bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF CROPPING SYSTEM ON STRUCTURE OF BROOKSTON CLAY LOAM IN LONG-TERM EXPERIMENTAL PLOTS AT WOODSLEE, ONTARIO
Authors: McKEAGUE J. A. , FOX C. A. , STONE J. A. , PROTZ R.
Published: March 2010

Macro- and microstructure were described and water desorption characteristics were measured for a Brookston clay loam soil under different cropping systems. The Ap horizon of the long-term corn (Zea mays L.) plots differed markedly from those of a bluegrass (Poa pratensis L.) plot and a never-cultivated plot as follows: massive as opposed to strongly structured, macroporosity (pore width > 60 μm) ≤ 6% as opposed to more than 10%, isolated pores as opposed to interconnected pores, bulk density 1.4–1.5 Mg m−3 as opposed to 1.0–1.3 Mg m−3. The Ap horizon of the rotation plots, oats (Avena sativa L.), alfalfa (Medicago sativa L.), alfalfa, corn, differed from those of the continuous corn plots in having many more biopores larger than 0.5 mm in diameter (≥ 0.2% relative to ≤ 0.02%). Below a depth of 30 cm comparable horizons of soils from all plots were similar in structure, bulk density and water characteristic curves. Key words: Porosity, biopores, compaction, macromorphology, image analysis
PHYSICAL FACTORS INVOLVED IN THE FORMATION OF SOIL SHEATHS ON CORN SEEDLING ROOTS
Authors: FYSON A. , OAKS A.
Published: March 2010

A layer of soil (soil sheath) that is resistant to removal by shaking develops on corn seedling roots under a wide variety of environmental conditions. Low temperature (15 °C) and high soil moisture content (100% field capacity) promote the formation of the most substantial sheaths (> 11 mg of soil (dry weight) cm−1 root) in an Elora alfalfa soil. A diversity of corn genotypes and a teosinte form sheaths of comparable specific mass whereas much less soil adheres to pea and soybean roots in this soil. Cultivation history has a considerable influence on sheath mass. For example, at Elora, a soil under alfalfa for several seasons promotes sheaths of higher specific mass (9.9 ± 0.5 mg cm−1 root) than a continuous corn soil (7.1 ± 0.6 mg cm−1 root). Seeds inoculated with a fluorescent pseudomonad developed significantly more substantial sheaths in a 7-irradiated soil (11.2 ± 0.9 mg cm−1 root) than uninoculated, surface sterilized seeds (7.1 ± 0.6 mg cm−1 root). These observations suggest that a variety of factors influence the extent of sheath development. Key words: Soil sheath, temperature, soil moisture, soil type, fluorescent pseudomonads, corn
OXIDATION OF ELEMENTAL SULFUR UNDER FIELD CONDITIONS IN CENTRAL SASKATCHEWAN
Authors: JANZEN H. H. , BETTANY J. R.
Published: March 2010

A field study was conducted at 4 sites in central Saskatchewan to examine the oxidation rate of elemental S and its influence on soil pH. Finely divided S (approximately 7-μm diameter) was applied at a rate of 200 kg ha−1 to soil cores in aluminum cylinders. Three entire cores from each site were removed and analyzed for sulfate content and soil pH four times during a 16-mo period. All four soils exhibited significant oxidative activity. Twenty-three to forty-five percent of applied S was recovered as sulfate 10 wk after application. Sulfate concentrations recovered in the soil profiles declined after approximately 1 yr, partly due to leaching losses. Fertilizer-derived sulfate was most persistent in soils of finer texture. In the coarse-textured soils, most of the fertilizer-derived sulfate was apparently leached from the soil profile by the end of the 16-mo period. Soil pH was marginally reduced by oxidation following the application of elemental S but differences were no longer statistically significant at the last sampling time. Field incubation with elemental S substantially enhanced subsequent oxidative activity in three of the soils, suggesting that an initial application of elemental S fertilizer would enhance the effectiveness of subsequent applications. Substantial oxidation activity occurs in Saskatchewan soils even under the less than ideal conditions prevalent in this climatic region. It was concluded that elemental S in a finely divided form has strong potential as an effective fertilizer S source if appropriate fertilization strategies are adopted to maximize oxidation rate or compensate for delays in plant-available S release. Key words: Elemental S, pH, leaching, sulfate, immobilization
A SOIL SAMPLING PROCEDURE FOR MICROMORPHOLOGICAL STUDIES
Authors: WIRES K. C. , SHELDRICK B. H.
Published: March 2010

An inexpensive, lightweight adjustable hydraulic sampling system is described for obtaining "undisturbed" Kubiena box samples, in relatively stone-free mineral soil, for thin-section preparation. Key words: Hydraulic sampling, undisturbed soil samples, thin section
A COMPARISON OF MEASURED AND MODELLED SOIL WATER RETENTION DATA
Authors: JONG R. DE , MCKEAGUE J. A.
Published: March 2010

Soil water retention data, predicted from texture, organic carbon content and bulk densities, were compared to measured values. Although significant correlations were obtained, the differences between predicted and measured water contents were large, especially at high potentials, and suggest that extreme caution must be exercised in employing the models under conditions other than those for which they were developed. Key words: Soil water retention, modelling, texture
EFFECTS OF FOLIAR SPRAYS OF BORON APPLIED AT DIFFERENT STAGES OF GROWTH ON INCIDENCE OF BROWN-HEART IN RUTABAGAS
Authors: CUTCLIFFE J. A. , GUPTA UMESH C.
Published: March 2010

