree of aggregate disruption and dispersion. More clay- and fewer sand-size particles were recovered with greater amounts of applied energy indicating greater aggregate disruption and dispersion with higher energy levels. Most of the breakdown of sand-size aggregates occurred between energy levels of 300 and 500 J mL−1. Ultrasonic energy levels of 500 J mL−1 or greater were more effective than using 20% hydrogen peroxide plus 16 h of shaking in dispersing sand-size microaggregates. Surface area measurements of the clay indicated no severe fragmentation or alteration of primary particles had occurred. With increased applied ultrasonic energy and more complete dispersion, the amount of organic C recovered increased in the clay- and decreased in the sand-size fractions. At complete dispersion, there was no evidence of redistribution of organic matter by ultrasonification and the sand-, silt- and clay-size fractions contained 5, 30 and 60% of the soil organic C. Results of this study suggest that ultrasonic dispersion techniques can be used as a physical method to separate microaggregates from soil and thereby study the nature of organic matter within them. Key words: Ultrasonic dispersion methodology, aggregates, organic matter distribution, particle size fractions
WINTER WHEAT GROWTH IN ARTIFICIALLY COMPACTED SOIL
Authors: WILHELM W. W. , MIELKE L. N.
Published: March 2010

Dense soil tillage pans can develop from the improper use of tillage tools. The influence of compacted layers or pans on plant growth and development, although much studied, is not clearly understood. This greenhouse experiment evaluated the influence of uniformly compacted soil and thin layers of compacted soil placed at various depths on early growth of winter wheat (Triticum aestivum L.). Artificially compacted soil [Alliance silt loam, Aridic Argiustoll (Eluviated Brown Chernozem); A horizon] profiles were constructed in polyvinyl chloride tubes of 150-mm diameter by 350 mm long. Treatments were: (1) uniformly noncompacted (bulk density 1.30 Mg m−3) soil; (2) uniformly compacted (bulk density 1.80 Mg m−3) soil; (3) a compacted (bulk density 1.80 Mg m−3) soil layer at 100- to 120-mm depth with the remaining soil noncompacted (bulk density 1.30 Mg m−3); or (4) a compacted (bulk density 1.80 Mg m−3) soil layer at 180- to 200-mm depth with the remaining soil noncompacted (bulk density 1.30 Mg m−3). Generally, winter wheat grown in cores that were uniformly compacted or compacted in the upper layer responded similarly. Plant height, at the end of the experiment (32 d after planting), for the uniformly compacted and upper compacted layer treatments was 280 mm, compared to 323 mm for the control (uniformly noncompacted). Leaf area development was similar to the response indicated for plant height throughout the growth period. Root mass and length tended to be less in layered or compacted soil than in noncompacted soil. Roots accumulated within or immediately above compacted soil layers. Higher bulk density or a shallow compacted layer produced winter wheat with reduced height, leaf area, and dry matter compared with soil of normal density or with a deeper compacted layer. Key words: Bulk density, Triticum aestivum L., tillage pan, wheat (winter)
YIELD AND N2 FIXATION OF PEA AND LENTIL AS AFFECTED BY INTERCROPPING AND N APPLICATION
Authors: COWELL L. E. , BREMER E. , KESSEL C. VAN
Published: March 2010

Farmers in Saskatchewan have recently begun intercropping pea with nonlegumes in order to reduce lodging of the pea crop and thus improve harvesting operations. The response of pea and lentil to intercropping and N application was determined at five locations throughout Saskatchewan in 1987. At each site one of the following combinations was tested: lentil and flax, pea and rape, pea and yellow mustard or pea and oats. All treatments received 10, 30 or 50 kg N ha−1 as urea. Nitrogen-15 microplots were included to measure N2-fixation and percent fertilizer use efficiency (% FUE). Intercropping reduced lodging and improved harvesting conditions of pea and lentil. An increase in the land equivalent ratio (LER) due to intercropping was observed at two sites where growing conditions were poorer than at the other three sites. At the other sites intercropping systems had a similar or intermediate % FUE to that of the monocropped legume and non-legume. Percent N derived from N2-fixation (% Ndfa) ranged from 4.6 to 87.6, depending on site, level of N application and cropping system. Intercropped legumes had a significantly higher % Ndfa than monocropped legumes at two sites. Nitrogen fertilization reduced the % Ndfa of monocropped legumes at two sites but never affected the % Ndfa of intercropped legumes. Total N2 fixed was almost always less in intercropped than in monocropped systems, although only significantly at two sites. No significant lower values for atom % 15N of intercropped non-legumes as compared with monocropped non-legumes were observed, indicating that transfer of N from the legume to the non-legume was minimal. Key words: Intercropping, monocropping, flax, lentil, rape, pea, yellow mustard, oat
THE EFFECT OF ZINC RATE AND PLACEMENT ON YIELD AND ZINC UTILIZATION BY BLACKBEAN (Phaseolus vulgaris var. Black Turtle)
Authors: SOPER R. J. , MORDEN G. W. , HEDAYAT M. W.
Published: March 2010

