bluuebunny/crossref_metadata_2025 huggingface dataset:
A THEORETICAL AND WIND TUNNEL INVESTIGATION OF THE EFFECT OF CAPILLARY WATER ON THE ENTRAINMENT OF SEDIMENT BY WIND
Authors: McKENNA-NEUMAN C. , NICKLING W. G.
Published: March 2010

A theoretical model of the effect of small amounts of water on the threshold shear velocity of sand grains has been tested in wind-tunnel studies. The model is based upon the capillary forces developed at interparticle contacts surrounded by isolated wedges of water. These forces (Fc) are inversely proportional to moisture tension (P) and directly proportional to the geometric properties of the contacts (G). Given[Formula: see text]the cohesion of the material decreases with increasing moisture tension and particle angularity. The incorporation of this capillary force model into Bagnold's threshold model for dry particles gave a general relation which indicated that the threshold shear velocity of wet particles increases as the square root of the inverse of moisture tension. Laboratory measurement of the soil moisture characteristic curve of any sand therefore provides a simple, though indirect indication, of its susceptibility to entrainment by wind under low moisture conditions. Most sands appear to be exceedingly resistant to wind erosion at moisture tensions below 10 MPa or at gravimetric moisture contents above approximately 0.2%. Further work is needed to determine if this potentially practical relationship also applies to more complex agricultural soils. Key words: Aeolian, moisture tension, threshold shear velocity
THE ROLE OF VA MYCORRHIZAE IN THE ABSORPTION OF P AND Zn BY MAIZE IN FIELD AND GROWTH CHAMBER EXPERIMENTS
Authors: LU S. , MILLER M. H.
Published: March 2010

Two years of field experiments and one growth chamber experiment were conducted to determine the role of VA mycorrhizae in P and Zn absorption as well as the P-Zn interaction. The pattern of development of vesicular-arbuscular mycorrhizae (VAM) in the early growth stages of maize (Zea mays L.) plants in southern Ontario, Canada was investigated. The field experiments consisted of three fertility treatments, recommended phosphorus (RP), high phosphorus (HP) and HP plus zinc (HPZn). The RP and HP soils were used in the growth chamber experiment and Zn fertilizer was added to both RP and HP soils to have treatments of RP, HP, RPZn and HPZn. Benomyl was used in the second year of the field experiment and in the growth chamber experiment to reduce mycorrhizal infection. In the field experiment in 1987, 20% of the roots were colonized by VAM in the RP soil just 3 wk after sowing. At 40 d after sowing, about 50% of roots were infected. The HP treatment significantly reduced VAM infection intensity compared to the RP treatment. The addition of 40 kg Zn ha−1 to the HP soil had little effect on mycorrhizal infection intensity in either field or growth chamber experiments. However, Zn fertilization increased mycorrhizal infection in the RP treatment in the growth chamber experiment. Treatment with benomyl significantly decreased mycorrhizal infection, shoot dry weight, P concentration and P inflow in the RP soil, suggesting the fungal relationship is important for P absorption in this soil. There was no conclusive evidence that mycorrhizae are important for P absorption in the HP soil. Although HP treatment decreased VAM infection greatly in both field and growth chamber experiments, it did not affect the absorption of Zn. Benomyl did not affect the shoot Zn concentration in either field or growth chamber experiments, suggesting that mycorrhizae are not important in the absorption of Zn on this soil. Key words: VAM infection development, maize, P, Zn, benomyl
RESIDUAL PHOSPHORUS SOLUBILITY FOR AN ACID, CLAYEY, FORESTED SOIL IN THE PRESENCE OF OXALATE AND CITRATE
Authors: COMERFORD N. B. , SKINNER M. F.
Published: March 2010

A highly weathered, clayey soil was sampled 14 yr after a Pinus radiata stand was broadcast fertilized with 0, 50 and 200 kg P ha−1 as ordinary superphosphate. Incremental loadings of oxalate and citrate anions from 10 to 100 μmol of anion g−1 soil were evaluated for increased soluble, reactive P (SRP) and soluble, nonreactive (SNP) P. Sorption isotherms were compared to evaluate the effect of the previous fertilization on P sorption by the soil material sampled, and also to measure SNP displacement by orthophosphate-P. A portion of the SNP pool was more readily released than SRP and orthophosphate displaced a significant amount of SNP. After 14 yr the effect of fertilization was still obvious in the sampled soil material. Much of the organic anion-soluble P was in the SRP form. Key words: Citrate, organic P, orthophosphate, oxalate, Pinus radiata, residual P
EVALUATION OF CRITERIA FOR THE CLASSIFICATION OF GLEYSOLIC SOILS IN SASKATCHEWAN
Authors: MILLER J. J. , ACTON D. F. , ST. ARNAUD R. J.
Published: March 2010

Six soils within and adjacent to two willow-ring depressions in hummocky moraine of the Dark Brown soil zone were monitored for seasonal changes in water table levels, redox status, and soil temperature to evaluate color citeria for identifying saturated and reduced soils of the Gleysolic order. Soils in the center of the willow-ring depressions had water table levels close to the soil surface, Ept values of < 100 mV, and were covered by hydrophytic vegetation. Soils near the perimeter of the willow-ring depression had water table levels generally below 1 m, Ept values > 400 mV, and were covered by hydrophytic vegetation. Three of the depressional soils had matrix chromas of 1 in the Ae and/or Bt (Btj) horizons, with prominent rusty mottles, and met the color criteria of Humic Luvic Gleysols. The fourth depressional soil had matrix chromas of 1 in the Btj horizon, but no mottles were present within 50 cm of the soil surface, and met the color criteria of an Orthic Humic Gleysol. Two nondepressional soils, on lower slope positions just outside the willow-ring depressions, exhibited water table levels generally below 1.5 m, had an Ept of > 400 mV, and lacked hydrophytic vegetation. Of these, one soil had matrix chromas of 2 and prominent rusty mottles within 50 cm of the soil surface and met the color criteria of a Rego Humic Gleysol. The other had mottles of low chroma within 1 m of the surface and met the color criteria of a Gleyed Rego Dark Brown. Based on this study, the color criteria are adequate for depressional soils but are inadequate for the classification of soils beyond the willow-ring. Key words: Water table level, redox potential, soil temperature, morphological criteria, gleying
RIDGE-TILLAGE AND EARLY-SEASON SOIL MOISTURE AND TEMPERATURE ON A POORLY DRAINED SOIL
Authors: STONE J. A. , VYN T. J. , MARTIN H. D. , GROENEVELT P. H.
Published: March 2010