Two foliar applications of B at the rate of 1 kg ha−1 at 30 d and repeated at 42–45 d after seeding or a single preplant broadcast application of 2 kg B ha−1 provided excellent control of brown-heart in rutabagas (Brassica napobrassica Mill.). Similarly, two-application treatments initiated 40 d after seeding or later failed to prevent brown-heart at some locations. Root yields were slightly decreased by the two foliar sprays of B applied at five different stages of growth and by the single preplant soil application of B. Key words: Foliar treatments, boron, brown-heart, rutabaga
THE USE OF ISOSBESTIC POINTS IN THE FLUORESCENCE EXCITATION SPECTRUM OF HUMIC ACID TO CALCULATE THE DISSOCIATION CONSTANT
Authors: GOLDBERG MARVIN C. , CUNNINGHAM KIRKWOOD M. , WEINER EUGENE R.
Published: March 2010

Isosbestic points noted in the fluorescence excitation spectrum of humic acids, when taken as a function of pH, are sufficient information to treat the spectrum as the resultant of two and only two components absorbing in that spectral region. Equations are derived to calculate the concentrations of the absorbing species and the ionization constant of the species is determined. The second ionization constant of a humic acid extracted from the Ah horizon of the Beaverhills soil in central Alberta Canada was calculated to be 3.1 × 10−1. Key words: Humic acid, isosbestic point, fluorescence, excitation, ionization constant, light absorbing species
PHOSPHORUS TRANSFORMATIONS IN A SOIL CHRONOSEQUENCE, VANCOUVER ISLAND, BRITISH COLUMBIA
Authors: SINGLETON G. A. , LAVKULICH L. M.
Published: March 2010

Phosphorus fractionation and analyses for free oxides of Fe, Al and Si were carried out on depth interval samples taken from a sandy soil chronosequence on the west coast of Vancouver Island, British Columbia. The seven profiles sampled ranged in age from 127 yr at Site 1 to 550 yr at Site 7. Calcium-bound phosphate (PCa) decreased in the 0- to 5-cm depth interval samples from 105 mg kg−1 at Site 1 to 2 mg kg−1 at Site 7 and similar but less-pronounced decreases were noted for lower depths. Profile averages of PCa exhibited a linear function with time, whereas exponential trends were noted for the surface 10-cm samples. Key words: Phosphorus fractionation, soil chronosequence, chronofunctions, soil phosphorus
A SOIL CHRONOSEQUENCE ON BEACH SANDS, VANCOUVER ISLAND, BRITISH COLUMBIA
Authors: SINGLETON G. A. , LAVKULICH L. M.
Published: March 2010

A soil chronosequence near Cox Bay, on the west coast of Vancouver Island, British Columbia was investigated. Soils in the sequence have developed on sandy beach deposits, which are advancing toward the ocean at a rate of 0.26 m per year. Dendrochronology and geomorphology established surface ages ranging from 127 to 550 yr for seven selected pedons across these deposits. With soil age, there was progressive deepening and differentiation of genetic horizons, resulting in soil classification that ranged from an Orthic Dystric Brunisol at the youngest site (site 1) to an Orthic Humo Ferric Podzol at the oldest site (site 7). Organic matter increased from a maximum value for mineral horizons of 1.1% in the Bm of site 1 to 4.7% in the Ae of site 7. Oxalate-extractable Al in the uppermost B horizons of the soils increased from 0.12% at site 1 to 0.30% at site 6. Available Mg and K from the lowermost horizons sampled decreased from 35 and 25 mg kg−1 to 4 and 5 mg kg−1, respectively, when moving from sites 1 to 6. Accumulations of organic matter, Fe and Al, and losses of available Mg were plotted against soil age and yielded chronofunctions with exponential solutions. Key words: Soil chronosequence, soil genesis, Podzol development, chronofunctions
EFFECT OF WHEAT STRAW INCORPORATION ON DENITRIFICATION OF N UNDER ANAEROBIC AND AEROBIC CONDITIONS
Authors: AULAKH M. S. , RENNIE D. A.
Published: March 2010

The effects of wheat straw incorporation on denitrification, immobilization of N, and C mineralization were investigated at H2O contents of 60, 90 and 120% saturation. Incorporation of increasing levels of straw consistently increased the rate of denitrification for the first 4–8 d, followed by negligible N losses thereafter. In a total period of 96 d, the addition of 1.0% straw increased N losses from 2.5 to 10.1, and from 61.6 to 83.9 μg g−1 in the 60 and 120% water saturation treatments, respectively. The pattern of CO2-C evolved was practically identical to that of the denitrification rate for the initial period when sufficient [Formula: see text] was present. This study has confirmed that in flooded soils, high rates of denitrification will persist only when C is supplied by native or applied organic C sources, provided adequate [Formula: see text] is present. When [Formula: see text] was low, denitrification rates rapidly decreased, even with a sufficient supply of C. Immobilization of fertilizer N (50 μg N g−1 as K15NO3) was very rapid. Around 90% of the total immobilization of applied N occurred within 4 d. Incorporation of 1.0% straw increased the immobilization of fertilizer N from 8.4 to 42.8, and from 1.0 to 7.6% in the 60 and 120% water-saturated treatments, respectively. Remineralization of recently immobilized fertilizer N was observed after 32 d in the 60% saturation treatments only. Key words: Denitrification, wheat straw, mineralization of N
THE EFFECT OF Ca AND Mg CONCENTRATIONS IN NUTRIENT SOLUTION ON THE DRY MATTER YIELD AND Ca, Mg AND K CONTENT OF BARLEY (Hordeum vulgare L.)
Authors: GRANT C. A. , RACZ G. J.
Published: March 2010