Growth chamber experiments were conducted to investigate the effect of size of fertilizer reaction zone, rate of added zinc and method of placement of added zinc on the dry matter yield, zinc concentration and zinc uptake of blackbeans grown on a calcareous soil. Relationships between zinc concentrations in the plant, zinc utilization by the plant and zinc concentration in the soil reaction zone were obtained. An equation was developed relating zinc utilization to zinc concentration in the fertilizer band, and a figure was derived showing how increasing the size of the fertilizer zone impacts upon the zinc concentration of the plant. The results indicate that inorganic zinc fertilizers must be mixed as uniformly as possible for maximum effectiveness. Key words: Zinc, placement, calcareous, soil, blackbean, Phaseolis vulgaris
EFFECT OF LONG-TERM MINIMUM TILLAGE PRACTICES ON SOME PHYSICAL PROPERTIES OF A CHERNOZEMIC CLAY LOAM
Authors: CHANG C. , LINDWALL C. W.
Published: March 2010

This study was conducted to compare the long-term (20 yr) effects of conventional tillage, minimum tillage and no-till on various soil-water related properties within the tilled layer (0–30 and 30–60 mm) and immediately below the tilled layer (90–120 mm) under a spring cereal-summerfallow rotation cropping system. Parameters measured included saturated hydraulic conductivity, saturation percentage, plant-available water-holding capacity, large pore porosity, bulk density, and infiltration rate of the soil. Tillage treatment effects on these soil properties in each of the four sampling periods were not significantly different. The confidence interval test showed some temporal changes in these soil physical properties, of which hydraulic conductivity was the most affected. In the summerfallow field, regardless of the previous cereal crops, the steady infiltration rate was significantly lower in the soil under conventional tillage than with that under no-till. The results indicate that the surface soil structure was most stable under no-till. In the fresh stubble field, the type of cereal crop had an effect on the infiltration rate of the soil. The mean infiltration rate was higher in the summerfallow field than in the fresh stubble field and also was higher in the fresh barley stubble than in the fresh wheat stubble. Except for infiltration rates, there is no significant advantage of one tillage method over the other with respect to the soil physical properties measured in this Brown Chernozemic clay loam soil. Key words: No-till, minimum tillage, hydraulic conductivity, bulk density, infiltration
THE INFLUENCE OF Zn AND P FERTILIZER ON THE DRY MATTER YIELD AND NUTRIENT CONTENT OF FLAX (Linum usitatissimum L.) ON SOILS VARYING IN Ca AND Mg LEVEL
Authors: GRANT C. A. , BAILEY L. D.
Published: March 2010

Flax (Linum usitatissimum L.) was grown in two growth chamber experiments on a total of 16 Black Chernozemic soils varying in content of Mg, Ca, P, and Zn. On three of the soils, dry matter yield of flax increased in response to application of P. Phosphorus availability was greater with broadcast than with banded fertilizer applications. Increased yield in response to Zn application was observed on one-half of the soils. Applications of P that increased P level in the tissue above 0.46% led to consistent but nonsignificant decreases in yield and reduced the level of Zn in the tissue. Zinc fertilization increased Zn and decreased P level in the tissue. Yield response to P application was not strongly related to soil chemical parameters measured, but increased as tissue P level decreased and tissue Zn level increased. High levels of soil Mg and soil pH and high tissue levels of Mg and P were the factors most closely associated with a yield response to Zn applied with P. Key words: Flax, Linum usitatissimum, Ca, Zn, P, Mg, fertilizer placement
A PROBE FOR MEASURING DEPTH TO WATER SURFACE IN WELLS
Authors: BODLEY C. L. , JEGLUM J. K. , BERRY G. J.
Published: March 2010

Plans are presented for the construction of a probe for measuring depth to water surface in water wells. The probe utilizes a battery-powered audible buzzer and a light-emitting diode. The probe is cheap, simple to construct, and durable enough for extended field use in forest and peatland hydrology studies. Key words: Water wells, depth probe, electronic circuitry, audible buzzer, peatland, hydrology
UPTAKE OF NATURAL RADIONUCLIDES BY FIELD AND GARDEN CROPS
Authors: SHEPPARD S. C. , EVENDEN W. G. , POLLOCK R. J.
Published: March 2010