Adaptation of conservation tillage systems for corn (Zea mays L.) production on the poorly drained soils of southwestern Ontario is limited by excess soil moisture early in the growing season. Ridge-tillage appears capable of reducing early-season soil moisture in these soils. A study was conducted to evaluate the effect of corn residue management in a ridge-tillage system in comparison with fall-mouldboard-plow and zero-tillage on early season soil moisture and temperature of a Brookston clay loam (Orthic Humic Gleysol). Ridge-tillage resulted in lower early-season soil moisture and higher temperatures within the seed zone than zero-tillage but they were comparable to those from mouldboard-plow tillage despite the fact that ridging caused a significant increase in surface residue. Chopping corn stalks in the fall contributed to lower early season moisture and higher temperature within the ridge. Key words: Till-plant, residue management, corn, soybean, Zea mays L., Glycine max L.
EFFECT OF EDTA AND DTPA ON AVAILABLE-P EXTRACTION WITH THE KELOWNA MULTIPLE ELEMENT EXTRACTANT
Authors: LIEROP W. VAN
Published: March 2010

The objective of this study was to determine the effect of adding either 0.001M EDTA or 0.005M DTPA on the amount of P removed from acid and calcareous soils by the Kelowna and 0.25M HO Ac extractants. These complexing agents were studied for possible simultaneous extraction and determination of available Zn. To achieve that end, P-concentrations removed by these solutions from a group of acid, calcareous, and combined soils were compared against reference values obtained with 0.5M NaHCO3 (Olsen et al.) and the Kelowna extractant (0.25M HOAc + 0.015M NH4F) by means of graphing, correlation and regression techniques. Of the 80 soils studied, 40 were acid with pH (H2O) values ranging from 4.2 to 6.9 and the remainder having higher values up to 9.3. Results indicated that additions of either 0.001M EDTA or 0.005M DTPA to the Kelowna solution increased average extracted P concentrations by about 20 and 60%, respectively. Values removed by either of the new KEDTA and KDTPA solutions were closely related to those extracted with 0.5M NaHCO3 and Kelowna solutions on acid and calcareous soils (r values ≥ 0.96**). As EDTA and DTPA increased extracted soil P, these were added at 0.001 and 0.005M as NH4 preparations to 0.25M HOAc (AADTPA & AAEDTA; without fluoride), respectively, for determining whether these complexing agents could supplant F for P extraction. These solutions removed proportionally related amounts (r ≈ 0.94**) of P from calcareous, compared to the Kelowna and 0.5M NaHCO3 solutions, but relationships were less precise for acid soils (r ≈ 0.76**). These results suggest that the AADTPA or AAEDTA solution should be evaluated further before adoption for routine P determination in multiple element extractions. Key words: Mehlich in, acid soils, calcareous soils
MOISTURE-RETENTION PARAMETERS FOR COARSE-TEXTURED SOILS IN SOUTHERN ALBERTA
Authors: BENNETT D. R. , ENTZ T.
Published: March 2010

A combination of field and laboratory procedures was used to estimate moisture-retention parameters of four coarse-textured soil series in southern Alberta. In situ field capacity moisture content was substantially higher than estimates based on conventional laboratory methods, resulting in significant underestimation of total available moisture. Moisture-retention capacity of all four soil series was found to be adequate for irrigation development. Empirical equations were developed to estimate the upper and lower limits of moisture retention on the basis of particle-size distribution, as determined by the Bouyoucos hydrometer method. Five alternative empirical methods were also evaluated for use in predicting moisture-retention parameters of coarse-textured soils. Equations presented by Rawls et al. (1982) were found to have the best relationship with southern Alberta data for both field capacity and wilting point. Key words: Coarse-textured soils, moisture-retention parameters, particle-size distribution, empirical models, irrigation suitability
GROWTH AND YIELD OF MAIZE (Zea mays L.) GROWN OUTDOORS HYDROPONICALLY AND IN SOIL
Authors: MILLER M. H. , WALKER G. K. , TOLLENAAR M. , ALEXANDER K. G.
Published: March 2010

Maize (Zea mays L.) was grown outdoors hydroponically and in soil to compare yields in the two systems and to determine the extent to which soil temperature and plant nutrition limit yield of soil-grown plants. The hydroponic system consisted of 22.5-L plastic pails filled with "Turface" to which nutrient solution was added at least twice daily. In all 3 yr dry-matter accumulation throughout the growing season was greater on the hydroponic system than in well-fertilized, irrigated sandy-loam soil when planting pattern and density were the same. Maximum aboveground dry matter and grain dry matter on the hydroponic system were 25.8 and 12.2 Mg ha−1, respectively. It is apparent that there is a soil-based constraint that limits aboveground dry-matter production to 75–85% of the potential with the aboveground environment in the region. Grain yield appears to be limited to a lesser extent. To determine the effect of root-medium temperature, growth in pails buried in the soil was compared to that in soil and in pails placed on the soil surface. Although the temperature of the buried pails was consistently lower than that in the aboveground pails and in the soil, dry matter accumulation was similar to that in the aboveground pails indicating that soil temperature was not a cause of the lower yield of the soil-grown plants. There was no evidence that plants growing on the highly fertilized soil were nutrient limited at any growth stage. Other studies have indicated that transient water stress on soil-grown plants will not explain the difference in growth on the two systems. Key words: Maize, hydroponics, soil limitations, soil temperature, nutrition
DENITRIFICATION IN LOWBUSH BLUEBERRY SOILS
Authors: EATON LEONARD J. , PATRIQUIN DAVID G.
Published: March 2010