Dry matter production by barley grown in nutrient solution culture was reduced by concentrations of Ca or Mg greater than 8 mmol L−1. Johnston barley was somewhat more sensitive to high levels of Ca and Mg than Bonanza. High concentrations of Ca or Mg did not inhibit uptake of K by the plant. Therefore, the reduction in barley growth was directly caused by excessive levels of Ca and Mg, and not due to a K deficiency induced by excess Ca or Mg. Key words: Calcium, magnesium, potassium, nutrient solution, barley, Hordeum vulgare
POTASSIUM STATUS OF IRRIGATED BROWN CHERNOZEMIC SOILS OF SOUTHERN ALBERTA
Authors: MaCKAY D. C. , CAREFOOT J. M.
Published: March 2010

A series of 10 field experiments conducted over a 4-yr period (1973–1976) on three of the most important Brown Chernozemic soils in the irrigated area of southern Alberta gave no significant yield responses to applied K (at rates of 0, 50, 100 and 150 kg ha −1 in 1973 and 0, 127, 254 and 508 kg ha−1 in the other years), using potato (Solanum tuberosum L.) as the test crop. The experiments included several cultivars, a variety of growing conditions, and diverse cropping histories. In addition, the K concentration of uppermost mature leaf blades obtained at the 10%-bloom stage were only slightly affected by K treatments, except in 1 yr (1975). The increased K uptake in 1975 was related to greater precipitation before irrigation was applied (66, 99 and 94 mm, respectively) during April, May and June in comparison with the long-term average of 32, 54 and 76 mm. The effects of early-season soil moisture stress were partially confirmed in a controlled environment (CE) experiment in which maintenance of soil water potentials between −30 and −20 kPa throughout the season caused greater uptake of added K in comparison with soil moisture stress in the 0–15 cm zone prior to the 10%-bloom stage. Yields of tubers were depressed with the stressed treatment, but there was no yield response to added K. Leaf analyses from the field experiments indicate that the critical K level of 43 g kg−1, which was established earlier for the Russet Burbank cultivar growing on Podzol soils is too high for irrigated Chernozemic soils, and that 30 g kg−1 would be a more valid tentative value. In a second CE experiment, designed to quantify the fate of applied K during intensive cropping, no yield responses to K applications were obtained with alfalfa on a coarse-textured Cavendish sandy loam during a 2-yr period. With no applied K, crop uptake reduced exchangeable K levels throughout the entire profile (66 cm) by about 20%. Thirty percent of the K removed by the crop originated from nonexchangeable soil K. With the highest K rate (450 kg ha−1 applied twice), 50% could be attributed to plant uptake, 15% to increased exchangeable K, and 35% to fixation in the nonexchangeable form. It is concluded that response to applied K on irrigated Brown and Dark Brown Chernozemic soils of southern Alberta is unlikely, even with intensive cropping, for some time in the future. A practical strategy for producers could be to apply moderate rates of K as a conservation measure when economic conditions are favorable and to rely on soil reserves in times of financial pressures. Key words: K-release, K-fixation, leaf analysis, fertilizer K requirements, soil water stress, K deficiency
AMELIORATION OF A SOLONETZIC SOIL BY SUBSOILING AND LIMING
Authors: WETTER L. G. , WEBSTER G. R. , LICKACZ J.
Published: March 2010

The effect of subsoiling and liming on a Dark Brown Solodized Solonetz was investigated by measuring changes in physicochemical status, root penetration, soil moisture status, and crop yields. Major differences were due to subsoiling. The pH of the Ap was increased from 5.7 to 7.0 following liming but to greater than 8.0 following subsoiling. Subsoiling elevated calcium salts from depth thus improving subsurface soil structure; SAR values of the Bnt horizon decreased from approximately 12 to less than 7; moisture status and root penetration were increased at depth. Average yearly yield of wheat was increased by 0.9 Mg ha−1 following subsoiling. The addition of lime in combination with subsoiling did not improve physicochemical properties, moisture status, or crop yields as compared to subsoiling alone. Subsoiling increased the clay content of the Ap from 16 to 27%, this elevation of clay increased the crust strength of the Ap horizon and hence the potential for surface crusting. Key words: Solonetzic, amelioration, subsoiling, lime
IN SITU NUTRIENT EXTRACTION BY RESIN FROM FORESTED, CLEAR-CUT AND SITE-PREPARED SOIL
Authors: KRAUSE H. H. , RAMLAL D.
Published: March 2010

Anion and cation resins were tested as sinks for nutrient ions under variable forest soil conditions. The resins, contained in nylon bags, were placed for periods of 4 wk below the forest floor of a softwood stand, and at approximately 7.5 cm depth on an adjacent clearcut with two different types of site preparation for tree planting. The soil was an Orthic Humo-ferric Podzol. Ion sorption below the forest floor, especially the sorption of ammonium, nitrate and phosphate, was strongly increased after clear-cutting of the forest. Sorption rates were generally lower in the mineral soil than immediately below the forest floor, except for nitrate and sulphate. Mixing of forest floor materials and fine logging debris into the mineral surface horizons generally increased resin sorption if compared to sorption in soil from which the forest floor had been removed. Resin sorption also revealed strong seasonal effects which may have been caused by changes in soil temperature and moisture. Key words: Ion exchange resin, forest soil fertility, seasonal nutrient fluctuation, site preparation
EFFECT OF CROP ROTATION AND FERTILIZATION ON THE QUANTITATIVE RELATIONSHIP BETWEEN SPRING WHEAT YIELD AND MOISTURE USE IN SOUTHWESTERN SASKATCHEWAN
Authors: CAMPBELL C. A. , ZENTNER R. P. , JOHNSON P. J.
Published: March 2010

