bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPARISON OF METHODS FOR DETERMINING SATURATED HYDRAULIC CONDUCTIVITY AND DRAINABLE POROSITY OF TWO SOUTHERN ALBERTA SOILS
Authors: BUCKLAND G. D. , HARKER D. B. , SOMMERFELDT T. G.
Published: March 2010

Saturated hydraulic conductivity (Ks) and drainable porosity (f) determined by different methods and for different depths were compared with those determined from the performance of drainage systems installed at two locations. These comparisons were made to determine which methods are suitable for use in subsurface drainage design. Auger hole and constant-head well permeameter Ks were 140 and 110%, respectively, of Ks determined from subsurface drains. Agreement of horizontal or vertical Ks, from in situ falling-head permeameters; to other methods was satisfactory providing sample numbers were large. Ks by Tempe cells was only 3–10% of drain Ks and in one instance was significantly lower than Ks determined by all other methods. At one site a profile-averaged value of f determined from the soil moisture characteristic curve (0–5 kPa) of semidisturbed cores agreed with that determined from drainage trials. At the other site, a satisfactory value of f was found only when the zone in which the water table fluctuated was considered. Results indicate that Ks determined by the auger hole and constant-head well permeameter methods, and f determined from the soil moisture characteristic curve of semidisturbed cores, are sufficiently reliable and practical for subsurface drainage design. Key words: Subsurface drainage, hydraulic conductivity, drainable porosity
ABSORPTION OF P BY CORN (Zea mays L.) AS INFLUENCED BY SOIL DISTURBANCE
Authors: O’HALLORAN I. P. , MILLER M. H. , ARNOLD G.
Published: March 2010

In 1981, phosphorus absorption by young corn (Zea mays L.) plants was greater from no-till than from plowed plots with similar NaHCO3-extractable P (Ext P) concentrations. A series of growth room studies was conducted to explain this difference. Corn plants grown on cores from the no-till plots had a higher P concentration than plants grown on soil from the plowed plots, in spite of a lower root growth and a lower Ext P content. Disturbance of the no-till soil eliminated the effect. A parameter, accessible P (Acc-P), was calculated from root length and Ext P assuming P was absorbed from a cylinder of soil around each root. Shoot P content at a given Acc-P content was always higher with the undisturbed no-till soil than with either the disturbed no-till or the plowed soil. Irradiation (γ-ray) of the no-till soil reduced P absorption by a similar degree to disturbance, indicating that a biological factor was involved. Disturbance of soil had no influence on P content of canola (Brassica napus L.), a nonmycorrhizal crop. Soil disturbance reduced the intensity of mycorrhizal infection in corn roots. It is hypothesized that disturbance of the no-till soil reduced P absorption by reducing the effectiveness of the mycorrhizal symbiosis. Key words: No-till, corn, P absorption, mycorrhizae
EFFECT OF EXCESS FEEDLOT MANURE ON CHEMICAL CONSTITUENTS OF SOIL UNDER NONIRRIGATED AND IRRIGATED MANAGEMENT
Authors: DORMAAR J. F. , SOMMERFELDT T. G.
Published: March 2010

A long-term field experiment was initiated in 1973 to determine the safe loading capacity of a Lethbridge loam (Dark Brown Chernozemic) with feedlot manure. The effect of 10 yr of feedlot manure loading was examined by analyzing a number of inorganic and organic matter constituents of the Ap horizon. Although soil C, P, and enzyme activities increased as feedlot manure additions to the soil increased, these increases diminished at triple the recommended loading regimes. Phosphatase activity was checked by increased labile phosphorus levels. Levels of adenosine 5′-triphosphate increased but fluctuated with time under various moisture regimes. The C:N ratios, percent monosaccharide C of total soil C, and the ratio of deoxyhexoses to pentoses remained constant while the percentage of manure C retained decreased as feedlot manure loading increased. The distribution between pentoses and hexoses was strongly affected by feedlot manure levels while the deoxyhexose percentage of the sum of the eight monosaccharides determined remained about the same. Feedlot manure additions, at triple the recommended level, increased the labile P as a percentage of total soil P to around 50%. Although mineralization did not keep pace with the quantities applied, the presence of undecomposed manure did not seem to have harmful agronomic effects. Key words: ATP, feedlot manure, labile phosphorus, monosaccharides, organic matter
INCREASE IN MINERAL N IN SOILS DURING WINTER AND LOSS OF MINERAL N DURING EARLY SPRING IN NORTH-CENTRAL ALBERTA
Authors: MALHI S. S. , NYBORG M.
Published: March 2010

Ten field experiments were conducted on cultivated soils in north-central Alberta to determine any change in mineral N content of soils during winter, and during early spring after the soils had thawed. Soil samples were taken periodically from fall to spring to a depth of 120 (or 90) cm and were analyzed for NH4-N and for NO3-N. Mineral N changes occurred primarily in the top 60 cm. Between fall and late winter, there was an increase of 48 kg N ha−1 of mineral N (range of 27–83) in the 60-cm depth of eight experiments set on stubble and the value increased only to 55 kg N ha−1 when the sampling depth was extended to 120 (or 90) cm. Considering only the values from soil samples taken when soils were frozen, the increase in mineral N was 31 kg N ha−1 (range of 14–54) in the 120-cm depth, and the average net mineral N accumulation was 0.35 kg N ha−1 d−1 (range of 0.26–0.43). There was a loss of mineral N during early spring of 44 kg N ha−1 (range of 18–71). The two experiments on summerfallow had more over-winter accumulation of mineral N and more loss in early spring compared to the stubble experiments. This study showed large increases in the mineral N content when the soil was frozen and large decreases in the early spring. The mechanism of increase in mineral N in frozen soil was not determined. The cause of the decrease in early spring was most likely denitrification, and was not leaching of nitrate. The results of the investigation may have implications for the time of soil test sampling and for the loss of native N from cultivated soils. Key words: Ammonium N, frozen soil, mineral N, nitrate N, early spring loss
MICROBIAL RESPONSE TO SETHOXYD1M AND ITS DEGRADATION IN SOIL
Authors: ROSLYCKY E. B.
Published: March 2010