Effects of environmental variables on denitrification in acid (pH 4.0–5.5), infertile soils of lowbush blueberry (Vaccinium angustifolium Ait.) stands were investigated under laboratory conditions. All soils produced N2O when nitrate was added and samples were waterlogged and incubated for 2 d at temperatures of 20 °C or greater. No N2O production occurred at temperatures of 15 °C or lower. Nitrous oxide was the main gas evolved at the natural pH levels of these soils. Mercuric chloride inhibited nitrous oxide evolution. Raising soil pH resulted in increased rates of denitrification, and in more conversion of nitrous oxide to dinitrogen. Soil taken from a site that had been fertilized repeatedly exhibited higher rates of N2O evolution than did soil from a site that had never been fertilized. N2O production from waterlogged samples without added nitrate was positively correlated with percent organic matter and nitrate concentration of soils at the time of sampling. In a field experiment, more N2O was produced by samples from fertilized plots than by those from unfertilized plots, but absolute values from both types of plots were low. Key words: Nitrous oxide, pH, nitrate, moisture
TITRATIONS OF ORGANIC SOILS WITH STANDARD BASE: SOLUBILITY OF IONIZABLE FUNCTIONAL GROUPS AT 25 °C
Authors: GAMBLE DONALD S.
Published: March 2010

The conversion of undissolved acidic functional groups into dissolved carboxylate anions has been monitored during potentiometric titration of a Typic Mesisol Peat at 25 °C. The analytical chemical calculations of total acid functional groups and of H+ dissociation equilibrium functions take the dissolution process into account. With 0.05 g of sample suspended in 20 mL of 0.1 N NaCl, the molarity of carboxylate anions in the external solution ranged from 4.3 × 10−4 M at 1 mL g−1 0.1 N NaOH, to 1.5 × 10−3 M at 6 mL g−1 0.1 N NaOH. The corresponding amounts of undissolved carboxyl groups were 5.2 × 10−4 and 1.0 × 10−4 mol g−1. Differential acid constants (KGA) for the undissolved carboxyls were 7.6 × 10−4 (σ 1.4 × 10−4) for αG < 0.02 (0.016 – 0.02) and 1.4 × 10−5 (σ 0.04 × 10−5) for αG > 0.026 (0.026 – 0.60). A substantial increase in productivity was achieved by means of an automatic titrator and a microcomputer with spreadsheet software. Types of data production and processing that were previously labor intensive have now become much more practical. Key words: Organic soils, organic matter solubility, organic soil carboxyls, organic soil ion exchange, organic soil titration, pH dependent solubility
EFFECTS OF CROPPING ON CARBOHYDRATE CONTENT AND WATER-STABLE AGGREGATION OF A CLAY SOIL
Authors: ANGERS D. A. , MEHUYS G. R.
Published: March 2010

In a previous study, the mean weight diameter of water-stable aggregates of a clay soil was increased by up to 50% after two growing seasons under barley and alfalfa compared to fallow or corn. The objective of the present study was to determine whether rapid changes in water-stable aggregation under different crops were related to changes in soil carbohydrate content. Compared to fallow or corn, cropping to barley and alfalfa for 2 yr did not affect the soil C and N contents but significantly increased carbohydrate content by up to 25%. The correlation (r = 0.63, P = 0.001) between aggregate mean weight diameter and carbohydrate content suggested that at least part of the change in water-stable aggregation was related to carbohydrates. Treatment of the soil with sodium periodate prior to wet-sieving confirmed the partial involvement of carbohydrates in the stabilization of aggregates by crops. The remainder of the crop effect on aggregation was removed by sodium tetraborate which suggests that more-humified, though ill-defined, organic substances were also involved. Key words: Carbohydrates, aggregate stability, barley, alfalfa, corn, periodate
FIXATION AND IMMOBILIZATION OF RECENTLY ADDED IN SELECTED ONTARIO AND QUEBEC SOILS
Authors: DRURY C. F. , BEAUCHAMP E. G. , EVANS L. J.
Published: March 2010

Low recovery of recently added [Formula: see text] fertilizer as [Formula: see text] was observed in a Bainsville (Orthic Humic Gleysol) and a Dalhousie (Gleyed Eutric Brunisol) soil, whereas a Brookston (Orthic Humic Gleysol) and a Conestogo (Gleyed Melanic Brunisol) soil had a high recovery. The former two soils had higher vermiculite contents than the latter two soils. Therefore, [Formula: see text] fixation was believed to be responsible for the low recovery. Between 18 and 23% of added [Formula: see text] was fixed after 15 d in the Bainsville and Dalhousie soils whereas only 1–3% of added [Formula: see text] was fixed in the Brookston and Conestogo soils. Potassium pre-addition (with/without air drying) increased the apparent recovery in the Bainsville and Dalhousie soils but did not affect the actual recovery. Potassium pre-addition did not block subsequent [Formula: see text] fixation, rather it resulted in a release of native 14N. Gamma irradiation was used to inhibit biological activity. Between 1 and 7% of added 15N was immobilized in these soils after 15 d. Key words: Ammonium fixation, immobilization, vermiculites, 15N gamma radiation, potassium, native N, ammonium exchange
DISTRIBUTION AND MOBILITY OF PHOSPHORUS IN GRASSLAND AND FOREST SOILS OF SASKATCHEWAN
Authors: FROSSARD E. , STEWART J. W. B. , ST. ARNAUD R. J.
Published: March 2010