The effects of crop rotation and fertilization on the quantitative relationship between spring wheat (Triticum aestivum L.) yields (y), available spring soil moisture (AvSpSM), and growing season precipitation (GSP) were determined from an experiment conducted on a loam soil in the Brown soil zone of southwestern Saskatchewan for the period 1967–1984. Moisture used (MU) was defined as[Formula: see text]and AvSpSM as volumetric moisture content at time of planting minus the lowest soil moisture measured at harvest. For discussion of moisture use characteristics GSP was defined as precipitation received from 1 May to 31 Aug.; for predictive equations GSP was more effective if GSP was taken as 1 May–31 July. When the 18-yr data were analyzed, the relation of y to MU was curvilinear. If data for 1 or 2 yr (1970 and 1983) with skewed distribution of GSP were omitted, the relationship between y (kg ha−1) and MU (mm) for well-fertilized fallow- and stubble-seeded wheat combined was[Formula: see text](where GSP = 1 May to 31 July). This equation performed well when it was used to estimate yields of fallow- and stubble-seeded wheat in 1985 and 1986. Stubble-seeded wheat required 68 mm of moisture to produce the first kilogram per hectare of grain; fallow-seeded wheat required about 46 mm. There was no effect of fertilizer on these lower threshold values, but the yield increase per millimetre of MU tended to be greater for the better fertilized rotations. The main difference in our y vs. MU relationships compared to those reported for the period 1925–1950 was that the lower threshold level of MU for grain production decreased from about 140 mm to the values cited above; this has resulted in substantially greater moisture use efficiency in recent years likely due to better, more timely crop management and the improved cereal varieties now used. When y was related to AvSpSM and GSP (1 May to 31 July) analyzed as separate variables, the relationship was only improved in terms of coefficient of determination (R2) value when a quadratic model was used. However, the latter did not predict the 1985 and 1986 yields as well as the y vs. MU relationship did. For fallow-seeded wheat, the relative effect of GSP on yield variability was about 5.4 times as great as that of AvSpSM; for stubble-seeded wheat it was only 1.5 times as great. GSP was equally important in affecting yields of wheat grown on fallow or stubble. The grain-filling period was confirmed as the most important for the occurrence of precipitation for both fallow- and stubble-seeded wheat, but precipitation at or near seeding time was almost as important for stubble-seeded wheat since this ensures the establishment of an adequate plant stand. Key words: Available moisture, growing season precipitation, timeliness of precipitation, regression analysis
EFFECT OF FOREST HARVEST ON DECOMPOSITION AND COLONIZATION OF MAPLE LEAF LITTER BY SOIL MICROARTHROPODS
Authors: BIRD G.A. , CHATARPAUL L.
Published: March 2010

The effect of whole-tree and conventional forest harvest on sugar maple leaf litter decomposition and the colonization of litter bags by soil microarthropods was investigated in a mixed conifer/hardwood forest on the Canadian Shield for 2 yr, beginning 17 mo after forest harvesting. Decomposition of leaves in litter bags was significantly greater (P < 0.05) on harvested plots than on the uncut plot (U), and was greater on the whole-tree harvest plot (W) than on the conventionally harvested plot (C). The increase in nitrogen (N) concentration of the litter over the 2-yr study was greater (P < 0.05) on the C than on the other plots and was in the order C > W > U. Colonization of leaf litter by soil microarthropods was greater (P < 0.05) on the U than on harvested plots, and was greater (P < 0.05) on the C than on the W plot. Thus, soil microarthropods did not appear to be responsible for the faster decomposition on harvested plots compared to the uncut plot, nor were differences in soil temperatures or moisture content among plots responsible for the faster rates of decay. More rapid decay on harvested plots suggests that harvesting increased the availability of nutrients contained in the forest floor. This may result in a loss of both nutrients and long-term productivity, especially with whole-tree harvesting, unless mechanisms are in place to conserve nutrients. Key words: Decomposition, soil microarthropods, whole-tree harvest, soil nitrogen, nutrient cycling, mineralization
WITHIN-PEDON VARIABILITY OF TRACE METALS IN SOUTHERN ONTARIO
Authors: WALL G. J. , MARSH M.
Published: March 2010

Replicate soil samples (three to six) from the surface (A), subsurface (B) and parent material (C) horizons of agricultural soils were collected from 10 pedons to measure within-pedon variability of nine elements (Cu, Zn, Mn, Sr, Co, Ni, Pb, Li, Cr). Elemental variability was examined in relation to the mode of deposition of the soil parent material, soil horizonation and soil drainage. Within-pedon variability as measured by the coefficient of variation (CV) ranges from low (CV < 10%) for Sr, Co, Li to intermediate (CV 10–20%) for Ni, Mn, Pb, Cr to high (CV > 20%) for Cu, Zn. Within-pedon variability of six (Cu, Sr, Co, Ni, Pb, Li) of the nine elements studied displayed no significant differences in variance due to horizon, drainage or mode of deposition. The number of replicate samples required for statistically reliable evaluation of a pedon at given confidence limits was determined for the elements studied. The number of samples required to estimate mean elemental concentrations (± 10%) ranged from 1 to 23. The study results emphasize the need for basing the design of field sampling procedures on existing knowledge of the relevant soil property within the context of the specific purpose of the study. Key words: Trace metal, variability, within-pedon
INORGANIC NITROGEN LEVELS AND NITRIFICATION POTENTIAL IN LOWBUSH BLUEBERRY SOILS
Authors: EATON LEONARD J. , PATRIQUIN DAVID G.
Published: March 2010