This inquiry concerned microbial response to sethoxydim, a newly registered post-emergence herbicide, and its persistence in soil. Recommended and lower sethoxydim (2[1-(ethoxyimino)butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexen-1-one) concentrations, ranging from 1 to 50 μg g−1 of active ingredient (a.i.) had little effect on soil microflora in a sandy loam, while 1000 μg g−1 a.i. caused approximately a tenfold increase in the actinomycete and bacterial populations and only slight suppression in that of fungi. None of the 359 actinomycete and only 30 of 455 bacterial soil isolates tested for sensitivity by replica plating were inhibited by 2000 μg a.i. of sethoxydim mL−1. Similarly, of the 239 pure cultures of 44 species tested, only 38 were inhibited by up to 2000 and 108 by 5000 μg a.i. of sethoxydim mL−1. Inhibition of respiration was generally dose-related and increasing as follows: actinomycetes < fungi < total microbiota < bacteria. Low doses produced inconsistent stimulation and retardation of O2 uptake. Differences in the response to the herbicide indicated physiological heterogeneity within the groups studied. The degradation reached the "half-life" in approximately 25 d but root inhibition by 1 and 5 μg a.i. of sethoxydim g−1 of the soil continued for about 150 and 280 d, respectively, indicating potential danger of cumulative effects of this herbicide and/or its breakdown products. Key words: Sethoxydim, microorganisms, respiration, degradation, accumulation, inhibitions
EFFECTS OF TILLAGE AND AMENDMENTS ON YIELDS AND SELECTED SOIL PROPERTIES OF TWO SOLONETZIC SOILS
Authors: WEBSTER G. R. , NYBORG M.
Published: March 2010

Five tillage treatments in combination with two amendments and two crops were established on two Solonetzic sites and continued for 6 yr. Simulated deep plowing significantly [Formula: see text] reduced SAR values for the 0- to 15-cm depth (Ap horizon) to favorable levels of 3 to 5 at Site 1 but at Site 2 they remained in the 12 to 15 range. For the other four tillage treatments (simulated normal tillage, simulated shallow plowing, chiselling and chiselling plus simulated shallow plowing), the nonamended subplots at both sites had undesirably high SAR values in the 16 to 23 range. There was a trend for gypsum to lower SAR values of the 0- to 15-cm depth in most cases to the 10 to 15 range and was usually more effective than lime. For the 15- to 30-cm depth (Bnt) there was a trend for gypsum, and to a lesser degree lime, to lower SAR values from the 15 to 38 range to the 14 to 28 range 4 yr after the amendments had been applied. There was a negative correlation [Formula: see text] between SAR and soil aggregates < 6 mm in diameter and a positive correlation [Formula: see text] between SAR and soil clods in the 25- to 76-mm size. There was also a negative correlation [Formula: see text] between SAR and mean weight-diameter (water stable aggregates). Simulated deep plowing at Site 1 produced higher yields of alfalfa and barley than the other four tillage treatments [Formula: see text]. Alfalfa yields were considerably lower at Site 2 than at Site 1, but again simulated deep plowing produced the highest of all the tillage treatments. However, due to cloddiness of the seedbed at Site 2 in the simulated deep-plowed plots, germination of barley was poor for years when the spring season was dry. The chiselling treatment produced the highest yields of barley at this site. Gypsum, and to a lesser extent lime, lowered the SAR of the seedbed and improved aggregation but after 4 yr the 18 t ha−1 rate had only started to ameliorate the Bnt at both sites. Key words: Solonetzic soils, sodium adsorption ratio, soil aggregation, soil cloddiness
OVERWINTER LOSSES OF NITROGEN-15 LABELLED UREA FERTILIZER
Authors: BOLE J. B. , GOULD W. D.
Published: March 2010

Field studies using 15N microplots were conducted to quantify the uptake and disappearance of fall- and spring-applied urea N on low organic matter, irrigated soils. Urea was mixed with the surface soil to maximize the potential for overwinter nitrification and subsequent losses of the fertilizer N. In three irrigated soils, losses of fall-applied urea averaged 24–31% compared with 11–21% of that applied at seeding. Barley took up 33–42% of spring-applied urea N but only 16–36% of fall-applied urea N. The lower uptake of fall-applied N apparently resulted from higher N losses rather than from the immobilization of fall-applied urea. Fall application resulted in lower soil reserves of residual fertilizer N after the growing season, as compared to spring application, in two of the three studies. Sixty percent of the fertilizer N recovered from the soil remained in the surface 15 cm. The application of 50 mm of water in the fall or 100 mm in the early spring, to intensify any effects of moisture, had a minimal effect on N losses or the distribution of N in the soil. This suggests that an individual rainfall event would not greatly affect the uptake or losses of fall-applied fertilizer on well-drained soil. The observed fertilizer losses, however, support practices such as concentrating fall-applied fertilizers in bands or the use of nitrification inhibitors. Key words: Denitrification, nitrogen, fertilizer, N balance, N losses, urea
CHANGES IN NITRATE CONCENTRATION OVER WINTER IN THREE SOUTHERN ONTARIO SOIL PROFILES
Authors: SHEPPARD S. C. , BATES T. E.
Published: March 2010