Soil phosphorus transformations and losses were measured in three profiles representative of an environmental gradient covering a grassland to forest transition: a Calcareous Brown, an Orthic Black and an Orthic Gray Luvisol. A sequential extraction procedure was used to measure the different forms of both inorganic (Pi) and organic (Po) phosphorus present in soil horizons. The mobilities of phosphate anions and of some selected (Po) compounds (glucose 6-phosphate, choline phosphate and adenosine triphosphate) were estimated through isotopic dilution kinetic experiments, and indicated that all the tested Po compounds had a higher mobility than phosphate anions in B horizons; also, Po was predominant over Pi in the water extracts from these soils. A mass-balance approach (Pedogenic Index) which incorporates depth-bulk density parameters in measuring the composition of soil horizons was used to calculate losses of Pt and apatite-P (HCl-Pi). Both grassland soils behaved similarly; they lost 500–550 kg P ha−1 (20%) of their original Pt and 30% of the initial HCl-Pi fraction was either transformed to various other forms of P or lost from the solum. Losses of Pt (3020 kg P ha−1: 41 %)and of HCl-Pi (70%) were much higher in the Gray Luvisol. Since losses of Pt could not be due to leaching of phosphate anions through the profile, the importance of Po in P leaching should be considered along with surface runoff in determining the fate of P in these soils. Key words: Pedogenic index, P mass balance, P fractionation, organic P leaching, P mobility
INCREASED YIELDS AND PHOSPHORUS UPTAKE BY WESTAR CANOLA (Brassica napus L.) INOCULATED WITH A PHOSPHATE-SOLUBILIZING ISOLATE OF Penicillium bilaji
Authors: KUCEY R. M. N. , LEGGETT M. E.
Published: March 2010

Greenhouse and field experiments were conducted to evaluate the effect of inoculation with a phosphate-solubilizing isolate of Penicillium bilaji on the yield and phosphate uptake by canola (Brassica napus L.). Under greenhouse conditions, P. bilaji inoculation did not affect canola pod or straw dry matter production, but did increase straw and pod P concentrations resulting from increased P uptake over uninoculated treatments. Addition of P at 20 mg kg−1 soil as Florida rock phosphate plus inoculation with P. bilaji resulted in P uptake by canola nearly equivalent to that resulting from the addition of monoammonium phosphate (MAP) alone at the same rate of P. Addition of Florida rock phosphate alone had much less effect on plant P uptake. Addition of P. bilaji generally increased dry matter yields and P uptake by canola in two field sites. Penicillium bilaji appears to be able to increase the uptake of P from sources unavailable for plant uptake; P uptake by control plants inoculated with P. bilaji absorbed as much P as that absorbed by uninoculated plants receiving MAP. Key words: Penicillium bilaji, Brassica napus, fertilizer efficiency, rock phosphate, monoammonium phosphate
NITROGEN TRANSLOCATION IN AN ORTHIC FERRO-HUMIC PODZOL AFTER UREA FERTILIZATION
Authors: SWIFT D. E. , KRAUSE H. H.
Published: March 2010

Sampling of soil 9 yr after a high-rate urea application showed a significant increase in total N content and a decrease of the C:N ratio in the Bhf horizon. This change corresponded to a gain of 368 kg of N ha−1 in the 3-cm thick, sampled portion of this horizon. The changes in N status were accompanied by a general darkening of the soil. It is assumed that both fertilizer N and indigenous forest floor N were translocated to the B Horizon after the treatment. Key words: Forest fertilization, nitrogen, nutrient cycling, urea
ACKNOWLEDGMENT OF REVIEWERS
Authors: M merv
Published: March 2010

not available
SURFACE STRENGTH OF A WATER-SATURATED BED OF GLASS BEADS WHEN POLYACRYLIC ACID IS COVALENTLY BONDED TO THE BEADS
Authors: KOCH J. T. , KAY B. D. , LANGE G. L.
Published: March 2010

According to Emerson's model of the soil aggregate, a large soure of physical weakness exists at the surface of sand particles within the aggregate, particularly when wet. The aim of this study was to simulate sand particles with glass beads and to test the hypothesis that a bed of glass beads can resist large compressive forces in water when a polymer is bonded to the bead surfaces using chemicals and conditions that produce hydrolytically stable, covalent bonding. Because carboxyl and amine functional groups can react to form the amide bond and silanes can bond to a silanol surface (e.g., sand or glass), polyacrylic acid (PAA: FW ≈ 50 000), amines, and silanes were used to test the hypothesis for glass beads (53-μm mean diameter). The pressure at which the bed surface of the glass beads (when water-saturated) was penetrated with a flat probe (radius = 1.37 mm) served as an index of strength imparted by various chemicals when these were introduced into the system individually and in various combinations. A dramatic increase in the strength of the bed surface occurred only when all the theoretical requirements were met for both covalent bonding between the polymer and the silane and silanol coupling between the silane and the glass surface. We conclude that the hypothesis is confirmed for a simple system of glass beads and that large increases in the efficiency of soil conditioners may be potentially realized in soil aggregates if the weak links between inorganic particulates (sand, silt, and clay particles) and organic polymeric materials (natural or synthetic) are augmented with, or replaced by, strong and water-resistant links. Key words: Soil structure, soil conditioners, polymers, coupling agents, soil aggregates
STUDIES ON THE POTASSIUM-SUPPLYING CAPACITIES OF SOUTHERN ONTARIO SOILS. III. MEASUREMENT OF AVAILABLE K
Authors: RICHARDS JOHN E. , BATES THOMAS E.
Published: March 2010