Soil ammonium and nitrate in the top 15 cm of soil were monitored after application of ammonium nitrate and ammonium sulfate to plots at 14 PF (previously fertilized) and 12 NF (never fertilized) lowbush blueberry (Vaccinium angustifolium Ait.) stands representing a range of soil types and management histories. Overall, nitrate values in unfertilized and ammonium sulfate plots were higher at PF than at NF sites, suggesting greater nitrification at PF sites. In laboratory incubation studies, nitrification proceeded immediately in soil from a PF site, but only after a 4-wk lag in that from an adjacent NF site. Nitrification rates were low compared to that in a garden soil (pH 6.6). N-Serve inhibited nitrification in both soils. In ammonium nitrate plots, "excess" N values (N values in fertilized plots minus values in unfertilized plots) were higher for PF than for NF sites, suggesting greater immobilization, plant uptake or loss of N at NF sites. There was no evidence, in laboratory studies, of immobilization of added N by soil from either type of site. Rhizome N concentration increased significantly in response to fertilization at an NF site, but not at a PF site. Key words: Blueberry (lowbush), fertilizer and soil nitrogen
DYNAMICS OF MICROBIAL BIOMASS AND FAUNAL POPULATIONS IN LONG-TERM PLOTS ON A GRAY LUVISOL
Authors: FYLES I. H. , JUMA N. G. , ROBERTSON J. A.
Published: March 2010

The dynamics of microbial biomass, nematode and microarthropod populations were studied in oat (Avena sativa L.) and second-year alfalfa (Medicago sativa L.) plots of a 5-yr rotation at Breton, Alberta. Plots were sampled at monthly intervals between July and October 1984. First cut of alfalfa was taken in early July. On average shoot biomass was higher in the oat plot (691 g m−2) than in the alfalfa plot (583 g m−2); root biomass (oat 263 g m−2, alfalfa 483 g m−2) was lower than shoot mass. The average microbial biomass (chloroform fumigation technique) in the surface soil (0–15 cm) was significantly greater (P < 0.05) in the oat plot (62 g m−2) than in the alfalfa plot (43 g m−2). Average nematode population over the 4-mo period was significantly greater (P < 0.05) in the oat plot (4.1 × 106 ind. m−2) than in the alfalfa plot (2.8 × 106 ind. m−2). Nematode numbers were significantly correlated with shoot production (r = 0.97*) in the oat plot but not in the alfalfa plot. Microarthropod populations were higher (P < 0.05), on average, in the oat plot (81 000 ind. m−2) than in the alfalfa plot (48 000 ind. m−2). Total microarthropod numbers were highly correlated with soil moisture in both plots (alfalfa, r = 0.82, P < 0.001; oat, r = 0.81, P < 0.001). Higher activity of the components in the oat relative to the alfalfa system suggests that significant biological differences between plots have arisen in less than 3 yr in response to differences in crops within the rotation. In addition, microbial and faunal populations differed in their responses to changes in the soil environment. Key words: Nematode, mite, collembola, fumigation, long-term rotation
THE IMPORTANCE OF EROSION IN THE CARBON BALANCE OF PRAIRIE SOILS
Authors: JONG E. DE , KACHANOSKI R. G.
Published: March 2010

Twenty-six cultivated benchmark sites established in the mid-1960s were resampled in the early 1980s. Most of the sites were coarse textured and field observations indicated that these were subject to wind erosion. The original samples and the samples collected in the 1980s were analyzed for 137Cs and organic C. From these data soil erosion or deposition and organic C losses from the 0 to 0.15-m layer were calculated. Soil losses up to 10 kg m−2 yr−1 were calculated, but some sites showed deposition. Changes in organic C in the 0 to 0.15-m layer could be explained largely by erosion and deposition, indicating that at these sites (mainly on upper or middle slopes that had been cultivated since before the mid-1940s) erosion was the major factor responsible for the observed organic C loss. Key words: Organic carbon loss, erosion, mineralization
ROOTING CHARACTERISTICS OF CORN, SOYBEANS AND BARLEY AS A FUNCTION OF AVAILABLE WATER AND SOIL PHYSICAL CHARACTERISTICS
Authors: DWYER L. M. , STEWART D. W. , BALCHIN D.
Published: March 2010

Root densities of field-grown corn, soybeans and barley were measured as functions of depth in four soils of different textures for 1 yr, and root depths were monitored for 2 additional years. General relationships were established between root depth, available soil water and soil texture. Maximum root depths were found to be inversely related to available water within the limits imposed by crop rooting habits and soil physical characteristics. Roots continued to develop during the reproductive growth phase and maximum root densities were found about the time of physiological maturity. Root distribution with depth was described for each crop on each soil using a modified exponential equation with an extinction coefficient specific to crop, growth stage and soil. Reasonable estimates of root distribution can be predicted from root density in the top layer using a crop-specific extinction coefficient in this modified exponential equation. Key words: Maximum root density, root distribution, rooting depth, nonlinear fitting
EFFECT OF VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI AND CAPTAN ON GROWTH AND N2 FIXATION BY Rhizobium-INOCULATED FIELD BEANS
Authors: KUCEY R. M. N. , BONETTI R.
Published: March 2010