Our study consisted of three sites, continuously cropped with grain corn and fertilized annually with N rates ranging from 0 to 336 kg ha−1. Soil NO3-N was measured to 90 cm at least twice yearly over three cropping seasons. In Ontario’s semi-humid environment, soil nitrate (NO3-N) is usually completely lost from soil profiles over the winter months by leaching and denitrification. We found this to be generally true over 3 yr on a sandy loam and on a silt loam soil. However, on a clay loam soil in 2 of 3 yr NO3-N concentrations in the spring were almost as high as those of the previous fall. Key words: Nitrate, corn, continuous cropping, retention
TEST OF THE LECO CHN-600 DETERMINATOR FOR SOIL CARBON AND NITROGEN ANALYSIS
Authors: SHELDRICK B. H.
Published: March 2010

Soil carbon and nitrogen were determined by a LECO CHN-600 determinator; precision and rate of analysis by the new method were compared with those by two other methods. Precision of total carbon data as expressed by the range of standard deviations of seven values for each of 10 samples with carbon contents of 0.1–11% were: CHN-600, 0.01–0.13; LECO induction furnace 0.02–0.86; and wet oxidation 0.04–0.96 Standard deviations of nitrogen data by the CHN-600 ranged from < 0.01 to 0.02 for samples with total nitrogen of 0.01–0.95%. Rate of determination of carbon and nitrogen by the CHN-600 was more than double that of either of the other carbon methods combined with nitrogen by Kjeldahl. Key words: Soil, carbon, nitrogen, precision, rate of analysis
INFLUENCE OF PHOSPHATE IONS ON THE EXTRACTION OF ALUMINUM BY 8-HYDROXYQUINOLINE FROM OH-AL SUSPENSIONS
Authors: PASCALE G. DI , VIOLANTE A.
Published: March 2010

Aluminum was extracted from OH-Al-suspensions ([Al3+] = 6.4 × 10−4 mol L−1; OH/Al molar ratio = 1.0, 1.5, 2.2) aged 5 and 18 mo by 8-hydroxyquinoline into four different species: readily extractable (Alre), moderately ex tractable (Alme), slowly extractable (ALse) and nonextractable (Alne) aluminum. In all the systems, the percentages of Alre were the highest of the ultrafiltered hydrolytic products of Al, ranging from 68.1 to 21.1%, whereas the percentages of Alme and Alse were [Formula: see text]. The higher the OH/Al molar ratio and the longer the aging period of OH-Al-suspensions, the lower the percentages of Alre, Alme and Alse, and the higher the percentages of Alne (ranging from 13.3 to 71.1%). With addition of phosphate ions, increasing the P/Al molar ratio from 0.05 to 0.5 decreased Alre and increased Alne. Finally, it was ascertained that the ultrafiltered aluminum was not completely extracted by 8-hydroxyquinoline after 3 h. More aluminum was extracted from 3 to 48 h from the suspensions containing phosphate ions than from those without phosphate. Key words: Aluminum hydrolytic products, phosphate, aluminum extraction, 8-hydroxyquinoline
INFLUENCE OF THE SPATIAL DISTRIBUTION OF SAND CONTENT ON SAMPLING PATTERNS
Authors: O’HALLORAN I. P. , STEWART J. W. B. , KACHANOSKI R. G.
Published: March 2010

The spatial variability of sand content (0–15 cm) was examined on a crop rotation study site located on a Brown Chernozemic loam soil at Swift Current, Saskatchewan. The autocorrelation for surface sand content indicated a significant cyclic pattern, with a wavelength of approximately 56–65 m, which was considerably longer than the experimental plots (40 m). Since the sand content was not randomly distributed in space (and therefore all soil properties correlated to sand would also be nonrandomly distributed in space), an alternative sampling pattern had to be devised which would allow for an adequate measurement of the soil properties in each plot. Based on the autocorrelation function, a sampling interval of approximately 10 m was selected. The bootstrap method was used to compare a random versus a fixed interval-sampling pattern for these plots. Both patterns adequately estimated the mean of the population, but the random sampling pattern gave a greater amount of variation in the mean values. In addition, the random sampling pattern consistently underestimated the variance by as much as 30%. The fixed interval-sampling pattern gave a much better estimate of the variance (usually within 10%). The techniques used in this study would allow the development of sampling patterns to obtain unbiased estimates of soil properties, within experimental plots, which may not be randomly distributed in space and/or normally distributed. Key words: Soil variability, spatial distribution, sampling patterns, sand content
CROP UTILIZATION AND SOIL RETENTION OF NITROGEN FROM 15N-LABELLED UREA, CALCIUM NITRATE, and AMMONIUM SULPHATE IN SEVERAL MANITOBA SOILS
Authors: OBI A. OLU , HEDLIN R. A. , CHO C. M.
Published: March 2010

A growth chamber study was carried out to determine crop utilization of nitrogen added as 15N-labelled calcium nitrate or urea to eight Manitoba soils of diverse characteristics. Dry matter yield of wheat was significantly greater where calcium nitrate was used as a nitrogen source than when urea was the nitrogen source in Pine Ridge, Wellwood, and Granville soils. Residual nitrogen in the soil at the end of the experiment was greater where urea was used than where calcium nitrate was used. Total recovery of urea nitrogen generally exceeded recovery of nitrogen from calcium nitrate. In a laboratory study it was found that more of the nitrogen added as urea or ammonium sulphate was retained than when nitrogen added was as calcium nitrate. Rapid ammonium fixation from ammonium-yielding carriers occurred, especially in the Granville and Waitville soils. Ammonium fixation could be one reason for the higher utilization of nitrogen from nitrate than from ammonium sources. Key words: Nitrogen availability, ammonia-soil interaction
AVAILABILITY OF NITROGEN FROM THREE MANURES TO CORN IN THE FIELD
Authors: BEAUCHAMP E. G.
Published: March 2010