This study was conducted to determine which of eight different extractants best described the K-supplying capacities of nine southern Ontario soils. The total amount of K extracted by eight crops of alfalfa grown in the greenhouse was related to soil K by regression techniques. The following procedures extracted increasingly higher average amounts of soil K: water; electro-ultrafiltration (EUF) at 20 °C (EUF-K-20) (37 μg K g−1); EUF at 80 °C (EUF-K-80) (83 μg K g−1); 2M NaCl (89 μg K g−1); 1M NH4OAc (131 μg K g−1); 0.1 M HNO3 (163 μg K g−1); seven sequential 7-min extractions with boiling 1 M HNO3 (Mactotal) (940 μg K g−1); and 0.2 M sodium tetra-phenyl boron (NaTPhB) (3248 μg K g−1). Of the eight extractants tested, the amount of K removed by EUF was the most closely associated to total K uptake; a multiple regression model with the logarithm of EUF-K-20 and the logarithm of EUF-K-80 as independent variables explained 97% of the total variation in K uptake. The K extracted by 2 M NaCl and by 0.1 M HNO3 also explained more variation in total K uptake (r2 = 0.86, and 0.92, respectively) than did 1 M NH4OAc (r2 = 0.61), which is currently used in the Ontario soil test program. The other extractants did not offer an improvement over NH4OAc, with the exception of the most soluble fraction of Mactotal (StepK). Extraction of soil K with electro-ultrafiltration may offer a more precise estimation of the K supplying capacities of southern Ontario soils than the currently used extractant. Key words: Electro-ultrafiltration, nonexchangeable K, ammonium acetate, soil test
A PROPOSED METHODOLOGY FOR ASSESSING THE RELATIVE IMPACT OF ACID RAIN AND NITROGEN FERTILIZERS ON ACIDITY OF AGRICULTURAL SOILS IN CANADA
Authors: COOTE D. R. , SINGH S. SHAH , WANG C.
Published: March 2010

Acid rain and N fertilizers both contribute to soil acidity, but no method has been available to compare their relative impacts. A simple model (SOLACID) is presented to assess quantitatively the acidifying effects of precipitation and N fertilizers on agricultural soils. Acid rain has been treated as a dilute solution of NH4NO3, (NH4)2SO4 and associated acids. Soil and plant pathways are considered for [Formula: see text], [Formula: see text]and [Formula: see text] by way of leaching, gaseous losses from microbial reduction, plant uptake and removal, and organic immobilization and mineralization. Leaching of [Formula: see text] was the factor to which the model was most sensitive. A relationship between base saturation and base cation leaching is described. Field data reported from 21 treatments at six experimental sites were used to test the model, which provided reliable estimates of final pH (r2 = 0.92**) and of changes in base saturation (r2 = 0.86**). Compared with previously published methods, the model provided the best estimates of lime requirements as computed from field measurements (r2 = 0.87**). Key words: Ammonia, sulfate, leaching, nitrification
THE CHARACTERIZATION OF SOIL MACROPOROSITY WITH CT SCANNING
Authors: GREVERS M. C. J. , JONG E. DE , ST. ARNAUD R. J.
Published: March 2010

The soil macropore system was analyzed with the help of image analysis, comparing images from computed-tomography (CT) scanning with images obtained from thin sections. The images obtained with the two methods were analyzed with an image analyzer (IBAS 2000) for various pore characteristics. Macroporosity measurements obtained with CT scanning were comparable with those obtained with thin section. Computed-tomography scanning of soil cores which had been impregnated with styrene resin revealed a decreased level of soil macroporosity, in particular of planar macroporosity, as compared to nonimpregnated soil cores. CT scanning provided a useful method in characterizing a compacted soil layer. Through three-dimensional analysis of the CT scans, boundaries of compacted soil layers could be identified to the nearest 1 mm. The advantages of this method are that it is nondestructive, and fast, images can be made at 1-mm intervals, and it has the capability for three-dimensional images. However, resolution is limited to pores larger than 750 μm. Key words: Soil porosity, image analysis, thin sections, CT scanning
SEDIMENT AND RUNOFF WATER CHARACTERISTICS AS INFLUENCED BY CROPPING AND TILLAGE PRACTICES
Authors: BEKE G. J. , LINDWALL C. W. , ENTZ T. , CHANNAPPA T. C.
Published: March 2010

Rainfall simulation by sprinkler irrigation was used to evaluate the characteristics of sediment and runoff water from erosion plots on a Dark Brown Chernozemic soil near Lethbridge, Alberta. Replicated land treatments consisted of bare fallow, perennial alfalfa/wheat grass forage (Medicago sativa L./Agropyron riparium Scribn. & Smith) planted in rows parallel to the slope, barley (Hordeum vulgare L.) planted in rows parallel to the slope (barley-S) and barley on contour (barley-C). The eroded sediment from all four treatments was generally enriched in organic matter (OM), NH4-N, total N (TN), and PO4-P, but not in NO3-N or total P (TP). The sediment from the bare fallow treatment was enriched in silt-size particles and had the highest OM enrichment. Maximum NH4-N and TN enrichment occurred in the sediment from the barley-S treatment, and maximum PO4-P in that from the forage treatment. This selective removal of plant nutrients was attributed mainly to erosion processes and to cropping-induced differences in C:N:P ratios of organic complexes. The runoff water from all four treatments was enriched in NO3-N, TN, and PO4-P. For the three cropping treatments in this experiment, nutrient enrichment of the runoff water decreased from forage > barley-S > barley-C treatment. In general, more NO3-N was lost in the runoff water than in the sediment. Key words: Erosion, sediment quality, water quality, nutrient loss, nitrogen forms, phosphorus forms.
THE KINETICS OF NONEXCHANGEABLE POTASSIUM AND MAGNESIUM RELEASE FROM QUEBEC SOILS
Authors: SIMARD R. R. , ZIZKA J. , KIMPE C. R. DE
Published: March 2010