The effects of rhizobium inoculation, vesicular-arbuscular mycorrhizal (VAM) fungi and seed-applied captan on field bean growth and N2 fixation were studied under greenhouse conditions. 15N isotope dilution methods were used to measure N2 fixation in a soil containing indigenous Rhizobium phaseoli. Inoculation of rhizobia onto host plants increased N2 fixation by 50 – 82 mg N per plant compared with uninoculated controls. The incidence of nodulation was also increased by R. phaseoli inoculation. Addition of VAM to the soils increased bean dry matter production by 9 – 54% over plants not receiving VAM, and increased the N2 fixed by rhizobially-inoculated plants by 4 – 27 mg N per plant. VAM addition resulted in greater uptake of soil N by the plants. Inoculation of captan-treated field beans with inoculum derived from a captan-tolerant strain of R. phaseoli did not result in improved N2 fixation rates compared with inoculation with the nontolerant parent strain. Seed-applied captan reduced the proportion of nodules formed by both strains of added rhizobia, but did not result in decreased amounts of N2 fixed by the root systems. Captan did not reduce the effectiveness of VAM. Key words: Rhizobium phaseoli, captan, VA mycorrhizae, N2 fixation, 15N
A RAPID METHOD FOR CATION EXCHANGE CAPACITY ESTIMATION OF MINERAL SOILS USING METHYLENE BLUE ADSORPTION
Authors: SOON Y. K.
Published: March 2010

A colorimetric method, based on methylene blue adsorption, for rapid analysis of soil CEC is described. The effect of soil pH and organic matter was examined by multiple regression. For 44 test samples CEC was predicted well from transmittance measured at 550 nm (r2 = 0.735**); the r2 increased to 0.815** by excluding two moderately calcareous soil samples, and to 0.872** by including organic matter as a second independent variable. Key words: Methylene blue adsorption, CEC, colorimetric method
STUDIES ON THE POTASSIUM-SUPPLYING CAPACITIES OF SOUTHERN ONTARIO SOILS. I. FIELD AND GREENHOUSE EXPERIMENTS
Authors: RICHARDS JOHN E. , BATES THOMAS E. , SHEPPARD S. C.
Published: March 2010

The response of grain corn (Zea mays L.) to applied K was studied for 10 yr on three southern Ontario soils. On a Conestogo L, the most profitable rate of K application was 2.5 times higher than expected and the critical concentration of NH4OAc-K, above which no response occurred to either applied K or increasing NH4OAc-K concentrations, was higher (2 ×) than expected, based on 1 M NH4OAc-extractable K and interpretation by the Ontario Ministry of Agriculture and Food soil test. All soils fixed substantial quantities of applied K, but the amount fixed by the Conestogo L was not greater than that fixed by the other two soils. When no K was applied, corn removed less nonexchangeable K (NEK) from the Conestogo L than from the other two soils. A greenhouse experiment was conducted to determine if either the availability of NH4OAc-K or NEK to alfalfa (Medicago sativa L. 'Banner') was lower on highly responsive soils than on less responsive soils. By the end of the experiment, soils on which crops were very responsive to applied K (Guelph L, Conestogo L, and Teeswater SiL) had supplied less K to alfalfa than had soils (Brookston L and Fox SL) on which response to applied K in field trials was similar to that predicted by the soil test. Total K uptake was related to NEK uptake suggesting that differences in the K-supplying capacities of the soils were associated with the availability of NEK to alfalfa. It was concluded that the responses to higher rates of applied K than expected in field trials were due to lower uptake of NEK. The clay mineralogy of the soils was dominated by illite with lesser amounts of vermiculite. No appreciable differences in mineralogy were found between the two groups of soils and NEK uptake was not significantly related to the amount of clay nor to the illite content of the coarse clay and fine clay fractions. Key words: NH4OAc-K, nonexchangeable K, illite, vermiculite, alfalfa, corn
CHARACTERISTICS OF TWO MAFIC SAPROLITES AND THEIR ASSOCIATED SOIL PROFILES IN CANADA
Authors: RUTHERFORD G. K. , THACKER D. J.
Published: March 2010

Two soil profiles developed from mafic saprolites were examined at Economy Mountain, Nova Scotia and Kamloops, British Colombia. The underlying rocks, a tholeiitic basalt in Nova Scotia and a basic greenstone schist at Kamloops, were apparently transformed to predominantly smectitic saprolites in pre-Holocene times. During the Wisconsinan glacial stage the sola and a significant portion of the saprolites were removed. Holocene pedogenesis has produced new sola on the saprolites. In Nova Scotia, the solum may have some locally derived till or colluvium component. Key words: Mafic pedogenesis, Paleosols, soil mineralogy
EFFECT OF PLANT ROOTS ON CHEMICAL AND BIOCHEMICAL PROPERTIES OF SURROUNDING DISCRETE SOIL ZONES
Authors: DORMAAR J. F.
Published: March 2010