Natural radionuclides of the uranium (U) and thorium (Th) decay series contribute to the radiation dose received by humans. In the context of U mining and refining, it is important to accurately assess the pathway for these radionuclides from soils to food plants. The Canadian Standards Association model of this pathway for dose estimation is based on the plant/soil concentration ratio (CR). In a controlled outdoor lysimeter setting, we measured CR values for experimentally applied U at 100 mg kg−1, 230Th at 8 kBq kg−1 and 210Pb (lead) at 20 kBq kg−1 using a sand, a loam, a clay and an organic soil in 12 soil and crop combinations. The overall geometric mean CR values were 0.013, 0.0022 and 0.0050 for U, 230Th and 210Pb, respectively. A second experiment using one soil and crop showed CR to be dependent on soil concentration for U, but not for Th and Pb. The final two experiments dealt with uptake of U, Th, Pb, Ra (radium), Cs (cesium), Po (polonium), and As (arsenic) from soils contaminated by a former Ra processing facility, both in a controlled lysimeter setting and in uncontrolled home-garden settings. The results generally agreed with those of the initial experiment, although the overall geometric mean CR for Th was higher at 0.02. Most of the recommended Th CR values for dose estimation are tenfold below those for U; our garden-setting results suggest they should be equal or higher. The effects on soil properties and crop type on CR values are discussed. Key words: Concentration ratio, uranium, thorium, lead
QUICK-MOUNT SOIL CORE SAMPLER FOR MEASURING BULK DENSITY
Authors: TESSIER S. , STEPPUHN H.
Published: March 2010

The design for a sleeve-type, quick-mount soil core sampler for bulk density and soil water content determination and for collection of undisturbed soil samples is described and its performance discussed. This core sampler has been used to collect undisturbed soil core samples 47.5 mm in diameter and 300 mm long in tillage and seeding studies. Less than 2 min is required to retrieve, seal and store each soil core sample. The soil samples are contained in 50.8-mm-diameter aluminum liners which are easily sealed with plastic caps and stored for later laboratory analysis. This sampler resulted in very good measurement repeatability and provided subsamples suitable for water retention curve determinations. Key words: Soil sampler, coring device, bulk density, soil moisture, undisturbed cores
DIFFERENTIAL FERTILIZER N IMMOBILIZATION IN TWO TILLAGE SYSTEMS INFLUENCES GRAIN N CONCENTRATION
Authors: CAREFOOT J. M. , LINDWALL C. W. , NYBORG M.
Published: March 2010

Differential N immobilization between conventional tillage (CT) and no-till (NT) systems has been suggested as a possible mechanism for differences in crop response to N. To examine this effect, immobilization of N fertilizer was compared in NT and CT cereal production systems at two sites in southern Alberta (Lethbridge and Vauxhall) from 1983 to 1985. Fertilizer N, labelled with 15N, was applied at rates ranging from 25 to 50 kg N ha−1 to winter wheat (Triticum aestivum L. 'Norstar'), barley (Hordeum vulgare L. 'Galt'), or spring wheat (Triticum aestivum L. 'Chester') in various rotations. Nitrogen immobilization was subsequently quantified by 15N analysis of crop tissues and soil N fractions. The amount of N immobilized was strongly influenced by climatic variables. In 1984, characterized by drought in the spring but significant precipitation during June, mean N immobilization losses for winter wheat and barley in the CT treatments averaged much less than those in NT treatments (20 vs. 34% of N applied). Conversely, in 1985, which was characterized by a wet spring and a very dry summer, N immobilization losses were comparable in the two barley tillage treatments (mean = 29% of N applied). Lack of precipitation early in the season appears to restrict immobilization less in CT than in NT treatments because of greater fertilizer-residue contact in the latter. Despite the trends in immobilized N, grain yields were often higher in the NT than in the CT treatments, indicating that yield differences were likely related to the availability of moisture rather than to N fertility. Restricted N availability resulting from immobilization losses, however, reduced grain N concentration in NT relative to CT treatments. Key words: No-till, conventional till, N immobilization, N response, residual N
EFFETS DE L'APPORT PROLONGE DE FUMIER DE BOVINS SUR QUELQUES PROPRIETES PHYSIQUES ET BIOLOGIQUES D'UN LOAM LIMONEUX NEUBOIS SOUS CULTURE DE MAÏS
Authors: N'DAYEGAMIYE A. , ANGERS D. A.
Published: March 2010