Ligands such as complexing organic acids play a significant role in the dynamics of release of plant nutrients in soils. The objective of this work was to study the dynamics of slowly exchangeable K and Mg release from 12 Quebec soils by ten successive extractions with 5 × 10−4 M citric acid, over a period of 1800 h, and by a single extraction with boiling 1.0 M HNO3. All soils were characterized by a mixed clay mineralogical composition with swelling minerals as major components. The kinetics of slowly exchangeable K and Mg cumulative release were described using two forms of the Elovich, the parabolic diffusion, power function, and first and zero order equations. Comparisons of r and SE values showed that the extended form of the Elovich equation best fitted K and Mg release to citric acid. The amount and rate of K release by the citric acid procedure were highly correlated to the amounts of slowly exchangeable HNO3-extractable and rapidly exchangeable NH4OAc-extractable K and to the coarse clay content of the soils. The amount of Mg released to citric acid was proportional to the unbuffered cation exchange capacity of the soils. The results indicated that the citric acid procedure was a time saving alternative to the study of the kinetics of slowly exchangeable K and Mg release from soils. Key words: Nonexchangeable K, citric acid, nonexchangeable Mg, podzolic soils, kinetics
EFFECT OF pH, CALCIUM CONCENTRATION AND TEMPERATURE ON THE HYDROLYSIS OF DICALCIUM PHOSPHATE DIHYDRATE
Authors: MORDEN G. W. , RACZ G. J.
Published: March 2010

The rate of hydrolysis of DCPD to OCP in solutions of different pH values, calcium concentrations and temperatures was studied. Rates of hydrolysis were very slow at pH 6.0, relatively rapid and similar at pH 7.0 and 8.0, much slower at 10 °C than at 20 or 30 °C, and only slightly increased by increasing calcium concentration. Key words: Dicalcium phosphate dihydrate, hydrolysis, pH, temperature, calcium concentration
IDENTIFICATION OF K DEFICIENCY IN BRITISH COLUMBIA APPLE ORCHARDS
Authors: NEILSEN G. H. , HOYT P. B. , HOGUE E. J.
Published: March 2010

K deficiency was identified for the first time in British Columbia orchard soils. Greenhouse-grown apple seedlings responded to K in soils low in available K. MacSpur McIntosh (Malus domestica Borkh.) had increased leaf K (above deficiency) and improved initial fruiting after surface applications of KCl in an orchard with low soil K. Key words: Potassium deficiency, apple, leaf and soil potassium
RENDEMENT ET QUALITÉ DU TABAC À CIGARETTE FERTILISÉ AVEC DIFFÉRENTES FORMES D'AZOTE
Authors: LAMARRE MICHEL , PAYETTE SUZANNE
Published: March 2010

The effects of three forms of nitrogen on flue-cured tobacco production were observed for 5 yr. Significant effects were obtained for yield, quality, gross return and total nitrogen. No significant differences were found for maturity, total alkaloids or reducing sugars. The data showed that the use of a fertilizer containing 75% nitrogen in the form of [Formula: see text] or urea and 25% as [Formula: see text] produces a tobacco with acceptable agronomic and chemical characteristics. Key words: Flue-cured tobacco, nitrogen forms, nitrogen sources, nitrate [Formula: see text], ammonium [Formula: see text], urea
VARIATION SAISONNIÈRE DES ÉLÉMENTS NUTRITIFS DANS UN SOL EN PRODUCTION DE TABAC À CIGARETTE
Authors: LAMARRE MICHEL , PAYETTE SUZANNE
Published: March 2010

During 5 yr, the seasonal distribution of N, P, K, Ca, and Mg and changes in soil pH in soil fertilized for flue-cured tobacco were investigated. Soil samples were taken periodically during the growing season at three depths. There was no movement of N, P, K, Ca, or Mg below 20 cm from the point of fertilizer application when the total rainfall during the 7 wk after transplanting tobacco was less than 180 mm and was fairly evenly distributed in amounts of 25 mm or less. When showers were concentrated over a shorter period and were more abundant, there was some leaching of N, K, Ca, and Mg. Rainfall conditions which were favorable for leaching of N had no influence on the movement of P. Key words: Flue-cured tobacco, nitrogen (NO3), phosphorus, potassium, calcium, magnesium, pH.
A MATHEMATICAL MODEL TO ESTIMATE AGGREGATE BREAKDOWN DURING SOIL SIEVING IN A MODIFIED RAPD3 ROTARY SIEVE
Authors: BLACK J. M. W. , BARAGAR F. A. , CHANASYK D. S.
Published: March 2010

The percentage of soil material > 0.84 mm obtained by dry sieving is commonly used as an index of the wind erodibility of soils. Present sieving procedures do not account for the breakdown of friable aggregates during sieving so that results do not necessarily represent aggregation in the original sample. An equation was fitted to soil sieving data from a modified rapid rotary sieve. It successfully evaluated aggregate attrition during sieving for 397 out of 404 samples representing a wide variety of textures. Good reproducibility of results using the methodology was obtained for 45 paired soil samples. Results obtained employing the new method will relate more closely to field conditions allowing a better estimate of soil erodibility. Key words: Wind erosion, aggregate breakdown, sieving, soil erodibility, modified rapid rotary sieve
RELATIVE EFFICIENCY OF FERTILIZER N AND SOIL NITRATE AT VARIOUS DEPTHS FOR THE PRODUCTION OF SOFT WHITE WHEAT
Authors: CAREFOOT J. M. , ENTZ T. , BOLE J. B.
Published: March 2010