The chemical and biochemical properties within and immediately adjacent to the root zone of two grass species were studied over a 5-wk period. The experiment utilized a simple container comprising five sandwiched compartments giving a center or "rhizosphere" zone, two intermediate zones, and two outer zones. Soil samples were taken from an Orthic Brown, Dark Brown, and Black Chernozemic Ah horizon and from the Orthic Dark Brown Chernozemic Ap horizons of the unfertilized part of a continuous wheat field and the fallow field of a wheat-fallow rotation, both under cultivation for 70 yr. The two grasses were blue grama (Bouteloua gracilis (H.B.K.) Lag.) and rye (Secale céréale L. 'Frontier'). High root densities were achieved by the end of the study, especially with the blue grama. Changes in pH over time were slight but consistent; they decreased in the Black Chernozemic soil and increased in the other soils. A redistribution of labile phosphorus was caused by the presence of the plant roots. The Orthic Dark Brown Ah and Ap horizon soils reacted differently to the conditions of the study. Monosaccharides always increased in the rhizosphere zone and generally decreased in the zone adjacent to the rhizosphere zone in the case of rye and in the outside zone in the case of blue grama. The ratio galactose + mannose/arabinose + xylose always increased towards the outer zone. Although the presence of roots influenced the measured chemical properties of the soil surrounding them, there were no overall common trends. The results, even in this simplified system, demonstrated complex and interrelated effects (P < 0.01) of soil type, plant species, and time on the biochemical dynamics in and near the rhizosphere. The properties of rhizosphere soil are system specific. To interpret the processes within the system, detailed knowledge of the soil organic matter, the physiology of the species root, and the effect on each other is obligatory. Key words: Rhizosphere, Chernozemic Ah/Ap horizons, blue grama, rye, monosaccharides
ESTIMATED LONG-TERM SOIL MOISTURE VARIABILITY ON THE CANADIAN PRAIRIES
Authors: JONG R. DE , BOOTSMA A.
Published: March 2010

Soil water contents under wheat production systems on the Canadian prairies were estimated using the Versatile Soil Moisture Budget, which was modified to include an estimated seeding date and a biometeorological time scale. Large year-to-year variability required the use of long term (60 yr) data to describe seasonal and probable occurrences of soil water contents for 27 stations. Regression and correlation analyses were used to simplify presentation of the data and to display their spatial distribution. On average, summerfallowing was most effective in conserving water in areas with intermediate spring soil water contents and on soils with a higher available water-holding capacity (AWC). In abnormally dry years (i.e., 10% probability) summerfallowing conserved more water in the wetter areas while increasing the AWCs had the greatest effect on conserved water in the intermediate areas. Soil water contents at heading were greater under wheat-fallow rotation compared to continuous wheat and increased with increasing AWCs. Water contents of less than 50% of AWC at heading occurred with a probability of 80% or higher in most areas, indicating some stress is experienced in most years. Summerfallowing lowered the probability only slightly on soils with a low AWC, but by 10–20% on the higher AWC soils. The probability of extreme water stress at heading (i.e. water contents ≤ 10% of AWC) ranged from 0% in the wettest areas to 40–60% in the driest climatic area. Key words: Soil water content, versatile soil moisture budget, summer fallowing, zonation, wheat (spring), seeding date
FIELD ESTIMATES OF AMMONIA VOLATILIZATION FROM SWINE MANURE BY A SIMPLE MICROMETEOROLOGICAL TECHNIQUE
Authors: GORDON R. , SCHUEPP P. , BRUNKE R. , LECLERC M.
Published: March 2010

An existing numerical model for particle diffusion into air from ground-based sources has been recalculated for circular source plots of 7 m diameter. Results show that a satisfactory relationship between horizontal flux of the diffusing gas at a single measuring height above the center of the plot and flux density from the plot can be defined. This provides a simple technique for comparing volatilization rates of ammonia from treated and untreated manure in the field, under outdoor conditions. The technique has been applied to the study of effects of monocalcium phosphate (MCP) addition on ammonia volatilization from swine manure (Sus scrofa domesticus). Mean ammonia flux densities during peak volatilization periods of the first 3 d after spreading were lower for MCP-treated plots by an average of 17%, with a maximum reduction of 30%. Variability of results from short-term sampling intervals (1–2 h) was high. This made short-term detection of differences of <20% difficult under the adopted experimental procedures. Observations for volatilization from source plots of equal source strength, as well as from source plots with different degrees of dilution of applied manure, permitted a further definition of the sensitivity of the technique. Suggestions are given for possible reductions in variability from improved experimental procedure. Key words: Ammonia volatilization, manure, monocalcium phosphate simulation of diffusion
EFFECTS OF VEGETATION ON PROPERTIES OF SANDY SOILS IN CENTRAL ALBERTA
Authors: FYLES J. W. , McGILL W. B.
Published: March 2010

It was hypothesized that topographic location, fire, species characteristics, and soil texture interacted to maintain stable vegetation patterns on the landscape. As a corollary, relationships would exist between specific vegetation and profile development patterns, they would not be masked by secondary succession, and they would explain the distribution of both plant communities and soil types in the landscape. This hypothesis was tested in a study of soils and vegetation at eight sites representing three forest types (pine/lichen; closed canopy jack pine; white spruce) on sand ridges near the town of Slave Lake, Alberta. Differences in profile characteristics among soils studied corresponded to differences in vegetation. Soils under white spruce and jack pine/alder forest showed evidence of greater translocation of amorphous iron and aluminum than soils under jack pine/lichen woodland. The fractionation of phosphorus among organic, Ca–, Al–, and Fe– phosphates differed between soils under the three forest types as did the development of a textural B horizon. Clay eluviation appeared to be dependent primarily on initial clay content of the parent material although a contributory influence of vegetation was suggested. Integration of processes involved in soil profile development with those controlling vegetation dynamics particularly fire behavior, appears to provide a conceptual basis for explaining the distribution of soils in the landscape of the study area. Key words: Central Alberta, vegetation, sandy soils, eluviation, phosphorus fractions, soil development, fire
SEASONAL SOIL ERODIBILITY VARIATION IN SOUTHWESTERN ONTARIO
Authors: WALL G. J. , DICKINSON W. T. , RUDRA R. P. , COOTE D. R.
Published: March 2010