Three manures were compared with urea as sources of nitrogen for corn (Zea mays L.) on a different field site in each of 3 yr. The manures and their average [Formula: see text]–N:total N ratios were as follows: liquid poultry manure (LPM), 0.89; liquid dairy cattle manure (LCM), 0.53; and solid beef cattle manure (SBM), 0.09. The manures were applied at rates of 100, 200 and 300 kg total N ha−1. An additional LCM treatment of 600 kg total N ha−1 was also included. For comparison with the manures as N sources, urea was applied at rates of 50, 100 and 150 kg N ha−1. The yield response data were examined on the basis of a previously suggested model which predicted that all of the [Formula: see text]–N and part (e.g., 10–20%) of the organic N in manures are available for crop growth in the field. Regression analyses of paired yield data sets of urea and LCM or urea and LPM indicated that only 75–80% of the [Formula: see text]–N fraction applied in these manures was equivalent to urea-N. Thus, it was concluded that the model did not take into account net N immobilization and possibly N losses through denitrification following application. It was concluded also that N release from the organic N fraction of SBM differed substantially from that for the other manures. This conclusion was supported by greenhouse data which indicated that net N immobilization occurred for the first crop shortly after SBM was applied but this was followed by net N mineralization for a second crop as manure decomposition continued. Soil NO3− concentrations in mid-June generally increased with the urea, LPM and LCM sources of N at the higher rates of application in the field. Lower soil NO3− concentrations with SBM reflected the lower availability of N. Key words: Corn, manure N availability, Zea mays L.
EFFECTS OF HUMIC SUBSTANCES ON NITRATE UPTAKE AND ASSIMILATION IN BARLEY SEEDLINGS
Authors: ALBUZIO A. , FERRARI G. , NARDI S.
Published: March 2010

Barley seedlings (Hordeum vulgare L. ’Astrix’) were incubated with humic substances extracted with 0.1 M Na4P2O7 from a grassland soil and with their fractions obtained either by gel-permeation chromatography on Sephadex G100 or by dialysis. After incubation the seedlings were transferred into an assay medium, in order to evaluate the rate of nitrate uptake and the extractable activities of nitrate reductase (NR), glutamate dehydrogenase (GDH), and glutamine synthetase (GS). Nitrate uptake was inhibited for up to 4 h incubation with unfractioned humic extract (UH), while it was progressively stimulated after 4–16 h incubation. The maximum stimulation was obtained at 100 mg L−1 humus concentration. The above enzyme activities were stimulated by UH: NR to the same degree, GDH and GS to a lower degree than nitrate uptake. Sephadex fractions stimulated nitrate uptake to a level decreasing in the following sequence of apparent molecular weight: < 9000; > 100 000; 9000–100 000. None of the fractions affected significantly GDH and GS activities. The humic fraction of molecular weight > 9000 separated by dialysis, differently from the Sephadex fractions of the corresponding molecular size, was effective on the uptake and also on the enzyme steps of nitrate assimilation. Therefore, the regulatory properties of humic substances appeared to be dependent not only on their molecular size, but also on the reciprocal interactions of the different constituents, which were affected by the fractionation procedure. Key words: Humic fractions, nitrate uptake, barley seedlings
DETERMINATION OF VARIABILITY IN SOIL PHYSICAL PROPERTIES AND MICROBIAL BIOMASS UNDER CONTINUOUS DIRECT-PLANTED CORN
Authors: CARTER M. R. , WHITE R. P.
Published: March 2010

The spatial variability of soil strength, porosity, and microbial biomass was determined under 4-yr continuous direct-planted silage corn (Zea mays L.) on Prince Edward Island. All soil properties changed relative to the row position. Microbial biomass C and N were lower in the in-row compared to the between-row position. Positional and depth differences for soil bulk density and volume of macropores (EPD > 50 μm) were only evident at the soil surface (0–8 cm). Temporal and spatial variations in soil strength indicated the extent of the rooting potential within the soil profile, the depth to compacted soil layers, and the degree of soil structure regeneration during the winter period. Key words: Spatial variability, soil strength, soil porosity, microbial biomass, direct-planted corn, Zea mays L.
DETERMINING AMMONIUM OXALATE-EXTRACTABLE Si IN SOILS
Authors: WANG C. , SCHUPPLI P. A.
Published: March 2010

Determination of oxalate-extractable Si and Al is useful in assessing the degree of accumulation of allophane-like materials in Podzolic soils. Three procedures were tested for determining Si: manual spectrophotometry, automated spectrophotometry and atomic absorption. For concentrations of oxalate-extractable Si above 0.5 g kg−1, there was no significant difference among results by the three procedures. For lower concentrations of Si, results by atomic absorption were higher than those by the spectrophotometric procedures. Determination by Si by autoanalyzer is the preferred procedure as it is convenient, sensitive and reliable. Key words: Oxalate Si, Podzolic soil, autoanalyzer
DISPONIBILITÉ DU PHOSPHORE DANS LES SOLS NEUTRES ET CALCAIRES DU QUÉBEC EN RELATION AVEC LEURS CARACTÉRISTIQUES CHIMIQUES ET PHYSIQUES
Authors: TRAN T. SEN , GIROUX M.
Published: March 2010