This study was undertaken to quantify the effects on long-term application of solid cattle manure on physical and biological properties of a Neubois silty loam. Rates of 0, 20, 40, 60, 80 and 100 Mg ha−1 manure were applied every 2 yr to the soil cropped to corn. Significant improvements, proportional to application rates, of water-stable aggregation, bulk density, and water content of the soil were measured. These physical properties were highly correlated with the soil microflora (0.83 ≤ r ≤ 0.98). A positive interaction exists between physical and biological properties of soils following long-term manure application. Key words: Solid cattle manure, aggregation, bulk density, biological activity
DEGRADATION STUDIES WITH 14C-FENOXAPROP IN PRAIRIE SOILS
Authors: SMITH A. E. , AUBIN A. J.
Published: March 2010

The persistence of 14C-fenoxaprop acid, the major degradation product of the herbicide 14C-fenoxaprop-ethyl, was studied at different controlled temperature and moisture conditions in three Saskatchewan soils. At 85% of field capacity, degradation approximated to first-order kinetics at soil temperatures of 10, 20, and 30 °C, with half-life values ranging from 42 to 5 d. In a clay at 20 °C, there was no effect of moisture, between 50% and 100% field capacity, on the rate of 14C-fenoxaprop acid breakdown. There was no loss of radioactivity after 65-d in air dry soils. In all soils incubated at 85% field capacity and 20 °C with 14C-fenoxaprop-ethyl, uniformly labeled in the chlorophenyl ring, there was evolution of 14CO2 indicating ring fission. Over a 56-d incubation period, 10–15% of the applied radioactivity was released from the treated soils as 14CO2. Extraction with ammoniated acetonitrile recovered 14–19% of the original radioactivity; between 3 and 5% of the initial 14C was incorporated into soil microbial biomass; and 17–25% into the fulvic acid, 7–12% into the humic acid, and 30–34% into the humin soil fractions. Key words: Herbicide, biomass, fenoxaprop-ethyl, fenoxaprop, persistence
ÉTUDE COMPARATIVE DE L'AGRÉGATION ET DE LA MATIÈRE ORGANIQUE ASSOCIÉE AUX FRACTIONS GRANULOMÉTRIQUES DE SEPT SOLS SOUS CULTURE DE MAÏS OU EN PRAIRIE
Authors: ELUSTONDO J. , LAVERDIÈRE M. R. , ANGERS D. A. , N'DAYEGAMIYE A.
Published: March 2010

Water-stable aggregation and organic matter associated with particle-size fractions were compared for seven pairs of soils that were either under meadow or continuous corn cropping for more than 5 yr. Soils that have remained under meadow contained 25 and 29% more carbon and nitrogen than those under continuous corn. Carbon contents of the sand- and silt-size fractions were also 61 and 15% higher, respectively, under meadow than under continuous corn. The cropping system had no significant effect on the carbon and nitrogen contents of the clay-size fractions. The amount of water-stable aggregates (> 1 mm) was on average 34% higher in soils under meadow than in soils under corn cropping. Significant correlations were found between water-stable aggregates and total C (r = 0.77) and C in sand-size fraction (r = 0.79). The results also indicate that the beneficial effect of meadow over continuous corn on soil aggregation increases as soil clay content increases. Key words: Aggregation, organic matter, particle-size fractions, corn, meadow
INFLUENCE OF ICE SEGREGATION AND SOLUTES ON SOIL STRUCTURAL STABILITY
Authors: PERFECT E. , LOON W. K. P. van , KAY B. D. , GROENEVELT P. H.
Published: March 2010