A study was conducted to evaluate the potential seasonal variation in soil erodibility (K) for selected soils of southwestern Ontario. Field-plot data, laboratory flume/rainfall-simulator studies, and a K-factor prediction equation were used to assess the potential magnitude of the seasonal variation of soil erodibility. Field-plot studies for a Guelph loam soil revealed that values were highest in the winter-spring thaw period (March) with a ratio of K seasonal to K annual (Kc) of 10. Laboratory flume and rainfall simulations with Fox sand, Haldimand silty clay, and Colwood silt loam soils were conducted with soil moisture and internal drainage varied to simulate seasonal conditions. The results corresponded with those observed in the field study, with highest K values occurring under simulated winter-spring thaw conditions (values of Kc =.4 – 4.0) and lowest values under simulated summer conditions (Kc < 1). Seasonal K values were computed with a prediction equation for 17 soil textural classes. Soil structure and permeability parameters of the prediction equation were modified to reflect seasonal variability in these properties. The predicted Kc values were highest for the winter-spring thaw period and approximately equal for the spring and summer periods. Results indicate that soil erodibility varies significantly with seasonal soil conditions and the magnitude of seasonal differences changes with soil textures. Key words: Soil erodibility, field-plot erosion data, rainfall simulation, runoff flume
ROOT DISTRIBUTION OF AND WATER UPTAKE BY FIELD-GROWN BARLEY IN A BLACK SOLOD
Authors: SOON Y. K.
Published: March 2010

A field study was conducted in 1984 and 1985 to determine the spatial distribution with time of root length density of spring barley (Hordeum vulgare L.) growing in a Black Solod in northwestern Alberta. The weakly solonetzic Bnt horizon present in the solodic soil appeared not to inhibit root growth, and roots were present to 90 cm depth of soil. Drought in 1985 reduced root growth in general, and in particular in the surface soil (0 – 15 cm depth) between crop rows. Root growth in both years continued well after ear emergence and attained a maximum total length (14.5 and 9.5 km m−2 in 1984 and 1985, respectively) some time into grain-filling. Water uptake rates of up to 1.3 cm3 m−1 d−1 were observed; this maximum rate was associated with younger roots in the 60- to 90-cm depth in 1984. Low availability of subsoil water in 1985, however, resulted in low root density and water uptake rates in the 60- to 90-cm depth. The weighted mean uptake rate for the entire root system was slightly more than 0.4 cm3 m−1 d−1 in 1984 and about half that in 1985. Key words: Barley, Hordeum vulgare L., solonetzic soil, water inflow, root growth, root length density
A COMPARISON OF DRY AND WET ASHING METHODS FOR THE ELEMENTAL ANALYSIS OF PEAT
Authors: ALI M. W. , ZOLTAI S. C. , RADFORD F. G.
Published: March 2010

Peat samples were digested by dry and wet ashing for analysis by inductively coupled plasma spectrometry (ICP-AES). Results were comparable for Ca, Mg, Fe, K, Mn and P. Values for Zn, S, Cu, Ti, Na and Pb were consistently higher by wet ashing. Dry ashing gave much higher values for Al and Ni than wet ashing. Key words: Elements, wet ashing, dry ashing, peat, ICP-AES
EFFECTS OF CaCO3 AND P ADDITIONS ON CORN (Zea mays L.) GROWTH AND NUTRIENT AVAILABILITY OF A PODZOLIC SOIL
Authors: SIMARD R. R. , BATES T. E. , EVANS L. J.
Published: March 2010

A surface horizon from a Humo-Ferric Podzol was amended with 0 to 6 cmol kg−1 of CaCO3 and 125 to 500 mg P kg−1 to investigate their effects on the elemental composition and growth of corn and on nutrient availability. The addition of CaCO3 decreased the amounts of extractable P and Mn in the soil and the concentrations of P, K, Mn, Mg and Zn in the plants. The addition of P increased the dry matter yields, the amounts of available P in the soil and the concentrations of P and Mg in the plants, but decreased the concentrations of K, Mn and Zn in the seedlings. There were significant CaCO3 × P interactions on the amounts of extractable Mg and Zn in the soil and on the contents of N and Mn in the seedlings. The addition of 0.5 cmol CaCO3 kg−1 was beneficial to dry matter accumulation, but additions greater than 4 cmol kg−1 were excessive. The dry matter yields were most closely related to the amount of extractable P and to the activity of Mn2+ in solution. The concentration of P in the plants was very closely related to the amount of NaHCO3-extractable P in the soil. The concentration of Zn in the seedlings was most closely related to the amounts of DTPA-extractable Zn and of NaHCO3-extractable P. Key words: Liming, P fertilization, Zea mays (L.), plant nutrition, soil solution, Podzol
NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS
Authors: SINGH YADVINDER , BEAUCHAMP E. G.
Published: March 2010

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production