Soft white wheat was grown on a clay loam soil for 2 yr with a wide range of soil nitrate (SN) (70–280 kg ha−1) and fertilizer nitrogen (FN) (0–400 kg ha−1) treatments The field experiment was designed to determine the slopes of the yield response curves to FN (δy/δFN) and to SN (δy/δSN), to determine how the ratio of (δy/δSN)/(δy/δFN), or marginal rate of substitution, is affected by FN, SN, and depth of SN and to determine if refinements to the current FN recommendations for irrigated soft white wheat are required. The δy/δFN values in both years were high at low levels of FN and SN but declined as FN and SN increased. The δy/δSN in 1985 when most SN was situated in the 0- to 30-cm soil layer was initially high (26.0) at low levels of SN but rapidly declined as SN increased. The δy/δSN in 1986, when most SN was situated in the 30- to 120-cm soil layer, was intially low (6.0) but increased as SN increased. Since the δy/δFN and δy/δSN values were sensitive to changes in FN and SN as well as the depth of SN the MRS values were variable in both years. The δy/δSN increased as SN increased when SN was situated in the 30- to 120-cm soil layer so there was only a small effect of depth of SN on FN recommendations. The FN at maximum profit occurred at a greater combined amount of SN and FN for the higher SN levels in both years. This preliminary field study suggested that fertilizer N recommendations could be improved by using an equation for predicting FN that considers a variable yield response to FN and SN, an interactive effect of FN and SN on yield, and an effect of depth of SN on yield. Key words: Soil nitrate, fertilizer nitrogen, soft white wheat, soil test N
EFFECT OF SELENATE VS. SELENITE FORMS OF SELENIUM IN INCREASING THE SELENIUM CONCENTRATION IN FORAGES AND CEREALS
Authors: GUPTA UMESH C. , WINTER K. A.
Published: March 2010

A greenhouse study was conducted on a fine sandy loam to determine the effect of adding different sources of Se on the Se concentration of forages and cereals. The three sources of Se were: NH4NO3 prills containing (i) 1.20% Se as sodium selenate, (ii) 1.02% Se as sodium selenite and (iii) urea prills containing 1.00% Se as sodium selenite. Application of 20 g Se ha−1 as sodium selenate (source i) produced Se concentrations of 1.02 and 1.05 mg kg−1 in timothy and 1.04 and 0.55 mg kg−1 in alfalfa in the two cuts, respectively, and 0.78 mg kg−1 in barley grain. This application rate of Se in the form of selenite resulted in 0.07–0.09 mg Se kg−1 in the two forages and barley grain. At similar application rates of Se, the ammonium nitrate doped with sodium selenate produced about 5–18 times more Se in the forages and barley than when doped with sodium selenite. Overall no significant difference was found in the plant Se concentration between ammonium nitrate or urea prills as the carrier for selenite. Key words: Sodium selenate and selenite doped NH4NO3, greenhouse, Se in forages and cereals
NITROGEN ADDITIONS AND LOSSES TO DRAINAGE IN ORCHARD-TYPE IRRIGATED LYSIMETERS
Authors: STEVENSON D. S. , NEILSEN G. H.
Published: March 2010

Controlled fertilizer nitrogen (N) inputs and releases to drainage waters were recorded for 9 yr in orchard-type lysimeters. Irrigations were varied year by year from about 37 to 100% of the maximum for the area. One apple tree per lysimeter was the test crop. Large amounts of drainage resulting from the highest levels of irrigation carried the largest amounts of nitrate [Formula: see text] to groundwater but when irrigation was less than 75% of maximum much smaller annual amounts appeared in drainage, mostly because drainage was small. Year 1 of drainage, although light, carried substantial amounts of [Formula: see text] out of the lysimeters probably reflecting mineralized native organic N plus applied N. The largest single influence on the retention of N was the presence of a cover crop. In 9 yr, 40 – 45% of applied N reappeared in drainage waters under grass while 88 – 115% of applied N reappeared under bare soil. The quantities of applied N (N1 = 162 kg N ha−1; N2 = 324 kg N ha−1) had less influence than the cover crop. The importance of measuring and sampling every drainage event because of wide ranges of [Formula: see text] concentrations is emphasized. Averaging could be misleading. The potential impact of [Formula: see text] releases to the aquatic environment of the watershed is discussed briefly. Key words: Nitrogen losses, lysimeters, irrigation, watershed, nitrate
ASSESSMENT OF A COMBINATION OF WET SIEVING AND TURBIDIMETRY TO CHARACTERIZE THE STRUCTURAL STABILITY OF MOIST AGGREGATES
Authors: POJASOK T. , KAY B. D.
Published: March 2010

A method of measuring the structural stability of moist soils using a combination of turbidimetry and wet sieving has been developed and assessed. Aggregates of 1–2 mm in diameter are shaken end-over-end in test tubes and dispersed clay and stable aggregates greater than 0.25 mm diameter measured. Stabilities determined using this method were compared to stabilities determined using a modification of the Yoder wet-sieving method on 20 soils of different textures, organic-matter content, and recent cropping history. Wet aggregate stabilities determined by the two methods were correlated although the two measurements exhibited different sensitivities to clay content, organic-matter content and moisture content at the time of sampling. Dispersible clay was found to be a function of total clay content, organic-matter content and water content at the time of sampling. The new method offers the advantage of stability measurements of structural units of much different size using the same energy input and can be readily adapted to the routine analysis of a large number of samples without a large investment in equipment or space. Key words: Wet aggregate stability, dispersible clay, cropping history, soil structure
EFFECT OF HETEROTROPHIC BACTERIA ON DIFFERENT HUMIC SUBSTANCES IN MIXED BATCH CULTURES
Authors: KONTCHOU C. YANZE , BLONDEAU R.
Published: March 2010