Seven chemical methods (Bray-II, Bray-I, North Carolina DA-4, DA10, Mehlich II, Mehlich III and Olsen) and two anion exchange resins (F− and [Formula: see text] forms) were evaluated on 43 soils with pH varying from 6.4 to 7.88. A greenhouse experiment was carried out with ryegrass receiving two treatments (without P fertilization and 150 mg kg−1 soil) on these soils. The Olsen's method and the two anion resins used as reference ones were effectively the better correlated with P uptakes (r = 0.83**–0.87**) and relative yield (R2 = 69.3–70.2%). The Mehlich II, Mehlich III and to a lesser extent Bray-I methods showed good correlations with these reference methods (r = 0.77**–0.83**) and with plant P uptakes (r = 0.73**–0.79**) or relative yields (R2 = 48.9–55.1%). The Bray-II, DA-4 and DA-10 methods may dissolve some calcium phosphates such as apatites or tricalcium phosphate in some soils and thus overestimated their available P content. The P amounts extracted by these methods were less correlated with P uptakes (r = 0.57*–0.67**) or relative yields (R2 = 14.4–31.4%). On the other hand, the DA-4 extractability was diminished in soils containing more than 3% of carbonates. Although the Ca-P was the predominant form in these soils, the P fixation capacity (M) and maximum P buffer (Mb) capacity were mostly related with Al and Fe-oxalate contents. However, the low Mb values obtained from these soils indicated that the P concentration in soil solution is more favored with respect to adsorbed P. Organic matter and clay contents, pH (H2O), exchangeable Ca and carbonate contents had some effects on the extraction capability of some methods without affecting plant P uptakes. Key words: Available P, soil testing, anion exchange resins, soil properties, P fixation
THE DEVELOPMENT OF NITROGEN CYCLING IN SUBALPINE RECLAIMED MINE SITES IN SOUTHEASTERN BRITISH COLUMBIA
Authors: FYLES I. H. , McGILL W. B.
Published: March 2010

The development of a nitrogen cycle in three subalpine reclaimed grasslands (1, 4 and 8 yr old) was studied in the field by following the flow of 15N through soil and plant components for 2 yr after the addition of labelled fertilizer. Comparative data were collected from an adjacent undisturbed native grassland. Plant recovery of labelled N accounted for an average of 76% and 79% in the 8- and 4-yr-old sites, respectively, but in the 1-yr-old site it accounted for only 43%. The proportion of plant nitrogen which was derived from fertilizer declined from 33% in the 1-yr-old site to 14% in the 4- and 8-yr-old sites and was 12% in the grassland. This decline was attributed to dilution of labelled N by mineralization of unlabelled organic N that had accumulated in the system in previous years. The active organic N fraction in the soil of the 8-yr-old site was five times larger than in the 1-yr-old site, and 1/2 to 1/3 as large as in the grassland. Enrichment of the microbial biomass with 15N was 5–10 times greater in the 1-yr-old site than in any of the other study sites. The ratio of active N/litter is proposed as a control on stability of reclaimed systems, with the ratio increasing to a steady-state as systems develop. We have concluded that N redistribution and recycling processes developed within 8 yr at the sites examined. Although the active fraction recycled N under conditions of annual fertilization, it remained a net N sink with its growth driven by C inputs from plant biomass generated by fertilizer inputs. After fertilization was terminated, growth of the active fraction slowed substantially, it continued to recycle N, and maintained its own characteristic plant productivity. Key words: 15N, nitrogen cycling, coal mine reclamation, active fraction
CONTRIBUTION OF EXCHANGEABLE ALUMINUM TO CATION EXCHANGE CAPACITY AT LOW pH
Authors: DUQUETTE MARTIN , HENDERSHOT WILLIAM H.
Published: March 2010

The cation and anion exchange capacities (CEC and AEC) as functions of pH were measured for 12 soil samples from various parts of Quebec. In addition to the index cation Ca, Al was measured in the replacing solutions in order to evaluate the contribution of Al to pH-dependent CEC at low pH. Although all of the soils possessed some pH-dependent CEC, the soils with the steepest rise in CEC with pH were those with the largest accumulation of sesquioxides. The effective CEC, measured at the soil pH, ranged from 2.4 to 37.2 cmol(+) kg−1 while the CEC at pH 7 minus the CEC at pH3 varied from 4.4 to 39.9 cmol(+) kg−1. The maximum amount of exchangeable Al was found to correlate very highly with the amount of amorphous inorganic Al in the samples. The inclusion of exchangeable Al in the calculation did not significantly reduce the amount of pH-dependent CEC measured for the soils. Key words: Effective CEC, permanent charge, pH-dependent CEC
ÉTUDES DES SOURCES D'AZOTE ET DE PHOSPHORE ET DU TAUX DE FERTILISATION SUR LA PRODUCTION DU TABAC À CIGARE
Authors: LAMARRE MICHEL
Published: March 2010

A study was carried out over a 5-yr period on the influence of different forms of N and P on agronomic and chemical characteristics of cigar tobacco. Results showed that sulphur-coated urea significantly increased yield and gross return when compared with urea alone, but not when compared with ammonium nitrate or ammonium sulphate. Regular superphosphate (0–20–0) was shown to be superior to concentrated superphosphate (0–46–0) for yield, quality index and gross return. Key words: cigar tobacco, nitrogen, phosphorus
SOME ASPECTS OF QUATERNARY SOILS IN CANADA
Authors: VALENTINE K. W. G. , TARNOCAI C. , KIMPE C. R. DE , KING R. H. , DORMAAR J. F. , VREEKEN W. J. , HARRIS S. A.
Published: March 2010

This review describes some aspects of Canadian soils that are relevant to the Quaternary. It includes a description of the Quaternary Period in Canada, including a chronology of the major events that influenced soil formation, and the implication of the Quaternary to Canadian soils. The contribution of relict and buried paleosols to Quaternary stratigraphy and the reconstruction of paleoenvironments is then discussed, including some of the inherent problems. Pedologic evidence of environmental change in the southern Rocky Mountains, including tephrostratigraphy, is followed by a description, with numerous radiocarbon dates, of Holocene peat deposits. The review concludes with a discussion of weathering and saprolites in eastern Canada. Key words: Quaternary, Holocene, paleosols, stratigraphy, paleoenvironments, peat
EFFECTS OF NUTRIENT AVAILABILITY AND SUBSOIL BULK DENSITY ON CORN YIELD AND NUTRIENT ABSORPTION
Authors: MILLER M. H. , MITCHELL W. A. , STYPA M. , BARRY D. A.
Published: March 2010