Most Canadian soils contain dissolved salts and are subject to freezing. However, the structural consequences of freezing in the presence of solutes are unknown. The effects of ice segregation and solutes on soil structural stability were investigated in a laboratory experiment. Nine 27-cm-diameter by 19-cm-high columns were used. These were packed with air-dry Conestogo silt loam soil (Gleyed Melanic Brunisol or Aquic Eutrochrept) and wetted with CaCl2 solutions at 1, 2, and 4 g L−1. Slow freezing took place from the top down in an environmental chamber maintained at −3.4 ± 0.4 °C. Depth of frost penetration, temperature, frost heave, and unfrozen water content were monitored within each column. After 20 d, the mean frost penetration was 107 ± 18 mm and the soil surface had heaved 9 ± 4 mm, indicating ice segregation. At the end of the experiment, the frozen and unfrozen zones of each column were sampled destructively. Samples were equilibrated at 4 °C and analyzed for wet-aggregate stability (WAS), dispersible clay (DC), gravimetric water content, and CaCl2 concentration. Samples which had been frozen had significantly more water and CaCl2 in the thawed state than those which had remained unfrozen. These increases were attributed to a freezing-induced redistribution of the saturating solutions. DC decreased with increasing CaCl2 concentration, indicating an electrical double-layer effect. Soil that had been frozen and thawed had a more stable structure (in terms of both DC and WAS) than the unfrozen soil. No interaction was found between solutes and freezing. In contrast, there was a significant interaction between water content and freezing. WAS increased with decreasing water content for those aggregates which had been frozen and thawed, but not for those which had remained unfrozen. Key words: Soil structure, wet-aggregate stability, dispersible clay, frost heave, soil solution, bulk electrical conductivity
Measuring Progressive Independence With the Resident Supervision Index: Empirical Approach
Authors: Kashner T. Michael , Byrne John M. , Chang Barbara K. , Henley Steven S. , Golden Richard M. , Aron David C. , Cannon Grant W. , Gilman Stuart C. , Holland Gloria J. , Kaminetzky Catherine P. , Keitz Sheri A. , Muchmore Elaine A. , Kashner Tetyana K. , Wicker Annie B.
Published: March 2010

Background

A Resident Supervision Index (RSI) developed by our research team quantifies the intensity of resident supervision in graduate medical education, with the goal of testing for progressive independence. The 4-part RSI method includes a survey instrument for staff and residents (RSI Inventory), a strategy to score survey responses, a theoretical framework (patient centered optimal supervision), and a statistical model that accounts for the presence or absence of supervision and the intensity of patient care.

Methods

The RSI Inventory data came from 140 outpatient encounters involving 57 residents and 37 attending physicians during a 3-month period at a Department of Veterans Affairs outpatient clinic. Responses are scored to quantitatively measure the intensity of resident supervision across 10 levels of patient services (staff is absent, is present, participated, or provided care with or without a resident), case discussion (resident-staff interaction), and oversight (staff reviewed case, reviewed medical chart, consulted with staff, or assessed patient). Scores are analyzed by level and for patient care using a 2-part model (supervision initiated [yes or no] versus intensity once supervision was initiated).

Results

All resident encounters had patient care supervision, resident oversight, or both. Consistent with the progressive independence hypothesis, residents were 1.72 (P  =  .019) times more likely to be fully responsible for patient care with each additional postgraduate year. Decreasing case complexity, increasing clinic workload, and advanced nonmedical degrees among attending staff were negatively associated with supervision intensity, although associations varied by supervision level.

Conclusions

These data are consistent with the progressive independence hypothesis in graduate medical education and offer empirical support for the 4-part RSI method to quantify the intensity of resident supervision for research, program evaluation, and resident assessment purposes. Before informing policy, however, more scientific research in actual teaching settings is needed to better understand the relationships among patient outcomes, clinic workload, case complexity, and graduate medical education experience in resident supervision and professional development.
Contextualizing SEGUE: Evaluating Residents' Communication Skills Within the Framework of a Structured Medical Interview
Authors: Skillings Jared Lyon , Porcerelli John H. , Markova Tsveti
Published: March 2010

Background

The SEGUE (Set the stage, Elicit information, Give information, Understand the patient's perspective, and End the encounter) Framework is a checklist-style rating scale to facilitate the teaching and assessment of communication skills in medical learners. It has been used for over 15 years, and it is recommended in the Accreditation Council for Graduate Medical Education toolbox of assessment methods for resident training. When it was developed, its ability to provide objective scoring was a substantial improvement over global ratings.

Methods

In this article we describe the strengths and weaknesses of the SEGUE Framework. We highlight one residency program's experience with using the SEGUE Framework to evaluate residents' communication skills. Specifically, we cite previous studies and describe our own analysis of resident interviewing performance that demonstrates how the SEGUE Framework did not distinguish between different levels of interviewing skill level in our sample.

Results

Two case examples illustrate how the SEGUE Framework is not an ideal instrument to measure either the quality or the process of medical interviews.

Conclusion

Therefore, we propose a new method of contextualized assessment that builds on the SEGUE Framework. Our system evaluates discrete interviewing behaviors within the context of an ambulatory medical interview. We describe our interview structure, as well as a new instrument (the Wy-Mii, pronounced “why me”), to assess both communication and interpersonal skills. We expect that our new method of contextualized assessment will better differentiate between beginning and advanced levels of medical interviewing skills for residents.