Humic substances extracted from different soil samples and synthetic humic compounds (two melanoidins and one synthetic polymer) were used as the sole carbon source in liquid media inoculated with a mixed bacterial community selected by adaptation culture technique, and incubated for 90 or 100 d. The results show a high resistance to degradation of humic compounds by heterotrophic bacteria. Only a slight decrease in carbohydrate content and some modifications in carboxyl content were observed with the natural compounds. This resistance to biodegradation does not seem to be related to sample origin (e.g., forest humic substances compared to cultivated soil humic substances), or extraction procedure (sodium pyrophosphate compared to sodium hydroxide). Fulvic acids were as refractory as humic acids. The action of heterotrophic bacteria on incubated humic substances was similar under anaerobic (with nitrate reducing conditions) and aerobic conditions. Key words: Fulvic acids, humic acids, humus recalcitrance, melanoidins
FACTORS INFLUENCING THE SURVIVAL AND ACTIVITY OF A PENTACHLOROPHENOL-DEGRADING Flavobacterium sp. IN SOIL SLURRIES
Authors: TOPP EDWARD , HANSON RICHARD S.
Published: March 2010

The effects of soil type, supplementation with carbon or inorganic nutrients, creosote, and copper/chromate/arsenate (CCA) mixtures, on viability and pentachlorophenol (PCP) degradation by inoculants of a PCP-degrading Flavobacterium sp. were examined in phosphate-buffered soil slurries. Populations of 108Flavobacterium/mL in non-sterile slurries prepared with clay loam, silt loam, or loamy sand declined by at least 95% within 3 d. Populations were stable for at least a week in heat-sterilized clay loam slurries but addition of non-sterile soil resulted in rapid death of the Flavobacterium sp. Supplementation with 4 g L−1 Na-glutamate or glucose, promoted the growth of the Flavobacterium sp. in non-sterile clay loam slurries. Supplementation with 1 g L−1 Na-glutamate, glucose, or p-hydroxybenzoate stimulated PCP degradation when the Flavobacterium sp. was inoculated at ≥ 108 cells mL−1 and the PCP concentration was less than 150 mg L−1. Addition of [Formula: see text], [Formula: see text], Mg2+, and Fe2+ together did not stimulate growth. Populations of culturable indigenous bacteria were larger in soil containing 50–300 mg L−1 PCP than in controls. Addition of PCP favored the predominance of one colony type identified as a pseudomonad. Creosote of CCA mixtures, pollutants often found together with PCP contamination, were inhibitory to the Flavobacterium sp. in soil extract. Key words: Pentachlorophenol, biodegradation, Flavobacterium, soil slurries
TECHNIQUES FOR SPEEDING THE MOVEMENT OF LIME INTO AN ORCHARD SOIL
Authors: HOYT P. B. , DROUGHT B. G.
Published: March 2010

Many soils in orchards in southern British Columbia are acidic, especially those with sandy texture. Most orchards have vegetative ground cover. A field experiment was therefore undertaken on a sandy soil to determine the most effective method of getting lime into the rooting zone of fruit trees without damaging their roots. Applying lime on the grass surface at 3.6 t ha−1 was as effective in reducing soil acidity of the 0- to 25-cm horizon as incorporating lime into the soil. Calcium hydroxide, calcite and dolomite were all equally effective in raising soil pH. Doubling the liming rate greatly increased the downward neutralization of soil acidity and movement of Ca and Mg. The pH was raised by about 1 unit throughout the profile by the higher rate of Ca(OH)2, (7.2 t ha−1). Ammonium sulphate detracted from the benefits of liming, with the 200 kg N ha−1 rate causing a significant depression in pH at the 0- to 20-cm depth. Ammonium nitrate had a smaller adverse effect. Hence, neutralization of soil acidity in the upper rooting zone of fruit trees can be accomplished in only a few years by applying high rates of lime on the grass surface and by using the lesser acidifying N fertilizers. Key words: Liming materials, application methods, N fertilizer
LOAMY SUBSTRATA AND FOREST PRODUCTIVITY OF SANDY GLACIAL DRIFT SOILS IN MICHIGAN
Authors: FARRISH K. W. , DOOLITTLE J. A. , GAMBLE E. E.
Published: March 2010

The study was conducted to ascertain the effect on forest productivity of underlying finer textured materials in sandy soils formed in glacial drift. A study area in south-western Michigan was used to examine the relationship. Ground-penetrating radar was used to measure the depth to finer textured layers in the sandy soils on 25 study plots. White oak (Quercus alba L.) trees were measured for site index (height in meters at 50 yr) on those plots. Regression analysis revealed a negative correlation (r2 = 0.45) between site index and the depth to finer textured layers in these sandy soils. Dividing the plots into three groups based on depth to finer substrata (< 1.5 m, 1.5–2.9 m, and ≥ 3 m) revealed a significant difference among the groups. However, mean separation showed that only the < 1.5 m group differed significantly from the other two groups at the 0.05 level. While the depth to finer textured substrata does influence tree growth on these sandy soils, the influence appears to begin to wane at depths > 1.5 m. Key words: Forest productivity, ground-penetrating radar, sandy glacial drift, loamy substrata
HYDRAULIC CHARACTERISTICS OF FOUR PEATLANDS IN MINNESOTA
Authors: GAFNI ABRAHAM , BROOKS KENNETH N.
Published: March 2010

A field study in northern Minnesota was conducted to assess the relative importance of factors that control lateral water movement in peatlands. Hydraulic gradients and groundwater velocities were measured for one mined and three unmined peatlands. Groundwater velocities were measured at shallow depths in the organic soil using the point dilution method. Hydraulic conductivities at different soil depths were estimated by applying the field measurements to Darcy's Law. Hydraulic gradients were persistent from early summer through fall and were generally less than 0.1%, a major factor governing rates of lateral water movement in undisturbed peatlands. Maximum groundwater velocities averaged 0.49 cm h−1 in the upper and least decomposed peat layers and diminished dramatically with depth and increasing decomposition. The von-Post scale of peat decomposition was found to be useful in predicting the hydraulic conductivity of peat layers. The rate of water movement at depths below 35 cm in the natural peatlands averaged less than 0.03 cm h−1. The data contribute to a better understanding of the hydrologic function of peatlands. Key words: Organic soils, peatlands, groundwater velocity, hydraulic conductivity, hydraulic gradient