A 4-yr study was conducted to determine the extent to which soil fertility and subsoil bulk density limit corn yields at the Elora Research Station. In one treatment, soil was replaced to a depth of 1 m with a highly fertilized soil:peat:perlite artificial medium (AM). Two other main treatments consisted of the natural soil with either a recommended fertility (RF) or a very high fertility (VHF) treatment. Plots were irrigated using a trickle system. Corn (Zea mays L.) yields on the artificial medium were the same as those on the VHF treatment in all 4 yr. This was unexpected because of a high subsoil bulk density (1.5 Mg m−3 in the Bm and 1.8 Mg m−3 in the Ck horizons). Grain dry matter yields on the VHF treatment were considerably higher than those on the RF treatment (7.8 compared to 5.3 t ha−1) and were higher than the average yield (6.1 t ha−1) on the best treatment in a previous long-term fertility experiment at Elora. The response appeared to be due to all three macronutrients. Some response to N and K was expected, but the response to P, which was a major portion of the total response, was unexpected. It is concluded that subsoil bulk density is not a significant limitation on this soil when adequate water and nutrients are provided. The marked response to phosphorus application above recommended rates may indicate a need to re-evaluate the fertility requirements of high-yielding corn hybrids. Key words: Soil bulk density, corn yield, nutrient absorption, phosphorus, fertility
EFFECTS OF SUBSOIL BULK DENSITY, NUTRIENT AVAILABILITY AND SOIL MOISTURE ON CORN ROOT GROWTH IN THE FIELD
Authors: STYPA M. , NUNEZ-BARRIOS A. , BARRY D. A. , MILLER M. H. , MITCHELL W. A.
Published: March 2010

In a 4-yr study, root growth in the upper 50 cm of a silt loam soil (Gleyed Melanic Brunisol) was equal to or greater than that in a low-density artificial medium (soil:peat:perlite) in spite of a high bulk density in the soil (1.5 Mg m−3 in the 15-to 45-cm depth). We suggest that, due to the natural structure of the Bm horizon, the resistance to root growth is much less than would be expected from bulk density or penetrometer resistance measurements. Marked increases in P and K fertility in the surface soil had only minor effects on either the total length or distribution of roots although the shoot growth was markedly increased. Neither total root length nor root distribution were altered by irrigation during 1981, the only year a moisture variable was included. During a 2-wk dry period in July, prior to anthesis, soil water potential on the nonirrigated plots decreased to −1.5 MPa in the upper 15 cm and to −0.5 MPa in the 15- to 30-cm layer. Leaf water potential, stomatal conductance and rate of growth during the period were lower on the nonirrigated treatment although final dry matter production was not. The results indicate that corn root growth and distribution in the field are not as sensitive to environmental factors as one would expect from short-term laboratory studies. Key words: Corn, root growth, soil bulk density, fertility, soil water
BIOLOGICAL PROPERTIES OF SOME PRINCE EDWARD ISLAND SOILS: RELATIONSHIP BETWEEN MICROBIAL BIOMASS NITROGEN AND MINERALIZABLE NITROGEN
Authors: CARTER M. R. , MACLEOD J. A.
Published: March 2010

The mineral N flush, a measure of microbial biomass N, and the N mineralization potential (No) were determined in eight representative agricultural soils (Humo-Ferric Podzols and Gray Luvisols) of Prince Edward Island. The acidic (pH 5.0–5.8) soils, varying in texture from loam to loamy sand had an organic C range of 0.75–2.74%. Both mineral N flush (4–38 μg N g−1 soil) and the percentage soil organic N in the mineral N flush (0.4–2.0%) were relatively low compared to other studies. This observation was related to the generally low pH range of these soils. Potentially mineralizable soil N (No) ranged from 44 to 247 μg N g−1 and accounted for 4.5–13.3% of the total soil organic N. The No was closely related to the mineral N flush (r2 = 0.94) but poorly related to percent organic matter (r2 = 0.26) or organic N (r2 = 0.38). The results indicate that for these soils of similar properties, with low levels of residual mineral N, the mineral N flush could be utilized as an indirect measure of the soil N mineralization potential. Key words: Biomass C, mineral N flush, N mineralization potential, Podzolic soil, Luvisolic soil
SULPHATE RELATIONSHIPS IN SOME CENTRAL ONTARIO FOREST SOILS
Authors: NEARY A. J. , MISTRY E. , VANDERSTAR L.
Published: March 2010

The [Formula: see text] status of sandy, podzolic soils from central Ontario was examined. Water-soluble [Formula: see text] was positively correlated with soil organic C concentrations but not with Fe and Al oxides (citrate-dithionite-bicarbonate minus pyrophosphate extractable Fe and Al). For adsorbed [Formula: see text] the reverse was true. Surface horizons were high in soluble [Formula: see text] and low in adsorbed [Formula: see text] whereas B horizons containing high levels of Fe and Al oxides contained large amounts of adsorbed [Formula: see text] and little soluble [Formula: see text]. Successive distilled water extractions of some samples indicated the removal of almost all soluble [Formula: see text] from surface horizons in one or two extractions. Sulphate, however, remained present in the B horizons after five extractions. The amount of soluble [Formula: see text] extracted was dependent on horizon type and amount of water used for extraction. This makes evident the importance of moisture status, residence time and hydrologic pathways in determining [Formula: see text] release from the soil, and demonstrates the need for in situ studies. Plastic Lake B horizons adsorbed added [Formula: see text] in the laboratory but it was not determined whether this is occurring in the field. Key words: Soluble [Formula: see text], adsorbed [Formula: see text], sulphate, iron oxide, aluminum oxide, podzol
TRANSPORTABILITY OF IODIDE IN SOME ORGANIC SOIL MATERIALS FROM THE PRECAMBRIAN SHIELD OF ONTARIO
Authors: KOCH J. T. , KAY B. D.
Published: March 2010

Knowledge of the transportability of the long-lived and potentially hazardous nuclide 129I in organic soils is important for evaluating the concept of safely disposing of radioactive fuel waste from Canadian nuclear power plants. The current concept for the disposal of nuclear fuel waste in Canada involves its emplacement in a vault mined 500–1000 m deep in a stable plutonic rock formation in the Canadian Shield. Degradation over time of components of the vault could lead to the entry of 129I to organic soils from contaminated groundwater. Twelve samples from nine organic soils, widely different in degree of humification and in parent vegetation, were collected from the Precambrian Shield of Ontario. Batch reaction techniques were used to measure the kinetics of iodide loss from solution in the presence of the organic soil materials. All soil materials exhibited an initial constant rate of iodide loss from solution (zero-order kinetics). The rate constants for iodide loss for the different soil materials ranged from 1.44 to 36.0 mg iodide per kilogram soil per day. The natural I content for the organic soil samples was positively correlated to the measured rate constant. It is concluded that the rate constant for iodide, as measured in the laboratory, is related to the processes that operate in the field to immobilize I under natural conditions, and that a zero-order kinetic model is appropriate for describing the loss of iodide from the solution phase in an organic soil. Key words: Organic soils, iodide-129, groundwater, transport kinetics, immobilization
A METHODOLOGY FOR MAPPING AND MONITORING CROPLAND SOIL EROSION
Authors: CIHLAR JOSEF
Published: March 2010

A methodology is described for mapping and monitoring the erosion of soil by water, using remote sensing techniques and the universal soil loss equation as the primary tools. Four aspects are covered: mapping baseline sheet and rill erosion, monitoring actual rill and gully erosion, estimating changes in potential sheet and rill erosion, and determining long-term trends. A successful field evaluation of the methodology was undertaken in a potato-growing area of New Brunswick. The implementation of the procedure using state-of-the-art microcomputer and satellite remote sensing technology is proposed. Key words: Soil erosion, remote sensing, geographic information systems
EFFECT OF CROP ROTATIONS AND FERTILIZERS ON MOISTURE CONSERVED AND MOISTURE USE BY SPRING WHEAT IN SOUTHWESTERN SASKATCHEWAN
Authors: CAMPBELL C. A. , ZENTNER R. P. , STEPPUHN H.
Published: March 2010

The effects of crop rotation and fertilization on moisture conserved and moisture use efficiency (MUE) were assessed on a loam soil in the Brown soil zone of southwestern Saskatchewan over the period 1967–1984. Six spring wheat rotations were examined that were either fertilized at soil test recommended rates of N and P, or N or P was withheld according to rotation specifications. MUE in this study was calculated as grain yield divided by sum of 1 May to 31 Aug. precipitation plus soil moisture used between seeding and harvest. In the first fall after harvest 8–11 % of the precipitation received was stored in soil in all rotations. During the first winter 3–5 times as much moisture was stored as was stored in the fall; compared to continuous wheat receiving only P, continuous wheat fertilized with N and P increased moisture storage by 12 mm due to a larger amount of crop residues left in the field. In the first 9 mo of summer-fallow, 33% of the precipitation was stored, but over the entire 21-mo fallow period only 18% was stored. At seeding, fallow-seeded crops receiving P annually had 43 mm more moisture in the 120-cm profile than stubble-seeded wheat that received N and P. Failure to apply P to wheat grown on fallow in the F-W-W rotations reduced spring soil moisture at seeding by about 8 mm. Wheat seeded on fallow retained more moisture in soil compared to wheat seeded on stubble until the shot blade stage, but at harvest and fall sampling there was no difference. At harvest there was no available moisture in the top 90 cm of soil. Wheat made greater use of stored soil moisture in dry years than in wet. Wheat grown on fallow that received P used 102 mm of soil moisture per year; wheat on fallow receiving no P used 93 mm; wheat on stubble receiving N and P used 61 mm and continuous wheat receiving no N used 50 mm. The 18-yr average MUE was as high as 6.9 kg ha−1 mm−1 for wheat on fallow that received P and as low as 5.1 kg ha−1 mm−1 for continuous wheat receiving no N. These values were much greater than those reported 30–40 yr ago for this area and reflect improved crop management and crop varieties now used. The improvement in MUE due to fertilizer was greater in later years due to the cumulative effect of fertilizer on soil quality, crop production and crop residues which enhanced moisture available for use. When efficiency was based on the precipitation received from harvest to harvest continuous wheat receiving N and P had the highest efficiency (3.75 kg ha−1 mm−1) and the 2-yr fallow-wheat rotation the lowest (2.60 kg ha−1 mm−1). Key words: Water use efficiency, WUE, nitrogen, phosphorus and moisture use, summerfallow and moisture conservation
INFLUENCE OF CROPPING HISTORY AND CHEMICAL TREATMENTS ON THE WATER-STABLE AGGREGATION OF A SILT LOAM SOIL
Authors: BALDOCK J. A. , KAY B. D.
Published: March 2010

Changes in cropping practices can alter soil structural characteristics. The purpose of this study was to assess the extent and rate at which bromegrass (Bromus inermis Leyss) and continuous grain-corn (Zea mays L.) influence soil aggregation and various soil binding agents. Five cropping treatments ranging from 15 yr of continuous grain-corn to 15 yr of continuous bromegrass production were investigated. Soil aggregation and the nature of soil binding agents were determined by measuring the water-stable aggregate size distribution subsequent to the application of six chemical pretreatments — control, distilled water, 0.08 M sodium azide, 0.08 M sodium chloride, 0.08 M sodium periodate, and 0.02 M sodium pyrophosphate. A simple power function was used to describe the relationship between the cumulative percentage by weight of water-stable aggregates and aggregate diameter. The exponent in the power function provided a measure of the influence of cropping treatment and chemical pretreatment across the whole range of aggregate sizes. The size and stability of aggregates increased with increasing domination of bromegrass in the cropping history. Materials resistant to soaking in water contributed to the increased stability under bromegrass. Materials sensitive to periodate and pyrophosphate anions contributed to the stabilization of aggregates from all cropping treatments. However, these materials did not appear to account for the differences in structural stability observed across cropping treatments. The rate of structural deterioration induced by grain-corn production under conventional tillage appeared to be faster than the rate of structural enhancement promoted by bromegrass production. Key words: Polysaccharides, periodates, pyrophosphate, corn, bromegrass, aggregate stability
ESTIMATING SOIL NET NITROGEN MINERALIZATION AS AFFECTED BY TILLAGE AND SOIL DRAINAGE DUE TO TOPOGRAPHIC POSITION
Authors: RICE C. W. , GROVE J. H. , SMITH M. S.
Published: March 2010

The influence of tillage on net nitrogen mineralization out of sod for two toposequences was estimated by several different methods. A field procedure utilizing small rain shelters to prevent leaching was employed to measure N mineralized in no-tillage (NT) and plowed (CT) treatments for six soils. Potentially mineralizable N and autoclavable N were also determined. An intact soil core procedure was developed to measure N mineralization. With the field procedure, mineralized N was generally greater in the well-drained soils but decreased with decreasing drainage. There was a highly significant interaction between soil type and tillage with greater amounts of N mineralized in the plowed well-drained soils but less in the poorly drained soils when compared to the corresponding no-tillage treatment. The standard laboratory estimates were able to predict differences between soils but did not predict the tillage effect. The development of a laboratory intact core procedure allowed for simulation of tillage effects and was correlated to the field estimates (r = 0.76). More importantly, the tillage ratios for mineralized N (NT:CT), which varied from 1.38 to 0.43, were reasonably correlated (r = 0.73) between the field and intact core procedures. Key words: Mineralized N methods, no-tillage, moldboard plow tillage, intact cores
COMPARAISON DE DIFFÉRENTES MÉTHODES D'ANALYSE DE L'AZOTE DU SOL EN RELATION AVEC SA DISPONIBILITÉ POUR LES PLANTES
Authors: GIROUX M. , TRAN T. SEN
Published: March 2010

The objective of this study was to compare several methods of estimating the availability of soil nitrogen to plants. Total soil N, organic matter content, mineralized N during a 2 wk incubation at 35 °C, organic N in 6 N HC1, 0.01 M NaHCO3 and 1 N KCl extracts, and finally mineral N extracted by 2 N KCl were evaluated and contrasted with N uptake by sugar beets cultivated on 19 soils in a greenhouse experiment. The relative yield or plant N uptake gave the highest correlation coefficients when both mineral and organic N fractions in soil extract were considered. The incubation methods gave the best correlation coefficient with relative yield (R2 = 0.85**). N contents in NaHCO3 extract were more correlated with relative yield or N uptake than total N, organic matter contents or N extracted by 6 N HCl or 1 N KCl. The UV absorbance values obtained at 205 nm with 0.01 M NaHCO3 extract were also well correlated with relative yield (R2 = 0.78**) and plant N uptake (R2 = 0.66**). At this wavelength, as well as at 220 nm, the absorbance was affected by mineral and organic N contents in the extract. However, at 260 nm, the UV absorbance was only related to organic N in the extract; consequently these absorbance values were less correlated with relative yield (R2 = 0.49**) or N uptake (R2 = 0.27*). Furthermore, the absorbance measured at 205 nm was too sensitive to NO3-N and organic N concentration and this relationship was not linear in the high-N concentration range. The UV absorbance at 220 nm in the 0.01M NaHCO3 extract seemed to be a promising method to evaluate the availability of soil N. Key words: Soil nitrogen, incubation, ultraviolet absorbance, hydrolyzable nitrogen
THE CATALYTIC ROLE OF BIRNESSITE IN THE TRANSFORMATION OF IRON
Authors: KRISHNAMURTI G. S. R. , HUANG P. M.
Published: March 2010

The influence of birnessite (δ-MnO2) on the precipitation products of iron was studied, in the FeCl2-NH4OH system at different Mn/Fe molar ratios (0, 0.01, 0.1 and 1.0) and in the acidic pH (4.0, 5.0 and 6.0) range, by X-ray, TEM, IR and chemical analyses. The precipitation products formed at pH 5.0 and 6.0 were found to be lepidocrocite (γ-FeOOH) in the absence of birnessite. Birnessite promoted increased precipitation of Fe oxide; the oxidation of Fe(II) by MnO2 was thermodynamically feasible and was confirmed by the presence of Mn(II) in the solution by ESR data. Birnessite also influenced the crystallization processes of hydrolytic products of Fe which range from lepidocrocite through goethite (α-FeOOH), akaganeite (β-FeOOH), to X-ray noncrystalline Fe oxides. The noncrystalline Fe oxides formed at a Mn/Fe molar ratio of 1.0 were characterized by infrared absorption maxima at 1400 and 750 cm−1. Key words: Birnessite, Fe(II) oxidation, ESR, lepidocrocite, akaganeite, noncrystalline oxide